WorldWideScience

Sample records for voltage ac power

  1. Impacts on Power Factor of AC Voltage Controllers Under Non-Sinusoidal Conditions

    Directory of Open Access Journals (Sweden)

    Mukhtiar Ahmed Mahar

    2012-04-01

    Full Text Available AC-AC conversion is obtained with the help of Cyclo-converters, DC Link converters and AC Voltage Controllers. AC voltage controllers are also referred to as voltage regulators. Main issue concerned to these converters is that they generate harmonics due to periodic variable structure system. The generated harmonics create disturbances and degrade the performance of converter. The power factor of supply side is affected due to these harmonics. This paper focuses on source side power factor of ac voltage controllers under nonsinusoidal conditions. In order to observe the power factor, measurement tool of power factor and simulation model of ac voltage controller is also developed in MATLAB software.

  2. Solid-state fast voltage compensator for pulsed power applications requiring constant AC power consumption

    CERN Document Server

    Magallanes, Francisco Cabaleiro; Viarouge, Philippe; Cros, Jérôme

    2015-01-01

    This paper proposes a novel topological solution for pulsed power converters based on capacitor-discharge topologies, integrating a Fast Voltage Compensator which allows an operation at constant power consumption from the utility grid. This solution has been retained as a possible candidate for the CLIC project under study at CERN, which requires more than a thousand synchronously-operated klystron modulators producing a total pulsed power of almost 40 GW. The proposed Fast Voltage Compensator is integrated in the modulator such that it only has to treat the capacitor charger current and a fraction of the charging voltage, meaning that its dimensioning power and cost are minimized. This topology can be used to improve the AC power quality of any pulsed converters based on capacitor-discharge concept. A prototype has been built and exploited to validate the operating principle and demonstrate the benefits of the proposed solution.

  3. High Voltage AC underground cable systems for power transmission

    DEFF Research Database (Denmark)

    Bak, Claus Leth; Silva, Filipe Miguel Faria da

    2016-01-01

    This paper is a second of two presenting a review of research results in underground cable transmission obtained by the Department of Energy Technology, Aalborg University ET/AAU and Danish TSO Energinet.dk within the last six years. The main core of the results are obtained by PhD students...... researching electrical engineering topics related to using underground cables for power transmission at EHV level and including the 420 kV level. The research topics were laid down by ET/AAU and Energinet.dk in the DANPAC (DANish Power systems with Ac Cables) research project. The main topics are discussed...

  4. A Study on Power Quality Improvement in PWM Controlled AC Voltage Controller

    Directory of Open Access Journals (Sweden)

    Ahmet ALTINTAŞ

    2009-04-01

    Full Text Available A lot of topologies of pulse-width modulated (PWM-AC controllers for single-phase and three-phase systems are proposed up to date. PWM-AC controllers have important advantages compared with the phase-controlled AC controllers using thyristors and triacs. The PWM-AC controller has sinusoidal current waveforms, smaller THD values, better power factor, faster dynamics, and smaller input/output filter. This article presents a novel control technique for application to PWM-AC controllers with ability of generating fewer harmonics. In the proposed control method, both the traditional AC voltage controllers and the PWM-AC controllers are combined; and smaller THD values are obtained. Thus, the harmonic pollution in the power system will be reduced; and consequently, the power quality will be increased. For this purpose, computer simulations are performed in order to investigate the proposed controller performance. The obtained results are compared with the conventional PWM-AC controller.

  5. High Voltage AC underground cable systems for power transmission

    DEFF Research Database (Denmark)

    Bak, Claus Leth; Silva, Filipe Miguel Faria da

    2016-01-01

    This paper is a first of two presenting a review of research results in underground cable transmission obtained by the Department of Energy Technology, Aalborg University ET/AAU and Danish TSO Energinet.dk within the last 6 years. The main core of the results are obtained by PhD students research......This paper is a first of two presenting a review of research results in underground cable transmission obtained by the Department of Energy Technology, Aalborg University ET/AAU and Danish TSO Energinet.dk within the last 6 years. The main core of the results are obtained by PhD students...... researching electrical engineering topics related to using underground cables for power transmission at EHV level and including the 420 kV level. The research topics were laid down by ET/AAU and Energinet.dk in the DANPAC (DANish Power systems with AC Cables) research project. The main topics are discussed...

  6. DC Voltage Droop Control Implementation in the AC/DC Power Flow Algorithm: Combinational Approach

    DEFF Research Database (Denmark)

    Akhter, F.; Macpherson, D.E.; Harrison, G.P.

    2015-01-01

    In this paper, a combinational AC/DC power flow approach is proposed for the solution of the combined AC/DC network. The unified power flow approach is extended to include DC voltage droop control. In the VSC based MTDC grids, DC droop control is regarded as more advantageous in terms...... of operational flexibility, as more than one VSC station controls the DC link voltage of the MTDC system. This model enables the study of the effects of DC droop control on the power flows of the combined AC/DC system for steady state studies after VSC station outages or transient conditions without needing...... to use its complete dynamic model. Further, the proposed approach can be extended to include multiple AC and DC grids for combined AC/DC power flow analysis. The algorithm is implemented by modifying the MATPOWER based MATACDC program and the results shows that the algorithm works efficiently....

  7. 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...

  8. Advanced power electronics converters PWM converters processing AC voltages

    CERN Document Server

    dos Santos, Euzeli

    2014-01-01

    This book covers power electronics, in depth, by presenting the basic principles and application details, which can be used both as a textbook and reference book.  Introduces a new method to present power electronics converters called Power Blocks Geometry. Applicable for courses focusing on power electronics, power electronics converters, and advanced power converters. Offers a comprehensive set of simulation results to help understand the circuits presented throughout the book

  9. Nonlinear control of voltage source converters in AC-DC power system.

    Science.gov (United States)

    Dash, P K; Nayak, N

    2014-07-01

    This paper presents the design of a robust nonlinear controller for a parallel AC-DC power system using a Lyapunov function-based sliding mode control (LYPSMC) strategy. The inputs for the proposed control scheme are the DC voltage and reactive power errors at the converter station and the active and reactive power errors at the inverter station of the voltage-source converter-based high voltage direct current transmission (VSC-HVDC) link. The stability and robust tracking of the system parameters are ensured by applying the Lyapunov direct method. Also the gains of the sliding mode control (SMC) are made adaptive using the stability conditions of the Lyapunov function. The proposed control strategy offers invariant stability to a class of systems having modeling uncertainties due to parameter changes and exogenous inputs. Comprehensive computer simulations are carried out to verify the proposed control scheme under several system disturbances like changes in short-circuit ratio, converter parametric changes, and faults on the converter and inverter buses for single generating system connected to the power grid in a single machine infinite-bus AC-DC network and also for a 3-machine two-area power system. Furthermore, a second order super twisting sliding mode control scheme has been presented in this paper that provides a higher degree of nonlinearity than the LYPSMC and damps faster the converter and inverter voltage and power oscillations.

  10. Increased deposition of polychlorinated biphenyls (PCBs) under an AC high-voltage power line

    Science.gov (United States)

    Öberg, Tomas; Peltola, Pasi

    2009-12-01

    There is considerable public concern regarding the potential risks to health of electromagnetic fields in general and high-voltage power lines in particular. As epidemiological findings are not supported by a clearly defined mechanism of direct magnetic field interactions with the human body, potential indirect effects are of interest. It has been suggested that an increased exposure to chemical pollutants could occur near high-voltage power lines due to formation and deposition of charged aerosols. The current study reports empirical evidence that seems to support this hypothesis. The deposition of 18 congeners of polychlorinated biphenyls (PCBs) was studied by collecting samples of pine needles under a 400 kV AC power line and at reference sites in the vicinity. Compared to the reference sites, the average deposition of PCB congeners under the power line was almost double. This difference between the two groups of samples was statistically significant. While it is premature to draw any conclusions regarding the human exposure near high-voltage power lines, the issue deserves attention and further investigations.

  11. Active Power and DC-link Voltage Coordinative Control for Cascaded DC-AC Converter with Bidirectional Power Application

    DEFF Research Database (Denmark)

    Tian, Yanjun; Chen, Zhe; Deng, Fujin;

    2015-01-01

    Two stage cascaded converters are widely used in DC/AC hybrid systems to achieve the bidirectional power transmission. The topology of dual active bridge cascaded with inverter (DABCI) is commonly used in this application. This paper proposes a coordinative control method for DABCI and it’s able...... to reduce the DC-link voltage fluctuation between the DAB and inverter, then reduce the stress on the switching devices, as well as improve the system dynamic performance. In the proposed control method, the DAB and inverter are coordinated to control the DC-link voltage and the power......, and this responsibility sharing control can effectively suppress the impact of the power variation on the DC-link voltage, without sacrificing stability. The proposed control method is also effective for DABCI in unidirectional power transmission. The effectiveness of the propose control has been validated by both...

  12. Containment and Consensus-based Distributed Coordination Control for Voltage Bound and Reactive Power Sharing in AC Microgrid

    DEFF Research Database (Denmark)

    Han, Renke; Meng, Lexuan; Ferrari-Trecate, Giancarlo

    2017-01-01

    This paper offers a highly flexible and reliable control strategy to achieve voltage bounded regulation and accurate reactive power sharing coordinately in AC Micro-Grids. A containment and consensus-based distributed coordination controller is proposed, by which each output voltage magnitude can...

  13. Containment and Consensus-based Distributed Coordination Control for Voltage Bound and Reactive Power Sharing in AC Microgrid

    DEFF Research Database (Denmark)

    Han, Renke; Meng, Lexuan; Ferrari-Trecate, Giancarlo

    2017-01-01

    This paper offers a highly flexible and reliable control strategy to achieve voltage bounded regulation and accurate reactive power sharing coordinately in AC Micro-Grids. A containment and consensus-based distributed coordination controller is proposed, by which each output voltage magnitude can...

  14. Shunt capacitors for a.c. power systems having a rated voltage above 1000 V - Part 1: General

    CERN Document Server

    International Electrotechnical Commission. Geneva

    2005-01-01

    This part of IEC 60871 is applicable to both capacitor units and capacitor banks intended to be used, particularly, for power-factor correction of a.c. power systems having a rated voltage above 1 000 V and frequencies of 15 Hz to 60 Hz. This part of IEC 60871 also applies to capacitors intended for use in power filter circuits.

  15. Voltage source ac-to-dc converters for high-power transmitters

    Science.gov (United States)

    Cormier, R.

    1990-01-01

    This work was done to optimize the design of the components used for the beam power supply, which is a component of the transmitters in the Deep Space Network (DSN). The major findings are: (1) the difference in regulation between a six-pulse and a twelve-pulse converter is at most 7 percent worse for the twelve-pulse converter; (2) the commutation overlap angle of a current source converter equals that of a voltage source converter with continuous line currents; (3) the sources of uncharacteristic harmonics are identified with SPICE simulation; (4) the use of an imperfect phase-shifting transformer for the twelve-pulse converter generates a harmonic at six times the line frequency; and (5) the assumptions usually made in analyzing converters can be relaxed with SPICE simulation. The results demonstrate the suitability of using SPICE simulation to obtain detailed performance predictions of ac-to-dc converters.

  16. Power Balance Control in an AC/DC/AC Converter for Regenerative Braking in a Two-Voltage-Level Flywheel-Based Driveline

    Directory of Open Access Journals (Sweden)

    Janaína G. Oliveira

    2011-01-01

    Full Text Available The integration of a flywheel as a power handling can increase the energy storage capacity and reduce the number of battery charge/discharge cycles. Furthermore, the ability of recovering energy of the vehicle during breaking can increase the system efficiency. The flywheel-based all-electric driveline investigated here has its novelty in the use of a double-wound flywheel motor/generator, which divides the system in two different voltage levels, enhancing the efficiency of the electric driveline. The connection of two AC electrical machines (i.e., the flywheel and the wheel motor with different and variable operation frequency is challenging. A power matching control applied to an AC/DC/AC converter has been implemented. The AC/DC/AC converter regenerates the electric power converted during braking to the flywheel machine, used here as power handling device. By controlling the power balance, the same hardware can be used for acceleration and braking, providing the reduction of harmonics and robust response. A simulation of the complete system during braking mode has been performed both in Matlab and Simulink, and their results have been compared. The functionality of the proposed control has been shown and discussed, with full regeneration achieved. A round-trip efficiency (wheel to wheel higher than 80% has been obtained.

  17. Coordinated Reactive Power and Voltage Management for Offshore Wind Farms with AC-connection

    DEFF Research Database (Denmark)

    Heussen, Kai

    2008-01-01

    This paper analyzes voltage and reactive power in a wind farm in dependence on switchable shunt and tap-changer settings in connection with the control ranges of flexible reactive power sources. Attention is paid to their interdependent effects on central control variables, such as voltage...... in the collection grid, reactive power exported to the grid and internal active power losses. An aggregated steady-state model of an offshore wind farm is presented and a reduced mathematical representation suitable for symbolic analysis is developed. A coordination scheme is proposed to coordinate fast continuous...... control inputs with slow tap-changing devices using a short-term prediction. The proposed scheme is aimed at balancing cost factors such as wear of switching components, active power loss within the wind farm and STATCOM capacity....

  18. Containment and Consensus-based Distributed Coordination Control to Achieve Bounded Voltage and Precise Reactive Power Sharing in Islanded AC Microgrids

    DEFF Research Database (Denmark)

    Han, Renke; Meng, Lexuan; Ferrari-Trecate, Giancarlo

    2017-01-01

    This paper presents a novel distributed approach to achieve both bounded voltage and accurate reactive power sharing regulation in AC microgrid. The coupling/trade-off effects between bus voltages and reactive power sharing regulation are first analyzed in detail to provide a guideline for coordi...

  19. Characteristics of Overvoltage Protection with Cascade Application of Surge Protective Devices in Low-Voltage AC Power Circuits

    Directory of Open Access Journals (Sweden)

    RADULOVIC, V.

    2015-08-01

    Full Text Available Surge Protective Devices (SPDs are widely used for protection of the equipment in low-voltage AC power circuits against wide variety of surges. Cascade application of SPDs starting at the service entrance of a building and downstream toward near sensitive equipment is intended to ensure optimal energy distribution among installed SPDs, as well as proper equipment protection against surges. Characteristics of overvoltage protection with two-stage application of SPDs have been analyzed in the paper through performed measurements, followed by simulations and numerical modeling using the ATP/EMTP and MATLAB Simulink. Parametric analysis of the protection's characteristics in wide range of influencing factors has been performed in order to define a set of applicable solutions for proper selection and performance of SPDs.

  20. Condition assessment of power cables using partial discharge diagnosis at damped AC voltages

    NARCIS (Netherlands)

    Wester, F.J.

    2004-01-01

    The thesis focuses on the condition assessment of the distribution power cables, which have a very critical part in the distribution of electrical power over regional distances. The majority of the outages in the power system is related to the distribution cables, of which for more than 60% to inter

  1. Unbalanced Voltage Compensation in Low Voltage Residential AC Grids

    DEFF Research Database (Denmark)

    Trintis, Ionut; Douglass, Philip; Munk-Nielsen, Stig

    2016-01-01

    This paper describes the design and test of a control algorithm for active front-end rectifiers that draw power from a residential AC grid to feed heat pump loads. The control algorithm is able to control the phase to neutral or phase to phase RMS voltages at the point of common coupling....... The voltage control was evaluated with either active or reactive independent phase load current control. The control performance in field operation in a residential grid situated in Bornholm, Denmark was investigated for different use cases....

  2. Power Flow Analysis for Low-Voltage AC and DC Microgrids Considering Droop Control and Virtual Impedance

    DEFF Research Database (Denmark)

    Li, Chendan; Chaudhary, Sanjay Kumar; Savaghebi, Mehdi

    2017-01-01

    adequate power flow studies. In this paper, power flow analyses for both AC and DC microgrids are formulated and implemented. The mathematical models for both types of microgrids considering the concept of virtual impedance are used to be in conformity with the practical control of the distributed...... generators. As a result, calculation accuracy is improved for both AC and DC microgrid power flow analyses, comparing with previous methods without considering virtual impedance. Case studies are conducted to verify the proposed power flow analyses in terms of convergence and accuracy. Investigation...

  3. Design of a Solid-State Fast Voltage Compensator for klystron modulators requiring constant AC power consumption

    CERN Document Server

    Aguglia, Davide; Viarouge, Philippe; Cros, Jerome

    2014-01-01

    This paper proposes a novel topological solution for klystron modulators integrating a Fast Voltage Compensator which allows an operation at constant power consumption from the utility grid. This kind of solution is mandatory for the CLIC project under study, which requires several hundreds of synchronously operated klystron modulators for a total pulsed power of 39 GW. The topology is optimized for the challenging CLIC specifications, which require a very precise output voltage flat-top as well as fast rise and fall times (3µs). The Fast Voltage Compensator is integrated in the modulator such that it only has to manage the capacitor charger current and a fraction of the charging voltage. Consequently, its dimensioning power and cost is minimized.

  4. DC injection into low voltage AC networks

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2005-07-01

    This report summarises the results of a study investigating the impact of levels of injected DC current injections on a low voltage AC distribution network systems in order to recommend acceptable limits of DC from microgeneration. Relevant literature is reviewed, and the impact of DC levels in distribution transformers, transformer modelling, and instrumental transformers are discussed. The impact of DC in residual current devices (RCD) and in domestic electricity watt hour meters is examined along with DC enhanced corrosion, corrosion failure, and the measurement of DC current injection. Sources of DC injection outlined include DC from computer power supplies, network faults, geomagnetic phenomena, lighting circuits/dimmers, and embedded generators.

  5. Design of wide output voltage AC-DC power supply based on buck-boost circuit%基于Buck-Boost电路的宽输出电压AC-DC电源设计

    Institute of Scientific and Technical Information of China (English)

    徐文城; 刘尧; 王秀荣

    2012-01-01

    设计了一种宽输出电压的AC DC开关电源,其主要特征是输出电压可以在较大范围内任意调节,解决了传统的开关电源只能输出几个特定电压值的问题.该设计的核心是反激变换电路和Buck-Boost电路.分析了这两种电路的工作原理及其应用,并且给出了具体的设计.实验表明,设计的电源能较好地实现了输出电压的宽范围调节.%AC-DC switching power supply with a wide range voltage output was designed. Its main feature is that the output voltage can be adjusted in a wide range. The problem that the traditional switching power supplies only have few specific voltage outputs is solved in the design. The flyback convert circuit and Buck-Boost circuit are the cores of the design. The working principle and applications of these two circuits are analyzed. The concrete design is given in this paper. The experiments show that a wide range regulation of the output voltage has been more successfully achieved in the design of the power supply.

  6. Power sharing algorithm for vector controlled six-phase AC motor with four customary three-phase voltage source inverter drive

    DEFF Research Database (Denmark)

    Padmanaban, Sanjeevikumar; Grandi, Gabriele; Blaabjerg, Frede

    2015-01-01

    This paper considered a six-phase (asymmetrical) induction motor, kept 30 phase displacement between two set of three-phase open-end stator windings configuration. The drive system consists of four classical three-phase voltage inverters (VSIs) and all four dc sources are deliberately kept isolated......) by nearest three vectors (NTVs) approach is adopted to regulate each couple of VSIs. The proposed power sharing algorithm is verified by complete numerical simulation modeling (Matlab/ Simulink-PLECS software) of whole ac drive system by observing the dynamic behaviors in different designed condition. Set...

  7. Power sharing algorithm for vector controlled six-phase AC motor with four customary three-phase voltage source inverter drive

    Directory of Open Access Journals (Sweden)

    Sanjeevikumar Padmanaban

    2015-09-01

    Full Text Available This paper considered a six-phase (asymmetrical induction motor, kept 30° phase displacement between two set of three-phase open-end stator windings configuration. The drive system consists of four classical three-phase voltage inverters (VSIs and all four dc sources are deliberately kept isolated. Therefore, zero-sequence/homopolar current components cannot flow. The original and effective power sharing algorithm is proposed in this paper with three variables (degree of freedom based on synchronous field oriented control (FOC. A standard three-level space vector pulse width modulation (SVPWM by nearest three vectors (NTVs approach is adopted to regulate each couple of VSIs. The proposed power sharing algorithm is verified by complete numerical simulation modeling (Matlab/Simulink-PLECS software of whole ac drive system by observing the dynamic behaviors in different designed condition. Set of results are provided in this paper, which confirms a good agreement with theoretical development.

  8. Cryocooled Josephson standards for AC voltage metrology

    Science.gov (United States)

    Durandetto, P.; Sosso, A.; Monticone, E.; Trinchera, B.; Fretto, M.; Lacquaniti, V.

    2017-05-01

    The Josephson effect is worldwide used as a basis for constant reference voltages in national metrological institutes and in calibration laboratories of industry. Research on Josephson voltage standards is aiming at a fundamental change also in the metrology of the volt for AC and arbitrary waveforms: programmable Josephson voltage standards converting a digital code into a quantum-accurate stepwise waveform are already available in primary laboratories and even more advanced standards for converting sub-nanosecond binary coded pulses into any arbitrary signal with quantum accuracy are now actively developed and tested. A new experimental setup based on a two-stage Gifford-McMahon cryocooler has been developed at INRiM for the operation of AC-Josephson voltage standards. Among its distinct features, the possibility of employing both the aforementioned techniques (programmable and pulsed Josephson voltage standards) is particularly interesting. Quantum-based AC voltage sine waves have been synthesized with both programmable and pulse-driven arrays, although their accuracy is still limited by thermal oscillations due to the cryocooler piston motion.

  9. Modeling of long High Voltage AC Underground

    DEFF Research Database (Denmark)

    Gudmundsdottir, Unnur Stella; Bak, Claus Leth; Wiechowski, W. T.

    2010-01-01

    This paper presents the work and findings of a PhD project focused on accurate high frequency modelling of long High Voltage AC Underground cables. The project is cooperation between Aalborg University and Energinet.dk. The objective of the project is to investigate the accuracy of most up to date...

  10. 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...

  11. Experimental investigation of SDBD plasma actuator driven by AC high voltage with a superimposed positive pulse bias voltage

    Science.gov (United States)

    Qi, Xiao-Hua; Yan, Hui-Jie; Yang, Liang; Hua, Yue; Ren, Chun-Sheng

    2017-08-01

    In this work, a driven voltage consisting of AC high voltage with a superimposed positive pulse bias voltage ("AC+ Positive pulse bias" voltage) is adopted to study the performance of a surface dielectric barrier discharge plasma actuator under atmospheric conditions. To compare the performance of the actuator driven by single-AC voltage and "AC+ Positive pulse bias" voltage, the actuator-induced thrust force and power consumption are measured as a function of the applied AC voltage, and the measured results indicate that the thrust force can be promoted significantly after superimposing the positive pulse bias voltage. The physical mechanism behind the thrust force changes is analyzed by measuring the optical properties, electrical characteristics, and surface potential distribution. Experimental results indicate that the glow-like discharge in the AC voltage half-cycle, next to the cycle where a bias voltage pulse has been applied, is enhanced after applying the positive pulse bias voltage, and this perhaps is the main reason for the thrust force increase. Moreover, surface potential measurement results reveal that the spatial electric field formed by the surface charge accumulation after positive pulse discharge can significantly affect the applied external electric field, and this perhaps can be responsible for the experimental phenomenon that the decrease of thrust force is delayed by pulse bias voltage action after the filament discharge occurs in the glow-like discharge region. The schlieren images further verify that the actuator-induced airflow velocity increases with the positive pulse voltage.

  12. AC Optimal Power Flow

    Energy Technology Data Exchange (ETDEWEB)

    2016-10-04

    In this work, we have implemented and developed the simulation software to implement the mathematical model of an AC Optimal Power Flow (OPF) problem. The objective function is to minimize the total cost of generation subject to constraints of node power balance (both real and reactive) and line power flow limits (MW, MVAr, and MVA). We have currently implemented the polar coordinate version of the problem. In the present work, we have used the optimization solver, Knitro (proprietary and not included in this software) to solve the problem and we have kept option for both the native numerical derivative evaluation (working satisfactorily now) as well as for analytical formulas corresponding to the derivatives being provided to Knitro (currently, in the debugging stage). Since the AC OPF is a highly non-convex optimization problem, we have also kept the option for a multistart solution. All of these can be decided by the user during run-time in an interactive manner. The software has been developed in C++ programming language, running with GCC compiler on a Linux machine. We have tested for satisfactory results against Matpower for the IEEE 14 bus system.

  13. SoC-Based Dynamic Power Sharing Method with AC-Bus Voltage Restoration for Microgrid Applications

    DEFF Research Database (Denmark)

    Lu, Xiaonan; Sun, Kai; Guerrero, Josep M.

    2012-01-01

    In a microgrid system, distributed energy storage units are commonly employed as the energy buffers. In this paper, a dynamic power sharing method based on the state-of-charge (SoC) of each energy storage unit is proposed. Droop control is employed as the basic control strategy for the distributed...... shared in the energy storage system. The relationship between the droop coefficient and SoC are studied deeply and the small signal model is developed to verify the stability of the control system. It is found that the active power sharing speed becomes faster with higher exponent of SoC. At the same...... energy storage units. By using the proposed method, the coefficients in the conventional droop method are adjusted according to the SoC of each energy storage module. The modules with higher SoC delivers more active power, while those with lower SoC delivers less. Meanwhile, the reactive power is equally...

