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Sample records for current hvdc transmission

  1. HVDC power transmission technology assessment

    Energy Technology Data Exchange (ETDEWEB)

    Hauth, R.L.; Tatro, P.J.; Railing, B.D. [New England Power Service Co., Westborough, MA (United States); Johnson, B.K.; Stewart, J.R. [Power Technologies, Inc., Schenectady, NY (United States); Fink, J.L.

    1997-04-01

    The purpose of this study was to develop an assessment of the national utility system`s needs for electric transmission during the period 1995-2020 that could be met by future reduced-cost HVDC systems. The assessment was to include an economic evaluation of HVDC as a means for meeting those needs as well as a comparison with competing technologies such as ac transmission with and without Flexible AC Transmission System (FACTS) controllers. The role of force commutated dc converters was to be assumed where appropriate. The assessment begins by identifying the general needs for transmission in the U.S. in the context of a future deregulated power industry. The possible roles for direct current transmission are then postulated in terms of representative scenarios. A few of the scenarios are illustrated with the help of actual U.S. system examples. non-traditional applications as well as traditional applications such as long lines and asynchronous interconnections are discussed. The classical ``break-even distance`` concept for comparing HVDC and ac lines is used to assess the selected scenarios. The impact of reduced-cost converters is reflected in terms of the break-even distance. This report presents a comprehensive review of the functional benefits of HVDC transmission and updated cost data for both ac and dc system components. It also provides some provocative thoughts on how direct current transmission might be applied to better utilize and expand our nation`s increasingly stressed transmission assets.

  2. New Comparison of HVDC and HVAC Transmission system

    Directory of Open Access Journals (Sweden)

    Vahid Behravesh

    2012-06-01

    Full Text Available Alternating current (AC is the main driving force in the industries and residential areas, but for the long transmission line (more than 400 miles AC transmission is more expensive than that of direct current (DC. Technically, AC transmission line control is more complicated because of the frequency. DC transmission does not have these limitations, which has led to build long HVDC transmission lines over the last 40 years. HVDC technology made possible to transfer bulk power over long distances. This paper presents a comparative evaluation of HVDC and HVAC transmission systems .

  3. Power Improvement of Transmission Line Using High Voltage Direct Current (Hvdc Transmission System

    Directory of Open Access Journals (Sweden)

    Lasisi, H

    2016-08-01

    Full Text Available The use of long EHV (Extremely High Voltage ac lines for the transmission of electrical energy increases the line reactance and susceptance which limits the thermal loadings on the line in order to keep sufficient margin against transient instability. With the scheme proposed in this paper, it is possible to load the lines very close to their limit with zero reactance and susceptance. The conductors are allowed to carry usual ac along with dc superimposed on it. The added dc power flow does not cause any transient instability. The scheme comprises a twelve-pulse bridge rectifier, dc-links, pulse width modulated (PSW-voltage sourced inverter (VSI and converter transformers. The master current controller is used to implement the scheme which senses ac current and regulates the dc current orders for converters online such that conductor current never exceeds its thermal limit. This paper gives the feasibility of converting a double circuit ac line into composite ac–dc power transmission line given the advantage of stability improvement, damping oscillations, voltage stabilization and reactive power compensation for ac weak buses. Simulation and experimental studies using MATLAB (Matrix Laboratory are carried out for the coordinated control as well as independent control of ac and dc power transmissions.

  4. Comparative study of superconducting fault current limiter both for LCC-HVDC and VSC-HVDC systems

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jong-Geon; Khan, Umer Amir; Lim, Sung-Woo; Shin, Woo-ju; Seo, In-Jin; Lee, Bang-Wook, E-mail: bangwook@hanyang.ac.kr

    2015-11-15

    Highlights: • The role of SFCL in types of HVDC system was evaluated. • A simulation model based on Korea Jeju–Haenam HVDC power system was designed in Matlab/Simulink. • Utilizing the designed both HVDC power system models, the efficiency of DC-SFCL was relatively low, compared to AC-SFCL. • It was deduced that the AC-SFCL was more effective in LCC-HVDC system than VSC-HVDC system. - Abstract: High Voltage Direct Current (HVDC) system has been evaluated as the optimum solution for the renewable energy transmission and long-distance power grid connections. In spite of the various advantages of HVDC system, it still has been regarded as an unreliable system compared to AC system due to its vulnerable characteristics on the power system fault. Furthermore, unlike AC system, optimum protection and switching device has not been fully developed yet. Therefore, in order to enhance the reliability of the HVDC systems mitigation of power system fault and reliable fault current limiting and switching devices should be developed. In this paper, in order to mitigate HVDC fault, both for Line Commutated Converter HVDC (LCC-HVDC) and Voltage Source Converter HVDC (VSC-HVDC) system, an application of resistive superconducting fault current limiter which has been known as optimum solution to cope with the power system fault was considered. Firstly, simulation models for two types of LCC-HVDC and VSC-HVDC system which has point to point connection model were developed. From the designed model, fault current characteristics of faulty condition were analyzed. Second, application of SFCL on each types of HVDC system and comparative study of modified fault current characteristics were analyzed. Consequently, it was deduced that an application of AC-SFCL on LCC-HVDC system with point to point connection was desirable solution to mitigate the fault current stresses and to prevent commutation failure in HVDC electric power system interconnected with AC grid.

  5. Comparative study of superconducting fault current limiter both for LCC-HVDC and VSC-HVDC systems

    Science.gov (United States)

    Lee, Jong-Geon; Khan, Umer Amir; Lim, Sung-Woo; Shin, Woo-ju; Seo, In-Jin; Lee, Bang-Wook

    2015-11-01

    High Voltage Direct Current (HVDC) system has been evaluated as the optimum solution for the renewable energy transmission and long-distance power grid connections. In spite of the various advantages of HVDC system, it still has been regarded as an unreliable system compared to AC system due to its vulnerable characteristics on the power system fault. Furthermore, unlike AC system, optimum protection and switching device has not been fully developed yet. Therefore, in order to enhance the reliability of the HVDC systems mitigation of power system fault and reliable fault current limiting and switching devices should be developed. In this paper, in order to mitigate HVDC fault, both for Line Commutated Converter HVDC (LCC-HVDC) and Voltage Source Converter HVDC (VSC-HVDC) system, an application of resistive superconducting fault current limiter which has been known as optimum solution to cope with the power system fault was considered. Firstly, simulation models for two types of LCC-HVDC and VSC-HVDC system which has point to point connection model were developed. From the designed model, fault current characteristics of faulty condition were analyzed. Second, application of SFCL on each types of HVDC system and comparative study of modified fault current characteristics were analyzed. Consequently, it was deduced that an application of AC-SFCL on LCC-HVDC system with point to point connection was desirable solution to mitigate the fault current stresses and to prevent commutation failure in HVDC electric power system interconnected with AC grid.

  6. Comparison of PI and PR current controllers applied on two-level VSC-HVDC transmission system

    DEFF Research Database (Denmark)

    Manoloiu, A.; Pereria, H.A.; Teodorescu, Remus;

    2015-01-01

    This paper analyzes differences between αβ and dq reference frames regarding the control of two-level VSC-HVDC current loop and dc-link voltage outer loop. In the first part, voltage feedforward effect is considered with PI and PR controllers. In the second part, the feedforward effect is removed...

  7. HVDC power transmission environmental issues review

    Energy Technology Data Exchange (ETDEWEB)

    Bailey, W.H.; Weil, D.E. [Bailey Research Associates, Inc., New York, NY (United States); Stewart, J.R. [Power Technologies, Inc., Schenectady, NY (United States)

    1997-04-01

    This report strives to define the various environmental effects associated with HVDC lines, discusses the current knowledge of their potential effects on biological and non-biological systems, and compares these effects associated with ac lines where appropriate.

  8. Innovations in the field of high-voltage direct current transmission (HVDC); Innovationen in der Hochspannungs-Gleichstrom-Uebertragungstechnik

    Energy Technology Data Exchange (ETDEWEB)

    Mukherjee, A.; Kurze, W.; Schramm, H.H.; Pereira, M.; Storner, C.; Ammon, J.; Plewka, G.; Wild, E. [Siemens AG, Erlangen (Germany). Bereich Energieuebertragung und -verbreitung; Uder, M. [Siemens AG, Erlangen (Germany). Bereich Automatisierungs- und Antriebstechnik; Schaller, G. [Erlangen-Nuernberg Univ. (Germany)

    1998-10-05

    This paper describes some new developments from different fields of HVDC technology: The use of direct light-triggered thyristors instead of the conventional electrically triggered ones; a new hybrid-optical measuring method for direct currents at high voltage potential in place of conventional transducers of zeroflux type; a new type of HVDC SF{sub 6}-circuit-breaker, developed for use as Metallic Return Transfer Breaker (MRTB), combining all advantages of an SF{sub 6}-breaker against an air-blast breaker; active filters using power electronics - as a purposeful supplement to passive filters - to reduce the harmonics to negligible levels; the new pulse-echo monitoring system for electrode lines offering a number of advantages over conventional systems (e.g. impedance measurement). All these new but successfully tested techniques and equipment go to enhance the reliability and economy of HVDC systems and therefore set future trends. (orig.) [Deutsch] An ausgewaehlten Beispielen aus verschiedenen Gebieten der HGUe-Technik berichten die Verfasser ueber einige Neuentwicklungen, z.B.: den Einsatz von direkt lichtzuendbaren Thyristoren anstelle von elektrisch zuendbaren; ein neues hybrid-optisches Gleichstrom-Messsystem im Vergleich mit konventionellen Messmethoden mit Nullflusswandlern; SF{sub 6}-Gleichstromschalter - anstelle von Druckluftschaltern beim Einsatz als Metallic Return Transfer Breaker (MRTB); aktiver Filter mit leistungselektronischen Komponenten - als Ergaenzung zu passiven Filtern zur Daempfung von Oberschwingungen ein neues Puls-Echo-Ueberwachungssystem fuer HGUe-Elektrodenleitungen, das bisherigen Methoden, z.B. Impedanzmessung, deutlich ueberlegen ist. Alle diese neuen aber erfolgreich erprobten Techniken erhoehen die Zuverlaessigkeit und Wirtschaftlichkeit von HGUe-Anlagen und sind daher zukunftsweisend. (orig.)

  9. The New Breakthrough in Technical Standards for HVDC Transmission Equipments

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Project Name:12 Standards including GB/T 20838-2007 Technical Parameters and Requirements for HVDC Oil Immersed Convector Transformer Main Participant Units:Economic Research Institute,Xi'an High Voltage Apparatus Research Institute Co.Ltd.,Shenyang Transformer Academy,Xi'an Power Electronics Research Institute,China Electric Power Research Institute,TBEA Shenyang Transformer Group Corporation,China Southern Power Grid Technology Research Center Main Contributors:Fang Xiaoyan,Gou Ruifeng,Zhang Zhonguo,Yu Hongqi,Wang Mingxin,Mi Chuanlong,Wang Jian,Rao Hong,Guo Liping,Liu Jing Award Grade:First Prize Backg round High Voltage Direct Current Transmission (HVDC) is an important means to address issues of high voltage,high power,long distance and asynchronous grid-connection,and has been listed in the national mid-term and long-term science and technology development plan.The world-famous Three Gorges Project (TGP) was designed to use HVDC technology in two-thirds of electric power transmission according to the TGP plan.So it is of significance to develop HVDC in China for improvement of transmission capacity and quality.

  10. Assessment on the influence of resistive superconducting fault current limiter in VSC-HVDC system

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jong-Geon; Khan, Umer Amir; Hwang, Jae-Sang; Seong, Jae-Kyu; Shin, Woo-Ju; Park, Byung-Bae; Lee, Bang-Wook, E-mail: bangwook@hanyang.ac.kr

    2014-09-15

    Highlights: • The role of SFCLs in VSC-HVDC systems was evaluated. • Simulation model based on Korea Jeju-Haenam HVDC power system was designed. • An effect and the feasible locations of resistive SFCLs were evaluated. • DC line-to-line, DC line-to-ground and 3 phase AC faults were imposed and analyzed. - Abstract: Due to fewer risk of commutation failures, harmonic occurrences and reactive power consumptions, Voltage Source Converter (VSC) based HVDC system is known as the optimum solution of HVDC power system for the future power grid. However, the absence of suitable fault protection devices for HVDC system hinders the efficient VSC-HVDC power grid design. In order to enhance the reliability of the VSC-HVDC power grid against the fault current problems, the application of resistive Superconducting Fault Current Limiters (SFCLs) could be considered. Also, SFCLs could be applied to the VSC-HVDC system with integrated AC Power Systems in order to enhance the transient response and the robustness of the system. In this paper, in order to evaluate the role of SFCLs in VSC-HVDC systems and to determine the suitable position of SFCLs in VSC-HVDC power systems integrated with AC power System, a simulation model based on Korea Jeju-Haenam HVDC power system was designed in Matlab Simulink/SimPowerSystems. This designed model was composed of VSC-HVDC system connected with an AC microgrid. Utilizing the designed VSC-HVDC systems, the feasible locations of resistive SFCLs were evaluated when DC line-to-line, DC line-to-ground and three phase AC faults were occurred. Consequently, it was found that the simulation model was effective to evaluate the positive effects of resistive SFCLs for the effective suppression of fault currents in VSC-HVDC systems as well as in integrated AC Systems. Finally, the optimum locations of SFCLs in VSC-HVDC transmission systems were suggested based on the simulation results.

  11. Corrosive effects of hvdc transmission

    Energy Technology Data Exchange (ETDEWEB)

    Cornwell, F.E.; Backstrom, T.E.

    1966-02-01

    Field tests using ac transmission lines for introduction of direct current into the earth at widely separated points are described. One test circuit was between a Tracy pumping plant and a Shasta power plant in California, and two others were in the Hoover power plant area. Evaluation of the effects of such ground currents on corrosion of buried metalwork was a primary aim of the tests. Potential gradients, pipe-to-soil potentials, and soil resistivities are discussed in detail. Estimates are made of the distances from ehv dc terminal installations within which corrosion prevention procedures may become necessary.

  12. Assessment on the influence of resistive superconducting fault current limiter in VSC-HVDC system

    Science.gov (United States)

    Lee, Jong-Geon; Khan, Umer Amir; Hwang, Jae-Sang; Seong, Jae-Kyu; Shin, Woo-Ju; Park, Byung-Bae; Lee, Bang-Wook

    2014-09-01

    Due to fewer risk of commutation failures, harmonic occurrences and reactive power consumptions, Voltage Source Converter (VSC) based HVDC system is known as the optimum solution of HVDC power system for the future power grid. However, the absence of suitable fault protection devices for HVDC system hinders the efficient VSC-HVDC power grid design. In order to enhance the reliability of the VSC-HVDC power grid against the fault current problems, the application of resistive Superconducting Fault Current Limiters (SFCLs) could be considered. Also, SFCLs could be applied to the VSC-HVDC system with integrated AC Power Systems in order to enhance the transient response and the robustness of the system. In this paper, in order to evaluate the role of SFCLs in VSC-HVDC systems and to determine the suitable position of SFCLs in VSC-HVDC power systems integrated with AC power System, a simulation model based on Korea Jeju-Haenam HVDC power system was designed in Matlab Simulink/SimPowerSystems. This designed model was composed of VSC-HVDC system connected with an AC microgrid. Utilizing the designed VSC-HVDC systems, the feasible locations of resistive SFCLs were evaluated when DC line-to-line, DC line-to-ground and three phase AC faults were occurred. Consequently, it was found that the simulation model was effective to evaluate the positive effects of resistive SFCLs for the effective suppression of fault currents in VSC-HVDC systems as well as in integrated AC Systems. Finally, the optimum locations of SFCLs in VSC-HVDC transmission systems were suggested based on the simulation results.

  13. Negative sequence current control in wind power plants with VSC-HVDC connection

    DEFF Research Database (Denmark)

    Chaudhary, Sanjay; Teodorescu, Remus; Rodriguez, Pedro;

    2012-01-01

    Large offshore wind power plants may have multi-MW wind turbine generators (WTG) equipped with full-scale converters (FSC) and voltage source converter (VSC) based high voltaage direct-current (HVDC) transmission for grid connection. The power electronic converters in theWTG-FSC and the VSC-HVDC...... allow fast current control in the offshore grid. This paper presents a method of controlling the negative sequence current injection into the offshore grid from the VSC-HVDC as well as WTG-FSCs. This would minimize the power oscillations and hence reduce the dc voltage overshoots in the VSC-HVDC system...... sequence current control mitigates the power oscillations and therefore limits the dc voltage excursions in the VSC-HVDC system during the asymmetric faults....

  14. Cost estimation of HVDC transmission system of Bangka's NPP candidates

    Science.gov (United States)

    Liun, Edwaren; Suparman

    2014-09-01

    Regarding nuclear power plant development in Bangka Island, it can be estimated that produced power will be oversupply for the Bangka Island and needs to transmit to Sumatra or Java Island. The distance between the regions or islands causing considerable loss of power in transmission by alternating current, and a wide range of technical and economical issues. The objective of this paper addresses to economics analysis of direct current transmission system to overcome those technical problem. Direct current transmission has a stable characteristic, so that the power delivery from Bangka to Sumatra or Java in a large scale efficiently and reliably can be done. HVDC system costs depend on the power capacity applied to the system and length of the transmission line in addition to other variables that may be different.

  15. Innovation on Energy Power Technology (8)First HVDC Transmission System in Japan

    Science.gov (United States)

    Sampei, Masatoshi

    This paper is an episode concerning the Hokkaido-Honshu HVDC Link that is the first High Voltage DC Current transmission system in Japan. The effort to the commissioning of the first stage of this system is explained. Moreover, it explains the research and development executed to achieve 600MW of this system that is the final stage. In addition, the adoption episode of the frequency control method introduced for Hokkaido-Honshu HVDC Link is explained.

  16. 高压直流输电用无源型直流转换开关电弧电流特性研究%Arc Current Characteristic of DC Circuit Breaker in HVDC Transmission and Distribution System

    Institute of Scientific and Technical Information of China (English)

    那虎; 丁正平; 孙晋峰; 杨俊清; 刘龙开; 袁芳; 洪深

    2012-01-01

    直流输变电系统用无源型高压直流转换开关是直流系统中的重要运行设备,其运行工况及工作特性极其特殊.笔者通过对高压直流转换开关工作原理及工况进行研究,并依据试验测得的断口电弧电流曲线的特征,对高压直流转换开关开断转换电流的电弧电流特性进行理论研究及分析,给出了电弧电流特性函数,指出高压直流转换开关开断的关键点是断口的弧阻小,变化率大,L1C1辅助支路频率高,才能开断较大的直流电流.%The passive high-voltage direct current (HVDC)circuit breaker is important for ensuring reliability of HVDC distribution system, and its working condition and characteristic are particular. In this paper, the working condition and characteristic of HVDC circuit breaker in HVDC transmission and distribution system are analyzed, the arc current characteristic of the breaker is investigated according to test data, and a function for describing arc current characteristic of the breaker is achieved. Conclusion is drawn that small arcing resistance, high varying rate, and high frequency of L1C1 circuit can facilitate breaking larger direct current by HVDC circuit breaker.

  17. Unified active and reactive power modulation of HVDC transmission systems

    Science.gov (United States)

    Grund, C. E.; Pohl, R. V.

    1981-11-01

    The power modulation of a high voltage direct current (HVDC) system for stabilization of an ac/dc network was investigated. It was found that simultaneous modulation of both dc current and voltage was more effective than just current modulation by itself, since the dc voltage modulation could be used to minimize the reactive power changes resulting from a change of the dc current. This helps stabilize the ac busbar voltages at the converters, which reduces undesirable load flow changes to voltage dependent ac loads, thus improving the effectiveness of the dc power modulation. This unified modulation control concept was evaluated by means of digital computer studies as well as a special purpose HVDC simulator. Several combined ac/dc power transmission systems were synthesized for testing of different modulation controller concepts. An optimum controller design incorporating a linear quadratic control algorithm with full state feedback was first studied. This provided a basis for comparison of suboptimal controller designs utilizing reduced state feedback and a Kalman filter state reconstruction technique.

  18. Optimisation of VSC-HVDC Transmission for Wind Power Plants

    DEFF Research Database (Denmark)

    Silva, Rodrigo Da

    Connection of Wind Power Plants (WPP), typically oshore, using VSCHVDC transmission is an emerging solution with many benefits compared to the traditional AC solution, especially concerning the impact on control architecture of the wind farms and the grid. The VSC-HVDC solution is likely to meet...... more stringent grid codes than a conventional AC transmission connection. The purpose of this project is to analyse how HVDC solution, considering the voltage-source converter based technology, for grid connection of large wind power plants can be designed and optimised. By optimisation, the project...... the requirements established by the operators in the multiterminal VSC-HVDC transmission system. Moreover, the possibility in minimising the overall transmission losses can be a solution for small grids and the minimisation in the dispatch error is a new solution for power deliver maximisation. The second study...

  19. A Hybrid LCC-VSC HVDC Transmission System Supplying a Passive Load

    Science.gov (United States)

    Kotb, Omar

    High Voltage Direct Current (HVDC) transmission systems continue to be an excellent asset in modern power systems, mainly for their ability to overcome the problems of AC transmission, such as the interconnection of asynchronous grids, stability of long transmission lines, and use of long cables for power transmission. In the past 20 years, Voltage Source Converter (VSC)-HVDC transmission systems were developed and installed in many projects, thereby adding more operational benefits to DC transmission option, such as high controllability, ability to supply weak networks, and reduced converter reactive power demand. Nevertheless, VSC-HVDC transmission suffers from the disadvantages of high losses and cost. In this research, a hybrid HVDC employing a Line Commutated Converter (LCC) as rectifier and a VSC as inverter is used to supply a passive network through a DC cable. The hybrid system is best suited for unidirectional power transmission scenarios, such as power transmission to islands and remote load centers, where the construction of new transmission lines is prohibitively expensive. Control modes for the rectifier and inverter are selected and implemented using Proportional Integral (PI) controllers. Special control schemes are developed for abnormal operating conditions such as starting at light load and recovering from AC network faults. The system performance under steady state and transient conditions is investigated by EMTP-RV simulations. The results show the feasibility of the hybrid system.

  20. Aswan HighDam/Cairo proposed HVDC transmission system

    Directory of Open Access Journals (Sweden)

    Ahmed Y.M.R. Salama

    2014-03-01

    The DC lines can carry more much power with two conductors than the power transmitted using an AC lines with three conductors of the same size. For the given power level, a DC line requires simpler and cheaper towers (From economical point of view, already installed towers for AC system can be used. Also reduced conductor sizes and insulator can be used. The power transmission losses also will be reduced to about two-thirds of the comparable AC system. The absence of skin effect with DC is also beneficial in reducing power losses marginally. Due to its fast controllability, HVDC transmission system has full control over transmitted power, an ability to enhance transient and dynamic stability in associated AC networks and can limit fault currents levels in the DC lines.

  1. Transmission of Power to the Island Using HVDC

    Directory of Open Access Journals (Sweden)

    B. Vijayalakshmi

    2012-09-01

    Full Text Available HVDC transmission is more effective andeconomically cheaper where bulk power is to betransmitted over long distance. Hence the surpluspower from a remote place can be exported to theneedy place at cheaper rate. The HVDC systemrequire only one transmission wire and the groundreturn or seawater can be used as an another line.The Lakshadweep Island is located at faraway placefrom the northeast part of India where the surpluspower is available. The seawater for return path isavailable. The diesel for D.G set is transported fromIndian mainland through ship where lot of economyis lost only for transportation. In this paper thetransmission of HVDC from Indian mainland toLakshadweep is analyzed at economically cheaperrate.

  2. DC Vs AC - War Of Currents For Future Power Systems A HVDC Technology Overview

    Directory of Open Access Journals (Sweden)

    Anil K. Rai

    2015-08-01

    Full Text Available DC vs AC discussion began in 1880s with development of first commercial power transmission in Wall Street New York. Later when AC technology came into notice by efforts of inventor and researcher Sir Nicola Tesla soon the advantages of AC transmission and AC devices overtook the DC technology. It was hoped that DC technology had lost battle of currents. Today with researches going on FACTS devices and bulk power transmission HVDC has again gained a reputation in power sector. Solution of this centuries old debate is to develop HVDC systems that assists HVAC systems for better performance stability and control

  3. Control strategies for VSC-based HVDC transmission system

    DEFF Research Database (Denmark)

    Stan, Ana-Irina; Stroe, Daniel Ioan; Silva, Rodrigo Da

    2011-01-01

    the behavior of the developed VSC-based HVDC transmission system two study cases are carried out using MATLAB/Simulink. The results obtained from simulations show acceptable performances, of the proposed strategies, when changes in the reference parameters are considered. The active power flow between...

  4. Influence of current limitation on voltage stability with voltage sourced converter HVDC

    DEFF Research Database (Denmark)

    Zeni, Lorenzo; Jóhannsson, Hjörtur; Hansen, Anca Daniela;

    2013-01-01

    A first study of voltage stability with relevant amount of Voltage Sourced Converter based High Voltage Direct Current (VSC-HVDC) transmission is presented, with particular focus on the converters’ behaviour when reaching their rated current. The detrimental effect of entering the current...

  5. System Design of HVDC Project

    Institute of Scientific and Technical Information of China (English)

    Ma Weimin; Yin Weiyang

    2011-01-01

    BackgroundHVDC transmission system is flexible,controllable,economic and environmentfriendly,which has compelling advantages in bulk long-distance power transfer and interconnection of power systems.Since the first HVDC project was put into commercial operation in Gotland in 1954,over 100 HVDC projects have been operating in the world.Currently,there are a number of HVDC projects under being upgraded,constructed or planed in Europe,North America,South America,Africa and Asia.

  6. Research of Bipolar HVDC Transmission Lines Based on Traveling Wave Differential Protection

    Directory of Open Access Journals (Sweden)

    Baina He

    2013-07-01

    Full Text Available The principle of the traveling wave based differential protection for bipolar HVDC transmission lines is proposed in the paper. Unlike the traditional current differential protection, the quantity of current is replaced by the quantity of the traveling wave for comparison. The traveling wave at the remote end is transferred to the local end for comparison to the local traveling wave. For the bipolar DC transmission lines, the polar-mode (aerial mode traveling waves are employed to establish the discriminative criterion. The ground-mode traveling waves are utilized for faulty line detector for bipolar operation modes. The entire protection scheme is simulated in PSCAD/EMTDC associated with the standard ±500kV HVDC transmission system. The simulation results show that the new protection has the advantages of higher sensitivity, reliability and security. The fault resistance can be coverd by the traveling wave based differential protection reaches to 500 Ohm.    

  7. Statistics and Analysis on Reliability of HVDC Transmission Systems of SGCC

    Institute of Scientific and Technical Information of China (English)

    Xu

    2010-01-01

    Reliability level of HVDC power transmission systems becomes an important factor impacting the entire power grid. The author analyzes the reliability of HVDC power transmission systems owned by SGCC since 2003 in respect of forced outage times, forced energy unavailability, scheduled energy unavailability and energy utilization efficiency. The results show that the reliability level of HVDC power transmission systems owned by SGCC is improving. By analyzing different reliability indices of HVDC power transmission system, the maximum asset benefits of power grid can be achieved through building a scientific and reasonable reliability evaluation system.

  8. A novel synthetic test system for thyristor level in the converter valve of HVDC power transmission

    Directory of Open Access Journals (Sweden)

    Liu Longchen

    2016-01-01

    Full Text Available The converter valve is the core equipment in the HVDC power transmission system, a+-nd its performance has a direct effect on the reliability, stability and efficiency of the whole power system. As the basic unit of HVDC converter valve, the thyristor level needs to be test routinely in order to grasp the state of the converter valve equipment. Therefore, it is urgent to develop a novel synthetic test system for the thyristor level with thyristor control unit (TCU. However, currently there is no specific test scheme for the thyristor level of HVDC converter valve. In this paper, the synthetic test principle, content and methods for the thyristor level with TCU are presented based on the analysis of the thyristor reverse recovery characteristic and the IEC technology standard. And a transient high-voltage pulse is applied to the thyristor level during its reverse recovery period in order to test the characteristics of thyristor level. Then, the synthetic test system for the thyristor level is applied to the converter valve test of ±800 kV HVDC power transmission project, and the practical test result verifies the reasonability and validity of the proposed synthetic test system.

  9. Investigation of multimodule buck–boost inverter-based HVDC transmission system

    Directory of Open Access Journals (Sweden)

    Ahmed A. Elserougi

    2015-01-01

    Full Text Available In high voltage direct current (HVDC systems, the semiconductor devices have to be connected in series to obtain the required high-voltage ratings. This study proposes a new HVDC configuration, namely, multimodule buck–boost inverter for HVDC transmission applications which avoids series connection of large number of semiconductor switches. In addition, it provides a blocking capability against DC side faults. The proposed configuration consists of several simple buck–boost converters which are assembled together to meet the requirements of high-voltage high-power applications. This paper studies the dynamic performance of the proposed system under different operating conditions, and the results were satisfactory. The main advantages of the proposed configuration are: (i pure sinusoidal output which minimises/eliminates the requirements for supplementary AC filters and offers an inherent suppression to the common mode voltages, (ii very low dv/dt stresses and (iii complete blocking capability of AC side contributions during DC side faults. This study discusses the system architecture, passive components selections, voltage and current ratings of its semiconductor devices and the required controllers. A comparison between the proposed configuration and other existing HVDC technologies is also presented in this study.

  10. Design of protective inductors for HVDC transmission line within DC grid offshore wind farms

    DEFF Research Database (Denmark)

    Deng, Fujin; Chen, Zhe

    2013-01-01

    This paper presents fault analysis and protective inductors design for an offshore wind farm, where the power collection system in the wind farm and the power transmission link to the grid adopt high-voltage direct-current (HVDC) technology. This paper focuses on dealing with short-circuit faults...... in the HVDC link between the offshore station and the onshore station. The transient characteristics of the transmission system are analyzed in detail. The criteria of selecting protective inductors are proposed to effectively limit the short-circuit current and avoid the damage to the converters. A dc grid...... offshore wind farm is simulated, and the results demonstrate the effectiveness of the proposed protective inductors design....

  11. Coordinated frequency regulation by offshore wind farms and VSC-HVDC transmission

    DEFF Research Database (Denmark)

    Liu, Hongzhi; Chen, Zhe

    2014-01-01

    With the increasing wind penetration, large-scale offshore wind farms exert significant impact on power system security and operation, and thus are required to contribute to system frequency regulation. This paper develops a coordinated control strategy for offshore wind farms with voltage source...... converter-based HVDC (VSC-HVDC) transmission system to participate in power system frequency regulation. The strategy explores the frequency support capability of offshore wind farms and VSC-HVDC. By implementing the proposed coordinated control, the VSCHVDC link is able to provide quick virtual inertial...... are presented to demonstrate the frequency regulation capability of VSC-HVDC and validate the effectiveness of the proposed coordinated control strategy....

  12. 一种新型的高压直流输电技术——MMC-HVDC%New HVDC power transmission technology:MMC-HVDC

    Institute of Scientific and Technical Information of China (English)

    韦延方; 卫志农; 孙国强; 郑玉平; 俞波

    2012-01-01

    The structure,operational principle and technical features of MMC-HVDC are described and the differences between MMC-HVDC and VSC-HVDC are compared. A brief survey is made on the present research statuses and engineering applications of MMC-HVDC. The drawbackes and some possible important trends of MMC-HVDC are analyzed,including:MMC-topology-related research,system design,fault protection, grounding,harmonics,loss,and so on. It is pointed out that the MMC-HVDC model for current research has low precision. For the limit of MMC topology,the mature control methods of VSC-HVDC can not be directly applied to MMC-HVDC. MMC-HVDC system has a strong ability of fault protection. Since current research emphasizes on the simulative analysis of fault protection,further research of MMC-HVDC protection strategy suitable for engineering applications is urgently needed. The implementation of grounding is difficult for high voltage capacitor banks are removed. For the large number of MMC sub-module,the better output voltage waveform is obtained when low switching frequency is used,and the system loss is low. The engineering practice of MMC-HVDC fit for China is discussed.%介绍了模块化多电平换流器型高压直流输电(MMC-HVDC)的基本结构,工作原理和技术特点,比较了MMC-HVDC相对于电压源换流器型高压直流输电(VSC-HVDC)的优势;对MMC-HVDC目前在国内外的研究进展和工程应用情况进行了回顾,分析了MMC-HVDC技术的不足之处和未来发展中可能的重点方向,包括主电路拓扑的相关问题研究、系统设计、故障保护、接地、谐波和损耗等,指出目前研究所采用的MMC-HVDC分析模型精度较低;因自身拓扑限制,目前成熟的VSC-HVDC控制方法无法直接用于MMC-HVDC; MMC-HVDC拥有较强的故障保护能力,当前研究着重于故障仿真分析,亟待探讨适合工程应用的保护策略;由于直流侧无需安装高压电容器组,MMC-HVDC接地实现困难;由于MMC-HVDC

  13. Performance analysis of a model-sized superconducting DC transmission system based VSC-HVDC transmission technologies using RTDS

    Science.gov (United States)

    Dinh, Minh-Chau; Ju, Chang-Hyeon; Kim, Sung-Kyu; Kim, Jin-Geun; Park, Minwon; Yu, In-Keun

    2012-08-01

    The combination of a high temperature superconducting DC power cable and a voltage source converter based HVDC (VSC-HVDC) creates a new option for transmitting power with multiple collection and distribution points for long distance and bulk power transmissions. It offers some greater advantages compared with HVAC or conventional HVDC transmission systems, and it is well suited for the grid integration of renewable energy sources in existing distribution or transmission systems. For this reason, a superconducting DC transmission system based HVDC transmission technologies is planned to be set up in the Jeju power system, Korea. Before applying this system to a real power system on Jeju Island, system analysis should be performed through a real time test. In this paper, a model-sized superconducting VSC-HVDC system, which consists of a small model-sized VSC-HVDC connected to a 2 m YBCO HTS DC model cable, is implemented. The authors have performed the real-time simulation method that incorporates the model-sized superconducting VSC-HVDC system into the simulated Jeju power system using Real Time Digital Simulator (RTDS). The performance analysis of the superconducting VSC-HVDC systems has been verified by the proposed test platform and the results were discussed in detail.

  14. Design, control and application of modular multilevel converters for HVDC transmission systems

    CERN Document Server

    Sharifabadi, Kamran; Nee, Hans-Peter; Norrga, Staffan; Teodorescu, Remus

    2016-01-01

    Design, Control and Application of Modular Multilevel Converters for HVDC Transmission Systems is a comprehensive guide to semiconductor technologies applicable for MMC design, component sizing control, modulation, and application of the MMC technology for HVDC transmission. Separated into three distinct parts, the first offers an overview of MMC technology, including information on converter component sizing, Control and Communication, Protection and Fault Management, and Generic Modelling and Simulation. The second covers the applications of MMC in offshore WPP, including planning, technical and economic requirements and optimization options, fault management, dynamic and transient stability. Finally, the third chapter explores the applications of MMC in HVDC transmission and Multi Terminal configurations, including Supergrids.

  15. HVDC transmission power conversion applications in power systems

    CERN Document Server

    Kim, Chan-Ki; Jang, Gil-Soo; Lim, Seong-Joo; Lee, Seok-Jin

    2009-01-01

    HVDC is a critical solution to several major problems encountered when trying to maintain systemic links and quality in large-scale renewable energy environments. HDVC can resolve a number of issues, including voltage stability of AC power networks, reducing fault current, and optimal management of electric power, ensuring the technology will play an increasingly important role in the electric power industry. To address the pressing need for an up-to-date and comprehensive treatment of the subject, Kim, Sood, Jang, Lim and Lee have collaborated to produce this key text and reference.  Combin

  16. HVDC power transmission electrode siting and design

    Energy Technology Data Exchange (ETDEWEB)

    Holt, R.J. [NDT Engineering, Inc., Shrewbury, MA (United States); Dabkowski, J. [Electro-Sciences, Inc., Crystal Lake, IL (United States); Hauth, R.L. [New England Power Service Co., Westborough, MA (United States)

    1997-04-01

    This research strives to shed light on the feasibility and practicality of using deep earth electrodes to permit their use for extended periods without adverse consequences. This report begins with a review of the fundamentals associated with current conduction in earth, including the various techniques available for measuring the earth`s electrical properties. The sources of existing data are discussed and some specific data for selected regions of the U.S. and Canada are reviewed as examples. Electrode technology and design issues are reviewed and recent experience gained by New England Power and Hydro-Quebec is discussed. The issues associated with direct current flowing in underground pipelines (and other facilities) are described and the present-day mitigation measures are evaluated. Suggestions are made for further R&D in the coordination of cathodic protection systems, an area that has evolved as an empirical, trial- and-error art more than a science.

  17. An Annotated Bibliography of High-Voltage Direct-Current Transmission and Flexible AC Transmission (FACTS) Devices, 1991-1993.

    Energy Technology Data Exchange (ETDEWEB)

    Litzenberger, Wayne; Lava, Val

    1994-08-01

    References are contained for HVDC systems, converter stations and components, overhead transmission lines, cable transmission, system design and operations, simulation of high voltage direct current systems, high-voltage direct current installations, and flexible AC transmission system (FACTS).

  18. Cost estimation of HVDC transmission system of Bangka’s NPP candidates

    Energy Technology Data Exchange (ETDEWEB)

    Liun, Edwaren, E-mail: edwaren@batan.go.id; Suparman, E-mail: edwaren@batan.go.id [Centre for Nuclear Energy Development, National Nuclear Energy Agency of Indonesia (Indonesia)

    2014-09-30

    Regarding nuclear power plant development in Bangka Island, it can be estimated that produced power will be oversupply for the Bangka Island and needs to transmit to Sumatra or Java Island. The distance between the regions or islands causing considerable loss of power in transmission by alternating current, and a wide range of technical and economical issues. The objective of this paper addresses to economics analysis of direct current transmission system to overcome those technical problem. Direct current transmission has a stable characteristic, so that the power delivery from Bangka to Sumatra or Java in a large scale efficiently and reliably can be done. HVDC system costs depend on the power capacity applied to the system and length of the transmission line in addition to other variables that may be different.

  19. A Pilot Directional Protection for HVDC Transmission Line Based on Relative Entropy of Wavelet Energy

    Directory of Open Access Journals (Sweden)

    Sheng Lin

    2015-07-01

    Full Text Available On the basis of analyzing high-voltage direct current (HVDC transmission system and its fault superimposed circuit, the direction of the fault components of the voltage and the current measured at one end of transmission line is certified to be different for internal faults and external faults. As an estimate of the differences between two signals, relative entropy is an effective parameter for recognizing transient signals in HVDC transmission lines. In this paper, the relative entropy of wavelet energy is applied to distinguish internal fault from external fault. For internal faults, the directions of fault components of voltage and current are opposite at the two ends of the transmission line, indicating a huge difference of wavelet energy relative entropy; for external faults, the directions are identical, indicating a small difference. The simulation results based on PSCAD/EMTDC show that the proposed pilot protection system acts accurately for faults under different conditions, and its performance is not affected by fault type, fault location, fault resistance and noise.

  20. Offshore grid transmission planning using approximated HVDC power flows

    Energy Technology Data Exchange (ETDEWEB)

    Torbaghan, Shahab Shariat; Rawn, Barry G.; Gibescu, Madeleine; Meijden, Mart van der [Delft Univ. of Technology (Netherlands). Dept. of Electrical Sustainable Energy

    2012-07-01

    In this paper we introduce an optimization framework which determines a socially optimum design of a HVDC offshore grid, under the assumption of a centralized network expansion planning scheme. This gives the optimum grid topology and interconnections capacity. In addition, the analytical solution to the optimization problem yields a market structure that expresses the relationship between the different regions' electricity prices and congestion charges associated with the interconnections. The optimization model sets the transmission capacities in a way that congestion shadow prices to be collected by the end of the economic lifetime of the project pay off the initial investment capital. We use this framework to study the impact of exercising different dispatching policies on the optimum design of the grid. The framework is applied to a multi-bus test system that functions under 8 different time periods. (orig.)

  1. An Initial Topology of Multi-terminal HVDC Transmission System in Europe

    DEFF Research Database (Denmark)

    Irnawan, Roni; Silva, Filipe Miguel Faria da; Bak, Claus Leth;

    2016-01-01

    In this paper, technical challenges for realizing offshore multi-terminal HVDC (MTDC) transmission system in Europe is evaluated. An offshore MTDC topology is projected by interconnecting point-to-point HVDC links with the same voltage level and technology found in south-eastern part of North Sea....... Availability analysis is done to evaluate the feasibility of the proposed offshore MTDC topology. As compared to point-to-point (PtP) HVDC link, MTDC operation gives a more secure and reliable system. This paper shows that the proposed MTDC topology can operate 98.36% of the time....

  2. Modular VSC converter based HVDC power transmission from offshore wind power plant: Compared to the conventional HVAC system

    DEFF Research Database (Denmark)

    Sharma, Ranjan; Rasmussen, Tonny Wederberg; Jensen, Kim Høj;

    2010-01-01

    power transmission options with HVDC systems are under consideration. In this paper, a comparison between a conventional HVAC transmission system and a HVDC system equipped with modular voltage source converters is provided. The comparison is based on the total energy transmission capability...

  3. Suggested Methods for Preventing Core Saturation Instability in HVDC Transmission Systems

    Energy Technology Data Exchange (ETDEWEB)

    Norheim, Ian

    2002-07-01

    In this thesis a study of the HVDC related phenomenon core saturation instability and methods to prevent this phenomenon is performed. It is reason to believe that this phenomenon caused disconnection of the Skagerrak HVDC link 10 August 1993. Internationally, core saturation instability has been reported at several HVDC schemes and thorough complex studies of the phenomenon has been performed. This thesis gives a detailed description of the phenomenon and suggest some interesting methods to prevent the development of it. Core saturation instability and its consequences can be described in a simplified way as follows: It is now assumed that a fundamental harmonic component is present in the DC side current. Due to the coupling between the AC side and the DC side of the HVDC converter, a subsequent second harmonic positive-sequence current and DC currents will be generated on the AC side. The DC currents will cause saturation in the converter transformers. This will cause the magnetizing current to also have a second harmonic positive-sequence component. If a high second harmonic impedance is seen from the commutation bus, a high positive-sequence second harmonic component will be present in the commutation voltages. This will result in a relatively high fundamental frequency component in the DC side voltage. If the fundamental frequency impedance at the DC side is relatively low the fundamental component in the DC side current may become larger than it originally was. In addition the HVDC control system may contribute to the fundamental frequency component in the DC side voltage, and in this way cause a system even more sensitive to core saturation instability. The large magnetizing currents that eventually will flow on the AC side cause large zero-sequence currents in the neutral conductors of the AC transmission lines connected to the HVDC link. This may result in disconnection of the lines. Alternatively, the harmonics in the large magnetizing currents may cause

  4. Suggested Methods for Preventing Core Saturation Instability in HVDC Transmission Systems

    Energy Technology Data Exchange (ETDEWEB)

    Norheim, Ian

    2002-07-01

    In this thesis a study of the HVDC related phenomenon core saturation instability and methods to prevent this phenomenon is performed. It is reason to believe that this phenomenon caused disconnection of the Skagerrak HVDC link 10 August 1993. Internationally, core saturation instability has been reported at several HVDC schemes and thorough complex studies of the phenomenon has been performed. This thesis gives a detailed description of the phenomenon and suggest some interesting methods to prevent the development of it. Core saturation instability and its consequences can be described in a simplified way as follows: It is now assumed that a fundamental harmonic component is present in the DC side current. Due to the coupling between the AC side and the DC side of the HVDC converter, a subsequent second harmonic positive-sequence current and DC currents will be generated on the AC side. The DC currents will cause saturation in the converter transformers. This will cause the magnetizing current to also have a second harmonic positive-sequence component. If a high second harmonic impedance is seen from the commutation bus, a high positive-sequence second harmonic component will be present in the commutation voltages. This will result in a relatively high fundamental frequency component in the DC side voltage. If the fundamental frequency impedance at the DC side is relatively low the fundamental component in the DC side current may become larger than it originally was. In addition the HVDC control system may contribute to the fundamental frequency component in the DC side voltage, and in this way cause a system even more sensitive to core saturation instability. The large magnetizing currents that eventually will flow on the AC side cause large zero-sequence currents in the neutral conductors of the AC transmission lines connected to the HVDC link. This may result in disconnection of the lines. Alternatively, the harmonics in the large magnetizing currents may cause

  5. Loss evaluation of HVAC and HVDC transmission solutions for large offshore wind farms

    Energy Technology Data Exchange (ETDEWEB)

    Negra, N. Barberis [Politecnico of Turin, Department of Electrical Engineering (Italy); Todorovic, J. [ELEKTROPRENOS, Banja Luka (Bosnia and Herzegovina); Ackermann, T. [Royal Institute of Technology, Teknikringen 33, 10044 Stockholm (Sweden)

    2006-07-15

    This paper presents a comparison of transmission losses for different technical transmission solutions for large offshore wind farms. Three technical solutions are analyzed, i.e. HVAC, HVDC Line Commutated Converter (LCC) and HVDC Voltage Source Converter (VSC). The losses for each technology are calculated for wind farms with different ratings and various distances to shore. In addition, solutions with combinations of two and the three different transmission technologies are analyzed and compared. Based on this comparison, further analysis regarding the economical feasibility can be performed in order to determine the most economic solutions for the transmission system of an offshore wind farm. (author)

  6. Fault Locating in HVDC Transmission Lines Using Generalized Regression Neural Network and Random Forest Algorithm

    Directory of Open Access Journals (Sweden)

    M. Farshad

    2013-09-01

    Full Text Available This paper presents a novel method based on machine learning strategies for fault locating in high voltage direct current (HVDC transmission lines. In the proposed fault-location method, only post-fault voltage signals measured at one terminal are used for feature extraction. In this paper, due to high dimension of input feature vectors, two different estimators including the generalized regression neural network (GRNN and the random forest (RF algorithm are examined to find the relation between the features and the fault location. The results of evaluation using training and test patterns obtained by simulating various fault types in a long overhead transmission line with different fault locations, fault resistance and pre-fault current values have indicated the efficiency and the acceptable accuracy of the proposed approach.

  7. A novel protection method for VSC-HVDC transmission lines using single-end zero-mode current%利用零模电流的VSC-HVDC输电线路单端量保护原理研究

    Institute of Scientific and Technical Information of China (English)

    宋国兵; 冉孟兵; 靳幸福; 齐倩; 刘甜; 万青

    2014-01-01

    电压源换流器型直流输电(Voltage Source Converter HVDC,VSC-HVDC)控制系统复杂,故障承受能力差,研究适用于VSC-HVDC系统的高性能保护十分必要。分析了三相两电平VSC-HVDC系统的结构特性及VSC-HVDC系统的零模网络,并在此基础上提出了一种单端电气量保护。该方法仅需单端电流量,对直流线路一端正负极电流之和进行积分得到零模电流,根据零模电流的幅值大小可以判断出区内单极故障,适用于正负极对称运行的三相两电平 VSC-HVDC系统。算法简单可行,在时域进行,计算量小,对采样率要求低。利用PSCAD搭建VSC-HVDC系统进行仿真,仿真结果表明,该原理能够快速可靠地动作区内单极故障。%As the control system of Voltage Source Converter HVDC(VSC-HVDC) is very complex, its resistance to fault is poor. It’s necessary to do research on the protection of VSC-HVDC. This paper analyzes the structural characteristics and zero-mode network of VSC-HVDC, and proposes a single-end protection further. The proposed method needs only single-end zero-mode current which is obtained by integrating the sum of negative pole and positive pole currents. And the amplitude is used to distinguish internal single-pole-to-ground fault. The method applies to three-phase two-level VSC-HVDC system at positive and negative pole symmetrical operation status. The algorithm is very simple and implemented in time domain, needs fewer amount of computations, and its sampling frequency is lower. The PSCAD is used for fault simulation. Simulation results show that the proposed protection principle can find the internal single-pole-to-ground fault reliably and rapidly.

  8. Protection Principle for HVDC Transmission Lines Based on Fault Component of Voltage and Current%基于电压和电流突变量的高压直流输电线路保护原理

    Institute of Scientific and Technical Information of China (English)

    邢鲁华; 陈青; 付兆远; 高湛军; 于春光

    2012-01-01

    A new main protection principle is presented for high voltage direct current(HVDC) transmission lines.The principle is based on the variation characteristics of fault component of voltage and current,together with an indepth research on the transients caused by internal faults,external faults and lightning disturbances.By a set threshold for the ratio of amplitudes of the fault components of voltage at the same side relay location on bipolar lines,faults outside HVDC lines can be excluded,and the fault line can be distinguished.The polarities of the fault component of currents at the ends of the fault line are different for internal faults,while are the same for external faults.Accordingly,internal faults and external faults can be distinguished.Simulation results based on PSCAD/EMTDC for a practical HVDC transmission system demonstrate that the fault line can be rapidly selected and internal faults and external faults can be distinguished by the protection under bipolar neutral grounding at both ends mode.Lightning disturbances can be excluded by the proposed criterion.The protection criterion can move accurately for faults with high transition resistance and lightning induced faults,and can be also applied under one pole with 70% voltage and one pole with total voltage operation mode,anti-way power delivery operation mode,monopolar metallic return operation mode and one pole with maintenance outage.The calculation requirement of the protection criterion can be satisfied with sampling frequency in the range of 10~100 kHz.%在对高压直流输电线路区内、外故障和雷击等暂态过程研究的基础上,提出了一种基于电压、电流突变量变化特征的高压直流输电线路主保护原理。该原理对两极线路同侧保护安装处测得的电压突变量幅值的比值设定阈值,选出故障极;利用故障线路两端电流突变量的极性在线路保护区内故障时相异、在区外故障时相同,区分线路上保护区

  9. 电流激励下 HVDC 用电容器噪声辐射比研究%Study of noise radiation ratio of the capacitor for HVDC transmission system under current excitation

    Institute of Scientific and Technical Information of China (English)

    甘林; 刘夫云; 伍建伟; 邓勇

    2015-01-01

    The test method of noise radiation ratio of capacitor under current excitation is put forward . T hen the noise ratio measuring system in semi‐anechoic room is established based on the theoretical a‐nalysis of the characteristics of capacitor noise radiation .The capacitor noise radiation index curve un‐der current excitation is gotten by the method of vibration acoustic frequency response function .Final‐ly ,on the basis of capacitor noise radiation index curve ,the sound pressure value of capacitor surface is calculated and compared with the measured value to verify the accuracy of the method .%文章提出了电流激励下电容器噪声辐射比的测试方法,在理论分析电容器噪声辐射特性的基础上,建立了半消声室内测量电容器噪声辐射比的测试系统,在电流激励下采用振声频响函数法得到电容器的噪声辐射指数曲线。最后,依据电容器噪声辐射指数曲线计算得到电容器表面噪声声压值,并与实测噪声声压值进行对比,验证了方法的准确性。

  10. Transmission of Power to the Island Using HVDC (From Indian continent to Lakshadweep island

    Directory of Open Access Journals (Sweden)

    B. Vijayalakshmi

    2012-09-01

    Full Text Available HVDC transmission is more effective and economically cheaper where bulk power is to be transmitted over long distance. Hence the surplus power from a remote place can be exported to the needy place at cheaper rate. The HVDC system require only one transmission wire and the ground return or seawater can be used as an another line. The Lakshadweep Island is located at faraway place from the northeast part of India where the surplus power is available. The seawater for return path is available. The diesel for D.G set is transported from Indian mainland through ship where lot of economy is lost only for transportation. In this paper the transmission of HVDC from Indian mainland to Lakshadweep is analyzed at economically cheaper rate.

  11. Relative Localization in Wireless Sensor Networks for Measurement of Electric Fields under HVDC Transmission Lines

    Directory of Open Access Journals (Sweden)

    Yong Cui

    2015-02-01

    Full Text Available In the wireless sensor networks (WSNs for electric field measurement system under the High-Voltage Direct Current (HVDC transmission lines, it is necessary to obtain the electric field distribution with multiple sensors. The location information of each sensor is essential to the correct analysis of measurement results. Compared with the existing approach which gathers the location information by manually labelling sensors during deployment, the automatic localization can reduce the workload and improve the measurement efficiency. A novel and practical range-free localization algorithm for the localization of one-dimensional linear topology wireless networks in the electric field measurement system is presented. The algorithm utilizes unknown nodes’ neighbor lists based on the Received Signal Strength Indicator (RSSI values to determine the relative locations of nodes. The algorithm is able to handle the exceptional situation of the output permutation which can effectively improve the accuracy of localization. The performance of this algorithm under real circumstances has been evaluated through several experiments with different numbers of nodes and different node deployments in the China State Grid HVDC test base. Results show that the proposed algorithm achieves an accuracy of over 96% under different conditions.

  12. Relative localization in wireless sensor networks for measurement of electric fields under HVDC transmission lines.

    Science.gov (United States)

    Cui, Yong; Wang, Qiusheng; Yuan, Haiwen; Song, Xiao; Hu, Xuemin; Zhao, Luxing

    2015-02-04

    In the wireless sensor networks (WSNs) for electric field measurement system under the High-Voltage Direct Current (HVDC) transmission lines, it is necessary to obtain the electric field distribution with multiple sensors. The location information of each sensor is essential to the correct analysis of measurement results. Compared with the existing approach which gathers the location information by manually labelling sensors during deployment, the automatic localization can reduce the workload and improve the measurement efficiency. A novel and practical range-free localization algorithm for the localization of one-dimensional linear topology wireless networks in the electric field measurement system is presented. The algorithm utilizes unknown nodes' neighbor lists based on the Received Signal Strength Indicator (RSSI) values to determine the relative locations of nodes. The algorithm is able to handle the exceptional situation of the output permutation which can effectively improve the accuracy of localization. The performance of this algorithm under real circumstances has been evaluated through several experiments with different numbers of nodes and different node deployments in the China State Grid HVDC test base. Results show that the proposed algorithm achieves an accuracy of over 96% under different conditions.

  13. Control system of the physical simulation for the HVDC transmission system

    Science.gov (United States)

    Liu, Zheng; Huang, Tongyuan; Liu, Wei; Ai, Bing; Mou, Daohuai

    2007-12-01

    The intention of this paper is to present the control system of the physical simulation for the Three Gorges HVDC transmission system. It covers all essential control functions which are involved in the continuously working power flow control and power modulation including converter firing and pole current control. This system include two convert stations, They design the fault arbitrator for the dual-controller system based on fault-tolerant technology and figure-safety-comparing technology. The arbitrator can endure long working time with high reliability. Controller A and B not only works independent, but also can controlled by the master controller from CAN bus. At the same time, because the master controller is a industrial PC, we can easy adjust and enhance the functions. This characteristic is especially fit the physical simulation system.

  14. Power Flow Analysis of HVAC and HVDC Transmission Systems for Offshore WindParks

    DEFF Research Database (Denmark)

    da Silva, Filipe Miguel Faria; Castro, Rui

    2009-01-01

    As the onshore wind resource is running shorter, wind power promoters are paying attention to the offshore resources. As in most cases there is no load offshore, wind power must be transmitted to the main land. To do so, two options are available: HVAC and HVDC transmission systems. In this paper...... that HVAC solution is limited by the distance to shore and by the wind transmitted power. HVDC options do not show these limitations, but are more expensive and more delicate to deal with, because there is a lack of operational experience, so far....

  15. Modern Travelling Wave Based Fault Location Techniques for HVDC Transmission Lines

    Institute of Scientific and Technical Information of China (English)

    CHEN Ping; XU Bingyin; LI Jing; GE Yaozhong

    2008-01-01

    The modern travelling wave based fault location principles for transmission lines are ana-lyzed. In order to apply the travelling wave principles to HVDC transmission lines, the special tech-nical problems are studied. Based on this, a fault locating system for HVDC transmission lines is developed. The system can support modern double ended and single ended travelling wave princi-ples simultaneously, and it is composed of three different parts: travelling wave data acquisition and processing system, communication network and PC based master station. In the system, the fault generated transients are induced from the ground leads of the over-voltage suppression ca-pacitors of an HVDC line through specially developed travelling wave couplers.The system was applied to 500 Kv Gezhouba-Nanqiao(Shanghai)HVDC transmission line in China. Some field op- eration experiences are summarized, showing that the system has very high reliability and accu- racy,and the maximum location error is about 3 km(not more than 0.3% of the total line length). Obviously, the application of the system is successful, and the fault location problem has finally been solved completely since the line operation.

  16. Review of VSC HVDC Connection for Offshore Wind Power Integration

    DEFF Research Database (Denmark)

    Korompili, Asimenia; Wu, Qiuwei; Zhao, Haoran

    2016-01-01

    system is limited due to surplus charging current of the cables. The VSC HVDC transmission system has the ability to overcome the limitation and offers other advantages over the HVAC transmission system. This paper is to review the VSC HVDC transmission technology and its application for offshore wind...

  17. Reprint of “Performance analysis of a model-sized superconducting DC transmission system based VSC-HVDC transmission technologies using RTDS”

    Science.gov (United States)

    Dinh, Minh-Chau; Ju, Chang-Hyeon; Kim, Sung-Kyu; Kim, Jin-Geun; Park, Minwon; Yu, In-Keun

    2013-01-01

    The combination of a high temperature superconducting DC power cable and a voltage source converter based HVDC (VSC-HVDC) creates a new option for transmitting power with multiple collection and distribution points for long distance and bulk power transmissions. It offers some greater advantages compared with HVAC or conventional HVDC transmission systems, and it is well suited for the grid integration of renewable energy sources in existing distribution or transmission systems. For this reason, a superconducting DC transmission system based HVDC transmission technologies is planned to be set up in the Jeju power system, Korea. Before applying this system to a real power system on Jeju Island, system analysis should be performed through a real time test. In this paper, a model-sized superconducting VSC-HVDC system, which consists of a small model-sized VSC-HVDC connected to a 2 m YBCO HTS DC model cable, is implemented. The authors have performed the real-time simulation method that incorporates the model-sized superconducting VSC-HVDC system into the simulated Jeju power system using Real Time Digital Simulator (RTDS). The performance analysis of the superconducting VSC-HVDC systems has been verified by the proposed test platform and the results were discussed in detail.

  18. Hybrid Models of Alternative Current Filter for Hvdc

    Directory of Open Access Journals (Sweden)

    Ufa Ruslan A.

    2017-01-01

    Full Text Available Based on a hybrid simulation concept of HVDC, the developed hybrid AC filter models, providing the sufficiently full and adequate modeling of all single continuous spectrum of quasi-steady-state and transient processes in the filter, are presented. The obtained results suggest that usage of the hybrid simulation approach is carried out a methodically accurate with guaranteed instrumental error solution of differential equation systems of mathematical models of HVDC.

  19. HVDC: A key solution in future transmission systems

    Energy Technology Data Exchange (ETDEWEB)

    Heyman, Olof H.; Weimers, Lars; Bohl, Mie-Lotte

    2010-09-15

    With the transition of power grids, based on sustainable generation, HVDC is a key technology with new applications. This includes connection of remote wind parks and strengthening of existing AC grids. In addition, traditional applications, such as bulk hydropower transfer and interconnections between regions, play a major role in our transition to sustainable generation and the associated grids. The technology for regional grids with a limited number of nodes is already in place and commercial projects are commissioned. For extensive grids, development and verification are ongoing in parallel to industry standards being discussed in groups such as ENTSO-E and CIGRE.

  20. Mitigation of commutation failures in LCC-HVDC systems based on superconducting fault current limiters

    Science.gov (United States)

    Lee, Jong-Geon; Khan, Umer Amir; Lee, Ho-Yun; Lim, Sung-Woo; Lee, Bang-Wook

    2016-11-01

    Commutation failure in line commutated converter based HVDC systems cause severe damages on the entire power grid system. For LCC-HVDC, thyristor valves are turned on by a firing signal but turn off control is governed by the external applied AC voltage from surrounding network. When the fault occurs in AC system, turn-off control of thyristor valves is unavailable due to the voltage collapse of point of common coupling (PCC), which causes the commutation failure in LCC-HVDC link. Due to the commutation failure, the power transfer interruption, dc voltage drop and severe voltage fluctuation in the AC system could be occurred. In a severe situation, it might cause the protection system to block the valves. In this paper, as a solution to prevent the voltage collapse on PCC and to limit the fault current, the application study of resistive superconducting fault current limiter (SFCL) on LCC-HVDC grid system was performed with mathematical and simulation analyses. The simulation model was designed by Matlab/Simulink considering Haenam-Jeju HVDC power grid in Korea which includes conventional AC system and onshore wind farm and resistive SFCL model. From the result, it was observed that the application of SFCL on LCC-HVDC system is an effective solution to mitigate the commutation failure. And then the process to determine optimum quench resistance of SFCL which enables the recovery of commutation failure was deeply investigated.

  1. Mitigation of commutation failures in LCC–HVDC systems based on superconducting fault current limiters

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jong-Geon; Khan, Umer Amir; Lee, Ho-Yun; Lim, Sung-Woo; Lee, Bang-Wook, E-mail: bangwook@hanyang.ac.kr

    2016-11-15

    Commutation failure in line commutated converter based HVDC systems cause severe damages on the entire power grid system. For LCC–HVDC, thyristor valves are turned on by a firing signal but turn off control is governed by the external applied AC voltage from surrounding network. When the fault occurs in AC system, turn-off control of thyristor valves is unavailable due to the voltage collapse of point of common coupling (PCC), which causes the commutation failure in LCC–HVDC link. Due to the commutation failure, the power transfer interruption, dc voltage drop and severe voltage fluctuation in the AC system could be occurred. In a severe situation, it might cause the protection system to block the valves. In this paper, as a solution to prevent the voltage collapse on PCC and to limit the fault current, the application study of resistive superconducting fault current limiter (SFCL) on LCC–HVDC grid system was performed with mathematical and simulation analyses. The simulation model was designed by Matlab/Simulink considering Haenam-Jeju HVDC power grid in Korea which includes conventional AC system and onshore wind farm and resistive SFCL model. From the result, it was observed that the application of SFCL on LCC–HVDC system is an effective solution to mitigate the commutation failure. And then the process to determine optimum quench resistance of SFCL which enables the recovery of commutation failure was deeply investigated.

  2. Analysis on Electric Field Around HVAC-HVDC Hybrid Transmission Lines%Analysis on Electric Field Around HVAC-HVDC Hybrid Transmission Lines

    Institute of Scientific and Technical Information of China (English)

    LI Qian; LIU Jun-xiang; LI Hua; LIN Fu-chang

    2011-01-01

    As the transmission line corridors become more and more rare in China, it is now inevitable for people to construct HVAC-HVDC hybrid transmission lines. The research on the electric field around the transmission lines plays an important role in evaluating the electromagnetic environment nearby. However, few existing research now considered the mutual effect of HVAC-HVDC hybrid transmission lines. Thus, this research designed a program based on windows, which calculated the surface voltage gradient on the transmission lines and the electric field at ground level respectively. This research calculated the surface voltage gradient on the transmission lines by applying the improved method of successive images. For the electric field at ground level under AC transmission line, simula- tion charge method is used, while for the electric field at the ground level under DC transmission lines, deutsch as- sumption method is used. Comparing the results generated by the calculation with those in published literature, the program is reliable. Taking 500 kV transmission lines as an example, when considering the mutual effect of the HVAC-HVDC'lines, the amplitude of the surface voltage gradient will increase by about 10% and the amplitude of the electric field at ground level will increase by about 8%, making the mutual effect of the AC and DC lines unneglectable. Larger part of the electric field at ground level under hybrid lines is produced by the DC line. Thus, in order to control the electric field at ground level under hybrid lines, it should pay more attention on that produced by the DC line.

  3. Power Flow Analysis of HVAC and HVDC Transmission Systems for Offshore WindParks

    DEFF Research Database (Denmark)

    da Silva, Filipe Miguel Faria; Castro, Rui

    2009-01-01

    , the two options are analysed from a power flow point of view. The influence in the voltage regulation of the onshore connection busbar is investigated in a 57 bus test power system. The simulation results obtained for each one of the above mentioned transmission system configurations allow the conclusion......As the onshore wind resource is running shorter, wind power promoters are paying attention to the offshore resources. As in most cases there is no load offshore, wind power must be transmitted to the main land. To do so, two options are available: HVAC and HVDC transmission systems. In this paper...... that HVAC solution is limited by the distance to shore and by the wind transmitted power. HVDC options do not show these limitations, but are more expensive and more delicate to deal with, because there is a lack of operational experience, so far....

  4. Multilevel Modular Converter for VSC-HVDC Transmission Applications: Control and Operational Aspects

    DEFF Research Database (Denmark)

    Gnanarathna, Udana N.; Gole, Aniruddha M.; Chaudhary, Sanjay Kumar

    2010-01-01

    Control methods for a new class of converter, the multilevel modular converter (MMC), recently introduced for HVDC transmission are discussed. The paper discusses converter-level controls including firing pulse generation and capacitor voltage balancing. It also covers higher level controls...... for incorporating the converter into a larger power network, with a weak ac receiving end. The performance behavior is studied using electromagnetic transients simulation....

  5. A novel power control strategy of Modular Multi-level Converter in HVDC-AC hybrid transmission systems for passive networks

    DEFF Research Database (Denmark)

    Hu, Zhenda; Wu, Rui; Yang, Xiaodong;

    2014-01-01

    With the development of High Voltage DC Transmission (HVDC) technology, there will be more and more HVDC-AC hybrid transmission system in the world. A basic challenge in HVDC-AC hybrid transmission systems is to optimize the power sharing between DC and AC lines, which become more severe when...... supplying power for passive networks, as the surplus power can only flow back to power grids through the AC lines. To deal with this issue, it demands not only accurate system capability design but also flexible power control strategy of power converters in VSC-HVDC. This paper proposes a novel power...

  6. A Flexible Power Control Method of VSC-HVDC Link for the Enhancement of Effective Short-Circuit Ratio in a Hybrid Multi-Infeed HVDC System

    DEFF Research Database (Denmark)

    Liu, Yan; Chen, Zhe

    2013-01-01

    With the emerging use of voltage source converter high voltage direct current (VSC-HVDC) links, the hybrid multi-infeed HVDC (HMIDC) system that includes the line commutated converter (LCC) HVDC and the VSC-HVDC links is becoming a promising power transmission structure in the modern power systems....... To evaluate the contribution of the VSC-HVDC link on the voltage stability of HMIDC system, this paper proposes an effective short circuit ratio (ESCR) calculation method. Through the calculation, the voltage support capability of the VSC-HVDC link can be quantitatively represented by the ESCR. Furthermore......, based on the calculation results, a flexible power control strategy for the VSC-HVDC link is developed to provide maximum reactive power support under grid faults. The theoretical analysis of the HMIDC system is based on the Danish transmission grid, evaluated through PSCAD simulations under different...

  7. Cost and Benefit Analysis of VSC-HVDC Schemes for Offshore Wind Power Transmission

    Institute of Scientific and Technical Information of China (English)

    Sheng WANG; Chunmei FENG; An WEN; Jun LIANG

    2013-01-01

    Due to low load factors of wind power generation,it is possible to reduce transmission capacity to minimize the cost of transmission system construction.Two VSC-HVDC schemes for offshore wind farm,called the point to point (PTP) and DC mesh connections are compared in terms of the utilization of transmission system and its cost.A Weibull distribution is used for estimating offshore wind power generation,besides,the cross correlation between wind farms is considered.The wind energy curtailment is analyzed using the capacity output possibility table (COPT).The system power losses,costs of transmission investment and wind energy curtailment are also computed.A statistic model for the wind generation and transmission is built and simulated in MATLAB to validate the study.It is concluded that a DC mesh transmission can reduce the energy curtailment and power losses.Further benefit is achievable as the wind cross correlation between wind farms decreases.

  8. Low voltage fault ride through control in MMC-HVDC

    DEFF Research Database (Denmark)

    Chaudhary, S.; Teodorescu, R.; Rizadis, D.

    2017-01-01

    Modular multilevel converters (MMCs) are the latest converter topology for the high voltage high power applications like the high voltage dc (HVDC) transmission. This paper presents the response of an MMC-HVDC converter during grid faults. Recent grid code requirements specify reactive current...