  14. Moderately nonlinear diffuse-charge dynamics under an ac voltage

    Science.gov (United States)

    Stout, Robert F.; Khair, Aditya S.

    2015-09-01

    The response of a symmetric binary electrolyte between two parallel, blocking electrodes to a moderate amplitude ac voltage is quantified. The diffuse charge dynamics are modeled via the Poisson-Nernst-Planck equations for a dilute solution of point-like ions. The solution to these equations is expressed as a Fourier series with a voltage perturbation expansion for arbitrary Debye layer thickness and ac frequency. Here, the perturbation expansion in voltage proceeds in powers of Vo/(kBT /e ) , where Vo is the amplitude of the driving voltage and kBT /e is the thermal voltage with kB as Boltzmann's constant, T as the temperature, and e as the fundamental charge. We show that the response of the electrolyte remains essentially linear in voltage amplitude at frequencies greater than the RC frequency of Debye layer charging, D /λDL , where D is the ion diffusivity, λD is the Debye layer thickness, and L is half the cell width. In contrast, nonlinear response is predicted at frequencies below the RC frequency. We find that the ion densities exhibit symmetric deviations from the (uniform) equilibrium density at even orders of the voltage amplitude. This leads to the voltage dependence of the current in the external circuit arising from the odd orders of voltage. For instance, the first nonlinear contribution to the current is O (Vo3) which contains the expected third harmonic but also a component oscillating at the applied frequency. We use this to compute a generalized impedance for moderate voltages, the first nonlinear contribution to which is quadratic in Vo. This contribution predicts a decrease in the imaginary part of the impedance at low frequency, which is due to the increase in Debye layer capacitance with increasing Vo. In contrast, the real part of the impedance increases at low frequency, due to adsorption of neutral salt from the bulk to the Debye layer.

  15. Performance Analysis of Phase Controlled Unidirectional and Bidirectional AC Voltage Controllers

    Directory of Open Access Journals (Sweden)

    Abdul Sattar Larik

    2011-01-01

    Full Text Available AC voltage controllers are used to vary the output ac voltage from a fixed ac input source. They are also commonly called ac voltage regulators or ac choppers. The output voltage is either controlled by PAC (Phase Angle Control method or on-off control method. Due to various advantages of ac voltage controllers, such as high efficiency, simplicity, low cost and ability to control large amount of power they efficiently control the speed of ac motors, light dimming and industrial heating, etc. These converters are variable structure systems and generate harmonics during the operation which will affect the power quality when connected to system network. During the last couple of years, a number of new semiconductor devices and various power electronic converters has been introduced. Accordingly the subject of harmonics and its problems are of great concern to power industry and customers. In this research work, initially the simulation models of single phase unidirectional and bidirectional ac voltage controllers were developed by using MATLAB software. The harmonics of these models are investigated by simulation. In the end, the harmonics were also analyzed experimentally. The simulated as well as experimental results are presented.

  16. Approaches to building single-stage AC/AC conversion switch-mode audio power amplifiers

    DEFF Research Database (Denmark)

    Ljusev, Petar; Andersen, Michael Andreas E.

    2004-01-01

    This paper discusses the possible topologies and promising approaches towards direct single-phase AC-AC conversion of the mains voltage for audio applications. When compared to standard Class-D switching audio power amplifiers with a separate power supply, it is expected that direct conversion...

  17. Low power DCVSL circuits employing AC power supply

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    In view of changing the type of energy conversion in CMOS circuits, this paper investigates low power CMOS circuit design, which adopts a gradually changing power clock. First, we discuss the algebraic expressions and the corresponding properties of clocked power signals. Then the design procedure is summed up for converting complementary CMOS logic gates employing DC power to the power-clocked CMOS gates employing AC power. On this basis, the design of differential cascode voltage switch logic (DCVSL) circuits employing AC power clocks is proposed. The PSPICE simulations using a sinusoidal power-clock demonstrate that the designed power-clocked DCVSL circuit has a correct logic function and low power characteristics. Finally, an interface circuit to convert clocked signals into the standard logic levels of a CMOS circuit is proposed, and its validity is verified by computer simulations.

  18. Power control for ac motor

    Science.gov (United States)

    Dabney, R. W. (Inventor)

    1984-01-01

    A motor controller employing a triac through which power is supplied to a motor is described. The open circuit voltage appearing across the triac controls the operation of a timing circuit. This timing circuit triggers on the triac at a time following turn off which varies inversely as a function of the amplitude of the open circuit voltage of the triac.

  19. Modular High Voltage Power Supply

    Energy Technology Data Exchange (ETDEWEB)

    Newell, Matthew R. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-05-18

    The goal of this project is to develop a modular high voltage power supply that will meet the needs of safeguards applications and provide a modular plug and play supply for use with standard electronic racks.

  20. Non-isolated DC-AC converter with high voltage gain for autonomous systems of electric power; Conversor CC-CA nao isolado com alto ganho de tensao para aplicacao em sistemas autonomos de energia eletrica

    Energy Technology Data Exchange (ETDEWEB)

    Silveira, George Cajazeiras [Centro Federal de Educacao Tecnologica do Ceara (CEFET/CE), Fortaleza, CE (Brazil); Torrico-Bascope, Rene P. [Universidade Federal do Ceara (PPGEE/UFC), Fortaleza, CE (Brazil). Programa de Pos Graduacao em Engenharia Eletrica; Borges Neto, Manuel Rangel [Centro Federal de Educacao Tecnologica de Petrolina (CEFET-PET), PE (Brazil)

    2008-07-01

    A non-isolated DC-AC converter with high voltage gain with two output sinusoidal voltage - 110 V and 220 V - and frequency 60 Hz for application in autonomous systems of electric power is proposed in this work. This topology consists of a boost converter with high voltage gain, based on three-state switching cell combined with a double half bridge inverter. This configuration type the size and the cost are reduced and the efficiency is gotten better, due to the reduced number of switches. The converters that compose this topology operate with high frequency, reducing the volume of the magnetic materials. can be mention as important characteristics: the voltage stress across the switches of the boost converter are low, due they be naturally clamped by one output filter capacitor, which allows the utilization of switches with lower conduction resistances, and the waveforms of the output voltage of the double half bridge inverter supplies for the load it is sinusoidal and it possesses low harmonic content. (author)

  1. AC power generation from microbial fuel cells

    Science.gov (United States)

    Lobo, Fernanda Leite; Wang, Heming; Forrestal, Casey; Ren, Zhiyong Jason

    2015-11-01

    Microbial fuel cells (MFCs) directly convert biodegradable substrates to electricity and carry good potential for energy-positive wastewater treatment. However, the low and direct current (DC) output from MFC is not usable for general electronics except small sensors, yet commercial DC-AC converters or inverters used in solar systems cannot be directly applied to MFCs. This study presents a new DC-AC converter system for MFCs that can generate alternating voltage in any desired frequency. Results show that AC power can be easily achieved in three different frequencies tested (1, 10, 60 Hz), and no energy storage layer such as capacitors was needed. The DC-AC converter efficiency was higher than 95% when powered by either individual MFCs or simple MFC stacks. Total harmonic distortion (THD) was used to investigate the quality of the energy, and it showed that the energy could be directly usable for linear electronic loads. This study shows that through electrical conversion MFCs can be potentially used in household electronics for decentralized off-grid communities.

  2. An AMOLED AC-Biased Pixel Design Compensating the Threshold Voltage and I-R Drop

    Directory of Open Access Journals (Sweden)

    Ching-Lin Fan

    2011-01-01

    Full Text Available We propose a novel pixel design and an AC bias driving method for active-matrix organic light-emitting diode (AM-OLED displays using low-temperature polycrystalline silicon thin-film transistors (LTPS-TFTs. The proposed threshold voltage and I-R drop compensation circuit, which comprised three transistors and one capacitor, have been verified to supply uniform output current by simulation work using the Automatic Integrated Circuit Modeling Simulation Program with Integrated Circuit Emphasis (AIM-SPICE simulator. The simulated results demonstrate excellent properties such as low error rate of OLED anode voltage variation (<0.7% and low voltage drop of VDD power line. The proposed pixel circuit effectively enables threshold-voltage-deviation correction of driving TFT and compensates for the voltage drop of VDD power line using AC bias on OLED cathode.

  3. An AC/AC Direct Power Conversion Topology Having Multiple Power Grid Connections with Adjustable Loading

    DEFF Research Database (Denmark)

    Klumpner, Christian; Blaabjerg, Frede

    2004-01-01

    Normally, a power converter has one supply port to connect to the power grid and one or multiple output ports to connect to AC loads that require variable voltage and variable frequency. As the trend on the energy market is towards deregulation, new converter topologies are needed to allow...... independent producers/consumers to connect to multiple distribution grids in order to optimise the electricity price, as this will vary during the day from one power distribution company to another one. It will be needed to have a load that can smoothly adjust the power consumed from each power grid in order...... these fraction power will be a necessary feature on a deregulated energy market. This paper presents a new topology of a power converter based on the Direct Power Conversion concept, which is able to connect to multiple grids and provide complete decoupling between without circulating power between the grids...

  4. TRANSISTOR HIGH VOLTAGE POWER SUPPLY

    Science.gov (United States)

    Driver, G.E.

    1958-07-15

    High voltage, direct current power supplies are described for use with battery powered nuclear detection equipment. The particular advantages of the power supply described, are increased efficiency and reduced size and welght brought about by the use of transistors in the circuit. An important feature resides tn the employment of a pair of transistors in an alternatefiring oscillator circuit having a coupling transformer and other circuit components which are used for interconnecting the various electrodes of the transistors.

  5. Strongly nonlinear dynamics of electrolytes in large ac voltages

    DEFF Research Database (Denmark)

    Olesen, Laurits Højgaard; Bazant, Martin Z.; Bruus, Henrik

    2010-01-01

    We study the response of a model microelectrochemical cell to a large ac voltage of frequency comparable to the inverse cell relaxation time. To bring out the basic physics, we consider the simplest possible model of a symmetric binary electrolyte confined between parallel-plate blocking electrodes...... in the electrolyte near the electrodes and, at very large voltage, the breakdown of the quasiequilibrium structure of the double layers. The former leads to the prediction of “ac capacitive desalination” since there is a time-averaged transfer of salt from the bulk to the double layers, via oscillating diffusion...... nonlinear responses to large ac voltages, such as Faradaic reactions, electro-osmotic instabilities, and induced-charge electrokinetic phenomena....

  6. Rethinking Rectification: AC-DC Power Supply in Package

    DEFF Research Database (Denmark)

    Pejtersen, Jens; Knott, Arnold; Jørgensen, Ivan Harald Holger

    Rectification of AC mains voltage is almost exclusively implemented with passive diode bridge rectifiers for power applications below 100 W. The diode bridge rectifier is reliable, cost effective and easy to use. But it is also lossy, nonlinear and passive. Thus reducing the power conversion...

  7. Monolithic blue LED series arrays for high-voltage AC operation

    Energy Technology Data Exchange (ETDEWEB)

    Ao, Jin-Ping [Satellite Venture Business Laboratory, University of Tokushima, Tokushima 770-8506 (Japan); Sato, Hisao; Mizobuchi, Takashi; Morioka, Kenji; Kawano, Shunsuke; Muramoto, Yoshihiko; Sato, Daisuke; Sakai, Shiro [Nitride Semiconductor Co. Ltd., Naruto, Tokushima 771-0360 (Japan); Lee, Young-Bae; Ohno, Yasuo [Department of Electrical and Electronic Engineering, University of Tokushima, Tokushima 770-8506 (Japan)

    2002-12-16

    Design and fabrication of monolithic blue LED series arrays that can be operated under high ac voltage are described. Several LEDs, such as 3, 7, and 20, are connected in series and in parallel to meet ac operation. The chip size of a single device is 150 {mu}m x 120 {mu}m and the total size is 1.1 mm x 1 mm for a 40(20+20) LED array. Deep dry etching was performed as device isolation. Two-layer interconnection and air bridge are utilized to connect the devices in an array. The monolithic series array exhibit the expected operation function under dc and ac bias. The output power and forward voltage are almost proportional to LED numbers connected in series. On-wafer measurement shows that the output power is 40 mW for 40(20+20) LED array under ac 72 V. (Abstract Copyright [2002], Wiley Periodicals, Inc.)

  8. Performance of Three-Arm Ac Automatic Voltage Regulator

    Directory of Open Access Journals (Sweden)

    T. Papinaidu

    2014-04-01

    Full Text Available In this paper the design and simulation of automatic voltage regulator (AVR is proposed. The AVR provides voltage buck and boost capability to eliminate power problems created by under voltage or over voltage fluctuations. It also protects against minor and severe spikes and surges that comprise over 80% of power problems. Over heating of components due to voltage swell is also avoided by using AVR. The switching losses are also reduced as only one arm among three arms is maintained at higher power frequencies depending on mode of operation. Moreover, there is no need to use large capacitor as a result the overall size of converter is also reduced. Hence, the output voltage of the AVR can be maintained at the specified voltage. Hence, the AVR is cost can be reduced, and the efficiency of the power convertor can be extended.

  9. Ac Synchronous Servo Based On The Armature Voltage Prediction Model

    Science.gov (United States)

    Hoshino, Akihiro; Kuromaru, Hiroshi; Kobayashi, Shinichi

    1987-10-01

    A new control method of the AC synchro-nous servo-system (Brushless DC servo-system) is discussed. The new system is based on the armature voltage prediction model. Without a resolver-digital-conver-ter nor a tachometer-generator, the resolver provides following three signals to the system immediately, they are the current command, the induced voltage, and the rotor speed. The new method realizes a simple hardware configuration. Experimental results show a good performance of the system.

  10. Low Voltage Power Supply Incorporating Ceramic Transformer

    CERN Document Server

    Imori, M

    2007-01-01

    A low voltage power supply provides the regulated output voltage of 1 V from the supply voltage around 48 V. The low voltage power supply incorporates a ceramic transformer which utilizes piezoelectric effect to convert voltage. The ceramic transformer isolates the secondary from the primary, thus providing the ground isolation between the supply and the output voltages. The ceramic transformer takes the place of the conventional magnetic transformer. The ceramic transformer is constructed from a ceramic bar and does not include any magnetic material. So the low voltage power supply can operate under a magnetic field. The output voltage is stabilized by feedback. A feedback loop consists of an error amplifier, a voltage controlled oscillator and a driver circuit. The amplitude ratio of the transformer has dependence on the frequency, which is utilized to stabilize the output voltage. The low voltage power supply is investigated on the analogy of the high voltage power supply similarly incorporating the cerami...

  11. A Series-LC-Filtered Active Damper for AC Power Electronics Based Power Systems

    DEFF Research Database (Denmark)

    Wang, Xiongfei; Blaabjerg, Frede; Loh, Poh Chiang

    2015-01-01

    This paper proposes an active damper with a series LC-filter for suppressing resonances in an ac power electronics based power system. The added filter capacitor helps to lower the voltage stress of the converter to be used for implementing the damper. Unlike active filters for the compensation...... is built, where the damper is integrated into a grid-connected converter. The results obtained from the experiments demonstrate the stability enhancement of ac power electronics based power systems by the active damper....

  12. Power Capability in Low Voltage DC Distribution Systems

    Directory of Open Access Journals (Sweden)

    C.O. Gecan

    2009-12-01

    Full Text Available Recent developments in power electronics components enable the use of power electronics in Low Voltage (LV networks. This development makes the model of a Low Voltage Direct Current (LVDC distribution system possible. The technical and economical benefits of this technology make possible the alternative hypothesis of using DC instead of AC distribution systems. Some aspects, such as increasing the capability of the existing lines, interconnecting distributed generation units and even supplying in DC some loads are creating additional requirements of using a LVDC distribution system. The paper presents some general considerations regarding cables used in a LVAC distribution system and different line reconfigurations witch enable the use of cobles in a LVDC distribution system. The reconfigurations are presented in respect of the DC network topologies: unipolar and bipolar. The central aim of this paper is to investigate capability of power transmission and to calculate the transmission distance for cables used in Low Voltage AC and DC distribution systems. Capability computation is considered in respect of two constrains imposed in the cables cross section selection: cable thermal limit and the maximum allowable voltage drop. Cable thermal limit is represented in calculations by the maximum rated current. The equations used to calculate the power capability are presented for single-phase and threephase AC networks and unipolar and bipolar DC networks. Based on these equations, comparisons between power capability of cables with different cross sections used in Low Voltage DC and AC distribution systems are realized and presented.

  13. AC Versus DC Link Comparison Based on Power Flow Analysis of a Multimachine Power System

    OpenAIRE

    Mohammed Abdeljalil DJEHAF; Sid Ahmed ZIDI; Youcef DJILANI KOBIBI

    2014-01-01

    Deregulation and privatization is posing new challenges on high voltage transmission and on distributions systems as well. An increasingly liberalized market will encourage trading opportunities to be identified and developed. High voltage power electronics, such as HVDC (High Voltage Direct Current) and FACTS (Flexible AC Transmission Systems) provide the necessary features to avoid technical problems in heavily loaded power systems; HVDC offers most advantages: it can be used for system int...

  14. Programmable high voltage power supply with regulation confined to the high voltage section

    Science.gov (United States)

    Castell, Karen D. (Inventor); Ruitberg, Arthur P. (Inventor)

    1994-01-01

    A high voltage power supply in a dc-dc converter configuration includes a pre-regulator which filters and regulates the dc input and drives an oscillator which applies, in turn, a low voltage ac signal to the low side of a step-up high voltage transformer. The high voltage side of the transformer drives a voltage multiplier which provides a stepped up dc voltage to an output filter. The output voltage is sensed by a feedback network which then controls a regulator. Both the input and output of the regulator are on the high voltage side, avoiding isolation problems. The regulator furnishes a portion of the drive to the voltage multiplier, avoiding having a regulator in series with the load with its attendant, relatively high power losses. This power supply is highly regulated, has low power consumption, a low parts count and may be manufactured at low cost. The power supply has a programmability feature that allows for the selection of a large range of output voltages.

  15. Voltage source inverters for high power, variable-voltage DC power sources

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Z. [Department of Engineering and Technology, De Montfort University, Queens Building, The Gateway, Leicester, LE1 9BH, (United Kingdom); Spooner, E. [School of Engineering, University of Durham, Science Laboratories, South Rd, Durham, DRI 3LE, (United Kingdom)

    2001-09-01

    The paper discusses the applications of voltage source inverter (VSI) based power electronic systems for interfacing variable-voltage DC sources to the grid. A variable-speed wind power conversion system is used for illustration, where the VSI-based interface needs to convert a variable DC voltage to a nearly constant AC voltage with high-quality power. The power control principles of VSI are described. Various system configurations and switching strategies are examined by analysis, simulation and experimental methods. It is shown that better utilisation of semiconductors and more flexible control may be achieved by using a separately controlled DC link, rather than a directly connected VSI that has to operate at a lower modulation ratio at higher power. In some cases, multipulse inverter structures may be preferred, despite higher component count, because of reduced switching losses, fault tolerance and the absence of filters. The solutions developed in the study could be applied at a different scale to other renewable energy sources, such as wave or solar photovoltaic devices. (Author)

  16. Determination of appropriate DC voltage for switched mode power supply (SMPS) loads

    Science.gov (United States)

    Setiawan, Eko Adhi; Setiawan, Aiman; Purnomo, Andri; Djamal, Muchlishah Hadi

    2017-03-01

    Nowadays, most of modern and efficient household electronic devices operated based on Switched Mode Power Supply (SMPS) technology which convert AC voltage from the grid to DC voltage. Based on theory and experiment, SMPS loads could be supplied by DC voltage. However, the DC voltage rating to energize electronic home appliances is not standardized yet. This paper proposed certain method to determine appropriate DC voltage, and investigated comparison of SMPS power consumption which is supplied from AC and DC voltage. To determine the appropriate DC voltage, lux value of several lamps which have same specification energized by using AC voltage and the results is using as reference. Then, the lamps were supplied by various DC voltage to obtain the trends of the lux value to the applied DC voltage. After that, by using the trends and the reference lux value, the appropriate DC voltage can be determined. Furthermore, the power consumption on home appliances such as mobile phone, laptop and personal computer by using AC voltage and the appropriate DC voltage were conducted. The results show that the total power consumption of AC system is higher than DC system. The total power (apparent power) consumed by the lamp, mobile phone and personal computer which operated in 220 VAC were 6.93 VA, 34.31 VA and 105.85 VA respectively. On the other hand, under 277 VDC the load consumption were 5.83 W, 19.11 W and 74.46 W respectively.

  17. Power conditioning for low-voltage piezoelectric stack energy harvesters

    Science.gov (United States)

    Skow, E.; Leadenham, S.; Cunefare, K. A.; Erturk, A.

    2016-04-01

    Low-power vibration and acoustic energy harvesting scenarios typically require a storage component to be charged to enable wireless sensor networks, which necessitates power conditioning of the AC output. Piezoelectric beam-type bending mode energy harvesters or other devices that operate using a piezoelectric element at resonance produce high voltage levels, for which AC-DC converters and step-down DC-DC converters have been previously investigated. However, for piezoelectric stack energy harvesters operating off-resonance and producing low voltage outputs, a step-up circuit is required for power conditioning, such as seen in electromagnetic vibration energy scavengers, RF communications, and MEMS harvesters. This paper theoretically and experimentally investigates power conditioning of a low-voltage piezoelectric stack energy harvester.

  18. POWER FACTOR IMPROVEMENT IN THREE PHASE AC-AC CONVERTER THROUGH MODIFIED SPWM

    Directory of Open Access Journals (Sweden)

    P.VASUKI,

    2011-02-01

    Full Text Available Recently, a new generation of ac-ac single-phase and three-phase power converters with more commutations per half cycle has been proposed for ac power due to the increasing availability and power capability of high frequency controlled-on and off power emiconductor switching devices. This paper presents three phase ac-acconverter whose control strategy is based on modified sinusoidal ulse-width modulation switching technique. As majority of the industrial loads are being inductive, the power factor is less. To improve the power factor, the delayed current is shifted to the input voltage, through a modification of the classical sinusoidal pulse width modulation switching technique. In this way, the decrease in the phase angle between the input current and voltage is feasible, and consequently, high cost compensation capacitors can be avoided. The improvement of power factor through this switching technique on the proposed converter is investigated and verified via simulation using the software Matlab/Simulink.

  19. Strongly nonlinear dynamics of electrolytes in large ac voltages

    CERN Document Server

    Olesen, Laurits H; Bruus, Henrik

    2009-01-01

    We study the response of a model micro-electrochemical cell to a large ac voltage of frequency comparable to the inverse cell relaxation time. To bring out the basic physics, we consider the simplest possible model of a symmetric binary electrolyte confined between parallel-plate blocking electrodes, ignoring any transverse instability or fluid flow. We analyze the resulting one-dimensional problem by matched asymptotic expansions in the limit of thin double layers and extend previous work into the strongly nonlinear regime, which is characterized by two novel features - significant salt depletion in the electrolyte near the electrodes and, at very large voltage, the breakdown of the quasi-equilibrium structure of the double layers. The former leads to the prediction of "ac capacitive desalination", since there is a time-averaged transfer of salt from the bulk to the double layers, via oscillating diffusion layers. The latter is associated with transient diffusion limitation, which drives the formation and co...

  20. Safe-commutation principle for direct single-phase AC-AC converters for use in audio power amplification

    DEFF Research Database (Denmark)

    Ljusev, Petar; Andersen, Michael Andreas E.

    2004-01-01

    This paper presents an alternative safe commutation principle for a single phase bidirectional bridge, for use in the new generation of direct single-stage AC-AC audio power amplifiers. As compared with the bridge commutation with load current or source voltage sensing, in this approach...

  1. Safe-commutation principle for direct single-phase AC-AC converters for use in audio power amplification

    DEFF Research Database (Denmark)

    Ljusev, Petar; Andersen, Michael Andreas E.

    2004-01-01

    This paper presents an alternative safe commutation principle for a single phase bidirectional bridge, for use in the new generation of direct single-stage AC-AC audio power amplifiers. As compared with the bridge commutation with load current or source voltage sensing, in this approach...

  2. A Non-linear Controller for Single-Phase AC-AC Power Converter to meet UPS Performance Index

    Directory of Open Access Journals (Sweden)

    Abdelhafid Ait Elmahjoub

    2012-07-01

    Full Text Available This article focuses on AC-AC power converter that can be used for uninterruptible power supply (UPS. The converter is built on two stages: a AC-DC input stage and a DC-AC output stage. The two blocks are connected by an intermediate DC bus. The aim of control is threefold: i power factor correction ii regulation of DC bus iii generating a sinusoidal voltage at the output. The synthesis of controllers has been achieved through the technique of nonlinear backstepping control. A detailed analysis of the stability control system is presented. The performances of regulators have been validated by numerical simulation in MATLAB / SIMULINK.

  3. A Review on Power System Voltage Stability and Optimization Techniques

    Directory of Open Access Journals (Sweden)

    T. Madhuranthaka

    2016-11-01

    Full Text Available Power system voltage stability is a one of the major focused areas in recent days due to mismatch between generation and demand. Maintenance of voltage stability is a challenging issue in planning and security assessment of power systems. Voltage stability is the ability of a power system to maintain steady acceptable voltages at all buses in the power system under normal operating conditions and after being subjected to a disturbance. Long-term voltage instability problems can occur in heavily loaded systems where the electrical distance is large between the generator and the load. Timely application of reactive power compensation or load shedding may prevent this type of voltage instability. System reactive power handling capacity can be improved with Flexible AC Transmission System (FACTS devices. Identification of critical system locations to undertake appropriate remedial measures in operation is the concern. This paper reviews the performance of various types FACTS controllers in power system voltage stability problem and focuses on different optimization methods implemented for optimal placement and sizing of FACTS devices to minimize power losses.

  4. Enhanced DC-Link Capacitor Voltage Balancing Control of DC–AC Multilevel Multileg Converters

    DEFF Research Database (Denmark)

    Busquets-Monge, Sergio; Maheshwari, Ram Krishan; Nicolas-Apruzzese, Joan

    2015-01-01

    This paper presents a capacitor voltage balancing control applicable to any multilevel dc–ac converter formed by a single set of series-connected capacitors implementing the dc link and semiconductor devices, such as the diode-clamped topology. The control is defined for any number of dc......-link voltage levels and converter legs (for single-phase and multiphase systems), guaranteeing the capacitor voltage control for any modulation index value and load (from idle mode to full power). The associated control loop small-signal transfer function is presented, from which optimum compensator design...... guidelines are derived. The improvement in control performance is verified through simulation and experiments comparing with a previous balancing control strategy in a four-level three-phase dc–ac conversion system. The satisfactory control performance is also verified through simulation in a four-level five...

  5. Three-phase AC-AC power converters based on matrix converter topology matrix-reactance frequency converters concept

    CERN Document Server

    Szczesniak, Pawel

    2013-01-01

    AC voltage frequency changes is one of the most important functions of solid state power converters. The most desirable features in frequency converters are the ability to generate load voltages with arbitrary amplitude and frequency, sinusoidal currents and voltages waveforms; the possibility of providing unity power factor for any load; and, finally, a simple and compact power circuit. Over the past decades, a number of different frequency converter topologies have appeared in the literature, but only the converters with either a voltage or current DC link are commonly used in industrial app

  6. Application of Distribution Power Electronic Transformer for Medium Voltage

    Directory of Open Access Journals (Sweden)

    Prashant Kumar

    2014-12-01

    Full Text Available In   this   paper   a   distribution   power electronic transformer (DPET for feeding critical loads is presented. The PE based transformer is a multi-port converter that can connect to medium voltage levels on the primary side. Bidirectional power flow is provided to the each module. The presented structure consists of three stages: an input stage, an isolation stage, and an output stage.  The input current is sinusoidal, and it converts the high AC input voltage to low DC voltages. The isolated DC/DC converters are then connected to the DC links and provide galvanic isolation between the HV and LV sides. Finally, a three-phase inverter generates the AC output with the desired amplitude and frequency. The proposed DPET is extremely modular and can be extended for different voltage and power levels. It performs typical functions and has advantages such as power factor correction, elimination of voltage sag and swell, and reduction of voltage flicker in load side. Also in comparison to conventional transformers, it has lower weight, lower volume and eliminates necessity for toxic dielectric coolants the DPET performance is verified in MATLAB simulation.

  7. A Switched Capacitor Based AC/DC Resonant Converter for High Frequency AC Power Generation

    Directory of Open Access Journals (Sweden)

    Cuidong Xu

    2015-09-01

    Full Text Available A switched capacitor based AC-DC resonant power converter is proposed for high frequency power generation output conversion. This converter is suitable for small scale, high frequency wind power generation. It has a high conversion ratio to provide a step down from high voltage to low voltage for easy use. The voltage conversion ratio of conventional switched capacitor power converters is fixed to n, 1/n or −1/n (n is the switched capacitor cell. In this paper, A circuit which can provide n, 1/n and 2n/m of the voltage conversion ratio is presented (n is stepping up the switched capacitor cell, m is stepping down the switching capacitor cell. The conversion ratio can be changed greatly by using only two switches. A resonant tank is used to assist in zero current switching, and hence the current spike, which usually exists in a classical switching switched capacitor converter, can be eliminated. Both easy operation and efficiency are possible. Principles of operation, computer simulations and experimental results of the proposed circuit are presented. General analysis and design methods are given. The experimental result verifies the theoretical analysis of high frequency AC power generation.

  8. Low-Cost Voltage Zero-Crossing Detector for AC-Grid Applications

    Directory of Open Access Journals (Sweden)

    Vorobyov Maxim

    2014-10-01

    Full Text Available Renewable energy sources and energy storage devices are becoming more popular. Some of them like small hydropower turbines, wind turbines and diesel generators produce AC voltage with different frequency and voltage than the main grid. For them power electronics converters are necessary. Power electronics converters presented in industry use two or three level energy conversion, although direct AC to AC converters exist, but one of the main problems is the switch commutation when current or voltage is crossing the zero point. Zero crossing sensors are used to solve this problem. They consist of current or voltage measurement unit and zero crossing detector. Different approaches are used for zero crossing: hardware or software. Hardware approach is simple but it has low precision. Software approach has high precision but it is complicated and expensive. In this paper a simple low cost high precision approach is presented. It takes all advantages from both approaches. While tested with two types of microcontrollers the precision of experimental measurement is 25 μs - 40 μs.

  9. Power Electronic Transformer based Three-Phase PWM AC Drives

    Science.gov (United States)

    Basu, Kaushik

    A Transformer is used to provide galvanic isolation and to connect systems at different voltage levels. It is one of the largest and most expensive component in most of the high voltage and high power systems. Its size is inversely proportional to the operating frequency. The central idea behind a power electronic transformer (PET) also known as solid state transformer is to reduce the size of the transformer by increasing the frequency. Power electronic converters are used to change the frequency of operation. Steady reduction in the cost of the semiconductor switches and the advent of advanced magnetic materials with very low loss density and high saturation flux density implies economic viability and feasibility of a design with high power density. Application of PET is in generation of power from renewable energy sources, especially wind and solar. Other important application include grid tied inverters, UPS e.t.c. In this thesis non-resonant, single stage, bi-directional PET is considered. The main objective of this converter is to generate adjustable speed and magnitude pulse width modulated (PWM) ac waveforms from an ac or dc grid with a high frequency ac link. The windings of a high frequency transformer contains leakage inductance. Any switching transition of the power electronic converter connecting the inductive load and the transformer requires commutation of leakage energy. Commutation by passive means results in power loss, decrease in the frequency of operation, distortion in the output voltage waveform, reduction in reliability and power density. In this work a source based partially loss-less commutation of leakage energy has been proposed. This technique also results in partial soft-switching. A series of converters with novel PWM strategies have been proposed to minimize the frequency of leakage inductance commutation. These PETs achieve most of the important features of modern PWM ac drives including 1) Input power factor correction, 2) Common

  10. Prediction of Pollution Flashover Voltage Based on Leakage Current Under AC Operating Voltage

    Institute of Scientific and Technical Information of China (English)

    MEI Hongwei; WANG Liming; GUAN Zhicheng; MAO Yingke

    2012-01-01

    This paper presented a model to predict the AC flashover voltage of contaminated suspension insulators.The prediction method is based on the maximum leakage current under AC operating voltage.Three kinds of widely used suspension insulators were tested in various contamination states such as pollution layers with different equivalent salt deposit density(ESDD),different composition of the conductive components,different non-soluble deposit density(NSDD) and different pollution distribution states to simulate the contamination states in nature.The effective ESDD was proposed and calculated.Influences of contamination states to maximum leakage current and flashover voltage were studied.Then,the relationships between flashover voltage and leakage current in these states were presented.Finally,considering the difference of insulator profiles,a new parameter is defined and a model to estimate the flashover voltage based on this parameter is developed.The model could be used in all kinds of suspension insulators in different contamination states and was validated by the test results.

  11. Intertied ac–ac microgrids with autonomous power import and export

    DEFF Research Database (Denmark)

    Nutkani, Inam Ullah; Loh, Poh Chiang; Wang, Peng

    2015-01-01

    Intertied ac–ac microgrids offer many potential benefits like flexible frequency and voltage selection, reserve sharing and enhanced supply reliability. Operating them is however challenging due to their larger size and presence of more power converters with different responsibilities. These comp......Intertied ac–ac microgrids offer many potential benefits like flexible frequency and voltage selection, reserve sharing and enhanced supply reliability. Operating them is however challenging due to their larger size and presence of more power converters with different responsibilities...

  12. Control of Power Converters in AC Microgrids

    DEFF Research Database (Denmark)

    Rocabert, Joan; Luna, Alvaro; Blaabjerg, Frede

    2012-01-01

    The enabling of ac microgrids in distribution networks allows delivering distributed power and providing grid support services during regular operation of the grid, as well as powering isolated islands in case of faults and contingencies, thus increasing the performance and reliability of the ele......The enabling of ac microgrids in distribution networks allows delivering distributed power and providing grid support services during regular operation of the grid, as well as powering isolated islands in case of faults and contingencies, thus increasing the performance and reliability...

  13. Common-mode Voltage Reduction in a Motor Drive System with a Power Factor Correction

    DEFF Research Database (Denmark)

    Adabi, J.; Boora, A.A.; Zare, F.;

    2012-01-01

    to reduce shaft voltage in a three-phase AC motor drive system. In this topology, the AC-DC diode rectifier influences the common-mode voltage generated by the inverter because the placement of the neutral point is changing in different rectifier circuit states. A pulse width modulation technique......Common-mode voltage generated by a power converter in combination with parasitic capacitive couplings is a potential source of shaft voltage in an AC motor drive system. In this study, a three-phase motor drive system supplied with a single-phase AC-DC diode rectifier is investigated in order...... is presented by a proper placement of the zero vectors to reduce the common-mode voltage level, which leads to a cost-effective shaft voltage reduction technique without load current distortion, while keeping the switching frequency constant. Analysis, simulations and experimental implementation have been...

  14. Local Dynamic Reactive Power for Correction of System Voltage Problems

    Energy Technology Data Exchange (ETDEWEB)

    Kueck, John D [ORNL; Rizy, D Tom [ORNL; Li, Fangxing [ORNL; Xu, Yan [ORNL; Li, Huijuan [University of Tennessee, Knoxville (UTK); Adhikari, Sarina [ORNL; Irminger, Philip [ORNL

    2008-12-01

    Distribution systems are experiencing outages due to a phenomenon known as local voltage collapse. Local voltage collapse is occurring in part because modern air conditioner compressor motors are much more susceptible to stalling during a voltage dip than older motors. These motors can stall in less than 3 cycles (.05s) when a fault, such as on the sub-transmission system, causes voltage to sag to 70 to 60%. The reasons for this susceptibility are discussed in the report. During the local voltage collapse, voltages are depressed for a period of perhaps one or two minutes. There is a concern that these local events are interacting together over larger areas and may present a challenge to system reliability. An effective method of preventing local voltage collapse is the use of voltage regulation from Distributed Energy Resources (DER) that can supply or absorb reactive power. DER, when properly controlled, can provide a rapid correction to voltage dips and prevent motor stall. This report discusses the phenomenon and causes of local voltage collapse as well as the control methodology we have developed to counter voltage sag. The problem is growing because of the use of low inertia, high efficiency air conditioner (A/C) compressor motors and because the use of electric A/C is growing in use and becoming a larger percentage of system load. A method for local dynamic voltage regulation is discussed which uses reactive power injection or absorption from local DER. This method is independent, rapid, and will not interfere with conventional utility system voltage control. The results of simulations of this method are provided. The method has also been tested at the ORNL s Distributed Energy Communications and Control (DECC) Laboratory using our research inverter and synchronous condenser. These systems at the DECC Lab are interconnected to an actual distribution system, the ORNL distribution system, which is fed from TVA s 161kV sub-transmission backbone. The test results

  15. 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.

  16. Distributed AC power flow method for AC and AC-DC hybrid ...

    African Journals Online (AJOL)

    DR OKE

    Present MGs incorporate AC and DC sources and loads along with storage and power ... Keywords: Microgrid (MG), Distributed Energy Resources (DER), Particle ... But in case of renewable based MGs, where small and intermittent sources ...

  17. A fiber optic hybrid multifunctional AC voltage sensor

    Energy Technology Data Exchange (ETDEWEB)

    Sokolovsky, A.; Zadvornov, S. [IRE, Moscow (Russian Federation); Ryabko, M. [UFD, Moscow (Russian Federation)

    2008-07-01

    Hybrid sensors have the advantages of both electronic and optical technologies. Their sensing element is based on conventional transducers and the optical fiber is used as a transmission media for the optical signal encoded with information between the local module and the remote module. The power supply for the remote module is usually provided by a built-in photoelectric converter illuminated by the optical radiation going through the same or another optical fiber. Electro-optic hybrid sensors have been widely used because of the electrical isolation provided by optical fiber. In the conventional fiber optic voltage sensor, piezoelectric or electro-optic transducers are implemented. Processing and conditioning measurement information is a complex task in these sensors. Moreover, the considerable drawback of most of these systems is that only one parameter, usually voltage value, is measured. This paper presented a novel fiber optic hybrid sensor for alternating current voltage measurements. This instrument provides the simultaneous measurement of four parameters, notably voltage value, frequency, phase angle and the external temperature. The paper described the measurement technology of the instrument including the remote module and optical powering as well as the unique modulation algorithm. The results and conclusions were also presented. 7 refs., 4 figs.

  18. Power-supply-operations group-training programs, ac/dc power systems and micellaneous information

    Energy Technology Data Exchange (ETDEWEB)

    Harris, C A

    1978-06-30

    This program introduces the technician to three phase a-c power and its relationship to rectifier power conversion systems. A brief introduction is given as to the engineering significance of various parameters such as, phase rotation, ac power relationships, harmonics, transformer voltage vectors, rectifier parameters, filters, water cooling, phase delayed triggers to SCR's, dielectric stress vs life and other related subjects. The significance of the details as they apply to various diagnostic problems that a technician may be called upon to solve is emphasized. Reference CAPE-2747.

  19. 21 CFR 886.1850 - AC-powered slitlamp biomicroscope.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false AC-powered slitlamp biomicroscope. 886.1850... (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1850 AC-powered slitlamp biomicroscope. (a) Identification. An AC-powered slitlamp biomicroscope is an AC-powered device that is...

  20. 21 CFR 886.4440 - AC-powered magnet.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false AC-powered magnet. 886.4440 Section 886.4440 Food... DEVICES OPHTHALMIC DEVICES Surgical Devices § 886.4440 AC-powered magnet. (a) Identification. An AC-powered magnet is an AC-powered device that generates a magnetic field intended to find and...

  1. 21 CFR 888.1240 - AC-powered dynamometer.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false AC-powered dynamometer. 888.1240 Section 888.1240...) MEDICAL DEVICES ORTHOPEDIC DEVICES Diagnostic Devices § 888.1240 AC-powered dynamometer. (a) Identification. An AC-powered dynamometer is an AC-powered device intended for medical purposes to...

  2. 21 CFR 886.1630 - AC-powered photostimulator.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false AC-powered photostimulator. 886.1630 Section 886...) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1630 AC-powered photostimulator. (a) Identification. An AC-powered photostimulator is an AC-powered device intended to provide light stimulus...

  3. Surge currents and voltages at the low voltage power mains during lightning strike to a GSM tower

    Energy Technology Data Exchange (ETDEWEB)

    Markowska, Renata [Bialystok Technical University (Poland)], E-mail: remark@pb.edu.pl

    2007-07-01

    The paper presents the results of numerical calculations of lightning surge currents and voltages in the low voltage power mains system connected to a free standing GSM base station. Direct lightning strike to GSM tower was studied. The analysis concerned the current that flows to the transformer station through AC power mains, the potential difference between the grounding systems of the GSM and the transformer stations and the voltage differences between phase and PE conductors of the power mains underground cable at both the GSM and the transformer sides. The calculations were performed using a numerical program based on the electromagnetic field theory and the method of moments. (author)

  4. A Communication-Less Distributed Voltage Control Strategy for a Multi-Bus AC Islanded Microgrid

    DEFF Research Database (Denmark)

    Wang, Yanbo; Tan, Yongdong; Chen, Zhe

    2014-01-01

    This paper presents a communication-less distributed voltage control strategy for a multi-bus AC islanded microgrid. First, a Kalman Filter-based network voltage estimator is proposed to obtain voltage responses without communication links in the presence of load disturbances. Then, a voltage opt...

  5. 49 CFR 236.551 - Power supply voltage; requirement.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Power supply voltage; requirement. 236.551 Section... supply voltage; requirement. The voltage of power supply shall be maintained within 10 percent of rated voltage....

  6. Power flow control and voltage stability limit: regulating transformer versus UPFC

    Energy Technology Data Exchange (ETDEWEB)

    Haque, M.H. [Nanyang Technological Univ., Center for Advanced Power Electronics, Nanyang (Singapore)

    2004-05-01

    Power flow through an AC transmission line can be controlled by injecting an adjustable compensating voltage in series with the line. This paper evaluates and compares the power flow control ranges of a simple system obtained by injecting an adjustable series compensating voltage produced by a regulating transformer and unified power flow controller. The static voltage stability limits of the system with a regulating transformer and unified power flow controller are also determined and compared. In evaluating the power flow control ranges and voltage stability limits, the transmission line of the system is modelled in four different ways. The results obtained for various line models are also compared. (Author)

  7. High Efficiency Power Converter for Low Voltage High Power Applications

    DEFF Research Database (Denmark)

    Nymand, Morten

    , and remote power generation for light towers, camper vans, boats, beacons, and buoys etc. A review of current state-of-the-art is presented. The best performing converters achieve moderately high peak efficiencies at high input voltage and medium power level. However, system dimensioning and cost are often......The topic of this thesis is the design of high efficiency power electronic dc-to-dc converters for high-power, low-input-voltage to high-output-voltage applications. These converters are increasingly required for emerging sustainable energy systems such as fuel cell, battery or photo voltaic based...... determined by the performance at the system worst case operating point which is usually at minimum input voltage and maximum power. Except for the non-regulating V6 converters, all published solutions exhibit a very significant drop in conversion efficiency at minimum input voltage and maximum output power...

  8. Wind Power Plant Voltage Stability Evaluation: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Muljadi, E.; Zhang, Y. C.

    2014-09-01

    Voltage stability refers to the ability of a power system to maintain steady voltages at all buses in the system after being subjected to a disturbance from a given initial operating condition. Voltage stability depends on a power system's ability to maintain and/or restore equilibrium between load demand and supply. Instability that may result occurs in the form of a progressive fall or rise of voltages of some buses. Possible outcomes of voltage instability are the loss of load in an area or tripped transmission lines and other elements by their protective systems, which may lead to cascading outages. The loss of synchronism of some generators may result from these outages or from operating conditions that violate a synchronous generator's field current limit, or in the case of variable speed wind turbine generator, the current limits of power switches. This paper investigates the impact of wind power plants on power system voltage stability by using synchrophasor measurements.

  9. Cryocooler operation of SNIS Josephson arrays for AC Voltage standards

    Science.gov (United States)

    Sosso, A.; De Leo, N.; Fretto, M.; Monticone, E.; Roncaglione, L.; Rocci, R.; Lacquaniti, V.

    2014-05-01

    Avoiding liquid helium is now a worldwide issue, thus cryocooler operation is becoming mandatory for a wider use of superconductive electronics. Josephson voltage standards hold a peculiar position among superconducting devices, as they are in use in high precision voltage metrology since decades. Higher temperature operation would reduce the refrigerator size and complexity, however, arrays of Josephson junctions made with high temperature superconductors for voltage standard applications are not to date available. The SNIS (Superconductor-Normal metal-Insulator-Superconductor) junction technology developed at INRIM, based on low temperature superconductors, but capable of operation well above liquid helium temperature, is interesting for application to a compact cryocooled standard, allowing to set a compromise between device and refrigerator requirements. In this work, the behavior of SNIS devices cooled with a closed-cycle refrigerator has been investigated, both in DC and under RF irradiation. Issues related to thermal design of the apparatus to solve specific problems not faced with liquid coolants, like reduced cooling power and minimization of thermal gradients for uniform operation of the chip are discussed in detail.

  10. Transmission Technologies and Operational Characteristic Analysis of Hybrid UHV AC/DC Power Grids in China

    Science.gov (United States)

    Tian, Zhang; Yanfeng, Gong

    2017-05-01

    In order to solve the contradiction between demand and distribution range of primary energy resource, Ultra High Voltage (UHV) power grids should be developed rapidly to meet development of energy bases and accessing of large-scale renewable energy. This paper reviewed the latest research processes of AC/DC transmission technologies, summarized the characteristics of AC/DC power grids, concluded that China’s power grids certainly enter a new period of large -scale hybrid UHV AC/DC power grids and characteristics of “strong DC and weak AC” becomes increasingly pro minent; possible problems in operation of AC/DC power grids was discussed, and interaction or effect between AC/DC power grids was made an intensive study of; according to above problems in operation of power grids, preliminary scheme is summarized as fo llows: strengthening backbone structures, enhancing AC/DC transmission technologies, promoting protection measures of clean energ y accessing grids, and taking actions to solve stability problems of voltage and frequency etc. It’s valuable for making hybrid UHV AC/DC power grids adapt to operating mode of large power grids, thus guaranteeing security and stability of power system.

  11. AC Versus DC Link Comparison Based on Power Flow Analysis of a Multimachine Power System

    Directory of Open Access Journals (Sweden)

    Mohammed Abdeljalil DJEHAF

    2014-02-01

    Full Text Available Deregulation and privatization is posing new challenges on high voltage transmission and on distributions systems as well. An increasingly liberalized market will encourage trading opportunities to be identified and developed. High voltage power electronics, such as HVDC (High Voltage Direct Current and FACTS (Flexible AC Transmission Systems provide the necessary features to avoid technical problems in heavily loaded power systems; HVDC offers most advantages: it can be used for system interconnection and for control of power flow as well. The major benefit of HVDC is its incorporated ability for fault-current blocking, which is not possible with synchronous AC links. In addition, HVDC can effectively support the surrounding AC systems in case of transient fault conditions and it serves as firewall against cascading disturbances. This paper presents a comparison between HVDC link and an HVAC link in a 29 Bus multimachine system, based on load flow analysis using Newton-Raphson method for the AC link case, and sequential method for the HVDC link case.

  12. Regular structures in 5CB liquid crystals under the joint action of ac and dc voltages

    Science.gov (United States)

    Aguirre, Luis E.; Anoardo, Esteban; Éber, Nándor; Buka, Ágnes

    2012-04-01

    A nematic liquid crystal with high, positive dielectric anisotropy (5CB) has been studied under the influence of the combined action of a dc and an ac electric field. Broad frequency, voltage, and cell thickness ranges were considered. Pattern morphologies were identified; the thresholds and critical wave numbers were measured and analyzed as a function of frequency, dc-to-ac voltage ratio, and thickness. The current-voltage characteristics were simultaneously detected.

  13. Voltage scheduling for low power/energy

    Science.gov (United States)

    Manzak, Ali

    2001-07-01

    Power considerations have become an increasingly dominant factor in the design of both portable and desk-top systems. An effective way to reduce power consumption is to lower the supply voltage since voltage is quadratically related to power. This dissertation considers the problem of lowering the supply voltage at (i) the system level and at (ii) the behavioral level. At the system level, the voltage of the variable voltage processor is dynamically changed with the work load. Processors with limited sized buffers as well as those with very large buffers are considered. Given the task arrival times, deadline times, execution times, periods and switching activities, task scheduling algorithms that minimize energy or peak power are developed for the processors equipped with very large buffers. A relation between the operating voltages of the tasks for minimum energy/power is determined using the Lagrange multiplier method, and an iterative algorithm that utilizes this relation is developed. Experimental results show that the voltage assignment obtained by the proposed algorithm is very close (0.1% error) to that of the optimal energy assignment and the optimal peak power (1% error) assignment. Next, on-line and off-fine minimum energy task scheduling algorithms are developed for processors with limited sized buffers. These algorithms have polynomial time complexity and present optimal (off-line) and close-to-optimal (on-line) solutions. A procedure to calculate the minimum buffer size given information about the size of the task (maximum, minimum), execution time (best case, worst case) and deadlines is also presented. At the behavioral level, resources operating at multiple voltages are used to minimize power while maintaining the throughput. Such a scheme has the advantage of allowing modules on the critical paths to be assigned to the highest voltage levels (thus meeting the required timing constraints) while allowing modules on non-critical paths to be assigned

  14. Corona noise model of high-voltage AC transmission lines and engineering applications

    Institute of Scientific and Technical Information of China (English)

    Wu Jiuhui; Di Zelong

    2013-01-01

    In order to predict the levels of corona noise from high-voltage alternating current (AC) transmission lines,the mechanism of corona noise and the corresponding theoretical prediction model are investigated.On the basis of Drude model,the motion of positive and negative ions produced by high-voltage corona is analyzed,and the mechanism of corona noise is discovered.The theoretical prediction model is put forward by using Kirchhoff formula,which is verified by the well agreement between our result and others',considering the case of three-phase single lines.Moreover,the calculation results show that for both single and bundled lines,the sound pressure level of the typical frequency,i.e.twice the power frequency,attenuates slowly and leads to an obviously interferential phenomenon near the transmission lines,but the level of the bundled lines is smaller than that of the single ones under the same transmission voltage.Based on the mechanism of corona noise and the prediction model,it is obvious that bundled lines and/or increased line radius can be adopted to reduce corona noise in the practical engineering applications effectively.This model can also provide a theoretical guidance for the high-volt-age AC transmission line design.