  9. High-performance HVDC transmission over long distances; Hochleistungsuebertragung ueber grosse Entfernungen mit hochgespanntem Gleichstrom

    Energy Technology Data Exchange (ETDEWEB)

    Radtke, U. [PreussenElektra AG, Hannover (Germany)

    1998-12-31

    High-voltage DC transmission is a world-wide established technology for low-cost transmission of large amounts of electricity over long distances. Thanks to HVDC transmission, large amounts of electricity can now for the first time also be transmitted over long distances via ocean cable, something that cannot be done with AC power cables. HVDC transmission is independent of grid frequencies and can link grids of different frequency and different quality of frequency. Interconnected grids coupled via DC circuits can exploit additional technical and economic advantages such as mutual supply of power reserves, balancing of peak load, and modulation of active and reactive power. (orig.) [Deutsch] Die Hochspannungs-Gleichstromuebertragung (HGUe) ist eine weltweit etablierte Technik zur kostenguenstigen Uebertragung grosser elektrischer Leistungen ueber grosse Entfernungen. Sie schafft erstmals die Moeglichkeit, auch mittels Seekabel grosse Leistungen ueber Entfernungen zu uebertragen, die mit der Drehstromtechnik nicht moeglich sind. HGUeist unabhaengig von den Netzfrequenzen und kann Netze unterschiedlicher Frequenz und Frequenzguete miteinander verbinden. Ueber Gleichstromkreise gekuppelte Verbundnetze koennen zusaetzliche technische und wirtschaftliche Vorteile wie gegenseitige Bereitstellung von Kraftwerksreserven, Spitzenlastausgleich sowie Wirk- und Blindleistungsmodulation nutzt. (orig.)

  10. HVDC grids for offshore and supergrid of the future

    CERN Document Server

    Gomis-Bellmunt, Oriol; Liang, Jun

    2016-01-01

    Presents the advantages, challenges, and technologies of High Voltage Direct Current (HVDC) Grids This book discusses HVDC grids based on multi-terminal voltage-source converters (VSC), which is suitable for the connection of offshore wind farms and a possible solution for a continent wide overlay grid. HVDC Grids: For Offshore and Supergrid of the Future begins by introducing and analyzing the motivations and energy policy drives for developing offshore grids and the European Supergrid. HVDC transmission technology and offshore equipment are described in the second part of the book. The third part of the book discusses how HVDC grids can be developed and integrated in the existing power system. The fourth part of the book focuses on HVDC grid integration, in studies, for different time domains of electric power systems. The book concludes by discussing developments of advanced control methods and control devices for enabling DC grids.

  11. Second Order Cone Programming (SOCP) Relaxation Based Optimal Power Flow with Hybrid VSC-HVDC Transmission and Active Distribution Networks

    DEFF Research Database (Denmark)

    Ding, Tao; Li, Cheng; Yang, Yongheng

    2017-01-01

    The detailed topology of renewable resource bases may have the impact on the optimal power flow of the VSC-HVDC transmission network. To address this issue, this paper develops an optimal power flow with the hybrid VSC-HVDC transmission and active distribution networks to optimally schedule...... the generation output and voltage regulation of both networks, which leads to a non-convex programming model. Furthermore, the non-convex power flow equations are based on the Second Order Cone Programming (SOCP) relaxation approach. Thus, the proposed model can be relaxed to a SOCP that can be tractably solved...

  12. Numerical analysis of ionized fields associated with HVDC transmission lines including effect of wind

    Energy Technology Data Exchange (ETDEWEB)

    Li, X.

    1998-12-31

    The effects of corona discharge on the conductor surface of HVDC power transmission lines were studied. Corona discharges generate ion flow and can cause power losses and environmental concerns. Solving the problem of the ion flow field is difficult because of its nonlinearity and the effect of wind. The following two numerical algorithms were presented which address the problem associated with strong wind or bundled lines: (1) the finite element method (FEM) based optimization algorithm, and (2) the upwind FVM based relaxation algorithm. Both were successfully tested on a coaxial cylindrical configuration and on a unipolar line model in the presence of wind.

  13. Wind Farm Grid Integration Using VSC Based HVDC Transmission - An Overview

    DEFF Research Database (Denmark)

    Chaudhary, Sanjay Kumar; Teodorescu, Remus; Rodriguez, Pedro

    2008-01-01

    The paper gives an overview of HVAC and HVDC connection of wind farm to the grid, with an emphasis on Voltage Source Converter (VSC)-based HVDC for large wind farms requiring long distance cable connection. Flexible control capabilities of a VSC-based HVDC system enables smooth integration of wind...... farm into the power grid network while meeting the Grid Code Requirements (GCR). Operation of a wind farm with VSC-based HVDC connection is described....

  14. A Solid-State Fault Current Limiting Device for VSC-HVDC Systems

    Science.gov (United States)

    Larruskain, D. Marene; Zamora, Inmaculada; Abarrategui, , Oihane; Iturregi, Araitz

    2013-08-01

    Faults in the DC circuit constitute one of the main limitations of voltage source converter VSC-HVDC systems, as the high fault currents can damage seriously the converters. In this article, a new design for a fault current limiter (FCL) is proposed, which is capable of limiting the fault current as well as interrupting it, isolating the DC grid. The operation of the proposed FCL is analysed and verified with the most usual faults that can occur in overhead lines.

  15. Fast Decoupled Power Flow for Power System with High Voltage Direct Current Transmission Line System

    Directory of Open Access Journals (Sweden)

    Prechanon Kumkratug

    2010-01-01

    Full Text Available Problem statement: High voltage direct current transmission line system has been widely applied for control power flow in power system. The power flow analysis was the one of powerful tools by which the power system equipped was analyzed both for planning and operation strategies. Approach: This study presented the method to analyze power flow of power system consisted of HVDC system. HVDC was modeled as the complex power injections. The presented complex power injected was incorporated into the existing power flow program based on fast decoupled method. The presented method was tested on the multimachine power system. Results: The transmission line loss of the system with and without HVDC was compared. Conclusion: From the simulation results, the HVDC can reduce transmission line loss of power system.

  16. 模块化多电平变流器HVDC输电系统控制策略%Control Strategy of Modular Multilevel Converters Based HVDC Transmission

    Institute of Scientific and Technical Information of China (English)

    赵岩; 胡学浩; 汤广福; 贺之渊

    2011-01-01

    This paper built an electromagnetic transient mathematical model of modular multilevel converters (MMCs) and dynamic model of DC voltage in high voltage direct current (HVDC) transmission that adopts MMC as converter. Based on it, the dynamic characteristic of DC voltage in HVDC transmission was analyzed, and HVDC control system parameters coordinated design principles and its algorithm were proposed. Finally, the correctness of proposed submodule capacitor voltage balancing scheme, MMC based HVDC control system parameters coordinated design principles and its algorithm were verified by digital simulation based on PSCAD/EMTDC.%建立模块化多电平变流器(modular multilevel converters,MMCl的电磁暂态数学模型以及采用MMC为变流器的高压直流输电系统(high voltage direct current,HVDC)直流侧电压的动态数学模型。在此基础上,分析HVDC系统的直流侧电压动态特性,给出HVDC控制器参数协调设计原则和算法。最后,基于PscAD/EMTDc的数字仿真结果证明了所提出的HVDC控制系统参数协调设计原则和算法的正确性。

  17. Electromechanical Transient Modeling and Simulation for Voltage Source Converter Based HVDC Power Transmission%VSC-HVDC机电暂态仿真建模及仿真

    Institute of Scientific and Technical Information of China (English)

    刘昇; 徐政; 唐庚; 华文; 薛英林

    2013-01-01

    Based on the fundamental frequency mathematical model of VSC-HVDC power transmission in d-q rotating dq rotary coordinate system, the electromechanical transient mathematical equations of VSC-HVDC power transmission are summarized, afterwards a electromechanical transient model for VSC-HVDC power transmission is achieved based on user-defined function of PSS/E and the achieved model is compared with the precise electromagnetic transient model for VSC-HVDC power transmission in PSCAD, and simulation results show that the steady state power flows from the two models are very similar and their dynamic characteristics are highly consistent each other, thus the effectiveness and accuracy of the achieved electromechanical transient model for VSC-HVDC power transmission are verified. Finally, using the achieved model the application of VSC-HVDC power transmission in actual large-scale multi-infeed HVDC power transmission system is researched, and research results show that using VSC-HVDC power transmission technology the commutation failure occurred in traditional HVDC power transmission system can be radically resolved.%  以VSC-HVDC在dq旋转坐标系下的基频数学模型为基础,总结了 VSC-HVDC 的机电暂态数学方程。之后基于 PSS/E 自定义模型功能实现了 VSC-HVDC 机电暂态模型,并将该模型和PSCAD中VSC-HVDC电磁暂态精确模型进行了对比,仿真结果表明两者的稳态潮流十分接近,动态特性具有很好的一致性,从而验证了VSC-HVDC机电暂态模型的有效性和准确性。最后基于该模型对VSC-HVDC 在实际大规模多直流馈入系统中的应用进行了研究,结果表明 VSC-HVDC 从根本上解决了传统直流输电的换相失败问题。

  18. Research and development of HVDC remote control interface

    Science.gov (United States)

    Zhang, Zi-biao; Liu, Guo-ling; Geng, Zhan-xiao

    2013-03-01

    This paper introduces The development status quo of HVDC (high voltage direct current) power transmission project, analyzes the overall structure of RCI (remote control interface), puts forward the function design and the software realization. the communication message was accorded with the message defined in DL/T 634.5101-2002 / DL/T 634.5104-2002, the RCI could meet the requirement of the HVDC power transmission project ,which was approved, and there is guiding significance on the research of RCI of HVDC power transmission project..

  19. Calculation and measurement of electric field under HVDC transmission lines

    Science.gov (United States)

    Kasdi, A.; Zebboudj, Y.; Yala, H.

    2007-03-01

    A stable corona discharge in a two conductors-to-plane configuration is analysed in this paper. A linear biased probe, without end-effect, has been adapted to a linear geometry and is used for the first time to measure the ground-plane current density and electric field during the bipolar corona. The values of the electric field and the current density are maximum under the two coronating conductors and decrease when moving away from them. Furthermore, a hybrid technique is developed to obtain a general solution of the governing equations of the coupled space-charge and electric field problem. The technique is to use the finite-element method (FEM) to solve Poisson's equation, and the method of characteristic (MOC) to find the charge density from a current-continuity relation. The model avoids resorting to the Deutsch assumption. The computed values are in good agreement with experimental data.

  20. An Improvement VSC-HVDC Station in Thailand

    Directory of Open Access Journals (Sweden)

    Narin Watanakul

    2014-12-01

    Full Text Available The paper was to study design and improvement voltage source converter (VSC based HVDC long-distance transmission system around 110km between Thailand to Malaysia with rated 300MVA (±300 kV. This paper presents an application of an asynchronous back to back VSC-HVDC system, which uses multilevel converter a 7- level Diode-Clamped SPWM converters topology technique for the realization of HVDC system. The controller has been proposed by using PQ control and feedforward decoupled current control algorithm. The design and experimentally controllers of VSC in lab scaled test, MATLAB/Simulink program were performed VSC-HVDC transmission system, simulation in order to evaluate transient performance, can be controlled independently under two phase to ground faulted and three phases to ground faulted conditions. The system are used as a guideline for analysing and design of the data process control with the PQ-control HVDC system.

  1. Fault ride-through and grid support of permanent magnet synchronous generator-based wind farms with HVAC and VSC-HVDC transmission systems

    DEFF Research Database (Denmark)

    Liu, Hongzhi; Chen, Zhe

    2012-01-01

    This paper describes fault ride-through and grid support of offshore wind farms based on permanent magnet synchronous generator (PMSG) wind turbines connected to the onshore AC network through two alternative transmission systems: high voltage AC (HVAC) or high voltage DC (HVDC) based on voltage...... source converters (VSC). The proposed configurations of the PMSG-based offshore wind farm and VSC-based HVDC are given as well as their control strategies under both steady state and fault state. The PMSG-based offshore wind farm is integrated into a test power transmission system via either HVAC or VSC-HVDC...

  2. Analysis on Harmonic Instability in HVDC Transmission System%高压直流输电系统谐波失稳的分析

    Institute of Scientific and Technical Information of China (English)

    彭晨光; 褚优群; 马秀林

    2015-01-01

    针对HVDC(高压直流输电系统)存在的谐波失稳问题,通过计算电网动态过程中直流线路向整流、逆变两侧的等效阻抗,指出HVDC交直流两侧特定谐波的等效阻抗是研究谐波放大失稳的关键。根据PSCAD/EMTDC仿真软件中的HVDC电磁暂态模型,针对不同工况模拟计算。仿真结果表明,换流变铁心饱和导致了HVDC基频等效阻抗的实部减小甚至为负值,使其应对扰动的阻尼效果减小从而可能诱发HVDC谐波振荡失稳。%Aiming at harmonic instability in HVDC (high-voltage direct current) transmission system, the pa-per calculates equivalent impedance seen from the DC line to both converter and inverter sides in the power system transient state and indicates that equivalent impedance of particular harmonic at AC side and DC side of HVDC is the key of harmonic amplification instability research. Simulation and calculation is carried out in different operating conditions by use of HVDC electromagnetic transient model in PSCAD/EMTDC software. The simulation shows that the core saturation of the converter transformer leads to decrease or even negative value of real part of the converter DC side fundamental equivalent impedance, resulting further instability and oscillation in the system because of the damping reduction.

  3. 75 FR 69990 - Application for Presidential Permit; Northern Pass Transmission LLC

    Science.gov (United States)

    2010-11-16

    ... proposed international transmission line would originate at a high-voltage direct current (HVDC) converter... kilovolt (kV) HVDC overhead electric transmission line would extend southward in Province of Quebec for... Hampshire the proposed HVDC transmission line would continue southward for approximately 140 miles to...

  4. A Primary and Backup Protection Algorithm based on Voltage and Current Measurements for HVDC Grids

    OpenAIRE

    Abedrabbo, Mudar; Van Hertem, Dirk

    2016-01-01

    DC grids are susceptible to DC side faults, which lead to a rapid rise of the DC side currents. DC side faults should be detected in a very short time before fault currents cause damage to the system or equipment, e.g., exceed the maximum interruptible limits of DC circuit breaker. This paper presents a primary and backup protective data-based algorithm. The proposed algorithm depends on the local voltage and current measurements to detect and identify various kinds of faults in the HVDC grid...

  5. Novel Fault Diagnosis Scheme for HVDC System via ESO

    Institute of Scientific and Technical Information of China (English)

    YAN Bing-yong; TIAN Zuo-hua; SHI Song-jiao

    2007-01-01

    A novel fault detection and identification (FDI) scheme for HVDC (High Voltage Direct Current Transmission) system was presented. It was based on the unique active disturbance rejection concept, where the HVDC system faults were estimated using an extended states observer (ESO). Firstly, the mathematical model of HVDC system was constructed, where the system states and disturbance were treated as an extended state. An augment HVDC system was established by using the extended state in rectify side and converter side, respectively. Then, a fault diagnosis filter was established to diagnose the HVDC system faults via the ESO theory. The evolution of the extended state in the augment HVDC system can reflect the actual system faults and disturbances, which can be used for the fault diagnosis purpose. A novel feature of this approach is that it can simultaneously detect and identify the shape and magnitude of the HVDC faults and disturbance. Finally, different kinds of HVDC faults were simulated to illustrate the feasibility and effectiveness of the proposed ESO based FDI approach. Compared with the neural network based or support vector machine based FDI approach, the ESO based FDI scheme can reduce the fault detection time dramatically and track the actual system fault accurately. What's more important, it needs not do complex online calculations and the training of neural network so that it can be applied into practice.

  6. An Annotated Bibliography of HVDC Transmission and FACTS Devices, 1996-1997.

    Energy Technology Data Exchange (ETDEWEB)

    Litzenberger, Wayne H.; Varma, Rajiv K.; Flanagan, John D. [eds.

    1998-06-01

    This edition of the Annotated Bibliography of HVDC Transmission and FACTS Devices continues work begun in 1962 by the late Erik Bromberg, Bonneville Power Administration Librarian. His original bibliography covered the period 1932--1962. Subsequent editions were compiled by Bromberg, Val S. Lava, and Wayne Litzenberger, all of Bonneville Power Administration. Beginning with the 1991--1993 edition, the scope of the bibliography was expanded to include flexible ac transmission (FACTS) devices. This 1996--1997 edition also contains information for 1998. Preparation of the present edition took place primarily in May-June of 1998. All pertinent references have been included that were available to the editors at the time of preparation. Papers for the 1998 IEEE Winter and Summer Power Meetings and 1998 T and D Conference have been included. This edition contains the organizational affiliation of the first-named author as an aid to accessing the reference. Unfortunately, space limitations prevented the inclusion of the affiliations of all authors. Some minor editorial changes have been made to abstracts to ensure consistency in style and syntax.

  7. Dynamic Performance of a Back-to-Back HVDC Station Based on Voltage Source Converters

    Science.gov (United States)

    Khatir, Mohamed; Zidi, Sid-Ahmed; Hadjeri, Samir; Fellah, Mohammed-Karim

    2010-01-01

    The recent developments in semiconductors and control equipment have made the voltage source converter based high voltage direct current (VSC-HVDC) feasible. This new DC transmission is known as "HVDC Light or "HVDC Plus by leading vendors. Due to the use of VSC technology and pulse width modulation (PWM) the VSC-HVDC has a number of potential advantages as compared with classic HVDC. In this paper, the scenario of back-to-back VSC-HVDC link connecting two adjacent asynchronous AC networks is studied. Control strategy is implemented and its dynamic performances during disturbances are investigated in MATLAB/Simulink program. The simulation results have shown good performance of the proposed system under balanced and unbalanced fault conditions.

  8. 风电场向孤岛输电的VSC-HVDC Light的建模与仿真%Modelling and Simulation of VSC-HVDC Light for Electricity Transmission from Wind Farm to Solitary Island

    Institute of Scientific and Technical Information of China (English)

    谢海良; 王爱花; 赵君亮

    2014-01-01

    We introduced the operating principle and system of HVDC Light,which is based on the controlling of VSC. The simulation model of VSC-HVDC Light for electricity transmission from wind farm to solitary island by MATLAB is founded and simulated. The simulation result showed that system DC voltage value corresponds with the set value. The both ends of voltage value achieve coordination. Coordination control and self-banlancing transmission of active power are actualized. All quantities of states meet the theoretical value. The model accurately simulates the steady working condition of VSC-HVDC Light system,and offers the scientific basis for practical engineering.%介绍了以VSC控制为基础的HVDC Light的系统结构和工作原理,在MATLAB中创建了风电场向孤岛输电的VSC-HVDC Light系统仿真模型,并对其进行了稳态仿真研究。对仿真结果进行分析可知,系统直流电压基本稳定在给定的电压值,两端直流电压实现了协调配合,有功功率实现了协调控制和自动平衡传输,各状态量都符合理论值,模型准确模拟出了VSC-HVDC Light系统的稳态工作状况,为实际工程提供了科学的理论依据。

  9. Study on the Control Strategy of the Offshore Wind Energy Flexible Direct Current Transmission Using VSC-HVDC%采用VSC-HVDC的海上风电场柔性直流输电系统控制策略研究

    Institute of Scientific and Technical Information of China (English)

    蒋辰晖; 王志新; 吴定国

    2012-01-01

    Taking the three phase two-level voltage source current converter widely used in the actual offshore wind power transmission project as the research objective, this paper establishes a two—phase rotating dq system mathematical model in the two-phase rotating dq system by the coordinate transformation of the main converter circuit topology; and for the control system, uses the PI control method with a dual closed loop, and uses the current decoupling control to achieve the constant active/reactive power control which improves the system's dynamic performance and anti-jamming capability; and uses the space vector PWM modulation (which reduces the switching loss and harmonic content) for converting the current. The final matlab/Simulink simulation results and the 3.5 kW test show that the program has good control effects with voltage and current waveform stable, harmonic content low and response speedy. It is suitable for the offshore wind farm with the HVDC-Flexible system.%以实际应用于海上风电输电工程中的三相两电平电压源换流器为研究对象,通过对换流器主电路拓扑结构进行坐标变换,建立了便于解析的两相旋转dq坐标系下的数学模型;换流器控制系统采用了双闭环PI控制方法,并引入电流解耦控制,实现了一侧定有功、一侧定直流电压控制,提高了系统的动态性能和抗干扰能力;采用了SVPWM调制方式进行调制,有效地降低了谐波含量和开关损耗;采用Matlab/Simulink仿真,并搭建了3.5 kW试验验证平台.结果表明该方案控制效果良好,电压、电流波形稳定、谐波含量少且响应速度较快.因此,适用于海上风电场柔性直流输电系统.

  10. Voltage Balancing Method on Expert System for 51-Level MMC in High Voltage Direct Current Transmission

    Directory of Open Access Journals (Sweden)

    Yong Chen

    2016-01-01

    Full Text Available The Modular Multilevel Converters (MMC have been a spotlight for the high voltage and high power transmission systems. In the VSC-HVDC (High Voltage Direct Current based on Voltage Source Converter transmission system, the energy of DC link is stored in the distributed capacitors, and the difference of capacitors in parameters and charge rates causes capacitor voltage balance which affects the safety and stability of HVDC system. A method of MMC based on the expert system for reducing the frequency of the submodules (SMs of the IGBT switching frequency is proposed. Firstly, MMC with 51 levels for HVDC is designed. Secondly, the nearest level control (NLC for 51-level MMC is introduced. Thirdly, a modified capacitor voltage balancing method based on expert system for MMC-based HVDC transmission system is proposed. Finally, a simulation platform for 51-level Modular Multilevel Converter is constructed by using MATLAB/SIMULINK. The results indicate that the strategy proposed reduces the switching frequency on the premise of keeping submodule voltage basically identical, which greatly reduces the power losses for MMC-HVDC system.

  11. Contribution of VSC-HVDC to Frequency Regulation of Power Systems With Offshore Wind Generation

    DEFF Research Database (Denmark)

    Liu, Hongzhi; Chen, Zhe

    2015-01-01

    to the onshore system grid through voltage-source converter-based–high voltage direct current (VSC-HVdc) transmission systems. Due to the decoupling of VSC-HVdc and signal transmission delay, offshore wind farms may not be able to respond to the onshore grid frequency excursion in time and, consequently......, the stability and security of the power system will be put at risk, especially for those with high wind penetration. This paper proposes a coordinated control scheme to allow VSC-HVdc link to contribute to the system frequency regulation by adjusting its dc-link voltage. By means of this approach, the dc...... capacitors of VSC-HVdc are controlled to absorb or release energy so as to provide frequency support. To further enhance the system frequency response, the frequency support from VSC-HVdc is also finely coordinated with that from offshore wind farm according to the latency of offshore wind farm responding...

  12. A robust adaptive control with unmodeled dynamic for HVDC transmission systems

    Institute of Scientific and Technical Information of China (English)

    YAN Quan; LI Xing-yuan; WANG Lu; LIU Hong-chao; CHEN Shu-beng

    2006-01-01

    Utilizing the feature of quick response of HVDC to improve the performance of AC/DC system has become the emphasis to be researched.This paper introduces firstly the principle of the robust adaptive control of nonlinear systems with unmodeled dynamics,then developed the robust adaptive additional control of HVDC with unmodeled dynamics of generator in order to improve stability of power system.The additional control of HVDC with unmodeled dynamics only uses the local signals and its design is simple,furthermore it can obviously improve the stability of power system in different operational conditions.Experimental results using the presented concepts obtained on single machine infinite bus model are also included.These results prove the efficiency of the control scheme.The design process of controller provided a new idea to design controller by use of simplified model.

  13. Analysis and Simulation on Current Commutation of DC Transfer Switches in UHVDC Transmission Systems

    Institute of Scientific and Technical Information of China (English)

    PENG Chang; WEN Jialiang; MA Guohua; WANG Xiuhuan; LIU Zhigang; YU Kunshan

    2011-01-01

    The most severe working conditions of transfer switches in HVDC transmission systems identified as below: DC are For MRTB and GRTS, the most severe working condition is the failure of a single pole under operation mode. MRTB has to commutate the current from the ground return to metallic return. GRTS works in the contrary way.

  14. Optimizing the performance of a VSC HVDC control system

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Mau Cuong; Rudion, Krzystof; Styczynski, Zbigniew Antoni [Magdeburg Univ. (Germany). Chair for Electric Power Networks and Renewable Energy Sources

    2011-07-01

    This paper deals with the optimization of the parameters in the various control loops of a voltage source converter based high voltage direct current (VSC HVDC) transmission system connected to a doubly fed induction generator (DFIG) based wind farm. These control loops include a number of proportional-integral (PI) controllers. The performance of VSC HVDC depends on the parameters of these PI controllers. In this paper, the control strategy of each converter of the VSC HVDC is first introduced to investigate a VSC HVDC transmission system that transfers DFIG wind power over a long distance. Secondly, the optimization process, based on the simplex method which is proposed in the literature, is applied with the initial values of the PI controller's parameters, which are obtained by studying the classical frequency response of the open-loop transfer function of the VSC HVDC. The objective is to simultaneously minimize the weighted sum of the integral of the time absolute-error products (ITAE) of the AC voltage, reactive power, DC voltage and inner current controllers of both VSC stations. The effectiveness of the optimized parameters is assessed in the field of requirements of the VSC HVDC control system as mentioned above during voltage down to zero to reduce the generated power from wind farm. (orig.)

  15. Non-Pilot Protection of the HVDC Grid

    Science.gov (United States)

    Badrkhani Ajaei, Firouz

    This thesis develops a non-pilot protection system for the next generation power transmission system, the High-Voltage Direct Current (HVDC) grid. The HVDC grid protection system is required to be (i) adequately fast to prevent damages and/or converter blocking and (ii) reliable to minimize the impacts of faults. This study is mainly focused on the Modular Multilevel Converter (MMC) -based HVDC grid since the MMC is considered as the building block of the future HVDC systems. The studies reported in this thesis include (i) developing an enhanced equivalent model of the MMC to enable accurate representation of its DC-side fault response, (ii) developing a realistic HVDC-AC test system that includes a five-terminal MMC-based HVDC grid embedded in a large interconnected AC network, (iii) investigating the transient response of the developed test system to AC-side and DC-side disturbances in order to determine the HVDC grid protection requirements, (iv) investigating the fault surge propagation in the HVDC grid to determine the impacts of the DC-side fault location on the measured signals at each relay location, (v) designing a protection algorithm that detects and locates DC-side faults reliably and sufficiently fast to prevent relay malfunction and unnecessary blocking of the converters, and (vi) performing hardware-in-the-loop tests on the designed relay to verify its potential to be implemented in hardware. The results of the off-line time domain transients studies in the PSCAD software platform and the real-time hardware-in-the-loop tests using an enhanced version of the RTDS platform indicate that the developed HVDC grid relay meets all technical requirements including speed, dependability, security, selectivity, and robustness. Moreover, the developed protection algorithm does not impose considerable computational burden on the hardware.

  16. Simulative Study into the Development of a Hybrid HVDC System Through a Comparative Research with HVAC: a Futuristic Approach

    Directory of Open Access Journals (Sweden)

    R. S. Narayan

    2017-06-01

    Full Text Available High Voltage Direct Current Transmission (HVDC is considered a better solution for bulk long distance transmissions. The increased use of HVDC is a result of its advantages over the HVAC systems and especially of its fault stability nature. A better solution is proposed by using a Voltage Source Controlled–HVDC as one of the infeed for the Multi-Infeed HVDC (MIDC or MI-HVDC systems. The main advantage with the VSC converter is its flexible power control which enhances the stability of the MIDC systems. In this paper, the behavior of an HVDC system is compared with that of an HVAC during faults. A Hybrid HVDC system that includes a LCC as a rectifier unit and a VSC converter as the inverter is being proposed. It is considered suitable for MIDC systems and particularly for supplying a weak AC system. The performance of the system during steady state and transient conditions for all the proposed topologies including HVDC, HVAC and Hybrid HVDC are studied in MATLAB/SIMULINK. All of the proposed control strategies are evaluated via a series of simulation case studies.

  17. A Two-Dimensional Cloud Model for Condition Assessment of HVDC Converter Transformers

    Directory of Open Access Journals (Sweden)

    Linjie Zhao

    2012-01-01

    Full Text Available Converter transformers are the key and the most important components in high voltage direct current (HVDC power transmission systems. Statistics show that the failure rate of HVDC converter transformers is approximately twice of that of transformers in AC power systems. This paper presents an approach integrated with a two-dimensional cloud model and an entropy-based weight model to evaluate the condition of HVDC converter transformers. The integrated approach can describe the complexity of HVDC converter transformers and achieve an effective assessment of their condition. Data from electrical testing, DGA, oil testing, and visual inspection were chosen to form the double-level assessment index system. Analysis results show that the integrated approach is capable of providing a relevant and effective assessment which in turn, provides valuable information for the maintenance of HVDC converter transformers.

  18. The impact of HVDC innovations on the power industry

    OpenAIRE

    Stenberg, Nikolaos

    2013-01-01

    The purpose of this thesis is to examine the potential impact of High Voltage Direct Current (HVDC) innovations on the power industry. A short historical review is provided on the so-called ‘War of the Currents’, which has placed alternating current (AC) as the dominant platform for power transmission. The revival of DC in high voltage transmission is here examined as a reverse salient, as various indicators show that the role of HVDC in the power industry seems to be constantly growing. In t...

  19. The impact of HVDC innovations on the power industry

    OpenAIRE

    Stenberg, Nikolaos

    2013-01-01

    The purpose of this thesis is to examine the potential impact of High Voltage Direct Current (HVDC) innovations on the power industry. A short historical review is provided on the so-called ‘War of the Currents’, which has placed alternating current (AC) as the dominant platform for power transmission. The revival of DC in high voltage transmission is here examined as a reverse salient, as various indicators show that the role of HVDC in the power industry seems to be constantly growing. In t...

  20. HVDC Connected Offshore Wind Power Plants: Review and Outlook of Current Research

    DEFF Research Database (Denmark)

    Glasdam, Jakob Bærholm; Zeni, Lorenzo; Gryning, Mikkel

    2013-01-01

    these challenges through three coordinated PhD projects in close collaboration with leading academia within the field. The overall goal of these projects is to acquire indepth knowledge of relevant operating phenomena in the offshore OWPP grid, rich with power electronics devices (PEDs) such as the HVDC...... of the projects will be developed and validated models of e.g. the HVDC system, methodologies for assessment of control system stability and fault identification in implemented control system....

  1. HVDC Connected Offshore Wind Power Plants: Review and Outlook of Current Research

    DEFF Research Database (Denmark)

    Glasdam, Jakob; Zeni, Lorenzo; Gryning, Mikkel

    2013-01-01

    these challenges through three coordinated PhD projects in close collaboration with leading academia within the field. The overall goal of these projects is to acquire in-depth knowledge of relevant operating phenomena in the offshore OWPP grid, rich with power electronics devices (PEDs) such as the HVDC...... of the projects will be developed and validated models of e.g. the HVDC system, methodologies for assessment of control system stability and fault identification in implemented control system....

  2. Direct current power delivery system and method

    Science.gov (United States)

    Zhang, Di; Garces, Luis Jose; Dai, Jian; Lai, Rixin

    2016-09-06

    A power transmission system includes a first unit for carrying out the steps of receiving high voltage direct current (HVDC) power from an HVDC power line, generating an alternating current (AC) component indicative of a status of the first unit, and adding the AC component to the HVDC power line. Further, the power transmission system includes a second unit for carrying out the steps of generating a direct current (DC) voltage to transfer the HVDC power on the HVDC power line, wherein the HVDC power line is coupled between the first unit and the second unit, detecting a presence or an absence of the added AC component in the HVDC power line, and determining the status of the first unit based on the added AC component.

  3. HVDC-System-Interaction Assessment through Line-Flow Change-Distribution Factor and Transient-Stability Analysis at Planning Stage

    Directory of Open Access Journals (Sweden)

    Sungchul Hwang

    2016-12-01

    Full Text Available Many of the recent projects for new transmission line have considered the high-voltage direct current (HVDC system, owing to the many advantages of the direct current (DC system. The most noteworthy advantage is that a cable can serve as a substitute for the overhead transmission line in residential areas; therefore, the HVDC system application is increasing, and as the number of DC systems in the power system increases, the interaction assessment regarding the HVDC system gains importance. An index named multi-infeed interaction factor (MIIF is commonly used to estimate the interaction between power converters; however, the HVDC system is composed of two converters and a transmission line. The MIIF represents the interaction between the rectifiers and inverters, but not for the whole system. In this work, a method to assess the interaction of the whole system was therefore studied. To decide on the location of the new HVDC transmission system at the planning stage, in consideration of the interaction of the existing DC system, the line flow change distribution factor, according to the HVDC-transmission capacity change, was examined. Also, a power system transient -stability analysis was performed with different HVDC system locations, depending on the distribution factor. The simulation results indicate that when the factor is higher, two HVDC systems have a stronger interaction and are less stable in the transient state.

  4. 一种基于模块化多电平换流器的三极直流输电系统%A Tripole HVDC Transmission System Based on Modular Multilevel Converters

    Institute of Scientific and Technical Information of China (English)

    许烽; 徐政; 郑欢; 唐庚; 薛英林

    2014-01-01

    现有三极直流输电系统基于晶闸管换流器,存在一些与传统直流输电系统相似的固有缺陷。文中提出了一种改进系统:极3采用基于全桥子模块的模块化多电平换流器,极1和极2采用基于钳位双子模块的模块化多电平换流器。同时,提出了三极直流协调控制策略,并且为了抑制过渡阶段的暂态过电压,减小接地电流和功率波动,还提出了电压反向控制、电流维零控制和功率协调控制。采用PSCAD/EMTDC进行仿真验证,结果表明利用所提控制策略,三极直流输电系统能够获得较好的响应特性,在维持电容电压平衡的同时,能够抑制交直流间功率扰动和接地极电流波动。%The use of thyristor converters in existing tripole high voltage direct current (HVDC) transmission system suffers some inherent defects similar to those of the traditional HVDC transmission system.For this reason,this paper proposes an improved scheme which uses the modular multilevel converters(MMCs)based on full bridge sub-modules(FBSMs)to replace the thyristor converters in pole 3,and the converters in pole 1 and pole 2 are also replaced by the MMCs based on clamp double sub-modules (CDSMs).Meanwhile,the coordination control between the three poles is proposed.In order to suppress the transient overvoltage and minimize the grounding current and power fluctuation in the transition process,the voltage inverse control,power coordinated control and the control strategy of keeping current zero in pole 3 are also proposed. The performance of the proposed tripole HVDC transmission system is validated through time-domain simulation study in PSCAD/EMTDC.The results show that the tripole HVDC transmission system based on the proposed control strategy can achieve a satisfactory response characteristic,while maintaining the balance of capacitor voltage and minimizing the grounding current and power fluctuation.

  5. VSC-HVDC输电系统的性能分析%Performance Analysis of Voltage Source Converter Based HVDC Transmission System

    Institute of Scientific and Technical Information of China (English)

    姜建国; 颜廷阁

    2012-01-01

    VSC-HVDC is a new type of power transmission technology developed based on traditional HVDC. Aiming at the features of VSC-HVDC system, e. g. , good controllability, compact modular design and easy to construct multi-terminal DC systems, etc, the working principle and dynamic performance are described. Meanwhile, dynamic performance analysis on the faults of 100 kV and 200 MV VSC-HVDC transmission systems is investigated. The simulation results by using Matlab/Simulink verify that the system possesses good performance and effective decoupling control under active and reactive power variations and fault conditions.%电压源型高压直流输电( VSC-HVDC)技术是在传统直流输电基础上发展起来的一种新型输电技术.针对VSC-HVDC系统具有良好的可控性、紧凑的模块化设计、容易构成多端直流系统等特点,阐述了其工作原理及动态性能.同时,探讨了100 kV、200 MVVSC-HVDC输电系统故障的动态性能分析,并采用Matlab/Simulink进行了仿真试验.试验结果证实了该系统在有功与无功变化以及在故障条件下具有性能良好和解耦控制有效的特性.

  6. A new simplified adaptive control scheme for multi-terminal HVDC transmission systems

    Energy Technology Data Exchange (ETDEWEB)

    Meah, Kala [Electrical and Computer Engineering, York College of Pennsylvania, York, PA 17405 (United States); Ula, A.H.M. Sadrul [Electrical and Computer Engineering, University of Wyoming, Laramie, WY 82071 (United States)

    2010-05-15

    This paper proposes a new control scheme for multi-terminal HVDC (MTDC) systems to improve the performance during the system transients such as AC line faults. The new method is called parallel multi-proportional-integral (MPI) control scheme. This new control scheme provides wide range of controller parameters and has the ability to response quickly. To evaluate the performance of the proposed control scheme, a four-terminal HVDC system is considered with the detailed modeling of converters, commutation transformers, source impedances, line parameters, and filters. Simulation results from various transient conditions are compared between the proposed controller, the fuzzy logic-based auto-tuning PI controller, and the conventional fixed-parameter PI controller. The SimPowerSystems and the fuzzy logic toolboxes in the MATLAB/SIMULINK software package are used to conduct the simulations. Simulation results show that the MPI controller has better performance than the conventional fixed-parameter PI controller and has very similar responses compared to the fuzzy logic-based auto-tuning PI controller without any added complexity in controller design procedure for a MTDC system. (author)

  7. Interconnection of the power systems of the far east by using line HVDC transmission

    Directory of Open Access Journals (Sweden)

    Ilya Dydchenko

    2014-04-01

    Full Text Available The possibility of the interconnection continental part of the Russian Far East with the energy systems of Sakhalin and Japan. Indicate the technical possibility of this decision. The comparative analysis of the prospects for the construction of transmission lines of AC and DC. Proved the advantage of applying the lines of direct current for the interconnection of the Far East.

  8. HVDC System Stability – Analysis, Monitoring and Control in Wide Area Power Systems

    OpenAIRE

    Kuehn, Walter; Vanfretti, Luigi; Fischer, W.

    2014-01-01

    To a great extent future electric power systems will use HVDC technologies, based on either current sourced or voltage sourced converters (CSC, resp. VSC). Both technologies have their merits and range of applications being connected to technical capabilities, costs and operational properties and performance. Voltage stability is an important issue in classical CSC-based HVDC systems, while voltage stability and angle stability (both transmission angle and rotor angle) are of concern in VSC-H...

  9. Steady-state operational range evolution from a two-terminal to a multiterminal HVDC transmission system

    DEFF Research Database (Denmark)

    Irnawan, Roni; Silva, Filipe Miguel Faria da; Bak, Claus Leth;

    2017-01-01

    DC grids are anticipated to grow organically with one possible initial configuration being formed by interconnecting an additional HVDC converter into an existing shore-to-shore (StS) HVDC link. In order to ensure the performance of this MTDC system, the DC voltage at each converter terminal within...

  10. 基于小波变换的直流输电系统电磁暂态过程研究%Study on Electromagnetic Transient Process for HVDC Transmission System Based on Wavelet Transform

    Institute of Scientific and Technical Information of China (English)

    宋志明

    2011-01-01

    In order to perfect the protection system of HVDC transmission line, and to study electromagnetic transient process for HVDC (High Voltage Direct Current) transmission system, the lightning stroke flashover model and HVDC transmission system model are built by adopting PSCAD/EMTDC, in which the lightning stroke flashover model include transmission line, transmission tower, insulator string etc. Transient processes, such as the effect of lightning stroke at different positions on HVDC system, the typical fault occurring in both internal and external protection section of HVDC system, the influence of fault electrode on health electrode in the mode of two electrodes, are simulated. The decomposition analysis of signals are carried out by wavelet transform, and the different transient characteristics showing whether lightning stroke results in faults or not is found out. In addition, the characteristic signals that can represent different types of faults are analyzed, and the measures to avoid the interference of faulty electrode on non-faulty electrode for the operation mode of two electrodes are given. The results show that the study on electromagnetic transient process has important practical significance for the operation reliability of protection system and the security control of HVDC transmission line.%为完善直流输电线路的保护系统,以高压直流输电系统暂态过程为研究对象,采用PSCAD分别建立了高压直流输电系统(包括线路、杆塔、绝缘子串等)落雷闪络模型和直流输电系统模型;仿真了线路不同位置遭受雷击情况对直流输电系统的影响,直流线路保护区内外发生典型故障、双极运行模式下故障极对健全极的影响等多个暂态过程;利用小波变换进行信号分解分析,寻找出能够表征线路落雷导致系统故障或不致系统故障的明显暂态特点,分析能够体现不同类型故障的特征信号以及双极运行工况下,消除故障极对

  11. Stability Enhancement of Power System by Controlling Hvdc Power Flow through the Same Ac Transmission Line

    Directory of Open Access Journals (Sweden)

    P. Upendra Kumar

    2014-04-01

    Full Text Available Long extra high voltage (EHV ac lines cannot be loaded to their thermal limits in order to keep sufficient margin against transient instability. With the scheme proposed in this paper, it is possible to load these lines very close to their thermal limits. The conductors are allowed to carry usual ac along with dc superimposed on it. The added dc power flow does not cause any transient instability. This paper presents the feasibility of converting a double circuit ac line into composite ac–dc power transmission line to get the advantages of parallel ac–dc transmission to improve stability and damping out oscillations. Simulation and experimental studies are carried out for the coordinated control as well as independent control of ac and dc power transmissions. No alterations of conductors, insulator strings, and towers of the original line are needed. Substantial gain in the loadability of the line is obtained. Master current controller senses ac current and regulates the dc current orders for converters online such that conductor current never exceeds its thermal limit. The present paper is implemented by using MATLAB/SIMULINK.

  12. Power system integration of VSC-HVDC connected offshore wind power plants

    DEFF Research Database (Denmark)

    Zeni, Lorenzo; Kjær, Philip Carne

    . The benefits of not prioritising active power during current-limited operation are demonstrated on a simple system and the possible implications on the control of a WPP potentially connected behind the HVDC converter are discussed. Active power balance control is the second service being analysed......This report presents an overview of challenges and solutions for the integration into the power system of offshore wind power plants (WPPs) connected to onshore grids through a voltage-source converter based high voltage direct current (VSC-HVDC) transmission system. Aspects that are touched upon...... are (i) principles for the control of offshore alternating current (AC) networks behind offshore VSC-HVDC converters, (ii) power system services that could be featured by VSC-HVDC connected WPPs and (iii) clustering of multiple WPPs to co-ordinately provide desired control actions. After a brief...

  13. Operational characteristics analysis of a 8 mH class HTS DC reactor for an LCC type HVDC system

    Energy Technology Data Exchange (ETDEWEB)

    Kim, S. K.; Go, B. S.; Dinh, M. C.; Park, M.; Yu, I. K. [Changwon National University, Changwon (Korea, Republic of); Kim, J. H. [Daejeon University, Daejeon (Korea, Republic of)

    2015-03-15

    Many kinds of high temperature superconducting (HTS) devices are being developed due to its several advantages. In particular, the advantages of HTS devices are maximized under the DC condition. A line commutated converter (LCC) type high voltage direct current (HVDC) transmission system requires large capacity of DC reactors to protect the converters from faults. However, conventional DC reactor made of copper causes a lot of electrical losses. Thus, it is being attempted to apply the HTS DC reactor to an HVDC transmission system. The authors have developed a 8 mH class HTS DC reactor and a model-sized LCC type HVDC system. The HTS DC reactor was operated to analyze its operational characteristics in connection with the HVDC system. The voltage at both ends of the HTS DC reactor was measured to investigate the stability of the reactor. The voltages and currents at the AC and DC side of the system were measured to confirm the influence of the HTS DC reactor on the system. Two 5 mH copper DC reactors were connected to the HVDC system and investigated to compare the operational characteristics. In this paper, the operational characteristics of the HVDC system with the HTS DC reactor according to firing angle are described. The voltage and current characteristics of the system according to the types of DC reactors and harmonic characteristics are analyzed. Through the results, the applicability of an HTS DC reactor in an HVDC system is confirmed.

  14. New Progress on Self-Reliant Innovation of HVDC Technology

    Institute of Scientific and Technical Information of China (English)

    Li Yan; Li Xiaolin; Rao Hong; Zhao Jie; Yang Xiaoli

    2009-01-01

    @@ It is an important direction for China's power industry to master the design and the equipment manufacturing core technology of large-capacity HVDC power transmission systems,and to form the sustainable development capability.Before the self-reliant innovation of Guiguang Ⅱ HVDC project in 2004,the deficiency of the HVDC core technology in China was shown in the following aspects.

  15. 直流跨区互联电网发输电计划模型与方法%Model and Methods of Generation and Transmission Scheduling of Inter-regional Power Grid via HVDC Tie-line

    Institute of Scientific and Technical Information of China (English)

    王斌; 夏叶; 夏清; 张慧玲; 韩红卫

    2016-01-01

    直流跨区输电为大范围资源优化配置和清洁能源跨区消纳提供了高效的物理平台。充分利用区域间电源结构互济、负荷特性互补的优势,可以有效挖掘电力资源跨区协调优化潜力、提升电网清洁能源消纳能力。为此,文中在兼顾现有国(分)、省两级调度模式的基础上,提出了以直流联络线功率为协调变量,区内优化、跨区协调的直流跨区互联电网发输电计划模式;建立了考虑直流调整灵活性、直流联络线日交易电量、联络线运行功率曲线阶梯化等实际运行要求的发输电计划模型;提出了以直流功率为引导变量的跨区边际机组识别方法,解决了上述大规模混合整数规划模型的求解效率问题。基于省网实际负荷曲线进行算例分析,验证了所提模式、模型、方法的有效性。%A highly efficient physical platform is provided by inter-regional high voltage direct current (HVDC) tie-line for large-range cross-region clean energy accommodation and resources allocation.The cross-regional coordinative optimization potential of power resources can be tapped and the accommodation capability of clean energy improved if complementary characteristics of power supply structure and system load of each region are well utilized.To this end,a generation and transmission scheduling mode of inter-regional power grid via HVDC tie-line is proposed based on the two-level “state-province" system operation pattern.In this mode,the transmission power of HVDC tie-line is viewed as cross-regional coordinative variable while generator scheduling is optimized inside each region.A mathematical model of generation and transmission scheduling mode of inter-regional power grid via HVDC tie-line is developed with various practical operation constraints taken into account,including the HVDC flexible adjustment constraints,tie-line daily transaction energy limit and tie-line power profile stair

  16. An Assessment of Converter Modelling Needs for Offshore Wind Power Plants Connected via VSC-HVDC Networks

    DEFF Research Database (Denmark)

    Glasdam, Jakob; Zeni, Lorenzo; Hjerrild, Jesper

    2013-01-01

    Modular multilevel cascaded converter (MMCC) based high voltage direct current (HVDC) transmission is technically superior to other technologies, especially in case of connection of offshore wind power plants (OWPPs). Modelling challenges are faced by OWPP developers, who are not acquainted...... with detailed information regarding the internal behaviour of such complex devices. This paper presents an investigation of the modelling requirements of the MMCC HVDC system, based on comparison between simulation results using a detailed HVDC representation in PSCAD/EMTDC and two less detailed models realised...

  17. 基于CPS-SPWM调制方法的MMC-HVDC输电系统冗余保护策略研究%Redundancy protection strategy research of MMC-HVDC transmission system based on CPS-SPWM modulation method

    Institute of Scientific and Technical Information of China (English)

    胡益; 王晓茹; 胡柏玮

    2016-01-01

    子模块故障是模块化多电平换流器高压直流输电( MMC⁃HVDC )系统最常见故障之一。为保证子模块故障后MMC⁃HVDC系统能够稳定工作,本文首先对子模块故障后桥臂电流、桥臂间环流及直流侧电流的影响进行数学分析,确定了MMC子模块容错方案;然后将子模块冗余控制与带有电容均压控制和环流抑制控制的载波相移脉宽调制( CPS⁃SPWM )方法相结合,设计了基于电容电压平衡控制CPS⁃SPWM的冗余保护策略;最后在PSCAD/EMTDC中搭建双端10电平的MMC⁃HVDC输电系统模型。通过对模型进行稳态仿真以及子模块故障时的暂态对比仿真,验证了本文所提出的冗余保护策略的正确性和有效性。%The sub⁃module failure is one of the most common faults in modular multilevel converter HVDC trans⁃mission systems. In order to ensure the MMC⁃HVDC system can work steadily when the sub⁃module was failure, the following steps are needed to be done. Firstly, a mathematical analysis for the influence of bridge arm current, circulation current and it’ s DC side current is made under the sub⁃module fault, so that the sub⁃module fault⁃toler⁃ant scheme is determined. Then, the sub⁃module redundancy control is combined with the CPS⁃SPWM modulation method which contains capacitor voltage balance control and circulation inhibitory control. The redundancy protec⁃tion strategy is designed which is based on the CPS⁃SPWM modulation method with capacitor voltage balance control method. Finally, a two⁃terminal 10⁃level MMC⁃HVDC transmission system model is established in PSCAD/EMT⁃DC. Through the steady state simulation and the comparison of sub⁃module fault transient simulation, the correct⁃ness and validity of redundancy protection strategy which is proposed in this paper are verified.

  18. Examination of fault ride-through methods for off-shore wind farms connected to the grid through VSC-based HVDC transmission

    Energy Technology Data Exchange (ETDEWEB)

    Karaagac, U.; Mahseredjian, J.; Saad, H. [Ecole Polytechnique de Montreal, QC (Canada); Jensen, S.; Cai, L. [REpower Systems AG, Hamburg (Germany)

    2012-07-01

    The fault ride-through (FRT) performance of offshore wind farms (OWFs) is a challenging task when the OWF is connected to the onshore ac grid through a voltage source converter (VSC) based HVDC transmission system. The injected power from the OWF cannot be reduced by the offshore VSC during onshore ac faults and this causes a fast increase in the dc network voltage. Without any special FRT method, the dc network voltage may increase up to intolerable levels and cause operation of dc overvoltage protection. This paper compares various FRT methods based on fast reduction of power generation in OWFs. In addition, this paper proposes an improved FRT method based on controlled voltage drop for output power reduction in OWFs. The proposed improvement reduces mechanical stress on the wind turbine (WT) drive train, and electrical stress on the insulated gate bipolar transistors (IGBTs) of the HVDC and doubly-fed induction generator (DFIG) converters. Practical onshore ac fault scenarios are simulated for an OWF composed of DFIG type WTs and connected to a practical ac grid through a point-to-point modular multilevel converter (MMC) based HVDC system. (orig.)

  19. Direct current in the future. HVDC better than a high-voltage alternating current cable; Gelijk in de toekomst. HVDC-verbonding beter dan hoogspanningskabel met wisselstroom

    Energy Technology Data Exchange (ETDEWEB)

    Van Velzen, T.

    2010-10-01

    For the development of a pan-European high-voltage grid the application of direct current (DC) technology is obvious. However, a series of incidents involving a link between the Netherlands and Norway raises questions about the reliability. An alternative conversion method seems more suited for a European supernetwork. DC transmission with insulated-gate bipolar transistor is the technology of the future. [Dutch] Voor de ontwikkeling van een pan-Europees hoogspanningsnet ligt toepassing van gelijkstroomtechnologie voor de hand. Een reeks incidenten met zo'n verbinding tussen Nederland en Noorwegen roept echter vragen op over de betrouwbaarheid. Een alternatieve conversietechniek lijkt echter geschikter voor een Europees supernet. Gelijkstroomtransmissie met 'insulated-gate bipolar' transistors is de techniek van de toekomst.

  20. VSC-HVDC Technology Suitable for Bulk Power Overhead Line Transmission%大容量架空线柔性直流输电关键技术及前景展望

    Institute of Scientific and Technical Information of China (English)

    徐政; 薛英林; 张哲任

    2014-01-01

    To make the voltage source converter based high voltage direct current (VSC-HVDC) system extend to long distance bulk power overhead line transmission is the inherent requirement of energy source distribution in China and future trend of power grid development. However, the challenges associated with the state-of-the-art VSC-HVDC system mainly include: a) difficulty to handle dc fault, b) less transmission capacity compared with the traditional HVDC systems, and c) difficulty to select grounding point. For the first challenge, this paper analyzes vulnerability of the existing topologies against dc faults, focusing on an overview of the topologies with dc fault ride-through capability. According to the characteristics of dc fault processing, these topologies can be divided into three basic types. Furthermore, advantages and defects of these typical topologies are discussed. For the second and third challenges, to achieve a high voltage and power level, a bipolar VSC-HVDC topology with assembly converter is proposed. In this topology, each pole consists of several basic converter units (BCU) in series or in parallel; between the positive pole and the negative pole is the neutral bus which is connected to the ground electrode. Furthermore, the advantages and shortcomings of the possible grounding modes are summarized. At last, according to the unidirectional energy flow characteristics of China, two basic VSC-HVDC structures are analyzed.%柔性直流输电技术(voltage source converter based high voltage direct current,VSC-HVDC)应用于远距离大容量架空线输电是实现我国能源资源优化配置的客观要求,也是电网技术发展的未来趋势。目前柔性直流输电技术扩展到架空线输电场合所面临的关键问题有:直流线路故障难以快速清除、输送容量难以与传统直流输电相媲拟、主接线方式和接地方式选择原则还没有定论等。针对问题1,分析现有工程所采用的拓扑结构

  1. HVDC Connected Offshore Wind Power Plants: Review and Outlook of Current Research

    DEFF Research Database (Denmark)

    Glasdam, Jakob; Zeni, Lorenzo; Gryning, Mikkel;

    2013-01-01

    This paper presents a state-of-the-art review on grid integration of large offshore wind power plants (OWPPs) using high voltage direct voltage (HVDC) for grid connection. The paper describes in detail selected challenges hereto and presents how DONG Energy Wind Power (DEWP) is addressing...... and the PED widely used in the wind turbine generators (WTGs). Challenges hereto include PED control system interaction (from a stability point of view), assessment of the quality of vendor supplied control systems and their robustness against e.g. short circuits and load rejection. Furthermore, the outcome...

  2. Adaptive Modulation for DFIG and STATCOM With High-Voltage Direct Current Transmission.

    Science.gov (United States)

    Tang, Yufei; He, Haibo; Ni, Zhen; Wen, Jinyu; Huang, Tingwen

    2016-08-01

    This paper develops an adaptive modulation approach for power system control based on the approximate/adaptive dynamic programming method, namely, the goal representation heuristic dynamic programming (GrHDP). In particular, we focus on the fault recovery problem of a doubly fed induction generator (DFIG)-based wind farm and a static synchronous compensator (STATCOM) with high-voltage direct current (HVDC) transmission. In this design, the online GrHDP-based controller provides three adaptive supplementary control signals to the DFIG controller, STATCOM controller, and HVDC rectifier controller, respectively. The mechanism is to observe the system states and their derivatives and then provides supplementary control to the plant according to the utility function. With the GrHDP design, the controller can adaptively develop an internal goal representation signal according to the observed power system states, therefore, to achieve more effective learning and modulating. Our control approach is validated on a wind power integrated benchmark system with two areas connected by HVDC transmission lines. Compared with the classical direct HDP and proportional integral control, our GrHDP approach demonstrates the improved transient stability under system faults. Moreover, experiments under different system operating conditions with signal transmission delays are also carried out to further verify the effectiveness and robustness of the proposed approach.

  3. Fast Protection Scheme for Overhead Transmission Lines of VSC-based HVDC Grid%柔性直流电网架空线路快速保护方案

    Institute of Scientific and Technical Information of China (English)

    王艳婷; 张保会; 范新凯

    2016-01-01

    The voltage source converter(VSC)-based high voltage direct current(HVDC)grid technology is an effective means for large-scale integration of clean energy.The fast DC line protection technology is one of the main challenges to HVDC grids. Based on the Zhangbei HVDC grid project,this paper proposes a fast protection scheme for overhead transmission lines of bipolar VSC-based HVDC grids equipped with DC circuit breakers.The protection is based on local measurements featuring fast response speed.The voltage gradient is used to detect faults rapidly,and the voltage derivative criterion is adopted to identify the protection zone in which the fault occurs thanks to the smoothing effect of the fault current limiter.And the faulty pole is identified according to the different propagation characteristics between the line mode and zero mode voltage,ensuring the selectivity of the protection as well as high reliability.The Zhangbei HVDC grid model is built in PSCAD/EMTDC and the performance of the proposed protection scheme is verified by simulation results of various fault conditions,as well as different operation modes of the HVDC grids.%基于柔性直流输电的直流电网技术,是大规模清洁能源接入电网的有效手段,直流电网快速线路保护是其面临的重要技术挑战之一。以国内计划建设的张北直流电网工程为背景,提出了一套适用于全网配置直流断路器、采用架空线输电的对称双极直流电网线路快速保护方案。保护仅利用单端信息进行故障判别,且保护数据窗短,满足速动性的要求;保护采用电压梯度快速检测故障,利用限流电抗器对故障电压信号的平滑作用实现故障区间的判别,并根据零模与一模电压传播特性的差异判定故障极,实现保护的选择性与高可靠性。结合直流电网的PSCAD模型,验证了所提出方案在不同故障情况下的保护性能,并分析了保护对运行方式改变的适应性。

  4. 直流输电系统强迫停运探讨%Discussion on forced outages of HVDC transmission system

    Institute of Scientific and Technical Information of China (English)

    朱韬析; 李娟; 王超; 陈为化

    2009-01-01

    There are many protection and monitoring functions in HVDC transmission system. Although the equipments are completely protected, the mal-operation is very difficult to be avoided. In this paper, based on the experiences of Tian-Guang HVDC transmission system, the forced outage and the protection and monitoring which would cause forced outage are introduced first, then the reason caused forced outages in operation in those years and its effect are analyzed. At last, combined with the safety of equipments and the reliability of power system, the improving suggestion to the protection and monitoring function in HVDC transmission system is discussed.%直流输电系统中设置了大量的保护、监视功能,但在确保设备安全的同时,也带来了容易误动的隐患.以天广直流输电系统为例,首先介绍了直流输电系统的强迫停运及可能引起强迫停运的保护监视功能,接着讨论了多年来运行中发生的强迫停运故障原因及故障时对设备的影响,最后综合考虑设备的安全和电网的稳定,对直流输电系统的保护、监视功能提出了改进建议.

  5. 柔性直流输电线路故障处理与保护技术评述%Comments on Fault Handling and Protection Technology for VSC-HVDC Transmission Lines

    Institute of Scientific and Technical Information of China (English)

    刘剑; 邰能灵; 范春菊; 黄文焘

    2015-01-01

    由于柔性直流输电系统调节方式和自身结构的特殊性,直流线路的故障电流具有上升速度快、峰值大的特点,极易损坏换流器件和设备绝缘,且柔性直流系统无法通过调节触发角实现故障自清除。因此,对直流线路故障处理和保护提出了更高要求。对于柔性直流线路故障,不仅需要快速且可靠的线路保护对故障进行识别,也需要相应的处理措施和手段对故障后的电流进行有效限制,以减少故障冲击电流对换流器件、直流线路自身以及系统的损害。基于柔性直流输电线路的故障特征,从直流线路故障电流抑制、减少故障影响、线路保护原理等方面,系统地介绍了国内、国外柔性直流输电线路故障处理与保护技术的现状和发展。重点分析了几种辅助电路、新型换流器拓扑和直流输电结构,以及直流断路器在处理直流线路故障方面的性能。探讨了目前柔性直流输电线路故障处理和保护亟须解决的关键问题以及未来进一步的研究方向。%Owing to the specific mode of regulation and structure of the voltage source converter-high voltage direct current (VSC-HVDC) transmission system,the DC line fault current is characterized by high increasing speed and great peak value. This is extremely susceptible to destruction of converter devices and damage to insulation of equipment.VSC-HVDC system cannot realize fault self-clearing by adjusting the firing angle.Therefore,higher requirements are made on protection and fault handling of DC transmission lines.For DC line faults,not only is reliable and fast protection needed for fault identification,but also corresponding control measures and circuit should be taken to limit the fault current and reduce the damage of the current to converter devices,the DC line itself and system.Based on the fault characteristics of VSC-HVDC transmission lines,the state of the art of DC line

  6. Improved Power Flow Algorithm for VSC-HVDC System Based on High-Order Newton-Type Method

    Directory of Open Access Journals (Sweden)

    Yanfang Wei

    2013-01-01

    Full Text Available Voltage source converter (VSC based high-voltage direct-current (HVDC system is a new transmission technique, which has the most promising applications in the fields of power systems and power electronics. Considering the importance of power flow analysis of the VSC-HVDC system for its utilization and exploitation, the improved power flow algorithms for VSC-HVDC system based on third-order and sixth-order Newton-type method are presented. The steady power model of VSC-HVDC system is introduced firstly. Then the derivation solving formats of multivariable matrix for third-order and sixth-order Newton-type power flow method of VSC-HVDC system are given. The formats have the feature of third-order and sixth-order convergence based on Newton method. Further, based on the automatic differentiation technology and third-order Newton method, a new improved algorithm is given, which will help in improving the program development, computation efficiency, maintainability, and flexibility of the power flow. Simulations of AC/DC power systems in two-terminal, multi-terminal, and multi-infeed DC with VSC-HVDC are carried out for the modified IEEE bus systems, which show the effectiveness and practicality of the presented algorithms for VSC-HVDC system.

  7. Grid-connection of large offshore windfarms utilizing VSC-HVDC: Modeling and grid impact

    DEFF Research Database (Denmark)

    Xue, Yijing; Akhmatov, Vladislav

    2009-01-01

    Utilization of Voltage Source Converter (VSC) – High Voltage Direct Current (HVDC) systems for grid-connection of large offshore windfarms becomes relevant as installed power capacities as well as distances to the connection points of the on-land transmission systems increase. At the same time......, the grid code requirements of the Transmission System Operators (TSO), including ancillary system services and Low-Voltage Fault-Ride-Through (LVFRT) capability of large offshore windfarms, become more demanding. This paper presents a general-level model of and a LVFRT solution for a VSC-HVDC system...... for grid-connection of large offshore windfarms. The VSC-HVDC model is implemented using a general approach of independent control of active and reactive power in normal operation situations. The on-land VSC inverter, which is also called a grid-side inverter, provides voltage support to the transmission...

  8. Coordinated Control Strategies of VSC-HVDC-Based Wind Power Systems for Low Voltage Ride Through

    Directory of Open Access Journals (Sweden)

    Xinyin Zhang

    2015-07-01

    Full Text Available The Voltage Source Converter-HVDC (VSC-HVDC system applied to wind power generation can solve large scale wind farm grid-connection and long distance transmission problems. However, the low voltage ride through (LVRT of the VSC-HVDC connected wind farm is a key technology issue that must be solved, and it is currently lacking an economic and effective solution. In this paper, a LVRT coordinated control strategy is proposed for the VSC-HVDC-based wind power system. In this strategy, the operation and control of VSC-HVDC and wind farm during the grid fault period is improved. The VSC-HVDC system not only provides reactive power support to the grid, but also effectively maintains the power balance and DC voltage stability by reducing wind-farm power output, without increasing the equipment investment. Correspondingly, to eliminate the influence on permanent magnet synchronous generator (PMSG-based wind turbine (WT systems, a hierarchical control strategy is designed. The speed and validity of the proposed LVRT coordinated control strategy and hierarchical control strategy were verified by MATLAB/Simulink simulations.

  9. 新型双馈入直流输电系统供电无源网络的运行特性研究%Operation Characteristic Research on Novel Double-Infeed HVDC System Supplying Passive Network

    Institute of Scientific and Technical Information of China (English)

    郭春义; 赵成勇; 王晶

    2012-01-01

    A novel double-infeed HVDC system, combining a conventional high voltage direct current transmission (HVDC) and voltage-source converter based HVDC (VSC-HVDC), is proposed in this paper for supplying an entirely passive AC network. The detailed model for starting HVDC using VSC-HVDC is provided and control strategies of the whole system are designed. Aiming to validate the steady state and dynamic performance of the double-infeed HVDC system, the process of starting HVDC using VSC-HVDC and the dynamic performance of double-infeed HVDC when three-phase to ground fault occurring at HVDC inverter side are investigated. PSCAD/EMTDC Simulation results show that, the proposed double-Infeed HVDC system can supply power to passive network and it also has favorable dynamic and fault-restoration performance.%提出由传统高压直流输电系统(HVDC)和电压源换流器高压直流输电系统(VSC-HVDC)组成的新型双馈入直流输电系统(Double-InfeedHVDC)向无源网络输送电能。建立了利用VSC-HVDC启动HVDC的详细模型,并设计了Double-InfeedHVDC的控制系统。为了研究该双馈入直流输电系统的稳态和暂态性能,分别针对VSC-HVDC启动HVDC的特性和HVDC逆变侧发生三相短路故障时的特性进行了研究。PSCAD/EMTDC下的仿真结果表明,Double-InfeedHVDC系统可以为无源网络供电,同时具有良好的动态和故障恢复性能。

  10. Small Signal Model for VSC-HVDC Connected DFIG-Based Offshore Wind Farms

    Directory of Open Access Journals (Sweden)

    Kai Liao

    2014-01-01

    Full Text Available Large-scale offshore wind farms are integrated with onshore ac grids through the voltage source converter based high voltage direct current (VSC-HVDC transmission system. The impact on the stability of the ac grids will be significant. The small signal model of a wind farm connected with voltage source converter based dc transmission system is studied in this paper. A suitable model for small signal stability analysis is presented. The control system of wind generator and the HVDC system has also been modeled in this model for small signal stability analysis. The impact of the control parameters on the network stability is investigated.

  11. Power Delivery in Multiterminal VSC-HVDC Transmission System for Offshore Wind Power Applications

    DEFF Research Database (Denmark)

    Silva, Rodrigo Da; Teodorescu, Remus; Rodriguez, Pedro

    2010-01-01

    This paper deals with one of the challenges in the field of offshore wind power systems: power transmission among the wind farms and the land when there is more than one AC grid to be considered. This case is known in the literature as multiterminal connection. The proposed studies are going to p...

  12. An adaptive neuro fuzzy inference system controlled space cector pulse width modulation based HVDC light transmission system under AC fault conditions

    Science.gov (United States)

    Ajay Kumar, M.; Srikanth, N.

    2014-03-01

    In HVDC Light transmission systems, converter control is one of the major fields of present day research works. In this paper, fuzzy logic controller is utilized for controlling both the converters of the space vector pulse width modulation (SVPWM) based HVDC Light transmission systems. Due to its complexity in the rule base formation, an intelligent controller known as adaptive neuro fuzzy inference system (ANFIS) controller is also introduced in this paper. The proposed ANFIS controller changes the PI gains automatically for different operating conditions. A hybrid learning method which combines and exploits the best features of both the back propagation algorithm and least square estimation method is used to train the 5-layer ANFIS controller. The performance of the proposed ANFIS controller is compared and validated with the fuzzy logic controller and also with the fixed gain conventional PI controller. The simulations are carried out in the MATLAB/SIMULINK environment. The results reveal that the proposed ANFIS controller is reducing power fluctuations at both the converters. It also improves the dynamic performance of the test power system effectively when tested for various ac fault conditions.

  13. A Simulation Modeling Method of Equivalent Network to Simulate DC Magnetic Bias in Transformers Caused by Multi-Infeed HVDC Transmission Systems%模拟多馈入直流引起变压器直流偏磁的等值电网仿真建模方法

    Institute of Scientific and Technical Information of China (English)

    王薇薇; 刘翀; 朱艺颖; 蒋卫平

    2013-01-01

    There are four HVDC power transmission lines connected with Shanghai power grid, so the number of substations near to the inversion stations is unceasingly increased and it makes the DC magnetic bias phenomena in transformers frequently occurred. In allusion to the increasing of DC current in AC transformer neutrals caused by different operation modes of multi-infeed HVDC transmission system, a simulation model of equivalent network suited to such condition is built. The built equivalent model is divided into two parts, namely the above-ground part and the underground part, the above-ground part includes detailed models of four HVDC power transmission lines and the reasonable equivalence of the frame of Shanghai AC power grid, and the underground part is the series-parallel fitting of earth electrode resistances of HVDC transmission systems with the grounding grid resistance from the earth electrode to the transformer to be researched. The built model is validated by the measured current data of AC transformer neutrals during the monopole high power test of the second ±500 kV HVDC project from the Three Gorges to Shanghai and that during mono-polar ground return operation mode of ±800 kV DC transmission project from Xiangjiaba to Shanghai, and simulation results show that the proposed modeling method is effective and feasible. Using the built model, the impacts of multi-infeed HVDC transmission system under various operation modes on DC current flowing in AC transformer are researched, and the research results are available for reference to further research on the measures to suppress neutral DC current of transformers located at the region with receiving ends of multi-infeed HVDC transmission system.%上海地区有4回直流输电工程接入,逆变侧附近的变电站不断增多,变压器直流偏磁现象出现频繁。针对由多直流馈入而引起的交流变压器中性点直流电流增大的问题,建立了适用于这种情况的地区等值

  14. Grid Integration of Large PV Power Systems Using HVDC Link

    Directory of Open Access Journals (Sweden)

    Gamal Sowilam

    2016-09-01

    Full Text Available This paper explores the interconnection of large scale Photo-Voltaic (PV systems to the grid though a High Voltage Direct Current (HVDC link. HVDC link is recently utilized for transmission lines longer than 50 km. It is usually utilized to interconnect two asynchronous grids with the same or different frequencies while avoiding stability disturbances greatly. A suitable Maximum Power Point Tracking (MPPT techniques is employed to control the performance of the integrated PV system. The system of the HVDC link has two 12-pulse converter using thyristor-bridges. The delay and the extinction angles at the rectifier and the inverter units control the flow and the quantity of the transmitted power from the PV system into the grid. Fixed capacitors and filters are used to provide the AC side with the required reactive power and reduce the harmonic contents. For evaluation purposes, different simulation investigations are carried out with a detailed modeling using the MATLAB. These tests corroborate the efficacy of HVDC link for integrating large PV systems to electrical grids.

  15. HVDC Ground Electrodes - a Source of Geophysical Data

    Science.gov (United States)

    Freire, P. F.; Pereira, S. Y.

    2015-12-01

    The HVDC electrode is a component of a High Voltage Direct Current energy transmission system, and is designed to inject into the ground continuous currents up to 3500 A. The typical HVDC ground electrode is a ring of vertical conductors, 1 km wide, buried a few tens of meters.The design of a HVDC electrode is based on extensive geological, geotechnical and geophysical surveys. Geophysical data are usually electrical (VES) and electromagnetic (TEM/MT) acquisitions, for the modeling of the shallow, near-surface and deep layers of the crust. This survey aims, first, the electrode site selection, and then, at the selected site, this data is combined into a single apparent resistivity curve, which is inverted, allowing for the determination of the layered geoelectric crust model. The injection of electrical continuous current in the electrode is then simulated, with the geoelectric crust model, for the determination of the soil surface potential profile (which is usually asymmetric for different directions, due to non-1D geoelectric models).For the commissioning of a HVDC electrode, field measurements are done, such as electrode grounding resistance, soil surface potentials and metal-to-soil potentials at specific structures (buried pipelines, for instance).The geophysical data acquired during the design phase is a set of data completely independent from the electrical data acquired during the electrode commissioning phase, and both are correlated by the geoelectric model. It happens, therefore, that the geoelectric model can be calibrated based on the electrical data, with the correction of static shifts and other adjustments.This paper suggests that the commissioning of HVDC systems should be associated to a research & development program, with a university or foundation. The idea is to enjoy the opportunity of a more complete field survey, with the acquisition of a wide set of data for a better geological characterization of the area where the electrode was built.

  16. Modeling HVDC links in composite reliability evaluation: issues and solutions

    Energy Technology Data Exchange (ETDEWEB)

    Reis, Lineu B. de [Sao Paulo Univ., SP (Brazil). Escola Politecnica; Ramos, Dorel S. [Centrais Eletricas de Sao Paulo, SP (Brazil); Morozowski Filho, Marciano [Santa Catarina Univ., Florianopolis, SC (Brazil)

    1992-12-31

    This paper deals with theoretical and practical aspects of HVDC link modeling for composite (generation and transmission) system reliability evaluation purposes. The conceptual framework used in the analysis, as well as the practical aspects, are illustrated through an application example. Initially, two distinct HVDC link operation models are described: synchronous and asynchronous. An analysis of the most significant internal failure modes and their effects on HVDC link transmission capability is presented and a reliability model is proposed. Finally, a historical performance data of the Itaipu HVDC system is shown. 6 refs., 5 figs., 8 tabs.

  17. Electrical Structure of Future Off-shore Wind Power Plant with a High Voltage Direct Current Power Transmission

    DEFF Research Database (Denmark)

    Sharma, Ranjan

    to control and as such a high current capacity of the WPP side VSC might be required. Detailed simulation results are included in the report. The other option is to use a DC chopper, the results of which are also presented in detail in the report. It is observed that a DC chopper can provide a simple...... are related to surplus reactive power and added losses. On the other hand, HVDC transmission system can be arbitrarily long and for long distance power transmission requirement it provides much better efficiency compared to a corresponding HVAC system. HVDC may provide a viable solution for high power...... to trip off during temporary grid side faults, commonly described as low voltage fault-ride-through requirement. There are four different fault-ride-through options discussed in the report. The first option includes controlling of collector network frequency. This provides a very good opportunity to use...

  18. Modelling and Simulation of SVPWM Based Vector Controlled HVDC Light Systems

    Directory of Open Access Journals (Sweden)

    Ajay Kumar MOODADLA

    2012-11-01

    Full Text Available Recent upgrades in power electronics technology have lead to the improvements of insulated gate bipolar transistor (IGBT based Voltage source converter High voltage direct current (VSC HVDC transmission systems. These are also commercially known as HVDC Light systems, which are popular in renewable, micro grid, and electric power systems. Out of different pulse width modulation (PWM schemes, Space vector PWM (SVPWM control scheme finds growing importance in power system applications because of its better dc bus utilization. In this paper, modelling of the converter is described, and SVPWM scheme is utilized to control the HVDC Light system in order to achieve better DC bus utilization, harmonic reduction, and for reduced power fluctuations. The simulations are carried out in the MATLAB/SIMULINK environment and the results are provided for steady state and dynamic conditions. Finally, the performance of SVPWM based vector controlled HVDC Light transmission system is compared with sinusoidal pulse width modulation (SPWM based HVDC Light system in terms of output voltage and total harmonic distortion (THD.

  19. Digital controller for hybrid filter in HVDC based on approximate inverse system

    Institute of Scientific and Technical Information of China (English)

    SU Ling; ZHAO Dong-yuan; CHEN Jian-ye; WANG Zan-ji

    2006-01-01

    In order to eliminate the characteristic harmonics in high voltage direct current (HVDC) transmission systems and to simplify the analog controller structure,this paper proposes a new digital controller by adopting an approximate inverse system control strategy according to the frequency response characteristic of the hybrid power filter.The proposed digital controller is implemented with a TMS320C32 DSP,including a series of parallel digital band-pass filters,phase shifters and amplifiers.The results of both simulations based on PSCAD and experiments on a 30 kVA HVDC system prove that the proposed digital control system is stable and efficient for eliminating the harmonics.

  20. Site Selection for Hvdc Ground Electrodes

    Science.gov (United States)

    Freire, P. F.; Pereira, S. Y.

    2014-12-01

    High-Voltage Direct Current (HVDC) transmission systems are composed of a bipole transmission line with a converter substation at each end. Each substation may be equipped with a HVDC ground electrode, which is a wide area (up to 1 km Ø) and deep (from 3 to 100m) electrical grounding. When in normal operation, the ground electrode will dissipate in the soil the unbalance of the bipole (~1.5% of the rated current). When in monopolar operation with ground return, the HVDC electrode will inject in the soil the nominal pole continuous current, of about 2000 to 3000 Amperes, continuously for a period up to a few hours. HVDC ground electrodes site selection is a work based on extensive geophysical and geological surveys, in order to attend the desired design requirements established for the electrodes, considering both its operational conditions (maximum soil temperature, working life, local soil voltage gradients etc.) and the interference effects on the installations located up to 50 km away. This poster presents the geophysical investigations conducted primarily for the electrodes site selection, and subsequently for the development of the crust resistivity model, which will be used for the interference studies. A preliminary site selection is conducted, based on general geographical and geological criteria. Subsequently, the geology of each chosen area is surveyed in detail, by means of electromagnetic/electrical geophysical techniques, such as magnetotelluric (deep), TDEM (near-surface) and electroresistivity (shallow). Other complementary geologic and geotechnical surveys are conducted, such as wells drilling (for geotechnical characterization, measurement of the water table depth and water flow, and electromagnetic profiling), and soil and water sampling (for measurement of thermal parameters and evaluation of electrosmosis risk). The site evaluation is a dynamic process along the surveys, and some sites will be discarded. For the two or three final sites, the

  1. Simulation of offshore wind farm integrated into power grid using VSC HVDC system

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Hui; Nguyen, Mau Cuong; Rudion, Krzystof; Styczynski, Zbigniew Antoni [Magdeburg Univ. (Germany). Chair for Electric Power Networks and Renewable Energy Sources

    2011-07-01

    In this paper, the integration of an offshore wind farm into a power grid is studied based on the simulation of a developed test system including an aggregated DFIG wind farm model and VSC HVDC transmission system model. This paper concentrates on the transient stability and system performance with an applied controller for DFIG and HVDC converter stations. The results are obtained by simulation of the test system subjected to severe grid disturbance, e.g. three-phase short circuit fault at the point of common coupling (PCC). Furthermore, the conformity of the system performance with the current grid code, e.g. fault-ride through capability is investigated and confirmed from the simulation results. In addition, a DC-chopper circuit is modeled to protect the HVDC-link from the overvoltage without disconnection during grid faults. Different time delays of the DC-chopper are considered and simulated to investigate its influence on the system dynamics and performance. (orig.)

  2. One-Terminal Fault Location for VSC-HVDC Transmission Lines Based on Principles of Parameter Identification%基于参数识别原理的VSC-HVDC输电线路单端故障定位

    Institute of Scientific and Technical Information of China (English)

    宋国兵; 李德坤; 褚旭; 饶菁; 蔡新雷

    2012-01-01

    为保障电压源换流器型直流输电(voltage source converter HVDC,VSC-HVDC)系统的可靠运行,提出一种基于参数识别原理的VSC-HVDC输电线路单端故障定位方法.由于VSC-HVDC输电线路两端并联大电容,识别故障距离的时候,在0模分量网络中可以把两端的换流站系统等效为电容,通过参数识别的原理列写出包含故障距离和过渡电阻2个未知参数的故障定位时域微分方程,通过最小二乘法优化求解该方程即可得到故障距离和过渡电阻,从而实现故障定位.PSCAD下的仿真结果表明,该方法能够实现VSC-HVDC输电线路的准确故障定位,最大测距误差不超过1%.该方法仅需要单端电气量就能实现准确故障定位,对采样频率的要求不高,理论上不受过渡电阻的影响,可以满足VSC-HVDC输电线路故障测距的要求.%To ensure reliable operation of voltage source converter HVDC (VSC-HVDC) transmission system, a one-terminal fault location method for VSC-HVDC transmission line is proposed. Because high-capacity capacitors are connected to both ends of VSC-HVDC transmission line, so during the fault location the converter station systems at both ends of VSC-HVDC transmission line can be equivalent to capacitors in the network of zero-mode component, and by means of the principle of parameter identification the differential equations in time-domain, which contains two unknown parameters of fault distance and transition resistance, can be listed, and solving this equation by least square optimization both fault distance and transition resistance can be attained, thus the fault location is implemented. The proposed method only needs single end electric quantities and is undemanding to sampling frequency, besides, theoretically this method is not affected by transition resistance, so it can meet the demand on fault location for VSC-HVDC transmission lines. Results of PSCAD simulation show that the proposed method can implement

  3. 多换流器并联运行的直流输电工程暂态过电压%Transient Overvoltage of HVDC Power Transmission Project With ParaUelly Operated Converters

    Institute of Scientific and Technical Information of China (English)

    张赟; 舒畅; 殷威扬; 刘宝宏; 聂定珍

    2012-01-01

    随着直流输电特别是多端直流输电技术的发展及广泛应用,多个换流器并联连接的接线方案得到越来越多的研究和应用。依托±400kV青海一西藏直流联网工程采用电磁暂态仿真的方法研究了2换流器并联结构与单换流器结构相比,在各种故障工况下系统过电压水平,以及阀避雷器、交流避雷器、中性母线避雷器、直流极线和6脉动中点避雷器电流、能量变化的规律。结果表明,在某些工况下,故障后过电压水平和避雷器电流、能量均有变化。发生换流变阀侧接地故障时,阀避雷器能量增加2倍以上,交流单相、三相接地故障后,交流避雷器能量增加60%,因此在绝缘配合设计时需要相应增加避雷器并联数量。所得研究结论可为多换流器并联结构过电压与绝缘配合设计提供参考。%Along with the development and widespread application of HVDC power transmission technology, especially the multi-terminal HVDC power transmission, special attentions are paid to the research on the wiring scheme of parallelly connected multi-converters and such connection scheme is widely applied. Based on 4-400 kV DC power transmission project from Qinghai to Tibet in which the structure of two converters are parallelly connected, the apporach of electromagnetic transient simulation is adopted to research overvotlage level of this system under various fault conditions and the variation law of current and energy in valve arresters, AC arresters, neutral bus arrester, DC pole arresters and 6-pulse neutral bus arrester, and the simulation results are compared with those of single converter structure. Simulation results show that under some operating conditions the post-fault overvoltage level and current and energy in arresters vary. When gounding fault occurs at the valve side of converters, the energy in valve arrester will be increased to more than triple, and when single-phase or

  4. Control of transformerless MMC-HVDC during asymmetric grid faults

    DEFF Research Database (Denmark)

    Timofejevs, Artjoms; Gamboa, Daniel; Liserre, Marco;

    2013-01-01

    Modular multilevel converter (MMC) is the latest converter topology suitable for the transformerless applications in HVDC transmission. HVDC systems are required to remain connected during grid faults, provide grid support and completely decouple the healthy side from the faulty one. The MMC...

  5. 新型混合高压直流输电技术在海上风电场并网中的应用%Hybrid HVDC Transmission Topology for Offshore Wind Farm Integration

    Institute of Scientific and Technical Information of China (English)

    尹瑞; 江道灼; 胡鹏飞; 谷泓杰; 黄帅

    2015-01-01

    对由双馈风电机组组成的海上风电场采用混合高压直流输电技术并网时风电场内部的电压和频率控制进行了研究。混合高压直流输电系统由双桥十二脉波不控整流换流器(DBC)、模块化多电平换流器和高压直流输电线路组成。首先,通过深入的理论分析阐明当由双馈风电机组组成的海上风电场采用混合高压直流输电技术并网时,风电场内部的电压可以自动维持在一个合适的范围内并随双馈风电机组输出有功功率的变化而变化。在此基础上,设计了双馈风电机组转子侧换流器的控制器以实现对风电场内部交流系统频率的控制,同时实现了双馈风电机组输出有功功率的最大功率点跟踪。为防止岸上公共连接点发生三相接地短路故障时基于 DBC 的高压直流输电系统发生过电压,设计了故障时双馈风电机组的控制策略。最后,对建立的采用混合高压直流输电技术并网的海上风电场模型进行了数字仿真,仿真结果验证了理论分析的正确性和所提出控制策略的有效性。%A novel control strategy is designed for the offshore doubly fed induction generator (DFIG) based wind farm connected to the onshore system through a hybrid high voltage direct current (HVDC) transmission topology.The hybrid HVDC is composed of a modular multilevel converter and a diode rectifier.Detailed analysis is made to prove that the offshore AC-grid voltage can be maintained in a proper range during normal operation.Based on this precondition,a control strategy for the offshore AC-grid frequency and maximum power point tracking (MPPT)of the DFIG is proposed.In order to ensure that the voltage of the HVDC link is lower than its upper limit during the onshore point of common coupling (PCC) short-circuit, the fault ride-through control of the DFIG is also designed.Finally,a digital simulation system of the offshore DFIG-based wind farm and

  6. Application of Flexible HVDC Transmission Technology in Grid-connected Wind Power%柔性直流输电技术在风电并网中的应用

    Institute of Scientific and Technical Information of China (English)

    朱奕帆

    2011-01-01

    简述国内常规风电的并网方式,并以上海南汇风电场柔性直流输电示范工程为例阐述应用柔性直流输电技术的新型风电并网方式。对比分析两种并网方式,提出柔性直流输电技术在风电并网上的优点。%The paper makes a review of the conventional grid connection modes for wind power in China.Shanghai Nanhui Wind Power Farm,the flexible HVDC transmission demonstration project,exemplifies the new grid connection pattern.Comparatively,the flexible HVDC transmission technology exhibits great superiorities in wind power connection to grid.

  7. Operating characteristic analysis of a 400 mH class HTS DC reactor in connection with a laboratory scale LCC type HVDC system

    Science.gov (United States)

    Kim, Sung-Kyu; Kim, Kwangmin; Park, Minwon; Yu, In-Keun; Lee, Sangjin

    2015-11-01

    High temperature superconducting (HTS) devices are being developed due to their advantages. Most line commutated converter based high voltage direct current (HVDC) transmission systems for long-distance transmission require large inductance of DC reactor; however, generally, copper-based reactors cause a lot of electrical losses during the system operation. This is driving researchers to develop a new type of DC reactor using HTS wire. The authors have developed a 400 mH class HTS DC reactor and a laboratory scale test-bed for line-commutated converter type HVDC system and applied the HTS DC reactor to the HVDC system to investigate their operating characteristics. The 400 mH class HTS DC reactor is designed using a toroid type magnet. The HVDC system is designed in the form of a mono-pole system with thyristor-based 12-pulse power converters. In this paper, the investigation results of the HTS DC reactor in connection with the HVDC system are described. The operating characteristics of the HTS DC reactor are analyzed under various operating conditions of the system. Through the results, applicability of an HTS DC reactor in an HVDC system is discussed in detail.

  8. 环网型混合五端直流输电系统的建模与仿真%Modeling and Simulation of Hybrid Five-terminal HVDC Transmission System

    Institute of Scientific and Technical Information of China (English)

    赵越; 周飞; 宗波; 许建中; 赵成勇; 袁艺嘉; 郭裕群

    2015-01-01

    随着直流输电技术发展日益成熟,大规模可再生能源的并网和多落点受电的研究正在成为直流输电行业的研究热点。利用PSCAD建立混合五端直流输电仿真模型,该模型可将我国西北部地区丰富的可再生能源通过架空线远距离输送给中东部负荷密集区,并根据沿海岛屿的具体情况,实现海上风电场的并网或者孤岛供电。模型中用四端互联形成环网结构,且在两电平 VSC 站和 HB-MMC 站直流母线出口处加装大功率二极管阀组,用以限制直流系统故障下故障电流的穿越;然后,对系统直流侧接地故障后的运行特性进行仿真分析。仿真结果表明,所搭建的混合五端环网直流输电系统在稳态下能够安全稳定运行,在直流线路接地故障时能够隔离故障电流。%With the DC transmission technology becoming more mature, the problems of how to connect renewable energy resources to power grid and how to supply enough power to the users in different regions are becoming the hotspots in the research of HVDC. A simulation model of a hybrid five-terminal HVDC transmission system is designed by using PSCAD, which can be used for transmitting the rich renewable energy in northwest to cent ral and eastern China that are in urgent need of electricity power using overhead lines over long distance. The design also takes the demand of the offshore islands into account, and can achieve offshore wind power integration or power supply to the islands. In the model, there are four terminals interconnected into ring network architecture, and high power diode valves are installed at the exit of the DC bus in the two-level VSC station and HB-MMC station, which is used to cut off the fault current when DC system fault occurs. What’s more, the article analyzes the operating characteristics of the system when ground fault on the DC side occurs through simulation. Simulation results show that the

  9. Hybrid HVDC circuit breaker with self-powered gate drives

    OpenAIRE

    Effah, Francis Boafo; Watson, Alan James; Ji, Chao; Amankwah, Emmanuel K.; Johnson, Christopher Mark; Davidson, Colin; Clare, Jon C.

    2016-01-01

    The ever increasing electric power demand and the advent of renewable energy sources have revived the interest in high-voltage direct current (HVDC) multi-terminal networks. However, the absence of a suitable circuit breaker or fault tolerant VSC station topologies with the required characteristics (such as operating speed) have, until recently, been an obstacle in the development of large scale multi-terminal networks for HVDC. This paper presents a hybrid HVDC circuit breaker concept which...

  10. Hybrid HVDC circuit breaker with self-powered gate drives

    OpenAIRE

    Effah, Francis Boafo; Watson, Alan James; Ji, Chao; Amankwah, Emmanuel K.; Johnson, Christopher Mark; Davidson, Colin; Clare, Jon C.

    2016-01-01

    The ever increasing electric power demand and the advent of renewable energy sources have revived the interest in high-voltage direct current (HVDC) multi-terminal networks. However, the absence of a suitable circuit breaker or fault tolerant VSC station topologies with the required characteristics (such as operating speed) have, until recently, been an obstacle in the development of large scale multi-terminal networks for HVDC. This paper presents a hybrid HVDC circuit breaker concept which ...

  11. Hard- and software of real time simulation tools of Electric Power System for adequate modeling power semiconductors in voltage source convertor based HVDC and FACTS

    Directory of Open Access Journals (Sweden)

    Ufa Ruslan A.

    2014-01-01

    Full Text Available The motivation of the presented research is based on the needs for development of new methods and tools for adequate simulation of Flexible Alternating Current Transmission System (FACTS devices and High Voltage Direct Current Transmission (HVDC system as part of real electric power systems (EPS. For that, a hybrid approach for advanced simulation of the FACTS and HVDC based on Voltage Source is proposed. The presented simulation results of the developed hybrid model of VSC confirm the achievement of the desired properties of the model and the effectiveness of the proposed solutions.

  12. Frequency Regulation Strategies in Grid Integrated Offshore Wind Turbines via VSC-HVDC Technology: A Review

    Directory of Open Access Journals (Sweden)

    Jafar Jallad

    2017-08-01

    Full Text Available The inclusion of wind energy in a power system network is currently seeing a significant increase. However, this inclusion has resulted in degradation of the inertia response, which in turn seriously affects the stability of the power system’s frequency. This problem can be solved by using an active power reserve to stabilize the frequency within an allowable limit in the event of a sudden load increment or the loss of generators. Active power reserves can be utilized via three approaches: (1 de-loading method (pitching or over-speeding by a variable speed wind turbine (VSWT; (2 stored energy in the capacitors of voltage source converter-high voltage direct current (VSC-HVDC transmission; and (3 coordination of frequency regulation between the offshore wind farms and the VSC-HVDC transmission. This paper reviews the solutions that can be used to overcome problems related to the frequency stability of grid- integrated offshore wind turbines. It also details the permanent magnet synchronous generator (PMSG with full-scale back to back (B2B converters, its corresponding control strategies, and a typical VSC-HVDC system with an associated control system. The control methods, both on the levels of a wind turbine and the VSC-HVDC system that participate in a system’s primary frequency control and emulation inertia, are discussed.

  13. Characteristics and Application of VSC-HVDC Transmission System%VSC-HVDC输电系统的特点与应用

    Institute of Scientific and Technical Information of China (English)

    唐博; 王鹏

    2014-01-01

    轻型直流输电系统是基于VSC技术的新型直流输电技术。介绍轻型直流输电基本原理,对比轻型直流输电技术与传统直流输电技术在结构和功能方面的区别,阐述轻型直流输电的优点,并对其应用进行总结和展望,以期为轻型直流输电技术在我国的应用和发展提供一定参考。%With the development of semiconductors and renewable generation, a new HVDC technology-HVDC Light based on VSC (Voltage Sourced Converters) arises. The principle of HVDC Light technology is presented in this paper and then a comparison of config-uration as well as function is made between HVDC Light and conventional HVDC, and the merits of HVDC Light are clarified. At last, the application of HVDC Light is summarized and prospected.

  14. Method and system for a gas tube-based current source high voltage direct current transmission system

    Energy Technology Data Exchange (ETDEWEB)

    She, Xu; Chokhawala, Rahul Shantilal; Bray, James William; Sommerer, Timothy John; Zhou, Rui; Zhang, Di

    2017-08-29

    A high-voltage direct-current (HVDC) transmission system includes an alternating current (AC) electrical source and a power converter channel that includes an AC-DC converter electrically coupled to the electrical source and a DC-AC inverter electrically coupled to the AC-DC converter. The AC-DC converter and the DC-AC inverter each include a plurality of legs that includes at least one switching device. The power converter channel further includes a commutating circuit communicatively coupled to one or more switching devices. The commutating circuit is configured to "switch on" one of the switching devices during a first portion of a cycle of the H-bridge switching circuits and "switch off" the switching device during a second portion of the cycle of the first and second H-bridge switching circuits.

  15. Controller Architecture Design for MMC-HVDC

    Directory of Open Access Journals (Sweden)

    ZHANG, B.

    2014-05-01

    Full Text Available Compared with high voltage direct current (HVDC, the primary and secondary systems of modular multilevel converter based HVDC (MMC-HVDC are complicated. And the characteristics of the control system determine the properties of the MMC-HVDC system to a certain extent. This paper investigates the design of control architecture. First, the structure and parameters of the 21-level MMC-HVDC are designed. Second, the framework of the control system is studied in details and a complete control system is established. The communication mode and content are built between each layer, and the control system program is developed and debugged. Then The steady state test platform of the sub-module and the relevant control system are designed. Finally, the steady-state tests and the system test of the physical MMC-HVDC simulation system are conducted, which prove that the SMC can control the sub-module (SM efficiently, and the control system could realize efficient start and stop of the physical system. Meanwhile, the capacitor voltage balance between the sub-modules and the basic fault protection and control of the DC voltage and power are verified to be effective.

  16. Enhanced Dynamic Voltage Stability Support by VSC-HVDC for Offshore Wind Applications using Trajectory Sensitivity Analysis

    DEFF Research Database (Denmark)

    Liu, Hongzhi; Chen, Zhe; Liu, Leo

    2013-01-01

    . In this paper, VSC-HVDC transmission system is used to integrate a large-scale wind power plant into the onshore power grid. For different voltage support strategies of VSC-HVDC, a trajectory sensitivity analysisbased approach is proposed to find the minimum onshore VSC capacity with which the VSC-HVDC can...

  17. Grid connection of large offshore wind farms using HVDC

    Science.gov (United States)

    Xu, Lie; Andersen, Bjarne R.

    2006-07-01

    This article describes the use of high-voltage DC (HVDC) transmission systems for connection of large offshore wind farms using doubly fed induction generators (DFIGs) to the main grid. HVDC systems based on voltage source converters (VSC transmission) and on line-commutated converters (LCC HVDC) are discussed. The article describes proposed system configurations, operating principles and controls for the two technologies. PSCAD/EMTDC simulations are presented to demonstrate the robust performance of the proposed systems during variation of generation and onshore AC fault conditions. Copyright

  18. New Progress on Self-Reliant Innovation of HVDC Technology

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    It is an important direction for China's power industry to master the design and the equipment manufacturing core technology of large-capacity HVDC power transmission systems,and to form the sustainable development capability.

  19. Research Status of HVDC XLPE Cable%高压直流XLPE电缆研究现状

    Institute of Scientific and Technical Information of China (English)

    王亚; 吕泽鹏; 吴锴; 王霞; 刘通; 李锐海

    2014-01-01

    The international application of high voltage direct current(HVDC) transmission cable was pre-sented. The research situation of space charge and test methods of the HVDC cable was summarized, and the development direction of the HVDC cable materials and test methods were prospected.%介绍了国际高压直流输电电缆绝缘的应用情况,概述了高压直流电缆的空间电荷与直流电缆测试方法的研究情况,展望了高压直流电缆材料及测试技术的发展方向。

  20. New Breed of Bipolar MMC-HVDC Topology for Overhead Line Transmission%适用于架空线路输电的新型双极MMC-HVDC拓扑

    Institute of Scientific and Technical Information of China (English)

    薛英林; 徐政

    2013-01-01

    在充分借鉴传统直流输电工程结线方式的基础上,提出了一种适用于架空线路输电的新型双极模块化多电平换流器型高压直流输电(MMC-HVDC)系统拓扑.该拓扑中换流器采用基于箝位双子模块的改进型模块化多电平换流器(MMC),接地极线从上下2个换流器串联构成的双极结构中间引出.重点分析了换流器在故障条件下的等值电路和直流闭锁机理,并设计了直流侧故障后的详细控制策略,并用PSCAD/EMTDC仿真软件验证了该系统拓扑的有效性和可行性.结果表明:双极拓扑具有运行方式灵活、系统可靠性高等优点;由于二极管反向阻断和箝位作用,换流器在封锁所有绝缘栅双极型晶体管(IGBT)触发脉冲后数ms内就能实现直流闭锁,因此无需交流断路器动作,仅依靠换流器自身动作就能抑制短路电流;所设计的控制时序可有效处理直流侧的故障,并在暂时性故障下帮助系统迅速重启动,减少系统停运时间.%We propose a new type of bipolar MMC-HVDC topology for overhead line transmission by referencing the traditional HVDC system topology. This topology adopts improved modular multilevel converters (MMC) based on clamp double sub-modules. The ground electrode is led from the junction center of the bipolar structure, which consists of up-and-down converters in series. Furthermore, the equivalent circuit during DC fault and the fault blocking mechanism are analyzed, a control strategy and action sequence of the converter under the DC fault is proposed, and the feasibility and validity of the bipolar system are verified by PSCAD/EMTDC simulations. Several results are obtained from the simulation; the bipolar topology offers many features such as flexible operation modes and high system reliability, etc. ; Owing to reverse blocking and voltage clamping of diodes, the DC blocking capability is achieved within a few milliseconds after turning off all insulated gate

  1. Modeling and Simulation Analysis on HVDC Snubber%高压直流缓冲器的建模分析及应用

    Institute of Scientific and Technical Information of China (English)

    屈鲁; 李格

    2016-01-01

    HVDC snubber is a transformer-like short-circuit current suppression device. It can suppress and interrupt short-circuit current of HVDC transmission effectively combined with HVDC circuit-breaker. In this paper, HVDC snubber model is developed by adopting nonlinear resistance and nonlinear inductance in parallel based on its nonlinear equivalent circuit. Then experiment and simulation are conducted to verify HVDC snubber performance, and results show that HVDC snubber can effectively suppress short-circuit current and reduce arcing time. Dynamic response of its non-linear equivalent circuit is also analyzed, and results show that HVDC snubber can suppress short circuit current effectively only in over-damping state. Finally, a hybrid HVDC short-circuit protection scheme is proposed, combining HVDC snubber and HVDC circuit-breaker, and its feasibility is analyzed.%高压直流缓冲器是一种类变压器的直流短路电流抑制装置,结合高压直流断路器可有效地抑制、切断直流输电系统中的短路电流。首先基于高压直流缓冲器的等效电路,采用非线性电阻和非线性电感并联的方法建立其等效模型;接着对高压直流缓冲器的工作性能进行了实验验证和仿真验证,结果表明高压直流缓冲器能够有效地抑制短路电流的峰值和燃弧时间;然后对高压直流缓冲器的非线性等效电路进行动态响应分析,分析结果表明高压直流缓冲器只有工作于过阻尼状态才能有效地抑制短路电流;最后结合高压直流缓冲器和高压直流断路器,提出一种混合式高压直流短路保护方案,并对其可行性进行了分析。

  2. Transient analysis of an HTS DC power cable with an HVDC system

    Science.gov (United States)

    Dinh, Minh-Chau; Ju, Chang-Hyeon; Kim, Jin-Geun; Park, Minwon; Yu, In-Keun; Yang, Byeongmo

    2013-11-01

    The operational characteristics of a superconducting DC power cable connected to a highvoltage direct current (HVDC) system are mainly concerned with the HVDC control and protection system. To confirm how the cable operates with the HVDC system, verifications using simulation tools are needed. This paper presents a transient analysis of a high temperature superconducting (HTS) DC power cable in connection with an HVDC system. The study was conducted via the simulation of the HVDC system and a developed model of the HTS DC power cable using a real time digital simulator (RTDS). The simulation was performed with some cases of short circuits that may have caused system damage. The simulation results show that during the faults, the quench did not happen with the HTS DC power cable because the HVDC controller reduced some degree of the fault current. These results could provide useful data for the protection design of a practical HVDC and HTS DC power cable system.

  3. An Examination of AC/HVDC Power Circuits for Interconnecting Bulk Wind Generation with the Electric Grid

    Directory of Open Access Journals (Sweden)

    Daniel Ludois

    2010-06-01

    Full Text Available The application of high voltage dc (HVDC transmission for integrating large scale and/or off-shore wind generation systems with the electric grid is attractive in comparison to extra high voltage (EHV ac transmission due to a variety of reasons. While the technology of classical current sourced converters (CSC using thyristors is well established for realization of large HVDC systems, the technology of voltage sourced converters (VSC is emerging to be an alternative approach, particularly suitable for multi-terminal interconnections. More recently, a more modular scheme that may be termed ‘bridge of bridge’ converters (BoBC has been introduced to realize HVDC systems. While all these three approaches are functionally capable of realizing HVDC systems, the converter power circuit design trade-offs between these alternatives are not readily apparent. This paper presents an examination of these topologies from the point of view of power semiconductor requirements, reactive component requirements, operating losses, fault tolerance, multi-terminal operation, modularity, complexity, etc. Detailed analytical models will be used along with a benchmark application to develop a comparative evaluation of the alternatives that maybe used by wind energy/bulk transmission developers for performing engineering trade-off studies.

  4. An examination of AC/HVDC power circuits for interconnecting bulk wind generation with the electric grid

    Energy Technology Data Exchange (ETDEWEB)

    Ludois, D.; Venkataramanan, G. [Department of Electrical and Computer Engineering, University of Wisconsin-Madison 1415 Engineering Dr. Madison WI 53706 (United States)

    2010-06-15

    The application of high voltage DC (HVDC) transmission for integrating large scale and/or off-shore wind generation systems with the electric grid is attractive in comparison to extra high voltage (EHV) AC transmission due to a variety of reasons. While the technology of classical current sourced converters (CSC) using thyristors is well established for realization of large HVDC systems, the technology of voltage sourced converters (VSC) is emerging to be an alternative approach, particularly suitable for multi-terminal interconnections. More recently, a more modular scheme that may be termed 'bridge of bridge' converters (BoBC) has been introduced to realize HVDC systems. While all these three approaches are functionally capable of realizing HVDC systems, the converter power circuit design trade-offs between these alternatives are not readily apparent. This paper presents an examination of these topologies from the point of view of power semiconductor requirements, reactive component requirements, operating losses, fault tolerance, multi-terminal operation, modularity, complexity, etc. Detailed analytical models will be used along with a benchmark application to develop a comparative evaluation of the alternatives that may be used by wind energy/bulk transmission developers for performing engineering trade-off studies. (author)

  5. 系统频率变化对直流系统触发控制环节的影响%Impact of Power Grid Frequency Deviation on Trigger Control of Converters in HVDC Power Transmission System

    Institute of Scientific and Technical Information of China (English)

    谭海燕; 徐敬友; 孙海顺

    2014-01-01

    系统的大功率缺额易引起较大的频率偏移。频率偏移过大可能导致直流系统(high voltage DC transmissionHVDC)触发脉冲异常,进而引发运行问题。以实际系统MACH2(modular advanced control hardware 2)为例,分析了触发控制原理及锁相环工作原理,重点研究了系统频率变化对锁相环工作及换相电压过零点判断的影响。在PSCAD/EMTDC仿真平台中搭建了MACH2触发环节的简化模型,仿真结果表明,频率变化会影响系统触发脉冲的产生,导致实际触发延迟角无法及时跟踪指令值,但对系统运行的影响不大。由于控制系统触发延迟角幅值限制环节的影响,系统频率升高及降低两种情况对直流系统的影响程度也有差别。%Severe power outage is easy to cause obvious grid frequency deviation, and too large frequency deviation may lead to abnormal triggering pulse in HVDC power transmission system and further causes the troubles in the operation of HVDC transmission system. Taking an actual system MACH2 (modular advanced control hardware 2) as example, the principle of trigger control and the working principle of phase-locked loop are analyzed, and the impacts of power grid frequency deviation on the working of phase-locked loop and the judgment of zero crossover points of the commutation voltage are emphatically researched. In PSCAD/EMTDC simulation platform a simplified model of the triggering link of MACH2 is constructed, and simulation results show that power grid frequency deviation affects the generation of system triggering pulses and makes the actual firing delay angle not be able to track the value of the reference in time, however is slightly affects the system operation. Due to amplitude limiter of firing delay angle in the control system, the impact of grid frequency increase on HVDC transmission system differs from the impact of grid frequency decrease.

  6. VSC-HVDC输电系统特点与应用%Characteristics and application of VSC-HVDC power transmission system

    Institute of Scientific and Technical Information of China (English)

    孟垂懿; 鲍洁秋; 武录

    2012-01-01

    随着半导体技术和新能源发电的发展,出现了基于VSC(Voltage Sourced Converters)技术的新型直流输电系统——轻型直流输电(HVDC Light),在介绍HvDC Light基本原理基础上,从结构和功能上与传统直流输电技术进行对比,阐述了HVDC Light的优点,并对其应用作了总结和展望.

  7. Behavior of highly diluted electrolytes in strong electric fields-prevention of alumina deposition on grading electrodes in HVDC transmission modules by CO2-induced pH-control.

    Science.gov (United States)

    Weber, Immo; Mallick, Bert; Schild, Matthias; Kareth, Sabine; Puchta, Ralph; van Eldik, Rudi

    2014-09-15

    Alumina deposition on platinum grading electrodes in high voltage direct current (HVDC) transmission modules is an unsolved problem that has been around for more than three decades. This is due to the unavoidable corrosion of aluminum heat sinks that causes severe damage to electrical power plants and losses in the range of a million Euro range per day in power outage. Simple experiments in a representative HV test setup showed that aluminates at concentrations even below 10(-8) mol L(-1) can deposit on anodes through neutralization by protons produced in de-ionized water (κ≤0.15 μS cm(-1)) at 20-35 kV (8 mA) per electrode. In this otherwise electrolyte-poor aqueous environment, the depositions are formed three orders of magnitude below the critical precipitation concentration at pH 7! In the presence of an inert electrolyte such as TMAT (tetramethylammonium-p-toluenesulfonate), at a concentration level just above that of the total dissolved aluminum, no deposition was observed. Deposition can be also prevented by doping with CO2 gas at a concentration level that is magnitudes lower than that of the dissolved aluminum. From an overview of aqueous aluminum chemistry, the mystery of the alumina deposition process and its inhibition by CO2 is experimentally resolved and fully explained by field accumulation and repulsion models in synergism with acid-base equilibria. The extraordinary size of the alumina depositions is accounted for in terms of proton tunneling through "hydrated" alumina, which is supported by quantum chemical calculations. As a consequence, pulse-purging with pure CO2 gas is presented as a technical solution to prevent the deposition of alumina.

  8. A comparison of the technological, economic, public policy, and environmental factors of HVDC and HVAC interregional transmission

    Directory of Open Access Journals (Sweden)

    Armando L. Figueroa-Acevedo

    2015-02-01

    Full Text Available The design of an interregional high-voltage transmission system in the US is a revolutionary technological concept that will likely play a significant role in the planning and operation of future electric power systems. Historically, the primary justification for building interregional high-voltage transmission lines in the US and around the world has been based on economic and reliability criteria. Today, the implementation renewable portfolio standards, carbon emission regulations, the improvements in the performance of power electronic systems, and unused benefits associated with capacity exchange during times of non-coincident peak demand, are driving the idea of designing an interregional high-voltage transmission system in the US. However, there exist challenges related to technical, economic, public policy, and environmental factors that hinder the implementation of such a complex infrastructure. The natural skepticism from many sectors of the society, in regards to how will the system be operated, how much will it cost, and the environmental impact that it could potentially create are among the most significant challenges to its rapid implementation. This publication aims at illustrating the technological, environmental, economic, and policy challenges that interregional HV transmission systems face today in the US, looking specifically at the Clean Line Rock Island project in Iowa.

  9. HVDC交流滤波器合闸的涌流研究%Simulation of Inrush Current at HVDC AC Filter Switching on

    Institute of Scientific and Technical Information of China (English)

    丛宝丰; 夏成军; 席亮

    2013-01-01

    HVDC系统交流滤波器的投入会产生较大涌流,会造成滤波器损坏,保护误动作,威胁系统安全.针对上述问题,采用了基于蒙特卡洛算法与自定义建模的仿真研究,对逆变侧滤波器涌流与表征三相电流不平衡性的零序电流进行了详细的计算,基于计算结果,提出加装POW装置与临时闭锁不平衡保护等抑制涌流影响的方法.%In HVDC system,the AC filter will produce larger inrush current during switching, which will cause damage to the filters, protection misoperation and threat to DC system security. To solve the problem, a simulation based on Monte Carlo algorithm and PSCAD user-definition model has been come up with. Make a lot of simulations about inrush current and the zero sequence current which stands for three-phase unbalanced inrush current at the inverter side. Based on these results, some methods which solve the effect of inrush current has been come up with, like erecting POW, locking the unbalanced protection temporarily.

  10. HVDC在电网发展中的应用评“灵活电力传输-HVDC的选择”一书%HVDC Applications in Power Development——Book Review on Flexible Power Transmission: The HVDC Options

    Institute of Scientific and Technical Information of China (English)

    马长林; 唐寅生

    2011-01-01

    新书“灵活电力传输-HVDC的选择”,介绍了基于AC-DC的静止换流器及高压直流输电技术,涉及的内容主要是以最新的电力电子技术改造传统的以电网换相换流( LCC)或电流源换流(CSC)为基础的高压直流(HVDC)输电系统,并对以电压源换流(VSC)为基础的柔性直流VSC-HVDC技术做了较全面的论述.评述了作者全局意译的背景与内容介绍,并以实例为佐证论述灵活电力传输HVDC在电网发展中广阔的应用前景.

  11. Study on VSC HVDC Modeling and Control Strategies for Wind Power Integration

    DEFF Research Database (Denmark)

    Korompili, Asimenia; Wu, Qiuwei

    in their applications. The main focus is given in the HVDC transmission systems, since they do not exhibit these disadvantages, whereas they additionally present beneficial attributes. This is the reason for which the applications of HVDC systems have been increased in the latest years. A brief description of different...... application cases is provided in the introduction of this report, while the rest chapters deal with the use of the HVDC technology for the grid connection of offshore wind farms. The main structure of the HVDC system is analysed, by describing the role and operation of its main components. Especially...... is performed, regarding power losses, costs, equipment aspects and control capabilities. It is concluded that the VSC-HVDC system exhibits the most advantageous features for the grid connection of offshore wind farms. In addition, various topologies of the HVDC converter stations are analysed. Furthermore...

  12. Voltage sensitivity based reactive power control on VSC-HVDC in a wind farm connected hybrid multi-infeed HVDC system

    DEFF Research Database (Denmark)

    Liu, Yan; Chen, Zhe

    2013-01-01

    With increasing application of both Line Commutated Converter based High Voltage Direct Current (LCC-HVDC) systems and Voltage Source Converter based HVDC (VSC-HVDC) links, a new type of system structure named Hybrid Multi-Infeed HVDC (HMIDC) system is formed in the modern power systems. This paper...... presents the operation and control method of the wind farm connected HMIDC system. The wind power fluctuation takes large influence to the system voltages. In order to reduce the voltage fluctuation of LCC-HVDC infeed bus caused by the wind power variation, a voltage sensitivity-based reactive power...... control method is proposed in the paper. According to the calculated sensitivity factors, a reactive power increment is added in the control loop of VSC-HVDC so as to regulate the voltage of the target bus. Dynamic simulations in PSCAD/EMTDC and MATLAB are presented to assess the performance...

  13. Steady-state and transient performance of HVDC link based 3-level ...

    African Journals Online (AJOL)

    Administrateur

    DC (HVDC) transmission systems based on three-level voltage source converters. The study involves ... active AC system at the first end & passive load at the second ..... Simulation of Back-to-Back VSC Transmission System,. Master thesis ...

  14. Dynamic modelling of VSC-HVDC for connection of offshore wind farms

    DEFF Research Database (Denmark)

    Rios, Bardo; Garcia-Valle, Rodrigo

    2011-01-01

    A VSC-HVDC (Voltage Source Converter – High Voltage Direct Current) dynamic model with a set of control strategies is developed in DIgSILENT Power-Factory with the objective of analyzing the converter’s operating capability for grid support during grid faults. The investigation is carried out based...... on a 165 MW offshore wind farm with induction generators and a Low Voltage Ride-Through solution of the offshore wind turbines and Static Voltage Compensator units in the point of connection with a grid represented by a reduced four-generator power grid model. VSC-HVDC promises to be a reliable alternative...... solution for interconnection with off-shore wind farms as they become larger, with a higher installed power capacity, increased number of wind turbines, and geographically situated at larger distances from suitable connection points in the transmission grids....

  15. Modeling of HVDC in Dynamic State Estimation Using Unscented Kalman Filter Method

    DEFF Research Database (Denmark)

    Khazraj, Hesam; Silva, Filipe Miguel Faria da; Bak, Claus Leth

    2016-01-01

    HVDC transmission is an integral part of various power system networks. This article presents an Unscented Kalman Filter dynamic state estimator algorithm that considers the presence of HVDC links. The AC - DC power flow analysis, which is implemented as power flow solver for Dynamic State...

  16. Integration of CCC-HVDC and VSC-HVDC Systems to Supply an Island Network

    Directory of Open Access Journals (Sweden)

    G.B. Gharehpetian

    2013-05-01

    Full Text Available Acombination of Capacitor Commutated Converter (CCC HVDC and voltage source converter (VSC HVDC is proposed to supply an island system without any local generation. The key point of this integration is the flat characteristic of dc voltage of CCC-HVDC, which provides the condition for VSC to connect to CCC dc link via a current regulator. The advantages of proposed combined in feeding system are requiring only one dc line and having better dynamic responses. The structure of the proposed in feeding system as well as its control system is shown in this study. The simulation results are presented to confirm the effectiveness of the proposed system. Two other schemes for in feeding the passive island systems are studied to demonstrate the advantages of the proposed system.

  17. Fault Current Limitation and Analysis of Current Limiting Characteristic for Multi-terminal VSC-HVDC DC Lines%多端VSC-HVDC直流线路故障限流及限流特性分析

    Institute of Scientific and Technical Information of China (English)

    刘剑; 邰能灵; 范春菊; 郑晓冬; 唐跃中

    2016-01-01

    基于电压源型换流器(voltage source converters,VSC)的多端柔性直流系统中直流线路的故障电流上升速度快、电流峰值大。然而具有大容量、快切断能力的高压直流断路器正在研制中。结合目前直流断路器开断容量水平,该文提出通过在直流线路两端串入限流电路的方法来限制故障电流的峰值和电流的上升速度率,并给出相关参数的理论计算方法。对该电路的限流特性进行分析与对比,结果表明,该限流电路能有效抑制故障电流,降低了对直流断路器开断容量和开断速度的要求。在该限流电路的基础上,提出一种多端VSC-HVDC 直流线路故障处理方案。仿真分析表明,该故障处理方案能够有效抑制直流线路故障电流以及 IGBT 并联二极管电流,故障切除后非故障系统能保持正常运行,可以有效地增强多端VSC-HVDC系统对直流线路故障的处理能力。%The fault current of DC line in multi-terminal HVDC system based on voltage source converters (VSC) increases quickly with large peak, while the DC circuit breaker with large capacity and fast breaking speed is still under development. Combined with the capacity level of DC circuit breaker breaking, a current limiting circuit was proposed to limit the peak and rising rate of fault current by connecting it to DC line ends. Theoretical calculation method for the circuit parameters was also given. The analysis results about the circuit and the comparison with other methods show that the proposed circuit is able to limit the fault current effectively and reduce the requirement for DC breaker capacity and speed. Based on the circuit, a fault-handling scheme for DC lines in multi-terminal VSC-HVDC was proposed. The simulation results show that the proposed scheme is capable of limiting fault current of DC lines and parallel diodes effectively, and non-fault system can maintain normal operation after fault

  18. Electrical Power Supply to Offshore Oil Installations by High Voltage Direct Current Transmission

    Energy Technology Data Exchange (ETDEWEB)

    Myhre, Joergen Chr.

    2001-07-01

    This study was initiated to investigate if it could be feasible to supply offshore oil installations in the North Sea with electrical power from land. A prestudy of alternative converter topologies indicated that the most promising solution would be to investigate a conventional system with reduced synchronous compensator rating. The study starts with a summary of the state of power supply to offshore installations today, and a short review of classical HVDC transmission. It goes on to analyse how a passive network without sources influences the inverter. The transmission, with its current controlled rectifier and large inductance, is simulated as a current source. Under these circumstances the analysis shows that the network frequency has to adapt in order to keep the active and reactive power balance until the controllers are able to react. The concept of firing angle for a thyristor is limited in a system with variable frequency, the actual control parameter is the firing delay time. Sensitivity analysis showed some astonishing consequences. The frequency rises both by an increase in the active and in the reactive load. The voltage falls by an increase in the active load, but rises by an increase in the inductive load. Two different control principles for the system of inverter, synchronous compensator and load are defined. The first takes the reference for the firing delay time from the fundamental voltage at the point of common coupling. The second takes the reference for the firing delay time from the simulated EMF of the synchronous compensator. Of these, the second is the more stable and should be chosen as the basis for a possible control system. Two simulation tools are applied. The first is a quasi-phasor model running on Matlab with Simulink. The other is a time domain model in KREAN. The time domain model is primarily used for the verification of the quasi-phasor model, and shows that quasi-phasors is still a valuable tool for making a quick analysis

  19. 基于多回直流功率转移的受端电网节假日期间电压控制%Voltage Control for Receiving End Power Grid Based on Power Transfer in Multi Infeed HVDC Transmission System During Holidays

    Institute of Scientific and Technical Information of China (English)

    缪源诚; 程浩忠; 庄侃沁

    2014-01-01

    节假日期间,电网负荷大幅下降,潮流轻载导致容性无功过剩,电压显著升高。对于多直流馈入受端电网,受直流换流站内绝对最小滤波器投入组数的制约,密集落点的多个直流换流站在直流低功率运行方式下会同时向交流电网注入大量容性无功,导致电网电压大幅升高且难以通过常规电压调整手段控制。提出了考虑多回直流功率转移的电压控制策略,在不改变直流总送电计划的基础上,通过优化分配多回直流的功率来改变直流与交流电网的无功交换数量,进而有效降低电网电压。华东电网实际案例和仿真计算均显示,在多回直流之间进行有功功率转移能有效地改善多直流馈入受端电网的无功潮流分布,合理控制系统电压。%Due to significant decrease of power load during holidays, the light load leads to the excess of capacitive reactive power and it causes the voltage rise evidently. For AC power grid located at the receiving end of multi infeed HVDC transmission system, restricted by absolute minimum number of the switched on filter banks in the HVDC converter station, under low DC power operating mode the multi HVDC converter stations, which are densely arranged in a limited area, inject a great amount capacitive reactive power simultaneously intoAC power grid located at the receiving end of multi infeed HVDC transmission system, therefore AC grid voltage significantly rises and it is hard to be controlled by conventional voltage regulation measures. A voltage control strategy, in which the DC power transfer among multi HVDC infeeds is considered, is proposed, without changing the total HVDC transmission plan, the interchanged reactive power amount between HVDC transmission system and AC power grid is changed by optimally allocating the power among multi HVDC infeeds, and further the AC grid voltage can be effectively decreased. Both actual case of East China

  20. Variable Frequency Operations of an Offshore Wind Power Plant with HVDC-VSC: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Gevorgian, V.; Singh, M.; Muljadi, E.

    2011-12-01

    In this paper, a constant Volt/Hz operation applied to the Type 1 wind turbine generator. Various control aspects of Type 1 generators at the plant level and at the turbine level will be investigated. Based on DOE study, wind power generation may reach 330 GW by 2030 at the level of penetration of 20% of the total energy production. From this amount of wind power, 54 GW of wind power will be generated at offshore wind power plants. The deployment of offshore wind power plants requires power transmission from the plant to the load center inland. Since this power transmission requires submarine cable, there is a need to use High-Voltage Direct Current (HVDC) transmission. Otherwise, if the power is transmitted via alternating current, the reactive power generated by the cable capacitance may cause an excessive over voltage in the middle of the transmission distance which requires unnecessary oversized cable voltage breakdown capability. The use of HVDC is usually required for transmission distance longer than 50 kilometers of submarine cables to be economical. The use of HVDC brings another advantage; it is capable of operating at variable frequency. The inland substation will be operated to 60 Hz synched with the grid, the offshore substation can be operated at variable frequency, thus allowing the wind power plant to be operated at constant Volt/Hz. In this paper, a constant Volt/Hz operation applied to the Type 1 wind turbine generator. Various control aspects of Type 1 generators at the plant level and at the turbine level will be investigated.

  1. Restoration of Normal Frequency Affected by Small Load Variations Through HVDC link Using Neuro-Fuzzy Approach

    OpenAIRE

    Anil Kumar Sharma,; Dr. G. K. Joshi,; Tarun Kumar De; Shyam Krishan Joshi

    2011-01-01

    HVDC power transmission is coming up with merits to replace the EHV-AC system. The controller inverter operation can successfully regulate the power in HVDC link leading to fulfillment ofpower demand in A.C. networks caused by sudden rise in loading. Since overloading and unloading both lead to the departure of operating frequency below or above normal, its control for normalization isexercised through control of power flow in HVDC Link. Also the same is achieved by adjusting firing delay ang...

  2. Improving Low Voltage Ride Through Capability of Wind Farm Grid-Connected via Dynamic Chopper Controlled Breaking Resistor Based MMC-HVDC Transmission System%含动态直流泄能电阻的MMC-HVDC提高风电场低电压穿越能力研究

    Institute of Scientific and Technical Information of China (English)

    李文津; 汤广福; 康勇

    2014-01-01

    提出了基于动态直流泄能电阻的模块化多电平柔性输电直流方案,以提高基于感应双馈电机风电场的低电压穿越能力。基于矢量控制及无源电压跟随控制分别设计了系统侧、风场侧柔性直流换流器在风电场稳态运行时的控制策略。当交流系统故障导致电压跌落时,详细分析了动态直流泄能电阻的工作原理、动作判据及导通持续时间,以实现风电场低电压穿越;同时研究了其与系统侧模块化多电平换流器在故障清除后电压恢复期的协调控制,以快速恢复风电场有功输出能力。仿真结果表明:当交流系统故障时,含动态直流泄能电阻的柔性直流输电系统能够维持直流电压且不改变风电场输出电压电流;当故障清除后,风电场输出功率恢复速率远大于电力系统行业标准相关技术指标。%A modular multilevel voltage sourced converter-based HVDC (MMC-HVDC) power transmission scheme based on dynamic chopper controlled breaking resistor (DCCBR) is proposed to improve the low-voltage ride through (LVRT) capability of wind farm composed of doubly fed induction generators (DFIG). Based on vector control and network voltage tracing control the control strategies for grid side modular multilevel converter (GSMMC) and wind farm side modular multilevel converter (WFMMC) under steady state operation of wind farm are designed respectively. Under voltage sag caused by fault in AC power grid, the working principle, operating criterion and turn-on duration time of DCCBR are analyzed in depth to realize LVRT of wind farm;meanwhile, to recover the active power output capability of wind farm rapidly the coordinated control for DCCBR and GSMMC during the voltage recovery after clearing of the fault is researched. Simulation results show that during the fault in AC power grid the flexible HVDC transmission system containing DCCBR can maintain the DC voltage of HVDC system while

  3. Design of HVDC flexible information transmission system based on CPLD%基于CPLD的柔性直流输电信息传输系统的设计

    Institute of Scientific and Technical Information of China (English)

    雍进玲; 罗鹏; 马莉

    2013-01-01

    An information transmission system based on CPLD was designed, which was used for exchaning data between HVDC flexible valve control system and submodules. By using high speed elements, designing redundancy circuit, and optimizing software algorithms, the system can run in the environment of high voltage and strong electromagnetic interference under the premise of ensuring fast response of data. The paper gives the hardware schematic diagram, the software flow chart and the test wave. The test results show that the design scheme is simple and feasible, and the system has strong anti-interference ability, which can meet the requirements of information reliable transmission of HVDC flexible system.%设计了一种基于CPLD的信息传输系统,用于柔性直流输电阀控系统与下级子模块之间的数据交换.通过采用高速元件、冗余电路设计、软件算法优化等措施,使得该系统能够在保证数据快速响应的前提下,运行在高电压和强电磁干扰环境下.给出了系统设计的硬件原理图、软件流程图和测试波形.实际测试结果表明,该设计方案简单可行、抗干扰能力强,可以满足柔性直流输电系统信息的可靠快速传输.

  4. Modelisation et simulation d'une liaison HVDC de type VSC-MMC

    Science.gov (United States)

    Saad, Hani Aziz

    High-voltage direct current transmission systems (HVDC) are rapidly expanding in the world. Two main factors are responsible for this expansion. The first is related to the difficulty of building new overhead lines to ensure the development of high-voltage AC grids, which makes the usage of underground cables more common. However, the use of such cables is limited in length to a few tens of km because of the capacitive current generated by the cable itself. Beyond this length limit, the solution is usually to transmit in DC. The second factor is related to the development of offshore wind power plants that require connecting powers of several hundred of MW to the mainland grid by cables whose lengths can reach several hundreds of km and consequently require HVDC transmission system. Several HVDC projects are currently planned and developed by the French transmission system operator RTE. One of such projects is the INELFE interconnection project, with a capacity of 2,000 MW, between France and Spain. This thesis has been funded by RTE, in order to model and simulate in off-line and real time modes, modern HVDC interconnections. The delivered simulation means are used to examine targeted HVDC system performances and risks of abnormal interactions with surrounding power systems. The particularity of the INELFE HVDC system is the usage of a dedicated control system that will largely determine the dynamic behaviour of the system for both large disturbances (faults on the network) and small perturbations (power step changes). Various VSC topologies, including the conventional two-level, multi-level diode-clamped and floating capacitor multi-level converters, have been proposed and reported in the literature. However, due to the complexity of controls and practical limitations, the VSC-HVDC system installations have been limited to the two-level and three-level diode-clamped converters. Recently, the development of modular technology called MMC (Modular Multilevel

  5. High voltage direct current modelling in optimal power flows

    Energy Technology Data Exchange (ETDEWEB)

    Ambriz-Perez, H. [Comision Federal de Electricidad, Mexico, Unidad de Ingenieria Especializada, Rio Rodano No. 14 - Piso 10, Sala 1002, Col. Cuauhtemoc, C.P. 06598, Mexico, D.F. (Mexico); Acha, E. [Department of Electronics and Electrical Engineering, University of Glasgow, Glasgow G128LT, Scotland (United Kingdom); Fuerte-Esquivel, C.R. [Faculty of Electrical Engineering, Universidad Michoacana de San Nicolas de Hidalgo, Morelia 58030, Michoacan (Mexico)

    2008-03-15

    Two-terminal high voltage direct current (HVDC) transmission links are in operation throughout the world. They are key elements in electrical power networks; their representation is oversimplified or ignored in most power system studies. This is particularly the case in Optima Power Flow (OPF) studies. Hence, an OPF program has been extended to incorporate HVDC links, taking due account of overlapping and power transfer control characteristics. This is a new development in Newton Optimal Power Flows, where the converter equations are included directly in the matrix W. The method is indeed a unified one since the solution vector is extended to accommodate the DC variables. The HVDC link model correctly takes into account the relevant DC limit variables. The impact of HVDC links on OPF studies is illustrated by numeric examples, which includes a 5-node system, the AEP 14-node and a 166-node system. (author)

  6. Method and system for a gas tube switch-based voltage source high voltage direct current transmission system

    Energy Technology Data Exchange (ETDEWEB)

    She, Xu; Chokhawala, Rahul Shantilal; Zhou, Rui; Zhang, Di; Sommerer, Timothy John; Bray, James William

    2016-12-13

    A voltage source converter based high-voltage direct-current (HVDC) transmission system includes a voltage source converter (VSC)-based power converter channel. The VSC-based power converter channel includes an AC-DC converter and a DC-AC inverter electrically coupled to the AC-DC converter. The AC-DC converter and a DC-AC inverter include at least one gas tube switching device coupled in electrical anti-parallel with a respective gas tube diode. The VSC-based power converter channel includes a commutating circuit communicatively coupled to one or more of the at least one gas tube switching devices. The commutating circuit is configured to "switch on" a respective one of the one or more gas tube switching devices during a first portion of an operational cycle and "switch off" the respective one of the one or more gas tube switching devices during a second portion of the operational cycle.

  7. Lifetime Estimation of MMC for Offshore Wind Power HVDC Application

    DEFF Research Database (Denmark)

    Liu, Hui; Ma, Ke; Qin, Zian;

    2016-01-01

    Due to a series of unique merits, Modular Multilevel Converters (MMCs) have been developing dramatically in the last decade. However in some applications like offshore power transmission the MMC modules are subjected to a variety of tough temperature profiles with adverse working condition, all......) application for offshore wind power. The mission profiles as well as the topology of the MMC are first analyzed in order to better understand the loading characteristics of MMC. Then the power loss calculation along with the electro-thermal simulation is conducted to uncover the thermal loading of MMC...... of these could lead to thermomechanical fatigues in the components and joints of the power modules and thereby causing reliability challenge. This study focuses on the lifetime evaluation of MMC based on power cycling and thermal cycling considering the mission profiles in the High Voltage Direct Current (HVDC...

  8. Lifetime Estimation of MMC for Offshore Wind Power HVDC Application

    DEFF Research Database (Denmark)

    Liu, Hui; Ma, Ke; Loh, Poh Chiang

    2014-01-01

    Due to a series of unique merits, Modular Multilevel Converters (MMCs) have been developing dramatically in the last decade. However in some applications like offshore power transmission the MMC modules are subjected to a variety of tough temperature profiles with adverse working condition, all...... of these could lead to thermo-mechanical fatigues in the components and joints of the power modules and thereby causing reliability challenge. This study focuses on the lifetime evaluation of MMC based on power cycling and thermal cycling considering the mission profiles in the High Voltage Direct Current (HVDC......) application for offshore wind power. The mission profiles as well as the topology of the MMC are first analyzed in order to better understand the loading profiles of MMC. Then the power loss calculation along with the electro-thermal simulation is conducted to uncover the thermal loading of MMC. At last...

  9. A New Approach to HVDC Grid Voltage Control Based on Generalized State Feedback

    DEFF Research Database (Denmark)

    Beerten, Jef; Eriksson, Robert; Van Hertem, Dirk

    2014-01-01

    In this paper, a new approach to DC voltage control in a High Voltage Direct Current (HVDC) grid is introduced. In an HVDC grid, the power sharing after a converter outage can be influenced by the droop control values. However, when relying on a local feedback signal, the DC voltage drops...

  10. Redundancy Determination of HVDC MMC Modules

    Directory of Open Access Journals (Sweden)

    Chanki Kim

    2015-08-01

    Full Text Available An availability and a reliability prediction has been made for a high-voltage direct-current (HVDC module of VSC (Voltage Source Converter containing DC/DC converter, gate driver, capacitor and insulated gate bipolar transistors (IGBT. This prediction was made using published failure rates for the electronic equipment. The purpose of this prediction is to determinate the additional module redundancy of VSC and the used method is “binomial failure method”.

  11. Implementation of the production management of a HVDC overlaydistribution system in the load frequency control of a three-phase-current combined systems; Integration der Betriebsfuehrung eines HGUe-Overlay-Netzes in die Leistungs-Frequenz-Regelung eines Drehstrom-Verbundnetzes

    Energy Technology Data Exchange (ETDEWEB)

    Marten, Anne-Katrin

    2012-07-01

    To reduce emission of carbon dioxide the proportion of renewable energies is rapidly growing in German and European grids in general. Additionally, the bulk of them are generated in only a few spots in European transmission grid, whereas conventional power plants will shut down and the load center distribution will still be decentralized. This results in the need of a new and powerful transmission grid, which is able to transport bulk power over long distances. To overcome this challenge one of the discussed solutions for Europe is an Overlay Network based on HVDC technology connecting spots of bulk renewable energy plants and important load centers. Because of different performance compared to an ac grid, it is necessary for an HVDC Overlay Network to actively sustain system services such as power frequency control to ensure system stability and power quality as well as the ac grid does. A novel method for realizing participation of a HVDC Overlay Network in power frequency control is presented. It hasn't only an advantage for load frequency power flows, but also for contracted balancing power flows which are also feed via the dc grid pro rata. Numerical case studies are made to show some benefits of this method in case of various disturbances. It is shown that a HVDC Overlay Network with the developed operating control releases the ac grid by an adjustable amount of power flows and improves the power frequency control for example in terms of promptness and lower frequency deviations.

  12. A Novel Modulation Function-Based Control of Modular Multilevel Converters for High Voltage Direct Current Transmission Systems

    Directory of Open Access Journals (Sweden)

    Majid Mehrasa

    2016-10-01

    Full Text Available In this paper, a novel modulation function-based method including analyses of the modulation index and phase is proposed for operation of modular multilevel converters (MMCs in high voltage direct current (HVDC transmission systems. The proposed modulation function-based control technique is developed based on thorough and precise analyses of all MMC voltages and currents in the a-b-c reference frame in which the alternating current (AC-side voltage is the first target to be obtained. Using the AC-side voltage, the combination of the MMC upper and lower arm voltages is achieved as the main structure of the proposed modulation function. The main contribution of this paper is to obtain two very simple new modulation functions to control MMC performance in different operating conditions. The features of the modulation function-based control technique are as follows: (1 this control technique is very simple and can be easily achieved in a-b-c reference frame without the need of using Park transformation; and (2 in addition, the inherent properties of the MMC model are considered in the proposed control technique. Considering these properties leads to constructing a control technique that is robust against MMC parameters changes and also is a very good tracking method for the components of MMC input currents. These features lead to improving the operation of MMC significantly, which can act as a rectifier in the HVDC structure. The simulation studies are conducted through MATLAB/SIMULINK software, and the results obtained verify the effectiveness of the proposed modulation function-based control technique.

  13. Advanced solutions in power systems HVDC, facts, and artificial intelligence

    CERN Document Server

    Liu, Chen-Ching; Edris, Abdel-Aty

    2016-01-01

    Provides insight on both classical means and new trends in the application of power electronic and artificial intelligence techniques in power system operation and control This book presents advanced solutions for power system controllability improvement, transmission capability enhancement and operation planning. The book is organized into three parts. The first part describes the CSC-HVDC and VSC-HVDC technologies, the second part presents the FACTS devices, and the third part refers to the artificial intelligence techniques. All technologies and tools approached in this book are essential for power system development to comply with the smart grid requirements.

  14. Transient analysis of an HTS DC power cable with an HVDC system

    Energy Technology Data Exchange (ETDEWEB)

    Dinh, Minh-Chau, E-mail: thanchau7787@gmail.com [Department of Electrical Engineering, Changwon National University, 9 Sarim-Dong, Changwon 641-773 (Korea, Republic of); Ju, Chang-Hyeon; Kim, Jin-Geun; Park, Minwon [Department of Electrical Engineering, Changwon National University, 9 Sarim-Dong, Changwon 641-773 (Korea, Republic of); Yu, In-Keun, E-mail: yuik@cwnu.ac.kr [Department of Electrical Engineering, Changwon National University, 9 Sarim-Dong, Changwon 641-773 (Korea, Republic of); Yang, Byeongmo [Korea Electric Power Research Institute, 105 Munji-Ro, Yuseong-Gu, Daejon 305-760 (Korea, Republic of)

    2013-11-15

    Highlights: •A model of an HTS DC power cable was developed using real time digital simulator. •The simulations of the HTS DC power cable in connection with an HVDC system were performed. •The transient analysis results of the HTS DC power cable were presented. -- Abstract: The operational characteristics of a superconducting DC power cable connected to a highvoltage direct current (HVDC) system are mainly concerned with the HVDC control and protection system. To confirm how the cable operates with the HVDC system, verifications using simulation tools are needed. This paper presents a transient analysis of a high temperature superconducting (HTS) DC power cable in connection with an HVDC system. The study was conducted via the simulation of the HVDC system and a developed model of the HTS DC power cable using a real time digital simulator (RTDS). The simulation was performed with some cases of short circuits that may have caused system damage. The simulation results show that during the faults, the quench did not happen with the HTS DC power cable because the HVDC controller reduced some degree of the fault current. These results could provide useful data for the protection design of a practical HVDC and HTS DC power cable system.