  15. Reliability of emergency ac power systems at nuclear power plants

    Energy Technology Data Exchange (ETDEWEB)

    Battle, R E; Campbell, D J

    1983-07-01

    Reliability of emergency onsite ac power systems at nuclear power plants has been questioned within the Nuclear Regulatory Commission (NRC) because of the number of diesel generator failures reported by nuclear plant licensees and the reactor core damage that could result from diesel failure during an emergency. This report contains the results of a reliability analysis of the onsite ac power system, and it uses the results of a separate analysis of offsite power systems to calculate the expected frequency of station blackout. Included is a design and operating experience review. Eighteen plants representative of typical onsite ac power systems and ten generic designs were selected to be modeled by fault trees. Operating experience data were collected from the NRC files and from nuclear plant licensee responses to a questionnaire sent out for this project.

  16. 1000 kV 交流特高压输电线路运行特性分析%Analysis of 1 000 kV AC Ultra High Voltage Power Transmission Line Operation Characteristics

    Institute of Scientific and Technical Information of China (English)

    曹旭佳

    2015-01-01

    1000 kV 交流特高压输电线路是解决我国电力能源分布不均匀,降低电力负荷的有效手段。1000 kV 交流特高压线路的维护工作也开始受到社会各界的广泛关注。为了保障交流特高压线路能够安全运行,文章分析了1000 kV 交流特高压输电线路运行特性,借鉴了国外先进经验,总结了其中的关键技术。%1 000 kV AC UHV transmission line is an effective means of uneven distribution of electric energy,reduce the power load solutions,the maintenance work of 1 000 kV AC UHV line has begun to attract widespread concern in the community,in order to protect AC UHV safe operation,we must summarize the key technologies,learn from foreign ad-vanced experience,this paper analyzes the operating characteristics of 1 000 kV UHV AC transmission lines.

  17. Dual voltage power supply with 48 volt

    Energy Technology Data Exchange (ETDEWEB)

    Froeschl, Joachim; Proebstle, Hartmut; Sirch, Ottmar [BMW Group, Muenchen (Germany)

    2012-11-01

    Automotive electrics/electronics have just reached a period of tremendous change. High voltage systems for Hybrid, Plug-In Hybrid or Battery Electric Vehicles with high power electric motors, high energy accumulators and electric climate compressors will be introduced in order to achieve the challenging targets for CO{sub 2} emissions and energy efficiency and to anticipate the mobility of the future. Additionally, innovations and the continuous increase of functionality for comfort, safety, driver assistance and infotainment systems require more and more electrical power of the vehicle power supply at all. On the one hand side electrified vehicles will certainly achieve a significant market share, on the other hand side they will increase the pressure to conventional vehicles with combustion engines for fuel consumption and CO{sub 2} emissions. These vehicles will be enabled to keep their competitiveness by new functions and the optimization of their electric systems. A dual voltage power supply with 48 Volt and 12 Volt will be one of the key technologies to realize these requirements. The power capability of the existing 12 Volt power supply has reached its limits. Further potentials can only be admitted by the introduction of 48 Volt. For this reason the car manufacturers Audi, BMW, Daimler, Porsche and Volkswagen started very early on this item and developed a common specification of the new voltage range. Now, it is necessary to identify the probable systems at this voltage range and to start the developments. (orig.)

  18. AC Power Local Network with Multiple Power Routers

    Directory of Open Access Journals (Sweden)

    Ryo Takahashi

    2013-12-01

    Full Text Available Controlling power flow and achieving appropriate matching between power sources and loads according to the quality of energy is expected to be one of the approaches to reduce wasted energy consumption. A power router, proposed recently, has the capability of realizing circuit switching in a power distribution network. This study focuses on the feasibility of an AC power routing network system composed of multiple power routers. To evaluate the feasibility, we experimentally confirm the circuit switching operation of the parallel and series configurations of the power routers, so that the network system can be designed by the combination of parallel and series configurations.

  19. Output stages inside a negative feedback loop: application to a low-voltage three-phase DC-AC converter for educational purposes

    CERN Document Server

    Llopis, Francisco

    2013-01-01

    The circuit presented in this paper aims at providing three 40 Vpp 50Hz AC voltages sources with 120-degree phase separation between them. This is a fully analogue circuit that uses standard, low-cost electronic components without resorting to a microcontroller as previously proposed by Shirvasar et al [1]. This circuit may serve as a basis for a low-voltage 3P-AC power supply that students may safely use to realize experiments, i.e. about the principles and applications of three-phase AC power lines, without the risk of electric shocks.

  20. Control of VSC-HVDC in offshore AC islands with wind power plants: Comparison of two alternatives

    DEFF Research Database (Denmark)

    Zeni, Lorenzo; Hesselbæk, Bo; Sørensen, Poul Ejnar;

    2015-01-01

    The subject of this paper is the control of offshore AC collection and export networks behind a voltage source converter based high voltage direct current transmission system. The inertia-less nature of such grids makes the control of voltages and power flows potentially more flexible, but at the...

  1. 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.

  2. High-power converters and AC drives

    CERN Document Server

    Wu, Bin

    2017-01-01

    This new edition reflects the recent technological advancements in the MV drive industry, such as advanced multilevel converters and drive configurations. It includes three new chapters, Control of Synchronous Motor Drives, Transformerless MV Drives, and Matrix Converter Fed Drives. In addition, there are extensively revised chapters on Multilevel Voltage Source Inverters and Voltage Source Inverter-Fed Drives. This book includes a systematic analysis on a variety of high-power multilevel converters, illustrates important concepts with simulations and experiments, introduces various megawatt drives produced by world leading drive manufacturers, and addresses practical problems and their mitigations methods.

  3. Mitigation of voltage sag, swell and power factor correction using solid-state transformer b

    Directory of Open Access Journals (Sweden)

    M.R. Banaei

    2014-09-01

    Full Text Available This paper presents a novel topology of solid-state transformer (SST. In the design process, the AC/DC, DC/AC and AC/AC converters have been integrated to achieve higher efficiency. To obtain higher efficiency from other SST with DC-link topologies, the AC/DC and DC/AC converters have been integrated in one matrix converter. The proposed SST performs typical functions and has advantages such as power factor correction, voltage sag and swell elimination, voltage flicker reduction and protection capability in fault situations. In addition, it has other benefits such as light weight, low volume and elimination of hazardous liquid dielectrics because it uses medium frequency transformer. The operation and some performances of the proposed SST have been verified by the simulation results.

  4. Index-based reactive power compensation scheme for voltage regulation

    Science.gov (United States)

    Dike, Damian Obioma

    2008-10-01

    Increasing demand for electrical power arising from deregulation and the restrictions posed to the construction of new transmission lines by environment, socioeconomic, and political issues had led to higher grid loading. Consequently, voltage instability has become a major concern, and reactive power support is vital to enhance transmission grid performance. Improved reactive power support to distressed grid is possible through the application of relatively unfamiliar emerging technologies of "Flexible AC Transmission Systems (FACTS)" devices and "Distributed Energy Resources (DERS)." In addition to these infrastructure issues, a lack of situational awareness by system operators can cause major power outages as evidenced by the August 14, 2003 widespread North American blackout. This and many other recent major outages have highlighted the inadequacies of existing power system indexes. In this work, a novel "Index-based reactive compensation scheme" appropriate for both on-line and off-line computation of grid status has been developed. A new voltage stability index (Ls-index) suitable for long transmission lines was developed, simulated, and compared to the existing two-machine modeled L-index. This showed the effect of long distance power wheeling amongst regional transmission organizations. The dissertation further provided models for index modulated voltage source converters (VSC) and index-based load flow analysis of both FACTS and microgrid interconnected power systems using the Newton-Raphson's load flow model incorporated with multi-FACTS devices. The developed package has been made user-friendly through the embodiment of interactive graphical user interface and implemented on the IEEE 14, 30, and 300 bus systems. The results showed reactive compensation has system wide-effect, provided readily accessible system status indicators, ensured seamless DERs interconnection through new islanding modes and enhanced VSC utilization. These outcomes may contribute

  5. 基于电压控制特性的电压源型多端直流/交流系统潮流求解%Power Flow Solving of VSC Multi-terminal DC/AC System Based on Voltage Control Characteristics

    Institute of Scientific and Technical Information of China (English)

    杨堤; 程浩忠; 姚良忠; 曾平良

    2016-01-01

    The voltage source converter based high voltage direct current (VSC-HVDC) transmission technology has good application prospects owing to its excellent controllability,voltage stability and good adaptability to power supply for load center,wind power accommodation,and power transmission among islands.The present research on power flow of VSC-HVDC system is mostly based on constant power control mode without considering the practical converter voltage control characteristics.In order to more accurately reflect the voltage control characteristics of VSC in the actual power grid,a voltage control model based on VSC is developed.As well,converter loss,AC filter,and converter capacity limit are considered in the power flow model.And a general power flow algorithm is proposed for power flow of the VSC based multi-terminal DC/AC system.Some cases with changed DC grid power injection,N -1 contingency and multi-terminal DC/AC system,are built and analyzed.The case analysis indicates that the power flow algorithm is able to reflect the voltage control ability of DC converters,while verifying the effectiveness,rationality and algorithm rapidity based on voltage control characteristics.%由于基于电压源型换流器的高压直流(VSC-HVDC)输电技术具有良好的可控性,对负荷中心供电、风电消纳、孤岛电力传输等适应能力强,电压稳定性好,因此具有良好的应用前景。当前对VSC-HVDC 系统主要基于定功率控制模式进行潮流计算,而很少考虑到实际的换流器电压控制能力。为了更加精确地反映实际电网中 VSC 的电压控制特性,文中建立了基于 VSC 的电压控制模型,考虑了换流器损耗、交流滤波器、换流器容量限制等的影响,并基于电压控制特性提出了 VSC多端直流/交流系统的通用潮流求解方法。对直流电网功率分布变化和 N -1故障以及多端直流/交流系统的潮流算例分析表明,所提的潮流算法能够反

  6. An isolated bridgeless AC-DC PFC converter using a LC resonant voltage doubler rectifier

    Science.gov (United States)

    Lee, Sin-woo; Do, Hyun-Lark

    2016-12-01

    This paper proposed an isolated bridgeless AC-DC power factor correction (PFC) converter using a LC resonant voltage doubler rectifier. The proposed converter is based on isolated conventional single-ended primary inductance converter (SEPIC) PFC converter. The conduction loss of rectification is reduced than a conventional one because the proposed converter is designed to eliminate a full-bridge rectifier at an input stage. Moreover, for zero-current switching (ZCS) operation and low voltage stresses of output diodes, the secondary of the proposed converter is designed as voltage doubler with a LC resonant tank. Additionally, an input-output electrical isolation is provided for safety standard. In conclusion, high power factor is achieved and efficiency is improved. The operational principles, steady-state analysis and design equations of the proposed converter are described in detail. Experimental results from a 60 W prototype at a constant switching frequency 100 kHz are presented to verify the performance of the proposed converter.

  7. Power Controllability of Three-phase Converter with Unbalanced AC Source

    DEFF Research Database (Denmark)

    Ma, Ke; Chen, Wenjie; Liserre, Marco

    2015-01-01

    Three-phase DC-AC power converters suffer from power oscillation and overcurrent problems in case of unbalanced AC source voltage that can be caused by grid/generator faults. Existing solutions to handle these problems are properly selecting and controlling the positive and negative sequence...... currents. In this work a new series of control strategies which utilize the zerosequence components are proposed to enhance the power control ability under this adverse condition. It is concluded that by introducing proper zero sequence current controls and corresponding circuit configurations, the power...... converter can enable more flexible control targets, achieving better performances in the delivered power and load current when suffering from unbalanced AC voltage....

  8. Voltage-sharing Characteristics of Porcelain Insulators for 750 kV AC Substation%Voltage-sharing Characteristics of Porcelain Insulators for 750 kV AC Substation

    Institute of Scientific and Technical Information of China (English)

    ZHANG Shi-ting; PENG Zong-ren; LIAO Jin tao

    2011-01-01

    Considering the complex environment in 750 kV AC substation, porcelain insulators have particular electric field and voltage distribution in comparison with those used in AC transmission line, meanwhile, the investigation of a typical 750 kV AC substation located in Lanzhou with ultraviolet imager (UVI) demonstrated that the corona dis- charge of some insulators is serious due to the improper structure design and installation, so research on porcelain insulators used in substation is needed. The three-dimensional finite element method (FEM) 750 kV AC substation calculation model was established to calculate electric field and voltage distribution of insulators, and the voltage distribution curves along insulators which are classified by type and suspension location were obtained using a novel FEM method which can effectively reduce the calculation amount without losing accuracy, meanwhile, the effect of the grading ring for improving voltage distribution of insulators was studied by adjusting the structure parameters of grad- ing ring. Consequently, an optimization structure of rings was proposed by improving the voltage distribution of insu- lator string and reducing the electric strength of grading ring for the purpose of restricting corona noise, and the on- site observations by UVI showed that the newly manufactured and installed grading ring could obviously avoid the occurrences of corona discharge which validates the optimization design. This paper proposed an effective method combi ning UVI observation and FEM calculation to study voltage-sharing characteristics of porcelain insulators, and the results can provide experiences and references for the design of 750 kV AC substation.

  9. Comparative Study of Breakdown Voltage of Mineral, Synthetic and Natural Oils and Based Mineral Oil Mixtures under AC and DC Voltages

    Directory of Open Access Journals (Sweden)

    Abderrahmane Beroual

    2017-04-01

    Full Text Available This paper deals with a comparative study of AC and DC breakdown voltages of based mineral oil mixtures with natural and synthetic esters mainly used in high voltage power transformers. The goal was to analyze the performances of oil mixtures from the dielectric withstand point of view and to predict the behavior of transformers originally filled with mineral oil and re-filled with synthetic or natural ester oils when emptied for maintenance. The study concerns mixtures based on 20%, 50%, and 80% of natural and synthetic ester oils. AC breakdown voltages were measured using a sphere-sphere electrode system according to IEC 60156 specifications; the same specification was adopted for DC measurements since there is no standard specifications for this voltage waveform. A statistical analysis of the mean values, standard deviations, and histograms of breakdown voltage data was carried out. The Normal and Weibull distribution functions were used to analyze the experimental data and the best function that the data followed was used to estimate the breakdown voltage with risk of 1%, 10%, and 50% probability. It was shown that whatever the applied voltage waveforms, ester oils always have a significantly higher breakdown voltage than mineral oil. The addition of only 20% of natural or synthetic ester oil was sufficient to considerably increase the breakdown voltage of mineral oil. The dielectric strength of such a mixture is much higher than that of mineral oil alone and can reach that of ester oils. From the point of view of dielectric strength, the mixtures constitute an option for improving the performance of mineral oil. Thus, re-filling of transformers containing up to 20% mineral oil residues with ester oils, does not present any problem; it is even advantageous when considering only the breakdown voltage. Under AC, the mixtures with natural ester always follow the behavior of vegetable oil alone. With the exception of the 20% mixture of natural

  10. Distributed Low Voltage Ride-Through Operation of Power Converters in Grid-Connected Microgrids under Voltage Sags

    DEFF Research Database (Denmark)

    Zhao, Xin; Meng, Lexuan; Dragicevic, Tomislav;

    2015-01-01

    the voltage in all phases at AC common bus. However, since the line admittances from each converter to point of common coupling (PCC) are not identical, the injected reactive power may not be equally shared. In order to achieve low voltage ride through (LVRT) capability along with a good power sharing...... accuracy, a hierarchical control strategy is proposed in this paper. Droop control and virtual impedance is applied in primary control loop while secondary control loop is based on dynamic consensus algorithm (DCA). Experiments are conducted to verify the effectiveness of the proposed control strategy....

  11. Investigating Enhancement Mode Gallium Nitride Power FETs in High Voltage, High Frequency Soft Switching Converters

    DEFF Research Database (Denmark)

    Nour, Yasser; Knott, Arnold; Jørgensen, Ivan Harald Holger

    2016-01-01

    An increased attention has been detected to develop smaller and lighter high voltage power converters in the range of 50V to 400V domain. The main applications for these converters are mainly focused for Power over Ethernet (PoE), LED lighting and AC adapters. This work will discuss a study...

  12. Investigating Enhancement Mode Gallium Nitride Power FETs in High Voltage, High Frequency Soft Switching Converters

    DEFF Research Database (Denmark)

    Nour, Yasser; Knott, Arnold; Jørgensen, Ivan Harald Holger

    2016-01-01

    An increased attention has been detected to develop smaller and lighter high voltage power converters in the range of 50V to 400V domain. The main applications for these converters are mainly focused for Power over Ethernet (PoE), LED lighting and AC adapters. This work will discuss a study of us...

  13. Voltage Stability Evaluation Incorporating Wind Power Intermittency

    Institute of Scientific and Technical Information of China (English)

    Libao SHI; Yang ZHAO; Yixin NI; Liangzhong YAO; Masoud BAZARGAN

    2013-01-01

    A simulation framework is proposed to evaluate the voltage stability of power systems incorporating wind power intermittency.Firstly,the power output modelings of three types of wind turbines are discussed.Secondly,the Jensen model is employed to simulate the wind farm with the wake effect.The Monte Carlo based technique is used to conduct the voltage stability evaluation incorporating the randomness of the wind speed based on the Weibull probability distribution.Thirdly,the relative sensitivity index (RSI) is calculated to identify weak buses during analysis.Finally,case studies with different simulation scenarios are carried out.Some statistical results involving weakness probability,expected value and variance of RSI as well as preliminary conclusions are drawn based on numerical simulation results.

  14. 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.

  15. Unified Power Quality Conditioner for voltage and current compensation

    OpenAIRE

    P.Annapandi; Dr.M.Rajaram

    2012-01-01

    This paper deals with a Unified Power Quality Conditioner (UPQC) for load balancing, power factorcorrection, voltage regulation, voltage and current harmonics mitigation, mitigation of voltage sag, swelland voltage dip in a three-phase three-wire distribution system for different combinations of linear and nonlinear loads.The unified power quality conditioner (UPQC) is a combination of back to back connected shunt and series active power filters (APFs) to a common DC link voltage, which compe...

  16. Isolated PWM DC-AC SICAM with an active capacitive voltage clamp[Pulse Density Modulated; Pulse Width Modulation

    Energy Technology Data Exchange (ETDEWEB)

    Ljusev, P.

    2004-03-15

    In this report an isolated PWM DC-AC SICAM with an active capacitive voltage clamp is presented. AC-DC power supply is implemented in its simplest form: diode rectifier followed by a medium-size charge-storage capacitors and possibly with an EMC filter on the mains entrance. Isolation from the AC mains is achieved using a high frequency (HF) transformer, whose voltages are not audio-modulated. The latter simplifies the design and is expected to have many advantages over the approach where the transformer voltages are modulated in regards to the audio signal reference. Input stage is built as a DC-AC inverter (push-pull, half-bridge or a full-bridge) and operated with 50% duty cycle, with all the challenges to avoid transformer saturation and obtain symmetrical operation. On the secondary side the output section is implemented as rectifier+inverter AC-AC stage, i.e. a true bidirectional bridge, which operation is aimed towards amplification of the audio signal. In order to solve the problem with the commutation of the load current, a dead time between the incoming and outgoing bidirectional switch is implemented, while a capacitive voltage clamp is used to keep the induced overvoltage to reasonable levels. The energy stored in the clamping capacitor is not wasted as in the dissipative clamps, but is rather transferred back to the primary side for further processing using an auxiliary isolated single-switch converter, i.e. an active clamping technique is used. (au)

  17. Study of High Voltage AC Underground Cable Systems

    DEFF Research Database (Denmark)

    da Silva, Filipe Miguel Faria; Bak, Claus Leth; Wiechowski, Wojciech T.

    2010-01-01

    High-Voltage cables are starting to be more often used to transmit electric energy at high-voltage levels, introducing in the electric grid phenomena that are uncommon when using Overhead Lines. Under the phenomena worthy of special attention are those related with the cable energisation and deen...

  18. High Efficiency Power Converter for Low Voltage High Power Applications

    DEFF Research Database (Denmark)

    Nymand, Morten

    , and remote power generation for light towers, camper vans, boats, beacons, and buoys etc. In chapter 2, a review of current state-of-the-art is presented. The best performing converters achieve moderately high peak efficiencies at high input voltage and medium power level. However, system dimensioning...

  19. Controlled Compact High Voltage Power Lines

    Directory of Open Access Journals (Sweden)

    Postolati V.

    2016-04-01

    Full Text Available Nowadays modern overhead transmission lines (OHL constructions having several significant differences from conventional ones are being used in power grids more and more widely. Implementation of compact overhead lines equipped with FACTS devices, including phase angle regulator settings (compact controlled OHL, appears to be one of the most effective ways of power grid development. Compact controlled AC HV OHL represent a new generation of power transmission lines embodying recent advanced achievements in design solutions, including towers and insulation, together with interconnection schemes and control systems. Results of comprehensive research and development in relation to 110–500kV compact controlled power transmission lines together with theoretical basis, substantiation, and methodological approaches to their practical application are presented in the present paper.

  20. Modular high voltage power supply for chemical analysis

    Science.gov (United States)

    Stamps, James F.; Yee, Daniel D.

    2008-07-15

    A high voltage power supply for use in a system such as a microfluidics system, uses a DC-DC converter in parallel with a voltage-controlled resistor. A feedback circuit provides a control signal for the DC-DC converter and voltage-controlled resistor so as to regulate the output voltage of the high voltage power supply, as well as, to sink or source current from the high voltage supply.

  1. Phase-sensitive detection of both inductive and non-inductive ac voltages in ferromagnetic resonance

    Science.gov (United States)

    Weiler, Mathias; Shaw, Justin M.; Nembach, Hans T.; Schoen, Martin A.; Boone, Carl T.; Silva, Thomas J.

    2014-03-01

    Spin pumping causes significant damping in ultrathin ferromagnetic/normal metal (NM) multilayers via spin-current generation of both dc and ac character in the NM system. While the nonlinear dc component has been investigated in detail by utilization of the inverse spin Hall effect (iSHE) in NMs, much less is known about the linear ac component that is presumably much larger in the small-excitation limit. We measured generated ac voltages in a wide variety of Permalloy/NM multilayers via vector-network-analyzer ferromagnetic resonance. We employ a custom, impedance-matched, broadband microwave coupler that features a ferromagnetic thin film reference resonator to accurately compare ac voltage amplitudes and phases between varieties of multilayers. By use of the fact that inductive and ac iSHE signals are phase-shifted by π/2, we find that inductive signals are major contributors in all investigated samples. It is only by comparison of the phase and amplitude of the recorded ac voltages between multiple samples that we can extract the non-inductive contributions due to spin-currents. Voltages due to the ac iSHE in Permalloy(10nm)/platinum(5nm) bilayers are weaker than inductive signals, in agreement with calculations based upon recent theoretical predictions. M.W. acknowledges financial support by the German Academic Exchange service (DAAD).

  2. Spin Backflow and ac Voltage Generation by Spin Pumping and the Inverse Spin Hall Effect

    Science.gov (United States)

    Jiao, HuJun; Bauer, Gerrit E. W.

    2013-05-01

    The spin current pumped by a precessing ferromagnet into an adjacent normal metal has a constant polarization component parallel to the precession axis and a rotating one normal to the magnetization. The former is now routinely detected as a dc voltage induced by the inverse spin Hall effect (ISHE). Here we compute ac ISHE voltages much larger than the dc signals for various material combinations and discuss optimal conditions to observe the effect. The backflow of spin is shown to be essential to distill parameters from measured ISHE voltages for both dc and ac configurations.

  3. Techniques for detecting proximity to voltage collapse in AC/DC systems

    Energy Technology Data Exchange (ETDEWEB)

    Canizares, Claudio A. [Escuela Politecnica Nacional, Quito (Ecuador); Long, Willis F.; Alvarado, Fernando L.; DeMarco, CChristopher L. [Wisconsin Univ., Madison, WI (United States)

    1992-12-31

    This paper describes three different techniques to detect proximity to voltage collapse (saddle-node bifurcation) in AC/DC systems; namely, direct (point of collapse) methods, continuation methods, and transient energy function methods. These techniques are compared among them, and also against the voltage sensitivity factor method using a 173 bus ac/dc test system. Various operational conditions are considered for this test system, so that transfer capabilities between areas and the effects of HVDC links can be analysed from the point of view of voltage collapse. 24 refs., 7 figs.

  4. Optimal coordinated voltage control of power systems

    Institute of Scientific and Technical Information of China (English)

    LI Yan-jun; HILL David J.; WU Tie-jun

    2006-01-01

    An immune algorithm solution is proposed in this paper to deal with the problem of optimal coordination of local physically based controllers in order to preserve or retain mid and long term voltage stability. This problem is in fact a global coordination control problem which involves not only sequencing and timing different control devices but also tuning the parameters of controllers. A multi-stage coordinated control scheme is presented, aiming at retaining good voltage levels with minimal control efforts and costs after severe disturbances in power systems. A self-pattern-recognized vaccination procedure is developed to transfer effective heuristic information into the new generation of solution candidates to speed up the convergence of the search procedure to global optima. An example of four bus power system case study is investigated to show the effectiveness and efficiency of the proposed algorithm, compared with several existing approaches such as differential dynamic programming and tree-search.