  15. 呼辽直流孤岛运行方式下送端系统频率特性及控制策略%Sending End Frequency Characteristics Under Islanded Operation Mode of HVDC Transmission System From Hulun Buir to Liaoning and Corresponding Control Strategy

    Institute of Scientific and Technical Information of China (English)

    王华伟; 韩民晓; 范园园; 吴娅妮; 张健; 雷霄

    2013-01-01

      The HVDC power transmission system from Hulun Buir to Liaoning will be fallen into islanded operation mode under following two conditions: during its normal operating mode the circuit breakers interconnecting the power plant built in the third phase of Yimin engineering with the power plants built in the first and the second phase of Yimin engineering are switched off, or the AC system at the sending end of the HVDC transmission system is disconnected from Northeast power grid due to the fault of transmission line. When the HVDC power transmission system from Hulun Buir to Liaoning is turned from normal grid-connected operational condition into islanded operational mode and when it is in the islanded operational mode, its frequency characteristics are researched. Based on generator frequency regulation, DC frequency control and corresponding security and stability measures, the frequency control strategies for the HVDC power transmission system under its normal islanded operational mode and fault condition are proposed. Simulation results show that using the proposed frequency strategies the system stability of the HVDC transmission system from Hulun Buir to Liaoning under normal and fault conditions can be ensured.%  呼伦贝尔—辽宁高压直流输电工程在正常运行方式下断开伊敏3期电厂与伊敏1、2期电厂之间的联络开关,或送端交流系统因线路故障与东北电网失去电气联系时,将进入孤岛运行。研究了呼辽直流联网转孤岛和孤岛运行时的频率特性。通过发电机调频、直流频率控制模块以及相应的安稳措施提出了呼辽孤岛正常和故障运行方式下的频率控制策略。仿真结果表明,所提出的控制措施可以保证呼辽直流正常运行和故障情况下的系统稳定性。

  16. Control and operation of wind turbine converters during faults in an offshore wind power plant grid with VSC-HVDC connection

    DEFF Research Database (Denmark)

    Chaudhary, Sanjay; Teodorescu, Remus; Rodriguez, Pedro

    2011-01-01

    ). Current limit control enables the GSC to sustain the fault currents during short circuits in the offshore wind collector system grid. However, power transmission is affected, and the fault has to be isolated. It can be resynchronized after the fault has been cleared and the breaker reclosed. Healthy WTG......Voltage source converter (VSC) based high voltage dc (HVDC) transmission is an attractive technique for large offshore wind power plants, especially when long cable transmission is required for connection to the onshore grid. New multi-MW wind turbines are likely to be equipped with full scale...

  17. Coordinated system services from offshore wind power plants connected through HVDC networks

    DEFF Research Database (Denmark)

    Zeni, Lorenzo; Glasdam, Jakob; Hesselbæk, Bo;

    2014-01-01

    This paper presents an overview of power system services in networks involving multiple onshore power systems, a voltage sourced converter (VSC) based high voltage direct current (HVDC) offshore network and an offshore wind power plant (OWPP). A comprehensive list of services regarding onshore...... to their implementation. For example, new findings on onshore AC voltage control are reported, that help the characterisation of potential AC voltage control that a VSC-HVDC station may offer to an onshore AC grid. The HVDC system behind the VSC-HVDC station may connect, through other converters, to another AC power...... system, or an OWPP, or both. Moreover, the implementation of power oscillation damping (POD) and HVDC voltage control into an OWPP controller is proposed, discussing the main challenges related to their efficient design. Dynamic control challenges are assessed, in particular in relation to the inherent...

  18. Optimal PowerFlow (OPF) Model with Unified AC-DC Load Flow and Optimal Commitmentfor an AC-catenary Railway Power Supply System (RPSS) fed by aHigh Voltage DC (HVDC) transmission line

    OpenAIRE

    Abrahamsson, Lars; Östlund, Stefan; Söder, Lennart

    2012-01-01

    In this paper an alternative railway power systems design based on an HVDC feeder is studied. The HVDC feeder is connected to the catenary by converters. Such an HVDC line is also appropriate for DC-fed railways and AC-fed railways working at public frequency. A unit commitment optimal power flow model has been developed and is applied on a test system. In this paper, the model is presented in detail. The model, in the form of an MINLP program, uses unified AC-DC power flow to minimize the en...

  19. Offshore Wind Park Connection to an HVDC Platform, without using an AC Collector Platform

    OpenAIRE

    Ahmad, Haseeb

    2012-01-01

    This thesis investigates the comparison between two different alternating current topologies of an offshore wind farms connection to an offshore high voltage direct current (HVDC) converter platform. The offshore high voltage direct current converter platform converts alternating current into direct current. Two different topologies will be investigated. In the first topology, the offshore wind farms are connected to an HVDC converter platform through offshore AC collector platform. An offsho...

  20. Design of Test Circuits of DC Circuit Breaker for High Voltage Direct Current (HVDC) Distribution System-Ⅱ%高压直流输电用直流转换开关转换电流试验回路的分析与设计(2)

    Institute of Scientific and Technical Information of China (English)

    那虎; 丁正平; 孙晋峰; 杨俊清; 刘龙开; 袁方; 洪深

    2013-01-01

    For testing the high voltage direct current (HVDC) circuit breakers of HVDC distribution system in laboratory, the working conditions and characteristics of HVDC distribution system are analyzed, and two test circuits for the HVDC circuit breakers are designed according to the grid parameters and working condition requirements, as well as PSCAD simulations. The design of one of the test circuits, named direct test circuit, is described in detail and calculated.%针对超高压直流输变电系统用的直流开关转换设备的检验检测如何在试验室实施,笔者通过对直流输电系统的运行工况及特性进行研究,依据电网参数及工况的要求定性试验方法或方式.通过对转换电流开断能力试验的相关分析及PSCAD仿真试验模拟,设计了两种试验回路以满足试验参数的要求,文中介绍其中之一合成试验回路的设计及分析,并进行计算,对其实施进行了必要的阐述和探讨.

  1. 高压直流输电用直流转换开关转换电流试验回路的分析与设计(1)%Design of Test Circuits of DC Circuit Breaker for High Voltage Direct Current(HVDC) Distribution System-Ⅰ

    Institute of Scientific and Technical Information of China (English)

    那虎; 丁正平; 孙晋峰; 杨俊清; 刘龙开; 袁方; 洪深

    2012-01-01

    For testing the high voltage direct current (HVDC) circuit breakers of HVDC distribution system in laboratory, the working conditions and characteristics of HVDC distribution system are analyzed, and two test circuits for the HVDC circuit breakers are designed according to the grid parameters and working condition requirements, as well as PSCAD simulations. The design of one of the test circuits, named direct test circuit, is described in detail and calculated.%针对超高压直流输变电系统用的直流开关转换设备的检验检测如何在试验室实施,笔者通过对直流输电系统的运行工况及特性进行研究,依据电网参数及工况的要求定性试验方法或方式.通过对转换电流开断能力试验的相关分析及PSCAD仿真试验模拟,设计了两种试验回路以满足试验参数的要求,文中介绍其中之一合成试验回路的设计及分析,并进行计算,对其实施进行了必要的阐述和探讨.

  2. Cooperative control of VSC-HVDC connected offshore wind farm with Low-Voltage Ride-Through capability

    DEFF Research Database (Denmark)

    Liu, Yan; Wang, Xiongfei; Chen, Zhe

    2012-01-01

    The Low-Voltage Ride-Through (LVRT) has become an important grid requirement for offshore wind farms connecting with Voltage Source Converter based High Voltage Direct Current (VSC-HVDC) links. In this paper, a cooperative control strategy with LVRT ability is proposed for a VSC-HVDC connected va...

  3. Control and Protection Strategies for Parallel Multi-Terminal HVDC Power Transmission System and Their Simulation%并联型多端高压直流输电系统的控制与保护策略及仿真

    Institute of Scientific and Technical Information of China (English)

    雷霄; 王华伟; 曾南超; 谢国平; 李新年; 王亮

    2012-01-01

    Multi-terminal high voltage direct current (MTDC) power transmission system can implement power transmission or power exchange between converter stations and the AC power transmission systems connecting to the formers. It can also solve the problem of power transmission while there are multi power sources or multi receiving ends. In general, the connection patterns of MTDC can be divided into two forms, i.e., the connection in parallel and the connection in series. In this paper, the steady-state operation and transient fault process of four-terminal parallel HVDC power transmission system are researched. Based on the platform of EMTDC/PSCAD a monopole simulation model is built to carry out the simulation on multi combinations of deblock startup with block-caused outage, and a DC power balance controller is designed to implement the coordinated power control among converter stations. Besides, a cooperation mode of the controller with the protection under emergency outage of single convener station or under fault occurred in DC transmission line is put forward, and simulation results show that the proposed control and protection strategies are effective.%多端高压直流(multi—terminal direct current,MTDC)输电系统可以实现各换流站所连交流系统之间的功率输送或电力交换,能够解决多电源供电或多落点受电的输电问题,其接线形式总体分为串联型与并联型。针对4端并联型高压直流输电系统进行稳态运行和暂态故障过程的相关研究,基于EMTDC/PSCAD平台建立单极仿真模型,完成了多种解锁起动和闭锁停运组合的仿真分析,设计了直流功率平衡控制器实现各换流站功率协调控制,并提出了单个换流站紧急停运以及直流线路故障时的控制保护配合方式,仿真结果表明了控制与保护策略的有效性。

  4. Short Circuit Ratio analysis of multi-infeed HVDC system with a VSC-HVDC link

    DEFF Research Database (Denmark)

    Liu, Yan; Chen, Zhe

    2011-01-01

    As an important indicator of system stability, Short Circuit Ratio (SCR) is commonly used in power system analysis. For systems include HVDC link connection, the Effective SCR (ESCR) is mostly applied to indicate the strength of HVDC infeed bus. The contribution of VSC-HVDC link to multi......-infeed HVDC system stability has been analyzed a lot but the study on ESCR of this kind of system is still insufficient. This paper presents a calculation method for ESCR of the hybrid multi infeed HVDC system based on a simple two-infeed HVDC system model. The equivalent circuit of this system under short...

  5. 一种MMC-HVDC的直流电压波动抑制新方法%A New Approach for Suppressing DC Voltage Ripples of MMC-HVDC

    Institute of Scientific and Technical Information of China (English)

    周月宾; 江道灼; 胡鹏飞; 梁一桥; 郭捷; 林志勇

    2013-01-01

    针对柔性直流输电系统常规直流电压波动抑制算法中存在的缺陷,提出一种适用于模块化多电平换流器型高压直流输电系统(modular multilevel converter based high voltage direct current,MMC-HVDC)的直流电压波动抑制方法。该方法利用MMC特有的“储能”特性,在交流系统不对称时,控制 MMC 交、直流侧瞬时有功功率不再平衡,从而实现MMC交流侧电流依然保持对称运行,同时直流侧电压、电流和功率保持为恒定。为了实现上述控制功能与目标,建立三相交流系统不对称时 MMC 直流回路的模型,设计αβ0坐标系下以比例谐振调节器为基础的控制策略,且探讨MMC-HVDC中的协调控制问题。最后,搭建71电平背靠背 MMC-HVDC 系统模型进行数字仿真,结果验证了所提控制方法的有效性。%Since the common solution for eliminating DC voltage ripples in voltage sourced converter based high voltage direct current (VSC-HVDC) transmission system has some drawbacks, this paper proposed a new method applied to modular multilevel converter based high voltage direct current (MMC-HVDC). The method uses the sub-module energy storage capability in MMC, making the instantaneous active power between ac and dc side of MMC unequal under unbalanced AC system. Meanwhile, this method keeps the ac current balanced, and eliminates the DC voltage, DC current and DC power ripples as well. To fulfill such a control goal, according to the dc-loop model of MMC, a controller inαβ0 frame based on proportional resonant regulator was designed, and then the coordinated control strategy was discussed in case of MMC-HVDC. Finally, a back-to-back MMC-HVDC simulation model with 71 levels was built to verify the proposed controller. The results show that the controller works well under both balanced and unbalanced AC system.

  6. 天生桥一广州直流系统换流阀过电压机制研究%Overvoltage Mechanism of Converter Valves for HVDC Power Transmission Project From Tianshengqiao to Guangzhou

    Institute of Scientific and Technical Information of China (English)

    陈锡磊; 周浩; 袁士超; 王东举; 田杰; 黄志岭; 卢宇

    2012-01-01

    Based on the HVDC power transmission project from Tianshengqiao to Guangzhou the mechanism leading to converter valve overvotage is analyzed and analysis results show that overvoltage will appear at both terminals of the valves under two conditions: the first one is that after turning-off all valves in uppermost layer of commutating group overvoltages appear at both terminals of the valves belonging to this layer, whereas when all valves belonging to other layers of commutating groups are turned-off there in general will not be overvotlages appearing at both terminals of these valves; the second one is that the switching surge due to interphase operation in AC-system will lead to higher overvoltage appearing at both terminals of valves. According to the analysis results, simulation analysis on two typical faults, namely the single-phase short-circuit occurred at upper-half rectifier bridge side of wye-wye connected winding of converter transformer and switching surge caused by interphase operation in AC-system, is performed. Simulation results show that when HVDC system is operated in minimum power transmission mode, the single-phase short-circuit fault occurred at upper-half rectifier bridge side of wye-wye connected winding of converter transformer will lead to higher overvotage at both terminals of valves while the energy passing through valve arrester reaches its maximum value, however, along with the increase of transmitted power the energy passing through valve arrester will decrease; in view of the fact that the transformation ratio of converter transformer configured in rectifier station is higher than that in inverter station, the swithching surge caused by interphase operations in AC system, which possess the same amplitude, will lead to relatively serious overvotlage appearing at both terminals ot converter valves in rectifier station.%基于天广±500kV高压直流输电工程,分析了阀过电压产生的机制,结果表明,在以下2种情

  7. A minimum extinction area control strategy to suppress commutation failure in HVDC transmission system%高压直流输电系统抑制换相失败的最小关断面积控制策略

    Institute of Scientific and Technical Information of China (English)

    彭忠; 李少华; 李泰; 荆雪记; 周金萍; 苏匀; 赵静; 郭宏光

    2015-01-01

    According to commutation process of inverter, the mechanism of commutation failure is analyzed. Two methods to distinguish commutation failure in HVDC transmission system are compared, which are minimum extinction angle distinguishing and minimum extinction area distinguishing. A minimum extinction area control strategy is presented to improve ability of suppressing commutation failure in inverter station. Taking Lingfeng DC project as research object, a control and protection model based on PSCAD/EMTDC is built, and control experiment with minimum extinction angle control strategy and extinction area control strategy is done. The simulation results show that minimum extinction area control strategy is more effective than minimum extinction angle control strategy in suppressing commutation failure, and commutation failure can not be avoided if AC voltage dropped seriously.%根据逆变器的换相过程,分析了换相失败机理。比较了两种高压直流输电系统换相失败判别方法:最小关断角判别和最小关断面积判别;为了提高逆变站抑制换相失败的能力,提出了最小关断面积控制策略。以林枫直流为研究对象,在PSCAD/EMTDC中建立了相应的控制保护模型,对最小关断角控制策略和最小关断面积控制策略进行对比实验。仿真结果表明最小关断面积控制策略抑制换相失败的效果优于最小关断角控制;交流电压跌落幅度过大,换相失败无法避免。

  8. Alternatives for Primary Frequency Control Contribution from Wind Power Plants Connected to VSC-HVDC Intertie

    DEFF Research Database (Denmark)

    Laukhamar, Andreas Grøsvik; Zeni, Lorenzo; Sørensen, Poul Ejnar

    how a large offshore wind power plant (OWPP) with high voltage direct current (HVDC) intertie connection to two asynchronous onshore AC power systems can be part of the solution in providing short-term mutual active power balancing. The primary frequency control is investigated for four different...... in a sharing of the primary reserves and rolling inertia between the two onshore AC power systems connected to the HVDC intertie, whilst also exploiting the OWPP in the primary frequency control scheme....

  9. Design of Harmonics-Caused Thermal Overload Protection for AC Filter Reactor and Its Application in HVDC Power Transmission Projects%交流滤波器电抗器谐波热过负荷保护设计及其在直流工程中的应用

    Institute of Scientific and Technical Information of China (English)

    张民; 贺仁睦; 李泰; 孙哲

    2013-01-01

    In HVDC power transmission projects the thermal overload of AC filter reactor may occur due to harmonic currents. The harmonics-caused thermal overload protection is the main protection for the reactor to avoid the damage due to thermal overload, so it is necessary for the correct configuraion of related protection parameters to understand the principle of this protection and master its design and implementation. The design and implementation of harmonics-caused thermal overload protection for AC filter reactor are researched in depth, and the skin-effect of harmonic currents, the determination of filter paramters, protection algorithm and setting calculation are analyzed in detail, and according to the designed withstanding ability of AC filter reactor to harmonic currents the correctness of the desing and related paramters are checked by PSCAD/EMTDC simulation. Based on the presented method and according to the skin-effect coefficient provided by reactor manufacturer the parameters of skin-effect filter can be calculated, and according to thermal equivalent current of harmonic currents the setting of the protection can be calculated. The proposed method is available for reference to the configuration of thermal overload protection for AC filter reactor used in HVDC projects.%在直流输电工程中,交流滤波器电抗器在谐波电流的作用下会出现发热或过载现象,电抗器谐波热过负荷保护是避免电抗器因过热导致损坏的主保护,理解并掌握该保护的设计原理及实现过程才能在实际工程中正确配置保护相关参数,详细研究了交流滤波器电抗器热过负荷保护的设计及实现方法,对保护中的集肤效应滤波器参数确定方法、保护算法、定值计算均进行了详细分析,并根据交流滤波器电抗器耐受谐波电流设计能力通过PSCAD/EMTDC仿真计算校核了保护设计及相关参数的正确性,在实际工程中可以按照所述方法根据电抗器生产厂

  10. Dynamic Performance of an HVDC Link

    Directory of Open Access Journals (Sweden)

    S. A. ZIDI

    2005-09-01

    Full Text Available This paper presents the results of a simulation study on a 12 pulse HVDC (High Voltage Direct Current using a system in Matlab/Simulink. The object of the study is to investigate the steady state and dynamic performance of the system. First we examine response of current regulator after change in current reference in order to see the behavior of the controllers in controlling the desired current. Next, we present the digital simulation of a test system and show the response to a DC fault in the line and the AC fault at inverter side. The results are evaluated to enhance the recovery of the system from the disturbances for a full range of typical disturbances. The presented approach benefits from Simulink’s advantages in modeling and simulating dynamical systems.

  11. HVDC Solution for Offshore Wind Park Comprising Turbines Equipped with Full-Range Converters

    DEFF Research Database (Denmark)

    Sharma, Ranjan; Rasmussen, Tonny Wederberg; Jensen, Kim Høj

    2010-01-01

    of a HVDC transmission system. The power system under study includes an offshore wind farm comprising turbines equipped with full range converters. The collection network is a local AC grid. Power transmission is done through HVDC system. The grid side VSC (voltage source converter) controls the DC voltage...... a voltage drop is created at the collection grid, the wind turbines go into fault-ride-through mode. The power output from each of the wind turbines is thus reduced to balance the system power. The detailed explanation of the strategy is presented in the paper. Matlab simulation model was prepared and some...

  12. The Applicability of Traditional Protection Methods to Lines Emanating from VSC-HVDC Interconnectors and a Novel Protection Principle

    Directory of Open Access Journals (Sweden)

    Shimin Xue

    2016-05-01

    Full Text Available Voltage source converter (VSC-based high voltage direct current (VSC-HVDC interconnectors can realize accurate and fast control of power transmission among AC networks, and provide emergency power support for AC networks. VSC-HVDC interconnectors bring exclusive fault characteristics to AC networks, thus influencing the performance of traditional protections. Since fault characteristics are related to the control schemes of interconnectors, a fault ride-through (FRT strategy which is applicable to the interconnector operating characteristic of working in four quadrants and capable of eliminating negative-sequence currents under unbalanced fault conditions is proposed first. Then, the additional terms of measured impedances of distance relays caused by fault resistances are derived using a symmetrical component method. Theoretical analysis shows the output currents of interconnectors are controllable after faults, which may cause malfunctions in distance protections installed on lines emanating from interconnectors under the effect of fault resistances. Pilot protection is also inapplicable to lines emanating from interconnectors. Furthermore, a novel pilot protection principle based on the ratio between phase currents and the ratio between negative-sequence currents flowing through both sides is proposed for lines emanating from the interconnectors whose control scheme aims at eliminating negative-sequence currents. The validity of theoretical analysis and the protection principle is verified by PSCAD/EMTDC simulations.

  13. Outline of research activity in the HVDC systems

    Energy Technology Data Exchange (ETDEWEB)

    Pigini, A.; Polo Dimel, M.; Testi, G.

    1987-05-01

    The use of HVDC lines in electric power transmission is increasing all over the world. This exceptional increase is the result of the rapid technological development in AC/DC converter stations (power electronics) and of the advantage of HVDC over AC transmission on long distances, submarine connection by means of cables, interconnection of different electric systems, easy control of flowing power, etc. Consequently, also the research and testing activities in this field are under worldwide development. However, research activities imply huge investments and the involment of a lot of personnel. Cooperation agreements such as the one between CESI and CPRI could permit the combination of efforts and the optimization of the results. In this framework, and RandD cooperation programme is on going between the CPRI and CESI (Italy) research facilities. In this paper the facilities available at CESI for carrying out research and tests in the HVDC field are presented and outlines of some studies and tests, already performed, are given. Furthermore, a review of the joint research work which is being carried out by CESI and CPRI is reported.

  14. Subsynchronous torsional interactions with static VAR compensators; Influence of HVDC

    Energy Technology Data Exchange (ETDEWEB)

    Rostamkolai, N.; Piwko, R.J.; Larsen, E.V. (General Electric Co., Schenectady, NY (USA)); Fisher, D.A. (New England Power Service Co., Westborough, MA (USA)); Mobarak, M.A. (New Brunswick Electric Power Commission, Fredericton, NB (Canada)); Poitras, A.E. (Maine Electric Power Co., Augusta, ME (US))

    1991-02-01

    Planning for installation of a static var compensator (SVC) in Chester, Maine, was initiated in 1987. The pre-specification subsynchronous torsional interaction (SSTI) studies showed the SVC might have a negative influence on stability of torsional modes of vibration of the nearby turbine-generators. In a previous paper, the parameters influencing the level of SSTI were identified with the use of a simple system. This paper extends the work to power systems containing an HVDC transmission system. The combined effect of SVC and HVDC on turbine-generator SSTI is investigated with the use of a hypothetical system. Simulation plots for the large machines of New Brunswick and Maine are included to quantify the level of interaction with the Chester SVC. Filtering as a mitigation measure is proposed to eliminate the small level of SSTI attributed to the Chester SVC.

  15. Cross-border transmission line between Nepal and India: a test-case for the analysis of HVDC integration into an existing HVAC system

    OpenAIRE

    Shrestha, Praveen

    2016-01-01

    Nepal has huge hydropower potential of 83,000 MW, of which 42,000 MW is technically and economically feasible. According to the annual report of Nepal Electricity Authority, the total installed capacity of hydropower in Nepal is only 733.57 MW. Although bestowed with tremendous hydropower resources, only about 40% of Nepal s population has access to electricity and remaining 60% faces severe load shedding. In this scenario, the cross border transmission links between Nepal and India serves t...

  16. Transient Voltage Stability Analysis of East China Receiving-End Power Grid With Multi-Infeed HVDC Transmission Lines%多直流馈入华东受端电网暂态电压稳定性分析

    Institute of Scientific and Technical Information of China (English)

    邵瑶; 汤涌; 郭小江; 周勤勇

    2011-01-01

    基于2015年“三华”特高压规划电网的丰大运行方式,利用短路比和多馈入短路比指标分析了华东受端电网的强度,并讨论了受端系统网架调整和直流系统落点位置对短路比/多馈入短路比的影响。采用PSD-BPA暂态稳定程序,分析了华东受端电网在各种故障下的暂态电压稳定性。结果表明:直流系统落点位置对华东受端电网强度的影响较大;交直流系统单一故障、受端特高压交流通道和逆变站换流母线附近线路发生三相永久性短路跳双回故障,大部分直流系统双极闭锁均不会导致华东受端电网暂态电压失稳;锦屏-同里、锡盟-金坛、复龙-奉贤和溪洛渡-浙西特高压直流发生双极闭锁故障后,送端电网需采取切机措施才能保持系统稳定。%Based on the summer peak load operation mode of the planned "North China-Central China-East China" UHV power grid in 2015, there will be 10 HVDC transmission lines feeding into East China power grid. The strength of East China receiving-end power grid is analyzed by short circuit ratio (SCR) and multi-infeed short circuit ratio (MISCR), and the impacts of network topology adjustment in receiving-end power grid and the positions where the multi-infeed DC transmission lines are connected with East China receiving-end power grid on SCR/MISCR are dissected. By use of PSD-BPA transient stability program, transient voltage stability of East China receiving-end power grid under various faults is analyzed. Analysis results show that the positions, where the multi-infeed DC transmission lines are connected with East China receiving-end power grid, greatly impacts the strength of the latter; all unipolar block faults occurred in DC systems, single faults occurred in AC/DC system, three-phase permanent short-circuit fault, which causes the tripout of two circuits, occurred in UHVAC transmission line of receiving-end system and that

  17. Power control method on VSC-HVDC in a hybrid multi-infeed HVDC system

    DEFF Research Database (Denmark)

    Liu, Yan; Chen, Zhe

    2012-01-01

    Multi-infeed HVDC (MIDC) system connected with VSC-HVDC links and LCC-HVDC links is a new structure in modern power systems, which can be called hybrid multi-infeed HVDC (HMIDC) system. The paper presents the voltage stability analysis of a HMIDC system modeled from a possible future Danish power...... stability of the system with induction machine loads. The proposed power control method based on a VSC power circle makes fully use of the VSC-HVDC capacity to support system voltage during fault situations. Simulation model of the studied HMIDC system is built in PSCAD. Simulation studies under different...

  18. Stability analysis of multi-infeed HVDC system applying VSC-HVDC

    DEFF Research Database (Denmark)

    Liu, Yan; Chen, Zhe

    2010-01-01

    on this model is analyzed under steady state and different kinds of grid fault transient situations. Two main control methods applied on VSC-HVDC link in this dual infeed HVDC system are investigated, and comparative analysis of them under transient situation is presented. A simulation model is built in PSCAD....../EMTDC to verify the theoretical analysis. Simulation results indicate that this dual infeed HVDC system can realize higher stability than single infeed HVDC system. And different control strategies on a VSC-HVDC link may result in different influence on AC voltage and active power oscillation during transient...... situation....

  19. Effects of HVDC on power systems small signal angle stability

    Energy Technology Data Exchange (ETDEWEB)

    Custodio, D.T.; Paccini, R.O.; Kopcak, I.; Costa, V.F. da [State University of Campinas (UNICAMP), SP (Brazil). School of Electrical and Computer Engineering. Power Systems Dept.], Emails: totti@dsee.fee.unicamp.br, rodrigo@dsee.fee.unicamp.br, kopcak@dsee.fee.unicamp.br, vivaldo@dsee.fee.unicamp.br

    2009-07-01

    In this paper, a didactic method for parameters tuning of the Power Oscillation Damper (POD) coupled to the HVDC constant current controller is proposed utilizing the MATLAB package with a control system toolbox. First, modal analysis is done from the system state matrix to determine the critical mode and oscillation natural frequency. Input and output linearized matrixes are built to single-input and single-output (SISO) control systems. The phase to be compensated between the active power flow in the parallel AC inter-tie and the current reference signal of the HVDC constant current controller is obtained from the Nyquist theorem. Following, the POD time constants are obtained. Finally, the static gain of the POD is tuned based on the root locus method of the classical control theory. Simulations results prove that the DC power modulation is efficient to damp the AC power oscillations. This method is straightforward because only involves matrix operation. (author)

  20. Feasibility analysis of a novel hybrid-type superconducting circuit breaker in multi-terminal HVDC networks

    Science.gov (United States)

    Khan, Umer Amir; Lee, Jong-Geon; Seo, In-Jin; Amir, Faisal; Lee, Bang-Wook

    2015-11-01

    Voltage source converter-based HVDC systems (VSC-HVDC) are a better alternative than conventional thyristor-based HVDC systems, especially for developing multi-terminal HVDC systems (MTDC). However, one of the key obstacles in developing MTDC is the absence of an adequate protection system that can quickly detect faults, locate the faulty line and trip the HVDC circuit breakers (DCCBs) to interrupt the DC fault current. In this paper, a novel hybrid-type superconducting circuit breaker (SDCCB) is proposed and feasibility analyses of its application in MTDC are presented. The SDCCB has a superconducting fault current limiter (SFCL) located in the main current path to limit fault currents until the final trip signal is received. After the trip signal the IGBT located in the main line commutates the current into a parallel line where DC current is forced to zero by the combination of IGBTs and surge arresters. Fault simulations for three-, four- and five-terminal MTDC were performed and SDCCB performance was evaluated in these MTDC. Passive current limitation by SFCL caused a significant reduction of fault current interruption stress in the SDCCB. It was observed that the DC current could change direction in MTDC after a fault and the SDCCB was modified to break the DC current in both the forward and reverse directions. The simulation results suggest that the proposed SDCCB could successfully suppress the DC fault current, cause a timely interruption, and isolate the faulty HVDC line in MTDC.

  1. Electrical and electromagnetic investigations for HVDC ground electrode sites in India

    Science.gov (United States)

    Manglik, A.; Verma, S. K.; Muralidharan, D.; Sasmal, R. P.

    High Voltage Direct Current (HVDC) power transmission systems require setting up of specially designed ground electrodes at terminal ends of the transmission line to close the circuit with an earth return path. The design parameters of these electrodes need the information about the electrical conductivity structure within a radius and depth of several km of the site in order to ensure that the injected current penetrates deep enough into the earth. Further, detailed conductivity structure, up to 100-200 m depth, of the electrode site covering an area of less than a sq. km is also needed to ensure safe limits for the step and touch potential at the site. Electrical and electromagnetic methods are very useful tools for this purpose. However, artificial source variants such as deep direct current (DC) resistivity sounding pose logistic problems for target depths greater than a couple of kilometers and in inaccessible areas. We have employed magnetotelluric (MT) and electrical resistivity tomography (ERT) tools to investigate the detailed deep and shallow electrical conductivity structure, respectively, of several potential sites in India for a ±800 kV, 6000 MW HVDC multi-terminal system. Investigations of a site in Assam revealed the presence of highly resistive crustal rocks at the depth of about 1.3 km beneath a thick pile of conductive sediments, rendering the site unsuitable even though the shallow conductivity was favorable. At another site identified after analyzing available geological and geophysical data, we inferred the presence of conductive structure up to at least 4.0 km depth. ERT investigation at this site revealed a favorable conductive structure except for the presence of a 20-m-thick near-surface resistive layer. This information has been useful for the electrode design. We suggest that a strategy suitably combining MT and ERT is useful in the selection of ground electrode sites.

  2. 76 FR 79206 - Commercial Renewable Energy Transmission on the Outer Continental Shelf (OCS) Offshore Mid...

    Science.gov (United States)

    2011-12-21

    ...), would entail the construction and installation of a two-circuit, high-voltage direct current (HVDC... energy generation facilities. These platforms would convert high-voltage alternating current into HVDC... where AWC terrestrial converter stations would convert the HVDC current to HVAC and connect to the...

  3. Grid Code Compliance – Wind farm HVDC connection

    OpenAIRE

    Västermark, Martin

    2013-01-01

    A rapid development of offshore wind power is planned in GB as a part to fulfil the EU2020 targets. 25 GW wind power capacity has been awarded to developers in nine different offshore zones outside the coast of UK. VSC-HVDC transmission is expected to be a both technical and economical favourable solution for transmitting the power into the main grid. This study investigates if such a transmission solution could comply with the regulatory framework in UK. Vattenfall and Scottish Energy Renewa...

  4. Electron transmission and quantum current distribution of C70 molecule

    Institute of Scientific and Technical Information of China (English)

    KATSUNORI; Tagami3; MASARU; Tsukada

    2008-01-01

    The characteristics of electron transmission through C70 molecule bridge in which two atomic chain leads are connected to long-axis carbon atoms are investigated theoretically by using tight-binding approach based on the Green’s function with only one π orbital electron per carbon atom. Electron transmission through C70 molecule from the input to the output terminal is obtained. From the spectrum, the switching feature of the electron transmission through C70 is found, and the oscil-lation property based on the quantized level is explained. The quantum current distributions inside C70 molecule bridge are calculated and simulated by the quan-tum current density theory based on Fisher-Lee formula at the energy point E = -0.2 eV, where the transmission spectrum shows a peak. The maximum and the mini-mum bond quantum currents are presented, and the reason why the currents are distributed nonuniformly is explained by the phase difference of the atomic orbits. The result shows that the currents at each atomic site agree with Kirchhoff quan-tum current conservation law.

  5. Tidal current turbine based on hydraulic transmission system

    Institute of Scientific and Technical Information of China (English)

    Hong-wei LIU; Wei LI; Yong-gang LIN; Shun MA

    2011-01-01

    Tidal current turbines (TCTs) are newly developed electricity generating devices.Aiming at the stabilization of the power output of TCTs,this paper introduces the hydraulic transmission technologies into TCTs.The hydrodynamics of the turbine was analyzed at first and its power output characteristics were predicted.A hydraulic power transmission system and a hydraulic pitch-controlled system were designed.Then related simulations were conducted.Finally,a TCT prototype was manufactured and tested in the workshop.The test results have confirmed the correctness of the current design and availability of installation of the hydraulic system in TCTs.

  6. Adaptive Wide-Area Damping Control for HVDC Transmission System Considering Influence of Time-Varying Delay%考虑时变时滞影响的直流广域阻尼自适应控制

    Institute of Scientific and Technical Information of China (English)

    胡楠; 李兴源; 杨毅强; 覃波

    2014-01-01

    针对交直流系统区间低频振荡问题,尤其是广域测量系统引入的时滞影响问题,利用递归最小二乘法在线辨识区间振荡主导模态,在直流附加控制抑制低频振荡机理的基础上,通过在线计算利用交流联络线功率信号进行阻尼控制的滞后相位与时变时滞造成低频振荡模态信号的滞后相位,将时域信号转化为二维旋转坐标体系中的向量信号,经过参考坐标体系的角度旋转,分别进行阻尼与时滞滞后相角的自适应补偿,结合增益放大,通过时域反变换后可得到最终补偿后的直流附加控制量。8机36节点系统仿真表明,所提设计方法能够消除时变时滞的影响,有效阻尼系统低频振荡,并且具有鲁棒性,适合在线应用。%In allusion to inter-area low-frequency oscillation occurred in AC-DC power transmission system, especially to the time delay caused by wide-area measurement system, using recursive least squares (RLS), the online identification of dominant modal of inter-area oscillation is implemented, and on the basis of suppressing low-frequency oscillation by adding supplementary control of HVDC, through the online calculation of the lagging phase caused by utilizing power signal of AC tie line transmission line for damping control and the lagging phase of low-frequency oscillation signal due to the time-varying delay, the time-domain signals are transformed into vector signals in the two dimensional rotating coordinate system, then by means of angle rotated in reference coordinate system the adaptive compensation for lagging phase due to damping control and the adaptive compensation for lagging phase due to time-varying delay are carried out respectively. Combining with gain amplification, after the inverse transformation in time-domain the post-final compensation DC supplementary controlled quantity can be obtained. Simulation results of a 8-machine 36-bus system show that the

  7. Impacts of large-scale offshore wind farm integration on power systems through VSC-HVDC

    DEFF Research Database (Denmark)

    Liu, Hongzhi; Chen, Zhe

    2013-01-01

    the impacts of integrating a large-scale offshore wind farm into the transmission system of a power grid through VSC-HVDC connection. The concerns are focused on steady-state voltage stability, dynamic voltage stability and transient angle stability. Simulation results based on an exemplary power system...

  8. Modelling and Simulation of VSC-HVDC Connection for Offshore Wind Power Plants

    DEFF Research Database (Denmark)

    Chaudhary, Sanjay Kumar; Teodorescu, Remus; Rodriguez, Pedro

    2010-01-01

    Several large offshore wind power plants (WPP) are planned in the seas around Europe. VSC-HVDC is a suitable means of integrating such large and distant offshore WPP which need long submarine cable transmission to the onshore grid. Recent trend is to use large wind turbine generators with full...

  9. DC breakdown characteristics of silicone polymer composites for HVDC insulator applications

    Science.gov (United States)

    Han, Byung-Jo; Seo, In-Jin; Seong, Jae-Kyu; Hwang, Young-Ho; Yang, Hai-Won

    2015-11-01

    Critical components for HVDC transmission systems are polymer insulators, which have stricter requirements that are more difficult to achieve compared to those of HVAC insulators. In this study, we investigated the optimal design of HVDC polymer insulators by using a DC electric field analysis and experiments. The physical properties of the polymer specimens were analyzed to develop an optimal HVDC polymer material, and four polymer specimens were prepared for DC breakdown experiments. Single and reverse polarity breakdown tests were conducted to analyze the effect of temperature on the breakdown strength of the polymer. In addition, electric fields were analyzed via simulations, in which a small-scale polymer insulator model was applied to prevent dielectric breakdown due to electric field concentration, with four DC operating conditions taken into consideration. The experimental results show that the electrical breakdown strength and the electric field distribution exhibit significant differences in relation to different DC polarity transition procedures.

  10. Application of VSC-HVDC with Shunt Connected SMES for Compensation of Power Fluctuation

    Science.gov (United States)

    Linn, Zarchi; Kakigano, Hiroaki; Miura, Yushi; Ise, Toshifumi

    This paper describes the application of VSC-HVDC (High Voltage DC Transmission using Voltage Source Converter) with shunt connected SMES (Superconducting Magnetic Energy Storage) for compensation of power fluctuation caused by fluctuating power source such as photovoltaics and wind turbines. The objectives of this proposed system is to smooth out fluctuating power in one terminal side of HVDC in order to avoid causing power system instability and frequency deviation by absorbing or providing power according to the system requirement while another terminal side power is fluctuated. The shunt connected SMES charges and discharges the energy to and from the dc side and it compensates required power of fluctuation to obtain constant power flow in one terminal side of VSC-HVDC system. This system configuration has ability for power system stabilization in the case of power fluctuation from natural energy source. PSCAD/EMTDC simulation is used to evaluate the performance of applied system configuration and control method.

  11. Total Magnetic Field Signatures over Submarine HVDC Power Cables

    Science.gov (United States)

    Johnson, R. M.; Tchernychev, M.; Johnston, J. M.; Tryggestad, J.

    2013-12-01

    Mikhail Tchernychev, Geometrics, Inc. Ross Johnson, Geometrics, Inc. Jeff Johnston, Geometrics, Inc. High Voltage Direct Current (HVDC) technology is widely used to transmit electrical power over considerable distances using submarine cables. The most commonly known examples are the HVDC cable between Italy and Greece (160 km), Victoria-Tasmania (300 km), New Jersey - Long Island (82 km) and the Transbay cable (Pittsburg, California - San-Francisco). These cables are inspected periodically and their location and burial depth verified. This inspection applies to live and idle cables; in particular a survey company could be required to locate pieces of a dead cable for subsequent removal from the sea floor. Most HVDC cables produce a constant magnetic field; therefore one of the possible survey tools would be Marine Total Field Magnetometer. We present mathematical expressions of the expected magnetic fields and compare them with fields observed during actual surveys. We also compare these anomalies fields with magnetic fields produced by other long objects, such as submarine pipelines The data processing techniques are discussed. There include the use of Analytic Signal and direct modeling of Total Magnetic Field. The Analytic Signal analysis can be adapted using ground truth where available, but the total field allows better discrimination of the cable parameters, in particular to distinguish between live and idle cable. Use of a Transverse Gradiometer (TVG) allows for easy discrimination between cable and pipe line objects. Considerable magnetic gradient is present in the case of a pipeline whereas there is less gradient for the DC power cable. Thus the TVG is used to validate assumptions made during the data interpretation process. Data obtained during the TVG surveys suggest that the magnetic field of a live HVDC cable is described by an expression for two infinite long wires carrying current in opposite directions.

  12. Feasibility analysis of a novel hybrid-type superconducting circuit breaker in multi-terminal HVDC networks

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Umer Amir [Hanyang University, Sa-3dong, Sangrok-gu, Ansan 426-791 (Korea, Republic of); National University of Sciences and Technology, PNEC Campus, Habib Rehmatullah Road, Karachi (Pakistan); Lee, Jong-Geon; Seo, In-Jin [Hanyang University, Sa-3dong, Sangrok-gu, Ansan 426-791 (Korea, Republic of); Amir, Faisal [National University of Sciences and Technology, PNEC Campus, Habib Rehmatullah Road, Karachi (Pakistan); Lee, Bang-Wook, E-mail: bangwook@hanyang.ac.kr [Hanyang University, Sa-3dong, Sangrok-gu, Ansan 426-791 (Korea, Republic of)

    2015-11-15

    Highlights: • A novel hybrid-type superconducting circuit breaker (SDCCB) is proposed. • SDCCB has SFCL located in the main current path to limit the fault current until the final trip signal. • SFCL in SDCCB suppressed the fast rising DC fault current for a predefined time. • SFCL significantly reduced the DC current breaking stress on SDCCB components. • SDCCB isolated the HVDC faulty line in three, four, and five converter stations MTDC. - Abstract: Voltage source converter-based HVDC systems (VSC-HVDC) are a better alternative than conventional thyristor-based HVDC systems, especially for developing multi-terminal HVDC systems (MTDC). However, one of the key obstacles in developing MTDC is the absence of an adequate protection system that can quickly detect faults, locate the faulty line and trip the HVDC circuit breakers (DCCBs) to interrupt the DC fault current. In this paper, a novel hybrid-type superconducting circuit breaker (SDCCB) is proposed and feasibility analyses of its application in MTDC are presented. The SDCCB has a superconducting fault current limiter (SFCL) located in the main current path to limit fault currents until the final trip signal is received. After the trip signal the IGBT located in the main line commutates the current into a parallel line where DC current is forced to zero by the combination of IGBTs and surge arresters. Fault simulations for three-, four- and five-terminal MTDC were performed and SDCCB performance was evaluated in these MTDC. Passive current limitation by SFCL caused a significant reduction of fault current interruption stress in the SDCCB. It was observed that the DC current could change direction in MTDC after a fault and the SDCCB was modified to break the DC current in both the forward and reverse directions. The simulation results suggest that the proposed SDCCB could successfully suppress the DC fault current, cause a timely interruption, and isolate the faulty HVDC line in MTDC.

  13. The Impact Study of a Statcom on Commutation Failures in an HVDC Inverter Feeding a Weak AC System

    Science.gov (United States)

    Khatir, Mohamed; Zidi, Sid-Ahmed; Fellah, Mohammed-Karim; Hadjeri, Samir; Flitti, Mohamed

    2012-03-01

    The Static Synchronous Compensator (STATCOM) devices are pure power electronics devices that use voltage source, IGBT, IGCT or GTO based converters to generate reactive current. This paper illustrates the effect of STATCOM connected whit an HVDC inverter feeding a weak AC network, on the recovery from commutation failures following AC side disturbances. MATLAB/SIMULINK simulation results have demonstrated the robust performance of the proposed system based on the first CIGRÉ HVDC Benchmark model against commutation failures.

  14. Field tests of Sub-Synchronous Oscillation damping and frequency controllers of the Rihand-Delhi HVDC bipole

    Energy Technology Data Exchange (ETDEWEB)

    Prasad, Mata [ABB, New Delhi (India); Rao, L.V.; Chakravorty, S.; Moni, R.S.; Dass, R. [National Thermal Power Corporation Ltd., New Delhi (India); Mishra, R.B.; Tripathi, D.B. [Powergrid (India); Bjorklund, Hans; Duchen, Hugo; Westling, Soren [ABB Power Systems, Ludvika (Sweden)

    1994-12-31

    The Rihand-Delhi Hvdc transmission system comprises of two poles in bipolar mode, each of 750 MW nominal capacity. The length of the transmission line is 814 km and the main objective of the link is the transmission of bulk power from the Singrauli/Rihand thermal generating complex to the major load centers near the National Capital region. As in all major Hvdc schemes, the Rihand-Delhi Hvdc project has also been provided with a SSO damping controller which was extensively tested in the simulator prior to installation. This paper describes some of the important field tests conducted to ascertain actual performance and compares the same with corresponding simulator cases. Also covered is the performance of the frequency controller. (author) 3 refs., 9 figs.

  15. Transmission Level High Temperature Superconducting Fault Current Limiter

    Energy Technology Data Exchange (ETDEWEB)

    Stewart, Gary [SuperPower, Inc., Schenectady, NY (United States)

    2016-10-05

    The primary objective of this project was to demonstrate the feasibility and reliability of utilizing high temperature superconducting (HTS) materials in a Transmission Level Superconducting Fault Current Limiter (SFCL) application. During the project, the type of high temperature superconducting material used evolved from 1st generation (1G) BSCCO-2212 melt cast bulk high temperature superconductors to 2nd generation (2G) YBCO based high temperature superconducting tape. The SFCL employed SuperPower's “Matrix” technology that offers modular features to enable scale up to transmission voltage levels. The SFCL consists of individual modules that contain elements and parallel inductors that assist in carrying the current during the fault. A number of these modules are arranged in an m x n array to form the current limiting matrix.

  16. Transmission Level High Temperature Superconducting Fault Current Limiter

    Energy Technology Data Exchange (ETDEWEB)

    Stewart, Gary [SuperPower, Inc., Schenectady, NY (United States)

    2016-10-05

    The primary objective of this project was to demonstrate the feasibility and reliability of utilizing high-temperature superconducting (HTS) materials in a Transmission Level Superconducting Fault Current Limiter (SFCL) application. During the project, the type of high-temperature superconducting material used evolved from 1st generation (1G) BSCCO-2212 melt cast bulk high-temperature superconductors to 2nd generation (2G) YBCO-based high-temperature superconducting tape. The SFCL employed SuperPower's “Matrix” technology, that offers modular features to enable scale up to transmission voltage levels. The SFCL consists of individual modules that contain elements and parallel inductors that assist in carrying the current during the fault. A number of these modules are arranged in an m x n array to form the current-limiting matrix.

  17. Power Hardware In The Loop Validation of Fault Ride Through of VSC HVDC Connected Offshore Wind Power Plants

    DEFF Research Database (Denmark)

    Sharma, Ranjan; Wu, Qiuwei; Cha, Seung-Tae;

    2014-01-01

    This paper presents the power hardware in the loop (PHIL) validation of a feed forward DC voltage control scheme for the fault ride through (FTR) of voltage source converter (VSC) high voltage DC (HVDC) connected offshore wind power plants (WPPs). In the proposed FRT scheme, the WPP collector...... network AC voltage is actively controlled by considering both the DC voltage error and the AC current from the WPP AC collector system which ensures fast and robust FRT of the VSC HVDC connected offshore WPPs. The PHIL tests were carried out in order to verify the efficacy of the proposed feed forward DC...... voltage control scheme for enhancing the FRT capability of the VSC HVDC connected WPPs. The PHIL test results have demonstrated the proper control coordination between the offshore WPP and the WPP side VSC and the efficient FRT of the VSC HVDC connected WPPs....

  18. Sliding Mode Control of Three Levels Back-To-Back VSC-HVDC System Using Space Vector Modulation

    Directory of Open Access Journals (Sweden)

    Bouafia Saber

    2014-03-01

    Full Text Available In this study, a sliding mode strategy proposed to control a three levels Back-to-Back High Voltage Direct Current (HVDC system based on the three-level voltage source converter (VSC. The voltage-balancing control of two split DC capacitors of the VSC-HVDC system is achieved using three-level space vector modulation with balancing strategy based on the effective use of the redundant switching states of the inverter voltage vectors. Finally, a complete simulation of the VSC-HVDC system validates the efficiency of the proposed strategy law. Compared to the conventional control, Sliding Mode Control scheme for the VSC-HVDC system shows the attractive advantages such as offering high tracking accuracy, fast dynamic response and good robustness.

  19. Fault Ride-Through Capability Enhancement of VSC HVDC connected Offshore Wind Power Plants

    DEFF Research Database (Denmark)

    Sharma, Ranjan; Wu, Qiuwei; Cha, Seung-Tae;

    2015-01-01

    This paper presents a feed forward direct current (DC) voltage control based fault ride-through (FRT) scheme for voltage source converter (VSC) high voltage DC (HVDC) connected offshore wind power plants (WPPs) in order to achieve active control of the WPP collector network AC voltage magnitude......, and to improve the FRT capability. During steady state operation, an open loop AC voltage control is implemented at the WPP side VSC of the HVDC system such that any possible control interactions between the WPP side VSC and the wind turbine VSC are minimized. Whereas during any grid faults, a dynamic AC voltage...... reference is applied based on both the DC voltage error and the AC active-current from the WPP collector system which ensures fast and robust FRT of the VSC HVDC connected offshore WPPs. Under unbalanced fault conditions in the host power system, the resulting oscillatory DC voltage is directly used...

  20. Centrally Coordinated Control of Multiple HVDC Links for Power Oscillation Damping

    Science.gov (United States)

    Eriksson, Robert; Söder, Lennart

    2010-06-01

    This paper presents a method of how to design a centrally coordinated controller for several HVDC links. The controller increases the damping of the power oscillations by modulating the current through the HVDC links coordinately. To design a centrally coordinated controller a reduced order open system model is estimated. The open system model of the power system is developed by using black-box system identifications techniques. The current setpoint change through the HVDC links is the set of input signals and, the speeds of the generators are the set of outputs. Numerical Algorithms for Subspace State-Space System Identification (N4SID) is used to identify a model. This controller design method increases the damping significantly which is shown for a small power system.

  1. Detailed Equivalent VSC-HVDC Modelling for Time Domain Harmonic Stability Studies in Wind Power Plants

    DEFF Research Database (Denmark)

    Glasdam, Jakob Bærholm; Bak, Claus Leth; Kocewiak, Lukasz Hubert;

    2017-01-01

    This paper presents a detailed equivalent modelling approach of the modular multi-level cascaded converter (MMCC) voltage source converter high voltage direct current (VSC-HVDC) in electromagnetic transient programs (EMTPs). The presented MMCC model will be evaluated based on comparison with the ......This paper presents a detailed equivalent modelling approach of the modular multi-level cascaded converter (MMCC) voltage source converter high voltage direct current (VSC-HVDC) in electromagnetic transient programs (EMTPs). The presented MMCC model will be evaluated based on comparison...... generators in service, as this is known to influence the harmonic stability in OWPPs. The paper demonstrates the necessity of the inclusion of a detailed equivalent model of the HVDC converter for harmonic stability studies in the time domain. By implementation of active filtering in the converters...

  2. Small signal frequency domain model of an HVDC converter

    Energy Technology Data Exchange (ETDEWEB)

    Osauskas, C.M.; Hume, D.J.; Wood, A.R. [UnIversity of Canterbury, Christchurch (New Zealand). Dept. of Electrical and Electronic Engineering

    2001-11-01

    A small-signal analytic frequency domain model of a 6-pulse HVDC converter is presented. The model consists of a set of explicit algebraic equations which relate the transfer of distortion from AC voltage, DC current and firing angle modulation, to AC current and DC voltage. The equations represent the linearisation of the transfers around a base operating point, and are derived from a piecewise linear description of the AC current and DC voltage waveforms. The model provides an understanding of the transfer of distortion by the converter and is in excellent agreement with time domain simulations. (author)

  3. HVDC System Characteristics and Simulation Models

    Energy Technology Data Exchange (ETDEWEB)

    Moon, S.I.; Han, B.M.; Jang, G.S. [Electric Enginnering and Science Research Institute, Seoul (Korea)

    2001-07-01

    This report deals with the AC-DC power system simulation method by PSS/E and EUROSTAG for the development of a strategy for the reliable operation of the Cheju-Haenam interconnected system. The simulation using both programs is performed to analyze HVDC simulation models. In addition, the control characteristics of the Cheju-Haenam HVDC system as well as Cheju AC system characteristics are described in this work. (author). 104 figs., 8 tabs.

  4. Advanced fault ride-through control of DFIG based wind turbines including grid connection via VSC-HVDC

    Energy Technology Data Exchange (ETDEWEB)

    Feltes, Christian

    2012-07-01

    With the growing renewable energy share in the power generation mix it becomes inevitable that also these new generation technologies participate on the provision of grid services to guarantee stable operation of the grid, especially when one considers the decreasing number of conventional power plants in operation as a result of the expansion of wind based generation plants. These so-called ancillary services include frequency / active power control, voltage / reactive power control and fault ride-through (FRT) with fast voltage control and are stipulated in modern grid codes. In the context of this thesis advanced control algorithms have been developed for wind turbines based on doubly-fed induction generator (DFIG) to allow safe FRT during symmetrical and unsymmetrical faults. This covers the control for conventional AC grid connection as well as for the connection through voltage source converter (VSC) based high voltage direct current transmission (HVDC). Currently, the DFIG is the most used generator technology in modem wind turbines, since it combines a relatively simple slip-ring induction machine with a frequency converter rated to only approx. 30% of the total power. This makes the DFIG a cost-effective concept, which offers a variable speed range and a high degree of flexibility in control. However, due to the direct coupling of the generator stator circuit to the grid, grid faults are a special challenge for the frequency converter, its protection circuits and control algorithms. As base for the detailed evaluation of the impact of grid faults to the DFIG, this thesis contains the analytical derivation of the DFIG short circuit currents under consideration of frequency converter control. The DFIG concept presented in this thesis makes use of a DC chopper in the frequency converter, which allows safe FRT with grid voltage support through both converter sides. The developed control contains a new algorithm for a clear separation and control of positive

  5. Connection of OWPPs to HVDC networks using VSCs and Diode Rectifiers: an Overview

    DEFF Research Database (Denmark)

    Saborío-Romano, Oscar; Bidadfar, Ali; Göksu, Ömer;

    This paper provides an overview of two technologies for connecting offshore wind power plants (offshore WPPs, OWPPs) to high-voltage direct current (HVDC) networks: voltage source converters (VSCs) and diode rectifiers (DRs). Current grid code requirements for the connection of such power plants...

  6. Real power regulation design for multi-terminal VSC-HVDC systems

    Science.gov (United States)

    Li, Guo-Jie; Ruan, Si-Ye; Lie, Tek

    2013-06-01

    A multi-terminal voltage-source-converter (VSC) based high voltage direct current (HVDC) system is concerned for its flexibility and reliability. In this study, a control strategy for multiple VSCs is proposed to auto-share the real power variation without changing control mode, which is based on "dc voltage droop" power regulation functions. With the proposed power regulation design, the multiple VSCs automatically share the real power change and the VSC-HVDC system is stable even under loss of any one converter while there is no overloading for any individual converter. Simulation results show that it is effective to balance real power for power disturbance and thus improves operation reliability for the multi-terminal VSC-HVDC system by the proposed control strategy.

  7. Review of fault diagnosis and fault-tolerant control for modular multilevel converter of HVDC

    DEFF Research Database (Denmark)

    Liu, Hui; Loh, Poh Chiang; Blaabjerg, Frede

    2013-01-01

    This review focuses on faults in Modular Multilevel Converter (MMC) for use in high voltage direct current (HVDC) systems by analyzing the vulnerable spots and failure mechanism from device to system and illustrating the control & protection methods under failure condition. At the beginning......, several typical topologies of MMC-HVDC systems are presented. Then fault types such as capacitor voltage unbalance, unbalance between upper and lower arm voltage are analyzed and the corresponding fault detection and diagnosis approaches are explained. In addition, more attention is dedicated to control...

  8. Restoration of Normal Frequency Affected by Small Load Variations Through HVDC link Using Neuro-Fuzzy Approach

    Directory of Open Access Journals (Sweden)

    Anil Kumar Sharma,

    2011-03-01

    Full Text Available HVDC power transmission is coming up with merits to replace the EHV-AC system. The controller inverter operation can successfully regulate the power in HVDC link leading to fulfillment ofpower demand in A.C. networks caused by sudden rise in loading. Since overloading and unloading both lead to the departure of operating frequency below or above normal, its control for normalization isexercised through control of power flow in HVDC Link. Also the same is achieved by adjusting firing delay angle intelligently. This paper aims at providing automation to frequency normalization after it hasundergone changes from normal value of 50 Hz, due to sudden and sustained increase in load or due to working of generations at increased loads in H.V.D.C transmission systems. It is planned to automate the restoration of departed frequency to normal value by arranging the change in firing delay angle i.e. α of the converter of H.V.D.C. link till the increased load demand is met with. An adaptive control system has been devised which controls the firing delay angle on the basis of decisions given by a fuzzy controller. Also the fuzzy controls are decided by the departure in frequency from normal. The results have been found to be encouraging.

  9. Fast isolation of faults in transmission systems using current transients

    Energy Technology Data Exchange (ETDEWEB)

    Perera, N.; Rajapakse, A.D. [University of Manitoba, Department of Electrical and Computer Engineering, Engineering Building, 15 Gillson Street, Winnipeg, Manitoba (Canada)

    2008-09-15

    This paper presents a protection scheme that is capable of very fast isolation of faults in high voltage transmission systems. Proposed scheme comprises set of relays connected through a telecommunication network, located at different nodes of the system. Relays use wavelet coefficients of current signals to identify the fault directions relative to their location. Fault directions identified at different locations in the system can be combined to determine the faulted line (or busbar) and isolate it. A robust single ended traveling wave based fault distance estimation approach is proposed as a backup in case of communication failure. Investigations were carried out using time domain simulations in PSCAD/EMTDC for a high voltage transmission system. (author)

  10. Analysis of auto-sequence control and influence of three power transmission modes in Yongren-Funing HVDC Project%永仁-富宁直流工程三种功率输送方式自动转换顺序控制及影响分析

    Institute of Scientific and Technical Information of China (English)

    刘毅力; 贾轩涛; 戴国安; 张爱玲; 孔令凯; 周玉勇; 刘旭辉

    2015-01-01

    In the field of HVDC transmission, DC power can be transmitted to different AC asynchronous electrical network. The present DC control and protection function can not fulfil the new power transmission mode; based on different modes, new functions should be added in control and protection systems, such as RPC selecting logic, etc. And it’s important to HVDC transmission stable operation. As a result, based on the working condition of DC system and the configration of AC switch yard at inverter station, the auto-switch-over theory of different DC power transmission modes and the process and interlocking are analyzed; the influence on reactive power control, last line/last circuit breaker, and the AC busbar over voltage are researched. The technology of research, and the design logic has reference value for the similar projects.%在直流输电领域,逆变站可以将直流功率直接输送到不同的异步电网,目前的直流控制保护功能无法满足这种新的功率输送模式。针对不同的功率输送模式,控制系统必须具备自动判别和顺序控制功能,并选择正确的无功控制等逻辑,这对直流系统的稳定运行至关重要。为此,基于直流系统的运行工况和逆变站交流场开关配置,系统分析了不同功率输送模式间自动转换的原理、过程和联锁条件,研究了在直流解锁工况下进行在线转换时对无功控制、最后断路器/线路保护、交流母线过电压保护的影响。研发的技术、设计的直流控制保护逻辑对今后的类似工程具有参考价值。

  11. Novel control strategies of HVDC system with self-commutated converter. Jireishiki henkanki wo tekiyoshita HVDC sytem ni okeru tanshi seigyo to kyocho seigyo

    Energy Technology Data Exchange (ETDEWEB)

    Tokiwa, Y.; Ichikawa, F.; Suzuki, K. (Tokyo Electric Power Co. Inc., Tokyo (Japan)); Inokuchi, H.; Hirose, S.; Kimura, K. (Toshiba Corp., Tokyo (Japan))

    1992-01-20

    This report describes new control strategies of a self -commutated converter applied to the HVDC systems; that is, the cooperative control for a two-terminal transmission system and the terminal control which is applicable to a multi-terminal system. The DC voltage control with an upper and lower power-limiter showed excellent characteristics when applied to the two- terminal transmission system. A voltage margin method was also introduced as a power flow reversal method. These terminal control methods, if required, are able to change interchange power at the receiving end in the case of fault in the communication system. Moreover, the DC voltage control with two-stage voltage control characteristics was proposed for the multi-terminal HVDC system. with this mehtod, the DC transmission system can be operated continuously and stably cooperating electric power at each terminal even when one terminal is collapsed. The terminal control performance in the above two-terminal HVDC system was tested with a simulator. The result showed favorable performance characteristics at the time of power flow reversal and one terminal start-up during other terminal operation. 5 refs., 16 figs.

  12. Droop Control Strategy for Wind Power Decentralized Integration Based on VSC-HVDC Systems%基于 VSC-HVDC 的风电分散并网下垂控制策略

    Institute of Scientific and Technical Information of China (English)

    田园园; 廖清芬; 刘涤尘; 彭思成; 邹宏亮

    2016-01-01

    With the large-scale development of offshore wind power,the voltage source converter based high voltage direct current(VSC-HVDC) transmission system has received extensive attention in recent years.By introducing the AC voltage droop control,a coordinated multi-terminal grid-connection control strategy for a wind farm AC-dispersed at the sending end based on VSC-HVDC systems is proposed.Based on the traditional control strategy for the flexible HVDC transmission system,the DC voltage control of inverters on the grid side is retained to guarantee system power balance,while AC voltage droop control rather than the original constant-power control is designed for the rectifier on the wind farm side to achieve the advantage of communication-free and reasonable dynamic allocation.Simulation analysis shows that the control strategy proposed is not only able to achieve flexible automatic tracking of rated active power,but also has certain tolerance of load fluctuation and the function of DC/AC fault isolation.And when it comes to power supply for multi-terminal distribution networks by a wind farm AC-dispersed at the sending end,quick power reversal can be achieved if the wind farm is cut out of the system to ensure power supply reliability.And the system is capable of realizing rational allocation of dynamic power automatically among them according to rated ratio,providing effective solutions for coordinated operation of wind farm”s decentralized integration into distribution networks.%海上风电的大规模开发使得柔性直流(VSC-HVDC)输电技术得到了越来越广泛的关注与应用。文中通过引入交流电压下垂控制,提出了基于 VSC-HVDC 的适应送端交流分散模式下的风电场多端并网的协调控制策略。在柔性直流输电传统控制策略的基础上,保留配电网侧逆变器的定直流电压控制,以保证系统功率平衡;而使风电场侧整流器采用交流电压下垂控制,以代替原有的恒功

  13. Optimal dynamic capacity allocation of HVDC interconnections for cross-border exchange of balancing services in presence of uncertainty

    DEFF Research Database (Denmark)

    Delikaraoglou, Stefanos; Pinson, Pierre; Eriksson, Robert

    2015-01-01

    of the power system depends both on the technical parameters of its components, i.e., generators and transmission infrastructure, as well as on the operational practices that make optimal use of the available assets. This work focuses on alternative market designs that enable sharing of cross-border balancing...... and the uncertainty arising from their partial predictability. Considering that the existing setup of the European electricity markets promotes the spatial coordination of neighbouring power systems only on the day-ahead market stage, regional system operators have to rely mainly on their internal balancing resources...... resources between adjacent power systems through High Voltage Direct Current (HVDC) interconnections which provide increased controllability. In this context, we formulate a stochastic market-clearing algorithm that attains full spatio-temporal integration of reserve capacity, day-ahead and balancing...

  14. Automatic Generation Control in Multi Area Interconnected Power System by using HVDC Links

    Directory of Open Access Journals (Sweden)

    Yogendra Arya

    2012-01-01

    Full Text Available This paper investigates the effects of HVDC link in parallel with HVAC link on automatic generation control (AGC problem for a multi-area power system taking into consideration system parameter variations. A fuzzy logic controller is proposed for four area power system interconnected via parallel HVAC/HVDC transmission link which is also referred as asynchronous tie-lines. The linear model of HVAC/HVDC link is developed and the system responses to sudden load change are studied. The simulation studies are carried out for a four area interconnected thermal power system. Suitable solution for automatic generation control problem of four area electrical power system is obtained by means of improving the dynamic performance of power system under study. Robustness of controller is also checked by varying parameters. Simulation results indicate that the scheme works well. The dynamic analyses have been done with and without HVDC link using fuzzy logic controller in Matlab-Simulink. Further a comparison between the two is presented and it has been shown that the performance of the proposed scheme is superior in terms of overshoot and settling time.

  15. 混合双馈入直流系统中VSC-HVDC对LCC-HVDC受端系统强度的影响%The Effects of VSC-HVDC on the System Strength of LCC-HVDC in Dual-infeed Hybrid HVDC System

    Institute of Scientific and Technical Information of China (English)

    倪晓军; 赵成勇; 郭春义; 刘羽超

    2015-01-01

    为了准确评估混合双馈入直流系统中电网换相换流器高压直流输电(line commutated converter based high voltage direct current,LCC-HVDC)子系统的受端系统强度,对LCC-HVDC 子系统的有效短路比进行研究。第一,基于牛顿最优潮流算法,分析混合双馈入直流系统中电压源换流器高压直流输电(voltage source converter based HVDC, VSC-HVDC)子系统采用不同的功率输送方向和控制方式时,对LCC-HVDC子系统的交流系统电压支撑强度的影响关系。第二,计算VSC-HVDC子系统的等效阻抗,提出能够有效评估混合双馈入系统中LCC-HVDC子系统有效短路比的等值有效短路比指标。利用该指标可将混合双馈入直流系统中LCC-HVDC子系统等效为受端交流系统电压支撑强度与之相同的单馈入直流输电系统。最后,基于 PSCAD/ EMTDC进行仿真分析,仿真结果证明了VSC-HVDC对LCC-HVDC 子系统影响关系的正确性以及等值有效短路比指标的有效性。%The effective short circuit ratio of line commutated converter based high voltage direct current (LCC-HVDC) sub-system in dual-infeed hybrid HVDC system was investigated to evaluate the system strength of LCC-HVDC. Firstly, the voltage support strength of AC system was analyzed when different power flow directions and different controled strategies were adopted in voltage source converter (VSC) based on optimal power flow by Newton approach. Secondly, the equivalent impedance of VSC-HVDC was calculated, and the effective short circuit ratio of the LCC-HVDC was quantified by a proposed “equivalent effective short circuit ratio” index. The LCC-HVDC in dual-infeed hybrid HVDC system could be equivalent to a single-infeed HVDC system which had the same voltage support strength by the index. Simulation results in PSCAD/EMTDC show that the analysis on the effects of VSC-HVDC to LCC-HVDC proved to be accurate and the “equivalent effective short circuit ratio” index is

  16. 500-kV HVDC air-blast circuit breaker. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Bachman, B.; Ruoss, E.

    1986-08-01

    This report describes the first HVDC circuit breaker to be tested on a full-scale utility system. Modular in construction to ensure economic feasibility, this breaker has a standard ac air-blast breaker as its main component and interrupts current up to 2200-A dc.

  17. A transmission-loss monitor using current transformers

    Energy Technology Data Exchange (ETDEWEB)

    Power, J.F.; Gilpatrick, J.D.; Jason, A.J.

    1993-12-01

    A system for measuring the amount of beam-charge loss in a linear-accelerator structure has been developed that uses a pair of beam-current transformers, otherwise used to monitor the linac beam current. This system is necessary to enable the Ground Test Accelerator (GTA) fast-protect system to shut off the accelerated beam in the event of a beam loss that would deposit sufficient energy to damage the accelerator structure. The present GTA accelerator consists of a 2.5-MeV, H{sup {minus}} RFQ, an intermediate matching section (IMS) and a single DTL cavity with an output energy of 3.2-MeV and transmitted current of 35 mA. Based on the RFQ output beam, melting of the copper structures will occur when about 40 nC of beam is deposited in a point loss. For a grazing angle of 30 mrad, up to 640 nC may be tolerated. The beam-current-transmission-loss monitor (BCTLM) system in conjunction with the fast-protect system measures the amount of beam loss between two toroidal beam-current monitors and automatically terminates the macropulse when the integrated loss reaches a predetermined set point. The design and operation of the BCTLM system used in the IMS and DTL section of the accelerator is described.

  18. Renewable Energy in Eastern North Africa in Terms of Patterns of Coupling to Czisch European HVDC Super Grid

    Directory of Open Access Journals (Sweden)

    K Boubaker

    2013-06-01

    Full Text Available In this study, wind energy potential and perspectives in the eastern North Africa region (Tunisia have been investigated in terms of connectivity to the projected Czisch European HVDC super grid. A simplified extracted scheme of this grid has been used as a guide to optimize transportation efficiency through the whole net. Wind, as an available and easily exploitable renewable energy was showing to have a promising future for 2025 horizon in the context of a connected net with the European Union, despite local sub-grids disparities. This is also to emphasis HVDC technology adequacy for economical power transmission over very long distances andconnection between differently established grids.

  19. Modelling and Simulation of VSC-HVDC Connection for Wind Power Plants

    DEFF Research Database (Denmark)

    Chaudhary, Sanjay Kumar; Teodorescu, Remus; Rodriguez, Pedro;

    2009-01-01

    This paper describes the modelling and simulation of offshore wind power plants (WPP) connected to the onshore power system grid by VSC based HVDC transmission. Offshore wind power plant is modelled with several wind turbine generators connected to two separate collector buses with their own plant...... step-up transformers. VSC's are modelled using ideal IGBT switches supplied by the gate pulses from their respective controllers. A sequence of operation has been simulated from the starting up of the VSC-HVDC transmission, energizing the offshore grid and subsequent synchronization of the individual...... wind turbines. Simulation of power ramping up and down as well as steady state operation has been demonstrated. As an additional case, the primary reserve control logic has been implemented and simulated in PSCAD model....

  20. Integration of offshore wind farms through high voltage direct current networks

    Science.gov (United States)

    Livermore, Luke

    The integration of offshore wind farms through Multi Terminal DC (MTDC) networks into the GB network was investigated. The ability of Voltage Source Converter (VSC) High Voltage Direct Current (HVDC) to damp Subsynchronous Resonance (SSR) and ride through onshore AC faults was studied. Due to increased levels of wind generation in Scotland, substantial onshore and offshore reinforcements to the GB transmission network are proposed. Possible inland reinforcements include the use of series compensation through fixed capacitors. This potentially can lead to SSR. Offshore reinforcements are proposed by two HVDC links. In addition to its primary functions of bulk power transmission, a HVDC link can be used to provide damping against SSR, and this function has been modelled. Simulation studies have been carried out in PSCAD. In addition, a real-time hardware-in-the-loop HVDC test rig has been used to implement and validate the proposed damping scheme on an experimental platform. When faults occur within AC onshore networks, offshore MTDC networks are vulnerable to DC overvoltages, potentially damaging the DC plant and cables. Power reduction and power dissipation control systems were investigated to ride through onshore AC faults. These methods do not require dedicated fast communication systems. Simulations and laboratory experiments are carried out to evaluate the control systems, with the results from the two platforms compared..

  1. Tailoring of electron flow current in magnetically insulated transmission lines

    Directory of Open Access Journals (Sweden)

    J. P. Martin

    2009-03-01

    Full Text Available It is desirable to optimize (minimizing both the inductance and electron flow the magnetically insulated vacuum sections of low impedance pulsed-power drivers. The goal of low inductance is understandable from basic efficiency arguments. The goal of low electron flow results from two observations: (1 flowing electrons generally do not deliver energy to (or even reach most loads, and thus constitute a loss mechanism; (2 energetic electrons deposited in a small area can cause anode damage and anode plasma formation. Low inductance and low electron flow are competing goals; an optimized system requires a balance of the two. While magnetically insulated systems are generally forgiving, there are times when optimization is crucial. For example, in large pulsed-power drivers used to energize high energy density physics loads, the electron flow as a fraction of total current is small, but that flow often reaches the anode in relatively small regions. If the anode temperature becomes high enough to desorb gas, the resulting plasma initiates a gap closure process that can impact system performance. Magnetic-pressure driven (z pinches and material equation of state loads behave like a fixed inductor for much of the drive pulse. It is clear that neither fixed gap nor constant-impedance transmission lines are optimal for driving inductive loads. This work shows a technique for developing the optimal impedance profile for the magnetically insulated section of a high-current driver. Particle-in-cell calculations are used to validate the impedance profiles developed in a radial disk magnetically insulated transmission line geometry. The input parameters are the spacing and location of the minimum gap, the effective load inductance, and the desired electron flow profile. The radial electron flow profiles from these simulations are in good agreement with theoretical predictions when driven at relatively high voltage (i.e., V≥2  MV.

  2. Fault Ride-through Capability Enhancement of VSC-HVDC-connected Offshore Wind Power Plants

    Institute of Scientific and Technical Information of China (English)

    Ranjan SHARMA; Qiuwei WU; Seung Tae CHA; Kim Høj ENSEN; Tony Wederberg RASMUSSEN; Jacob ØSTERGAARD

    2015-01-01

    To achieve active control of the AC voltage magnitude of wind power plant(WPP) collector network and improve the fault ride-through (FRT) capability,an FRT scheme based on feed forward DC voltage control is presented for voltage source converter-high voltage direct current(VSC-HVDC) connected offshore WPPs.During steady state operation,an open loop AC voltage control is implemented at the WPP-side VSC of the HVDC system so that any possible control interactions between WPP-side VSC and VSC of wind turbine are minimized.Whereas during any grid fault,a dynamic AC voltage reference is made according to both the DC voltage error and AC active current from the WPP collector system,thus ensuring fast and robust FRT of the VSC-HVDC-connected offshore WPPs.Under the unbalanced fault condition in the host power system,the resulting oscillatory DC voltage is directly used in the VSC AC voltage controller at the WPP side so that the WPP collector system voltage also reflects the unbalance in the main grid.Time domain simulations are performed to verify the efficacy of the FRT scheme based on the proposed feed forward DC voltage control.Simulation results show satisfactory FRT responses of the VSC-HVDC-connected offshore WPP under balanced and unbalanced faults in the host power system,as is shown under a serious fault in the WPP collector network.

  3. Power Flow Algorithm of Multi-Terminal VSC-HVDC System Based on Nodal Current Relation%基于节点电流关系的多端柔性直流输电系统潮流计算

    Institute of Scientific and Technical Information of China (English)

    钱甜甜; 苗世洪

    2016-01-01

    多端柔性直流输电系统是近年来的研究热点,而关于其潮流计算的研究是系统稳定控制和故障分析的基础,迄今为止,已有很多文献对此做了研究,但从其使用的求解潮流的数学模型方面看,都是基于节点功率关系的。提出了一种基于节点电流关系的多端柔性直流网络潮流算法,且考虑了下垂控制方式,以6节点直流网络和11节点交直流混联网络为例,在 Matlab 中编制了相应的程序,并与现有文献中的基于节点功率关系的潮流算法做了对比。对比结果显示,在不同的网络运行方式下达到相同的预定计算精度时,均比基于节点功率关系的潮流算法迭代次数少,所用时间短且当节点电压初值发生一系列变化时,所提算法依然可以快速求解出收敛解,而基于节点功率关系的算法,对于电压初值变化很敏感,迭代次数随初值的变化而变化。算例结果表明,所提算法对含有多端柔性直流系统的网络潮流计算具有较好的快速性和计算精度。%Multi-terminal VSC-HVDC (voltage source converter-high voltage direct current) system is research hotspot in recent years. Its power flow calculation is basis of system stability control and fault analysis. Many references have performed researches on this topic. In term of mathematical model of power flow calculation, most references are based on nodal power relations. Power flow calculation model based on nodal current relation is proposed in this paper and voltage droop control is considered. A 6-node DC network and an 11-node AC-DC hybrid network are taken as examples and power flow calculation codes are compiled in MATLAB. Compared with power flow calculation results based on nodal power relation, the proposed method is easier to realize and needs less iterations in various operation modes with higher accuracy. When initial node voltage value changes, the proposed algorithm is

  4. 特高压直流分层接入方式在多馈入直流电网的应用研究%Study on the Application of UHVDC Hierarchical Connection Mode to Multi-infeed HVDC System

    Institute of Scientific and Technical Information of China (English)

    刘振亚; 秦晓辉; 赵良; 赵庆波

    2013-01-01

    随着我国特高压交直流技术的广泛应用,多馈入直流集中落入受端负荷中心将是未来我国电网发展所面临的重要问题.为从电网结构上有效解决多馈入直流系统的问题,提出一种特高压直流分层接入交流电网的方式.研究分层接入方式直流多馈入短路比计算方法的适用性,从理论上对比特高压直流不同接入方式下多馈入直流电网的系统特性,证明特高压直流分层接入方式有助于提高多馈入直流系统的电压支撑能力,引导潮流在1 000 kV与500 kV层级间合理分布.结合国家电网规划,仿真验证了特高压直流分层接入方式的优势.%With the development and widespread use of ultra high-voltage alternate current (UHVAC) and ultra high-voltage direct current (UHVDC) transmission technology, the multi-infeed HVDC system in load center of China will be the prominent problem in the development of China power grids. The paper is focused on addressing the technical problems in multi-infeed HVDC system effectively from the aspect of grid structure. Firstly, a novel UHVDC hierarchical connection mode was proposed. Secondly, the applicability of the M1SCR (multi-infeed short circuit ratio) calculation formula to the hierarchical connection mode was studied. Thirdly, the system characteristics of multi-infeed HVDC system under different UHVDC connection modes were studied and compared theoretically, and it was proved that the UHVDC hierarchical connection mode was helpful to increase the voltage support capability of multi-infeed HVDC system, and it was beneficial to enable the reasonable power flow distribution between the 1 000 kV layer and 500 kV layer in the multi-infeed HVDC system. Finally, the power grid plan scheme in 2020 taken as an example, the simulation was carried out and the advantage of UHVDC hierarchical connection mode was verified.

  5. Research on Effects of Conductor Arrangements on Surface Field Strength of Conductor in ± 500kV HVDC Transmission Line%±500kV直流线路导线布置对导线表面电场强度的影响

    Institute of Scientific and Technical Information of China (English)

    陶优

    2015-01-01

    The surface field strength of a conductor depends on the running voltage, the diameter of sub-conductor, the number of bundled conductor, bundled wire pitch, The height of conductor, phase-to-phase distance, etc. The surface field strength of the conductor used in a ± 500kV HVDC Transmission Line is calculated. The result shows that the field strength is affected more by the number of bundled conductor and the diameter of sub-conductor and less by the height of the conductor and the bundled wire pitch.%导线表面电场强度取决于运行电压、子导线直径、分裂数、分裂间距、导线高度以及相间距离等。对±500kV直流线路导线表面电场强度进行计算,结果显示,导线表面电场强度受导线分裂根数、子导线直径的影响较大,导线高度和导线分裂间距影响较小。

  6. Modeling of Pressure Effects in HVDC Cables

    DEFF Research Database (Denmark)

    Szabo, Peter; Hassager, Ole; Strøbech, Esben

    1999-01-01

    A model is developed for the prediction of pressure effects in HVDC mass impregnatedcables as a result of temperature changes.To test the model assumptions, experiments were performed in cable like geometries.It is concluded that the model may predict the formation of gas cavities....

  7. Present trends in HVDC converter station design

    Energy Technology Data Exchange (ETDEWEB)

    Carlsson, Lennart; Asplund, Gunnar; Bjorklund, Hans; Flisberg, Gunnar [ABB Power Systems AB, Ludvika (Sweden)

    1994-12-31

    HVDC converter station technology has developed rapidly to satisfy increasing requirements during past 10 - 15 years, but there has not been any dramatic changes since thyristor valves were introduced in the mid 70s. This paper describes some recent and expected future developments, that will substantiality change and simplify future converter stations. (author) 4 refs., 7 figs.

  8. Coordinated control of wind power plants in offshore HVDC grids

    DEFF Research Database (Denmark)

    Sakamuri, Jayachandra N.

    2017-01-01

    During the recent years, there has been a significant penetration of offshore wind power into the power system and this trend is expected to continue in the future. The North Sea in Europe has higher potential for offshore wind power; therefore, the North Seas Countries' Offshore Grid initiative...... power between different countries, and different synchronous areas. It is very likely that they will then be combined with offshore wind power plant (OWPP) connections in the North Sea, transforming it in a multi terminal DC (MTDC) grid and, therefore, in a fully meshed offshore DC grid in near future...... was formed among nine North Sea countries. They agreed on closer energy cooperation to enable development of an efficient and economic offshore grid infrastructure for advantages, interconnectors based on the voltage source converter based high voltage DC (HVDC) transmission system is being used to exchange...

  9. A Hybrid HVDC System With DC Fault Ride-through Capability%一种具有直流故障穿越能力的混合直流输电系统

    Institute of Scientific and Technical Information of China (English)

    郭春义; 赵成勇; 彭茂兰; 刘炜

    2015-01-01

    针对一种整流侧采用电网换相换流器(line commutated converter,LCC)、逆变侧采用LCC与模块化多电平换流器(modular multilevel converter,MMC)串联的混合直流输电拓扑结构进行研究,建立混合直流输电系统模型,推导稳态数学模型,设计系统协调控制策略,并分析其穿越直流故障的机理。在PSCAD/EMTDC仿真环境下搭建混合直流输电的模型,对系统的启动、稳态、交流故障及直流故障穿越特性进行研究。仿真结果表明:系统具有良好的启动和稳态特性; MMC可改善逆变侧交流系统电压稳定性,降低换相失败发生的概率;系统具有直流故障穿越与快速恢复的特性,适用于架空线路输电的场合。%This paper investigated a hybrid high voltage direct current (HVDC) system, in which the rectifier adopts line commutated converter (LCC) and the inverter was composed by LCC in series with the modular multilevel converter (MMC). The model of this hybrid HVDC system was developed, steady-state mathematical model was deduced, the coordinated control strategy was designed, and the DC fault ride-through capability was analyzed in this paper. The hybrid HVDC system was built in the PSCAD/EMTDC simulation environment. Simulation results show that the hybrid HVDC system possesses favorable start-up and steady performances, the risk of commutation failure is reduced due to the effective regulation of inverter AC busbar voltage by MMC, and the hybrid HVDC system possesses the DC fault ride-through and quick recovery capability, which can be applied for the overhead line transmission.

  10. High Voltage Power Transmission for Wind Energy

    Science.gov (United States)

    Kim, Young il

    The high wind speeds and wide available area at sea have recently increased the interests on offshore wind farms in the U.S.A. As offshore wind farms become larger and are placed further from the shore, the power transmission to the onshore grid becomes a key feature. Power transmission of the offshore wind farm, in which good wind conditions and a larger installation area than an onshore site are available, requires the use of submarine cable systems. Therefore, an underground power cable system requires unique design and installation challenges not found in the overhead power cable environment. This paper presents analysis about the benefit and drawbacks of three different transmission solutions: HVAC, LCC/VSC HVDC in the grid connecting offshore wind farms and also analyzed the electrical characteristics of underground cables. In particular, loss of HV (High Voltage) subsea power of the transmission cables was evaluated by the Brakelmann's theory, taking into account the distributions of current and temperature.

  11. A Quantitative Evaluation Method on Interaction Analysis of Hybrid Multi-infeed HVDC System%混合多馈入直流输电系统相互作用关系的定量评估方法

    Institute of Scientific and Technical Information of China (English)

    郭春义; 倪晓军; 赵成勇

    2016-01-01

    Apparent increase in short circuit ratio (AISCR) is an index to quantitatively evaluate the impact of voltage source converter based high voltage direct current (VSC-HVDC) on line commutated converter based high voltage direct current (LCC-HVDC) in hybrid mutli-infeed HVDC system. Based on the AISCR index, the impact of VSC-HVDC on LCC-HVDC was further studied considering different power flow direction of VSC-HVDC link. Then, the transient performances of LCC-HVDC, such as transient over-voltage, commutation failure immunity and fault recovery performances, were investigated in PSCAD/EMTDC software, when VSC operates as rectifier or inverter. Considering the electric distance between VSC-HVDC and LCC-HVDC, the trend of AISCR was calculated with varying distance. Finally, the coupling effects of AC system and VSC-HVDC on AISCR of LCC-HVDC were decoupled, and the AISCR impacted by VSC-HVDC only, without the impact of AC system, was obtained. The conclusions got could provide valuable theoretical guide for capacity and feed-in location selection of VSC-HVDC in hybrid multi-infeed HVDC system.%视在短路比增加量(apparent increase in short circuit ratio,AISCR)是一种定量评估混合多馈入系统中电压源换流器型高压直流输电(voltage source converter based high voltage direct current,VSC-HVDC)对电网换相换流器高压直流输电(line commutated converter based high voltage direct current,LCC-HVDC)运行特性影响关系的指标,该文基于AISCR指标,定量评估混合双馈入系统中当VSC-HVDC潮流方向不同时对LCC-HVDC运行特性的影响,在此基础上基于PSCAD/EMTDC对比分析VSC分别作为整流运行和逆变运行时LCC-HVDC的暂态过电压、换相失败抵御能力、故障恢复等暂态运行特性。研究当 VSC-HVDC 与LCC-HVDC之间存在电气距离的情况下AISCR随着电气距离的变化趋势;最后将交流系统与 VSC-HVDC 对LCC-HVDC 视在短路比增加量的耦合作用进行了

  12. Coordination Control Strategy for Compound Fault of MMC-HVDC

    Directory of Open Access Journals (Sweden)

    Zhang Ming Guang

    2016-01-01

    Full Text Available Single-line to ground fault of DC side and sub-module fault are typical faults of MMC-HVDC. When each of the above faults occurs, the system will give a signal for circuit-breaker releasing, this will result in interruption of power delivery, the stability of the system is greatly reduced. When these two faults occur simultaneously, research on control strategy for compound fault will help to improve the reliability of the system. While single-line to ground fault of DC side happens, only the electric potential auxiliary point of DC side is changed, system’s power transport normally. When sub-module is fault, redundancy fault-tolerated control strategy is presented, which replace the failed sub-modules with equal number of redundant sub-modules, it can restrain the fluctuation of direct current. A double terminals and 21 voltage-level MMC-HVDC system simulation model is set up in PSCAD/EMTDC. From the computation and simulation results, it is concluded that the proposed control strategy is correct for above compound fault, it can achieve rapid recovery after faults, effectively improve fault tolerance of the system, develop the stability and reliability of the system.

  13. Grid Integration of Offshore Wind Farms via VSC-HVDC – Dynamic Stability Study

    DEFF Research Database (Denmark)

    Liu, Hongzhi

    -HVDC transmission are addressed. The main objectives have been to study the dynamic interactions between offshore wind farms and interconnected power systems, pinpoint the impact on the electrical grid while integrating large-scale offshore wind farms via VSC-HVDC link and propose potential solutions to improve......, may not be able to respond to the onshore grid frequency excursion in time. Consequently, the stability and security of power system will be put at risk, especially for those with high wind penetration. A coordinated frequency control scheme is developed not only to reduce the responding latency...... fluctuation mitigation. A new converter rating evaluation approach as well as a new power management strategy is proposed to enable the BESS to enhance the system frequency response on the basis of wind power fluctuation mitigation....

  14. Ebola Virus Shedding and Transmission: Review of Current Evidence.

    Science.gov (United States)

    Vetter, Pauline; Fischer, William A; Schibler, Manuel; Jacobs, Michael; Bausch, Daniel G; Kaiser, Laurent

    2016-10-15

     The magnitude of the 2013-2016 Ebola virus disease outbreak in West Africa was unprecedented, with >28 500 reported cases and >11 000 deaths. Understanding the key elements of Ebola virus transmission is necessary to implement adequate infection prevention and control measures to protect healthcare workers and halt transmission in the community.  We performed an extensive PubMed literature review encompassing the period from discovery of Ebola virus, in 1976, until 1 June 2016 to evaluate the evidence on modes of Ebola virus shedding and transmission.  Ebola virus has been isolated by cell culture from blood, saliva, urine, aqueous humor, semen, and breast milk from infected or convalescent patients. Ebola virus RNA has been noted in the following body fluids days or months after onset of illness: saliva (22 days), conjunctiva/tears (28 days), stool (29 days), vaginal fluid (33 days), sweat (44 days), urine (64 days), amniotic fluid (38 days), aqueous humor (101 days), cerebrospinal fluid (9 months), breast milk (16 months [preliminary data]), and semen (18 months). Nevertheless, the only documented cases of secondary transmission from recovered patients have been through sexual transmission. We did not find strong evidence supporting respiratory or fomite-associated transmission. © The Author 2016. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail journals.permissions@oup.com.

  15. Current status of transmissible spongiform encephalopathies in ruminants

    Directory of Open Access Journals (Sweden)

    Penders J.

    2004-01-01

    Full Text Available Transmissible spongiform encephalopathies (TSE encompass subacute neurological degenerative diseases for which the prototypes are scrapie in sheep and some forms of Creutzfeldt-Jakob disease in man. The emergence of a new form of TSE in cattle in United Kingdom (UK since 1986, namely bovine spongiform encephalopathy (BSE, sharply increased the interest for these diseases, especially because of the epidemic nature of BSE in UK, its subsequent spread in continental Europe and the later discovery of its zoonotic character. The number of measures of veterinary public health taken to control the disease and to prevent its spread to animals and human beings increased in time and culminated by the total feed ban. Indeed, since the beginning of 2001, feed containing proteins of animal origin is prohibited for the feeding of production animals, including ruminants and monogastric species. The effect of this total ban of mammalian meat and bone meal needs to be evaluated. The incidence of BSE has a trend to decrease in UK and in most of the other European member states. However, as BSE is a rare event distributed in a large bovine population, it is difficult to state unambiguously whether this trend is significant. Furthermore, the evaluation of this measure will be only effective at least five years after its introduction, since this period is the mean incubation time of BSE. The main concern is currently the eradication of BSE in the infected countries. Additionally, the control of scrapie is also carried out due to the possible contamination of sheep with the BSE agent. These actions must take into account several new facts: the recent discovery of BSE cases in countries with a low geographical BSE risk level as Japan, Canada and the United States of America (USA; the growing incidence of chronic wasting disease, a spongiform encephalopathy observed in deer in USA; the characterization of a new pattern of bovine amyloidotic spongiform encephalopathy in

  16. Design and analysis of HVDC switch gear station for meshed HVDC grid

    OpenAIRE

    Serrano Jiménez, Patricia

    2013-01-01

    It is of fundamental interest to avoid faults in a DC grid due to the severely of these events. However, the faults are unavoidable, so in a fault case is necessary to act fast. The protection in a DC grid comprises a key component, the HVDC breaker. For this reason in this thesis, a simulation is programmed in order to be able to study the HVDC breaker operation, distinguishing between normal and fault operation. Matlab is the program used in this work, and an initial simulation is tested...

  17. Vertical transmission of hepatitis C virus: Current knowledge and perspectives

    Institute of Scientific and Technical Information of China (English)

    Chun-Yan; Yeung; Hung-Chang; Lee; Wai-Tao; Chan; Chun-Bin; Jiang; Szu-Wen; Chang; Chih-Kuang; Chuang

    2014-01-01

    Hepatitis C virus(HCV) infection is a major global health issue.Infection by the HCV can cause acute and chronic liver diseases and may lead to cirrhosis,hepatocellular carcinoma or liver failure.The World Health Organization estimates that approximately 3% of the world population have been infected with HCVand the worldwide prevalence is between 1% and 8% in pregnant women and between 0.05% and 5% in children.Following the introduction of blood product screening,vertical transmission becomes the leading cause of childhood HCV infection.The prevalence of pediatric HCV infection varies from 0.05% to 0.36% in developed countries and between 1.8% and 5% in the developing world.All children born to women with antiHCV antibodies should be checked for HCV infection.Though universal screening is controversial,selective antenatal HCV screening on high-risk populations is highly recommended and should be tested probably.Multiple risk factors were shown to increase the possibility of HCV vertical transmission,including coinfections with human immunodeficiency virus,intravenous drug use and elevated maternal HCV viral load,while breastfeeding and HCV genotypes have been studied to have little impact.At present,no clinical intervention has been clearly studied and proved to reduce the HCV vertical transmission risk.Cesarean section should not be recommended as a procedure to prevent vertical transmission,however,breastfeeding is generally not forbidden.The high prevalence of global HCV infection necessitates renewed efforts in primary prevention,including vaccine development,as well as new approaches to reduce the burden of chronic liver disease.Future researches should focus on the interruption of vertical transmission,developments of HCV vaccine and directacting antivirals in infancy and early childhood.

  18. Definition and Classification of Terms for HVDC Networks

    DEFF Research Database (Denmark)

    Vrana, Til Kristian; Bell, Keith; Sørensen, Poul Ejnar

    2015-01-01

    A systematic terminology for the field of HVDC networks has been developed, closing the gap between the well-established terminologies from AC power systems and HVDC technology. The most relevant items, topologies and concepts have been given clear and unique defined names, and these have been cl...

  19. Simulation of HVDC light system based on MATLAB%基于 MATLAB 的轻型直流输电系统的仿真

    Institute of Scientific and Technical Information of China (English)

    冯媛硕; 宋吉江; 沙宏哲

    2015-01-01

    轻型直流输电(HVDC Light)是一种新型的输电技术,以电压源换流器(VSC)为核心,控制上采用脉宽调制技术( PWM)以达到高可控性直流输电的目的。文章首先分析了轻型直流输电系统的基本结构和原理,然后利用MATLAB仿真软件建立一个三电平轻型直流输电系统的仿真模型,最后对仿真结果进行分析,仿真结果表明建立的轻型直流输电系统具有较好的稳定精度和响应速度。文章为将来研究轻型直流输电系统的物理模型奠定了一定的理论基础。%HVDC Light is a new technology of DC transmission, in which VSC ( Voltage Source Converter) acted as the core.Control system adopts the PWM technique to reach the high controllable DC transmission.Firstly, the basic structure and fundamental principle of the HVDC Light system were introduced briefly.Then, a simulation model for the typical three-level HVDC Light power transmission system was built on MATLAB.The simulation results were ana-lyzed at last.The simulation results show that the HVDC Light system has good stabilization accuracy and response speed.This study provides a theoretical basis for further research on the physical model of the HVDC Light system.

  20. The Identification of Internal and External Faults for±800kV UHVDC Transmission Line Using Wavelet based Multi-Resolution Analysis

    Directory of Open Access Journals (Sweden)

    Shu Hongchun

    2011-05-01

    Full Text Available There is a smoothing reactor and DC filter between the inverter and the direct current line to form a boundary in the HVDC transmission system. Since this boundary presents the stop-band characteristic to the high frequency transient voltage signals, the high-frequency transient voltage signal caused by external faults through boundary will be attenuated and the signals caused by internal faults will be unchanged. The wavelet analysis can be used as a tool to extract the feature of the fault to classify the internal fault and the external fault in HVDC transmission system. This paper explores the new method of wavelet based Multi-Resolution Analysis for signal decomposition to classify the difference types fault.

  1. Comparison of Return Stroke Current Profiles for Transmission-Line-Type and Traveling-Current-Source-Type Models

    Directory of Open Access Journals (Sweden)

    J.O. Adepitan

    2012-05-01

    Full Text Available The study is aimed at determining the dependence of the current along a channel on the model used, assuming the same base current. We compared three transmission-line-type models, namely: Transmission Line (TL, Modified Transmission Line with Linear decay, Modified Transmission Line with Exponential decay and two traveling-current-source-type models: Bruce-Golde (BG and Traveling Current Source (TCS models. The current profiles along the channel at different heights predicted by these models are presented and discussed. Comparison is based on the assumption that all the models have the same base current. It was found that at low heights and within a time window frame of 15 :s, the currents of the transmission-line-type models predict a zero value at one time or the other with a maximum turning point following some 1:s after. A linear relationship is predicted between the current peak and the channel height. A discontinuity of current peak was observed at high heights. No zero value of current was recorded in case of TCS both at low and high channel heights.

  2. Limiting electric fields of HVDC overhead power lines.

    Science.gov (United States)

    Leitgeb, N

    2014-05-01

    As a consequence of the increased use of renewable energy and the now long distances between energy generation and consumption, in Europe, electric power transfer by high-voltage (HV) direct current (DC) overhead power lines gains increasing importance. Thousands of kilometers of them are going to be built within the next years. However, existing guidelines and regulations do not yet contain recommendations to limit static electric fields, which are one of the most important criteria for HVDC overhead power lines in terms of tower design, span width and ground clearance. Based on theoretical and experimental data, in this article, static electric fields associated with adverse health effects are analysed and various criteria are derived for limiting static electric field strengths.

  3. Microtubule as a Transmission Line for Ionic Currents

    Institute of Scientific and Technical Information of China (English)

    ILI(C) D.I.; SATARI(C) M.V.; RALEVI(C) N.

    2009-01-01

    We establish a new model for ionic waves along microtubules based on polyelectrolyte features of cylindrical biopolymers. The nonlinear transmission line described by a nonlinear differential equation is obtained with stable kink solution pertinent to the shape of the front of accompanying potential. The localized ionic wave could be used to explain the behavior of microtubules as biomolecular transistors capable of amplifying electrical information in neurons.

  4. African Horse Sickness Virus: History, Transmission, and Current Status.

    Science.gov (United States)

    Carpenter, Simon; Mellor, Philip S; Fall, Assane G; Garros, Claire; Venter, Gert J

    2017-01-31

    African horse sickness virus (AHSV) is a lethal arbovirus of equids that is transmitted between hosts primarily by biting midges of the genus Culicoides (Diptera: Ceratopogonidae). AHSV affects draft, thoroughbred, and companion horses and donkeys in Africa, Asia, and Europe. In this review, we examine the impact of AHSV critically and discuss entomological studies that have been conducted to improve understanding of its epidemiology and control. The transmission of AHSV remains a major research focus and we critically review studies that have implicated both Culicoides and other blood-feeding arthropods in this process. We explore AHSV both as an epidemic pathogen and within its endemic range as a barrier to development, an area of interest that has been underrepresented in studies of the virus to date. By discussing AHSV transmission in the African republics of South Africa and Senegal, we provide a more balanced view of the virus as a threat to equids in a diverse range of settings, thus leading to a discussion of key areas in which our knowledge of transmission could be improved. The use of entomological data to detect, predict and control AHSV is also examined, including reference to existing studies carried out during unprecedented outbreaks of bluetongue virus in Europe, an arbovirus of wild and domestic ruminants also transmitted by Culicoides.

  5. Highly efficient solutions for smart and bulk power transmission of 'green energy'

    Energy Technology Data Exchange (ETDEWEB)

    Breuer, Wilfried; Retzmann, Dietmar; Uecker, Karl

    2010-09-15

    Environmental constraints, loss minimization and CO2 reduction will play an increasingly more important role in future. Security and sustainability of power supply as well as economic efficiency needs application of advanced technologies. Innovative solutions with HVDC (High Voltage Direct Current) and FACTS (Flexible AC Transmission Systems) have the potential to cope with these challenges. They provide the features which are necessary to avoid technical problems in power systems, they increase the transmission capacity and system stability very efficiently and help prevent cascading outages. Furthermore, they are essential for Grid Access of Renewable Energy Sources such as Hydro, Wind and Solar-Energy.

  6. Persistent current and transmission probability in the Aharonov-Bohm ring with an embedded quantum dot

    Energy Technology Data Exchange (ETDEWEB)

    Wu Suzhi; Li Ning [National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093 (China); Jin Guojun [National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093 (China)], E-mail: gjin@nju.edu.cn; Ma Yuqiang [National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093 (China)

    2008-03-24

    Persistent current and transmission probability in the Aharonov-Bohm (AB) ring with an embedded quantum dot (QD) are studied using the technique of the scattering matrix. For the first time, we find that the persistent current can arise in the absence of magnetic flux in the ring with an embedded QD. The persistent current and the transmission probability are sensitive to the lead-ring coupling and the short-range potential barrier. It is shown that increasing the lead-ring coupling or the short-range potential barrier causes the suppression of the persistent current and the increasing resonance width of the transmission probability. The effect of the potential barrier on the number of the transmission peaks is also investigated. The dependence of the persistent current and the transmission probability on the magnetic flux exhibits a periodic property with period of the flux quantum.

  7. Coordinated system services from offshore wind power plants connected through HVDC networks

    DEFF Research Database (Denmark)

    Zeni, L.; Glasdam, Jakob Bærholm; Hesselbæk, B.

    2014-01-01

    This paper presents an overview of power system services in networks involving multiple onshore power systems, a voltage sourced converter (VSC) based high voltage direct current (HVDC) offshore network and an offshore wind power plant (OWPP). A comprehensive list of services regarding onshore...... control and communication delays of OWPPs, and their influence on the successful delivery of the targeted services. Furthermore, it is shown that as an HVDC network increases in size from the point-to-point, the handling of onshore short circuits calls for the proper combination of DC chopper(s) and fast...... as well as offshore network operation – both AC and DC – will be discussed from a state of the art perspective. Among them, the most interesting have been selected and will be treated in more detail and the main contribution of this paper will be to shed light on the most relevant aspects related...

  8. Investigation of Hybrid Bipolar HVDC System Performances%混合双极高压直流输电系统的特性研究

    Institute of Scientific and Technical Information of China (English)

    郭春义; 赵成勇; Allan Montanari; Aniruddha M. Gole; 肖湘宁

    2012-01-01

    为了充分发挥电网换相换流器高压直流输电系统 (line commutated converter based high voltage direct current,LCC—HVDC)和电压源换流器高压直流输电系统(voltagesourceconverterbasedHVDC,VSC.HVDC)的优势,针对~种新型的混合双极高压直流输电系统(hybridbipolarbasedhighvoltagedirectcurrent,HB—HVDC)进行了研究,该系统的正极是传统的12脉动LCC.HVDC系统,而负极是VSC—HVDC系统。建立了由LCC正极和VSC负极组成的混合双极高压直流输电系统的模型,推导了其在稳态时的数学模型,并设计了正负极之间的协调控制策略。在PSCAD/EMTDC环境下对HB—HVDC系统的稳态和暂态运行特性进行了研究分析。最后对HB—HVDC系统和闭锁负极VSC—HVDC后LCC—HVDC系统的运行特性进行了对比研究。结果表明:HB-HVDC系统可以更好地调节交流母线电压,减少LCC极换相失败的可能性,并且具有快速的故障恢复能力;同时也证明所设计的协调控制策略可以有效地改善HB—HVDC系统的稳态和动态特性。%A new hybrid bipolar high voltage direct current system (HB-HVDC) was investigated to synthetically utilize the advantages of line commutated converter based HVDC (LCC-HVDC) and voltage source converter based HVDC (VSC-HVDC). The positive pole was a conventional 12-pulse LCC-HVDC system and the negative pole was a VSC-HVDC system. The model of HB-HVDC was developed, and its steady-state mathematical model was deduced. Then the coordinated control strategy between positive pole LCC-HVDC and negative pole VSC-HVDC was designed. The operation performances of HB-HVDC system in steady and transient state were studied. Finally, the performances of the HB-HVDC system were compared with an identical LCC- HVDC with VSC-HVDC blocked. The results show that HB- HVDC system has a better regulation for AC busbar voltage, makes the LCC-HVDC less susceptible to commutation

  9. 模块化多电平直流输电联网风电场时的低电压穿越技术%Low Voltage Ride-Through Technology for Wind Farms Connected to Power Grid via MMC-Based HVDC Transmission

    Institute of Scientific and Technical Information of China (English)

    赵静; 赵成勇; 孙一莹; 张建坡; 敬华兵

    2013-01-01

    It is a better scheme for grid-connection of large-capacity long-distance offshore wind farms via HVDC flexible.Aiming at the problem of applying modular multilevel converter-based HVDC (MMC-HVDC) to grid-connection of large-scale offshore wind farms,corresponding steady-state control strategy for MMC-HVDC is analyzed and researched,and the feasibility of such a scheme is verified by simulation.To ensure that when unsymmetrical fault occurred at the grid-connection point,where the grid-connection system is connected to AC power grid,the not-off-grid operation of wind farm can be sustained,a controller for MMC-HVDC during unsymmetrical fault is designed to isolate the wind farm from the fault and transmit power to AC grid as possible to improve the low voltage ride-through capability of the wind farm.The feasibility and effectiveness of the proposed method are verified by the simulation carried out in PSCAD/EMTDC.%柔性直流输电并网方式对于大容量远距离海上风电场是一种较好的并网方案.针对模块化多电平直流输电(modular multilevel converter-HVDC,MMC-HVDC)应用于大规模风电场联网问题,分析研究了相应的MMC-HVDC稳态控制策略,仿真验证了其可行性.为保证当联网系统与交流系统的并网点发生不对称故障时风电场可以不脱网持续运行,设计了MMC-HVDC不对称故障期间的控制器,以将风电场与故障隔离并尽可能将功率传送至交流系统中,提高了风电场的低电压穿越能力,并在PSCAD/EMTDC中搭建的仿真模型上验证了此方法的可行性及有效性.

  10. An Optoelectronic High-voltage Probe for Measuring Impulse Voltage Distribution of HVDC Converter Valve

    Institute of Scientific and Technical Information of China (English)

    方志; 邱毓昌

    2007-01-01

    A high-voltage optoelectronic probe is developed for measuring impulse voltage distribution along thyristor units in the HVDC converter valve. The dimension of the resistive voltage divider is optimized by means of numerical compttation of electric field. A pulse frequency modulation (PFM) mode is adopted for the data transmission link because of its immunity to high-intensity electromagnetic interference. Experimental results indicate that the linearity deviation for the whole measuring system is within ± 0.15 %, and therefore it can meet requirements specified by IEC60700-1.

  11. The first three 800 MW wind park grid connection projects with XLPE HVDC cables

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Dongping; Lebioda, Thomas Jan; Koochack-Zadeh, Masoumeh; Jung, Jochen [TenneT Offshore GmbH, Bayreuth (Germany). Asset Management Offshore

    2011-07-01

    This paper presents the first three wind grid connection projects in class of 800 MW by TenneT Offshore in the German North Sea. According to the requirements of transmission capacity, distance and other technical and environmental constraints, the HVDC-VSC-technology and XLPE-cable are chosen to fulfill the task of grid connection. To time of this publication, these three projects are in project implementation phase and under construction. In this paper the detailed information about those three projects will be introduced and the first experiences and challenges will be reviewed from the stand point of the coastal TSO. (orig.)

  12. Transients in VSC-HVDC connected offshore wind power plant

    DEFF Research Database (Denmark)

    El-Khatib, Walid Ziad; Schwartzberg, D.; Arana Aristi, I.;

    2015-01-01

    The focus of this paper is transient phenomena in VSC-HVDC connected offshore wind power plants (WPPs). With the help of a case study modelled in PSCAD simulation software, energisation events are analysed in the time domain. A comparison with more well-known results obtained at energisation of AC...... connected WPPs indicates that significant differences arise as the energy involved in the switching event increases, due to the presence of the HVDC converter control. The influence of the offshore HVDC converter control gain in the most critical cases is assessed empirically and explained qualitatively....

  13. 多回直流输电线路的离子流场计算%Ion Flow Field Calculation of Multi-circuit DC Transmission Lines

    Institute of Scientific and Technical Information of China (English)

    李伟; 张波; 何金良

    2008-01-01

    An upwind finite element (FE) based algorithm to calculate the ion flow field in the vicinity of multi-circuit DC transmission lines is described. The initial value estimation and boundary condition are optimized, so details of the transmission lines such as bundle conductors and ground wires can be taken into account in the simulation model. Comparison between measured and computed ground level total electrical field and ion current density shows satisfactory agreement. The ion flow field of a ±500 kV HVDC Project with bipolar lines on the same tower is simulated. The total electrical field and ion current density on ground level are compared among different line arrangements.

  14. MIDOT: A novel probe for monitoring high-current flat transmission lines

    Science.gov (United States)

    Omar, K.; Novac, B. M.; Graneau, N.; Senior, P.; Smith, I. R.; Sinclair, M.

    2016-12-01

    A novel inductive probe, termed MIDOT, was developed for monitoring high-current flat transmission lines. While being inexpensive the probe does not require calibration, is resistant to both shock waves and temperature variations, and it is easy to manufacture and mount. It generates strong output signals that are relatively easy to interpret and has a detection region limited to a pre-defined part of the transmission line. The theoretical background related to the MIDOT probes, together with their practical implementation in both preliminary experimentation and high-current tests, is also presented in the paper. The novel probe can be used to benchmark existing 2D numerical codes used in calculating the current distribution inside the conductors of a transmission line but can also easily detect an early movement of a transmission line component. The probe can also find other applications, such as locating the position of a pulsed current flowing through a thin wire.

  15. Power-flow control and stability enhancement of four parallel-operated offshore wind farms using a line-commutated HVDC link

    DEFF Research Database (Denmark)

    Wang, Li; Wang, Kuo-Hua; Lee, Wei-Jen

    2010-01-01

    This paper presents an effective control scheme using a line-commutated high-voltage direct-current (HVDC) link with a designed rectifier current regulator (RCR) to simultaneously perform both power-fluctuation mitigation and damping improvement of four parallel-operated 80-MW offshore wind farms...

  16. AC Loss of Ripple Current in Superconducting DC Power Transmission Cable

    Science.gov (United States)

    Yoshitomi, K.; Otabe, E. S.; Vyatkin, V. S.; Kiuchi, M.; Matsushita, T.; Hamabe, M.; Yamaguchi, S.; Inada, R.

    As a method of largely reducing the transmission loss in the electric power grid, superconducting direct current (DC) power transmission cable has been investigated. Using superconducting DC power transmission cables, large amounts of current and energy can be transferred compared to conventional copper cables. In this case, an alternating current (AC) is converted to DC and superposed AC which is known as ripple current, and the energy loss by the ripple current is generated. Therefore it is desired to estimate the energy loss density for the case of DC current and superposed AC current for a design of DC transmission cable system. In this study, the hysteresis loss for DC current of 2 kA rectified from 60 Hz alternating current is calculated using the Bean model, and coupling loss was also estimated. The diameter of the cable was 40 mm. The ripple currents generated by multi-pulse rectifiers, 6-pulse, 12-pulse, and 24-pulse were considered. It is found that the total AC loss including the hysteresis loss and the coupling loss is considerably smaller than the supposed heat loss of 0.5 W/m which is obtained with a newly developed cable.

  17. The HVDC control and protection simulation platform based on PSCAD/EMTDC and its application in HVDC projects%基于PSCAD/EMTDC的直流控制保护系统仿真平台及其在直流工程中的应用

    Institute of Scientific and Technical Information of China (English)

    张民; 贺仁睦; 孙哲; 王柏恒

    2013-01-01

      基于目前普遍采用的电磁暂态仿真工具PSCAD/EMTDC,根据实际工程软件进行了直流控制保护系统仿真平台的二次开发。分析了直流控制保护工程软件在工控机中的分时处理、中断计算过程及其在PSCAD/EMTDC中的等效实现方法,利用该仿真平台进行了灵宝扩建背靠背直流工程的控制系统建模。将基于本平台搭建的电磁暂态模型与实际工程系统调试时的电流阶跃响应结果进行了对比,证明该平台与工程实际控制保护系统功能等效。基于该平台进行直流工程控制系统仿真的结果可信,对于广泛开展跨区直流输电系统的电磁暂态仿真研究具有工程实际指导意义。%This paper describes the secondary development of HVDC control and protection system simulation platform based on the actual engineering software and the currently widely used electric magnetic transient simulation tools PSCAD/EMTDC. This paper analyzes the time interrupt and Task/Proc scheduler mechanism of actual control and protection application software which operates on industrial control computer, as well as its equivalent simulation method in PSCAD/EMTDC. The simulation platform is used to build the control system model of Lingbao II BTB HVDC project. Comparing the new electric magnetic transient model with DC current step response result of simulation and on-site commissioning, it is found that the simulation platform has an equivalent function of the actual control and protection system. The simulation results based on the new designed simulation platform are credible, which has guiding significance for extensively carrying out the electric magnetic transient simulation of inter-district HVDC transmission system.

  18. Vibration and Audible Noise of Filter Capacitors in HVDC Converter Stations%Vibration and Audible Noise of Filter Capacitors in HVDC Converter Stations

    Institute of Scientific and Technical Information of China (English)

    ZHU Ling-yu; JI Sheng-chang

    2011-01-01

    The filter capacitor stack is one of the main acoustic noise sources in high-voltage DC (HVDC) converter stations. As HVDC systems are built more and more recently, it is significant to research the audible noise of filter capacitors. In this paper, the current situation of research on vibration and audible noise of filter capacitors in HVDC converter stations, which is departed into three parts--generation mechanism, prediction methods, and reduction measures, is presented and the research achievements are discussed. Scholars have built the model that the alternating electric force caused by the voltage conduces to the vibration, which propagates to the enclosure and radiates audible noise. As a result, the parts contributing most to the generation of audible noise are the top and the bottom of capacitors. In the noise level prediction respect, several methods have been prospected including impact hammer, sweep frequency, impact current, monopole and Kirchhoff formula method, which are suitable for single capacitors or capacitors stacks individually. However, the sweep frequency method is restricted by experiment condition, and the impact current method needs further research and verified. On the other hand, CIGRE WG14.26 provides three sound reduction measures, but all of them are not so practicable, while MPP absorber and compressible space absorber prospected by Dr. Wu Peng are proved to be effective. The sound barriers are also considered by scholars, and the acoustic directivity performance of capacitors is also researched. Besides, the developing direction of each research field is prospected in corresponding part.

  19. Development of Broadband Voltage Electro-optical Measurement System for Converter Valve Components Used in HVDC Power Transmission%HVDC换流阀组件宽频带电压光电测量系统的研制

    Institute of Scientific and Technical Information of China (English)

    薛阳; 李跃; 程养春; 张春雨; 李光茂; 宗文志

    2011-01-01

    To verify the voltage sharing effect of converter valve components, an electro-optical measurement system to measure voltage distribution among converter valve component is developed. This measurement system consists of probes,lighting-emitting devices, optical fiber transmission system and photoelectric conversion devices, and possesses the property of small-size and portability. The bandwidth tests and impulse voltage tests for the designed electro-optical measurement system are performed, and the measured bandwidth is within the range from DC to 7 MHz. Test results show that the designed measurement system can effectively avoid the interference from electromagnetic environment and can meet the demand of measuring voltage distribution among converter valve components.%研制了用于测量换流阀组件电压分布的光电测量系统,以检验其均压效果.该系统主要由探头、光发射装置、光纤传输系统、光电转换装置组成,具有小尺寸、便携等特点.对所设计的光电测量系统进行了频带、冲击电压测试,其带宽为直流至7 MHz.试验结果表明,所设计的测量系统可以有效避免电磁环境干扰,能够满足测量换流阀组件电压分布的需要.

  20. Current Reflection and Transmission at Conformal Defects: Applying BCFT to Transport Process

    CERN Document Server

    Kimura, Taro

    2014-01-01

    We study reflection/transmission process at conformal defects by introducing new transport coefficients for conserved currents. These coefficients are defined by using BCFT techniques thanks to the folding trick, which turns the conformal defect into the boundary. With this definition, exact computations are demonstrated to describe reflection/transmission process for a class of conformal defects. We also compute the boundary entropy based on the boundary state.

  1. A Review of Muti-Terminal VSC-HVDC System in Large Wind Farms%大型风电基地多端 VSC-HVDC系统综述

    Institute of Scientific and Technical Information of China (English)

    吴瀚俊; 刘海涛

    2014-01-01

    In recent years,the upgrowth of fully-controlled devices and pulse width modulation device PWM technology,has paved the way for the appearance and progression of VSC-HVDC technology.Multi-terminal VSC-HVDC technology can be applied to address such problems as island supply,distributed generation system connecting to large power grids,etc.This paper elucidates the principle of VSC-HVDC,and compares AC transmission and normal HVDC,aimed at highlighting the advantages of VSC-HVDC.The working mode of convertors,a key part of VSC-HVDC,is also briefly introduced.More importantly,this paper demonstrates topology and coordination control strategy of multi-terminal VSC-HVDC system in large-scale offshore wind farms,and predicts its future development trend.%随着近年来全控型器件的出现和发展以及脉宽调制( PWM)技术的日臻成熟,为VSC-HVDC技术的产生和发展创造了条件,而多端VSC-HVDC技术可以很好地解决孤岛供电、分布式发电系统接入大电网等问题。文章就VSC-HVDC原理进行阐述,通过对比交流输电和常规HVDC来突出VSC-HVDC的优点,并简单介绍了VSC-HVDC的关键部分也就是变流器的运行模式。文章重点论述大型风电基地多端VSC-HVDC系统的拓扑结构和协调控制策略,并对其未来发展趋势作出预测。

  2. VSC-HVDC系统启动控制%Startup Procedures for the VSC-HVDC System

    Institute of Scientific and Technical Information of China (English)

    张静; 徐政; 陈海荣

    2009-01-01

    In order to reduce the undesired impacts and damages on the VSC-HVDC system and the connected AC system during the startup and re-startup procedures, appropriate startup control strategy should be dedicatedly designed. Charging the DC capacitor voltage to the preset value quickly is the fundamental of the subsequent control strategy. In this paper, a two-stage self startup procedure is proposed for VSC-HVDC system consisting of two-level and diode-clamped three-level converters. During the first stage, the resistors are inserted to limit the current during the charging. If the DC voltage can not reach the preset value after predetermined time, the startup procedure switches to the second stage and the capacitors will be further charged with a DC voltage controller. The startup procedure completes till the DC link voltage reaches the preset value and then the converters are ready to change from the startup mode to the normal operating mode. In addition, a new control strategy is proposed for the startup of the passive network and the AC system suffered from black out. With the proposed control strategy, the inrush currents during the energization of the transformers and the overvoltage during the closure of the long overhead transmission lines can be suppressed. Simulation results verify the feasibility of the proposed startup procedures.%合适的启动方式对减缓VSC-HVDC系统启动及重新启动时对自身和电网的冲击非常重要.如何把直流电容器电压快速提升到设定值,是后续控制策略正确工作的基础.针对目前应用较广泛的两电平和二极管钳位型三电平换流器拓扑结构,提出了一种简单、适用于VSC-HVDC系统的两阶段自励启动方法.在启动第一阶段,串接限流电阻器对直流侧电路充电;若在设定的时间内电容器电压不能达到设定值,启动转入第二阶段,即换流站在直流电压控制器的作用下对电容器继续充电,直至达到预设值,从而为换

  3. Inertial Response of an Offshore Wind Power Plant with HVDC-VSC

    Energy Technology Data Exchange (ETDEWEB)

    Preciado, V.; Gevorgian, Vahan; Muljadi, Eduard; Madrigal, M.

    2017-01-05

    This paper analyzes the inertial response of an offshore wind power plant (WPP) to provide ancillary services to the power system grid. The WPP is connected to a high-voltage direct-current voltage source converter HVDC-VSC to deliver the power to the onshore substation. The wind turbine generator (WTG) used is a doubly-fed induction generator (Type 3 WTG). In this paper we analyze a control method for the WTGs in an offshore WPP to support the grid and contribute ancillary services to the power system network. Detailed time domain simulations will be conducted to show the transient behavior of the inertial response of an offshore WPP.

  4. Improvement of Power System Stability using Artificial Neural Network based HVDC Controls

    Directory of Open Access Journals (Sweden)

    Nagu Bhookya

    2013-06-01

    Full Text Available In this paper, investigation is carried out for the improvement of power system stability by utilizing auxiliary controls for controlling HVDC power flow. The current controller model and the line dynamics are considered in the stability analysis. Transient stability analysis is done on a multi-machine system, where, a neural network controller is developed to improve the stability of the power system and to improve the response time of the controller to the changing conditions in power system. The results show the application of the neural network controller in AC-DC power systems.

  5. 型式试验对挤塑绝缘高压直流电缆老化状态的影响研究%Influence of Type Test on Ageing Status of Extruded Cross-linked Polyethylene (XLPE) High Voltage Direct Current (HVDC) Cables

    Institute of Scientific and Technical Information of China (English)

    李淑琦; 朱永华; 罗兵; 廖一凡; 吴建东; 尹毅

    2015-01-01

    The influence of type test on cable insulation was analyzed by testing the space charge, iso-thermal relaxation current (IRC), and thermal properties of 200 kV home-made extruded XLPE HVDC cables. The degassed samples from the central section of main insulation had distinct heteropolar space charge distribution on the surface before and after type test, while the accumulation of space charge changed little, and the status factor, enthalpy, and crosslinking degree had little change also, which indicated that the influence of type test on the ageing degree of central insulation of cables was small. After degassing treatment, the accumulation of heteropolar space charge and the average charge density reduced significantly, this indicated that the space charge behavior was influenced by crosslinking byprod-ucts. The test results of IRC and DSC show good relevance and can effectively reflect the change of age-ing status, which means that they are suitable to evaluate the insulation status of extruded XLPE HVDC cables.%通过对国内自行研制的200 kV挤塑绝缘交联聚乙烯电缆的空间电荷、松弛电流和热性能进行测试,分析了型式试验对电缆绝缘的影响。型式试验前后,主绝缘中部切片试样在表面区域均存在明显的异极性空间电荷分布,且电荷积累量变化不大,状态因子、熔融热焓、结晶热焓和交联度变化亦不明显,表明型式试验对电缆中部绝缘的老化程度影响较小。切片脱气处理后,试样表面区域的异极性空间电荷积累和短路时空间电荷平均单位体积密度显著降低,表明空间电荷行为受制造过程中残留的交联副产物影响很大。空间电荷、等温松弛电流和差示扫描量热的测试结果的关联性较好,均能有效反映老化状态的变化,可用于挤塑绝缘直流电缆的绝缘状态评估。

  6. Flip-Flops for accurate multiphase clocking: transmission gate versus current mode logic

    NARCIS (Netherlands)

    Dutta, R.; Klumperink, Eric A.M.; Gao, X.; Ru, Z.; van der Zee, Ronan A.R.; Nauta, Bram

    2013-01-01

    Dynamic transmission gate (DTG) flip-flops (FFs) (DTG-FFs) and current mode logic (CML) FFs (CML-FFs) are compared targeting power efficient multiphase clock generation with low phase error. The effect of component mismatches on multiphase clock timing inaccuracies is modeled and compared, using the

  7. Current status and future directions for in situ transmission electron microscopy

    DEFF Research Database (Denmark)

    Taheri, Mitra L.; Stach, Eric A.; Arslan, Ilke

    2016-01-01

    This review article discusses the current and future possibilities for the application of in situ transmission electron microscopy to reveal synthesis pathways and functional mechanisms in complex and nanoscale materials. The findings of a group of scientists, representing academia, government labs...

  8. Flip-Flops for accurate multiphase clocking: transmission gate versus current mode logic

    NARCIS (Netherlands)

    Dutta, R.; Klumperink, E.A.M.; Gao, X.; Ru, Z.; Zee, van der R.A.R.; Nauta, B.

    2013-01-01

    Dynamic transmission gate (DTG) flip-flops (FFs) (DTG-FFs) and current mode logic (CML) FFs (CML-FFs) are compared targeting power efficient multiphase clock generation with low phase error. The effect of component mismatches on multiphase clock timing inaccuracies is modeled and compared, using the

  9. A Comparative Parametric Analysis of the Ground Fault Current Distribution on Overhead Transmission Lines

    OpenAIRE

    VINTAN, M.

    2016-01-01

    The ground fault current distribution in an effectively grounded power network is affected by various factors, such as: tower footing impedances, spans lengths, configuration and parameters of overhead ground wires and power conductors, soil resistivity etc. In this paper, we comparatively analyze, using different models, the ground fault current distribution in a single circuit transmission line with one ground wire. A parametric comparative analysis was done in order to stud...

  10. Decreasing the commutation failure frequency in HVDC transmission systems

    DEFF Research Database (Denmark)

    Hansen (retired June, 2000), Arne; Havemann (retired June, 2000), Henrik

    2000-01-01

    with equidistant firing pulses to a strategy that takes into consideration the potentially dangerous voltage changes on the supply lines, If the supply voltages are monitored continuously, it is possible to calculate the necessity of advancing the firing pulses to avoid commutation failures. In the paper......In this paper we show how a fairly large proportion of those commutation failures that are due to single-phased short circuits to earth can be avoided. In a control circuit based on a digital signal processor (DSP) it is possible, with instantaneous results, to switch from a normal control strategy...

  11. Rats avoid exposure to HVdc electric fields: a dose response study.

    Science.gov (United States)

    Creim, J A; Lovely, R H; Weigel, R J; Forsythe, W C; Anderson, L E

    1993-01-01

    Rats, given the choice, avoid exposure to alternating current (ac) 60-Hz electric fields at intensities > or = 75 kV/m. This study investigated the generality of this behavior by studying the response of rats when exposed to high voltage direct current (HVdc) electric fields. Three hundred eighty male Long Evans rats were studied in 9 experiments with 40 rats per experiment and in one experiment with 20 rats to determine 1) if rats avoid exposure to HVdc electric fields of varying field strengths, and 2) if avoidance did occur, what role, if any, the concentration of air ions would have on the avoidance behavior. In all experiments a three-compartment glass shuttlebox was used; either the left or right compartment could be exposed to a combination of HVdc electric fields and air ions while the other compartment remained sham-exposed. The third, center compartment was a transition zone between exposure and sham-exposure. In each experiment, the rats were individually assessed in 1-h sessions where half of the rats (n = 20) had the choice to locomote between the two sides being exposed or sham-exposed, while the other half of the rats (n = 20) were sham-exposed regardless of their location, except in one experiment where there was no sham-exposed group. The exposure levels for the first six experiments were 80, 55, 42.5, 30, -36, and -55 kV/m, respectively. The air ion concentration was constant at 1.4 x 10(6) ions/cc for the four positive exposure levels and -1.4 x 10(6) ions/cc for the two negative exposure levels. Rats having a choice between exposure and non-exposure relative to always sham-exposed control animals significantly reduced the amount of time spent on the exposed side at 80 kV/m (P HVdc exposure level was held constant at either -55 kV/m (for three experiments) or -55 kV/m (for 1 experiment) while the air ion concentration was varied between experiments at 2.5 x 10(5) ions/cc, 1.0 x 10(4) for two of the experiments and was below the measurement limit

  12. Harmonics in Offshore Wind Power Plants Employing Power Electronic Devices in the Transmission System

    DEFF Research Database (Denmark)

    Glasdam, Jakob Bærholm

    of wind power. The onshore as well as offshore wind power plants (OWPPs) therefore have to meet the same stringent requirement as the conventional power plants. This can be accommodated by employment of flexible alternating current transmission system (FACTS) devices, such as the static compensator...... gives rise to a number of challenges to the wind power industry with regard to construction, installation as well as transmission of the generated energy. The STATCOM and the voltage-sourced converter high-voltage direct current (VSC-HVDC) are attractive solutions for grid connection of remotely located...... OWPPs. The new system configuration requires in-depth knowledge of all relevant technical aspects, including e.g. the involved control systems performance and robustness for all possible operating conditions. The transmission system operator might impose new control requirements when the VSC...

  13. Stability of DC Voltage Droop Controllers in VSC HVDC Systems

    DEFF Research Database (Denmark)

    Thams, Florian; Suul, Jon Are; D’Arco, Salvatore;

    2015-01-01

    Future multi-terminal HVDC systems are expected to utilize dc voltage droop controllers and several control implementations have been proposed in literature. This paper first classifies possible dc droop implementations in a simple framework. Then, the small-signal stability of a VSC-based conver......Future multi-terminal HVDC systems are expected to utilize dc voltage droop controllers and several control implementations have been proposed in literature. This paper first classifies possible dc droop implementations in a simple framework. Then, the small-signal stability of a VSC...

  14. Transmission line component testing for the ITER Ion Cyclotron Heating and Current Drive System

    Science.gov (United States)

    Goulding, Richard; Bell, G. L.; Deibele, C. E.; McCarthy, M. P.; Rasmussen, D. A.; Swain, D. W.; Barber, G. C.; Barbier, C. N.; Cambell, I. H.; Moon, R. L.; Pesavento, P. V.; Fredd, E.; Greenough, N.; Kung, C.

    2014-10-01

    High power RF testing is underway to evaluate transmission line components for the ITER Ion Cyclotron Heating and Current Drive System. The transmission line has a characteristic impedance Z0 = 50 Ω and a nominal outer diameter of 305 mm. It is specified to carry up to 6 MW at VSWR = 1.5 for 3600 s pulses, with transient voltages up to 40 kV. The transmission line is actively cooled, with turbulent gas flow (N2) used to transfer heat from the inner to outer conductor, which is water cooled. High voltage and high current testing of components has been performed using resonant lines generating steady state voltages of 35 kV and transient voltages up to 60 kV. A resonant ring, which has operated with circulating power of 6 MW for 1 hr pulses, is being used to test high power, low VSWR operation. Components tested to date include gas barriers, straight sections of various lengths, and 90 degree elbows. Designs tested include gas barriers fabricated from quartz and aluminum nitride, and transmission lines with quartz and alumina inner conductor supports. The latest results will be presented. This manuscript has been authored by UT-Battelle, LLC, under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy.

  15. 环网式三端直流输电系统及直流断路器应用的分析与仿真%Analysis and Simulation of Ring-Shaped Three-Terminal HVDC Power Transmission System and Annlication of DC Circuit Breakers

    Institute of Scientific and Technical Information of China (English)

    方进; 邓珂琳; 温家良

    2012-01-01

    分析了多端直流输电系统的基本原理,利用PSCAD/EMTDC软件建立了多端直流输电系统仿真模型,并建立了含直流断路器的多环网式多端直流输电系统模型,通过仿真研究了直流断路器开断直流输电线路的过程,分析直流断路器在环网式多端直流输电系统中的作用。对直流断路器切除环网式三端直流输电系统一条输电线路的过程及切除故障换流站分别进行了仿真分析。仿真结果表明,当利用直流断路器切除环网式多端直流输电系统的一条输电线路时,输电线路的电流重新分配,能保证功率输送的连续性。在这种情况下,对各个换流站输出或输入的功率影响不大,对与直流系统连接的交流输电网影响很小。当切除故障换流站后,该系统最大限度地保持功率传输及电流的有效分配,保持稳定运行。%Basic principles of multi-terminal direct current (MTDC) power transmission system are analyzed, and utilizing PSCAD/EMTDC software a model of MTDC power transmission system and a model of multi ring-shaped MTDC power transmission system containing DC circuit breakers are built. The process of switching off a DC transmission line by DC circuit breakers is simulated and researched, and the action of DC circuit breakers in multi ring-shaped MTDC transmission system is analyzed. The process of switching off one of transmission lines as well as the process of switching off a faulty converter station in three-terminal DC transmission system by DC circuit breakers are simulated respectively. Simulation results show that when one of DC transmission line in ring-shaped MTDC transmission system is switched off by DC circuit breakers, the currents in DC transmission lines are redistributed to ensure the continuity of power transmission. Under such a condition, the affection on input or output power of each converter station is not notable, and the affection on AC

  16. Development of a Peltier Current Lead for the 200-m-Class Superconducting Direct Current Transmission and Distribution System

    Science.gov (United States)

    Kawahara, Toshio; Emoto, Masahiko; Watanabe, Hirofumi; Hamabe, Makoto; Yamaguchi, Sataro; Hikichi, Yasuo; Minowa, Masahiro

    2013-07-01

    Reducing cryogenic heat leaks is critical for superconducting applications. Reduction of heat leak at the terminals is essential for uses with short-length applications, where cryogenic losses at the terminals dominate. We are developing a 200-m-class superconducting direct current (DC) transmission and distribution system (CASER-2), and have used a Peltier current lead (PCL) for heat insulation at the terminals. The PCL consists of thermoelectric elements and copper leads, which enhance the performance of superconducting systems. As DC flows through the current lead, thermoelectric elements on opposite terminations of a superconducting line can be used to decrease the heat ingress to the cryogenic environment ( n-type on one end, p-type on the opposite end). During the current feeding and cooling test, a large temperature difference was observed across thermoelectric elements in the PCL. This demonstrates that we have successfully insulated the heat leak at the current lead. During the fourth cooling test, we established a new PCL design with p-type elements at terminal B, and then compared the performance of the terminals. Several improvements were implemented, including balancing the resistances of the PCL to enhance the stability of the superconducting systems.

  17. A Novel Transient Fault Current Sensor Based on the PCB Rogowski Coil for Overhead Transmission Lines.

    Science.gov (United States)

    Liu, Yadong; Xie, Xiaolei; Hu, Yue; Qian, Yong; Sheng, Gehao; Jiang, Xiuchen

    2016-05-21

    The accurate detection of high-frequency transient fault currents in overhead transmission lines is the basis of malfunction detection and diagnosis. This paper proposes a novel differential winding printed circuit board (PCB) Rogowski coil for the detection of transient fault currents in overhead transmission lines. The interference mechanism of the sensor surrounding the overhead transmission line is analyzed and the guideline for the interference elimination is obtained, and then a differential winding printed circuit board (PCB) Rogowski coil is proposed, where the branch and return line of the PCB coil were designed to be strictly symmetrical by using a joining structure of two semi-rings and collinear twisted pair differential windings in each semi-ring. A serial test is conducted, including the frequency response, linearity, and anti-interference performance as well as a comparison with commercial sensors. Results show that a PCB Rogowski coil has good linearity and resistance to various external magnetic field interferences, thus enabling it to be widely applied in fault-current-collecting devices.

  18. A Novel Transient Fault Current Sensor Based on the PCB Rogowski Coil for Overhead Transmission Lines

    Directory of Open Access Journals (Sweden)

    Yadong Liu

    2016-05-01

    Full Text Available The accurate detection of high-frequency transient fault currents in overhead transmission lines is the basis of malfunction detection and diagnosis. This paper proposes a novel differential winding printed circuit board (PCB Rogowski coil for the detection of transient fault currents in overhead transmission lines. The interference mechanism of the sensor surrounding the overhead transmission line is analyzed and the guideline for the interference elimination is obtained, and then a differential winding printed circuit board (PCB Rogowski coil is proposed, where the branch and return line of the PCB coil were designed to be strictly symmetrical by using a joining structure of two semi-rings and collinear twisted pair differential windings in each semi-ring. A serial test is conducted, including the frequency response, linearity, and anti-interference performance as well as a comparison with commercial sensors. Results show that a PCB Rogowski coil has good linearity and resistance to various external magnetic field interferences, thus enabling it to be widely applied in fault-current-collecting devices.

  19. La conception, la modelisation et la simulation du systeme VSC-HVDC offshore

    Science.gov (United States)

    Benhalima, Seghir

    Wind energy is recognized worldwide as a proven technology to meet the growing demands of green sustainable energy. To exploit this stochastic energy source and put together with the conventional energy sources without affecting the performance of existing electrical grids, several research projects have been achieved. In addition, at ocean level, wind energy has a great potential. It means that the production of this energy will increase in the world. The optimal extraction of this energy source needs to be connected to the grid via a voltage source converter which plays the role of interface. To minimise losses due to the transport of energy at very long distances, the technology called High Voltage Direct Current based on Voltage Source Converter (VSC-HVDC) is used. To achieve this goal, a new topology is designed with a new control algorithm based on control of power generated by the wind farm, the DC voltage regulation and the synchronization between wind farm and VSC-HVDC (based on NPC). The proposed topology and its control technique are validated using the "MATLAB/Simulink program". The results are promising, because the THD is less than 5% and the power factor is close to one.

  20. Nonlinear Control of Back-to-Back VSC-HVDC System via Command-Filter Backstepping

    Directory of Open Access Journals (Sweden)

    Jie Huang

    2017-01-01

    Full Text Available This paper proposed a command-filtered backstepping controller to improve the dynamic performance of back-to-back voltage-source-converter high voltage direct current (BTB VSC-HVDC. First, the principle and model of BTB VSC-HVDC in abc and d-q frame are described. Then, backstepping method is applied to design a controller to maintain the voltage balance and realize coordinated control of active and reactive power. Meanwhile, command filter is introduced to deal with the problem of input saturation and explosion of complexity in conventional backstepping, and a filter compensation signal is designed to diminish the adverse effects caused by the command filter. Next, the stability and convergence of the whole system are proved via the Lyapunov theorem of asymptotic stability. Finally, simulation results are given to demonstrate that proposed controller has a better dynamic performance and stronger robustness compared to the traditional PID algorithm, which also proves the effectiveness and possibility of the designed controller.