  5. 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.

  6. Advanced High Voltage Power Device Concepts

    CERN Document Server

    Baliga, B Jayant

    2012-01-01

    Advanced High Voltage Power Device Concepts describes devices utilized in power transmission and distribution equipment, and for very high power motor control in electric trains and steel-mills. Since these devices must be capable of supporting more than 5000-volts in the blocking mode, this books covers operation of devices rated at 5,000-V, 10,000-V and 20,000-V. Advanced concepts (the MCT, the BRT, and the EST) that enable MOS-gated control of power thyristor structures are described and analyzed in detail. In addition, detailed analyses of the silicon IGBT, as well as the silicon carbide MOSFET and IGBT, are provided for comparison purposes. Throughout the book, analytical models are generated to give a better understanding of the physics of operation for all the structures. This book provides readers with: The first comprehensive treatment of high voltage (over 5000-volts) power devices suitable for the power distribution, traction, and motor-control markets;  Analytical formulations for all the device ...

  7. A New Transformerless Single-Phase Buck-Boost AC Voltage Regulator

    Directory of Open Access Journals (Sweden)

    YALCIN, F.

    2016-05-01

    Full Text Available Voltage regulation is one of the important goals for electrical sources and consumers. In this paper a new transformerless single-phase AC voltage regulator based on buck-boost converter topology is presented. The regulator circuit has a simple structure using only two bidirectional active switches, one inductor and one capacitor. A closed loop control system is implemented for the proposed regulator operation. A control law depending on the instantaneous values of the regulator's real input and desired output voltage is obtained and supports the PI controller. The control law allows the controller to obtain efficient pulse width modulation (PWM switching duty ratio for the desired output voltage when the input voltage has surges or fluctuations and the output load is changed. An experimental laboratory setup has been implemented for the proposed AC voltage regulator. The obtained results demonstrate that the proposed topology is capable of and efficient for both bucking and boosting the input AC voltage to a high quality output voltage with a low total harmonic distortion (THD for different input voltage and load conditions.

  8. Multiagent voltage and reactive power control system

    Directory of Open Access Journals (Sweden)

    I. Arkhipov

    2014-12-01

    Full Text Available This paper is devoted to the research of multiagent voltage and reactive power control system development. The prototype of the system has been developed by R&D Center at FGC UES (Russia. The control system architecture is based on the innovative multiagent system theory application that leads to the achievement of several significant advantages (in comparison to traditional control systems implementation such as control system efficiency enhancement, control system survivability and cyber security.

  9. 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.

  10. Debugging on High-voltage Power Supply,Focusing Power Supply and Magnetic Field Power Supply

    Institute of Scientific and Technical Information of China (English)

    TU; Rui

    2015-01-01

    High-voltage power supply,focusing power supply and magnetic field power supply are the main parts of the power supply system of the EMIS(Electro-Magnetic Isotope Separator)supplying the ion source.In 2015,a high-voltage power supply,power supply for focusing and

  11. A Generalised Fault Protection Structure Proposed for Uni-grounded Low-Voltage AC Microgrids

    Science.gov (United States)

    Bui, Duong Minh; Chen, Shi-Lin; Lien, Keng-Yu; Jiang, Jheng-Lun

    2016-04-01

    This paper presents three main configurations of uni-grounded low-voltage AC microgrids. Transient situations of a uni-grounded low-voltage (LV) AC microgrid (MG) are simulated through various fault tests and operation transition tests between grid-connected and islanded modes. Based on transient simulation results, available fault protection methods are proposed for main and back-up protection of a uni-grounded AC microgrid. In addition, concept of a generalised fault protection structure of uni-grounded LVAC MGs is mentioned in the paper. As a result, main contributions of the paper are: (i) definition of different uni-grounded LVAC MG configurations; (ii) analysing transient responses of a uni-grounded LVAC microgrid through line-to-line faults, line-to-ground faults, three-phase faults and a microgrid operation transition test, (iii) proposing available fault protection methods for uni-grounded microgrids, such as: non-directional or directional overcurrent protection, under/over voltage protection, differential current protection, voltage-restrained overcurrent protection, and other fault protection principles not based on phase currents and voltages (e.g. total harmonic distortion detection of currents and voltages, using sequence components of current and voltage, 3I0 or 3V0 components), and (iv) developing a generalised fault protection structure with six individual protection zones to be suitable for different uni-grounded AC MG configurations.

  12. Dynamic Analysis of Power System Voltage Stability.

    Science.gov (United States)

    Gebreselassie, Assefa

    This thesis investigates the effects of loads and voltage regulators on the dynamic voltage stability of power systems. The analysis focuses on the interactions of machine flux dynamics with loads and voltage control devices. The results are based on eigenvalue analysis of the linearized models and time simulation of the nonlinear models, using models from the Power System Toolbox, a Matlab -based package for the simulation and small signal analysis of nonlinear power systems. The voltage stability analysis results are developed using a single machine single load system with typical machine and network parameters and the NPCC 10-machine system. Dynamic models for generators, exciters and loads are used. The generator is modeled with a pair of poles and one damper circuit in both the d-axis and the q-axis. Saturation effects are included in the model. The IEEE Type DC1 DC commutator exciter model is used for all the exciters. Five different types of loads: constant impedance, constant current, constant power, a first order induction motor model (slip model) and a third order induction motor model (slip-flux model) are considered. The modes of instability and the stability limits of the different representation of loads are examined for two different operating modes of the exciters. The first, when all the exciters are on automatic control and the second when some exciters are on manual control. Modal participation factors are used to determine the characteristics of the critical modes. The characteristics of the unstable modes are verified by performing time simulation of the nonlinear models. Oscillatory and non-oscillatory instabilities are experienced by load buses when all the exciters are on automatic control and some exciters are on manual control respectively, for loads which are predominantly constant power and induction motors. It is concluded that the mode of instability does not depend on the type of loads but on the operating condition of the exciters

  13. Analysis of energy processes in pulse converters of AC electric power

    Directory of Open Access Journals (Sweden)

    Kadatsky A.F.

    2015-02-01

    Full Text Available The article presents the analysis of energy processes in switched-mode AC-AC converters of buck, boost and buck-boost types. The mathematical model of energy processes is obtained. The mathematical model is generalized to DC-DC and AC-AC converters, to three basic types of converters and considers possibility of autotransformer inclusion of an inductor. It is shown that the use of bi-directional switches allows both DC and AC conversion of electrical energy regardless of the load type and also supports recuperation of electrical energy back to the source. It is shown that the maximum value of instant power in a load circuit in AC—AC converters exceeds twice the rated value of load power in comparison with DC—DC converters. It is shown that the energy capacity of an inductor in AC—AC converters exceeds twice the energy capacity of DC—DC converters at the identical rated power of conversion. It is shown that the energy capacity of an inductor in converters of buck and boost types depends on the ratio of input and output voltage. Also, the energy capacity of an inductor in converters of buck-boost type does not depend on the ratio of input and output voltage. It is shown that the energy capacity of an inductor in converters of buck and boost types is lower than the energy capacity of an inductor in the converter of buck-boost type.

  14. DC-bus voltage control of grid-connected voltage source converter by using space vector modulated direct power control under unbalanced network conditions

    DEFF Research Database (Denmark)

    Xiao, Lei; Huang, Shoudao; Lu, Kaiyuan

    2013-01-01

    Unbalanced grid voltage will cause large dc-bus voltage ripple and introduce high harmonic current components on the grid side. This will severely threaten the safety of the grid-connected voltage source converter (VSC) and consequently, affect the healthy operation condition of the load. In this......Unbalanced grid voltage will cause large dc-bus voltage ripple and introduce high harmonic current components on the grid side. This will severely threaten the safety of the grid-connected voltage source converter (VSC) and consequently, affect the healthy operation condition of the load....... In this study, a new proportional-integral-resonant (PI-RES) controller-based, space vector modulated direct power control topology is proposed to suppress the dc-bus voltage ripple and in the same time, controlling effectively the instantaneous power of the VSC. A special ac reactive power reference component...

  15. A direct power conversion topology for grid integrations of hybrid AC/DC resources

    DEFF Research Database (Denmark)

    Liu, Xiong; Loh, Poh Chiang; Wang, Peng;

    2012-01-01

    This paper proposes a multiple-input versatile matrix converter (VMC) to integrate hybrid ac/dc energy resources and storages to a power grid. The VMC is developed based on the indirect matrix converter (IMC) with its six-switch voltage source converter replaced by a nine-switch topology. The nine...

  16. EHV AC undergrounding electrical power performance and planning

    CERN Document Server

    Benato, Roberto

    2014-01-01

    Analytical methods of cable performance in EHV AC electrical power are discussed in this comprehensive reference. Descriptions of energization, power quality, cable safety constraints and more, guide readers in cable planning and power network operations.

  17. Wind-powered asynchronous AC/DC/AC converter system. [for electric power supply regulation

    Science.gov (United States)

    Reitan, D. K.

    1973-01-01

    Two asynchronous ac/dc/ac systems are modelled that utilize wind power to drive a variable or constant hertz alternator. The first system employs a high power 60-hertz inverter tie to the large backup supply of the power company to either supplement them from wind energy, storage, or from a combination of both at a preset desired current; rectifier and inverter are identical and operate in either mode depending on the silicon control rectifier firing angle. The second system employs the same rectification but from a 60-hertz alternator arrangement; it provides mainly dc output, some sinusoidal 60-hertz from the wind bus and some high harmonic content 60-hertz from an 800-watt inverter.

  18. Performance of two modified optimization techniques for power system voltage stability problems

    Directory of Open Access Journals (Sweden)

    S. Harish Kiran

    2016-09-01

    Full Text Available The development of optimization techniques in power system is to determine the sizing of Flexible AC Transmission System (FACTS devices such as Unified Power Flow Series Compensator (UPFC controller in improving the voltage stability and bus voltage margin. An attempt is made to modify the Particle Swarm Optimization (PSO and Artificial Bee Colony (ABC with Hybrid-Genetic Algorithm (H-GA for determination of sizing of the device. Fast Voltage Stability Index (FVSI is used to identify the location of the device to be connected. The proposed methods are implemented in IEEE 30 Bus system and its results are tabulated for each technique.

  19. Analytical approximation for AC losses in thin power-law superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Sokolovsky, V; Meerovich, V [Physics Department, Ben-Gurion University of the Negev, PO Box 653, Beer-Sheva, 84105 (Israel)

    2007-08-15

    AC losses in the superconducting parts of tapes and multifilamentary coated conductors that are subjected to AC magnetic fields are an important component of the total losses in such composites. The analytical expression for AC losses in a thin superconducting strip with a power-law voltage-current characteristic and critical current depending on a magnetic field is obtained for the case of asymptotically high perpendicular magnetic fields. The losses caused by closure currents are estimated. The results show that the Bean model gives significantly understated values for coated conductors. The applicability of the obtained expressions is analyzed.

  20. Guiding Principles in Selecting AC To DC Converters For Power Factor Corrections in AC Transmission System

    Directory of Open Access Journals (Sweden)

    Ibekwe B.E

    2014-10-01

    Full Text Available The ac to dc converters’ power factors correction in ac transmission system were investigated. The studies include: phase-controlled converter; pulse width modulated (PWM converter and ac input current shaped converter. Using Fourier series, power factors of these converters were calculated and simulated using MATLAB. The resulting curves are displayed in the hard copies for practical guides in the choice of converters; and comparatively, current shaped type is the best.

  1. Design and power management of an offshore medium voltage DC microgrid realized through high voltage power electronics technologies and control

    Science.gov (United States)

    Grainger, Brandon Michael

    The growth in the electric power industry's portfolio of Direct Current (DC) based generation and loads have captured the attention of many leading research institutions. Opportunities for using DC based systems have been explored in electric ship design and have been a proven, reliable solution for transmitting bulk power onshore and offshore. To integrate many of the renewable resources into our existing AC grid, a number of power conversions through power electronics are required to condition the equipment for direct connection. Within the power conversion stages, there is always a requirement to convert to or from DC. The AC microgrid is a conceptual solution proposed for integrating various types of renewable generation resources. The fundamental microgrid requirements include the capability of operating in islanding mode and/or grid connected modes. The technical challenges associated with microgrids include (1) operation modes and transitions that comply with IEEE1547 without extensive custom engineering and (2) control architecture and communication. The Medium Voltage DC (MVDC) architecture, explored by the University of Pittsburgh, can be visualized as a special type of DC microgrid. This dissertation is multi-faceted, focused on many design aspects of an offshore DC microgrid. The focal points of the discussion are focused on optimized high power, high frequency magnetic material performance in electric machines, transformers, and DC/DC power converters---all components found within offshore, power system architectures. A new controller design based upon model reference control is proposed and shown to stabilize the electric motor drives (modeled as constant power loads), which serve as the largest power consuming entities in the microgrid. The design and simulation of a state-of-the-art multilevel converter for High Voltage DC (HVDC) is discussed and a component sensitivity analysis on fault current peaks is explored. A power management routine is

  2. Power converters for medium voltage networks

    CERN Document Server

    Islam, Md Rabiul; Zhu, Jianguo

    2014-01-01

    This book examines a number of topics, mainly in connection with advances in semiconductor devices and magnetic materials and developments in medium and large-scale renewable power plant technologies, grid integration techniques and new converter topologies, including advanced digital control systems for medium-voltage networks. The book's individual chapters provide an extensive compilation of fundamental theories and in-depth information on current research and development trends, while also exploring new approaches to overcoming some critical limitations of conventional grid integration te

  3. Asymmetric operation of AC power transmission systems : the key to optimizing power system reliability and economics

    Energy Technology Data Exchange (ETDEWEB)

    Marceau, R.J. [University of Ontario Inst. of Technology, Oshawa, ON (Canada); McGillis, D.T. [McGill Univ., Montreal, PQ (Canada). Dept. of Electrical and Computer Engineering]|[Concordia Univ., Montreal, PQ (Canada). Dept. of Electrical and Computer Engineering; Sana, A.R.

    2006-07-01

    This book provides an invaluable tool for professionals working in the field of electrical engineering and applied science. It presents a simple and cost-effective strategy to operate alternating current (AC) power transmission systems more reliably and economically. Typically, bulk power transmission systems are operated symmetrically. When a problem such as a short-circuit occurs on a 3-phase line on an individual phase, all 3 phases are taken out of service. Such a strategy is fundamentally inefficient, given that most faults are single-line-to-ground faults. The more effective operating strategy presented in this book is based on the concept of asymmetric operation, which defines the operation of a 3-phase AC transmission line as 3 independently operated entities. As such, a 3-phase line can be operated with 1 or 2 phases out of service for single-line transmission corridors or with 1 , 2 or 3 phases out of service in the case of multiple-line corridors. This approach also maintains 3-phase symmetrical operation at its extremities, thereby protecting loads and power plants from undesirable voltages and currents. The overall integrity of 3-phase transmission is maintained in terms of power delivery, balanced voltages and currents even in the event of failures in part of the transmission system. The result is improved security. 67 refs., 42 tabs., 73 figs., 2 appendices.

  4. 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).

  5. Coordinated Control Scheme for Ancillary Services from Offshore Wind Power Plants to AC and DC Grids

    DEFF Research Database (Denmark)

    Sakamuri, Jayachandra N.; Altin, Müfit; Hansen, Anca Daniela;

    2016-01-01

    This paper proposes a new approach of providing ancillary services to AC and DC grids from offshore wind power plants (OWPPs), connected through multi-terminal HVDC network. A coordinated control scheme where OWPP’s AC grid frequency modulated according to DC grid voltage variations is used...... to detect and provide the ancillary service requirements of both AC and DC grids, is proposed in this paper. In particular, control strategies for onshore frequency control, fault ridethrough support in the onshore grid, and DC grid voltage control are considered. The proposed control scheme involves only...... local measurements and therefore avoids the need of communication infrastructure otherwise required for communication based control, and thus increases the reliability of the control system. The effectiveness of the proposed control scheme is demonstrated on a MTDC connected wind power system developed...

  6. Power Controllability of Three-phase Converter with Unbalanced AC Source

    DEFF Research Database (Denmark)

    Ma, Ke; Liserre, Marco; Blaabjerg, Frede

    2013-01-01

    Three-phase DC-AC power converters suffer from power oscillation and overcurrentt problems in case of unbalanced AC source voltage that can be caused by grid/generator faults. Existing solutions to handle these problems are properly selecting and controlling the positive and negative sequence...... converter can enable more flexible control targets, achieving better performances in the delivered power and load current when suffering from unbalanced AC sources....... currents. In this work a new series of control strategies which utilize the zero-sequence components are proposed to enhance the power control ability under this adverse conditions. It is concluded that by introducing proper zero sequence current controls and corresponding circuit configurations, the power...

  7. Mitigation Voltage Sag in Power System by Static Synchronous Compensator

    Directory of Open Access Journals (Sweden)

    Prechanon Kumkratug

    2010-01-01

    Full Text Available Problem statement: The disturbance in power system is unavoidable situation. It cause in voltage sag in power system. Approach: This study applied the STATCOM to mitigate voltage of the system. The mathematical model of power system equipped with a STATCOM is systematically derived. The presented mathematical model is shown how it effects on voltage sag improvement. The simulation results are tested on a Single Machine Infinite bus. The proposed method is equipped in sample system with severe disturbance. The variation voltage of the system without and with a STATCOM is plotted and compared. Results: It was found that the system without a STATCOM has high voltage variation especially voltage sags whereas with a STATCOM the system voltage has small voltage sages. Conclusion: From the simulation results, the STATCOM can mitigate voltage of power system.

  8. An estimator-based distributed voltage-predictive control strategy for ac islanded microgrids

    DEFF Research Database (Denmark)

    Wang, Yanbo; Chen, Zhe; Wang, Xiongfei

    2015-01-01

    This paper presents an estimator-based voltage predictive control strategy for AC islanded microgrids, which is able to perform voltage control without any communication facilities. The proposed control strategy is composed of a network voltage estimator and a voltage predictive controller for each...... control strategy is analyzed through small signal analysis method, from which the design guideline for the controller parameters is formulated. Furthermore, the robustness of the proposed voltage control strategy is investigated under a series of parameters uncertainties, including the line parameters...... perturbation, load parameters variation, different disturbance locations, LC filters perturbation, output impedances perturbation and DG unit fault. The simulation and experimental results show that the proposed control approach is able to perform offset-free voltage control without any communication links...

  9. An estimator-based distributed voltage-predictive control strategy for AC islanded microgrids

    DEFF Research Database (Denmark)

    Wang, Yanbo; Chen, Zhe; Wang, Xiongfei

    2015-01-01

    This paper presents an estimator-based voltage-predictive control strategy for ac islanded microgrids, which is able to perform voltage control without any communication facilities. The proposed control strategy is composed of a network voltage estimator and a voltage-predictive controller for each...... control strategy is analyzed through small-signal analysis method, from which the design guideline for the controller parameters is formulated. Furthermore, the robustness of the proposed voltage control strategy is investigated under a series of parameters uncertainties, including the line parameters...... perturbation, load parameters variation, different disturbance locations, LC filters perturbation, output impedances perturbation, and DG unit fault. The simulation and experimental results show that the proposed control approach is able to perform offset-free voltage control without any communication links...

  10. VOLTAGE STABILITY IMPROVEMENT IN POWER SYSTEM BY USING STATCOM

    Directory of Open Access Journals (Sweden)

    A.ANBARASAN

    2012-11-01

    Full Text Available Voltage stability problems usually occur in heavily loaded systems. Nowadays the power demand increases enormously, hence in a large interconnected power system network subject to stress conditions. This situation can be handled by increasing the generation or reducing the transmission losses. When the load increases suddenly, voltage magnitude also varies beyond the permissible voltage stability limit. But the voltage magnitude must be maintained within the limit for proper operation of the system. Hence, voltage stability must be improved by providing suitable reactive power compensation. The proposed work was analyzed using IEEE 14 bus test system. The STATCOM improves the voltage stability margin of the system.

  11. Electrical Model of Balanced AC HTS Power Cable

    Science.gov (United States)

    Zuijderduin, R.; Chevtchenko, O.; Smit, J. J.; Willén, D.; Melnik, I.; Geschiere, A.

    The future electricity grid will be more sustainable and it will have more power transmission and distribution capability with more electrical power added from decentralized sources on distribution level and from wind parks and other large sources on transmission level. More interconnections and more underground transmission and distribution will be put up. Use of high temperature superconducting (HTS) power cables provides solutions to many of the future grid problems caused by these trends. In this paper we present an electrical model of a balanced 6 km-long three phase triaxial HTS power cable for the Dutch project being developed by a consortium of Alliander, Ultera™ and TUD. The cable currents in all three phases are balanced by selecting proper twist pitches and insulation thickness. The paper focuses on determining inductances, capacitances and AC losses of the balanced cable. Using the developed model, we also determine the voltage drop as function of the cable length, the neutral current and the effect of the imbalanced capacitances on the current distribution of the Dutch distribution cable. The model is validated and it can be used for accurate simulation of the electrical behaviour of triaxial HTS cables in electrical grids.

  12. Analysis of three-phase rectifiers with AC-side switches and interleaved three-phase voltage-source converters

    Science.gov (United States)

    Miller, Stephanie Katherine Teixeira

    Of all the alternative and renewable energy sources, wind power is the fastest growing alternative energy source with a total worldwide capacity of over 93 GW as of the end of 2007. However, making wind energy a sustainable and reliable source of electricity doesn't come without its set of challenges. As the wind turbines increase in size and turbine technology moves towards off-shore wind farms and direct drive transmission, the need for a reliable and efficient power electronics interface to convert the variable-frequency variable-magnitude output of the wind turbine's generator into the fixed-frequency fixed-magnitude voltage of the utility grid is critical. This dissertation investigates a power electronics interface envisioned to operate with an induction generator-based variable-speed wind turbine. The research conclusions and the interface itself are applicable to a variety of applications, including uninterruptible power supplies, industrial drives, and power quality applications, among others. The three-phase PWM rectifiers with ac-side bidirectional switches are proposed as the rectification stage of the power electronics interface. Modulation strategies are proposed for the rectifiers and the operation of the rectifiers in conjunction with an induction generator is demonstrated. The viability of using these rectifiers in place of the standard three-phase voltage-source converter is analyzed by comparing losses and common-mode voltage generation of the two topologies. Parallel three-phase voltage-source converter modules operated in an interleaved fashion are proposed for the inversion stage of the power electronics interface. The interleaved three-phase voltage-source converters are analyzed by deriving analytical models for the common-mode voltage, ac phase current, and dc-link current to reveal their spectra and the harmonic cancellation effects of interleaving. The practical problem of low frequency circulating current in parallel voltage

  13. Statistical Distributions of Partial Discharges in Oil-paper Insulation Under AC-DC Combined Voltages

    Institute of Scientific and Technical Information of China (English)

    LI Jian; JIANG Tianyan; HE Zhiman; CHENG Changkui; BAO Lianwei

    2012-01-01

    The converter transformer is one of the most critical equipments in high-voltage direct current transmission systems.Valve-side windings have to withstand complex stresses combined of AC,DC,and pulsed voltages.Partial discharges(PDs) can thus easily occur in oil-impregnated paper insulation.The current paper presents the statistical phase-resolved distributions of partial discharges in oil-paper insulation under combined AC and DC voltage stress.First,the voltages in the converter transformer were analyzed.In the experiments,four artificial insulation defect models were designed to generate PD signals under AC-DC combined voltage stress detected by a Rogowski coil sensor.Histograms including the φ-q-n data of these PD signals were created.The variations of φ-q-n data generated by PDs in different insulation defect models were analyzed while increasing the test voltage.Experimental results showed that the PD phase-resolved distributions of different insulation defect models were different from one another.The findings of the current study are useful in further research on the mechanism and pattern recognition of PDs in converter transformers.

  14. A hybrid electromechanical solid state switch for ac power control

    Science.gov (United States)

    1972-01-01

    Bidirectional thyristor coupled to a series of actuator driven electromechanical contacts generates hybrid electromechanical solid state switch for ac power control. Device is useful in power control applications where zero crossover switching is required.

  15. Unified Power Quality Conditioner for voltage and current compensation

    Directory of Open Access Journals (Sweden)

    P.Annapandi

    2012-07-01

    Full Text Available This paper deals with a Unified Power Quality Conditioner (UPQC for load balancing, power factorcorrection, voltage regulation, voltage and current harmonics mitigation, mitigation of voltage sag, swelland voltage dip in a three-phase three-wire distribution system for different combinations of linear and nonlinear loads.The unified power quality conditioner (UPQC is a combination of back to back connected shunt and series active power filters (APFs to a common DC link voltage, which compensates voltage and current based distortions, independently.Using instantaneous active and reactive Power theory ,harmonic detection, reactive power compensation, voltage sag and swell have been simulated and the results are analyzed. The operation and capability of the proposed system was analyzed through simulations with MATLAB / SIMULINK.