  1. HVDC-AC system interaction from AC harmonics. Volume 1. Harmonic impedance calculations. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Breuer, G D; Chow, J H; Lindh, C B; Miller, N W; Numrich, F H; Price, W W; Turner, A E; Whitney, R R

    1982-09-01

    Improved methods are needed to characterize ac system harmonic behavior for ac filter design for HVDC systems. The purpose of this General Electric Company RP1138 research is to evaluate the present filter design practice and to investigate methods for calculating system harmonic impedances. An overview of ac filter design for HVDC systems and a survey of literature related to filter design have been performed. Two methods for calculating system harmonic impedances have been investigated. In the measurement method, an instrumentation system for measuring system voltage and current has been assembled. Different schemes of using the measurements to calculate system harmonic impedances have been studied. In the analytical method, a procedure to include various operating conditions has been proposed. Computer programs for both methods have been prepared, and the results of the measurement and analytical methods analyzed. A conclusion of the project is that the measurement and analytical methods both provided reasonable results. There are correlations between the measured and analytical results for most harmonics, although there are discrepancies between the assumptions used in the two methods. A sensitivity approach has been proposed to further correlate the results. From the results of the analysis, it is recommended that both methods should be tested further. For the measurement method, more testing should be done to cover different system operating conditions. In the analytical method, more detailed models for representing system components should be studied. In addition, alternative statistical and sensitivity approaches should be attempted.

  2. HVDC-AC system interaction from AC harmonics. Volume 1. Harmonic impedance calculations. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Breuer, G D; Chow, J H; Lindh, C B; Miller, N W; Numrich, F H; Price, W W; Turner, A E; Whitney, R R

    1982-09-01

    Improved methods are needed to characterize ac system harmonic behavior for ac filter design for HVDC systems. The purpose of this General Electric Company RP1138 research is to evaluate the present filter design practice and to investigate methods for calculating system harmonic impedances. An overview of ac filter design for HVDC systems and a survey of literature related to filter design have been performed. Two methods for calculating system harmonic impedances have been investigated. In the measurement method, an instrumentation system for measuring system voltage and current has been assembled. Different schemes of using the measurements to calculate system harmonic impedances have been studied. In the analytical method, a procedure to include various operating conditions has been proposed. Computer programs for both methods have been prepared, and the results of the measurement and analytical methods analyzed. A conclusion of the project is that the measurement and analytical methods both provided reasonable results. There are correlations between the measured and analytical results for most harmonics, although there are discrepancies between the assumptions used in the two methods. A sensitivity approach has been proposed to further correlate the results. From the results of the analysis, it is recommended that both methods should be tested further. For the measurement method, more testing should be done to cover different system operating conditions. In the analytical method, more detailed models for representing system components should be studied. In addition, alternative statistical and sensitivity approaches should be attempted.

  3. Transmission routes of African swine fever virus to domestic pigs: current knowledge and future research directions.

    Science.gov (United States)

    Guinat, Claire; Gogin, Andrey; Blome, Sandra; Keil, Guenther; Pollin, Reiko; Pfeiffer, Dirk U; Dixon, Linda

    2016-03-12

    African swine fever (ASF) is a major threat to the pig industry in Europe. Since 2007, ASF outbreaks have been ongoing in the Caucasus, Eastern Europe and the Baltic countries, causing severe economic losses for many pig farmers and pork producers. In addition, the number of ASF cases in wild boar populations has dramatically increased over the past few years. Evidence supports direct contact with infectious domestic pigs and wild boars, and consumption of contaminated feed, as the main transmission routes of ASF virus (ASFV) to domestic pigs. However, significant knowledge gaps highlight the urgent need for research to investigate the dynamics of indirect transmission via the environment, the minimal infective doses for contaminated feed ingestion, the probability of effective contacts between infectious wild boars and domestic pigs, the potential for recovered animals to become carriers and a reservoir for transmission, the potential virus persistence within wild boar populations and the influence of human behaviour for the spread of ASFV. This will provide an improved scientific basis to optimise current interventions and develop new tools and strategies to reduce the risk of ASFV transmission to domestic pigs.

  4. Global elimination of mother-to-child transmission of hepatitis B: revisiting the current strategy.

    Science.gov (United States)

    Thio, Chloe L; Guo, Nan; Xie, Chan; Nelson, Kenrad E; Ehrhardt, Stephan

    2015-08-01

    Mother-to-child transmission (MTCT) of hepatitis B virus (HBV) is a major route of HBV transmission worldwide despite an existing immunoprophylaxis regimen. The implementation of immunoprophylaxis has been challenging, especially in low-income and middle-income countries, where MTCT is common, because of difficulty obtaining and delivering the monovalent HBV vaccine and the HBV immunoglobulin. Global control of the HBV epidemic will need improved prevention of MTCT. We discuss research gaps that hinder development of new options for the elimination of MTCT as well as policy changes that may help the current vaccine-based strategy to live up to its full potential. We propose that decreasing hepatitis B viral concentrations before delivery, along with HBV vaccine use, could provide an alternative strategy that would decrease MTCT of HBV.

  5. A Comparative Parametric Analysis of the Ground Fault Current Distribution on Overhead Transmission Lines

    Directory of Open Access Journals (Sweden)

    VINTAN, M.

    2016-02-01

    Full Text Available The ground fault current distribution in an effectively grounded power network is affected by various factors, such as: tower footing impedances, spans lengths, configuration and parameters of overhead ground wires and power conductors, soil resistivity etc. In this paper, we comparatively analyze, using different models, the ground fault current distribution in a single circuit transmission line with one ground wire. A parametric comparative analysis was done in order to study the effects of the non-uniformity of the towers footing impedances, number of power lines spans, soil resistivity, grounding systems resistances of the terminal substations etc., on the ground fault current distribution. There are presented some useful qualitative and quantitative results obtained through a complex dedicated developed MATLAB 7.0 program.

  6. Current transmission and nonlinear effects in un-gated thermionic cathode RF guns

    Energy Technology Data Exchange (ETDEWEB)

    Edelen, J. P. [Fermilab; Harris, J. R. [Air Force Weapons Lab

    2017-05-03

    Un-gated thermionic cathode RF guns are well known as a robust source of electrons for many accelerator applications. These sources are in principle scalable to high currents without degradation of the transverse emittance due to control grids but they are also known for being limited by back-bombardment. While back-bombardment presents a significant limitation, there is still a lack of general understanding on how emission over the whole RF period will affect the nature of the beams produced from these guns. In order to improve our understanding of how these guns can be used in general we develop analytical models that predict the transmission efficiency as a function of the design parameters, study how bunch compression and emission enhancement caused by Schottky barrier lowering affect the output current profile in the gun, and study the onset of space-charge limited effects and the resultant virtual cathode formation leading to a modulation in the output current distribution.

  7. Generic Models of Wind Turbine Generators for Advanced Applications in a VSC-based Offshore HVDC Network

    DEFF Research Database (Denmark)

    Zeni, Lorenzo; Margaris, Ioannis; Hansen, Anca Daniela;

    This paper focuses on generic Type 4 wind turbine generators models, their applicability in modern HVDC connections and their capability to provide advanced ancillary services therefrom. A point-to-point HVDC offshore connection is considered. Issues concerning coordinated HVDC and wind farm...... involving the HVDC converters- The performance against frequency disturbances of the two presented configurations is assessed and discussed by means of simulations....

  8. Current and field distributions of a superconducting power transmission cable composed of helical tape conductors

    Science.gov (United States)

    Tominaka, Toshiharu

    2009-12-01

    The current distributions within a power transmission cable composed of helically wound long tape superconductors have been studied by solving the circuit equation with the inductance matrix among divided segments within a tape conductor under the Bean model. The self- and mutual inductances of helical thin tape conductors are calculated from the analytical expressions in the form of an infinite series. In addition, it is shown that the distinction between the right-handed and left-handed helixes is generally necessary in the mutual inductance between two long coaxial helical conductors.

  9. Current and field distributions of a superconducting power transmission cable composed of helical tape conductors

    Energy Technology Data Exchange (ETDEWEB)

    Tominaka, Toshiharu, E-mail: tominaka@mext.go.j, E-mail: tominaka@riken.j [Ministry of Education, Culture, Sports, Science and Technology (MEXT), 3-2-2 Kasumigaseki, Chiyoda-ku, Tokyo 100-8959 (Japan); RIKEN - Institute of Physical and Chemical Research, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan)

    2009-12-15

    The current distributions within a power transmission cable composed of helically wound long tape superconductors have been studied by solving the circuit equation with the inductance matrix among divided segments within a tape conductor under the Bean model. The self- and mutual inductances of helical thin tape conductors are calculated from the analytical expressions in the form of an infinite series. In addition, it is shown that the distinction between the right-handed and left-handed helixes is generally necessary in the mutual inductance between two long coaxial helical conductors.

  10. Simulating malaria transmission in the current and future climate of West Africa

    Science.gov (United States)

    Yamana, T. K.; Bomblies, A.; Eltahir, E. A. B.

    2015-12-01

    Malaria transmission in West Africa is closely tied to climate, as rain fed water pools provide breeding habitat for the anopheles mosquito vector, and temperature affects the mosquito's ability to spread disease. We present results of a highly detailed, spatially explicit mechanistic modelling study exploring the relationships between the environment and malaria in the current and future climate of West Africa. A mechanistic model of human immunity was incorporated into an existing agent-based model of malaria transmission, allowing us to move beyond entomological measures such as mosquito density and vectorial capacity to analyzing the prevalence of the malaria parasite within human populations. The result is a novel modelling tool that mechanistically simulates all of the key processes linking environment to malaria transmission. Simulations were conducted across climate zones in West Africa, linking temperature and rainfall to entomological and epidemiological variables with a focus on nonlinearities due to threshold effects and interannual variability. Comparisons to observations from the region confirmed that the model provides a reasonable representation of the entomological and epidemiological conditions in this region. We used the predictions of future climate from the most credible CMIP5 climate models to predict the change in frequency and severity of malaria epidemics in West Africa as a result of climate change.

  11. Control and Protection of Wind Power Plants with VSC-HVDC Connection

    DEFF Research Database (Denmark)

    Chaudhary, Sanjay

    Wind power plants are the fastest growing source of renewable energy. The European Union expects to generate 230 GW wind power, in which the offshore wind power is expected to contribute 40 GW. Offshore wind power plants have better wind velocity profile leading to a higher energy yield. Europe has...... a huge potential of offshore wind energy, which is a green and sustainable resource. All these have led to the development of offshore wind power plants. However, overall cost of the offshore installation, operation, and maintenance are higher than those of the onshore wind power plants. Therefore...... oscillations, and hence, lower dc voltage overshoots in the VSC-HVDC system. On the protection side, the coordination of over-current relays has been analysed in the new environment. A simple yet reliable scheme utilizing the well-known over-current relay characteristics has been presented for the detection...

  12. Capacitor voltage ripple reduction and arm energy balancing in MMC-HVDC

    DEFF Research Database (Denmark)

    Martin-Loeches, Ruben Sánches; Parikh, Harsh; Tsolaridis, Georgios

    2016-01-01

    Modular Multilevel Converters are emerging and widely used in HVDC applications. However, the submodule capacitors are still large and the energy balancing under unbalanced conditions is a challenge. In this paper, an analytical model focusing on the energy stored in the capacitors and voltage...... variations is utilized in order to achieve better performance. By injecting a second order harmonic component into the circulating current, the energy variation and consequently the capacitor voltage ripple is reduced allowing for a capacitor size reduction. At the same time, an arm energy balancing...... controller has been proposed which uses the first harmonic of the circulating current in order to keep the energy balance of the leg under internal unbalanced conditions....

  13. Component development for the ITER Ion Cyclotron Heating and Current Drive Transmission Line and Matching System

    Science.gov (United States)

    Goulding, R. H.; McCarthy, M. P.; Rasmussen, D. A.; Swain, D. W.; Barber, G. C.; Barbier, C. N.; Cambell, I. H.; Gray, S. L.; Moon, R. L.; Pesavento, P. V.; Sanabria, R. M.; Fredd, E.; Greenough, N.

    2013-10-01

    The transmission line and matching network for the ITER Ion Cyclotron Heating and Current Drive System feeds two equatorial launchers, each with 24 phased current straps combined into groups of three, and each designed to couple up to 20 MW into ELMy H-mode plasmas in the frequency range 40-55 MHz, for pulse lengths up to 3600 s. The network includes > 1 km of 50 Ohm 300 mm diameter transmission line carrying up to 6 MW net power per line at VSWR = 1.5. In addition, there are 8 power splitters, 32 hybrid phase shifters incorporating 64 tuning stubs, 32 additional tuning stubs, and 36 vacuum capacitors, which are configured to provide pre-matching in the port cell region adjacent to the antenna, final matching, decoupling of mutual inductances between antenna elements, and passive ELM resilience. The development and design of the various system components will be discussed. High power tests of components have begun, and the latest results will be presented. This manuscript has been authored by UT-Battelle, LLC, under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy.

  14. A vacuum sealed high emission current and transmission efficiency carbon nanotube triode

    Directory of Open Access Journals (Sweden)

    Yunsong Di

    2016-04-01

    Full Text Available A vacuum sealed carbon nanotubes (CNTs triode with a concave and spoke-shaped Mo grid is presented. Due to the high aperture ratio of the grid, the emission current could be modulated at a relatively high electric field. Totally 75mA emission current has been obtained from the CNTs cathode with the average applied field by the grid shifting from 8 to 13 V/μm. Whilst with the electron transmission efficiency of the grid over 56%, a remarkable high modulated current electron beam over 42mA has been collected by the anode. Also contributed by the high aperture ration of the grid, desorbed gas molecules could flow away from the emission area rapidly when the triode has been operated at a relative high emission current, and finally collected by a vacion pump. The working pressure has been maintained at ∼1 × 10−7 Torr, seldom spark phenomena occurred. Nearly perfect I-V curve and corresponding Fowler-Nordheim (FN plot confirmed the accuracy of the measured data, and the emission current was long term stable and reproducible. Thusly, this kind of triode would be used as a high-power electron source.

  15. A vacuum sealed high emission current and transmission efficiency carbon nanotube triode

    Science.gov (United States)

    Di, Yunsong; Wang, Qilong; Zhang, Xiaobing; Lei, Wei; Du, Xiaofei; Yu, Cairu

    2016-04-01

    A vacuum sealed carbon nanotubes (CNTs) triode with a concave and spoke-shaped Mo grid is presented. Due to the high aperture ratio of the grid, the emission current could be modulated at a relatively high electric field. Totally 75mA emission current has been obtained from the CNTs cathode with the average applied field by the grid shifting from 8 to 13 V/μm. Whilst with the electron transmission efficiency of the grid over 56%, a remarkable high modulated current electron beam over 42mA has been collected by the anode. Also contributed by the high aperture ration of the grid, desorbed gas molecules could flow away from the emission area rapidly when the triode has been operated at a relative high emission current, and finally collected by a vacion pump. The working pressure has been maintained at ˜1 × 10-7 Torr, seldom spark phenomena occurred. Nearly perfect I-V curve and corresponding Fowler-Nordheim (FN) plot confirmed the accuracy of the measured data, and the emission current was long term stable and reproducible. Thusly, this kind of triode would be used as a high-power electron source.

  16. A vacuum sealed high emission current and transmission efficiency carbon nanotube triode

    Energy Technology Data Exchange (ETDEWEB)

    Di, Yunsong [School of Electronic Science & Engineering, Southeast University, Nanjing 210096 (China); Jiangsu Key Laboratory of Optoelectronic Technology, Nanjing Normal University, Nanjing 210023 (China); Wang, Qilong; Zhang, Xiaobing, E-mail: bell@seu.edu.cn; Lei, Wei; Du, Xiaofei; Yu, Cairu [School of Electronic Science & Engineering, Southeast University, Nanjing 210096 (China)

    2016-04-15

    A vacuum sealed carbon nanotubes (CNTs) triode with a concave and spoke-shaped Mo grid is presented. Due to the high aperture ratio of the grid, the emission current could be modulated at a relatively high electric field. Totally 75 mA emission current has been obtained from the CNTs cathode with the average applied field by the grid shifting from 8 to 13 V/μm. Whilst with the electron transmission efficiency of the grid over 56%, a remarkable high modulated current electron beam over 42 mA has been collected by the anode. Also contributed by the high aperture ration of the grid, desorbed gas molecules could flow away from the emission area rapidly when the triode has been operated at a relative high emission current, and finally collected by a vacion pump. The working pressure has been maintained at ∼1 × 10{sup −7} Torr, seldom spark phenomena occurred. Nearly perfect I-V curve and corresponding Fowler-Nordheim (FN) plot confirmed the accuracy of the measured data, and the emission current was long term stable and reproducible. Thusly, this kind of triode would be used as a high-power electron source.

  17. Discrete-Time Nonlinear Control of VSC-HVDC System

    Directory of Open Access Journals (Sweden)

    TianTian Qian

    2015-01-01

    Full Text Available Because VSC-HVDC is a kind of strong nonlinear, coupling, and multi-input multioutput (MIMO system, its control problem is always attracting much attention from scholars. And a lot of papers have done research on its control strategy in the continuous-time domain. But the control system is implemented through the computer discrete sampling in practical engineering. It is necessary to study the mathematical model and control algorithm in the discrete-time domain. The discrete mathematical model based on output feedback linearization and discrete sliding mode control algorithm is proposed in this paper. And to ensure the effectiveness of the control system in the quasi sliding mode state, the fast output sampling method is used in the output feedback. The results from simulation experiment in MATLAB/SIMULINK prove that the proposed discrete control algorithm can make the VSC-HVDC system have good static, dynamic, and robust characteristics in discrete-time domain.

  18. Efficiency of VSC-HVDC System With Various Fuzzy Models

    Directory of Open Access Journals (Sweden)

    Mrs. Sonali R dasgupta,

    2011-05-01

    Full Text Available This paper suggests a Shrinking Span Membership function to be utilized in very fact changing system just like VSC- HVDC system. In this particular work Mamdani controller as well as the Takagi-Sugeno controller are compared with exact same input function(Shrinking Span Membership in simulation as well as on prototype hardware. Simulation result justify the. Takagi-Sugeno Controller gives better dynamic response then the Mamdani controller

  19. Current Sharing Technology in Transmission Conductors of Cold Dielectric High Temperature Superconducting Cables Using Second-generation HTS Wires

    Institute of Scientific and Technical Information of China (English)

    ZHU Jiahui; BAO Xuzheng; QIU Ming

    2012-01-01

    The cold dielectric high temperature superconducting (CD HTS) cable has multilayer conductors. The non-uniform AC current distribution in these multilayer conductors will increase the AC loss and decrease the current transmission efficiency. So it is important to understand the current sharing among layers in order to fully exploit the performance of the HTS cable.

  20. Analysis of MMC-HVDC Transient Response Characteristic Under Typical Disturbances%MMC-HVDC典型扰动暂态响应特性分析

    Institute of Scientific and Technical Information of China (English)

    马雅青; 王卫安; 张杰; 唐剑钊; 任涛

    2011-01-01

    为揭示具有新型拓扑结构的基于模块化多电平换流器直流输电系统MMC-HVDC(modular multilevel converter high voltage direct current)的电磁暂态特性,对该系统进行典型扰动暂态响应的特性分析根据MMC拓扑结构,推导了交流电网不平衡时的MMC交流侧电磁暂态模型,并基于模型设计了正、负序双内环电流控制和外环功率控制的控制策略.同时,对MMC-HVDC在各种典型扰动下的暂态响应特性进行了详细的仿真分析,仿真结果表明所设计的控制策略的正确性.MMC-HVDC在遭受各种典型扰动时具有良好的暂态响应特性,并能稳定、充裕地运行.%In order to reveal the electromagnetic transient characteristics of new topology structure MMC HVDC.it is necessary to study the transient response characteristics of the new HVDC under various typical disturbances. According to the topology structure of MMCthe electromagnetic transient model of AC side of MMC was derived under the condition of unbalance AC grid. The control strategies with inneer loops current control of positive and negative sequence and an outer loop's power control were designed. With various typical disturbances simulations,the transient response of MMC-HVDC was designed. With various typical disturb ances simulations,the transient response of MMC-HVDC was studied and the correctness of the proposed con trol strategy was confirmed. MMC-HVDC has good transient response characteristics, and can operate stably and fully under various typical disturbances.

  1. Effects of Electron Flow Current Density on Flow Impedance of Magnetically Insulated Transmission Lines

    Institute of Scientific and Technical Information of China (English)

    HE Yong; ZOU Wen-Kang; SONG Sheng-Yi

    2011-01-01

    @@ In modern pulsed power systems, magnetically insulated transmission lines (MITLs) are used to couple power between the driver and the load.The circuit parameters of MITLs are well understood by employing the concept of Sow impedance derived from Maxwell's equations and pressure balance across the flow.However, the electron density in an MITL is always taken as constant in the application of flow impedance.Thus effects of electron flow current density (product of electron density and drift velocity) in an MITL are neglected.We calculate the flow impedances of an MITL and compare them under three classical MITL theories, in which the electron density profile and electron flow current density are different from each other.It is found that the assumption of constant electron density profile in the calculation of the Sow impedance is not always valid.The electron density profile and the electron flow current density have significant effects on flow impedance of the MITL.The details of the electron flow current density and its effects on the operation impedance of the MITL should be addressed more explicitly experiments and theories in the future.

  2. A Primal-Dual Interior Point Method-Based Algorithm Adopting Automatic Differentiation for Optimal Power Flow of AC/DC Power Grid Containing VSC-HVDC System%基于自动微分技术的VSC-HVDC内点法最优潮流

    Institute of Scientific and Technical Information of China (English)

    季聪; 卫志农; 汤涌; 孙国强; 韦延方; 孙永辉

    2012-01-01

    Based on steady state power flow model of voltage source converter-high voltage direct current (VSC-HVDC) power transmission system and combining with automatic differentiation (AD) technology, a primal-dual interior point method-based algorithm for optimal power flow (OPF) of AC/DC power grid was proposed. Using high efficient AD tool based on operator overloading the Jacobian and Hessian matrices were generated, thus the work load for derivation of differential expressions and code compiling could be reduced and the development efficiency of program could be improved. Simulation results of calculation examples showed that in the solution of OPF problem of AC/DC power grid containing VSC-HVDC power transmission system the high efficiency of traditional primal-dual interior point method could be kept and it possessed satisfied adaptability to the combination of different VSC control modes.%根据电压源换流器-高压直流输电(voltage source converter-high voltage direct current,VSC-HVDC)的稳态潮流模型,结合自动微分(automatic differentiation,AD)技术,提出一种基于原对偶内点法的交直流系统最优潮流算法.该算法利用高效的基于操作符重载的AD工具生成雅可比(Jacobian)矩阵和海森(Hessian)矩阵,减少了微分表达式推导和代码编写的工作量,提高了程序的开发效率.多个算例的仿真结果表明,该算法保持了传统原对偶内点法在解决含VSC-HVDC的交直流最优潮流问题上的高效性,且对VSC的不同控制方式组合均具有良好的适应性.

  3. Zinc Oxide Surge Arresters and HVDC 125kV-upgrade 500kV Converter Stations

    Science.gov (United States)

    Shirakawa, Shingo; Kobayashi, Takayuki; Matsushita, Yoshinao; Sakai, Takehisa; Suzuki, Hironori; Ozaki, Yuzo

    Gapless Metal (Zinc) Oxide Surge Arresters for a.c. systems contribute to the insulation co-ordination based on the suppression of lightning surges and switching surges. These gapless metal oxide surge arresters using ZnO elements are effective to HVDC systems. This paper describes basic characteristics of ZnO (zinc oxide) elements for d.c. systems and applications of gapless surge arresters to HVDC 125kV frequency converters, HVDC 250kV, upgrade HVDC 500kV converter stations, and HVDC 500kV cables of Japan through the experience of developments and applications of gapless metal oxide surge arresters.

  4. The quantum Kirchhoff equation and quantum current and energy spectrum of a homogeneous mesoscopic dissipation transmission line

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    On the basis of quantization of charge, the loop equations of quantum circuits are investigated by using the Heisenberg motion equation for a mesoscopic dissipation transmission line. On the supposition that the system has a symmetry under translation in charge space, the quantum current and the quantum energy spectrum in the mesoscopic transmission line are given by solving their eigenvalue equations. Results show that the quantum current and the quantum energy spectrum are not only related to the parameters of the transmission line, but also dependent on the quantized character of the charge obviously.

  5. Control of a hybrid HVDC link to increase inter-regional power transfer

    DEFF Research Database (Denmark)

    Kotb, Omar; Ghandhari, Mehrdad; Eriksson, Robert

    2016-01-01

    This paper examines the application of a hybrid HVDC link in a two area power system with the purpose of increasing the inter-regional power transfer. A hybrid HVDC system combines both LCCs and VSCs, and hence it is capable of combining the benefits of both converter technologies, such as reduced...... cost and power losses due to the LCCs, and ability to connect to weak AC grids due to the VSCs. The mathematical model of the power system including the HVDC link is presented. The increase in inter-area power transfer is demonstrated and compared to the case when the hybrid HVDC link is not used....... Furthermore, the transient stability of the AC/DC power system was enhanced using auxiliary controllers for Power Oscillation Damping (POD). The results show the ability of the hybrid HVDC link to increase the unidirectional inter-area power transfer, while enhancing the transient stability of the power...

  6. Transient Voltage Stability Analysis and Improvement of A Network with different HVDC Systems

    DEFF Research Database (Denmark)

    Liu, Yan; Chen, Zhe

    2011-01-01

    the theoretical analysis and the improved control method, real time simulation model of a hybrid multi-infeed HVDC system based on western Danish power system is established in RTDS™. Simulation results show that the enhanced transient voltage stability can be achieved.......This paper presents transient voltage stability analysis of an AC system with multi-infeed HVDC links including a traditional LCC HVDC link and a VSC HVDC link. It is found that the voltage supporting capability of the VSC-HVDC link is significantly influenced by the tie-line distance between...... the two links and the size of loads. In order to improve the transient voltage stability, a voltage adjusting method is proposed in this paper. A voltage increment component has been introduced into the outer voltage control loop under emergency situation caused by severe grid faults. In order to verify...

  7. OPF-Based Optimal Location of Two Systems Two Terminal HVDC to Power System Optimal Operation

    Directory of Open Access Journals (Sweden)

    Mehdi Abolfazli

    2013-04-01

    Full Text Available In this paper a suitable mathematical model of the two terminal HVDC system is provided for optimal power flow (OPF and optimal location based on OPF such power injection model. The ability of voltage source converter (VSC-based HVDC to independently control active and reactive power is well represented by the model. The model is used to develop an OPF-based optimal location algorithm of two systems two terminal HVDC to minimize the total fuel cost and active power losses as objective function. The optimization framework is modeled as non-linear programming (NLP and solved by Matlab and GAMS softwares. The proposed algorithm is implemented on the IEEE 14- and 30-bus test systems. The simulation results show ability of two systems two terminal HVDC in improving the power system operation. Furthermore, two systems two terminal HVDC is compared by PST and OUPFC in the power system operation from economical and technical aspects.

  8. µ-Conotoxins Modulating Sodium Currents in Pain Perception and Transmission: A Therapeutic Potential

    Directory of Open Access Journals (Sweden)

    Elisabetta Tosti

    2017-09-01

    Full Text Available The Conus genus includes around 500 species of marine mollusks with a peculiar production of venomous peptides known as conotoxins (CTX. Each species is able to produce up to 200 different biological active peptides. Common structure of CTX is the low number of amino acids stabilized by disulfide bridges and post-translational modifications that give rise to different isoforms. µ and µO-CTX are two isoforms that specifically target voltage-gated sodium channels. These, by inducing the entrance of sodium ions in the cell, modulate the neuronal excitability by depolarizing plasma membrane and propagating the action potential. Hyperexcitability and mutations of sodium channels are responsible for perception and transmission of inflammatory and neuropathic pain states. In this review, we describe the current knowledge of µ-CTX interacting with the different sodium channels subtypes, the mechanism of action and their potential therapeutic use as analgesic compounds in the clinical management of pain conditions.

  9. Harmonic Resonance in Power Transmission Systems due to the Addition of Shunt Capacitors

    Science.gov (United States)

    Patil, Hardik U.

    Shunt capacitors are often added in transmission networks at suitable locations to improve the voltage profile. In this thesis, the transmission system in Arizona is considered as a test bed. Many shunt capacitors already exist in the Arizona transmission system and more are planned to be added. Addition of these shunt capacitors may create resonance conditions in response to harmonic voltages and currents. Such resonance, if it occurs, may create problematic issues in the system. It is main objective of this thesis to identify potential problematic effects that could occur after placing new shunt capacitors at selected buses in the Arizona network. Part of the objective is to create a systematic plan for avoidance of resonance issues. For this study, a method of capacitance scan is proposed. The bus admittance matrix is used as a model of the networked transmission system. The calculations on the admittance matrix were done using Matlab. The test bed is the actual transmission system in Arizona; however, for proprietary reasons, bus names are masked in the thesis copy intended for the public domain. The admittance matrix was obtained from data using the PowerWorld Simulator after equivalencing the 2016 summer peak load (planning case). The full Western Electricity Coordinating Council (WECC) system data were used. The equivalencing procedure retains only the Arizona portion of the WECC. The capacitor scan results for single capacitor placement and multiple capacitor placement cases are presented. Problematic cases are identified in the form of 'forbidden response. The harmonic voltage impact of known sources of harmonics, mainly large scale HVDC sources, is also presented. Specific key results for the study indicated include: (1) The forbidden zones obtained as per the IEEE 519 standard indicates the bus 10 to be the most problematic bus. (2) The forbidden zones also indicate that switching values for the switched shunt capacitor (if used) at bus 3 should be

  10. Development of toroid-type HTS DC reactor series for HVDC system

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kwangmin, E-mail: kwangmin81@gmail.com [Changwon National University, 55306 Sarim-dong, Changwon 641-773 (Korea, Republic of); Go, Byeong-Soo; Park, Hea-chul; Kim, Sung-kyu; Kim, Seokho [Changwon National University, 55306 Sarim-dong, Changwon 641-773 (Korea, Republic of); Lee, Sangjin [Uiduk University, Gyeongju 780-713 (Korea, Republic of); Oh, Yunsang [Vector Fields Korea Inc., Pohang 790-834 (Korea, Republic of); Park, Minwon; Yu, In-Keun [Changwon National University, 55306 Sarim-dong, Changwon 641-773 (Korea, Republic of)

    2015-11-15

    Highlights: • The authors developed the 400 mH, 400 A class toroid-type HTS DC reactor system. • The target temperature, inductance and operating current are under 20 K at magnet, 400 mH and 400 A, respectively. All target performances of the HTS DC reactor were achieved. • The HTS DC reactor was conducted through the interconnection operation with a LCC type HVDC system. • Now, the authors are studying the 400 mH, 1500 A class toroid-type HTS DC reactor for the next phase HTS DC reactor. - Abstract: This paper describes design specifications and performance of a toroid-type high-temperature superconducting (HTS) DC reactor. The first phase operation targets of the HTS DC reactor were 400 mH and 400 A. The authors have developed a real HTS DC reactor system during the last three years. The HTS DC reactor was designed using 2G GdBCO HTS wires. The HTS coils of the toroid-type DC reactor magnet were made in the form of a D-shape. The electromagnetic performance of the toroid-type HTS DC reactor magnet was analyzed using the finite element method program. A conduction cooling method was adopted for reactor magnet cooling. The total system has been successfully developed and tested in connection with LCC type HVDC system. Now, the authors are studying a 400 mH, kA class toroid-type HTS DC reactor for the next phase research. The 1500 A class DC reactor system was designed using layered 13 mm GdBCO 2G HTS wire. The expected operating temperature is under 30 K. These fundamental data obtained through both works will usefully be applied to design a real toroid-type HTS DC reactor for grid application.

  11. Equivalent Circuit for Half-Bridge MMC Dc Fault Current Contribution

    OpenAIRE

    Leterme, Willem; Beerten, Jef; Van Hertem, Dirk

    2016-01-01

    The modular multilevel converter (MMC) is currently the preferred converter topology for HVDC point-to-point links and the likely choice for future meshed HVDC grids. For breaker dimensioning or protection system design, thorough knowledge of the dc fault currents supplied by these converters is required. In this paper, the dc fault current supplied by the half-bridge MMC is analyzed and an equivalent circuit model is proposed. The proposed equivalent circuit has a low complexity and accurate...

  12. 高压输电技术的发展评述%Review on the Development of High Voltage Transmission Technology

    Institute of Scientific and Technical Information of China (English)

    李远景

    2014-01-01

    高压直流输电相比交流输电在增强系统的可靠性、限制电路系统的短路容量、完成系统的非同步联网等方面具备显著的优势。结合近年来高压直流技术的发展,综述了目前应用的主要方面,并对未来的研究方向进行了分析。%Compared with alternating current transmission, high voltage direct current transmission (HVDC) has significant advantages in strengthening the reliability of the system,limiting short circuit capacity of the circuit system and completing the non-synchronous networking. Combined with the development of high voltage direct current technology in recent years,the main application aspects are reviewed and future research directions are analyzed.

  13. 背靠背VSC-HVDC的多目标优化布点%Multi-Objective Optimal Allocation of Back-to-BackVSC-HVDC

    Institute of Scientific and Technical Information of China (English)

    关玉衡; 汪隆君; 王钢

    2016-01-01

    电网间的电气联系日趋紧密,多个500 kV变电站短路电流接近或超过断路器遮断容量,严重威胁电网安全。采用背靠背电压源换流器型高压直流输电(voltage source convertor-based high voltage direct current,VSC-HVDC)技术限制短路电流的方案获得业界的关注和认同。在分析VSC-HVDC 降低短路电流原理的基础上,建立以短路电流降低综合效果和投资经济性最优为目标的VSC-HVDC多目标优化布点模型,并采用快速非支配排序遗传算法求解;通过多端口网络等值模型约简可行解空间,以提高个体适应度评估速度;基于模糊选择策略获得最优折中分期建设方案。以2015年夏大运行方式的广东电网为算例,验证表明:1)短路电流降低综合效果指标能有效反映限流措施效果和作用范围;2)多端口网络等值能大幅提高算法求解效率;3)综合限流效果与配置点短路电流大小无直接关系。%Electrical connection between power grids becomes increasingly closer. Short-circuit currents of several 500kVsubstations approach or exceed breaking capability of circuit breakers, seriously threatening safe operation of power grid. Scheme of back-to-back voltage source convertor-based HVDC (VSC-HVDC) technology for short-circuit current limiting attracts more and more attention and gets recognition from power industry. Based on analyzing principle of using VSC-HVDC to reduce short-circuit current, multi-objective optimal allocation model of VSC-HVDC is established with objectives of optimizing comprehensive effects of reducing short-circuit current and investment economy. Non-dominated sorting genetic algorithm-II is employed to solve the proposed model. In order to improve speed of individual fitness evaluation, feasible solution space is reduced with multi-port network equivalent model. Fuzzy selection strategy is used to obtain optimal compromised phased construction scheme

  14. System Aspects and Modulation Strategies of an HVDC-based Converter System for Wind Farms

    Energy Technology Data Exchange (ETDEWEB)

    Meier, Stephan

    2009-05-15

    In this thesis, a new HVDC-based converter system for wind farms is investigated. It is based on a mutually commutated soft-switching converter system and provides a unique integrated solution for the wind turbine generator drive systems, the wind turbine interconnection, and the power conversion for HVDC transmission. In a wind farm, the mutually commutated converter system is a distributed system. A medium-frequency collection grid connects the converter station, equipped with a single-phase voltage source converter and a medium-frequency transmission transformer, with the wind turbines, each containing a cyclo converter and a medium-frequency distribution transformer. In this thesis, various system aspects regarding the application of a distributed mutually commutated converter system in a wind farm are investigated. Special attention is paid to the design of a medium-frequency collection grid that has an acceptable level of transient over voltages, the design of medium-frequency transformers with suitable magnetic, electric and thermal properties, and the development of a strategy to commutate the voltage source converter during low power generation. In order to adapt the mutually commutated converter system for an application in a wind farm, it had to be further developed. Different carrier-based and space-vector oriented modulation methods have been investigated. It turns out that for any load angle there is a quasi-discontinuous pulse width modulation strategy that can produce the same pulse patterns as space vector modulation. In addition, a modulation strategy has been developed that allows to replace the IGBTs in the cyclo converter with cheap, robust, and reliable fast thyristors, despite their absence of turn-off capability. The feasibility of different modulation strategies for mutually commutated converter systems has been verified on a down-scaled prototype converter system with both IGBT- and thyristor-based cyclo converters. Finally, a feasible

  15. Integral Plus Resonant Sliding Mode Direct Power Control for VSC-HVDC Systems under Unbalanced Grid Voltage Conditions

    Directory of Open Access Journals (Sweden)

    Weipeng Yang

    2017-10-01

    Full Text Available An integral plus resonant sliding mode direct power control (IRSMC DPC strategy for voltage source converter high voltage direct current (VSC-HVDC systems under unbalanced grid voltage conditions is proposed in this paper. Through detailed instantaneous power flow analysis, a generalized power compensation method, by which the ratio between the amplitude of active and reactive power ripples can be controlled continuously, is obtained. This enables the system to provide flexible power control, so that the desired performance of the system on both the ac and dc sides can be attained under different operating conditions. When the grid voltage is unbalanced, one or both of the active and reactive power terms contain ripples, oscillating at twice the grid frequency, to obtain non-distorted ac current. A power controller consisting of the proportional, integral and resonant control laws is designed using the sliding mode control approach, to achieve accurate power control objective. Simulation studies on a two-terminal VSC-HVDC system using MATLAB/SIMULINK (R2013b, Mathworks, Natick, MA, USA are conducted to verify the effectiveness of the IRSMC DPC strategy. The results show that this strategy ensures satisfactory performance of the system over a wide range of operating conditions.

  16. Evaluation of HVDC interconnection models for considering its impact in real-time voltage stability assessment

    DEFF Research Database (Denmark)

    Perez, Angel; Jóhannsson, Hjörtur; Lund, P.;

    2015-01-01

    An approach to evaluate the HVDC interconnectionsmodels to be used in real-time voltage stability assessment is proposed.The existing models for the HVDC interconnections, thatare based on voltage source converter, were studied selecting theones that are suitable for its application in Thevenin...... equivalent ´methods for voltage stability assessment. The proposed methodis to evaluate the validity of the models by using synthetizedPMU measurements from simulations and from PMUs connectedto the danish system. Wide-area measurements are used toestimate the HVDC model parameters which are needed...

  17. Cluster Control of Offshore Wind Power Plants Connected to a Common HVDC Station

    DEFF Research Database (Denmark)

    Göksu, Ömer; Sakamuri, Jayachandra N.; Rapp, C. Andrea;

    2016-01-01

    In this paper a coordinated control for cluster of offshore WPPs connected to the same HVDC connection is being implemented and analyzed. The study is targeting two cases as; coordination of reactive power flow between HVDC converter and the WPP cluster while providing offshore AC grid voltage...... control, and coordinated closed loop control between the HVDC and the WPPs while the cluster is providing Power Oscillation Damping ( POD) via active power modulation. It is shown that the coordinated cluster control helps to improve the steady-state and dynamic response of the offshore AC grid in case...

  18. Coordination Control Strategy for Compound Fault of MMC-HVDC

    OpenAIRE

    Zhang Ming Guang; Zhang Zhao Yu; Qiu Li Jie; Chen Xi

    2016-01-01

    Single-line to ground fault of DC side and sub-module fault are typical faults of MMC-HVDC. When each of the above faults occurs, the system will give a signal for circuit-breaker releasing, this will result in interruption of power delivery, the stability of the system is greatly reduced. When these two faults occur simultaneously, research on control strategy for compound fault will help to improve the reliability of the system. While single-line to ground fault of DC side happens, only the...

  19. A Proposal on Low Frequency AC Transmission as a Multi-Terminal Transmission System

    Directory of Open Access Journals (Sweden)

    Achara Pichetjamroen

    2016-08-01

    Full Text Available This paper is focused on the discussion and comparison of characteristics and behavior of three low frequency ac (LFAC transmission system configurations operating under the same control scheme and conditions to identify the most promising operation system for LFAC. Merits of LFAC over high voltage direct current (HVDC are mentioned first. By changing power flow direction without auxiliary switches in multi-terminal application and easiness of short circuit protection are explained. The three configurations of LFACs are described and applied by the control scheme with the aid of the tool of the PSCAD/EMTDC software to consider the behavior of each LFAC system on line frequency and low frequency sides. For two-phase system, no fluctuation occurs on the line frequency side, which is the advantage over single-phase system. Furthermore, current rating on thyristor devices during operation and number of devices that used in each type of LFAC are calculated and compared. These results can lead to determine the most suitable transmission system for the LFAC system operation.

  20. Control Strategy of VSC-HVDC in Dual-infeed HVDC Systems%双馈入直流输电系统中VSC-HVDC的控制策略

    Institute of Scientific and Technical Information of China (English)

    赵成勇; 孙营; 李广凯

    2008-01-01

    针对多馈入直流输电(multi-infeed direct current,MIDC)系统的稳定性问题,提出将基于电压源换流器的高压直流输电(voltage source converter based HVDC,VSC-HVDC)引入到MIDC系统中,用以改善MIDC系统公共连接母线的电压特性.建立HVDC和VSC-HVDC双馈入系统的物理模型,导出相应的数学模型.并通过坐标变换得出VSC功率传输方程的直角坐标形式.采用多变量非线性控制的逆系统方法,设计VSC-HVDC系统的非线性控制器.PSCAD/EMTDC 环境下的仿真实验表明,所设计的VSC-HVDC非线性控制器不仅能有效改善VSC-HVDC的动态特性,而且在交流系统发生扰动时能有效稳定系统电压,减少HVDC逆变站发生换相失败的几率,提高HVDC系统的运行可靠性.

  1. Protection of ± 500 kV HVDC Double-circuit Converter Station from Lightning Induced Overvoltage

    Institute of Scientific and Technical Information of China (English)

    DONG Manling; YUAN Zhiyong; LI Tianwei; ZHAO Xiangen; ZHANG Jiaxin; HE Junjia

    2013-01-01

    In order to obtain reasonable schemes of arrester in converter stations,the arrester scheme of"Xiluodu-Guangdong HVDC ±500 kV double circuit transmission" project against lighting induced overvoltage,which was designed according to the main principle of lightning protection in converter station,is discussed.A calculation of the lighting induced overvoltage in Zhaotong converter station under various operation modes is performed with ATP-EMTP software,then the surge arrester configuration of the converter station is decided,and the arrester protection schemes of smoothing reactor and neutral line are studied.It is concluded that additional protection is necessary because of the relatively large gap between protected disconnecting switch and arrester of metallic return transfer bus.Plus,the smoothing reactor (SR) arrester near the valve hall could be removed to improve the scheme's economic performance.

  2. Synthesis of a hybrid model of the VSC FACTS devices and HVDC technologies

    Science.gov (United States)

    Borovikov, Yu S.; Gusev, A. S.; Sulaymanov, A. O.; Ufa, R. A.

    2014-10-01

    The motivation of the presented research is based on the need for development of new methods and tools for adequate simulation of FACTS devices and HVDC systems as part of real electric power systems (EPS). The Research object: An alternative hybrid approach for synthesizing VSC-FACTS and -HVDC hybrid model is proposed. The results: the VSC- FACTS and -HVDC hybrid model is designed in accordance with the presented concepts of hybrid simulation. The developed model allows us to carry out adequate simulation in real time of all the processes in HVDC, FACTS devices and EPS as a whole without any decomposition and limitation on their duration, and also use the developed tool for effective solution of a design, operational and research tasks of EPS containing such devices.

  3. Power-Hardware-In-the-Loop (PHIL) Test of VSC-based HVDC connection for Offshore Wind Power Plants (WPPs)

    DEFF Research Database (Denmark)

    Sharma, Ranjan; Cha, Seung-Tae; Wu, Qiuwei;

    2011-01-01

    This paper presents a power-hardware-in-the-loop (PHIL) test for an offshore wind power plant (WPP) interconnected to the onshore grid by a VSC-based HVDC connection. The intention of the PHIL test is to verify the control coordination between the plant side converter of the HVDC connection...... the successful control coordination between the WPP and the plant side VSC converter of the HVDC connection of the WPP....

  4. Transporte de energía eléctrica en corriente contínua. Enlaces HVDC-VSC

    OpenAIRE

    Monterrubio Díez, Mario

    2013-01-01

    El proyecto fin de carrera se plantea como un estudio de la tecnología HVDC-VSC, por su carácter novedoso y reciente implantación en los sistemas de transporte de electricidad. Con este trabajo se pretende dar a conocer de modo general la tecnología HVDC y de manera particular la variante HVDC-VSC.

  5. Power Flow Algorithms for Multi-Terminal VSC-HVDC With Droop Control

    OpenAIRE

    Wang, Wenyuan; Barnes, Mike

    2014-01-01

    This paper addresses the problem posed by complex, nonlinear controllers for power system load flows employing multi-terminal voltage source converter (VSC) HVDC systems. More realistic dc grid control strategies can thus be carefully considered in power flow analysis of ac/dc grids. Power flow methods for multi-terminal VSC-HVDC (MTDC) systems are analyzed for different types of dc voltage control techniques and the weaknesses of present methods are addressed. As distributed voltage control ...

  6. Marine High Voltage Power Conditioning and Transmission System with Integrated Storage DE-EE0003640 Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Frank Hoffmann, PhD; Aspinall, Rik

    2012-12-10

    Design, Development, and test of the three-port power converter for marine hydrokinetic power transmission. Converter provides ports for AC/DC conversion of hydrokinetic power, battery storage, and a low voltage to high voltage DC port for HVDC transmission to shore. The report covers the design, development, implementation, and testing of a prototype built by PPS.

  7. 交流系统故障时 VSC-HVDC 的保护策略研究

    Institute of Scientific and Technical Information of China (English)

    王帅

    2015-01-01

    本文分析了交流系统电压平衡时 VSC-HVDC 系统的控制策略,阐述了柔性直流输电系统的控制,SC-HVDC 系统的控制策略,内环电流控制器设计,VSC-HVDC 系统仿真与分析,指出交流系统故障时VSC-HVDC 系统的控制策略。

  8. Experimental Investigation of the Corona Discharge in Electrical Transmission due to AC/DC Electric Fields

    Directory of Open Access Journals (Sweden)

    Fuangpian Phanupong

    2016-01-01

    Full Text Available Nowadays, using of High Voltage Direct Current (HVDC transmission to maximize the transmission efficiency, bulk power transmission, connection of renewable power source from wind farm to the grid is of prime concern for the utility. However, due to the high electric field stress from Direct Current (DC line, the corona discharge can easily be occurred at the conductor surface leading to transmission loss. Therefore, the polarity effect of DC lines on corona inception and breakdown voltage should be investigated. In this work, the effect of DC polarity and Alternating Current (AC field stress on corona inception voltage and corona discharge is investigated on various test objects, such as High Voltage (HV needle, needle at ground plane, internal defect, surface discharge, underground cable without cable termination, cable termination with simulated defect and bare overhead conductor. The corona discharge is measured by partial discharge measurement device with high-frequency current transformer. Finally, the relationship between supply voltage and discharge intensity on each DC polarity and AC field stress can be successfully determined.

  9. Commutation circuit for an HVDC circuit breaker

    Science.gov (United States)

    Premerlani, William J.

    1981-01-01

    A commutation circuit for a high voltage DC circuit breaker incorporates a resistor capacitor combination and a charging circuit connected to the main breaker, such that a commutating capacitor is discharged in opposition to the load current to force the current in an arc after breaker opening to zero to facilitate arc interruption. In a particular embodiment, a normally open commutating circuit is connected across the contacts of a main DC circuit breaker to absorb the inductive system energy trapped by breaker opening and to limit recovery voltages to a level tolerable by the commutating circuit components.

  10. Possibility of a gas-cooled Peltier current lead in the 200 m-class superconducting direct current transmission and distribution system of CASER-2

    Science.gov (United States)

    Kawahara, Toshio; Emoto, Masahiko; Watanabe, Hirofumi; Hamabe, Makoto; Yamaguchi, Sataro; Hikichi, Yasuo; Minowa, Masahiro

    Global energy problems should be solved quickly, and superconducting applications are highly demanded as energy saving technologies. Among them, long-distance superconducting transmission seems to be one of the most promising for energy saving by energy sharing. On the other hand, such large systems can be constructed from smaller network systems that can be enhanced by scaling up to the superconducting grid. Reducing heat leak to the low temperature end is the most important aspect of technology for practical superconducting applications, and heat leak reduction at the terminal is a key goal especially for small-length applications. At Chubu University, we have developed a 200 m-class superconducting direct current transmission and distribution system (CASER-2), in which we also used a Peltier current lead (PCL) as heat insulation at the terminal. PCL is composed of a thermoelectric material and a copper lead. In actual transmission and distribution applications, the cables are also cooled by the coolant. After the circulation, the coolant could also be used to cool the current lead. We will discuss the performance of such gas-cooled systems as the total performance of applied superconducting systems using the experimental parameters obtained in CASER-2.

  11. Development of a HVDC prototype breaker

    Science.gov (United States)

    Damsky, B. L.; Barkan, P.; Imam, I.; Permerlani, W.; Anderson, J. M.; Carroll, J. J.; Hudson, J. E.; Pohl, R. V.; Solberg, W. D.; Sharbaugh, A. H.

    1980-06-01

    The design features of high voltage dc circuit breaker based on the commutation concept are studied. Tests of components indicate the breaker is capable of interrupting a fault current of 10 kA on a 400 kV system and absorbing up to 10 MJ of system energy without generating more than 1.6 per unit voltage on the system. Interactions of the breaker with a three terminal network were studied using a system simulator.

  12. Current Knowledge of Leishmania Vectors in Mexico: How Geographic Distributions of Species Relate to Transmission Areas

    Science.gov (United States)

    González, Camila; Rebollar-Téllez, Eduardo A.; Ibáñez-Bernal, Sergio; Becker-Fauser, Ingeborg; Martínez-Meyer, Enrique; Peterson, A. Townsend; Sánchez-Cordero, Víctor

    2011-01-01

    Leishmaniases are a group of vector-borne diseases with different clinical manifestations caused by parasites transmitted by sand fly vectors. In Mexico, the sand fly Lutzomyia olmeca olmeca is the only vector proven to transmit the parasite Leishmania mexicana to humans, which causes leishmaniasis. Other vector species with potential medical importance have been obtained, but their geographic distributions and relation to transmission areas have never been assessed. We modeled the ecological niches of nine sand fly species and projected niches to estimate potential distributions by using known occurrences, environmental coverages, and the algorithms GARP and Maxent. All vector species were distributed in areas with known recurrent transmission, except for Lu. diabolica, which appeared to be related only to areas of occasional transmission in northern Mexico. The distribution of Lu. o. olmeca does not overlap with all reported cutaneous leishmaniasis cases, suggesting that Lu. cruciata and Lu. shannoni are likely also involved as primary vectors in those areas. Our study provides useful information of potential risk areas of leishmaniasis transmission in Mexico. PMID:22049037

  13. Design of the ITER Electron Cyclotron Heating and Current Drive Waveguide Transmission Line

    Science.gov (United States)

    Bigelow, T. S.; Rasmussen, D. A.; Shapiro, M. A.; Sirigiri, J. R.; Temkin, R. J.; Grunloh, H.; Koliner, J.

    2007-11-01

    The ITER ECH transmission line system is designed to deliver the power, from twenty-four 1 MW 170 GHz gyrotrons and three 1 MW 127.5 GHz gyrotrons, to the equatorial and upper launchers. The performance requirements, initial design of components and layout between the gyrotrons and the launchers is underway. Similar 63.5 mm ID corrugated waveguide systems have been built and installed on several fusion experiments; however, none have operated at the high frequency and long-pulse required for ITER. Prototype components are being tested at low power to estimate ohmic and mode conversion losses. In order to develop and qualify the ITER components prior to procurement of the full set of 24 transmission lines, a 170 GHz high power test of a complete prototype transmission line is planned. Testing of the transmission line at 1-2 MW can be performed with a modest power (˜0.5 MW) tube with a low loss (10-20%) resonant ring configuration. A 140 GHz long pulse, 400 kW gyrotron will be used in the initial tests and a 170 GHz gyrotron will be used when it becomes available. Oak Ridge National Laboratory, managed by UT-Battelle, LLC, for the U.S. Dept. of Energy under contract DE-AC05-00OR22725.

  14. Transcutaneous communication system using the human body as conductive medium: influence of transmission data current on the heart.

    Science.gov (United States)

    Okamoto, Eiji; Kikuchi, Sakiko; Miura, Hidekazu; Shiraishi, Yasuyuki; Yambe, Tomoyuki; Mitamura, Yoshinori

    2013-01-01

    We developed a new transcutaneous communication system (TCS) that uses the human body as a conductive medium for monitoring and controlling artificial hearts and other artificial organs in the body.In this study, the physiological effect of data current discharged into the body during data transmission was evaluated by an animal experiment using a goat. The external and internal units of the new TCS each mainly consist of a data transmitter and a data receiver. The data transmitter has an amplitude shift keying (ASK) modulator (carrier frequencies: 4 and 10 MHz) and an electrode.The internal unit of the TCS was fixed on the pericardium and the external unit was placed on the left ear, and each transmitter discharged an ASK-modulated current of 7 mA (RMS) into the conscious goat. The TCS was able to transmit data for 4 weeks under full duplex communication with a transmission rate of 115 kbps. On the 28th postoperative day, an electrocardiogram was measured during data transmission. Cardiac rhythm and waveform of the electrocardiogram were not changed before and during bidirectional data transmission. Also, no adverse effect on the heart was observed by autopsy.

  15. Study of the dynamics of the electrode plasma in a high-current magnetically insulated transmission line

    Science.gov (United States)

    Bakshaev, Yu. L.; Bartov, A. V.; Blinov, P. I.; Chernenko, A. S.; Dan'ko, S. A.; Kalinin, Yu. G.; Kingsep, A. S.; Korolev, V. D.; Mizhiritskiĭ, V. I.; Smirnov, V. P.; Shashkov, A. Yu.; Sasorov, P. V.; Tkachenko, S. I.

    2007-04-01

    A series of experiments was carried out in the S-300 facility (3 MA, 0.15 Θ, 100 ns) to study the behavior of a section of a magnetically insulated transmission line (MITL) at current densities of up to 500 MA/cm2 and linear current densities of up to 6 MA/cm (i.e., at parameters close to those expected in a fast Z-pinch fusion reactor projected in Sandia National Laboratories). The surface explosion of the ohmically heated MITL electrode is accompanied by the formation of a plasma layer on its surface. This can deteriorate of the transmission properties of the line because the vacuum gap is short-circuited by the plasma produced. The parameters of the electrode plasma and its effect on the MITL transmission properties were investigated experimentally. Possible consequences of the above effects are evaluated, and MHD simulations of the electrode explosion and the subsequent spread of the plasma layer are performed. It is shown that the time during which an MITL segment preserves its transmission properties conforms to the requirements of the conceptual fusion reactor.

  16. AC Voltage Control of DC/DC Converters Based on Modular Multilevel Converters in Multi-Terminal High-Voltage Direct Current Transmission Systems

    Directory of Open Access Journals (Sweden)

    Rui Li

    2016-12-01

    Full Text Available The AC voltage control of a DC/DC converter based on the modular multilevel converter (MMC is considered under normal operation and during a local DC fault. By actively setting the AC voltage according to the two DC voltages of the DC/DC converter, the modulation index can be near unity, and the DC voltage is effectively utilized to output higher AC voltage. This significantly decreases submodule (SM capacitance and conduction losses of the DC/DC converter, yielding reduced capital cost, volume, and higher efficiency. Additionally, the AC voltage is limited in the controllable range of both the MMCs in the DC/DC converter; thus, over-modulation and uncontrolled currents are actively avoided. The AC voltage control of the DC/DC converter during local DC faults, i.e., standby operation, is also proposed, where only the MMC connected on the faulty cable is blocked, while the other MMC remains operational with zero AC voltage output. Thus, the capacitor voltages can be regulated at the rated value and the decrease of the SM capacitor voltages after the blocking of the DC/DC converter is avoided. Moreover, the fault can still be isolated as quickly as the conventional approach, where both MMCs are blocked and the DC/DC converter is not exposed to the risk of overcurrent. The proposed AC voltage control strategy is assessed in a three-terminal high-voltage direct current (HVDC system incorporating a DC/DC converter, and the simulation results confirm its feasibility.

  17. 大型海上风电场并网VSC-HVDC变流器关键技术%Key Technologies of Large Offshore Wind Farm VSC-HVDC Converters for Grid Integration

    Institute of Scientific and Technical Information of China (English)

    王志新; 吴杰; 徐烈; 王国强

    2013-01-01

    In recent years, offshore wind energy has been developing rapidly because of many advantages, e.g. not taking up land resources, high utilization rate and so on. By 2011, the global total installed capacity of offshore wind power was 4 954 MW, with 241.3 MW in China. And the planning capacity in China would be 5 GW by 2015 and 30 GW by 2020. Large-scale development and utilization of offshore wind farms increase the requirements for converters of VSC direct current transmission, such as converter topology and control method, and their applications to offshore wind farms. Key technologies of large offshore wind farm VSC-HVDC converter involve detailed multilevel converter topology, modulation, voltage balancing strategies and offshore wind farm modeling techniques etc. These can provide theoretical foundation for the grid integration of large offshore wind farms, and there is academic significance and practical value for improving the utilization and large-scale development of offshore wind power.%  近年来,海上风电因具有不占用陆上土地资源、风能利用率高等诸多优势,得到了迅速发展。截至2011年底,全球已建成80个海上风电场,累计装机容量达到4954 MW。其中,我国2011年海上风电累计总装机为241.3 MW。此外,我国还规划到2015年和2020年,我国海上风电总装机将分别累计达到5和30 GW。随着海上风电的规模化开发与利用量的巨大增长,海上风电场并网柔性直流输电系统(voltage source converter based high-voltage direct current , VSC-HVDC)的应用也为业界所关注,并对海上风电柔性直流输电变流器提出了更高的要求。大型海上风电场并网VSC-HVDC 的关键技术主要涉及变流器拓扑结构和控制方法,以及在海上风电场中的应用等,例如海上风电柔性直流输电变流器的多电平拓扑结构、调制方法、均压控制策略以及海上风电场建模等关键技术。分析、总

  18. Improvement of Wind Energy Production through HVDC Systems

    Directory of Open Access Journals (Sweden)

    Morris Brenna

    2017-01-01

    Full Text Available Variable and non-programmable resources, such as solar and wind, have undergone a stunning growth in recent years and are likely to gain even more importance in the future. Their strong presence in the national electricity mix has created issues in many countries regarding the secure operation of the power system. In order to guarantee the stability of the system, several TSOs have resorted to wind energy curtailment, which represents a waste of clean energy and an economic loss. In order to analyze this issue, a model of the Italian power system was developed, a program able to simulate the electricity dispatching mechanism. The model was, then, used to evaluate possible solutions to reduce wind curtailment. In particular, a proposal for the construction of an HVDC line linking Southern and Northern Italy was studied.

  19. Analysis of operations and cyber security policies for a system of cooperating Flexible Alternating Current Transmission System (FACTS) devices.

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, Laurence R.; Tejani, Bankim; Margulies, Jonathan; Hills, Jason L.; Richardson, Bryan T.; Baca, Micheal J.; Weiland, Laura

    2005-12-01

    Flexible Alternating Current Transmission Systems (FACTS) devices are installed on electric power transmission lines to stabilize and regulate power flow. Power lines protected by FACTS devices can increase power flow and better respond to contingencies. The University of Missouri Rolla (UMR) is currently working on a multi-year project to examine the potential use of multiple FACTS devices distributed over a large power system region in a cooperative arrangement in which the FACTS devices work together to optimize and stabilize the regional power system. The report describes operational and security challenges that need to be addressed to employ FACTS devices in this way and recommends references, processes, technologies, and policies to address these challenges.

  20. Current dependence of heat leak on the terminals in the superconducting DC transmission and distribution system of CASER-2

    Science.gov (United States)

    Kawahara, Toshio; Watanabe, Hirofumi; Emoto, Masahiko; Hamabe, Makoto; Yamaguchi, Sataro; Hikichi, Yasuo; Minowa, Masahiro

    2012-12-01

    Superconductivity can solve the energy problems in the world as energy saving technologies. In particular, superconducting direct current (DC) transmission and distribution (T&D) systems is promising, as it can be easily extended to large scale energy transmission systems for energy sharing. We are developing criogenic systems for effective cooling of superconducting T&D systems. In the cooling experiments with the 200 m-class superconducting DC T&D system at Chubu University (CASER-2), we have estimated the performance of the system. For example, our superconducting cable is connected to the outside at the terminals using Peltier current leads (PCLs). The PCL is composed of a thermoelectric material and a copper lead. Small thermal conductivity and large thermopower of the thermoelectric modules can effectively insulate the heat leak to the low temperature end. We measured the temperature along the current leads and the heat leak at the terminals. As current leads have an optimal shape factor, the optimum operation current exists. The current dependence of the system performance is discussed.

  1. Modeling and Control of High-Voltage Direct-Current Transmission Systems: From Theory to Practice and Back

    OpenAIRE

    2014-01-01

    The problem of modeling and control of multi-terminal high-voltage direct-current transmission systems is addressed in this paper, which contains five main contributions. First, to propose a unified, physically motivated, modeling framework - based on port-Hamiltonian representations - of the various network topologies used in this application. Second, to prove that the system can be globally asymptotically stabilized with a decentralized PI control, that exploits its passivity properties. Cl...

  2. Operation and control of a DC-grid offshore wind farm under DC transmission system faults

    DEFF Research Database (Denmark)

    Deng, Fujin; Chen, Zhe

    2013-01-01

    So far, all existing offshore wind farms have an ac collection system, and the collected power in the offshore wind farm is sent to an onshore ac grid through high-voltage ac (HVAC) or DC (HVDC) transmission lines. However, future of fshore wind farms may use dc also for power collection. Consequ...

  3. Current Concepts for the IND-Directed Development of Microbicide Products to Prevent the Sexual Transmission of HIV.

    Science.gov (United States)

    Buckheit, Karen W; Furlan-Freguia, Christian; Ham, Anthony S; Buckheit, Robert W

    2016-01-01

    In the absence of an approved and effective vaccine, topical microbicides have become the strategy of choice to provide women with the ability to prevent the sexual transmission of HIV. Topical microbicides are chemical and physical agents specifically developed and formulated for use in either the vaginal or rectal environment to prevent the sexual transmission of infectious organisms. Although a microbicide product will have many of the same properties as other anti-infective therapeutic agents, the microbicide development pathway has significant differences which reflect the complex biological environment in which the products must act. These challenges to the development of an effective microbicide are reflected in the recently released FDA Guidance document which defines the microbicide development algorithm and includes the evaluation of preclinical efficacy and toxicity, and safety and toxicology, and indicates the necessity of testing of the active pharmaceutical product as well as an optimal formulation for delivery of the microbicide product. The microbicide development algorithm requires evaluation of the potential microbicidal agent and final formulated product in assays which mimic the microenvironment of the vagina and rectum during the sexual transmission of HIV, including the evaluation of activity and cytotoxicity in the appropriate biological matrices, toxicity testing against normal vaginal flora and at standard vaginal pH, testing in ectocervical and colorectal explant tissue, and irritation studies to vaginal, rectal and penile tissue. Herein, we discuss currently accepted practices required for the development of a successful microbicide product which will prevent virus transmission in the vaginal and rectal vaults.

  4. Multilink DC Transmission for Offshore Wind Power Integration

    DEFF Research Database (Denmark)

    Craciun, Bogdan-Ionut; Silva, Rodrigo Da; Teodorescu, Remus;

    2012-01-01

    The High Voltage Direct Current (HVDC) system gains much more flexibility on a basis of multi terminal operation. Having extra converters brings also new ideas in sharing the active power and one of the solutions is the use of virtual impedance correlated with a droop controller. This paper analy...

  5. Measurement and interpretation of current transmission in a crossed-field diode below cutoff

    Energy Technology Data Exchange (ETDEWEB)

    Vanderberg, B.H.; Eninger, J.E. [Department of Industrial Electrotechnology, Royal Institute of Technology, S-100 44 Stockholm (Sweden)

    1997-02-01

    Measurements on the current-voltage-magnetic field characteristics of a space-charge-limited cylindrical cross-field diode below cutoff are presented. The measured current is found to be lower than predicted by simple cold-fluid theory. This reduction combined with observed oscillations in the current can be explained by secondary electron emission from the anode, leading to an increase of space charge in the diode. {copyright} {ital 1997 American Institute of Physics.}

  6. Coordinated control of multiple HVDC links using input-output exact linearization

    Energy Technology Data Exchange (ETDEWEB)

    Eriksson, Robert; Knazkins, Valerijs; Soeder, Lennart [Royal Institute of Technology (KTH), Electric Power Systems, Teknikringen 33, 100 44 Stockholm (Sweden)

    2010-12-15

    This paper is concerned with the investigation of a new control technique for the conventional High Voltage Direct Current (HVDC) link. The proposed technique relies upon nonlinear state feedback linearization of the AC/DC power system. The idea in input-output exact feedback linearization is to algebraically transform nonlinear systems dynamics into a linear control problem using a nonlinear pre-feedback loop, and then for the linearized power system one can design another feedback loop using a well established technique such as a linear-quadratic regulator. The primary goal of the controller presented in this paper is to contribute to the enhancement of both the transient and the small-signal stability of the power system. Since the proposed state feedback linearization does not rely on the assumption that there is only small deviation of the states from an equilibrium, the enhancement of both is feasible. The simulation results obtained in the framework of the study show that the proposed controller is capable of stabilizing the system in various system operating conditions. (author)

  7. 特高压直流输电线路等效干扰电流的计算以及影响因素的研究%Computation of Equivalent Disturbing Current in UHVDC Power Transmission Lines and Analysis on Its Influencing Factors

    Institute of Scientific and Technical Information of China (English)

    赵鹏

    2012-01-01

    高压直流输电工程中,常以等效干扰电流作为限制直流谐波水平的标准.为了计算出准确的等效干扰电流,利用3脉动模型,对特高压直流输电工程进行了建模,计算了不同的直流滤波系统参数的等效干扰电流,得出了等效干扰电流随直流滤波系统中各部分参数变化的规律,即:等效干扰电流随平波电抗器电感值的增大而减小,随中性线接地电容的增大而减小,随直流滤波器高压电容值的增加而减小,并分别得出了变化规律曲线;文中还给出了使等效干扰电流满足允许值要求的滤波系统参数.%Equivalent disturbing current is used as the standard of restricting harmonic current level at DC side in HVDC project. To compute accurate equivalent disturbing current, using 3-pulse model the UHVDC power transmission project was modeled and equivalent disturbing currents under different parameters of DC filtering system were calculated, thus following rules of equivalent disturbing current varying with parameters of component parameters were attained: the equivalent disturbing current decreases with the increase of inductance value of smoothing reactor; it decreases with the increase of neutral-line-to ground capacitance; it decreases with the increase of capacity of HV capacitor of DC filter, and corresponding varying curves were obtained. Besides, the parameters of the filtering system, by which the equivalent disturbing current could meet the requirement of the allowable value, were proposed.

  8. Voltage Stability Bifurcation Analysis for AC/DC Systems with VSC-HVDC

    Directory of Open Access Journals (Sweden)

    Yanfang Wei

    2013-01-01

    Full Text Available A voltage stability bifurcation analysis approach for modeling AC/DC systems with VSC-HVDC is presented. The steady power model and control modes of VSC-HVDC are briefly presented firstly. Based on the steady model of VSC-HVDC, a new improved sequential iterative power flow algorithm is proposed. Then, by use of continuation power flow algorithm with the new sequential method, the voltage stability bifurcation of the system is discussed. The trace of the P-V curves and the computation of the saddle node bifurcation point of the system can be obtained. At last, the modified IEEE test systems are adopted to illustrate the effectiveness of the proposed method.