  16. Chance-Constrained AC Optimal Power Flow for Distribution Systems With Renewables

    Energy Technology Data Exchange (ETDEWEB)

    DallAnese, Emiliano; Baker, Kyri; Summers, Tyler

    2017-09-01

    This paper focuses on distribution systems featuring renewable energy sources (RESs) and energy storage systems, and presents an AC optimal power flow (OPF) approach to optimize system-level performance objectives while coping with uncertainty in both RES generation and loads. The proposed method hinges on a chance-constrained AC OPF formulation where probabilistic constraints are utilized to enforce voltage regulation with prescribed probability. A computationally more affordable convex reformulation is developed by resorting to suitable linear approximations of the AC power-flow equations as well as convex approximations of the chance constraints. The approximate chance constraints provide conservative bounds that hold for arbitrary distributions of the forecasting errors. An adaptive strategy is then obtained by embedding the proposed AC OPF task into a model predictive control framework. Finally, a distributed solver is developed to strategically distribute the solution of the optimization problems across utility and customers.

  17. 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...

  18. Control voltage and power fluctuations when connecting wind farms

    Energy Technology Data Exchange (ETDEWEB)

    Berinde, Ioan, E-mail: ioan-berinde@yahoo.com; Bălan, Horia, E-mail: hbalan@mail.utcluj.ro; Oros, Teodora Susana, E-mail: teodoraoros-87@yahoo.com [Technical University of Cluj-Napoca, Romania, Faculty of Electrical Engineering, Department of Power Engineering and Management (Romania)

    2015-12-23

    Voltage, frequency, active power and reactive power are very important parameters in terms of power quality. These parameters are followed when connecting any power plant, the more the connection of wind farms. Connecting wind farms to the electricity system must not cause interference outside the limits set by regulations. Modern solutions for fast and automatic voltage control and power fluctuations using electronic control systems of reactive power flows. FACTS (Flexible Alternating Current Transmision System) systems, established on the basis of power electronic circuits ensure control of electrical status quantities to achieve the necessary transfer of power to the power grid. FACTS devices can quickly control parameters and sizes of state power lines, such as impedance line voltages and phase angles of the voltages of the two ends of the line. Their use can lead to improvement in power system operation by increasing the transmission capacity of power lines, power flow control lines, improved static and transient stability reserve.

  19. 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.

  20. Emergency operation of a 3AC 50Hz power grid in the Loetschberg base tunnel; Notbetrieb der Energieversorgung 3AC 50Hz im Loetschberg-Basistunnel

    Energy Technology Data Exchange (ETDEWEB)

    Stadelmann, M. [BLS AG, Ressort Bahnstrom, Bern (Switzerland); Boss, J. [BKW FMB Energie AG, Spiez (Switzerland)

    2007-11-15

    At latest after 90 min after tripping of the normal supply a special isle grid energized from the power plant of Kandergrund feeds the numerous users in the base tunnel with 3 AC 50 hz. This prevents them from damages and train operation can be assured immediately after return of normal grid voltage. (orig.)

  1. A new DC/AC boost transformerless converter in application of photovoltaic power generation

    DEFF Research Database (Denmark)

    Wei, Mo; Loh, Poh Chiang; Blaabjerg, Frede

    2011-01-01

    This paper presents a new DC/AC boost transformerless converter in the applications of photovoltaic (PV) power generation. A new circuit topology of single phase full bridge power inverter with additional DC/DC boost stage is proposed. The proposed topology overcomes two commonly existing...... shortcomings of transformerless PV system: namely one, the voltage generated sometimes low and insufficient to fulfill the load requirement; and two, there always leakage current flowing through parasitic capacitance between PV panel and ground. This configuration helps to boost the voltage at the PV side...

  2. Distributed Primary and Secondary Power Sharing in a Droop-Controlled LVDC Microgrid with Merged AC and DC Characteristics

    DEFF Research Database (Denmark)

    Peyghami Akhuleh, Saeed; Mokhtari, Hossein; Loh, Poh Chiang;

    2016-01-01

    in dc microgrids, which in most cases, are solved by a secondary control layer reinforced by an extensive communication network. To avoid such an infrastructure and its accompanied complications, this paper proposes an alternative droop scheme for low-voltage dc (LVDC) microgrid with both primary power......In an ac microgrid, a common frequency exists for coordinating active power sharing among droop-controlled sources. A common frequency is absent in a dc microgrid, leaving only the dc source voltages for coordinating active power sharing. That causes sharing error and poorer voltage regulation...... sharing and secondary voltage regulation merged. The main idea is to introduce a non-zero unifying frequency and a second power term to each dc source by modulating its converter with both a dc and a small ac signal. Two droop expressions can then be written for the proposed scheme, instead of the single...

  3. Engineering Design of the ITER AC/DC Power Supply System

    Energy Technology Data Exchange (ETDEWEB)

    Oh, B. H.; Lee, K. W.; Chang, D. S.; Jin, J. T.; Hwang, C. K.

    2010-02-15

    To design high power pulse power supplies, especially in huge power supplies have not designed till now, it is necessary to analyze a system's characteristics and relations with another systems as well as to know high voltage, high current control technologies. Contents of this project are; - Analysis of the changed designs of the AC/DC converters. - Setup of the PSIM model for the calculation of the junction temperature of the converter thyristors. - Finalize the converter's simulation modules and estimate the parallel number of an arm for each converter. - Fix the protection sequence and make a simulation. - Stability check of the power distribution system against the reactive power effect. - Design of small size hardware AC/DC converter. The results of these studies may used as one of references for practical designs of the power supplies and also used for developing Tokamak type fusion reactors in the future

  4. Characterization and assessment of voltage and power constraints of DFIG WT connected to a weak network

    DEFF Research Database (Denmark)

    Abulanwar, Elsayed; Hu, Weihao; Iov, Florin;

    2014-01-01

    This article thoroughly investigates the challenges and constraints raised by the integration of a Doubly-fed Induction generator wind turbine, DFIG WT, into an ac network of extensively varying parameters and very weak conditions. The objective is to mitigate the voltage variations at the point...... of common coupling, PCC, and maximize the wind power penetration into weak networks. As a basis of investigation, a simplified system model is utilized and the respective PCC voltage, active and reactive power stability issues are identified. Besides, a steady-state study for DFIG WT connected to a weak...

  5. Voltage stability in low voltage microgrids in aspects of active and reactive power demand

    Directory of Open Access Journals (Sweden)

    Parol Mirosław

    2016-03-01

    Full Text Available Low voltage microgrids are autonomous subsystems, in which generation, storage and power and electrical energy consumption appear. In the paper the main attention has been paid to the voltage stability issue in low voltage microgrid for different variants of its operation. In the introduction a notion of microgrid has been presented, and also the issue of influence of active and reactive power balance on node voltage level has been described. Then description of voltage stability issue has been presented. The conditions of voltage stability and indicators used to determine voltage stability margin in the microgrid have been described. Description of the low voltage test microgrid, as well as research methodology along with definition of considered variants of its operation have been presented further. The results of exemplary calculations carried out for the daily changes in node load of the active and reactive power, i.e. the voltage and the voltage stability margin indexes in nodes have been presented. Furthermore, the changes of voltage stability margin indexes depending on the variant of the microgrid operation have been presented. Summary and formulation of conclusions related to the issue of voltage stability in microgrids have been included at the end of the paper.

  6. Automatic Voltage Control (AVC) System under Uncertainty from Wind Power

    DEFF Research Database (Denmark)

    Qin, Nan; Abildgaard, Hans; Flynn, Damian

    2016-01-01

    An automatic voltage control (AVC) system maintains the voltage profile of a power system in an acceptable range and minimizes the operational cost by coordinating the regulation of controllable components. Typically, all of the parameters in the optimization problem are assumed to be certain...... and constant in the decision making process. However, for high shares of wind power, uncertainty in the decision process due to wind power variability may result in an infeasible AVC solution. This paper proposes a voltage control approach which considers the voltage uncertainty from wind power productions....... The proposed method improves the performance and the robustness of a scenario based approach by estimating the potential voltage variations due to fluctuating wind power production, and introduces a voltage margin to protect the decision against uncertainty for each scenario. The effectiveness of the proposed...

  7. A New Generalized Two-Stage Direct Power Conversion Topology to Independently Supply Multiple AC Loads from Multiple Power Grids with Adjustable Power Loading

    DEFF Research Database (Denmark)

    Klumpner, Christian; Blaabjerg, Frede

    2004-01-01

    Normally, a power converter has one supply port to connect to the power grid and one output port to connect to an AC load that requires variable voltage and variable frequency. Converter topologies with multiple output ports, the so-called multi-drive converters are also used in order to share......) and continuously adjust these power fractions will become a desired feature. This paper presents a generalized Direct Power Converter topology, which is able to connect to multiple AC supplies proving complete decoupling and no circulating power between the input ports and to independently control multiple AC...... the cost of an active front-end rectifier. As the trend on the energy market is towards deregulation, new converter topologies are needed to allow independent producers/consumers to connect to multiple distribution grids in order to minimize the electricity price. Having the possibility to adjust smoothly...

  8. A comparative study of different transformer connections for railway power supply- mitigation of voltage unbalance

    DEFF Research Database (Denmark)

    Firat, Gurkan; Yang, Guangya; Ali Hussain Al-Ali, Haider

    2015-01-01

    The railway represents a large power consumer that can cause uneven loading of the phases in the high voltage grid. These unbalanced loads supplied by the utility may lead to voltage unbalance problems in the system and thereby affects the other consumers connected to the same network. It is fact...... that, voltage unbalance appears mainly as a result of unbalanced currents at the points of common coupling drawn by unevenly distributed loads. Because of a significant amount of negative sequence current injected to the system, the power system components will suffer from consequent negative effects...... such as overheating, additional losses of lines and transformers, interference with communication systems etc. This paper presents a comparative study of some transformer connections which commonly used in railway supplying AC traction loads, for voltage unbalance mitigations. Simulations for comparison...

  9. Flow reversal at low voltage and low frequency in a microfabricated ac electrokinetic pump

    DEFF Research Database (Denmark)

    Gregersen, Misha Marie; Olesen, Laurits Højgaard; Brask, Anders

    2007-01-01

    Microfluidic chips have been fabricated in Pyrex glass to study electrokinetic pumping generated by a low-voltage ac bias applied to an in-channel asymmetric metallic electrode array. A measurement procedure has been established and followed carefully resulting in a high degree of reproducibility...... of the measurements over several days. A large coverage fraction of the electrode array in the microfluidic channels has led to an increased sensitivity allowing for pumping measurements at low bias voltages. Depending on the ionic concentration a hitherto unobserved reversal of the pumping direction has been...

  10. Effect of embedded voltage source converter on power system oscillation damping

    Institute of Scientific and Technical Information of China (English)

    R; DUNN

    2010-01-01

    This paper presents the damping torque analysis of power system oscillation stability as affected by the dynamic and control functions of an embedded voltage source converter(VSC).The objective of the study is to explain why and how the dynamic and basic control functions of the embedded VSC,ac and dc voltage regulation,provide damping to power system oscillations.The most important conclusion obtained in the paper is that both the dynamics and the dc voltage control of the VSC contribute a variable damping torque,which can be positive or negative,at different levels of system load conditions.More positive damping torque can be provided by the VSC at a heavier load condition.There exists a point of system load condition where the VSC provides no damping torque to power system oscillation hence dose not impose any influence on power system oscillation stability.The VSC studied in the paper can be the power-electronics-based interface of various FACTS(flexible ac transmission systems) devices,energy storage systems and renewable power generation units,although the focus of the discussion presented in this paper is the effect of the dynamics and basic control functions of the VSC themselves on power system oscillation damping.To demonstrate the analytical conclusions obtained in the paper,results of eigenvalue computation and nonlinear simulation of an example power system with STATCOM(static synchronous compensator) are given.

  11. Design of Three Phase Solar-Based 4.5kw Ac Power Inverter Station

    Directory of Open Access Journals (Sweden)

    Dr.J.C. Onuegbu

    2013-07-01

    Full Text Available The design model of a 4.50Kilowatt, 3-phase, 50 hertz solar-based power generating station was examined by the paper. The power station is a dual source input generating station using 8 series connected 100A, 12V batteries per phase as backup, the solar panels being the main frame. An inverter of 12Volt direct current input voltage was incorporated to supply an output of 3-phase, 220Volts and 50 hertz alternating current. A charging circuit was installed to monitor charging level and to preserve the accumulator’s life span. The paper also looked into the solar-based power station component design model. The batteries therein are back-up and the system will ensure 24-hours reliable power supply. The setup has a normally closed switching relay ready to pickup the auxiliary battery supply within a few milliseconds after the solar source voltage drops below a stipulated level. The three phase a.c. voltage was achieved using standby on-line circuit with cascaded 741-based flip-flop at the base of the transistor drivers of the 3-phase power transformer. This model circuit reduced the load on each phase winding and facilitated reliable and uninterruptible power supply. The delta-wyeconnected transformer will guarantee proper phase shift of 120 degrees that will emulate alternating current voltage similar to the conventional generator voltage.

  12. Power factor control system for ac induction motors

    Science.gov (United States)

    Nola, F. J. (Inventor)

    1981-01-01

    A power control circuit for an induction motor is disclosed in which a servo loop is used to control power input by controlling the power factor of motor operation. The power factor is measured by summing the voltage and current derived square wave signals.

  13. Test Results from a Simulated High Voltage Lunar Power Transmission Line

    Science.gov (United States)

    Birchenough, Arthur; Hervol, David

    2008-01-01

    The Alternator Test Unit (ATU) in the Lunar Power System Facility (LPSF) located at the NASA Glenn Research Center (GRC) in Cleveland, OH was modified to simulate high voltage transmission capability. The testbed simulated a 1 km transmission cable length from the ATU to the LPSF using resistors and inductors installed between the distribution transformers. Power factor correction circuitry was used to compensate for the reactance of the distribution system to improve the overall power factor. This test demonstrated that a permanent magnet alternator can successfully provide high frequency AC power to a lunar facility located at a distance.

  14. Test Results From a Simulated High-Voltage Lunar Power Transmission Line

    Science.gov (United States)

    Birchenough, Arthur; Hervol, David

    2008-01-01

    The Alternator Test Unit (ATU) in the Lunar Power System Facility (LPSF) located at the NASA Glenn Research Center (GRC) in Cleveland, Ohio was modified to simulate high-voltage transmission capability. The testbed simulated a 1 km transmission cable length from the ATU to the LPSF using resistors and inductors installed between the distribution transformers. Power factor correction circuitry was used to compensate for the reactance of the distribution system to improve the overall power factor. This test demonstrated that a permanent magnet alternator can successfully provide high-frequency ac power to a lunar facility located at a distance.

  15. A novel wireless power and data transmission AC to DC converter for an implantable device.

    Science.gov (United States)

    Liu, Jhao-Yan; Tang, Kea-Tiong

    2013-01-01

    This article presents a novel AC to DC converter implemented by standard CMOS technology, applied for wireless power transmission. This circuit combines the functions of the rectifier and DC to DC converter, rather than using the rectifier to convert AC to DC and then supplying the required voltage with regulator as in the transitional method. This modification can reduce the power consumption and the area of the circuit. This circuit also transfers the loading condition back to the external circuit by the load shift keying(LSK), determining if the input power is not enough or excessive, which increases the efficiency of the total system. The AC to DC converter is fabricated with the TSMC 90nm CMOS process. The circuit area is 0.071mm(2). The circuit can produce a 1V DC voltage with maximum output current of 10mA from an AC input ranging from 1.5V to 2V, at 1MHz to 10MHz.

  16. Quadratic models of AC-DC power flow and optimal reactive power flow with HVDC and UPFC controls

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Juan; Yan, Wei; Wen, Lili [The Key Laboratory of High Voltage Engineering and Electrical New Technology, Ministry of Education, Electrical Engineering College of Chongqing University, Chongqing 400030 (China); Li, Wenyuan [British Columbia Transmission Corporation (BCTC), Suite 1100, Four Bentall Center, 1055 Dunsmuir Street, P.O. Box 49260, Vancouver, BC (Canada)

    2008-03-15

    Quadratic models of power flow (PF) and optimal reactive power flow (ORPF) for AC-DC power systems are proposed in the paper. Voltage magnitudes at the two sides of ideal converter transformers are used as additional state variables to build the quadratic models. Effects of converter controls on equality constraints are considered. The quadratic expression of unified power flow controller (UPFC) is also developed and incorporated into the proposed models. The proposed PF model retaining nonlinearity has a better convergence feature and requires less CPU time compared to traditional PF models. The Hessian matrices in the quadratic AC-DC ORPF model are constant and need to be calculated only once in the entire optimization process, which speeds up the calculation greatly. Results obtained from the four IEEE test systems and an actual utility system indicate that the proposed quadratic models achieve a superior performance than conventional models. (author)

  17. Power converters and AC electrical drives with linear neural networks

    CERN Document Server

    Cirrincione, Maurizio

    2012-01-01

    The first book of its kind, Power Converters and AC Electrical Drives with Linear Neural Networks systematically explores the application of neural networks in the field of power electronics, with particular emphasis on the sensorless control of AC drives. It presents the classical theory based on space-vectors in identification, discusses control of electrical drives and power converters, and examines improvements that can be attained when using linear neural networks. The book integrates power electronics and electrical drives with artificial neural networks (ANN). Organized into four parts,

  18. Active Power Regulation based on Droop for AC Microgrid

    DEFF Research Database (Denmark)

    Li, Chendan; Coelho, Ernane A. A.; Firoozabadi, Mehdi Savaghebi

    2015-01-01

    In this paper, two different control strategies are proposed to address the active power regulation issue in AC microgrids. The principle of power regulation in the droop controller is firstly introduced. Frequency scheduling and droop gain scheduling on top of droop control is proposed to succes......In this paper, two different control strategies are proposed to address the active power regulation issue in AC microgrids. The principle of power regulation in the droop controller is firstly introduced. Frequency scheduling and droop gain scheduling on top of droop control is proposed...

  19. Unique Power Dense, Configurable, Robust, High-Voltage Power Supplies Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Princeton Power will develop and deliver three small, lightweight 50 W high-voltage power supplies that have a configurable output voltage range from 500 to 50 kVDC....

  20. Conventional P-ω/Q-V Droop Control in Highly Resistive Line of Low-Voltage Converter-Based AC Microgrid

    DEFF Research Database (Denmark)

    Hou, Xiaochao; Sun, Yao; Yuan, Wenbin

    2016-01-01

    In low-voltage converter-based alternating current (AC) microgrids with resistive distribution lines, the P-V droop with Q-f boost (VPD/FQB) is the most common method for load sharing. However, it cannot achieve the active power sharing proportionally. To overcome this drawback, the conventional P......-ω/Q-V droop control is adopted in the low-voltage AC microgrid. As a result, the active power sharing among the distributed generators (DGs) is easily obtained without communication. More importantly, this study clears up the previous misunderstanding that conventional P-ω/Q-V droop control is only applicable...... to microgrids with highly inductive lines, and lays a foundation for the application of conventional droop control under different line impedances. Moreover, in order to guarantee the accurate reactive power sharing, a guide for designing Q-V droop gains is given, and virtual resistance is adopted to shape...

  1. Voltage stability and controllability indices for multimachine power systems

    Energy Technology Data Exchange (ETDEWEB)

    Vournas, C.D. [National Technical Univ., Athens (Greece). Electrical Energy Systems Lab.

    1995-08-01

    This paper presents a voltage stability index (VSI) and a voltage controllability index (VCI), related to the eigenvalues of mxm matrices in a multimachine power system made up of m synchronous generators and a number of infinite buses. System loads can have an arbitrary voltage sensitivity described by generalized voltage exponents. These nonlinear loads are linearized around an operating point and incorporated into a modified admittance matrix, which is subsequently reduced to the generator terminals using an efficient algorithm and sparsity techniques. The indices proposed are tested in a practical system and it is demonstrated that they provide a timely warning during a sequence of events leading to voltage collapse.

  2. Low-Voltage Ultra-Low-Power Current Conveyor Based on Quasi-Floating Gate Transistors

    Directory of Open Access Journals (Sweden)

    F. Khateb

    2012-06-01

    Full Text Available The field of low-voltage low-power CMOS technology has grown rapidly in recent years; it is an essential prerequisite particularly for portable electronic equipment and implantable medical devices due to its influence on battery lifetime. Recently, significant improvements in implementing circuits working in the low-voltage low-power area have been achieved, but circuit designers face severe challenges when trying to improve or even maintain the circuit performance with reduced supply voltage. In this paper, a low-voltage ultra-low-power current conveyor second generation CCII based on quasi-floating gate transistors is presented. The proposed circuit operates at a very low supply voltage of only ±0.4 V with rail-to-rail voltage swing capability and a total quiescent power consumption of mere 9.5 µW. Further, the proposed circuit is not only able to process the AC signal as it's usual at quasi-floating gate transistors but also the DC which extends the applicability of the proposed circuit. In conclusion, an application example of the current-mode quadrature oscillator is presented. PSpice simulation results using the 0.18 µm TSMC CMOS technology are included to confirm the attractive properties of the proposed circuit.

  3. Capturing power at higher voltages from arrays of microbial fuel cells without voltage reversal

    KAUST Repository

    Kim, Younggy

    2011-01-01

    Voltages produced by microbial fuel cells (MFCs) cannot be sustainably increased by linking them in series due to voltage reversal, which substantially reduces stack voltages. It was shown here that MFC voltages can be increased with continuous power production using an electronic circuit containing two sets of multiple capacitors that were alternately charged and discharged (every one second). Capacitors were charged in parallel by the MFCs, but linked in series while discharging to the circuit load (resistor). The parallel charging of the capacitors avoided voltage reversal, while discharging the capacitors in series produced up to 2.5 V with four capacitors. There were negligible energy losses in the circuit compared to 20-40% losses typically obtained with MFCs using DC-DC converters to increase voltage. Coulombic efficiencies were 67% when power was generated via four capacitors, compared to only 38% when individual MFCs were operated with a fixed resistance of 250 Ω. The maximum power produced using the capacitors was not adversely affected by variable performance of the MFCs, showing that power generation can be maintained even if individual MFCs perform differently. Longer capacitor charging and discharging cycles of up to 4 min maintained the average power but increased peak power by up to 2.6 times. These results show that capacitors can be used to easily obtain higher voltages from MFCs, allowing for more useful capture of energy from arrays of MFCs. © 2011 The Royal Society of Chemistry.

  4. A new low cost single phase ac-ac power line conditioner

    Directory of Open Access Journals (Sweden)

    Santosh Sonar 1, Tanmoy Maity

    2012-12-01

    Full Text Available The paper presents a comparative study of three topologies of recently developed voltage-fed z-source inverter (ZSI such as simple ZSI, quasi-ZSI and trans-ZSI. Different control techniques, proposed earlier for simple ZSI such as simple boost control, maximum boost control and constant boost control, have been applied here for all type of ZSI topologies. The detailed comparative evaluation of all topologies under different PWM techniques is done as power line conditioner. For the common boost factor and modulation index, the output voltage, line harmonics profile of all ZSIs powered by same source and load are evaluated. The operating principles are analysed and the boost factor, voltage gain, duty ratio and voltage stress across the switches are derived. Also the relationships among them are compared even under variable circuit parameters and switch frequency. The results would help to select suitable topology and PWM switching method for power line conditioner application.

  5. High performance AC–DC control power supply for low voltage ride through inverters

    Indian Academy of Sciences (India)

    K Saichand; Akshay Kumrawat; Vinod John

    2016-02-01

    This paper presents a control power supply (CPS) design which is used to feed power to the subsystems of a power converter. The CPS design presented here maintains a constant 24Vdc output even over a wide (90Vrms to 270Vrms ) ac voltage variation at its input for a High Power Converter (HPC). The circuit design and closed loop control design of such a CPS are presented. During starting, the power supply to the control circuitry of the CPS in turn is obtained using a separate start-up power supply. The various design issues and details of the on-board power supply and start-up power circuit to ensure the reliable start-up and shut down of the CPS are analyzed. The CPS was tested for wide input voltage range (vin) and the performance validates the design. The CPS has also been tested for an input side voltage sag and its performance allows the HPC to meet the low voltage ride-through requirements.

  6. Study of Power Flow Algorithm of AC/DC Distribution System including VSC-MTDC

    Directory of Open Access Journals (Sweden)

    Haifeng Liang

    2015-08-01

    Full Text Available In recent years, distributed generation and a large number of sensitive AC and DC loads have been connected to distribution networks, which introduce a series of challenges to distribution network operators (DNOs. In addition, the advantages of DC distribution networks, such as the energy conservation and emission reduction, mean that the voltage source converter based multi-terminal direct current (VSC-MTDC for AC/DC distribution systems demonstrates a great potential, hence drawing growing research interest. In this paper, considering losses of the reactor, the filter and the converter, a mathematical model of VSC-HVDC for the load flow analysis is derived. An AC/DC distribution network architecture has been built, based on which the differences in modified equations of the VSC-MTDC-based network under different control modes are analyzed. In addition, corresponding interface functions under five control modes are provided, and a back/forward iterative algorithm which is applied to power flow calculation of the AC/DC distribution system including VSC-MTDC is proposed. Finally, by calculating the power flow of the modified IEEE14 AC/DC distribution network, the efficiency and validity of the model and algorithm are evaluated. With various distributed generations connected to the network at appropriate locations, power flow results show that network losses and utilization of transmission networks are effectively reduced.

  7. Power flow analysis for DC voltage droop controlled DC microgrids

    DEFF Research Database (Denmark)

    Li, Chendan; Chaudhary, Sanjay; Dragicevic, Tomislav

    2014-01-01

    This paper proposes a new algorithm for power flow analysis in droop controlled DC microgrids. By considering the droop control in the power flow analysis for the DC microgrid, when compared with traditional methods, more accurate analysis results can be obtained. The algorithm verification...... is carried out by comparing the calculation results with detailed time domain simulation results. With the droop parameters as variables in the power flow analysis, their effects on power sharing and secondary voltage regulation can now be analytically studied, and specialized optimization in the upper level...... control can also be made accordingly. Case studies on power sharing and secondary voltage regulation are carried out using proposed power flow analysis....

  8. Study of UPFC Optimal Location Considering Loss Reduction and Improvement of Voltage Stability and Power Flow

    Directory of Open Access Journals (Sweden)

    Islam Youcef DJILANI KOBIBI

    2014-02-01

    Full Text Available With the increase in power demand, operation and planning of large interconnected power system are becoming more complex, so power system will become less secure and stable. A new concept of Flexible AC Transmission system (FACTS brought radical changes in the power system operation and control. FACTS controllers narrow the gap between the no controlled and the controlled power system mode of operation, by providing additional degrees of freedom to control power flows and voltages. Unified Power Flow Controller (UPFC is a versatile FACTS device which can independently or simultaneously control the active power, the reactive power, and the bus voltage to which it is connected. The main purpose of this paper is to identify the optimal location of the Unified Power Flow Controller (UPFC in order to minimize active power losses and improve the voltage profiles using the injection model of the (UPFC in Newton-Raphson load flow algorithm, in an IEEE- 14, 30, 57, 118, 300 Bus test systems.

  9. Investigations of surface characterization of silicone rubber due to tracking phenomena under a.c. and d.c. voltages

    Indian Academy of Sciences (India)

    Uma Maheswar Rao; S S M S Abdul Majeed; C Venkataseshaiah; R Sarathi

    2002-11-01

    In the present work, tracking phenomena has been studied with silicone rubber material under the a.c. and d.c. voltages following IEC-587 standards. The surface condition of the tracked zone was analysed using wide angle X-ray diffraction (WAXD) and thermogravimetric differential thermal analysis (TG–DTA) studies. The tracking time was different for a.c. and d.c. voltages.

  10. High Input Voltage, Silicon Carbide Power Processing Unit Performance Demonstration

    Science.gov (United States)

    Bozak, Karin E.; Pinero, Luis R.; Scheidegger, Robert J.; Aulisio, Michael V.; Gonzalez, Marcelo C.; Birchenough, Arthur G.

    2015-01-01

    A silicon carbide brassboard power processing unit has been developed by the NASA Glenn Research Center in Cleveland, Ohio. The power processing unit operates from two sources: a nominal 300 Volt high voltage input bus and a nominal 28 Volt low voltage input bus. The design of the power processing unit includes four low voltage, low power auxiliary supplies, and two parallel 7.5 kilowatt (kW) discharge power supplies that are capable of providing up to 15 kilowatts of total power at 300 to 500 Volts (V) to the thruster. Additionally, the unit contains a housekeeping supply, high voltage input filter, low voltage input filter, and master control board, such that the complete brassboard unit is capable of operating a 12.5 kilowatt Hall effect thruster. The performance of the unit was characterized under both ambient and thermal vacuum test conditions, and the results demonstrate exceptional performance with full power efficiencies exceeding 97%. The unit was also tested with a 12.5kW Hall effect thruster to verify compatibility and output filter specifications. With space-qualified silicon carbide or similar high voltage, high efficiency power devices, this would provide a design solution to address the need for high power electric propulsion systems.

  11. Optimization of power systems with voltage security constraints

    Science.gov (United States)

    Rosehart, William Daniel

    As open access market principles are applied to power systems, significant changes in their operation and control are occurring. In the new marketplace, power systems are operating under higher loading conditions as market influences demand greater attention to operating cost versus stability margins. Since stability continues to be a basic requirement in the operation of any power system, new tools are being considered to analyze the effect of stability on the operating cost of the system, so that system stability can be incorporated into the costs of operating the system. In this thesis, new optimal power flow (OPF) formulations are proposed based on multi-objective methodologies to optimize active and reactive power dispatch while maximizing voltage security in power systems. The effects of minimizing operating costs, minimizing reactive power generation and/or maximizing voltage stability margins are analyzed. Results obtained using the proposed Voltage Stability Constrained OPF formulations are compared and analyzed to suggest possible ways of costing voltage security in power systems. When considering voltage stability margins the importance of system modeling becomes critical, since it has been demonstrated, based on bifurcation analysis, that modeling can have a significant effect of the behavior of power systems, especially at high loading levels. Therefore, this thesis also examines the effects of detailed generator models and several exponential load models. Furthermore, because of its influence on voltage stability, a Static Var Compensator model is also incorporated into the optimization problems.

  12. Three Phase Two Leg Neutral Point Clamped Converter with output DC Voltage Regulation and Input Power Factor Correction

    Directory of Open Access Journals (Sweden)

    Bogimi Sirisha

    2012-03-01

    Full Text Available In this paper, a three-phase two leg neutral point clamped (NPC converter is presented for power factor correction and dc-link voltage regulation. The adopted converter has simpler circuit configuration and less number of power switches compared to three-level PWM converter. In this circuit configuration, only eight power switches and four clamping diodes with voltage stress of half the dc bus voltage are used. A simplified space vector pulse width modulation scheme (SVPWM is also adopted to track the line current commands. A reference voltage vector is generated on the ac terminal for drawing the sinusoidal line currents with unity power factor. This algorithm reduces the time required to calculate the switching time durations of voltage vectors. The simulation results have been presented to verify the validity and effectiveness of the proposed control strategy.

  13. Bidirectional Five-Level Power Processing Interface for Low Voltage Battery Energy Storage System

    Science.gov (United States)

    Huang, Jain-Yi; Jou, Hurng-Liahng; Wu, Kuen-Der; Lin, You-Si; Wu, Jinn-Chang

    A bidirectional five-level power processing interface for low voltage battery energy storage system (BESS) is developed in this paper. This BESS consists of a bidirectional five-level DC-AC converter, a bidirectional dual boost/buck DC-DC converter and a battery set. This five-level DC-AC converter includes a bidirectional full-bridge converter and a bidirectional dual buck DC-DC converter. The five-level power processing interface can charge power to the battery set form the utility or discharge the power from the battery set to the utility depending on the demanded operation of user. A hardware prototype is developed to verify the performance of this BESS. Experimental results show the performance of the developed BESS is as expected.

  14. Djungle power. A more remote AC bus

    Energy Technology Data Exchange (ETDEWEB)

    Boehnke, Heinz W. [Technosol, Jork (Germany)

    2010-07-01

    The Dzanga-Sangha Reserve in the Central African Republic is probably one of the world's most remote protected rainforest areas, much to the benefit of the rare species of lowland gorilla, forest elephant and local pygmy population Ba'Aka. The park is co-managed by the ''WWF-World Wide Fund for Nature'' with sponsoring from the German Regenwald-Stiftung. In 2008 wwf decided to switch from the old, failing generator supply to a solar hybrid mini-grid, along with stringent measures of energy conservation and management. After a careful energy audit Technosol designed an AC-bus system with a 22 kWp PV generator which should overcome the dependency on the old generators and their fuel demands. For 15 buildings, an entirely new distribution network was installed, state of the art energy saving devices introduced and an energy metering system deviced. The installation is operating since August 2009. In such remote locations, the reliability of the AC-bus over other generator-based solutions will be demonstrated and with the support of international organisations like the wwf the practical application of solar hybrid supply becomes a landmark of sustainable energy concepts. (orig.)

  15. 21 CFR 880.6320 - AC-powered medical examination light.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false AC-powered medical examination light. 880.6320... Miscellaneous Devices § 880.6320 AC-powered medical examination light. (a) Identification. An AC-powered medical examination light is an AC-powered device intended for medical purposes that is used to illuminate...

  16. Convex Relaxation of Power Dispatch for Voltage Stability Improvement

    DEFF Research Database (Denmark)

    Pedersen, Andreas Søndergaard; Blanke, Mogens; Jóhannsson, Hjörtur

    2015-01-01

    A method for enhancing the voltage stability ofa power system is presented in this paper. The method isbased on a stability-constrained optimal power flow approach,where dispatch is done such that a maximum L-index isminimised for all load busses in a transmission grid. It isshown that optimal...... dispatch is obtainable with enhancedmargins for voltage stability using a semidefinite relaxation ofthe optimal power flow problem, and that this problem canbe formulated as semidefinite program with a quasi-convexobjective. Numerical tests are performed on the IEEE-30 busand BPA systems. The feasibility...... of the method is demonstratedthrough demonstrating that improved voltage stability marginsare obtained for both systems....

  17. Working group report on advanced high-voltage high-power and energy-storage space systems

    Science.gov (United States)

    Cohen, H. A.; Cooke, D. L.; Evans, R. W.; Hastings, D.; Jongeward, G.; Laframboise, J. G.; Mahaffey, D.; Mcintyre, B.; Pfizer, K. A.; Purvis, C.

    1986-01-01

    Space systems in the future will probably include high-voltage, high-power energy-storage and -production systems. Two such technologies are high-voltage ac and dc systems and high-power electrodynamic tethers. The working group identified several plasma interaction phenomena that will occur in the operation of these power systems. The working group felt that building an understanding of these critical interaction issues meant that several gaps in our knowledge had to be filled, and that certain aspects of dc power systems have become fairly well understood. Examples of these current collection are in quiescent plasmas and snap over effects. However, high-voltage dc and almost all ac phenomena are, at best, inadequately understood. In addition, there is major uncertainty in the knowledge of coupling between plasmas and large scale current flows in space plasmas. These gaps in the knowledge are addressed.

  18. A Coordinated Control for Photovoltaic Generators and Energy Storages in Low-Voltage AC/DC Hybrid Microgrids under Islanded Mode

    Directory of Open Access Journals (Sweden)

    Yao Liu

    2016-08-01

    Full Text Available The increasing penetration of renewable generators can be a significant challenge due to the fluctuation of their power generation. Energy storage (ES units are one solution to improve power supply quality and guarantee system stability. In this paper, a hybrid microgrid is built based on photovoltaic (PV generator and ES; and coordinated control is proposed and developed to achieve power management in a decentralized manner. This control scheme contains three different droop strategies according to characteristics of PV and ES. First, the modified droop control is proposed for PV, which can take full utilization of renewable energy and avoid regulating output active power frequently. Second, to maintain the direct current (DC bus voltage stability, a novel droop control incorporating a constant power band is presented for DC-side ES. Third, a cascade droop control is designed for alternating current (AC-side ES. Thus, the ES lifetime is prolonged. Moreover, interlinking converters (ICs provide a bridge between AC/DC buses in a hybrid microgrid. The power control of IC is enabled when the AC- or DC-side suffer from active power demand shortage. In particular, if the AC microgrid does not satisfy the reactive power demand, IC then acts as a static synchronous compensator (STATCOM. The effectiveness of the proposed strategies is verified by simulations.

  19. Electromechanical systems with transient high power response operating from a resonant ac link

    Science.gov (United States)

    Burrows, Linda M.; Hansen, Irving G.

    1992-01-01

    The combination of an inherently robust asynchronous (induction) electrical machine with the rapid control of energy provided by a high frequency resonant ac link enables the efficient management of higher power levels with greater versatility. This could have a variety of applications from launch vehicles to all-electric automobiles. These types of systems utilize a machine which is operated by independent control of both the voltage and frequency. This is made possible by using an indirect field-oriented control method which allows instantaneous torque control all four operating quadrants. Incorporating the ac link allows the converter in these systems to switch at the zero crossing of every half cycle of the ac waveform. This zero loss switching of the link allows rapid energy variations to be achieved without the usual frequency proportional switching loss. Several field-oriented control systems were developed under contract to NASA.

  20. Advances in high voltage power switching with GTOs

    Energy Technology Data Exchange (ETDEWEB)

    Podlesak, T.F. (US Army Electronic Technology and Devices Lab., Fort Monmouth, NJ (US)); McMurray, J.A. (Vitronics, Eatontown, NJ (US)); Carter, J.L.

    1990-12-01

    The control of high voltage at high power, particularly opening switches, has been difficult in the past. Using gate turnoff thyristors (GTOs) arranged in series enables large currents to be switched at high voltage. A high voltage opening switch has been successfully demonstrated in our laboratory. This switch uses GTOs in series and successfully operates at voltages higher than the rated voltage of the individual devices. It is believed that this is the first time this has been successfully demonstrated, in that GTOs have been operated in series before, but always in a manner as to not exceed the voltage capability of the individual devices. In short, the devices have not worked together, sharing the voltage, but one device has been operated using several backup devices. Of particular interest is how well the individual devices share the voltage applied to them. Equal voltage sharing between devices is absolutely essential, in order to not exceed the voltage rating of any of the devices in the series chain. This is accomplished at high (microsecond) switching speeds. Thus, the system is useful for high frequency applications as well as high power, making for a flexible circuit system element. This paper reports on this demonstration system that is rated at 5 KV and uses 1 KV devices. A larger 24 KV system is under design and will use 4.5 KV devices. In order to design the 24 KV switch, the safe operating area of the large devices must be known thoroughly.

  1. Isolated single-stage high power factor AC/DC converter

    Institute of Scientific and Technical Information of China (English)

    王卫; 贲洪奇; 高国安

    2001-01-01

    The problem of harmonic pollution has brought wide attention with the increase of power customers. The adoption of the technology of active power factor correction (APFC) with advanced high frequency power converter is a more efficient solution to the problem of harmonic pollution. A single-stage isolated high power factor AC/DC converter, which features wide range DC output, high power factor, lower harmonic pollution in input current, and phase-shift PWM full-bridge circuit can achieve soft switching. The principle of the circuit topology and the reasons of voltage surges across the power switch are analyzed. Experiment results illustrate that this circuit has the advantages of high power factor and lower harmonic distortion.

  2. Power flow control of intertied ac microgrids

    DEFF Research Database (Denmark)

    Nutkani, Inam Ullah; Loh, Poh Chiang; Blaabjerg, Frede

    2013-01-01

    of interlinking power converters. Active and reactive power flows of these converters should preferably be managed autonomously without demanding for fast communication links. A scheme that can fulfill the objectives is now proposed, which upon realised, will result in more robustly integrated microgrids...

  3. Influence of Load Modes on Voltage Stability of Receiving Network at DC/AC System

    Directory of Open Access Journals (Sweden)

    Mao Chizu

    2016-01-01

    Full Text Available This paper analyses influence of load modes on DC/AC system. Because of widespread use of HVDC, DC/AC system become more complex than before and the present modes used in dispatch and planning departments are not fit in simulation anymore. So it is necessary to find load modes accurately reflecting characteristics of the system. For the sake of the voltage stability, commutation failure, etc. the practical example of the receiving network in a large DC/AC system in China is simulated with BPA, and the influence of Classical Load Mode (CLM and Synthesis load model (SLM on simulation results is studies. Furthermore, some important parameters of SLM are varied respectively among an interval to analyse how they affect the system. According to this practical examples, the result is closely related to load modes and their parameters, and SLM is more conservative but more reasonable than the present modes. The consequences indicate that at critical states, micro variation in parameters may give rise to change in simulation results radically. Thus, correct mode and parameters are important to enhance simulation accuracy of DC/AC system and researches on how they affect the system make senses.

  4. Interior point algorithm-based power flow optimisation of a combined AC and DC multi-terminal grid

    Directory of Open Access Journals (Sweden)

    Farhan Beg

    2015-01-01

    Full Text Available The high cost of power electronic equipment, lower reliability and poor power handling capacity of the semiconductor devices had stalled the deployment of systems based on DC (multi-terminal direct current system (MTDC networks. The introduction of voltage source converters (VSCs for transmission has renewed the interest in the development of large interconnected grids based on both alternate current (AC and DC transmission networks. Such a grid platform also realises the added advantage of integrating the renewable energy sources into the grid. Thus a grid based on DC MTDC network is a possible solution to improve energy security and check the increasing supply demand gap. An optimal power solution for combined AC and DC grids obtained by the solution of the interior point algorithm is proposed in this study. Multi-terminal HVDC grids lie at the heart of various suggested transmission capacity increases. A significant difference is observed when MTDC grids are solved for power flows in place of conventional AC grids. This study deals with the power flow problem of a combined MTDC and an AC grid. The AC side is modelled with the full power flow equations and the VSCs are modelled using a connecting line, two generators and an AC node. The VSC and the DC losses are also considered. The optimisation focuses on several different goals. Three different scenarios are presented in an arbitrary grid network with ten AC nodes and five converter stations.

  5. Modeling and Design of DC Boost and AC Side Voltage Controllers in Asymmetrical Γ-Source Inverter

    Directory of Open Access Journals (Sweden)

    Seyed Mahyar Mehdizadeh Moghadam

    2014-07-01

    Full Text Available In this paper a control system is proposed to simultaneously control the voltage boost and output voltage of assymetrical Γ-Source Inverters. Dynamic model of the system is used to design the controllers. Voltage boost on assymetrical Γ-Source Inverters is done by voltage control of impedance network capacitor and the regulation of inverter shoot through duty cycle. Since the stability margin of the system is low due to the right half plane zero in its dynamic model, the design of fast control system is impossible therefore a nonlinear feedforward control loop is used to faster the control system performance. Linear control system is used to control the AC-side in synchrony reference frame such that the AC voltage control system regulates the output voltage by means of modulation index regulation. The proposed control system performance is investigated by simulation in MATLAB/Simulink

  6. Robust Frequency and Voltage Stability Control Strategy for Standalone AC/DC Hybrid Microgrid

    Directory of Open Access Journals (Sweden)

    Furqan Asghar

    2017-05-01

    Full Text Available The microgrid (MG concept is attracting considerable attention as a solution to energy deficiencies, especially in remote areas, but the intermittent nature of renewable sources and varying loads cause many control problems and thereby affect the quality of power within a microgrid operating in standalone mode. This might cause large frequency and voltage deviations in the system due to unpredictable output power fluctuations. Furthermore, without any main grid support, it is more complex to control and manage the system. In past, droop control and various other coordination control strategies have been presented to stabilize the microgrid frequency and voltages, but in order to utilize the available resources up to their maximum capacity in a positive way, new and robust control mechanisms are required. In this paper, a standalone microgrid is presented, which integrates renewable energy-based distributed generations and local loads. A fuzzy logic-based intelligent control technique is proposed to maintain the frequency and DC (direct current-link voltage stability for sudden changes in load or generation power. Also from a frequency control perspective, a battery energy storage system (BESS is suggested as a replacement for a synchronous generator to stabilize the nominal system frequency as a synchronous generator is unable to operate at its maximum efficiency while being controlled for stabilization purposes. Likewise, a super capacitor (SC and BESS is used to stabilize DC bus voltages even though maximum possible energy is being extracted from renewable generated sources using maximum power point tracking. This newly proposed control method proves to be effective by reducing transient time, minimizing the frequency deviations, maintaining voltages even though maximum power point tracking is working and preventing generators from exceeding their power ratings during disturbances. However, due to the BESS limited capacity, load switching

  7. Distributed AC power flow method for AC and AC-DC hybrid ...

    African Journals Online (AJOL)

    DR OKE

    Hence the distribution power flow models to be developed were supposed to include both mesh and DG modeling (Sedghi ... Newton-Raphson based power flow methods, namely Newton ... Equation (1) is the mathematical realization of this ...

  8. Living and Working Safely Around High-Voltage Power Lines.

    Energy Technology Data Exchange (ETDEWEB)

    United States. Bonneville Power Administration.

    2001-06-01

    High-voltage transmission lines can be just as safe as the electrical wiring in the homes--or just as dangerous. The crucial factor is ourselves: they must learn to behave safely around them. This booklet is a basic safety guide for those who live and work around power lines. It deals primarily with nuisance shocks due to induced voltages, and with potential electric shock hazards from contact with high-voltage lines. References on possible long-term biological effects of transmission lines are shown. In preparing this booklet, the Bonneville Power Administration has drawn on more than 50 years of experience with high-voltage transmission. BPA operates one of the world`s largest networks of long-distance, high-voltage lines. This system has more than 400 substations and about 15,000 miles of transmission lines, almost 4,400 miles of which are operated at 500,000 volts.

  9. A Survey of High Performance AC Voltage Regulating Technologies%高性能交流电压调节技术的发展概况

    Institute of Scientific and Technical Information of China (English)

    刘汉奎; 顾建军; 徐殿国; 王炎

    2000-01-01

    分析了交流斩波型、单位功率因数变换器 型和串联 型三类开关型交流电压调节装置,并给出了它们的新型拓扑结构。通过对这三种电压调节装 置的对比研究,指出串联型电压调节装置的性能价格比高于其他方式。串并联型电压调节装 置是交流电压调节装置的一个发展方向。%AC chopping voltage regulator,voltage regulator with unity power factor converter and series voltage regulator are analyzed,an d new topologies of each method are shown in this paper.It is pointed out that s eries voltage regulator has higher performance cost ratio,and series and parall el voltage regulator is a trend of AC voltage regulator.

  10. Resistojet control and power for high frequency ac buses

    Science.gov (United States)

    Gruber, Robert P.

    1987-01-01

    Resistojets are operational on many geosynchronous communication satellites which all use dc power buses. Multipropellant resistojets were selected for the Initial Operating Capability (IOC) Space Station which will supply 208 V, 20 kHz power. This paper discusses resistojet heater temperature controllers and passive power regulation methods for ac power systems. A simple passive power regulation method suitable for use with regulated sinusoidal or square wave power was designed and tested using the Space Station multipropellant resistojet. The breadboard delivered 20 kHz power to the resistojet heater. Cold start surge current limiting, a power efficiency of 95 percent, and power regulation of better than 2 percent were demonstrated with a two component, 500 W breadboard power controller having a mass of 0.6 kg.

  11. Temperature Stabilized Characterization of High Voltage Power Supplies

    CERN Document Server

    Krarup, Ole

    2017-01-01

    High precision measurements of the masses of nuclear ions in the ISOLTRAP experiment relies on an MR-ToF. A major source of noise and drift is the instability of the high voltage power supplies employed. Electrical noise and temperature changes can broaden peaks in time-of-flight spectra and shift the position of peaks between runs. In this report we investigate how the noise and drift of high-voltage power supplies can be characterized. Results indicate that analog power supplies generally have better relative stability than digitally controlled ones, and that the high temperature coefficients of all power supplies merit efforts to stabilize them.

  12. Global Transient Stability and Voltage Regulation for Multimachine Power Systems

    DEFF Research Database (Denmark)

    Gordon, Mark; Hill, David J.

    2008-01-01

    This paper addresses simultaneously the major fundamental and difficult issues of nonlinearity, uncertainty, dimensionality and globality to derive performance enhancing power system stability control. The main focus is on simultaneous enhancement of transient stability and voltage regulation...... law is implemented to coordinate transient stabilizer and voltage regulator for each machine. Digital simulation studies show that global control scheme achieves unified transient stability and voltage regulation in the presence of parametric uncertainties and significant sudden changes in the network...... of power systems. This problem arises from the practical concern that both frequency and voltage control are important indices of power system control and operation but they are ascribed to different stages of system operation, i.e. the transient and post transient period respectively. The Direct Feedback...

  13. Voltage Stability in Power system Using STATCOM

    Directory of Open Access Journals (Sweden)

    Mr. D.K. Sharma

    2012-03-01

    Full Text Available the current major restructuring of the electricity market and the advances of new technology add new complexities in the power system applications software, particularly optimization. Minimization of the impact of a transaction on unrelated third party facilities or maximization of the power transfer between utilities needs now to be formulated as new constraints or objective functions. The dispatch and control of generating units, the taps of regulating transformers, mechanically switched capacitors and reactors have been the primary means available for controlling power flows over the years. However, certain applications require frequent operations that result in a rapid wearing out of the switching equipment. The inadequate line flow control may result in overloaded parts of the networks, while other parts are loaded far below their power carrying capacity. Therefore, the demands for flexibility in power flow control are growing continuously. The FACTS relying on thyristors have high speed switching capability that allows for rapid readjustment of line power flows in response to various contingencies. Installation of FACTS devices on key locations in a meshed network changes the effective reactance of the parallel paths and consequently the way that power divides among them. This paper proposes study of various FACTS DEVICES that can be installed. FACTS DEVICES model isincorporated into a Newton-Raphson algorithm to perform load flow analysis. Proposed algorithm is tested on IEEE 30 bus power system for optimal allocation of STATCOM and results are presented.