  9. Fault Characteristics and Control Strategies of Multiterminal High Voltage Direct Current Transmission Based on Modular Multilevel Converter

    Directory of Open Access Journals (Sweden)

    Fei Chang

    2015-01-01

    Full Text Available The modular multilevel converter (MMC is an emerging voltage source converter topology suitable for multiterminal high voltage direct current transmission based on modular multilevel converter (MMC-MTDC. This paper presents fault characteristics of MMC-MTDC including submodule fault, DC line fault, and fault ride-through of wind farm integration. Meanwhile, the corresponding protection strategies are proposed. The correctness and effectiveness of the control strategies are verified by establishing a three-terminal MMC-MTDC system under the PSCAD/EMTDC electromagnetic transient simulation environment.

  10. 78 FR 54876 - Amended Notice of Intent To Modify the Scope of the Environmental Impact Statement and Conduct...

    Science.gov (United States)

    2013-09-06

    ... construct, operate, maintain, and connect a high-voltage direct current (HVDC) transmission line across the... Pass proposes to construct and operate a primarily overhead HVDC electric transmission line that would originate at an HVDC converter station to be constructed at the Des Cantons Substation in Qu bec,...

  11. Current trends in the application of non-ceramic insulators for transmission & distribution lines subject to contamination

    Energy Technology Data Exchange (ETDEWEB)

    Riordan, K.C. [Reliable Power Products, Franklin Park, IL (United States)

    1994-12-31

    Non-Ceramic Insulators (NCI) have been in application for more than 25 years. During this time, manufacturers have worked diligently to improve product designs and polymer materials. Today, the use of Non-Ceramic Polymer insulators is proliferating as Utilities become more confident in this advanced technology. The application advantages of NCI technology are more widely recognized and understood and credibility is growing in the long term service performance of these insulators. Current estimates place the NCI market share as high as 50% of the total US transmission insulator market. Indeed, Reliable Power Products is proud to advise that their insulators have been selected for the first 500 KV-DC transmission line in the USA to use 100% composite polymer insulators. With the combination of Los Angeles Department of Water and Power (Los Angeles to Las Vegas) and Salt River Project (Las Vegas to Phoenix), a total of almost 1,000 Kms. of transmission line will be insulated with Silicone Rubber Polymer Insulators. The total project will include almost 15,000 insulator strings. User confidence is not confined to the USA market. The application of NCI`s by International Utilities has also experienced significant growth. This may be evidenced by EHV installations in South America, Middle East, South Africa, Australia and South East Asia.

  12. Online fault location on AC cables in underground transmission systems using screen currents

    DEFF Research Database (Denmark)

    Jensen, Christian Flytkjær; Nanayakkara, O.M.K.K; Rajapakse, Athula

    This paper studies online travelling wave methods for fault location on a crossbonded cable system using screen currents. During the construction of the electrical connection to the 400 MW off shore wind farm Anholt, it was possible to perform measurements on a 38.4 km crossbonded cable system...... coils if the screen currents contain the necessary information for accurate fault location. In this paper, this is examined by analysis of field measurements and through a study of simulations. The wavelet transform and visual inspection methods are used and the accuracy is compared. Field measurements...... and simulations are compared for testing the reliability of using simulations for studying fault location methods....

  13. 低电平MMC-HVDC样机滤波装置设计%Design of Filtering Device for Low Level Prototype of MMC-HVDC

    Institute of Scientific and Technical Information of China (English)

    王卫安; 桂卫华

    2011-01-01

    为了确保低电平模块化多电平换流器直流输电(MMC-HVDC)样机注入公共电网的谐波含量符合现有的电能质量标准条例,对其进行配套的滤波装置设计是必要的.文章根据MMC拓扑结构特点,推导出了MMC的等值电路,并将MMC看成一个有多种谐波的谐波电压源,从而设计了MMC交流侧谐波的等效电路.在此基础上,结合MMC-HVDC的调制策略,设计出了与样机配套的滤波装置,仿真结果表明了其滤波装置设计方法的正确性.%In order to ensure the harmonic of common electric network injected by low level prototype of modular multilevel converter high voltage direct current (MMC-HVDC) could accord with existing electric power quality standard regulations, it is necessary to design filtering devices for the prototype. According to the topology structure of MMC, an equivalent circuit was deduced, and regarding MMC as one harmonic source con-tairfing multiform harmonics, the equivalent circuit which could calculate the harmonic at AC side of MMC was obtained. Based on above, and combined with modulation strategy of MMC-HVDC, the filters for the prototype were designed. Simulation results show the method to design the filtering devices is correct.

  14. Online Fault Location on AC Cables in Underground Transmission Systems using Sheath Currents

    DEFF Research Database (Denmark)

    Jensen, Christian Flytkjær; Nanayakkarab, Kasun; Rajapakse, Athula

    2014-01-01

    This paper studies online travelling wave methods for fault location on a crossbonded cable system using sheath currents. During the construction of the electrical connection to the 400 MW off shore wind farm Anholt, it was possible to perform measurements on a 38.4 km crossbonded cable system. A...

  15. Online fault location on AC cables in underground transmission systems using screen currents

    DEFF Research Database (Denmark)

    Jensen, Christian Flytkjær; Nanayakkara, O.M.K.K; Rajapakse, Athula

    This paper studies online travelling wave methods for fault location on a crossbonded cable system using screen currents. During the construction of the electrical connection to the 400 MW off shore wind farm Anholt, it was possible to perform measurements on a 38.4 km crossbonded cable system. A...

  16. Distribution of zero sequence currents for earth faults occurring along a transmission line and proximity effects

    Energy Technology Data Exchange (ETDEWEB)

    Nahman, J. (Belgrade Univ. (Yugoslavia). Elektrotehnicki Fakultet); Dordevic, V. (Energoprojekt, Belgrade (Yugoslavia))

    1993-09-01

    A relatively simple procedure is suggested for the evaluation of the distribution of zero sequence currents, within the earthing system of a substation, for earth faults occurred along a line coming from the substation. The earthing system model derived takes into account all relevant phenomena including the mutual influence among earth electrodes through the soil to cover the proximity effects which were shown to be significant in certain cases. The procedure suggested is applied to a practical case, for illustration. (author)

  17. Coupling and corona effects research plan for transmission lines. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Bridges, J E; Formanek, V C

    1976-06-01

    Concern has arisen over the possible effects of electric and magnetic fields produced by EHV-UHV transmission lines. Past and ongoing research concerning the electric and magnetic field effects from EHV-UHV transmission lines was reviewed as it pertains to the following areas: (1) electromagnetic interference, (2) acoustic noise, (3) generation of gaseous effluents, and (4) safety considerations of induced voltages and currents. The intent of this review was to identify the short and long range research projects required to address these areas. The research plan identifies and gives priority to twenty programs in corona and coupling effects. In the case of the corona effects, a number of programs were recommended for acoustic noise and electromagnetic interference to delineate improved power line design criteria in terms of social, meteorological, geographical and cost constraints. Only one project is recommended in the case of ozone generation, because the results of comprehensive analyses, laboratory studies and field measurements have demonstrated that power lines do not contribute significant quantities of ozone. In the case of the coupling effects, a number of programs are recommended for HVAC transmission lines to improve the theoretically developed design guidelines by considering practical constraints. For HVDC transmission lines, programs are suggested to engender a better theoretical understanding and practical measurements capability for the coupling mechanisms of the dc electric and magnetic field with nearby objects. The interrelationship of the programs and their role in a long-term research plan is also discussed.

  18. Sea Breeze Juan de Fuca transmission project : combined interconnect impact and facility study : summary report

    Energy Technology Data Exchange (ETDEWEB)

    Morissette, V.; Azar, R. [SNC Lavalin Transmission and Distribution, Burnaby, BC (Canada)

    2009-05-08

    The Juan de Fuca (JDF) cable is a 550 MW High Voltage Direct Current (HVDC) submarine transmission line that will link Port Angeles, in Washington State, to South Vancouver Island. The objective of this combined interconnection impact and facility study is to determine the impact of this interconnection to the BC Transmission Corporation (BCTC) system in early 2010, specifically on Vancouver Island. The study involved the following tasks: load flow study; transient stability study; EMTP study; harmonic impedance analysis; insulation coordination study; evaluation of remedial action schemes (RAS); interconnection impact study report; and facility project plan study. The steady state and dynamic performance of the BCTC system on central Vancouver Island were assessed based on both normal operation and the predefined contingency conditions. Three load condition cases were considered, notably heavy winter 2010, light summer 2010 and light summer 2011. Cost estimates were provided along with lead times for the construction of transmission, station, protection and control, and telecom facilities and their auxiliary systems. It was concluded that the JDF cable will complement the existing grid and will add needed reliability, capacity and flexibility to transmission operations in the region. The JDF cable will strengthen British Columbia's electrical reliability and will meet Vancouver Island's electricity needs. According to the study, the cable will not result in any considerable steady state problems under both normal and contingency conditions. refs., tabs., figs.

  19. Real-time transmission Mueller polarimetry on hydrogenated polymorphous silicon under current injection

    Science.gov (United States)

    Kim, Ka-Hyun; Haj Ibrahim, Bicher; Johnson, Erik V.; De Martino, Antonello; Cabarrocas, Pere Roca i.

    2013-01-01

    We report on the use of an innovative optical characterization technique—real-time Mueller polarimetric imaging in transmission—for the characterization of thin-film silicon solar cells. In this work, we used this technique to monitor the evolution of optical retardance induced by the mechanical stresses in hydrogenated amorphous and polymorphous silicon (a-Si : H and pm-Si : H) p-i-n (PIN) solar cells. Under current injection of 200 mA cm-2, the retardance of the pm-Si : H PIN solar cells decreased, while that of the a-Si : H PIN solar cells showed no significant change. After the current injection, the pm-Si : H PIN solar cells showed dramatic macroscopic changes on a scale of tens of micrometres, such as local peel-off and delamination from the substrate. Our results demonstrate that current injection introduces local stress relaxation, which can be efficiently monitored prior to irreversible damage from a decrease in the retardance of the pm-Si : H PIN solar cells.

  20. In situ transmission electron microscopy investigation of the structural changes in carbon nanotubes during electron emission at high currents

    Energy Technology Data Exchange (ETDEWEB)

    Doytcheva, Maya [Philips Research, Professor Holstlaan 4, 5656 AA Eindhovene (Netherlands); Kaiser, Monja [Philips Research, Professor Holstlaan 4, 5656 AA Eindhoven (Netherlands); Jonge, Niels de [Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN 37831-6030 (United States)

    2006-07-14

    The structural changes in carbon nanotubes under electron emission conditions were investigated in situ in a transmission electron microscope (TEM). The measurements were performed on individually mounted free-standing multi-walled carbon nanotubes (CNTs). It was found that the structure of the carbon nanotubes did not change gradually, as is the case with field emission electron sources made of sharp metal tips. Instead, changes occurred only above a current level of a few microamperes, which was different for each nanotube. Above the threshold current, carbon nanotubes underwent either structural damage, such as shortening and splitting of the apex of the nanotube, or closing of their open cap. The results are discussed on the basis of several models for degradation mechanisms.

  1. In situ Transmission Electron Microscopy Investigation of the Structural Changes in Carbon Nanotubes During Electron Emission at High Currents

    Energy Technology Data Exchange (ETDEWEB)

    Doytcheva, Maya [Philips Research, The Netherlands; Kaiser, Monja [Philips Research, The Netherlands; De Jonge, Niels [ORNL

    2006-01-01

    The structural changes in carbon nanotubes under electron emission conditions were investigated in situ in a transmission electron microscope (TEM). The measurements were performed on individually mounted free-standing multi-walled carbon nanotubes (CNTs). It was found that the structure of the carbon nanotubes did not change gradually, as is the case with field emission electron sources made of sharp metal tips. Instead, changes occurred only above a current level of a few microamperes, which was different for each nanotube. Above the threshold current, carbon nanotubes underwent either structural damage, such as shortening and splitting of the apex of the nanotube, or closing of their open cap. The results are discussed on the basis of several models for degradation mechanisms.

  2. Distance protection of multiple-circuit shared tower transmission lines with different voltages. Part I: Fault current magnitude

    DEFF Research Database (Denmark)

    Silva, Filipe Miguel Faria da; Bak, Claus Leth

    2017-01-01

    Multiple-circuit transmission lines combining different voltage levels in one tower present extra challenges when setting a protection philosophy, as faults between voltage levels are possible. This paper presents a detailed theoretical analysis of such combined faults, including the development...... of a formula for estimating the magnitude of the short-circuit current. It is demonstrated that if the faulted phase from the higher voltage level leads the faulted phase from the lower voltage level, a distance relay at the higher voltage level sees the fault in the forward direction, whereas a distance relay...... at the lower voltage level sees the fault in the reverse direction. The opposite happens if the lower voltage level leads the higher voltage level. It is also demonstrated that the magnitude of fault currents of combined faults is normally slightly larger than of equivalent single-phase-to-ground fault...

  3. Control Strategy and Experimental Study of Hybrid HVDC Circuit Breaker%混合式高压直流断路器的控制策略与实验研究

    Institute of Scientific and Technical Information of China (English)

    杜翼; 江道灼; 陈可; 王玉芬; 尹瑞; 张弛

    2014-01-01

    现有的高压直流断路器能够在几十ms内断开电路,但对于高压直流输电系统,远不能达到要求。基于半导体的高压直流断路器能克服动作速度上的问题,但需要大量电力电子开关器件串并联,有很高的技术难度,同时会产生大量损耗。为了克服上述缺点,采用一种混合式高压直流断路器的拓扑结构。首先介绍了断路器开通和关断的原理,接着提出一种故障预处理的控制策略,在故障发生时提前进行换流,从而缩短故障发生后线路开断的时间;最后利用PSCAD进行建模仿真,制作了单元样机进行降压实验。仿真和实验结果证明:在系统发生短路的情况下,混合式直流断路器能够快速开断短路电流,还可以在直流线路分断后为直流线路及负载中储存的能量提供释放回路。%Existing HVDC circuit breakers are capable of interrupting HVDC currents within several tens of milliseconds, but this is too slow to fulfill the requirements of a reliable HVDC grid.HVDC breakers based on semiconductors can easily overcome the limitations of operating speed,but need large number of the series (parallel ) connection of electronic switching devices;at the same time, it requires high technology and generates a lot of loss. To overcome these shortcomings,a topology of hybrid HVDC circuit breaker was introduced.Firstly,this paper described the principle of hybrid HVDC circuit breaker;then a control strategy of fault pretreatment was also proposed,that was the pre-action of the converter when fault occurred,in order to improve the breaking speed of the hybrid circuit breaker;at last the modeling and simulation were carried out on the hybrid HVDC circuit breaker by PSCAD,and unit prototype was made for the step-down experiments.The simulation and experimental results prove that:when a short circuit occurs,the hybrid HVDC circuit breaker can quickly break the short-circuit current

  4. Localização de faltas em linhas de transmissão em corrente contínua segmentadas

    Directory of Open Access Journals (Sweden)

    Eduardo Gonzaga Silveira

    2013-11-01

    Full Text Available Este trabalho apresenta uma técnica para a localização de faltas em sistemas de transmissão High Voltage Direct Current (HVDC constituídos por linhas aéreas e cabos isolados. O método foi baseado na coleta de dados de dois terminais nas extremidades do elo de corrente contínua e pela detecção de faltas através de coeficientes da Transformada Wavelet Discreta tipo Haar. A partir do problema proposto, foi simulado com o auxílio do Alternative Transient Program (ATP, um sistema de transmissão em corrente contínua monopolar com conversores a tiristor Current Source Converter (CSC, constituído de duas linhas aéreas de 150 km e 80 km, e um segmento intermediário de cabo subterrâneo com 80 km. Os dados das respostas transitórias de curtos-circuitos em diferentes segmentos do elo foram carregados em uma interface gráfica criada no Matrix Laboratory (MATLAB, para realizar as rotinas de pré-processamento, além de detectar e localizar a falta. O método foi testado para diferentes taxas de amostragem e impedâncias de falta, ele apresentou resultados satisfatórios na localização de faltas em todos os segmentos da linha, com erros em torno de 0,5% do comprimento total do elo, além do baixo custo computacional, o que mostra a viabilidade de sua implementação prática.Palavras-chave: HVDC. Localização de faltas. ATP. Transformada Wavelet.Location of faults in transmission lines in continuous segmented streamAbstractThis paper presents a technique for location of faults in High Voltage Direct Current (HVDC transmission systems constituted of overhead lines and cables. The method was based on data collection of two terminals on the extremity of the continuous stream link, and through the fault detection using the Discrete Wavelet Transform coefficients of Haar type. From the proposed problem, it was simulated, with the support of the Alternative Transient Program (ATP, a transmission system in monopolar continuous stream with

  5. Risk factors for secondary transmission of Shigella infection within households: implications for current prevention policy

    Directory of Open Access Journals (Sweden)

    Boveé Lian

    2012-12-01

    Full Text Available Abstract Background Internationally, guidelines to prevent secondary transmission of Shigella infection vary widely. Cases, their contacts with diarrhoea, and those in certain occupational groups are frequently excluded from work, school, or daycare. In the Netherlands, all contacts attending pre-school (age 0–3 and junior classes in primary school (age 4–5, irrespective of symptoms, are also excluded pending microbiological clearance. We identified risk factors for secondary Shigella infection (SSI within households and evaluated infection control policy in this regard. Methods This retrospective cohort study of households where a laboratory confirmed Shigella case was reported in Amsterdam (2002–2009 included all households at high risk for SSI (i.e. any household member under 16 years. Cases were classified as primary, co-primary or SSIs. Using univariable and multivariable binomial regression with clustered robust standard errors to account for household clustering, we examined case and contact factors (Shigella serotype, ethnicity, age, sex, household size, symptoms associated with SSI in contacts within households. Results SSI occurred in 25/ 337 contacts (7.4%: 20% were asymptomatic, 68% were female, and median age was 14 years (IQR: 4–38. In a multivariable model adjusted for case and household factors, only diarrhoea in contacts was associated with SSI (IRR 8.0, 95% CI:2.7-23.8. In a second model, factors predictive of SSI in contacts were the age of case (0–3 years (IRRcase≥6 years:2.5, 95% CI:1.1-5.5 and 4–5 years (IRRcase≥6 years:2.2, 95% CI:1.1-4.3 and household size (>6 persons (IRR2-4 persons 3.4, 95% CI:1.2-9.5. Conclusions To identify symptomatic and asymptomatic SSI, faecal screening should be targeted at all household contacts of preschool cases (0–3 years and cases attending junior class in primary school (4–5 years and any household contact with diarrhoea. If screening was limited to these groups, only

  6. Study on Optical Fiber Drive and Detection Strategy in HVDC Light%轻型高压直流输电中的光纤驱动及检测策略

    Institute of Scientific and Technical Information of China (English)

    赵鹏; 肖岚

    2011-01-01

    非并网风电最主要的应用前景为具有直流负载特性的高耗能产业。非常适合于轻型高压直流输电(HVDCLight)。HVDCLight中,增加传输信号的抗电磁干扰能力,提高信号的速度和精度是当前研究的热点。为了将变换器的功率电路地与控制电路地进行电气隔离,使电源安全稳定地工作,设计了基于高压环境的光纤隔离驱动策略和光纤隔离检测策略。为了满足高压信号实时检测的需要,采用“V/F转换-光纤传输-F/v转换”方式进行转换、传输和检测;为了满足高压驱动的需要,采用M57962AL结合光纤来实现。实验验证了该方案的可行性。它具有隔离电压等级高、传输精度高、速度快等优点。%The non-grid-connection wind power is mainly used in high energy consumption industries with DC load, especially in the High Voltage Direct Current Light (HVDC Light), where advancing the transmission capabiliW of anti-electromagnetic and improving the speed and accuracy are one of the hot spots of current researches. The fiber-optical isolation drive and fiber-optical detection strategy in high voltage environment are put forward, which are proposed through making electrical isolation between power supply from the ground of converter circuit and control circuit to finally ensure the stable and safe work of power supply. On the one hand, the method of "the V/F transform-fiber optical transmission-F/V transform" to convert, transmit and detect signals is used to realize any specific detection of the high voltage signal. On the other hand, the method using fiber optic combined with M57962AL is used to achieve the high voltage drive. The achieved results of experiment demonstrate the feasibility of the proposal, which is quite suitable for HVDC Light and could be widely applied due to the flowing characteristics: the high voltage of isolation, high precision and fast speed of transmission, etc.

  7. 17 beta-estradiol modulates GABAergic synaptic transmission and tonic currents during development in vitro.

    Science.gov (United States)

    Pytel, Maria; Wójtowicz, Tomasz; Mercik, Katarzyna; Sarto-Jackson, Isabella; Sieghart, Werner; Ikonomidou, Chrysanthy; Mozrzymas, Jerzy W

    2007-05-01

    Estrogens exert a variety of modulatory effects on the structure and function of the nervous system. In particular, 17 beta-estradiol was found to affect GABAergic inhibition in adult animals but its action on GABAergic currents during development has not been elucidated. In the present study, we investigated the effect of 17 beta-estradiol on hippocampal neurons developing in vitro. In this model, mIPSC kinetics showed acceleration with age along with increased alpha1 subunit expression, similarly as in vivo. Long-term treatment with 17 beta-estradiol increased mIPSC amplitudes in neurons cultured for 6-8 and 9-11DIV and prolonged the mIPSC decaying phase only in the 9-11DIV group. The time needed for the onset of 17 beta-estradiol effect on mIPSC amplitude was approximately 48 h. In the period of 9-11DIV, treatment with 17 beta-estradiol strongly reduced the tonic conductance activated by low GABA concentrations. The effects of 17 beta-estradiol on mIPSCs and tonic conductance were not correlated with any change in expression of considered GABAAR subunits (alpha1-3, alpha5-6, gamma2) while alpha4 and delta subunits were at the detection limit. In conclusion, we provide evidence that 17 beta-estradiol differentially affects the phasic and tonic components of GABAergic currents in neurons developing in vitro.

  8. Low Insertion HVDC Circuit Breaker: Magnetically Pulsed Hybrid Breaker for HVDC Power Distribution Protection

    Energy Technology Data Exchange (ETDEWEB)

    None

    2012-01-09

    GENI Project: General Atomics is developing a direct current (DC) circuit breaker that could protect the grid from faults 100 times faster than its alternating current (AC) counterparts. Circuit breakers are critical elements in any electrical system. At the grid level, their main function is to isolate parts of the grid where a fault has occurred—such as a downed power line or a transformer explosion—from the rest of the system. DC circuit breakers must interrupt the system during a fault much faster than AC circuit breakers to prevent possible damage to cables, converters and other grid-level components. General Atomics’ high-voltage DC circuit breaker would react in less than 1/1,000th of a second to interrupt current during a fault, preventing potential hazards to people and equipment.

  9. Development and Testing of a Transmission Voltage SuperLimiter™ Fault Current Limiter

    Energy Technology Data Exchange (ETDEWEB)

    Romanosky, Walter [American Superconductor Corporation, Devens, MA (United States)

    2012-09-01

    This report summarizes work by American Superconductor (AMSC), Los Alamos National Laboratory (LANL), Nexans, Siemens and Southern California Edison on a 138kV resistive type high temperature superconductor (HTS) fault current limiter (FCL) under a cooperative agreement with the U.S. Department of Energy (DOE). Phase 1A encompassed core technology development and system design and was previously reported (see summary that follows in Section 1.1 of the Introduction). This report primarily discusses work performed during Phase 1B, and addresses the fabrication and test of a single-phase prototype FCL. The results are presented along with a discussion of requirements/specifications and lessons learned to aid future development and product commercialization.

  10. Nuclear and Solar Energy: Implications for Homeland Security

    Science.gov (United States)

    2008-12-01

    Hirschman Index HVDC High-Voltage Direct Current IPCC Intergovernmental Panel on Climate change NCEP National Commission on Energy Policy NRC...transmission lines will carry the load to the customers along high voltage direct current ( HVDC ) lines. HVDC lines lose 3% of

  11. The Study on Hybrid Multi-Infeed HVDC System Connecting with Offshore Wind Farm

    DEFF Research Database (Denmark)

    Liu, Yan

    , a cooperative control of the VSC-HVDC system and a variable speed Squirrel Cage Induction Generator (SCIG)-based offshore wind farm is proposed. In the approach, an active power-frequency droop control is developed to achieve an autonomous reduction of the generated active powers from wind turbines, which thus...

  12. A generic inertia emulation controller for multi-terminal VSC-HVDC systems

    DEFF Research Database (Denmark)

    Zhu, Jiebei; Guerrero, Josep M.; Booth, Campbell;

    2013-01-01

    A generic Inertia Emulation Controller (INEC) for Multi-Terminal Voltage-source-converter based HVDC (VSC-MTDC) is proposed in this paper. The proposed INEC can be incorporated in any grid-side-voltage-source-converter (GVSC) station, allowing the MTDC terminal to contribute an inertial response...

  13. Design, Control, and Modeling of a New Voltage Source Converter for HVDC System

    Science.gov (United States)

    Mohan, Madhan; Singh, Bhim; Ketan Panigrahi, Bijaya

    2013-05-01

    Abstract: A New Voltage Source Converter (VSC) based on neutral clamped three-level circuit is proposed for High Voltage DC (HVDC) system. The proposed VSC is designed in a multipulse configuration. The converter is operated by Fundamental Frequency Switching (FFS). A new control method is developed for achieving all the necessary control aspects of HVDC system such as independent real and reactive power control, bidirectional real and reactive power control. The basic of the control method is varying the pulse width and by keeping the dc link voltage constant. The steady state and dynamic performances of HVDC system interconnecting two different frequencies network are demonstrated for active and reactive power control. Total number of transformers used in this system are reduced to half in comparison with the two-level VSCs for both active and reactive power control. The performance of the HVDC system is improved in terms of reduced harmonics level even at fundamental frequency switching. The harmonic performance of the designed converter is also studied for different value of the dead angle (β), and the optimized range of the dead angle is achieved for varying reactive power requirement. Simulation results are presented for the designed three level multipulse voltage source converters with the proposed control algorithm.

  14. Coordinated Voltage Control in Offshore HVDC Connected Cluster of Wind Power Plants

    DEFF Research Database (Denmark)

    Sakamuri, Jayachandra N.; Rather, Zakir Hussain; Rimez, Johan;

    2016-01-01

    This paper presents a coordinated voltage control scheme (CVCS) for a cluster of offshore wind power plants (OWPPs) connected to a VSC HVDC system. The primary control point of the proposed voltage control scheme is the introduced Pilot bus, which is having the highest short circuit capacity...

  15. Dynamic Reactive Power Control in Offshore HVDC Connected Wind Power Plants

    DEFF Research Database (Denmark)

    Sakamuri, Jayachandra N.; Cutululis, Nicolaos Antonio; Rather, Zakir Hussain;

    2016-01-01

    This paper presents a coordinated reactive power control for a HVDC connected cluster of offshore wind power plants (WPPs). The reactive power reference for the WPP cluster is estimated by an optimization algorithm aiming at minimum active power losses in the offshore AC Grid. For each optimal...

  16. PowerFactory model for multi-terminal HVDC network with DC voltage droop control

    DEFF Research Database (Denmark)

    Korompili, Asimenia; Wu, Qiuwei

    Nowadays, most of the installed HVDC systems are based on line commutated converters (LCC), since this technology offers a series of advantages, mainly low costs and losses. However, voltage source converters (VSCs) have recently drawn more and more attention, due to their high controllability...

  17. Harmonic Stability Studies in VSC-HVDC Grid Connected Offshore Wind Power Plants

    DEFF Research Database (Denmark)

    Glasdam, Jakob Bærholm; Gevorgian, Vahan; Bak, Claus Leth

    2017-01-01

    the harmonic instability phenomena in HVDC grid connected OWPPs using both frequency and time domain simulations. A good correlation at lower frequencies between the two domains is observed. However, the frequency domain is insufficient at higher frequencies (i.e. in the vicinity of the switching frequency...

  18. Influence of AC line faults on HVDC commutation failure transient characteristics in DC/AC interconnected power grid%直流馈入后交流线路故障对换相失败瞬态特征的影响

    Institute of Scientific and Technical Information of China (English)

    张汝莲; 赵成勇; 卫鹏杰

    2011-01-01

    高压直流(HVDC)输电系统故障会使交流系统电气故障特性复杂化.在PSCAD/EMTDC环境下,基于含宁东--山东直流输电系统的山东电网的电磁暂态模型,研究当青岛换流站附近交流线路不同位置发生不同故障时,直流系统换相失败对交流系统电气瞬态特征的影响.直流系统换相失败对故障线路的平行线路影响最为严重,重点研究交流线路不同故障引一起直流换相失败对平行线路电气特性的影响.仿真分析结果表明,平行线路的故障相电流畸变程度随着故障位置和故障类型的不同而不同,在线路中间发生故障比线路两端故障时畸变严重,发生单相接地短路故障比三相接地短路故障时崎变严重,故在线路中间发生单相接地短路故障时畸变最严重.%The faults of HVDC power transmission system make the electrical characteristics of AC system more complex. In PSCAD/EMTDC environment,based on the electromagnetic transient model of Shandong grid containing Ningdong-Shandong DC transmission system,the influence of HVDC commutation failure on the electrical transient characteristics of AC system is studied for different faults occurring at different positions of AC line near Qingdao substation. During the period of commutation failure,the parallel line of the faulty line is most affected. The influence of commutation failure,caused by different faults of AC line,on the electrical transient characteristics of parallel line is detailed. According to the comparative analysis of simulative results ,the current distortion of the faulty phase of parallel line varies with the fault positions and fault types. It is more serious when the fault occurs in the middle of the line than that when the fault occurs at terminals;it is more serious during single-phase grounding fault than that during three-phase grounding fault. When single-phase grounding fault occurs in the middle of the line ,the current distortion of the

  19. Optimal topology design of multiterminal-HVDC for large offshore wind farms%大规模海上风电场多端直流网拓扑的优化设计

    Institute of Scientific and Technical Information of China (English)

    吴国祥; 孙继国; 吴国庆; 蔡旭

    2015-01-01

    Multiterminal HVDC is a flexible transmission method which supports multi power supply and multi power consumption. It is the trend of large offshore wind farms. Topologies of multiterminal HVDC-VSC transmission for large offshore wind farms were investigated. Various topologies were analyzed ac-cording to a number of criteria, including lines rating, number of HVDC circuit breakers,lines utilization and necessity of an offshore platform. A recommended topological structure was given based on the com-parison. Wind farms ring topology( WFRT) is a optimal topology, which minimises the number of HVDC circuit breakers. The wind farm can still work by breakers and isolators in the event of a circuit fault. Flexibility and redundancy is improved,and case study is given in the situation. The recommended topol-ogy has some guiding significance in the running control of multiterminal DC networks.%多端直流输电能够实现多电源供电、多落点受电,是一种灵活、快捷的输电方式,是海上大规模风电场的发展方向。本文详细分析了海上风电场多端直流网的拓扑结构,对各种拓扑结构的线路容量、直流断路器数量、线路利用率、是否需要海上平台等问题进行了研究。在对各种拓扑结构分析对比的基础上,推荐了一种风电场环形拓扑,该拓扑需要断路器数量少(等于风电场的个数),增加了风电场与电网之间功率控制的柔性,是一种优化的拓扑结构,在输电线路故障时,通过断路器和隔离开关的控制,风电场仍可以向电网发电,提高了系统的灵活性和冗余性,并进行了算例验证。文中推荐的拓扑结构对大规模海上风电场多端直流网的运行控制有一定的指导意义。

  20. Self-commutated high-voltage direct current transmission with DC circuit breakers. Backbone for the energy policy turnaround; Selbstgefuehrte Hochspannungs-Gleichstromuebertragung mit DC-Leistungsschalter. Rueckgrat fuer die Energiewende

    Energy Technology Data Exchange (ETDEWEB)

    Goerner, Raphael [ABB AG, Mannheim (Germany). Marketing und Vertrieb, Geschaeftsbereich Grid Systems

    2013-06-01

    The 'current war' between direct current and alternating current is extended by a new location. In the future, both technologies work together in order to provide a reliable power transmission in Germany and long-term in Europe. This is based on the self-guided high-voltage direct current transmission. In conjunction with direct current circuit breakers (DC circuit breaker) the power circuit breakers may help to make the transmission grids more flexible and to minimize losses.

  1. Electricity Transmission, Pipelines, and National Trails: An Analysis of Current and Potential Intersections on Federal Lands in the Eastern United States, Alaska, and Hawaii

    Energy Technology Data Exchange (ETDEWEB)

    Kuiper, James A. [Argonne National Lab. (ANL), Argonne, IL (United States); Krummel, John R. [Argonne National Lab. (ANL), Argonne, IL (United States); Hlava, Kevin J. [Argonne National Lab. (ANL), Argonne, IL (United States); Moore, H. Robert [Argonne National Lab. (ANL), Argonne, IL (United States); Orr, Andrew B. [Argonne National Lab. (ANL), Argonne, IL (United States); Schlueter, Scott O. [Argonne National Lab. (ANL), Argonne, IL (United States); Sullivan, Robert G. [Argonne National Lab. (ANL), Argonne, IL (United States); Zvolanek, Emily A. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2016-11-21

    As has been noted in many reports and publications, acquiring new or expanded rights-of-way for transmission is a challenging process, because numerous land use and land ownership constraints must be overcome to develop pathways suitable for energy transmission infrastructure. In the eastern U.S., more than twenty federally protected national trails (some of which are thousands of miles long, and cross many states) pose a potential obstacle to the development of new or expanded electricity transmission capacity. However, the scope of this potential problem is not well-documented, and there is no baseline information available that could allow all stakeholders to study routing scenarios that could mitigate impacts on national trails. This report, Electricity Transmission, Pipelines, and National Trails: An Analysis of Current and Potential Intersections on Federal Lands in the Eastern United States, was prepared by the Environmental Science Division of Argonne National Laboratory (Argonne). Argonne was tasked by DOE to analyze the “footprint” of the current network of National Historic and Scenic Trails and the electricity transmission system in the 37 eastern contiguous states, Alaska, and Hawaii; assess the extent to which national trails are affected by electrical transmission; and investigate the extent to which national trails and other sensitive land use types may be affected in the near future by planned transmission lines. Pipelines are secondary to transmission lines for analysis, but are also within the analysis scope in connection with the overall directives of Section 368 of the Energy Policy Act of 2005, and because of the potential for electrical transmission lines being collocated with pipelines.

  2. Altitude Correction of Switching Impulse Flashover Voltage of Tower Gaps With V-shaped Insulator Strings for HVDC Power Transmission Lines%高压直流输电线路V型串塔头间隙操作冲击放电电压的海拔校正

    Institute of Scientific and Technical Information of China (English)

    廖蔚明; 丁玉剑; 孙昭英; 宿志一

    2012-01-01

    介绍了采用相同结构的真型尺寸v型绝缘子串模拟塔头间隙存小同海拔地区开展操作冲击放电特性对比试验取得的成果。根据在北京和西藏(海拔4300m)试验基地获得的塔头『日J隙操作冲击放电特性曲线,采用插值法计算了海拔4000m及以下地区的塔头间隙操作冲击放电曲线。经分析计算,得出了适合海拔4000m及以下地区高压直流线路塔头间隙海拔校正的计算公式。还将通过试验得出的海拔校正计算公式与目前常用标准IEC60071—2—1996推荐的海拔校正计算公式进行了对比,分析了两者的修正因子m值的差别及对修正电压的影响。%The results obtained from contrast tests on switching impulse flashover characteristics of tower gaps under different altitudes by two simulation models with true sizes and actual layouts for V-shaped insulator strings are presented. Based on the curves of switching impulse flashover characteristics of tower gaps obtained respectively from test bases located at Beijing and Tibet individually and the latter is at the region with altitude of 4 300 m, the curves of switching impulse flashover characteristics for tower gaps located at the regions with altitudes of 4 000 m and below are calculated by interpolation method. After analysis and calculation, the altitude-corrected calculation formula of switching impulse flashover characteristics curves for tower gaps, which is suitable to the regions with altitudes of 4 000 m and below, is obtained. The comparison of altitude correction computing formula obtained from tests with the formula recommended by IEC 60071-2: 1996, which is common used currently, is performed, and the difference between the values of correction factors m in the two formulae as well as the impact of the two correction factors on switching impulse flashover voltage are analyzed.

  3. Review of Low Voltage Ride-Through Technology for VSC-HVDC Based Wind Power Generation Systems%基于VSC-HVDC的风电系统低电压穿越技术综述

    Institute of Scientific and Technical Information of China (English)

    章心因; 吴在军; 郝思鹏; 程桂林

    2013-01-01

      轻型高压直流输电系统(VSC-HVDC)是风电技术的重要发展方向。随着风电比重快速增加,电网对风电机组及其并网系统地低电压穿越(LVRT)能力提出了更高的要求。本文首先分析了电压跌落对VSC-HVDC系统和风电机组的影响,继而简要地总结了风电机组LVRT技术,然后对各种适合于VSC-HVDC风电系统的LVRT方案进行了分析评价,并重点讨论了该风电系统的LVRT协调控制技术。%Long-distance large-capacity wind farm connected to the grid by the VSC-HVDC transmission system will be an important trend of the wind power technology development. With the rapid increase in the proportion of wind power, the grid has a higher demand for the Low Voltage Ride-through(LVRT) ability of the wind turbine and its grid systems. The influence of voltage drop on the VSC-HVDC system and wind turbine is firstly analyzed. Meanwhile, the LVRT technology for the wind turbine is summarized briefly. Then, several types of LVRT solutions for the VSC-HVDC based wind power systems are analyzed and evaluated. In the end, the LVRT coordination control methods are mainly discussed.

  4. Development and Outlook of Insulating Materials for High Voltage Direct Current Cables%高压直流电缆绝缘材料的发展与展望

    Institute of Scientific and Technical Information of China (English)

    张翀; 查俊伟; 王思蛟; 巫运辉; 闫轰达; 李维康; 陈新; 党智敏

    2016-01-01

    针对高压直流电缆的发展历史,介绍了高压直流电缆的基本原理、应用现状以及技术瓶颈,指出我国研发高压直流电缆的必要性和紧迫性,并对未来高压直流电缆的发展方向进行了展望.%The basic principle, application status, and technical bottlenecks of high voltage direct current (HVDC) cables were introduced according to the history of HVDC cables, and the necessity and urgency for developing HVDC cables were pionted out in China. The future development direction of HVDC cables was prospected.

  5. Mid-Atlantic Offshore Wind Interconnection and Transmission (MAOWIT)

    Energy Technology Data Exchange (ETDEWEB)

    Kempton, Willett [Univ. of Delaware, Newark, DE (United States)

    2016-04-05

    This project has carried out a detailed analysis to evaluate the pros and cons of offshore transmission, a possible method to decrease balance-of-system costs and permitting time identified in the DOE Office Wind Strategic Plan (DOE, 2011). It also addresses questions regarding the adequacy of existing transmission infrastructure and the ability of existing generating resources to provide the necessary Ancillary Services (A/S) support (spinning and contingency reserves) in the ISO territory. This project has completed the tasks identified in the proposal: 1. Evaluation of the offshore wind resource off PJM, then examination of offshore wind penetrations consistent with U.S. Department of Energy’s (DOE) targets and with their assumed resource size (DOE, 2011). 2. Comparison of piecemeal radial connections to the Independent System Operator (ISO) with connections via a high-voltage direct current (HVDC) offshore network similar to a team partner. 3. High-resolution examination of power fluctuations at each node due to wind energy variability 4. Analysis of wind power production profiles over the Eastern offshore region of the regional ISO to assess the effectiveness of long-distance, North- South transmission for leveling offshore wind energy output 5. Analysis of how the third and fourth items affect the need for ISO grid upgrades, congestion management, and demand for Ancillary Services (A/S) 6. Analysis of actual historic 36-hr and 24-hr forecasts to solve the unit commitment problem and determine the optimal mix of generators given the need to respond to both wind variability and wind forecasting uncertainties.

  6. Facts for improving the efficiency and quality of alternating current transmission systems; Facts para mejorar la eficacia y la calidad de los sistemas de transmision de corriente alterna

    Energy Technology Data Exchange (ETDEWEB)

    Grunbaum, R.

    2008-07-01

    The power supply industry is undergoing change as a result of deregulation and political and economical detente in many parts of the world. This new market environment puts growing demands for flexibility and power quality into focus. Also, trade of electric power between countries is gaining momentum, and wind power is starting to yield serious contributions to the generation balance. With Facts (Flexible Alternating Current Transmission Systems), more power can be transmitted with unimpeded availability at an investment cost and time expenditure lower, or in cases even far lower than it would cost to achieve the same with more extensive grids. Also, in many cases, money can be saved on a decrease of power transmission losses. From an environmental point of view, Facts enables the transmission of power with less right-of-way impact than would otherwise be possible. Furthermore, the saving in transmission losses may well bring about a correspond decrease in need of power generation. (Author)

  7. Robust Global Control Strategies for Improvement of Angular Stability using FACTS and HVDC Devices

    Science.gov (United States)

    Agnihotri, P.; Kulkarni, A. M.; Gole, A. M.

    2013-05-01

    System-wide feedback signals made available by Wide-Area Measurement Systems technology can be used in FACTS/HVDC based controllers for the improvement of angular stability. These global signals can facilitate the efficient use of controller effort to stabilize critical swing modes. This paper introduces a restricted global strategy which involves the use of specific global feedback signals which are available at the HVDC/FACTS locations. The strategy is expected to be robust to changes in the power grid as well as communication uncertainties. This paper presents a heuristic introduction to this strategy using a circuit analogy of a simplified model of a power system. Preliminary results on a small system are also presented.

  8. Wide-Area Robust Decentralized Coordinated Control of HVDC Power System Based on Polytopic System Theory

    Directory of Open Access Journals (Sweden)

    Shiyun Xu

    2015-01-01

    Full Text Available The present study proposes a hierarchical wide-area decentralized coordinated control framework for HVDC power system that is robust to multiple operating conditions. The upper level wide-area coordinated controller is designed in the form of dynamic output feedback control that coordinates the lower level HVDC supplementary controller, PSS, and SVC. In order to enhance the robustness of the designed controller under various operating conditions, the polytopic model is introduced such that the closed-loop control system can be operated under strong damping mode in virtue of the stability criterion based on damping ratio. Simulation results demonstrate that the proposed controller design algorithm is capable of enhancing the system damping over four different conditions.

  9. Tailored sPP/Silica Nanocomposite for Ecofriendly Insulation of Extruded HVDC Cable

    Directory of Open Access Journals (Sweden)

    Bin Dang

    2015-01-01

    Full Text Available Cross-linked polyethylene (XLPE is a thermosetting material that cannot be recycled at the end of its lifetime. This study investigated the potential of syndiotactic polypropylene (sPP/silica as an ecofriendly extruded insulation system for HVDC cables. We investigated the morphology, Fourier transform infrared, and thermal, thermomechanical, and electrical behaviors of sPP modified with 0.5–3% nanosilica. We found that the silica/sPP nanocomposite without cross-linking offered a suitable mechanical modulus at room temperature and sufficient intensity at high temperatures, and adding nanosilica modified by a silane coupling agent to the sPP resulted in significant DC resistivity and space charge improvement. The optimal nanosilica content in the sPP was determined by balancing the mechanical and thermomechanical characteristics and the DC resistivity. The sPP/silica nanocomposite reported here shows great potential as a candidate insulation material for future ecofriendly extruded HVDC cables.

  10. Harmonic Analysis of VSC-HVDC%VSC-HVDC的谐波分析

    Institute of Scientific and Technical Information of China (English)

    胡弢

    2009-01-01

    基于电压源换流器的高压直流输电技术(VSC-HVDC)已经在电力系统中得到了应用.针对采用双闭环解耦控制的VSC-HVDC,对其谐渡产生机理进行了详细的理论分析和数学推导,并针对分析结果提出了变调制度的谐波抑制措施:通过Matlab/Simulink(建立了VSC-HVDC供电有源系统的仿真模型,仿真结果验证了理论分析的正确性和谐波抑制措施的有效性.

  11. Power system analysis of Hanlim superconducting HVDC system using real time digital simulator

    Science.gov (United States)

    Won, Y. J.; Kim, J. G.; Kim, A. R.; Kim, G. H.; Park, M.; Yu, I. K.; Sim, K. D.; Cho, J.; Lee, S.; Jeong, K. W.; Watanabe, K.

    2011-11-01

    Jeju island is located approximately 100 km south from the mainland of Korea, and had a peak load of about 553 MW in 2008. The demand increases 7.2% a year over the last 5 years. Since the wind profiles of Jeju island are more favorable than mainland of Korea, many companies have shown interest in the wind power business at the Jeju island. Moreover KEPCO has a plan for renewable energy test too whose power will be delivered by HVDC system. One kilometer length of total 8 km was designed as superconducting DC cable. Rest 7 km will be the conventional overhead line. In this paper, the authors have developed a simulation model of the power network around 8 km HVDC system using real time digital simulator (RTDS).

  12. 自激式SVC在HVDC中的应用%Auto-Excitation Type SVC Applied in HVDC

    Institute of Scientific and Technical Information of China (English)

    陈玉安; 李燕平

    2002-01-01

    @@ 1问题的提出 直流输电(HVDC)以其易于联网、系统稳定、宜大功率远距离输电一系列优点正被世界各国所采用.目前,HVDC的换流装置所使用的是换相关断型晶闸管构成的它激式换流器.

  13. Simulation Model of the Future Nordic Power Grid Considering the Impact of HVDC Links

    OpenAIRE

    Aas, Even Strand

    2016-01-01

    As Europe is shifting to an increasingly larger share of non-dispatchable renewable energy sources, the cross-border power flow changes. This thesis considers further development of an existing PowerFactory simulation model designed to fit with new power flow situations influencing the Nordic power system. Today, there are many HVDC links connecting Europe to the Nordic grid, and there are several new links being built and planned. The thesis work is a continuation of an earlier specialisatio...

  14. Electricity Transmission, Pipelines, and National Trails. An Analysis of Current and Potential Intersections on Federal Lands in the Eastern United States, Alaska, and Hawaii

    Energy Technology Data Exchange (ETDEWEB)

    Kuiper, James A; Krummel, John R; Hlava, Kevin J; Moore, H Robert; Orr, Andrew B; Schlueter, Scott O; Sullivan, Robert G; Zvolanek, Emily A

    2014-03-25

    As has been noted in many reports and publications, acquiring new or expanded rights-of-way for transmission is a challenging process, because numerous land use and land ownership constraints must be overcome to develop pathways suitable for energy transmission infrastructure. In the eastern U.S., more than twenty federally protected national trails (some of which are thousands of miles long, and cross many states) pose a potential obstacle to the development of new or expanded electricity transmission capacity. However, the scope of this potential problem is not well-documented, and there is no baseline information available that could allow all stakeholders to study routing scenarios that could mitigate impacts on national trails. This report, Electricity Transmission, Pipelines, and National Trails: An Analysis of Current and Potential Intersections on Federal Lands in the Eastern United States, was prepared by the Environmental Science Division of Argonne National Laboratory (Argonne). Argonne was tasked by DOE to analyze the “footprint” of the current network of National Historic and Scenic Trails and the electricity transmission system in the 37 eastern contiguous states, Alaska, and Hawaii; assess the extent to which national trails are affected by electrical transmission; and investigate the extent to which national trails and other sensitive land use types may be affected in the near future by planned transmission lines. Pipelines are secondary to transmission lines for analysis, but are also within the analysis scope in connection with the overall directives of Section 368 of the Energy Policy Act of 2005, and because of the potential for electrical transmission lines being collocated with pipelines. Based on Platts electrical transmission line data, a total of 101 existing intersections with national trails on federal land were found, and 20 proposed intersections. Transmission lines and pipelines are proposed in Alaska; however there are no

  15. Effects of interactions between stations on the calculation of geomagnetically induced currents in an electric power transmission system

    Science.gov (United States)

    Pirjola, R.

    2008-07-01

    "Geomagnetically induced currents" (GIC) in ground-based technological networks are a manifestation of space weather. GIC are a potential source of problems to the systems and therefore important in practice. GIC in a power system (or in principle in any other discretely-earthed system) can be calculated conveniently by using matrix equations presented earlier. Since temporal variations associated with GIC are slow compared to the 50/60 Hz frequency used in power transmission, a dc treatment is acceptable. An essential quantity in calculations of GIC in a power grid is the earthing impedance matrix, which is the transfer function coupling GIC flowing to (from) the Earth with the voltages between the earthing points, called nodes or (sub)stations, and a remote earth. The diagonal elements of the matrix equal the earthing resistances of the nodes whereas an off-diagonal element expresses how much GIC at one earthing point affects the voltage at another node. In GIC calculations, except for some special treatments of individual sites, the off-diagonal elements are usually neglected by saying simply that the earthing points (are assumed to) lie distantly enough. In this paper, we examine the effects of off-diagonal elements of the earthing impedance matrix, i.e. the effects of interactions between different stations, on GIC calculations in greater detail and more quantitatively than before. We consider a fictitious system that represents a high-voltage power grid and a simple "network" consisting of two stations with a line connecting them. For both systems, the conclusion can be drawn that the off-diagonal elements do not play a major role in practice. Modelling them only approximately, or even ignoring them, is not of great significance compared to other shortcomings involved in GIC calculations. This is particularly true when looking at a power grid as a whole although at some individual stations the neglect may lead to larger errors in GIC values.

  16. Study Configuration of the Protection of Transfer between Ground Return and Metallic Return in the Tian-Guang HVDC Project%天广直流输电系统中大地回线和金属回线转换的保护配置研究

    Institute of Scientific and Technical Information of China (English)

    杨贵军

    2012-01-01

      天广直流输电工程采用南瑞PCS-9550直流控制保护系统,在直流系统单极大地回线和单极金属回线转换过程中配置了金属回线转换开关保护(MRTB)和金属回线开关保护(MRS),避免了天广直流系统运行中因为LC振荡回路故障,MRTB和MRS开关断口间电弧重燃或者直流系统控制保护软件缺陷、硬件板卡、测量装置故障,导致在金属和大地回线转换失败,造成直流系统停用的严重后果,提高了天广直流系统运行的可靠性。%  Tian-Guang HVDC transmission project with NARI PCS-9550 DC control and protection system, between Ground Return and Metal ic Return in the Tian-Guang HVDC Project configurat the Metal ic Return Transform-breaker protection(MRTB) and the Metal ic Return Switch protection (MRS),to avoid the operation of the Tian-Guang HVDC Project, Because the LC oscil ator circuit failure, MRTB and MRS Switch-Fracture Arc reneweding and DC system control and protection software bugs, hardware board, measuring device failure, Resulting the Serious consequences of theTransfering between Ground Return and Metal ic Return failed creating DC system disabled. Improve Tian-Guang HVDC system operated reliability.

  17. 高海拔直流工程主设备状态评估的修正方法%Modification of Condition Assessment for HVDC Equipment Used in High Altitude Area

    Institute of Scientific and Technical Information of China (English)

    王健一; 李金忠; 李军; 吴超; 祝令瑜

    2016-01-01

    ABSTRACT:In order to make a more accurate and effective assessment of the status of the main equipment of the±400kV Qingzang HVDC project, which is the world’s highest altitude transmission project, the impact of high altitude on the operation of HVDC equipment was studied, and the correction model of condition assessment of HVDC equipment was proposed. External insulation strength, heat-sinking capability, ultraviolet radiation, and temperature difference day and night in high altitude area were analyzed theoretically. The state parameters which need to be revised at high altitude were selected based on the correlation analysis. Referring to the Condition Evaluation Guide established by State Grid, the weight of the condition variables related to altitude was revised, and the evaluation method for HVDC equipment in high altitude area was proposed. The remote condition monitoring and operation condition evaluation system for primary equipment of±400kV Qingzang HVDC project was established in the mode of concentrated construction. It is demonstrated that the altitude correction factors can effectively improve the accuracy of condition assessment of HVDC equipment operation in high altitude.%为了对世界上海拔最高的高原输电工程——青藏直流联网工程的主设备状态进行更为准确有效的评估,该文对高海拔环境对高压直流输电主设备运行的影响展开研究,提出高海拔直流输电设备状态评估参数的修正方法。从理论上分析了高海拔下外绝缘强度、散热能力、紫外辐射、昼夜温差等方面对设备的影响,并基于相关性分析筛选出了高海拔下所需要修正的状态量。根据国网的状态评价导则以及低海拔地区的大量运行经验,建立了考虑高海拔条件的主设备运行  状态评价方法,对与海拔相关的状态量及其权系数进行了海拔修正。基于已建立的状态评价方法,建立了±400 kV青藏直流工程

  18. Total Eddy Currents Induced in Screens of a Symmetrical Three-Phase Single-Pole Gas-Insulated Transmission Line (GIL

    Directory of Open Access Journals (Sweden)

    Zygmunt Piatek

    2008-01-01

    Full Text Available In the paper we discuss the question of eddy currents induced in screens of a symmetrical three-phase singlepole gas-insulated transmission line (GIL. First, we determine the eddy currents induced in the tubular screen by the magnetic field of self-current of the phase conductor. Then the magnetic field in the external parallel phase conductor is presented by means of a vector magnetic potential as Fourrier series. In the non-conducting external and internal area of the screen we use Laplace equation for the magnetic field strength taking into account the reverse reaction of eddy currents induced in the screen. In the conducting screen we apply Helmholtz equation for eddy currents density. Using classical boundary conditions we determine the density of the currents. The solutions obtained are used to determine the total eddy currents induced in all the screens of the GIL under consideration.

  19. A New Coordinated Voltage Control Scheme for Offshore AC Grid of HVDC Connected Offshore Wind Power Plants

    DEFF Research Database (Denmark)

    Sakamuri, Jayachandra N.; Cutululis, Nicolaos Antonio; Rather, Zakir Hussain;

    2015-01-01

    This paper proposes a coordinated voltage control scheme (CVCS) which enhances the voltage ride through (VRT) capability of an offshore AC grid comprised of a cluster of offshore wind power plants (WPP) connected through AC cables to the offshore voltage source converter based high voltage DC (VSC-HVDC......) converter station. Due to limited short circuit power contribution from power electronic interfaced variable speed wind generators and with the onshore main grid decoupled by the HVDC link, the offshore AC grid becomes more vulnerable to dynamic voltage events. Therefore, a short circuit fault...... in the offshore AC Grid is likely to have significant implications on the voltage of the offshore AC grid, hence on the power flow to the onshore mainland grid. The proposed CVCS integrates individual local reactive power control of wind turbines and of the HVDC converter with the secondary voltage controller...

  20. Auxiliary Equipment Based Processing Strategy for MMC-HVDC DC Faults%基于辅助电路的 MMC-HVDC 直流故障处理策略

    Institute of Scientific and Technical Information of China (English)

    郭敬梅; 曾德辉; 王钢; 李海锋

    2016-01-01

    直流线路故障是基于模块化多电平换流器的高压直流输电(MMC‐HVDC)系统必须解决的关键问题。文中提出一种基于辅助电路的直流故障处理策略,即双向晶闸管与开关型零损耗限流装置相配合的保护方案。首先分析了直流故障电流自然衰减的直流保护原理及现有方案的缺陷,进而提出采用双向晶闸管代替背靠背晶闸管集中配置在交流侧的方法来简化其控制回路;通过与开关型零损耗限流装置相配合,并对限流电抗器进行合理设计,能够使保护在不增加运行损耗的同时具有快速抑制短路电流的能力,降低清除直流故障时对交流系统长时间的冲击。此外,进一步提出相应的故障检测及恢复策略。最后,基于 PSCAD 仿真平台验证了所述保护方案的有效性。%The DC‐link fault is a key issue for the flexible high‐voltage direct current system using modular multilevel converter ( MMC‐HVDC) . An auxiliary equipment based processing strategy for MMC‐HVDC DC faults is proposed , namely , a novel scheme by bidirectional thyristors in collaboration with a breaker‐type zero‐loss fault current limiter . The DC‐protections based on natural decay of the fault DC current and their shortcomings are analyzed first . It is then proposed that the bidirectional thyristors rather than back‐to‐back ones are configured and controlled on the AC‐side to simplify the control loop . The bidirectional thyristors are controlled to cooperate with the appropriately designed breaker‐type zero‐loss fault current limiter , which can possess fast current limiting ability while reducing the long short‐circuit current rush to AC system during the clearance of the DC‐link fault . And the corresponding DC‐fault detection and recovery strategy is presented . PSCAD based simulation results finally verify the validity of the proposed protection scheme .

  1. Basic Characteristics of New Developed Higher-Voltage Direct-Current Power-Feeding Prototype System

    Science.gov (United States)

    Babasaki, Tadatoshi; Tanaka, Toshimitsu; Tanaka, Toru; Nozaki, Yousuke; Aoki, Tadahito; Kurokawa, Fujio

    High efficiency power feeding systems are effective solutions for reducing the ICT power consumption with reducing power consumption of the ICT equipment and cooling systems. A higher voltage direct current (HVDC) power feeding system prototype was produced. This system is composed of a rectifier equipment, power distribution unit, batteries, and the ICT equipment. The configuration is similar to a -48V DC power supply system. The output of the rectifier equipment is 100kW, and the output voltage is 401.4V. This paper present the configuration of the HVDC power feeding system and discuss its basic characteristics in the prototype system.

  2. 汽车自动变速器油的技术现状与发展趋势%Current Technology and Development Trends of Automatic Transmission Fluids

    Institute of Scientific and Technical Information of China (English)

    李茂生; 杜群贵; 贾继欣

    2014-01-01

    The types,characteristics and developing direction of vehicle automatic transmission,and the technical re-quirement,current technological state and development trend of automatic transmission fluids (ATF/CVTF ) were de-scribed.The tribological characteristics and evaluation method of ATF/CVTF were introduced.The development and appli-cation of new automatic transmission fluids and its corresponding evaluation test methods of physical and chemical proper-ties,friction characteristics and wear state,the development of the specifications and standard of automatic transmission flu-ids are key common technologies for development of automatic transmission.%论述汽车自动变速器(AT、CVT)的类型、特点及发展方向,以及与其配套的变速器油(ATF、CVTF)的技术现状和发展趋势,介绍ATF/CVTF的摩擦学特性及其评价方法。开发和应用新型自动变速器油及其相应的摩擦特性测试方法、磨损状态评定手段和油品理化性能测试方法及台架试验方法,制定自动变速器油的规格标准,是促进自动变速器发展的关键共性技术。

  3. A tool for stability and power sharing analysis of a generalized class of droop controllers for high-voltage direct-current transmission systems

    OpenAIRE

    2016-01-01

    The problem of primary control of high-voltage direct current transmission systems is addressed in this paper, which contains four main contributions. First, to propose a new nonlinear, more realistic, model for the system suitable for primary control design, which takes into account nonlinearities introduced by conventional inner controllers. Second, to determine necessary conditions---dependent on some free controller tuning parameters---for the existence of equilibria. Third, to formulate ...

  4. Statistical characteristic in time-domain of direct current corona-generated audible noise from conductor in corona cage

    Science.gov (United States)

    Li, Xuebao; Cui, Xiang; Lu, Tiebing; Ma, Wenzuo; Bian, Xingming; Wang, Donglai; Hiziroglu, Huseyin

    2016-03-01

    The corona-generated audible noise (AN) has become one of decisive factors in the design of high voltage direct current (HVDC) transmission lines. The AN from transmission lines can be attributed to sound pressure pulses which are generated by the multiple corona sources formed on the conductor, i.e., transmission lines. In this paper, a detailed time-domain characteristics of the sound pressure pulses, which are generated by the DC corona discharges formed over the surfaces of a stranded conductors, are investigated systematically in a laboratory settings using a corona cage structure. The amplitude of sound pressure pulse and its time intervals are extracted by observing a direct correlation between corona current pulses and corona-generated sound pressure pulses. Based on the statistical characteristics, a stochastic model is presented for simulating the sound pressure pulses due to DC corona discharges occurring on conductors. The proposed stochastic model is validated by comparing the calculated and measured A-weighted sound pressure level (SPL). The proposed model is then used to analyze the influence of the pulse amplitudes and pulse rate on the SPL. Furthermore, a mathematical relationship is found between the SPL and conductor diameter, electric field, and radial distance.

  5. Statistical characteristic in time-domain of direct current corona-generated audible noise from conductor in corona cage

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xuebao, E-mail: lxb08357x@ncepu.edu.cn; Cui, Xiang, E-mail: x.cui@ncepu.edu.cn; Ma, Wenzuo; Bian, Xingming; Wang, Donglai [State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, North China Electric Power University, Beijing 102206 (China); Lu, Tiebing, E-mail: tiebinglu@ncepu.edu.cn [Beijing Key Laboratory of High Voltage and EMC, North China Electric Power University, Beijing 102206 (China); Hiziroglu, Huseyin [Department of Electrical and Computer Engineering, Kettering University, Flint, Michigan 48504 (United States)

    2016-03-15

    The corona-generated audible noise (AN) has become one of decisive factors in the design of high voltage direct current (HVDC) transmission lines. The AN from transmission lines can be attributed to sound pressure pulses which are generated by the multiple corona sources formed on the conductor, i.e., transmission lines. In this paper, a detailed time-domain characteristics of the sound pressure pulses, which are generated by the DC corona discharges formed over the surfaces of a stranded conductors, are investigated systematically in a laboratory settings using a corona cage structure. The amplitude of sound pressure pulse and its time intervals are extracted by observing a direct correlation between corona current pulses and corona-generated sound pressure pulses. Based on the statistical characteristics, a stochastic model is presented for simulating the sound pressure pulses due to DC corona discharges occurring on conductors. The proposed stochastic model is validated by comparing the calculated and measured A-weighted sound pressure level (SPL). The proposed model is then used to analyze the influence of the pulse amplitudes and pulse rate on the SPL. Furthermore, a mathematical relationship is found between the SPL and conductor diameter, electric field, and radial distance.

  6. 计及直流控制特性的直流系统等值模型及其谐波计算%HVDC System Equivalent Model and Harmonic Calculation with DC Control System Characteristics Taken into Account

    Institute of Scientific and Technical Information of China (English)

    刘俊磊; 王钢; 李海锋; 周全; 郑伟

    2014-01-01

    An accurate converter model is the foundation of AC/DC system fault analysis and harmonic calculation.Based on the dynamic switching characteristics of inverter and fault response characteristics of DC control system of various fault-types,a DC system model able to directly interface with AC systems is developed for AC/DC system fault analysis and harmonic calculation.By referring to the AC and DC power grid harmonic equivalent network,an high voltage direct current (HVDC) system harmonic calculation method suitable for AC asymmetric fault condition is proposed.The method is used in the harmonic calculation of CIGRE HVDC system and Guiguang Ⅱ HVDC system.Compared with simulation results using PSCAD/EMTDC software,the results obtained show that the proposed model and method are accurate and effective,providing a basis for quantitative analysis of harmonic mitigation,filter configuration and protection setting of the AC/DC system.%准确的直流系统模型是交直流系统故障分析和谐波计算的基础。文中在换流器开关函数模型的基础上,结合直流控制系统的故障响应特性,建立了可与交流系统直接接口的适用于交直流系统故障分析和谐波计算的直流系统等值模型;结合交流系统等值谐波网络,提出了一种交流电网故障时的高压直流输电系统谐波分析计算方法。将所提方法应用于国际大电网会议高压直流输电(CIGRE HVDC)系统标准模型和贵广Ⅱ回高压直流输电系统详细模型的谐波计算,并与PSCAD/EMTDC软件所得数字仿真结果进行比较,表明所提模型和方法准确、有效,为交直流输电系统的谐波抑制、滤波装置的配置和继电保护的整定配合等提供了定量分析依据。

  7. Method of Calculation of Current of the Ground Faults in the Parallel Overhead Transmission Lines 110-220 Kv

    Directory of Open Access Journals (Sweden)

    Ukraintsev Alexandr V.

    2017-01-01

    Full Text Available The mutual induction between the phase wires of the different overhead lines which situate close to each other cause unbalanced redistribution of currents in the line wires. This leads to emergence of the outof-balance zero sequence current which affects negatively on the sensitivity of the zero-sequence current protection. It is impossible to estimate such out-ofbalance current by the means of the typical calculation programs for short circuit currents. This paper describes the method of “virtual” lines for an extra correction of the values of zero-sequence currents during the current ground faults happening in the overhead lines 110-220 kV. There is an example of using this method for three parallel overhead lines 220 kV passing close to each other.

  8. Design and Operation Principles of DC Circuit Breakers - Development of a Solid State DC Breaker for the NTNU/SINTEF Smart Grid and Renewable Energy Laboratory

    OpenAIRE

    Norum, Eivind Ødegaard

    2016-01-01

    Exciting high voltage direct current (HVDC) transmission systems are mainly point-to-point connections. A multi-terminal HVDC grid consisting of three or more inter connected converter stations is suggested in order to increase the reliability, redundancy and flexibility in long distant bulk power transmission. Similar to AC (alternating current) grids, a protection system of HVDC-grids must be able to clear faults without affecting the remaining healthy parts of the grid. Thus, there is a ne...

  9. Complete Localization of HVDC Back-to-Back Project Realized

    Institute of Scientific and Technical Information of China (English)

    Yu Xinqiang; Liang Xuming; Wang Zuli; Ye Qing

    2006-01-01

    The first completely localized DC back-to-back project for asynchronous interconnection between Northwest and Central China plays an important role in realizing national power grid interconnection, spurring indigenous manufacturing industries and promoting DC transmission equipment. Insisting on the principle of autonomous innovation, this project was based on domestic forces in every aspect, from engineering organization, system design, equipment completion, engineering design, equipment manufacturing and procurement to construction and debugging. By passing through strict quality control, intermediate supervision and acceptance test and assessment, the project has been proved up to world advanced level.

  10. Analyzing the transmission structures of long continuing current processes from negative ground flashes on the Qinghai-Tibetan Plateau

    Science.gov (United States)

    Fan, Xiangpeng; Zhang, Guangshu; Wang, Yanhui; Li, Yajun; Zhang, Tong; Wu, Bin

    2014-03-01

    This paper presents a new overlap and progressive method using either a one-point charge model or a point dipole model for studying the electric field change data of lightning and tests the suitability of the proposed method by analyzing the slow electric field change of the long continuing current data from two negative ground flashes. The current measurements of the ground flashes are from the Composite Observing Experiment for Lightning project carried out in the Datong region of Qinghai Province, China, in 2009, obtained from field observations synchronized through high-precision GPS clocks at seven observation stations. Analysis shows that the time-averaged current can reach 800 A, and the current intensity relates to the height of the top of the return stroke before the continuing current process. The two current processes studied in this work neutralized a large amount of negative charge, 39.5C and 60.8C, respectively. The neutralized charges from the negative charge layer are typically at 2.5-4.7 km above ground. The intracloud transition of the positive leader is a complex process, and the horizontal propagation of the positive leader plays an important role in current duration as well as horizontally influencing the center of the electrical dipole moment with an obvious change of up to 3.0 km. The proposed analysis method is very useful compared to previous methods in terms of determining infinitesimal changes in long continuing currents. This work's new analysis method will help increase understanding of the fine physical processes of long continuing current processes.

  11. Determination of High-Frequency Current Distribution Using EMTP-Based Transmission Line Models with Resulting Radiated Electromagnetic Fields

    Energy Technology Data Exchange (ETDEWEB)

    Mork, B; Nelson, R; Kirkendall, B; Stenvig, N

    2009-11-30

    Application of BPL technologies to existing overhead high-voltage power lines would benefit greatly from improved simulation tools capable of predicting performance - such as the electromagnetic fields radiated from such lines. Existing EMTP-based frequency-dependent line models are attractive since their parameters are derived from physical design dimensions which are easily obtained. However, to calculate the radiated electromagnetic fields, detailed current distributions need to be determined. This paper presents a method of using EMTP line models to determine the current distribution on the lines, as well as a technique for using these current distributions to determine the radiated electromagnetic fields.

  12. Study on controlling of VSC- HVDC based on advanced phase locked loop technique%基于改进锁相环的柔性直流输电系统控制研究

    Institute of Scientific and Technical Information of China (English)

    郑连清; 池俊锋; 陈杰

    2011-01-01

    Under AC power system frequency excursion and harmonics produced by switching devices, detecting synchronous phase and instantaneous symmetrical components quickly and accurately is an important part of the control and protection system of voltage source converter based high-voltage direct current transmission ( VSC - HVDC). Combined with the conception of SPLL and the VSC - HVD system, which can make the independence decoupling of the active power and the reactive power, devising a new system for three-phase phase-locked loop, with double-phase discriminators. According to eliminate the double frequency, reducing the system's main error, and at same time, making PI regulator has better frequency response characteristics and better frequency locking ability. It is verified by PSCAD that dynamic response of the system can be improved and locking frequency range of phase can be extended.%针对系统频率波动、开关器件动作产生大量的谐波等问题,快速、准确地提供同步相位,是基于电压源型换流器的高压直流输电系统实现控制和保护的关键问题.通过引进软件锁相环概念(SPLL),并结合VSC-HVDC系统能瞬间实现有功、无功解耦的特点,设计了双鉴相器的三相锁相系统.通过消除二倍频,抑制了引起误差的主要因素,同时使PI调节器具有更好的频率锁定和响应特性.通过PSCAD对改进前后系统的在消除谐波、提高系统整体性能,以及电网频率一定范围内突变时系统的响应特性等方面进行比较,实现了对原理的验证.

  13. Evaluation of half-bridge modular multilevel converter model for VSC-HVDC transient stability studies

    DEFF Research Database (Denmark)

    Irnawan, Roni; Silva, Filipe Miguel Faria da; Bak, Claus Leth

    2017-01-01

    is described. This RMS model is then simplified by neglecting the inner/current controller. Both detailed and simplified RMS models are then validated against an accurate electromagnetic (EMT) transient model in a point-to-point (PtP) transmission system with different AC network strength, power directions...

  14. Chagas disease: current epidemiological trends after the interruption of vectorial and transfusional transmission in the Southern Cone countries.

    Science.gov (United States)

    Moncayo, Alvaro

    2003-07-01

    Chagas disease, named after Carlos Chagas who first described it in 1909, exists only on the American Continent. It is caused by a parasite, Trypanosoma cruzi, transmitted to humans by blood-sucking triatomine bugs and by blood transfusion. Chagas disease has two successive phases, acute and chronic. The acute phase lasts 6 to 8 weeks. After several years of starting the chronic phase, 20% to 35% of the infected individuals, depending on the geographical area will develop irreversible lesions of the autonomous nervous system in the heart, esophagus, colon and the peripheral nervous system. Data on the prevalence and distribution of Chagas disease improved in quality during the 1980's as a result of the demographically representative cross-sectional studies carried out in countries where accurate information was not available. A group of experts met in Bras lia in 1979 and devised standard protocols to carry out countrywide prevalence studies on human T. cruzi infection and triatomine house infestation. Thanks to a coordinated multi-country program in the Southern Cone countries the transmission of Chagas disease by vectors and by blood transfusion has been interrupted in Uruguay in1997, in Chile in 1999, and in 8 of the 12 endemic states of Brazil in 2000 and so the incidence of new infections by T. cruzi in the whole continent has decreased by 70%. Similar control multi-country initiatives have been launched in the Andean countries and in Central America and rapid progress has been recorded to ensure the interruption of the transmission of Chagas disease by 2005 as requested by a Resolution of the World Health Assembly approved in 1998. The cost-benefit analysis of the investments of the vector control program in Brazil indicate that there are savings of US$17 in medical care and disabilities for each dollar spent on prevention, showing that the program is a health investment with good return. Since the inception in 1979 of the Steering Committee on Chagas Disease

  15. Transmission of the electric fields to the low latitude ionosphere in the magnetosphere-ionosphere current circuit

    Science.gov (United States)

    Kikuchi, Takashi; Hashimoto, Kumiko K.

    2016-12-01

    The solar wind energy is transmitted to low latitude ionosphere in a current circuit from a dynamo in the magnetosphere to the equatorial ionosphere via the polar ionosphere. During the substorm growth phase and storm main phase, the dawn-to-dusk convection electric field is intensified by the southward interplanetary magnetic field (IMF), driving the ionospheric DP2 currents composed of two-cell Hall current vortices in high latitudes and Pedersen currents amplified at the dayside equator (EEJ). The EEJ-Region-1 field-aligned current (R1 FAC) circuit is completed via the Pedersen currents in midlatitude. On the other hand, the shielding electric field and the Region-2 FACs develop in the inner magnetosphere, tending to cancel the convection electric field at the mid-equatorial latitudes. The shielding often causes overshielding when the convection electric field reduces substantially and the EEJ is overcome by the counter electrojet (CEJ), leading to that even the quasi-periodic DP2 fluctuations are contributed by the overshielding as being composed of the EEJ and CEJ. The overshielding develop significantly during substorms and storms, leading to that the mid and low latitude ionosphere is under strong influence of the overshielding as well as the convection electric fields. The electric fields on the day- and night sides are in opposite direction to each other, but the electric fields in the evening are anomalously enhanced in the same direction as in the day. The evening anomaly is a unique feature of the electric potential distribution in the global ionosphere. DP2-type electric field and currents develop during the transient/short-term geomagnetic disturbances like the geomagnetic sudden commencements (SC), which appear simultaneously at high latitude and equator within the temporal resolution of 10 s. Using the SC, we can confirm that the electric potential and currents are transmitted near-instantaneously to low latitude ionosphere on both day- and night

  16. Large scale renewable power generation advances in technologies for generation, transmission and storage

    CERN Document Server

    Hossain, Jahangir

    2014-01-01

    This book focuses on the issues of integrating large-scale renewable power generation into existing grids. The issues covered in this book include different types of renewable power generation along with their transmission and distribution, storage and protection. It also contains the development of medium voltage converters for step-up-transformer-less direct grid integration of renewable generation units, grid codes and resiliency analysis for large-scale renewable power generation, active power and frequency control and HVDC transmission. The emerging SMES technology for controlling and int

  17. Current knowledge of sand fly fauna (Diptera: Psychodidae) of northwestern Yemen and how it relates to leishmaniasis transmission.

    Science.gov (United States)

    El Sawaf, Bahira M; Kassem, Hala A; Mogalli, Nabil M; El Hossary, Shabaan S; Ramadan, Nadia F

    2016-10-01

    This report presents the results of the first entomological survey of the sand fly fauna in northwestern Yemen. Sand flies were collected using sticky paper traps and CDC light traps from Hajjah governorate, a cutaneous leishmaniasis focus due to Leishmania tropica. Six Phlebotomus species: P. alexandri, P. arabicus. P. bergeroti, P. orientalis, P. papatasi, P. sergenti and ten Sergentomyia species: S. africana, S. antennata, S. christophersi, S. dolichopa, S. dreyfussi, S. fallax, S. multidens, S. taizi, S. tiberiadis, S. yusafi were identified. P. alexandri was the most predominant Phlebotomus species and P. papatasi was a scarce species. S. fallax was the principal Sergentomyia species and S. dolichopa was the least species encountered. The diversity of the sand fly fauna within and among three altitudinal ranges using Simpson index and Jaccard's diversity coefficient respectively were measured. High species diversity was found in all altitude ranges. There seemed to be more association between sand fly fauna in higher altitudes with fauna from moderate altitudes. Sand fly seasonal activity showed a mono-modal trend in the lowland and a confluent bimodal trend in the highlands. Leishmania DNA could not be detected from 150 Phlebotomus females using PCR-RFLP. A possible zoonotic cutaneous transmission cycle due to Leishmania tropica in northwestern Yemen would involve P. arabicus as the sand fly vector and the rock hyrax as the reservoir host. The vector competence for P. alexandri as a vector of visceral leishmaniasis in Hajjah governorate is discussed.

  18. The Way of Reducing Current Values in Optical Ground Wires at Asymmetrical Faults on Overhead Transmission Lines

    Directory of Open Access Journals (Sweden)

    Egamnazarov Georgiy

    2016-12-01

    Full Text Available Given the fact that the installing costs of an optical ground wire on overhead lines directly depend on its cross-section, which in turn depends on the level of fault current it should withstand, in order to reduce these current values in the optical ground wire, I suggested performing its isolated descents from the end towers of the line with its transition to an optical cable. The research was carried out on the example of a 500 kV overhead line in the National Electric Power Grid. The Method of Symmetrical Components for calculating asymmetrical fault currents was not used; therefore, calculations were carried out on the base of presenting the line as a multi-wire system for the considered case as a five-wire system (optical ground wire, steel ground wire, and three phase wires. Such approach allows taking into account the initial asymmetry of the line parameters and modeling any kind of asymmetrical faults. The analyses of calculated results were performed. The conclusive evidence that the optical ground wire isolated descents from the end towers of the line give the possibility of reducing the level of maximal fault current distribution values in it and therefore its cross section, is presented.

  19. Research on Converter of Offshore Wind Energy Flexible Direct Current Transmission%海上风电柔性直流输电变流器研究

    Institute of Scientific and Technical Information of China (English)

    王志新; 李响; 刘文晋

    2008-01-01

    简要分析海上风电柔性直流输电技术应用及变流器关键技术特点,设计基于柔性高压直流(HVDC)输电的风力发电机集中控制并网变流器主电路拓扑结构.基于电流峰值控制的三电平直流升压变换器双梯形波补偿方法.并利用滞环宽度可调的滞环比较器进行电流跟踪控制.仿真研究表明,该方法具有变流器功率管开关频率固定、减少开关应力及开关损耗、提高传输效率的特点,有助于减少开关器件电压应力和电抗器电流脉动值,提高系统运行的稳定性和可靠性.

  20. Chagas disease: current epidemiological trends after the interruption of vectorial and transfusional transmission in the Southern Cone countries

    Directory of Open Access Journals (Sweden)

    Alvaro Moncayo

    2003-07-01

    Full Text Available Chagas disease, named after Carlos Chagas who first described it in 1909, exists only on the American Continent. It is caused by a parasite, Trypanosoma cruzi, transmitted to humans by blood-sucking triatomine bugs and by blood transfusion. Chagas disease has two successive phases, acute and chronic. The acute phase lasts 6 to 8 weeks. After several years of starting the chronic phase, 20% to 35% of the infected individuals, depending on the geographical area will develop irreversible lesions of the autonomous nervous system in the heart, esophagus, colon and the peripheral nervous system. Data on the prevalence and distribution of Chagas disease improved in quality during the 1980's as a result of the demographically representative cross-sectional studies carried out in countries where accurate information was not available. A group of experts met in Brasília in 1979 and devised standard protocols to carry out countrywide prevalence studies on human T. cruzi infection and triatomine house infestation. Thanks to a coordinated multi-country program in the Southern Cone countries the transmission of Chagas disease by vectors and by blood transfusion has been interrupted in Uruguay in1997, in Chile in 1999, and in 8 of the 12 endemic states of Brazil in 2000 and so the incidence of new infections by T. cruzi in the whole continent has decreased by 70%. Similar control multi-country initiatives have been launched in the Andean countries and in Central America and rapid progress has been recorded to ensure the interruption of the transmission of Chagas disease by 2005 as requested by a Resolution of the World Health Assembly approved in 1998. The cost-benefit analysis of the investments of the vector control program in Brazil indicate that there are savings of US$17 in medical care and disabilities for each dollar spent on prevention, showing that the program is a health investment with good return. Since the inception in 1979 of the Steering

  1. 向无源网络供电的MMC-HVDC送端交流故障穿越策略%AC Fault Ride-Through Strategy of MMC-HVDC Connected to Passive Networks

    Institute of Scientific and Technical Information of China (English)

    肖亮; 徐政; 刘昇; 安婷; 孔明

    2016-01-01

    向无源网络供电的模块化多电平换流器型高压直流输电( MMC-HVDC)系统的送端交流系统发生故障时,功率传输的不平衡会使MMC-HVDC直流电压严重跌落直至系统崩溃。首先分析了送端交流系统发生故障时MMC电容放电的机理,然后设计了一种向无源网络供电的MMC-HVDC送端交流故障穿越策略,该策略的核心思想是在送端故障期间降低无源网络吸收的功率从而使MMC-HVDC直流侧功率尽量平衡。最后在PSCAD/EMTDC仿真平台上搭建了向由感应电动机和静态特性负荷组成的无源网络供电的MMC-HVDC系统,验证了送端系统故障时MMC电容放电机理。仿真结果表明,在所设计的故障穿越策略的作用下,MMC-HVDC在送端交流系统故障期间能够遏制直流电压跌落而保持稳定运行,提高了系统的故障穿越能力。%When there is a severe ground fault in AC grid,the modular multilevel converter high voltage direct current( MMC-HVDC)system connected to passive networks will collapse due to the continuous decline of the DC voltage caused by the imbalanced power transfer. Firstly,the discharging mechanism of the capacitors in the MMC is analyzed. Then an AC fault ride-through strategy of the MMC-HVDC system connected to passive networks is proposed,the key of which is to make a balance between the DC power flowing into and out of the MMC-HVDC system through reducing the power absorbed by the passive networks during the fault. Finally,an MMC-HVDC system connected to passive networks, including induction motors and static load models, is established in the PSCAD/EMTDC software, based on which the discharging mechanism of capacitors in the MMC under the condition of ground fault in AC grid is verified. The simulation results demonstrate that,with the help of the proposed fault ride-through strategy,the drop of the DC voltage is mitigated and the MMC-HVDC system operates steadily during the ground fault in

  2. Signature of the Collaboration agreement contract between CERN and IASS on High Current, Long Distance Superconducting Power Transmission Lines signed Dr.Steve Myers Director of Acc Tech and Prof. Carlo Rubbia.

    CERN Multimedia

    Maximilien Brice

    2012-01-01

    Signature of the Collaboration agreement contract between CERN and IASS on High Current, Long Distance Superconducting Power Transmission Lines signed Dr.Steve Myers Director of Acc Tech and Prof. Carlo Rubbia.

  3. Steady-state modeling of current loss in a post-hole convolute driven by high power magnetically insulated transmission lines

    Science.gov (United States)

    Madrid, E. A.; Rose, D. V.; Welch, D. R.; Clark, R. E.; Mostrom, C. B.; Stygar, W. A.; Cuneo, M. E.; Gomez, M. R.; Hughes, T. P.; Pointon, T. D.; Seidel, D. B.

    2013-12-01

    Quasiequilibrium power flow in two radial magnetically insulated transmission lines (MITLs) coupled to a vacuum post-hole convolute is studied at 50TW-200TW using three-dimensional particle-in-cell simulations. The key physical dimensions in the model are based on the ZR accelerator [D. H. McDaniel, et al., Proceedings of 5th International Conference on Dense Z-Pinches, edited by J. Davis (AIP, New York, 2002), p. 23]. The voltages assumed for this study result in electron emission from all cathode surfaces. Electrons emitted from the MITL cathodes upstream of the convolute cause a portion of the MITL current to be carried by an electron sheath. Under the simplifying assumptions made by the simulations, it is found that the transition from the two MITLs to the convolute results in the loss of most of the sheath current to anode structures. The loss is quantified as a function of radius and correlated with Poynting vector stream lines which would be followed by individual electrons. For a fixed MITL-convolute geometry, the current loss, defined to be the difference between the total (i.e. anode) current in the system upstream of the convolute and the current delivered to the load, increases with both operating voltage and load impedance. It is also found that in the absence of ion emission, the convolute is efficient when the load impedance is much less than the impedance of the two parallel MITLs. The effects of space-charge-limited (SCL) ion emission from anode surfaces are considered for several specific cases. Ion emission from anode surfaces in the convolute is found to increase the current loss by a factor of 2-3. When SCL ion emission is allowed from anode surfaces in the MITLs upstream of the convolute, substantially higher current losses are obtained. Note that the results reported here are valid given the spatial resolution used for the simulations.

  4. ±500kV贵广直流输电系统空载加压试验分析%Analysis on ±500 kV Gui-Guang HVDC System Open Line Test

    Institute of Scientific and Technical Information of China (English)

    邓文斌; 王世荣; 朱俊; 罗斌

    2012-01-01

    UHVDC transmission system because of its large transmission capacity,long distance,low loss,the transmission lines just positive and negative poles lines,simple structure, small site area etc,at present in our country has been more and more widely used. This paper,from the general provisions of the no-load energization test and start wiring way, this paper expounds the principle of HVDC flow changing and open voltage calculation equation of. According to ± 500 kV Gui-Guang HVDC transmission system bipolar no-load energization test, compares pole 1 and pole 2 test data,draw the conclusion,there are certain asymmetry in pole 1 and 2 DC transmission lines after a long time operation, the control mode of pole 1 and 2 affects firing angle.%超高压直流输电系统由于其输送容量大、距离长、损耗小,输电线路只需正负两极线路,杆塔结构简单,占地面积小等优点,目前在中国已经得到越来越广泛的应用.笔者从空载加压试验的一般规定及接线方式开始,阐述了直流输电的换流原理及开路电压计算公式的推导.针对±500 kV贵广直流输电系统双极空载加压试验,比较分析极1和极2的试验数据后,得出结论,极1与极2的直流输电线路在长时间运行后存在一定的不对称性,极1与极2的控制方式影响触发角.

  5. Grid-connection of offshore wind farms using VSC-HVDC systems

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Xiaofan; Dessaint, Louis A. [Ecole de Technologie Superieure, Montreal, QC (Canada). Dept. of Electrical Engineering; Gagnon, Richard [Hydro-Quebec Research Institute, Montreal, QC (Canada)

    2011-07-01

    In this paper, the structure of variable speed PMSG-based offshore wind farms connected to the grid through VSC-HVDC link is presented. And the system models are developed. Also, the corresponding control strategy for this system is proposed. The control objective of the generator side VSC is to achieve the optimal wind power by adjusting the speed of permanent magnet synchronous generator, while the grid side VSC is to maintain DC voltage constant. Furthermore, a case study of 100MW offshore wind farm consisting of 50 individual 2MW PSMG-based wind turbines is developed in MATLAB/SimPowerSystems. Simulation results show the proposed scheme works well. (orig.)

  6. Integration of a finite element generator model into a simulated HVDC connected system

    Energy Technology Data Exchange (ETDEWEB)

    Preston, T.W.; Sturgess, J.P. [GEC Alsthom Engineering Research Center, Stafford (United Kingdom)

    1994-12-31

    Within most system analysis programs generators and motors are represented by an equivalent circuit model either a 2-axis model for both stators and rotor or a three-phase model of the stator and a two-axis model of the rotor. This may be adequate under certain operating conditions such as steady-state or some symmetrical faults but for inverter-fed motors or generators feeding into a rectified load a more rigorous model of the machine is required. This paper describes the theory and development of such a model, its integration with the power electronics and application to 6-pulse and 12-pulse converters, the latter being appropriate in systems similar to HVDC unit connection. (author) 5 refs., 16 figs.

  7. Disturbance Attenuation of DC Voltage Droop Control Structures in a Multi-Terminal HVDC Grid

    DEFF Research Database (Denmark)

    Thams, Florian; Chatzivasileiadis, Spyros; Prieto-Araujo, Eduardo

    2017-01-01

    of the disturbance rejection of these droop control structures. The approach is based on multi-variable frequency response analysis where both ac and dc grid dynamics are incorporated. In particular, the amplification of dc voltage oscillations due to wind power variations is analyzed using singular value analysis......DC voltage droop control is seen as the preferred control structure for primary voltage control of future multiterminal HVDC systems. Different droop control structures have been proposed in literature which can be classified in eight categories. This paper contributes to an analysis....... Further, the impact of dc cable modeling on the results is discussed. In addition, it is shown that the maximum singular value limits, frequently used in literature for MIMO-analysis, are not sufficient to prove that the impact of certain disturbances on analyzed outputs is within a certain boundary...

  8. Current Field Calculation of Cirque UHVDC Transmission Grounding Electrode%特高压直流输电圆环型接地极电流场计算

    Institute of Scientific and Technical Information of China (English)

    徐韬; 徐政; 张哲任; 周志超; 沈扬

    2012-01-01

    In the process of designing an UHVDC transmission grounding electrode, the current field should be calculated. As a result, we introduced a current field calculating method for cirque UHVDC transmission grounding electrode based on resistance network model. Firstly, the grounding electrode field was divided into a certain number of cells in 3D space, and each cell was equivalent to a node in the system, with 6 resistances connecting to adjacent cells; Then, by connecting all the nodes, a resistance network was formed, thus the current field could be calculated by solving the network; Finally, node voltage of the network was acquired and relevant parameters of current field was presented on the basis of node voltage, such as step voltage, current density, etc. Under the same conditions, the calculated results of current field were compared with those by the ANSYS simulation, showing a good consistency, thus, the validity of the resistance network method was verified.%在特高压直流(UHVDC)输电接地极设计过程中,需要对接地极附近的电流场进行计算。为此,介绍了基于电阻网络模型的高压直流输电圆环型接地极电流场的计算方法。首先将接地极场域在三维空间内分割为若干单元,每个单元等效为系统中的1个节点,通过6个等值电阻与相邻单元节点连接;然后将所有单元节点相互连接,构成1个电阻网络,从而将电流场计算问题转化为对电阻网络的求解问题;最后求解电阻网络,得到节点电压,并根据节点电压计算跨步电压、溢流密度等电流场相关参数。在同等条件下,将该算法与ANSYS仿真得到的电流场计算结果进行对比,结果偏差较小,验证了该算法的正确性。

  9. Studies about the current carrying capacity of the devices of the electric power transmission depending on the ambient conditions; Untersuchungen zur Strombelastbarkeit der Geraete der Elektroenergieuebertragung unter Freiluftatmosphaere

    Energy Technology Data Exchange (ETDEWEB)

    Berg, Ina

    2011-07-01

    Due to the liberalization of the electricity market and the increasing expansion of the generation of wind power the transport of electric power in the power grid is increasing. Due to that the electrical equipment is loaded higher up to its thermal limits. However the electrical power supply should be anytime reliable. Because the new construction and upgrade of overhead lines and substations is expensive and approval procedures can take up to ten years, solutions have to be found, to ensue in short and medium term the transport of electrical power through the power grid. In this paper a possibility is introduced and analyzed to increase the current carrying capacity of the electrical equipment without carrying out extensive reconstructions or new buildings. For that the method of thermal networks is used. For the different devices of the electric power transmission (overhead lines, electrical fittings, circuit-breaker, disconnecting switch and current transformer) thermal networks are designed. The heating on examples of all devices was studied and tested under laboratory conditions and the thermal networks were verified. By expansion of the thermal networks with elements for forced convection (wind velocity) and additional heat sources (solar radiation) the ambient conditions were considered. With the help of the so expanded thermal networks parameter studies depending on the wind velocity, ambient temperature and solar radiation were carried out. The studies showed that depending on the ambient conditions the current carrying capacity of all devices can be increased without changing the devices. The rated currents of all devices are specified for a high ambient temperature (e.g. 35 C) and low wind speed (e.g. 1 m/s). Most of the time in a year the ambient temperature is lower and the wind speed is higher than the specified values. So the devices can carry a higher current than the rated current without exceeding its thermal limits. The calculations show the

  10. Transmission of HIV Drug Resistance and the Predicted Effect on Current First-line Regimens in Europe.

    Science.gov (United States)

    Hofstra, L Marije; Sauvageot, Nicolas; Albert, Jan; Alexiev, Ivailo; Garcia, Federico; Struck, Daniel; Van de Vijver, David A M C; Åsjö, Birgitta; Beshkov, Danail; Coughlan, Suzie; Descamps, Diane; Griskevicius, Algirdas; Hamouda, Osamah; Horban, Andrzej; Van Kasteren, Marjo; Kolupajeva, Tatjana; Kostrikis, Leondios G; Liitsola, Kirsi; Linka, Marek; Mor, Orna; Nielsen, Claus; Otelea, Dan; Paraskevis, Dimitrios; Paredes, Roger; Poljak, Mario; Puchhammer-Stöckl, Elisabeth; Sönnerborg, Anders; Staneková, Danica; Stanojevic, Maja; Van Laethem, Kristel; Zazzi, Maurizio; Zidovec Lepej, Snjezana; Boucher, Charles A B; Schmit, Jean-Claude; Wensing, Annemarie M J; Puchhammer-Stockl, E; Sarcletti, M; Schmied, B; Geit, M; Balluch, G; Vandamme, A-M; Vercauteren, J; Derdelinckx, I; Sasse, A; Bogaert, M; Ceunen, H; De Roo, A; De Wit, S; Echahidi, F; Fransen, K; Goffard, J-C; Goubau, P; Goudeseune, E; Yombi, J-C; Lacor, P; Liesnard, C; Moutschen, M; Pierard, D; Rens, R; Schrooten, Y; Vaira, D; Vandekerckhove, L P R; Van den Heuvel, A; Van Der Gucht, B; Van Ranst, M; Van Wijngaerden, E; Vandercam, B; Vekemans, M; Verhofstede, C; Clumeck, N; Van Laethem, K; Beshkov, D; Alexiev, I; Lepej, S Zidovec; Begovac, J; Kostrikis, L; Demetriades, I; Kousiappa, I; Demetriou, V; Hezka, J; Linka, M; Maly, M; Machala, L; Nielsen, C; Jørgensen, L B; Gerstoft, J; Mathiesen, L; Pedersen, C; Nielsen, H; Laursen, A; Kvinesdal, B; Liitsola, K; Ristola, M; Suni, J; Sutinen, J; Descamps, D; Assoumou, L; Castor, G; Grude, M; Flandre, P; Storto, A; Hamouda, O; Kücherer, C; Berg, T; Braun, P; Poggensee, G; Däumer, M; Eberle, J; Heiken, H; Kaiser, R; Knechten, H; Korn, K; Müller, H; Neifer, S; Schmidt, B; Walter, H; Gunsenheimer-Bartmeyer, B; Harrer, T; Paraskevis, D; Hatzakis, A; Zavitsanou, A; Vassilakis, A; Lazanas, M; Chini, M; Lioni, A; Sakka, V; Kourkounti, S; Paparizos, V; Antoniadou, A; Papadopoulos, A; Poulakou, G; Katsarolis, I; Protopapas, K; Chryssos, G; Drimis, S; Gargalianos, P; Xylomenos, G; Lourida, G; Psichogiou, M; Daikos, G L; Sipsas, N V; Kontos, A; Gamaletsou, M N; Koratzanis, G; Sambatakou, H; Mariolis, H; Skoutelis, A; Papastamopoulos, V; Georgiou, O; Panagopoulos, P; Maltezos, E; Coughlan, S; De Gascun, C; Byrne, C; Duffy, M; Bergin, C; Reidy, D; Farrell, G; Lambert, J; O'Connor, E; Rochford, A; Low, J; Coakely, P; O'Dea, S; Hall, W; Mor, O; Levi, I; Chemtob, D; Grossman, Z; Zazzi, M; de Luca, A; Balotta, C; Riva, C; Mussini, C; Caramma, I; Capetti, A; Colombo, M C; Rossi, C; Prati, F; Tramuto, F; Vitale, F; Ciccozzi, M; Angarano, G; Rezza, G; Kolupajeva, T; Vasins, O; Griskevicius, A; Lipnickiene, V; Schmit, J C; Struck, D; Sauvageot, N; Hemmer, R; Arendt, V; Michaux, C; Staub, T; Sequin-Devaux, C; Wensing, A M J; Boucher, C A B; van de Vijver, D A M C; van Kessel, A; van Bentum, P H M; Brinkman, K; Connell, B J; van der Ende, M E; Hoepelman, I M; van Kasteren, M; Kuipers, M; Langebeek, N; Richter, C; Santegoets, R M W J; Schrijnders-Gudde, L; Schuurman, R; van de Ven, B J M; Åsjö, B; Kran, A-M Bakken; Ormaasen, V; Aavitsland, P; Horban, A; Stanczak, J J; Stanczak, G P; Firlag-Burkacka, E; Wiercinska-Drapalo, A; Jablonowska, E; Maolepsza, E; Leszczyszyn-Pynka, M; Szata, W; Camacho, R; Palma, C; Borges, F; Paixão, T; Duque, V; Araújo, F; Otelea, D; Paraschiv, S; Tudor, A M; Cernat, R; Chiriac, C; Dumitrescu, F; Prisecariu, L J; Stanojevic, M; Jevtovic, Dj; Salemovic, D; Stanekova, D; Habekova, M; Chabadová, Z; Drobkova, T; Bukovinova, P; Shunnar, A; Truska, P; Poljak, M; Lunar, M; Babic, D; Tomazic, J; Vidmar, L; Vovko, T; Karner, P; Garcia, F; Paredes, R; Monge, S; Moreno, S; Del Amo, J; Asensi, V; Sirvent, J L; de Mendoza, C; Delgado, R; Gutiérrez, F; Berenguer, J; Garcia-Bujalance, S; Stella, N; de Los Santos, I; Blanco, J R; Dalmau, D; Rivero, M; Segura, F; Elías, M J Pérez; Alvarez, M; Chueca, N; Rodríguez-Martín, C; Vidal, C; Palomares, J C; Viciana, I; Viciana, P; Cordoba, J; Aguilera, A; Domingo, P; Galindo, M J; Miralles, C; Del Pozo, M A; Ribera, E; Iribarren, J A; Ruiz, L; de la Torre, J; Vidal, F; Clotet, B; Albert, J; Heidarian, A; Aperia-Peipke, K; Axelsson, M; Mild, M; Karlsson, A; Sönnerborg, A; Thalme, A; Navér, L; Bratt, G; Karlsson, A; Blaxhult, A; Gisslén, M; Svennerholm, B; Bergbrant, I; Björkman, P; Säll, C; Mellgren, Å; Lindholm, A; Kuylenstierna, N; Montelius, R; Azimi, F; Johansson, B; Carlsson, M; Johansson, E; Ljungberg, B; Ekvall, H; Strand, A; Mäkitalo, S; Öberg, S; Holmblad, P; Höfer, M; Holmberg, H; Josefson, P; Ryding, U

    2016-03-01

    Numerous studies have shown that baseline drug resistance patterns may influence the outcome of antiretroviral therapy. Therefore, guidelines recommend drug resistance testing to guide the choice of initial regimen. In addition to optimizing individual patient management, these baseline resistance data enable transmitted drug resistance (TDR) to be surveyed for public health purposes. The SPREAD program systematically collects data to gain insight into TDR occurring in Europe since 2001. Demographic, clinical, and virological data from 4140 antiretroviral-naive human immunodeficiency virus (HIV)-infected individuals from 26 countries who were newly diagnosed between 2008 and 2010 were analyzed. Evidence of TDR was defined using the WHO list for surveillance of drug resistance mutations. Prevalence of TDR was assessed over time by comparing the results to SPREAD data from 2002 to 2007. Baseline susceptibility to antiretroviral drugs was predicted using the Stanford HIVdb program version 7.0. The overall prevalence of TDR did not change significantly over time and was 8.3% (95% confidence interval, 7.2%-9.5%) in 2008-2010. The most frequent indicators of TDR were nucleoside reverse transcriptase inhibitor (NRTI) mutations (4.5%), followed by nonnucleoside reverse transcriptase inhibitor (NNRTI) mutations (2.9%) and protease inhibitor mutations (2.0%). Baseline mutations were most predictive of reduced susceptibility to initial NNRTI-based regimens: 4.5% and 6.5% of patient isolates were predicted to have resistance to regimens containing efavirenz or rilpivirine, respectively, independent of current NRTI backbones. Although TDR was highest for NRTIs, the impact of baseline drug resistance patterns on susceptibility was largest for NNRTIs. The prevalence of TDR assessed by epidemiological surveys does not clearly indicate to what degree susceptibility to different drug classes is affected. © The Author 2015. Published by Oxford University Press for the Infectious

  11. (PFC) converters feeding brushless DC motor drive

    African Journals Online (AJOL)

    DR OKE

    harmonic distortion (THD) of supply current at AC mains for a wide range of ... An uncontrolled diode bridge rectifier (DBR) with high value of DC link ...... ac transmission systems), HVDC (High voltage direct current) transmission systems. Prof.

  12. Topology of Connecting Photovoltaic Power Station to Power Grid via VSC-HVDC and Its Control Strategy%光伏电站经VSC-HVDC并网拓扑及其控制策略

    Institute of Scientific and Technical Information of China (English)

    赵伟然; 李光辉; 何国庆; 石文辉; 徐青山

    2012-01-01

    In allusion to the mismatch between photovoltaic (PV) station and DC voltage class of voltage source converter-high voltage direct current (VSC-HVDC) system, a new topology of connecting PV station to power grid via VSC-HVDC and corresponding control strategy were proposed. The operational characteristics of PV station in the proposed grid-connecting scheme was researched and the control strategy for single PV generation unit and fault tolerant control strategy for the branch composed of cascade connected PV generation units were analyzed; to solve the problem that in the proposed topological structure the efficiency of cascade connected PV generation units was easy to be affected by unbalanced irradiance, an improved control strategy of voltage slope at DC side of voltage source converter (VSC) was put forward. The proposed control strategies were simulated under several typical irradiation conditions, and simulation results showed that the proposed control strategies were effective.%针对光伏发电与电压源换流器高压直流输电(voltage source converter-high voltage direct current,VSC-HVDC)系统直流电压等级不匹配问题,提出了一种新的光伏电站经VSC-HVDC并网拓扑和控制策略,研究了该并网方案中光伏电站的运行特性,分析了单个光伏发电单元的控制策略和串联光伏发电单元支路故障控制策略;针对该拓扑结构中串联光伏发电单元效率易受不均匀辐照度影响的问题,提出了改进的电压源换流器(voltage source converter,VSC)直流侧电压斜率控制策略.在几种典型辐射情况下进行仿真,结果验证了所提控制策略的有效性,表明该方案可解决VSC-HVDC技术应用于光伏发电并网所面临的电压等级匹配问题.

  13. Avian mortalities due to transmission line collisions: a review of current estimates and field methods with an emphasis on applications to the Canadian electric network

    Directory of Open Access Journals (Sweden)

    Sébastien Rioux

    2013-12-01

    Full Text Available Birds are vulnerable to collisions with human-made fixed structures. Despite ongoing development and increases in infrastructure, we have few estimates of the magnitude of collision mortality. We reviewed the existing literature on avian mortality associated with transmission lines and derived an initial estimate for Canada. Estimating mortality from collisions with power lines is challenging due to the lack of studies, especially from sites within Canada, and due to uncertainty about the magnitude of detection biases. Detection of bird collisions with transmission lines varies due to habitat type, species size, and scavenging rates. In addition, birds can be crippled by the impact and subsequently die, although crippling rates are poorly known and rarely incorporated into estimates. We used existing data to derive a range of estimates of avian mortality associated with collisions with transmission lines in Canada by incorporating detection, scavenging, and crippling biases. There are 231,966 km of transmission lines across Canada, mostly in the boreal forest. Mortality estimates ranged from 1 million to 229.5 million birds per year, depending on the bias corrections applied. We consider our most realistic estimate, taking into account variation in risk across Canada, to range from 2.5 million to 25.6 million birds killed per year. Data from multiple studies across Canada and the northern U.S. indicate that the most vulnerable bird groups are (1 waterfowl, (2 grebes, (3 shorebirds, and (4 cranes, which is consistent with other studies. Populations of several groups that are vulnerable to collisions are increasing across Canada (e.g., waterfowl, raptors, which suggests that collision mortality, at current levels, is not limiting population growth. However, there may be impacts on other declining species, such as shorebirds and some species at risk, including Alberta's Trumpeter Swans (Cygnus buccinator and western Canada's endangered Whooping

  14. Applications of high-temperature superconductors in power technology[8470 High-current and high-voltage technology: power systems; power transmission lines and cables;

    Energy Technology Data Exchange (ETDEWEB)

    Hull, John R [Energy Technology Division, Argonne National Laboratory, Argonne, IL 60439 (United States)

    2003-11-01

    Since the discovery of the first high-temperature superconductors (HTSs) in the late 1980s, many materials and families of materials have been discovered that exhibit superconductivity at temperatures well above 20 K. Of these, several families of HTSs have been developed for use in electrical power applications. Demonstration of devices such as motors, generators, transmission lines, transformers, fault-current limiters, and flywheels in which HTSs and bulk HTSs have been used has proceeded to ever larger scales. First-generation wire, made from bismuth-based copper oxides, was used in many demonstrations. The rapid development of second-generation wire, made by depositing thin films of yttrium-based copper oxide on metallic substrates, is expected to further accelerate commercial applications. Bulk HTSs, in which large single-grain crystals are used as basic magnetic components, have also been developed and have potential for electrical power applications.

  15. Microstructure changes during non-conventional heat treatment of thin Ni-Ti wires by pulsed electric current studied by transmission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Delville, R., E-mail: remi.delville@ua.ac.be [EMAT, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); Malard, B.; Pilch, J.; Sittner, P. [Institute of Physics, Na Slovance 2, 182 21 Praha (Czech Republic); Schryvers, D. [EMAT, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium)

    2010-08-15

    Transmission electron microscopy, electrical resistivity measurements and mechanical testing were employed to investigate the evolution of microstructure and functional superelastic properties of 0.1 mm diameter as-drawn Ni-Ti wires subjected to a non-conventional heat treatment by controlled electric pulse currents. This method enables a better control of the recovery and recrystallization processes taking place during the heat treatment and accordingly a better control on the final microstructure. Using a stepwise approach of millisecond pulse annealing, it is shown how the microstructure evolves from a severely deformed state with no functional properties to an optimal nanograined microstructure (20-50 nm) that is partially recovered through polygonization and partially recrystallized and that has the best functional properties. Such a microstructure is highly resistant against dislocation slip upon cycling, while microstructures annealed for longer times and showing mostly recrystallized grains were prone to dislocation slip, particularly as the grain size exceeds 200 nm.

  16. Effect of induced shielding current transmission in longitudinal direction on levitation force of melt grown single-domain YBa2Cu3O7-x cylindrical superconductor

    Institute of Scientific and Technical Information of China (English)

    YANG Wanmin; ZHOU Lian; FENG Yong; ZHANG Pingxiang; R.Nicolsky; R.de Andrade Jr

    2004-01-01

    A novel layer deletion method is used to experimentally investigate the effect of induced shielding current transmission (ISCT) in the longitudinal direction on the levitation force of a single-domain YBa2Cu3O7-x (YBCO) cylindrical superconductor (φ30x7 mm). In the experiment the sample was gradually sliced into two equal sheets, at the middle height along a diameter with 5 mm every step. The experimental results show that the levitation force is closely related with the ISCT in the longitudinal direction. Any layer deletion, even a small piece of layer deletion can reduce the levitation force of the sample. After the whole layer was deleted the levitation force can diminish about 50%. It is also found that the levitation force is directly proportional to the effective factor of surface area, which is equal to the top surface area divided by the total surface area parallel to the top surface of the sample.

  17. Naval Open Architecture Machinery Control Systems for Next Generation Integrated Power Systems

    Science.gov (United States)

    2012-05-01

    Step-Down Converters for High Voltage Direct Current ( HVDC ) Transmission Systems Zonal Electrical Distribution Systems For NGIPS, multifunction...Transmission ( HVDC ),  Distributed Generation, and  Energy Storage applications. The focus was on high power applications ranging from one to

  18. AN ASSESSMENT OF HIGH-VOLTAGE DC ELECTRICAL POWER IN AIRCRAFT ELECTRICAL SYSTEMS.

    Science.gov (United States)

    If the presently installed three-phase ac transmission system on aircraft were replaced by a higher voltage dc ( HVDC ) transmission using a ground...from one- to two-thirds of the total electrical system weight. HVDC may have some disadvantages such as higher short-circuit currents, some increase in

  19. 高肇直流融冰运行模式下无功功率和谐波特性分析%Analysis on Reactive Power and Harmonics of Gao-Zhao HVDC Under Deicing Operation Mode

    Institute of Scientific and Technical Information of China (English)

    谢惠藩; 王海军; 陈潜

    2011-01-01

    为研究高肇(高坡一肇庆)直流融冰模式、正常模式的无功特性和谐波特性,基于EMTDC搭建了±500kV高肇直流背靠背融冰详细模型并重点针对融冰模式、正常模式下换流站的无功特性和交直流侧谐波特性进行仿真研究。仿真结果表明:高坡站融冰模式的无功消耗比正常模式略大,肇庆站融冰模式的无功消耗则比正常模式略小;融冰模式下换流站交流谐波电流幅值比正常模式小、畸变率比正常模式大,而交流谐波电压及其畸变率均比正常模式小;融冰模式下同一换流站中两极处于不同的运行状态,两极直流侧谐波特性不相同。该研究结果为高肇直流在融冰方式下滤波器的投切提供一定的理论指导。%To study the characteristics of reactive power and harmonic of Gao-Zhao high voltage direct current (HV[)C) under deicing operation mode and normal operation mode, an EMTDC model of ~500 kV C-ao-Zhao HVDC with direct current power forth-and reverse transmission deicing function is introduced in detail. With this model the characteristics of reactive power and harmonic at converter station are analyzed. Simulations show that: (1) Reactive power consumption at Gaopo converter station under deicing operation mode is larger than that under normal operation mode, while Zhaoqing converter station is on the contrary; (2) The amplitude of harmonic alternative current is smaller and total harmonic current distortion rate is larger compared to the normal operation mode, and the amplitude and harmonic distortion rate of alternative current voltage are both smaller than that of normal operation mode; (3) The two poles operating at different modes and the harmonic in direct system of each pole in the same converter station is different. Simulation results are helpful to the control of alternative current filter control under deicing operation mode.

  20. Linealización de sistemas VSC-HVDC para el diseño de un controlador PI vectorial

    Directory of Open Access Journals (Sweden)

    Nelson Díaz Aldana

    2014-01-01

    Full Text Available Los sistemas VSC-HVDC son muy utilizados para la transmisión de energía en redes de interconexión eléctrica. Uno de los principales problemas que poseen estos sistemas es la complejidad de su modelo matemático, lo que conlleva grandes dificultades para el diseño de controladores que permitan la regulación de parámetros como la tensión DC de transmisión, así como la potencia activa y reactiva del sistema VSC-HVDC. En este artículo se presenta la linealización de un sistema VSC-HVDC y el posterior diseño de un controlador lineal PI vectorial a partir del modelo linealizado. Adicionalmente, se proponen dos estrategias para la validación de este tipo de controladores, la primera consiste en un único controlador PI para regular los estados del sistema para cada VSC, la segunda consiste en el diseño de controladores PI vectoriales independientes para la regulación de cada estado del VSC.

  1. A Control Strategy for Modular Multilevel Converter Based HVDC of Unbalanced AC Systems%不对称交流电网下MMC-HVDC输电系统的控制策略

    Institute of Scientific and Technical Information of China (English)

    孔明; 汤广福; 贺之渊; 杨杰

    2013-01-01

    The power fluctuation under asymmetric AC voltages caused the sub-module energy unbalance for modular multilevel converters, which thereby affected the dynamic characteristics of the MMC-HVDC system. By analyzing the arm instantaneous power of MMC, the control targets of the sub-module capacitor voltage and the circulating current were determined. On this basis, a control strategy composing of the sub-module capacitor voltage predicted based the nearest level modulation and circulating current predicted based direct circulating current control was presented. Whether the AC system is symmetrical or not, under the proposed control strategy, the voltages of sub-module capacitor each arm were kept balanced relatively, and the fundamental frequency and the second harmonic of the circulating current were suppressed. A MMC-HVDC simulation model of two ends was established based on PSCAD/EMTDC. The simulations under the asymmetric AC grid for the active power and the DC voltage control station were conducted respectively. Simulation results show that the proposed control strategy could keep the average value of the sub-module capacitor voltage remain constant during the AC system asymmetric fault, and avoid the DC voltage fluctuation caused by the zero sequence instantaneous power, which thereby improves the fault ride-through capability of the system.%不对称交流电网下的功率波动将引起模块化多电平换流器子模块能量的不平衡,进而影响模块化多电平变流器型高压直流输电(modular multilevel converter based HVDC, MMC-HVDC)的动态性能。基于不对称交流电网下MMC桥臂瞬时功率的分析,确定换流器内部子模块电容电压及桥臂环流的控制目标。在此基础上,提出一种基于子模块电容电压预估的最近电平调制和基于桥臂环流预估的直接环流控制,两者相结合的复合控制策略。不论交流系统对称与否,在所提出的控制策略下,均能保证换

  2. Steady-state modeling of current loss in a post-hole convolute driven by high power magnetically insulated transmission lines

    Directory of Open Access Journals (Sweden)

    E. A. Madrid

    2013-12-01

    Full Text Available Quasiequilibrium power flow in two radial magnetically insulated transmission lines (MITLs coupled to a vacuum post-hole convolute is studied at 50  TW–200  TW using three-dimensional particle-in-cell simulations. The key physical dimensions in the model are based on the ZR accelerator [D. H. McDaniel, et al., Proceedings of 5th International Conference on Dense Z-Pinches, edited by J. Davis (AIP, New York, 2002, p. 23]. The voltages assumed for this study result in electron emission from all cathode surfaces. Electrons emitted from the MITL cathodes upstream of the convolute cause a portion of the MITL current to be carried by an electron sheath. Under the simplifying assumptions made by the simulations, it is found that the transition from the two MITLs to the convolute results in the loss of most of the sheath current to anode structures. The loss is quantified as a function of radius and correlated with Poynting vector stream lines which would be followed by individual electrons. For a fixed MITL-convolute geometry, the current loss, defined to be the difference between the total (i.e. anode current in the system upstream of the convolute and the current delivered to the load, increases with both operating voltage and load impedance. It is also found that in the absence of ion emission, the convolute is efficient when the load impedance is much less than the impedance of the two parallel MITLs. The effects of space-charge-limited (SCL ion emission from anode surfaces are considered for several specific cases. Ion emission from anode surfaces in the convolute is found to increase the current loss by a factor of 2–3. When SCL ion emission is allowed from anode surfaces in the MITLs upstream of the convolute, substantially higher current losses are obtained. Note that the results reported here are valid given the spatial resolution used for the simulations.

  3. 基于负序电压补偿的VSC-HVDC系统的不平衡控制%Unbalanced control strategy based on negative voltage compensation for VSC-HVDC system

    Institute of Scientific and Technical Information of China (English)

    杨硕; 张卫星; 李德泉

    2012-01-01

    交流系统故障时VSC-HVDC系统的控制策略直接关系到系统的运行和安全性能,具有明显的工程应用价值.建立了交流系统不平衡故障时d-q同步旋转坐标系下系统换流器的正负序数学模型,设计了不平衡条件下的同步相位和正负序分量的实时检测系统.采用非线性系统反馈线性化理论,设计了系统的状态反馈线性化电流解耦控制器.在此基础上设计了负序电压补偿的不平衡控制系统,在有效抑制负序电流的同时,简化了控制系统结构.基于PSIM的数字仿真,验证了所设计的控制器具有良好的控制性能.%The control strategy for unbalanced VSC-HVDC system is directly related to its function and security, so it has a great importance for the engineering. The paper builds a positive and negative mathematical model of VSC in d-q synchronous reference frame, and designs a detecting system of synchronous phase and positive and negative component under unbalanced condition. By using nonlinear transformation and nonlinear system feedback linearization theory, the state-feedback linearization decoupling controller for VSC-HVDC system is established. Finally, the paper designs an unbalanced control strategy based on negative voltage compensation for VSC-HVDC. Besides restraining the negative current, it also simplifies the structure of the control system. The digital simulation based on PSIM proves the designed controller has good control performance.

  4. Fundamental analysis and development of the current and voltage control method by changing the driving frequency for the transcutaneous energy transmission system.

    Science.gov (United States)

    Miura, Hidekazu; Yamada, Akihiro; Shiraishi, Yasuyuki; Yambe, Tomoyuki

    2015-08-01

    We have been developing transcutaneous energy transmission system (TETS) for a ventricular assist device, shape memory alloy (SMA) fibered artificial organs and so on, the system has high efficiency and a compact size. In this paper, we summarize the development, design method and characteristics of the TETS. New control methods for stabilizing output voltage or current of the TETS are proposed. These methods are primary side, are outside of the body, not depending on a communication system from the inside the body. Basically, the TETS operates at the fixed frequency with a suitable compensation capacitor so that the internal impedance is minimalized and a flat load characteristic is obtained. However, when the coil shifted from the optimal position, the coupling factor changes and the output is fluctuated. TETS has a resonant property; its output can be controlled by changing the driving frequency. The continuous current to continuous voltage driving method was implemented by changing driving frequency and setting of limitation of low side frequency. This method is useful for battery charging system for electrically driven artificial hearts and also useful for SMA fibered artificial organs which need intermittent high peak power comsumption. In this system, the internal storage capacitor is charged slowly while the fibers are turned off and discharge the energy when the fibers are turned on. We examined the effect of the system. It was found that the size and maximum output of the TETS would able to be reduced.

  5. Power Management of Small Naval Vessels

    Science.gov (United States)

    2011-08-31

    Reference [16] and [6] explains the current differential scheme employed in SPS and HVDC systems respectively. Other schemes presently employed in DC...2002.985003 [3] Jiebei Zhu; Booth, C;, "Future multi-terminal HVDC transmission systems using Voltage source converters," Universities Power Engineering...Delivery, IEEE Transactions on , vol.25, no.4, pp.2308-2318, Oct. 2010 doi: 10.1109/TPWRD.2010.2044813 [6] Naidoo, D.; Ijumba, N.M.;, " HVDC line

  6. VSC—HVDC在风电场并网系统中的应用研究%A survey of VSC - HVDC for wind farm interconnection

    Institute of Scientific and Technical Information of China (English)

    肖小兵; 周杰娜; 袁旭峰; 姚刚; 何肖蒙

    2012-01-01

    介绍风力发电并网对电网产生的影响,分析说明VSC—HVDC的工作原理和技术特点,并对风电场联网VSC—HVDC控制器设计进行阐述,列举VSC~HVDC的应用场合,并且举例介绍国外采用VSC—HVDC在风电并网中的应用。%The impact of the wind farm interconnection is described, then the working principle and the technical characteristics of VSC - HVDC are analyzed and explained, and then the design of the wind farm interconnection with VSC - HVDC controller is described, finally a list of application in VSC - HVDC controll on wind farm intergration is listed together with illustrated examples.

  7. 高压直流输电入地电流在交流电网分布的仿真分析%Simulation and Analysis of HVDC Earth-return Current's Distribution in AC Power Grid

    Institute of Scientific and Technical Information of China (English)

    潘卓洪; 张露; 谭波; 梅桂华; 文习山

    2011-01-01

    DC bias of neutral-earthing transformers is caused by earth-return current of high voltage direct current(HVDC) transmission.Using the data of power flow calculations and by building the mathematical model,computer aided analysis of DC distribution can be carried out.This approach is introduced to obtain the DC distribution and DC restrain measure of Chu-Sui ultra HVDC transmission of Guangdong power grid.Through the study,the rules of DC distribution in some random virtual power grids can be obtained.It can be concluded that more DC distribution will be resulted with larger scale power grid and more geographically concentrated distribution substations.Errors between the calculation and realistic measurement are caused by the errors in resistances of transformer windings and neutral reactor.It is observed that DC distribution of 220 kV networks is affected by the neutral-earthing 110 kV networks,but this is not the case for 500 kV systems.Utilizing neutral braking measure will lead to increment of DC distribution in local power grid,but the total amount will be reduced. This work is supported by Special Fund of the National Basic Research Program of China(No.2009CB724500).%高压直流输电入地电流可能造成中性点接地运行变压器出现直流偏磁现象。借助潮流计算数据整理电网信息,再通过建立数学模型,可以有效地开展直流分布的计算机仿真工作。介绍了仿真软件在楚穗直流调试工况下预测和抑制广东电网直流分布的应用,最后通过随机算法产生的虚拟电网算例分析总结了电网参数对直流分布的影响:交流电网规模越大,变电站越密集,直流分布越严重;变压器和中性点小电抗准确阻值难以完全统计,仿真计算结果与实际值会存在一定偏差;接地运行的110kV系统会影响220kV网络的直流分布,但500kV系统的直流分布则基本不变;采用中性点抑制措施后,电网局部直流分布会增加,但电网直流电流总量下降。

  8. Application of an Improved PSO-based PID Neural Network Controller for VSC-HVDC%基于改进粒子群算法的PIDNN控制器在VSC-HVDC中的应用

    Institute of Scientific and Technical Information of China (English)

    李爽; 王志新; 王国强

    2013-01-01

    An improved niche chaotic particle swarm optimization (INCPSO) method for voltage source converter based high-voltage direct-current (VSC-HVDC) system was presented. It emerges the good features of niche and chaotic mutation evolutionary algorithms for searching the global best parameters of proportional-integral-derivative neural-network (PIDNN). With the introduction of restricted competition selection (RCS) method into the niche mechanism, the global exploration ability of PSO is enhanced. Simultaneously, the precise local exploitation performance can be well achieved by using the chaotic mutation algorithm with tent-mapping functions. The INCPSO can solve the premature phenomenon and local convergence problem of traditional PSO, and give a balance point between the exploration and exploitation capability. The detail steps of parameters optimizing for PIDNN controller in VSC-HVDC system was presented, and a numerical example was carried out to validate the feasibility and effectiveness of INCPSO. Simulation results show that the INCPSO search capability is more accurate, effective and robust. The INCPSO based PIDNN controller provides a feasible control scheme in the offshore wind farm VSC-HVDC system.%针对海上风电场并网柔性直流输电(voltage source converter based high-voltage direct-current,VSC-HVDC)系统比例-积分-微分神经网络(PID neural network,PIDNN)控制器参数寻优过程中存在的问题,提出一种基于限制竞争小生境混沌变异的改进粒子群算法(improved niche· chaotic particle swarm optimization,INCPSO).该算法中小生境技术引入限制竞争淘汰机制,使其具有良好的全局寻优能力(探索),配合改进的帐篷映射混沌变异算法,可获得局部精细遍历性能(发现).在解决粒子群算法早熟收敛和搜索精度低等问题的同时,最大程度地平衡了粒子群算法在解空间内的探索和发现能力.给出了VSC-HVDC系统中PIDNN控制器参数寻优INCPSO算法

  9. Three-Dimensional Nanometer Features of Direct Current Electrical Trees in Low-Density Polyethylene.

    Science.gov (United States)

    Pallon, Love K H; Nilsson, Fritjof; Yu, Shun; Liu, Dongming; Diaz, Ana; Holler, Mirko; Chen, Xiangrong R; Gubanski, Stanislaw; Hedenqvist, Mikael S; Olsson, Richard T; Gedde, Ulf W

    2017-03-08

    Electrical trees are one reason for the breakdown of insulating materials in electrical power systems. An understanding of the growth of electrical trees plays a crucial role in the development of reliable high voltage direct current (HVDC) power grid systems with transmission voltages up to 1 MV. A section that contained an electrical tree in low-density polyethylene (LDPE) has been visualized in three dimensions (3D) with a resolution of 92 nm by X-ray ptychographic tomography. The 3D imaging revealed prechannel-formations with a lower density with the width of a couple of hundred nanometers formed around the main branch of the electrical tree. The prechannel structures were partially connected with the main tree via paths through material with a lower density, proving that the tree had grown in a step-by-step manner via the prestep structures formed in front of the main channels. All the prechannel structures had a size well below the limit of the Paschen law and were thus not formed by partial discharges. Instead, it is suggested that the prechannel structures were formed by electro-mechanical stress and impact ionization, where the former was confirmed by simulations to be a potential explanation with electro-mechanical stress tensors being almost of the same order of magnitude as the short-term modulus of low-density polyethylene.

  10. VSC-HVDC的次同步阻尼特性研究%Study on sub-synchronous damping characteristic of VSC-HVDC

    Institute of Scientific and Technical Information of China (English)

    徐坤; 赵成勇; 高本锋

    2012-01-01

    目前针对基于电压源换流器(Voltage Source Converter)的高压直流输电技术(VSC-HVDC)的研究,主要集中在控制策略方面,而研究VSC-HVDC对相邻发电机组阻尼特性的影响较少.从VSC-HVDC的工作原理出发,阐述了VSC-HVDC的能够抑制次同步振荡的机理.采用基于时域实现的复转矩系数法-测试信号法,分析了机组作用系数、控制方式以及有功、无功功率水平对VSC-HVDC阻尼特性的影响.针对同一交流系统,对比分析了VSC-HVDC与传统的HVDC的阻尼特性的大小.研究结果表明,与传统HVDC相比,VSC-HVDC能够显著改善相邻发电机组的次同步阻尼特性.%The study on the HVDC based on voltage-source converter focuses mainly on the control strategy while less on the impact of electrical damping on the adjacent units by VSC-HVDC. The mechanism of VSC-HVDC on inhibiting sub-synchronous oscillation is analyzed theoretically in the respect of its operation principle. Then the complex torque coefficient method, namely the test signal method, which is realized by time domain simulation, is adopted to investigate the impact of the unit interaction factor, control mode, active power level and reactive power level on the electrical damping on the adjacent units. Finally, adopting the same system, the damping of VSC-HVDC and HVDC are compared using test signal method.

  11. 基于Simulink & PSB的高压直流输电系统建模仿真%Modeling High Voltage Direct Current Transmission System Based on Simulink and PSB

    Institute of Scientific and Technical Information of China (English)

    刘淑军; 吴成明

    2004-01-01

    对高压直流输电系统(HVDC)控制器动态性能的研究是建立在HVDC系统模型之上的.采用Matlab中的PSB工具箱对HVDC系统建模,利用Simulink建立HVDC变参数PID控制器,通过分析和仿真表明,这种建模方法有效,并且与常规PID控制器相比,变参数PID控制器在对HVDC系统的控制上表现出较好的适应性和控制效果.

  12. Interaction of Droop Control Structures and its Inherent Effect on the Power Transfer Limits in Multi-terminal VSC-HVDC

    DEFF Research Database (Denmark)

    Thams, Florian; Eriksson, Robert; Molinas, M.

    2016-01-01

    Future multi-terminal HVDC systems are expected to utilize dc voltage droop controllers and several control structures have been proposed in literature. This paper proposes a methodology to analyse the impact of various types of droop control structures using small-signal stability analysis...... to disturbances for all the implementations. A case study analyzing a three terminal HVDC VSC-based grid with eight different kinds of droop control schemes points out that three control structures outperform the remaining ones. Additionally, a multi-vendor case is considered where the most beneficial...

  13. Summarization for Development and Application Status of HVDC Technology%HVDC技术的发展应用情况综述

    Institute of Scientific and Technical Information of China (English)

    赵国梁; 吴涛

    2006-01-01

    HVDC(高压直流输电)技术在我国具有广阔的应用前景.本文对HVDC的特点及其发展应用情况,我国HVDC工程建设的国产化情况,HVDC在我国的应用前景,以及多端HVDC、轻型HVDC和电容换相换流器(CCC)等新型HVDC技术的发展应用情况进行综述.

  14. A Study on the Application for Enhancing the Transmission Capability of the KEPCO Power System

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Young Han; Kwon, Tea Won; Whang, Jong Young; Lee, Gun Joon; Kim, Tae Hoon; Chang, Byung Hoon; Min, Wan Ki [Korea Electric Power Research Institute, Taejon (Korea, Republic of); Park, Young Moon; Park, Jong Gun [Seoul National University, Seoul (Korea, Republic of); Kim, Gun Joong [Chungnam National University, Taejon (Korea, Republic of); Oh, Tae Kwu; Choi, Kwu Hyung [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1996-12-31

    Investigation of stability for power system in 2000 year and 2006 year by using the analysis of real power system. Comparative investigation of the conventional transmission line upgrading methods such as HVDC, HOP, new conductor scheme. Investigation of FACTS, the recent transmission line upgrading method, with respect to the aspect of technique and cost and effect analysis when this method is applied to real power system. Development of the evaluation method of transmission type that should be considered when above method is applied to real power system with respect to aspect of technique and cost. Development of a long-range plan for the transmission capacity upgrading and the evaluation method of reliability. (author).

  15. Total Transfer Capability Calculation for Regional Power Systems with HVDC Connected with Large Scale Wind Power%大规模风电经直流外送的区域输电能力计算

    Institute of Scientific and Technical Information of China (English)

    刘杨; 周明; 向萌; 张紫凡

    2013-01-01

    大型风电基地风电消纳的可行方案是跨区域直接送至负荷中心进行消化,由此产生大规模风电远距离输电的问题,进而对区域间最大输电能力(Total Transfer Capability,TTC)的计算提出新需求.针对大规模风电经直流外送的区域输电能力计算,结合风火打捆直流外送方式,建立了风电经直流外送的区域间TTC计算模型,并采用交直流交替迭代连续潮流算法进行求解.采用改进的IEEE 39节点系统进行测试,对大规模风电经交、直流2种外送方式下的TTC进行对比计算,并讨论了不同风电场出力情况及风火打捆比例对TTC的影响.结果表明:在既定网架结构下,需要协调考虑风火打捆比例和线路容量,在尽可能多地接纳风电的同时,使系统获得最大输电能力.%For the digestion of wind power generated in the large wind power bases, the feasible option is transferring the power to the load center directly cross regions, yet the new transfer format gives rise to the long distance power transmission of the large wind farms, which necessitates new demands for calculation of the total transfer capability (TTC) across regions. Aiming at the calculation of the TTC of the trans -regional HVDC transmission system for large-sized wind farms, and based on the format of the bundled transmission format of both thermal and wind power, this paper establishes a TTC calculation model considering that wind power delivered to another region by HVDC and uses the continuation power flow (CPF) algorithm based on AC/DC alternate iteration to find solutions. The modified IEEE 39 —bus system is used for the test, the TTC through AC and HVDC paths is calculated respectively and the influence of the wind power output and wind/fire bundling ratio is also discussed. The results indicate that under the established grid structure, it's necessary to consider wind fire bundling proportion and line capacity coordinately to ensure the system can

  16. Phylogeography of Yersinia ruckeri reveals effects of past evolutionary events on the current strain distribution and explains variations in the global transmission of Enteric Redmouth (ERM disease.

    Directory of Open Access Journals (Sweden)

    Asmine eBastardo

    2015-10-01

    Full Text Available Phylogeographic patterns and population genetic structure of Yersinia ruckeri, the pathological agent of enteric redmouth disease (ERM in salmonids, were investigated on the basis of concatenated multiloci sequences from isolates of different phenotypes obtained between 1965-2009 from diverse areas and hosts. Sequence analyses revealed genetic differentiation among subpopulations with the largest genetic distance occurring between subpopulations of Europe and Canada and/or South America. Bayesian analysis indicated the presence of three ancestral population clusters. Mismatch distribution displayed signatures characteristic of changes in size due to demographic and spatial expansions in the overall Y. ruckeri population, and also in the geographically separate subpopulations. Furthermore, a weak signal of isolation by distance was determined. A significant positive correlation between genetic and geographical distances was observed. These results revealed that the population of Y. ruckeri has undergone both ancient and recent population changes that were probably induced by biogeography forces in the past and, much more recently, by adaptive processes forced by aquaculture expansion. These findings have important implications for future studies on Y. ruckeri population dynamics, on the potential role of genetic structure to explain variations in ERM transmission, and on the effect of past evolutionary events on current estimations of gene flow.

  17. Development of toroid-type HTS DC reactor series for HVDC system

    Science.gov (United States)

    Kim, Kwangmin; Go, Byeong-Soo; Park, Hea-chul; Kim, Sung-kyu; Kim, Seokho; Lee, Sangjin; Oh, Yunsang; Park, Minwon; Yu, In-Keun

    2015-11-01

    This paper describes design specifications and performance of a toroid-type high-temperature superconducting (HTS) DC reactor. The first phase operation targets of the HTS DC reactor were 400 mH and 400 A. The authors have developed a real HTS DC reactor system during the last three years. The HTS DC reactor was designed using 2G GdBCO HTS wires. The HTS coils of the toroid-type DC reactor magnet were made in the form of a D-shape. The electromagnetic performance of the toroid-type HTS DC reactor magnet was analyzed using the finite element method program. A conduction cooling method was adopted for reactor magnet cooling. The total system has been successfully developed and tested in connection with LCC type HVDC system. Now, the authors are studying a 400 mH, kA class toroid-type HTS DC reactor for the next phase research. The 1500 A class DC reactor system was designed using layered 13 mm GdBCO 2G HTS wire. The expected operating temperature is under 30 K. These fundamental data obtained through both works will usefully be applied to design a real toroid-type HTS DC reactor for grid application.

  18. 660 kV直流输电线路带电作业研究%Research on the Live-line Operation of 660 kV DC Transmission Lines

    Institute of Scientific and Technical Information of China (English)

    张志峰; 王永豪

    2015-01-01

    根据我国直流输电线路特点以及银东直流输电线路山西段运行维护的实际情况,并结合我国及世界各国关于直流输电的研究成果及50余年来输电线路带电作业经验,对±660 kV直流超高压输电线路带电作业的基础研究、作业人员的安全防护、防护用具、作业方式、作业工具等进行了论述,指出了当前应开展的工作,以保证±660 kV直流输电线路的安全稳定运行。%According to the characteristics of China's DC transmission line and the operation and maintenance situation of Yindong DC transmission line in Shanxi, and combining with the research achievements on DC transmission home and abroad and the live-line working experience in recent 50 years, some issues concerning live-line operation of ±660 kV HVDC transmission lines are elaborated, including basic research about live-line operation, operators' safety protection, protective equipment, operation mode and live-line tools etc.. The work that should be carried out currently are pointed out to ensure the safe and stable operation of ± 660 kV DC transmission lines.

  19. Adaptive controller design based on input-output signal selection for voltage source converter high voltage direct current systems to improve power system stability

    Institute of Scientific and Technical Information of China (English)

    Abdolkhalegh Hamidi; Jamal Beiza; Ebrahim Babaei; Sohrab Khanmohammadi

    2016-01-01

    An input-output signal selection based on Phillips-Heffron model of a parallel high voltage alternative current/high voltage direct current (HVAC/HVDC) power system is presented to study power system stability. It is well known that appropriate coupling of inputs-outputs signals in the multivariable HVDC-HVAC system can improve the performance of designed supplemetary controller. In this work, different analysis techniques are used to measure controllability and observability of electromechanical oscillation mode. Also inputs–outputs interactions are considered and suggestions are drawn to select the best signal pair through the system inputs-outputs. In addition, a supplementary online adaptive controller for nonlinear HVDC to damp low frequency oscillations in a weakly connected system is proposed. The results obtained using MATLAB software show that the best output-input for damping controller design is rotor speed deviation as out put and phase angle of rectifier as in put. Also response of system equipped with adaptive damping controller based on HVDC system has appropriate performance when it is faced with faults and disturbance.

  20. 输电线两端均带并联电抗器的纵联差动保护%Research on Current Differential Protection at Both Ends of Transmission Line with Shunt Reactor Circuit

    Institute of Scientific and Technical Information of China (English)

    杨俊武; 杨明玉; 徐诚; 武历忠

    2016-01-01

    When it is applied on UHV transmission lines, traditional current differential protection will be seriously affected by distributed capacitive current of transmission line .The traditional methods of capacitive current compensation is not still effective enough. So a novel principle of segregated current phase differential protection at both ends of transmission line with shunt reactor circuit based on the Bergeron model is proposed. The principle is to calculate based on Bergeron model and compare the currents of two sides of selected reference point on the protected transmission line. It will not be affected by distributed capacitive current and is more sensitive and reliable than traditional segregated current phase differential protection. Simulation results by MATLAB conifrm that the principle is correct and has best rapid when used on UHV transmission lines.%针对特高压输电线路分布电容电流较大,传统的电容电流补偿方法没有好效果,的问题,提出了在两端均接有并联电抗器的长距离输电线上应用贝瑞隆模型实现分相电流差动保护新原理,该原理实现方法是应用贝瑞隆模型计算参考点两侧的电流并进行差动计算,与基于电容电流补偿方法的传统分相电流差动保护相比,该原理不受分布电容电流的影响,具有更高的可靠性和灵敏性,用Matlab仿真证明了该原理正确性和用于特高压线路的快速性。