  14. Voltage Collapse Risk Associated to Under-Voltage Capacitive Compensation in Electric Power System Operation

    Directory of Open Access Journals (Sweden)

    Heraldo S. Barbuy

    2009-01-01

    Full Text Available Problem statement: In the operation of an Electric Power System (EPS, it has been usual to provide reactive power injection to avoid an under-voltage bus condition. In some situations an adequate voltage profile will not be a guarantee against Voltage Collapses (VCs that may cause blackouts as seen in many occurrences around the world. The repeatedly injection of reactive power can turn a bus into a characteristic too much capacitive. Under this condition and in the presence of a considerable percentage of the constant power load type, there will be a high risk of a VC. Any of the indices proposed in the literature as VC Proximity Indicators (VCPIs may alert the operator about the risk. Approach: In order to elucidate the problem stated, simulations were performed using MatLab/SimPowerSystems. It was used a basic example system composed by an infinite-bus feeding, through a large impedance line, a bus load whose power could be increased in ramp manner. It is also included a shunt capacitive compensation at the load bus every time the voltage value reaches 0.9 pu. Therefore, the VC risk increase could be shown by means of graphic results and the indications of some VCPIs sensitivity indices (including the new proposed index. Results: The graphics obtained in this study is a contribution to illustrate the voltage collapse risk problem when dealing with adjustments of voltage profile to meet the system requirements. Also, a VCPI sensitivity indicator using apparent load power was tested. The results have shown that all VCPI responses are very similar for a given case and electric system. Conclusion/Recommendations: Any VCPI information can help in the decision stage between either more reactive power injection or load shedding. A routine can also be developed for a supervisory program in order to alert the operator about VC risks.

  15. Introducing AC Inductive Reactance with a Power Tool

    Science.gov (United States)

    Bryant, Wesley; Baker, Blane

    2016-01-01

    The concept of reactance in AC electrical circuits is often non-intuitive and difficult for students to grasp. In order to address this lack of conceptual understanding, classroom exercises compare the predicted resistance of a power tool, based on electrical specifications, to measured resistance. Once students discover that measured resistance…

  16. Improved Power Control Using Optimal Adjustable Coefficients for Three-Phase Photovoltaic Inverter under Unbalanced Grid Voltage

    Science.gov (United States)

    Wang, Qianggang; Zhou, Niancheng; Lou, Xiaoxuan; Chen, Xu

    2014-01-01

    Unbalanced grid faults will lead to several drawbacks in the output power quality of photovoltaic generation (PV) converters, such as power fluctuation, current amplitude swell, and a large quantity of harmonics. The aim of this paper is to propose a flexible AC current generation method by selecting coefficients to overcome these problems in an optimal way. Three coefficients are brought in to tune the output current reference within the required limits of the power quality (the current harmonic distortion, the AC current peak, the power fluctuation, and the DC voltage fluctuation). Through the optimization algorithm, the coefficients can be determined aiming to generate the minimum integrated amplitudes of the active and reactive power references with the constraints of the inverter current and DC voltage fluctuation. Dead-beat controller is utilized to track the optimal current reference in a short period. The method has been verified in PSCAD/EMTDC software. PMID:25243215

  17. Improved Power Control Using Optimal Adjustable Coefficients for Three-Phase Photovoltaic Inverter under Unbalanced Grid Voltage

    Directory of Open Access Journals (Sweden)

    Qianggang Wang

    2014-01-01

    Full Text Available Unbalanced grid faults will lead to several drawbacks in the output power quality of photovoltaic generation (PV converters, such as power fluctuation, current amplitude swell, and a large quantity of harmonics. The aim of this paper is to propose a flexible AC current generation method by selecting coefficients to overcome these problems in an optimal way. Three coefficients are brought in to tune the output current reference within the required limits of the power quality (the current harmonic distortion, the AC current peak, the power fluctuation, and the DC voltage fluctuation. Through the optimization algorithm, the coefficients can be determined aiming to generate the minimum integrated amplitudes of the active and reactive power references with the constraints of the inverter current and DC voltage fluctuation. Dead-beat controller is utilized to track the optimal current reference in a short period. The method has been verified in PSCAD/EMTDC software.

  18. Improved power control using optimal adjustable coefficients for three-phase photovoltaic inverter under unbalanced grid voltage.

    Science.gov (United States)

    Wang, Qianggang; Zhou, Niancheng; Lou, Xiaoxuan; Chen, Xu

    2014-01-01

    Unbalanced grid faults will lead to several drawbacks in the output power quality of photovoltaic generation (PV) converters, such as power fluctuation, current amplitude swell, and a large quantity of harmonics. The aim of this paper is to propose a flexible AC current generation method by selecting coefficients to overcome these problems in an optimal way. Three coefficients are brought in to tune the output current reference within the required limits of the power quality (the current harmonic distortion, the AC current peak, the power fluctuation, and the DC voltage fluctuation). Through the optimization algorithm, the coefficients can be determined aiming to generate the minimum integrated amplitudes of the active and reactive power references with the constraints of the inverter current and DC voltage fluctuation. Dead-beat controller is utilized to track the optimal current reference in a short period. The method has been verified in PSCAD/EMTDC software.

  19. Total loss of AC power analysis for EPR reactor

    Energy Technology Data Exchange (ETDEWEB)

    Darnowski, Piotr, E-mail: piotr.darnowski@itc.pw.edu.pl [Warsaw University of Technology, Institute of Heat Engineering, Nowowiejska 21/25, 00-665 Warsaw (Poland); Skrzypek, Eleonora, E-mail: eleonora.skrzypek@ncbj.gov.pl [Warsaw University of Technology, Institute of Heat Engineering, Nowowiejska 21/25, 00-665 Warsaw (Poland); National Centre for Nuclear Research (NCBJ), A. Sołtana 7, 05-400 Otwock-Świerk (Poland); Mazgaj, Piotr, E-mail: piotr.mazgaj@itc.pw.edu.pl [Warsaw University of Technology, Institute of Heat Engineering, Nowowiejska 21/25, 00-665 Warsaw (Poland); Świrski, Konrad [Warsaw University of Technology, Institute of Heat Engineering, Nowowiejska 21/25, 00-665 Warsaw (Poland); Gandrille, Pascal [AREVA NP SAS, Tour AREVA, 1 place Jean Millier, 92084 Paris La Défense (France)

    2015-08-15

    Highlights: • Total loss of AC power (Station Blackout) was simulated for the EPR reactor model. • In-vessel phase of the accident is under consideration. • Comparison of MELCOR and MAAP results is presented. • MELCOR and MAAP results are comparable. - Abstract: In this paper the results of severe accident simulations for the EPR reactor in the case of loss of offsite power combined with total failure of all diesel generators (total loss of AC power) are presented. Calculations were performed with MELCOR 2.1 computer code for in-vessel phase of the accident. In this scenario, the unavailability of all offsite and onsite power sources and the lack of cooling leads directly to core degradation, material relocation to the lower plenum and rupture of the reactor pressure vessel. MELCOR results were compared qualitatively and quantitatively with MAAP4 code results and show a good agreement.

  20. Photovoltaic Inverter Controllers Seeking AC Optimal Power Flow Solutions

    Energy Technology Data Exchange (ETDEWEB)

    Dall' Anese, Emiliano; Dhople, Sairaj V.; Giannakis, Georgios B.

    2016-07-01

    This paper considers future distribution networks featuring inverter-interfaced photovoltaic (PV) systems, and addresses the synthesis of feedback controllers that seek real- and reactive-power inverter setpoints corresponding to AC optimal power flow (OPF) solutions. The objective is to bridge the temporal gap between long-term system optimization and real-time inverter control, and enable seamless PV-owner participation without compromising system efficiency and stability. The design of the controllers is grounded on a dual ..epsilon..-subgradient method, while semidefinite programming relaxations are advocated to bypass the non-convexity of AC OPF formulations. Global convergence of inverter output powers is analytically established for diminishing stepsize rules for cases where: i) computational limits dictate asynchronous updates of the controller signals, and ii) inverter reference inputs may be updated at a faster rate than the power-output settling time.

  1. Low-power low-voltage superior-order curvature corrected voltage reference

    Science.gov (United States)

    Popa, Cosmin

    2010-06-01

    A complementary metal oxide semiconductor (CMOS) voltage reference with a logarithmic curvature-correction will be presented. The first-order compensation is realised using an original offset voltage follower (OVF) block as a proportional to absolute temperature (PTAT) voltage generator, with the advantages of reducing the silicon area and of increasing accuracy by replacing matched resistors with matched transistors. The new logarithmic curvature-correction technique will be implemented using an asymmetric differential amplifier (ADA) block for compensating the logarithmic temperature dependent term from the first-order compensated voltage reference. In order to increase the circuit accuracy, an original temperature-dependent current generator will be designed for computing the exact type of the implemented curvature-correction. The relatively small complexity of the current squarer allows an important increasing of the circuit accuracy that could be achieved by increasing the current generator complexity. As a result of operating most of the MOS transistors in weak inversion, the original proposed voltage reference could be valuable for low-power applications. The circuit is implemented in 0.35 μm CMOS technology and consumes only 60μA for t = 25°C, being supplied at the minimal supply voltage V DD = 1.75V. The temperature coefficient of the reference voltage is 8.7 ppm/°C, while the line sensitivity is 0.75 mV/V for a supply voltage between 1.75 V and 7 V.

  2. Power factor correction, controlling voltage distortion

    Directory of Open Access Journals (Sweden)

    A. Ceclan

    2008-05-01

    Full Text Available This paper presents, an approach fordetermining optimal sizes of single-tuned passiveharmonic filters among existent capacitor busses ina power system. The proposed method uses EdsaHarmonics Analysis and the obtained results arepresented in detail.

  3. A Novel Active Bouncer System for Klystron Modulators with Constant AC Power Consumption

    CERN Document Server

    Cabaleiro Magallanes, F; Viarouge, P; Cros, J; De Almeida Martins, C

    2014-01-01

    This paper presents the principles and design methodologies of a novel active bouncer system, to be implemented in a transformer-based klystron modulator, which is able to meet two different objectives: 1. Regulate the output pulse voltage flattop, and 2. Attenuate the power fluctuation withdrawn from the AC network. This solution allows the utilization of a standard constant voltage / constant current power supply as a capacitor charger. The solution consists of a 4-quadrant switching converter placed in series with the main capacitor bank (forming a unique element in parallel with the capacitor charger), controlled with specific feed-back loops to achieve the two objectives. The complete design method, including a numerical optimization, of the whole system, is presented in the paper. Analyses of the compromises between the active bouncer specifications and the other modulator sub-components design is presented as well.

  4. Surface Partial Discharge Characteristics of Oil-paper Insulation Under Combined AC-DC Voltage

    Institute of Scientific and Technical Information of China (English)

    SHA Yanchao; ZHOU Yuanxiang; NIE Dexin; WU Zhirong; DENG Jiangang; LU Licheng

    2013-01-01

    The valve side windings of converter transformers bear AC,DC,impulse,and reversal-polarity voltages during operation,which could result in serious insulation problems of the equipment.By performing experiments with surface discharge model of oil-paper insulation at 80 ℃ under combined AC-DC voltage for 200 h,we studied the spectrums and statistical parameters of partial discharges at different discharge stages.Furthermore,some fingerprint parameters were calculated in order to estimate the development situation of partial discharge,while the characteristic gases dissolved in the transformer oil were measured by gas chromatography.The surface discharges in the experiments were observed using a high speed camera,and a full discharge process could be marked off into four stages as follows.①The elementary stage.When a partial discharge occurs near electrodes,electrical charges are injected into the region near electrodes and causing bubble generation.②Due to their high resistivity and low dielectric constant,the bubbles would bare the major part of the voltage applied to samples.Therefore,discharge happens inside the small bubbles,and it emits a lot of light.③Micmmolecules of gas are produced in discharge,and further ionization in the transformer oil takes place simultaneously when high-energy electrons collide with oil molecules.④The carrier charge moves forward to electrodes driven by the applied electric field,till they neutralize with the charge from electrodes,and hence discharge channels are formed subsequently.

  5. Low Power/Low Voltage Interface Circuitry for Capacitive Sensors

    DEFF Research Database (Denmark)

    Furst, Claus Efdmann

    This thesis focuses mainly on low power/low voltage interface circuits, implemented in CMOS, for capacitive sensors. A brief discussion of demands and possibilities for analog signal processing in the future is presented. Techniques for low power design is presented. This is done by analyzing power...... consumption of different amplifier topologies. Next, low power features of different amplifier types are analyzed on transistor level. A brief comparison of SI circuits for low power applications vs. SC circuits is presented. Methodologies for low voltage design is presented. This is followed by a collection...... power consumption. It is shown that the Sigma-Delta modulator is advantageous when embedded in a feedback loop with a mechanical sensor. Here a micro mechanical capacitive microphone. Feedback and detection circuitry for a capacitive microphone is presented. Practical implementations of low power...

  6. Application of FACTS devices to the 330 kV Nigerian system for voltage and power control

    Energy Technology Data Exchange (ETDEWEB)

    Komolafe, O.A. [Obafemi Awolowo Univ., Ile-Ife (Nigeria). Dept. of Electronic and Electrical Engineering; Adepoju, G. [Ladoke Akintola Univ. of Technology, Ogbomoso (Nigeria). Dept. of Electronic and Electrical Engineering; Garcia-Valle, R. [Technical Univ. of Denmark, Lyngby (Denmark). CET-Elektro

    2008-07-01

    Various flexible AC transmission system (FACTS) devices were investigated in this study. A static VAR compensator (SVC), static synchronous compensator (STATCOM) and a unified power flow controller (UPFC) were simulated in order to determine their voltage regulation and power flow control ability for a 330 kV transmission system in Nigeria. The FACTS models were tested on standard power networks and then modelled with a Newton-Raphson algorithm as part of a power flow analysis. The study identified potential locations for the devices in the Nigerian transmission network. Four case studies were considered in order to determine optimal configurations for the devices within the network. The study showed that the SVC and STATCOM devices regulate voltage buses without violating susceptance or voltage limits. The UPFC can control active power flow through transmission lines connecting the northern region of the country to areas with a high demand for power supply. 10 refs., 7 tabs., 5 figs.

  7. Intense neutron source: high-voltage power supply specifications

    Energy Technology Data Exchange (ETDEWEB)

    Riedel, A.A.

    1980-08-01

    This report explains the need for and sets forth the electrical, mechanical and safety specifications for a high-voltage power supply to be used with the intense neutron source. It contains sufficient information for a supplier to bid on such a power supply.

  8. Conventional P-ω/Q-V Droop Control in Highly Resistive Line of Low-Voltage Converter-Based AC Microgrid

    Directory of Open Access Journals (Sweden)

    Xiaochao Hou

    2016-11-01

    Full Text Available In low-voltage converter-based alternating current (AC microgrids with resistive distribution lines, the P-V droop with Q-f boost (VPD/FQB is the most common method for load sharing. However, it cannot achieve the active power sharing proportionally. To overcome this drawback, the conventional P-ω/Q-V droop control is adopted in the low-voltage AC microgrid. As a result, the active power sharing among the distributed generators (DGs is easily obtained without communication. More importantly, this study clears up the previous misunderstanding that conventional P-ω/Q-V droop control is only applicable to microgrids with highly inductive lines, and lays a foundation for the application of conventional droop control under different line impedances. Moreover, in order to guarantee the accurate reactive power sharing, a guide for designing Q-V droop gains is given, and virtual resistance is adopted to shape the desired output impedance. Finally, the effects of power sharing and transient response are verified through simulations and experiments in converter-based AC Microgrid.

  9. Adapting AC Lines to DC Grids for Large-Scale Renewable Power Transmission

    Directory of Open Access Journals (Sweden)

    D. Marene Larruskain

    2014-10-01

    Full Text Available All over the world, governments of different countries are nowadays promoting the use of clean energies in order to achieve sustainable energy systems. In this scenario, since the installed capacity is continuously increasing, renewable sources can play an important role. Notwithstanding that, some important problems may appear when connecting these sources to the grid, being the overload of distribution lines one of the most relevant. In fact, renewable generation is usually connected to the nearest AC grid, although this HV system may not have been designed considering distributed generation. In the particular case of large wind farms, the electrical grid has to transmit all the power generated by wind energy and, as a consequence, the AC system may get overloaded. It is therefore necessary to determine the impact of wind power transmission so that appropriate measures can be taken. Not only are these measures influenced by the amount of power transmitted, but also by the quality of the transmitted power, due to the output voltage fluctuation caused by the highly variable nature of wind. When designing a power grid, although AC systems are usually the most economical solution because of its highly proven technology, HVDC may arise in some cases (e.g. offshore wind farms as an interesting alternative, offering some added values such as lower losses and better controllability. This way, HVDC technology can solve most of the aforementioned problems and has a good potential for future use. Additionally, the fast development of power electronics based on new and powerful semiconductor devices allow the spread of innovative technologies, such as VSC-HVDC, which can be applied to create DC grids. This paper focuses on the main aspects involved in adapting the existing overhead AC lines to DC grids, with the objective of improving the transmission of distributed renewable energy to the centers of consumption.

  10. Reliability and Characterization of High Voltage Power Capacitors

    Science.gov (United States)

    2014-03-01

    ix LIST OF FIGURES Figure 1.   System level overview of IPC EVCS (from [3]). ..............................................2   Figure 2...permittivity EVCS electric vehicle charging system GPIB general-purpose interface bus GW giga-watt HVST high voltage stress test IV current voltage...Power Converter (IPC). This converter is being used for the Electric Vehicle Charging Station ( EVCS ), currently being investigated and installed in

  11. Optimal placement of unified power flow controllers to improve dynamic voltage stability using power system variable based voltage stability indices.

    Science.gov (United States)

    Albatsh, Fadi M; Ahmad, Shameem; Mekhilef, Saad; Mokhlis, Hazlie; Hassan, M A

    2015-01-01

    This study examines a new approach to selecting the locations of unified power flow controllers (UPFCs) in power system networks based on a dynamic analysis of voltage stability. Power system voltage stability indices (VSIs) including the line stability index (LQP), the voltage collapse proximity indicator (VCPI), and the line stability index (Lmn) are employed to identify the most suitable locations in the system for UPFCs. In this study, the locations of the UPFCs are identified by dynamically varying the loads across all of the load buses to represent actual power system conditions. Simulations were conducted in a power system computer-aided design (PSCAD) software using the IEEE 14-bus and 39- bus benchmark power system models. The simulation results demonstrate the effectiveness of the proposed method. When the UPFCs are placed in the locations obtained with the new approach, the voltage stability improves. A comparison of the steady-state VSIs resulting from the UPFCs placed in the locations obtained with the new approach and with particle swarm optimization (PSO) and differential evolution (DE), which are static methods, is presented. In all cases, the UPFC locations given by the proposed approach result in better voltage stability than those obtained with the other approaches.

  12. Optimal placement of unified power flow controllers to improve dynamic voltage stability using power system variable based voltage stability indices.

    Directory of Open Access Journals (Sweden)

    Fadi M Albatsh

    Full Text Available This study examines a new approach to selecting the locations of unified power flow controllers (UPFCs in power system networks based on a dynamic analysis of voltage stability. Power system voltage stability indices (VSIs including the line stability index (LQP, the voltage collapse proximity indicator (VCPI, and the line stability index (Lmn are employed to identify the most suitable locations in the system for UPFCs. In this study, the locations of the UPFCs are identified by dynamically varying the loads across all of the load buses to represent actual power system conditions. Simulations were conducted in a power system computer-aided design (PSCAD software using the IEEE 14-bus and 39- bus benchmark power system models. The simulation results demonstrate the effectiveness of the proposed method. When the UPFCs are placed in the locations obtained with the new approach, the voltage stability improves. A comparison of the steady-state VSIs resulting from the UPFCs placed in the locations obtained with the new approach and with particle swarm optimization (PSO and differential evolution (DE, which are static methods, is presented. In all cases, the UPFC locations given by the proposed approach result in better voltage stability than those obtained with the other approaches.

  13. Optimal Placement of Unified Power Flow Controllers to Improve Dynamic Voltage Stability Using Power System Variable Based Voltage Stability Indices

    Science.gov (United States)

    Albatsh, Fadi M.; Ahmad, Shameem; Mekhilef, Saad; Mokhlis, Hazlie; Hassan, M. A.

    2015-01-01

    This study examines a new approach to selecting the locations of unified power flow controllers (UPFCs) in power system networks based on a dynamic analysis of voltage stability. Power system voltage stability indices (VSIs) including the line stability index (LQP), the voltage collapse proximity indicator (VCPI), and the line stability index (Lmn) are employed to identify the most suitable locations in the system for UPFCs. In this study, the locations of the UPFCs are identified by dynamically varying the loads across all of the load buses to represent actual power system conditions. Simulations were conducted in a power system computer-aided design (PSCAD) software using the IEEE 14-bus and 39- bus benchmark power system models. The simulation results demonstrate the effectiveness of the proposed method. When the UPFCs are placed in the locations obtained with the new approach, the voltage stability improves. A comparison of the steady-state VSIs resulting from the UPFCs placed in the locations obtained with the new approach and with particle swarm optimization (PSO) and differential evolution (DE), which are static methods, is presented. In all cases, the UPFC locations given by the proposed approach result in better voltage stability than those obtained with the other approaches. PMID:25874560

  14. Three-Phase AC Optimal Power Flow Based Distribution Locational Marginal Price: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Rui; Zhang, Yingchen

    2017-05-17

    Designing market mechanisms for electricity distribution systems has been a hot topic due to the increased presence of smart loads and distributed energy resources (DERs) in distribution systems. The distribution locational marginal pricing (DLMP) methodology is one of the real-time pricing methods to enable such market mechanisms and provide economic incentives to active market participants. Determining the DLMP is challenging due to high power losses, the voltage volatility, and the phase imbalance in distribution systems. Existing DC Optimal Power Flow (OPF) approaches are unable to model power losses and the reactive power, while single-phase AC OPF methods cannot capture the phase imbalance. To address these challenges, in this paper, a three-phase AC OPF based approach is developed to define and calculate DLMP accurately. The DLMP is modeled as the marginal cost to serve an incremental unit of demand at a specific phase at a certain bus, and is calculated using the Lagrange multipliers in the three-phase AC OPF formulation. Extensive case studies have been conducted to understand the impact of system losses and the phase imbalance on DLMPs as well as the potential benefits of flexible resources.

  15. Statistical evaluation of telephone noise interference caused by AC power line harmonic currents

    Energy Technology Data Exchange (ETDEWEB)

    Kuussaari, M. (Imatran Voima Oy, Vantaa (Finland))

    1993-04-01

    A statistical approach is applied for the evaluation of the limits for harmonic currents in AC power lines, the goal being to prevent excessive telephone noise interference voltages in subscriber cables in rural areas. The analysis is based on Monte-Carlo simulation which takes into account the effect of the experiental probability distributions of the relevant parameters. In the Finnish conditions, the properties of communication cables permit equivalent disturbing phase currents of 8 to 10 A. The digital exchanges permit approximately the same currents. Some new telephone types that have a low balance may make it necessary to limit the currents to a level that is somewhat lower.

  16. 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.

  17. Single-phase dynamic voltage restorer based on a new chopper AC/DC/AC conversion%一种新型斩波 AC/DC/AC 变换的单相 DVR

    Institute of Scientific and Technical Information of China (English)

    巫付专; 侯婷婷; 韩梁; 冯占伟

    2015-01-01

    针对输入侧采用不可控整流AC/DC/AC结构的单相动态电压恢复器( DVR )输入侧功率因数低,谐波含量高等问题,提出了一种基于PWM斩波变换器的动态电压恢复器来补偿负载两端电压的跌落。该新型拓扑结构采用PWM斩波控制节省了直流侧电容,简化了滤波器设计,使输入侧线路中谐波含量降低,同时达到单位功率因数;电压检测采用单相信号构造成两相信号,利用瞬时无功理论对信号进行检测与处理,实时性高;搭建MATLAB/Simulink仿真和系统实验平台,验证其合理性和可行性。%In view of such problems as the low input side power factor of the single-phase dynamic voltage restorer ( DVR) with the structure of uncontrolled rectifier AC/DC/AC and high harmonic content , this paper proposed a DVR based on the PWM chopper to compensate for the voltage drop at the two load ends .The new topology , which a-dopted the PWM chopper control , saved the DC capacitor and simplified the filter design so that the harmonic content in the input-side circuit was reduced and the input side achieved the unit power factor .Single-phase signals were con-structed into two-phase signals to detect voltage and the instantaneous reactive power theory was used to detect and process the signals , which attained high real time .Finally, a MATLAB/Simulink simulation and experimental plat-form was constructed to verify the rationality and feasibility of the new structure .

  18. The influence of microwave irradiation power on current voltage characteristics of intrinsic Josephson junctions

    Science.gov (United States)

    Shukrinov, Yu M.; Mans, M.; Scherbel, J.; Seidel, P.

    2007-02-01

    The current-voltage characteristics of a micrometre bridge of intrinsic Josephson junctions under microwave irradiation are studied. The collective switching of the group of four junctions splits up as the AC signal amplitude is gradually increased. The switching current of the remaining group of junctions is increased with increasing radiation power. We consider that microwave irradiation injects an additional quasiparticle current into the Josephson junction array. We use ideas of breakdown of quasineutrality and quasiparticle charge imbalance in the superconducting layers and explain the experimental results by the competition between the 'current effect' and the effect of suppression of the switching current by irradiation.

  19. The influence of microwave irradiation power on current-voltage characteristics of intrinsic Josephson junctions

    Energy Technology Data Exchange (ETDEWEB)

    Shukrinov, Yu M [BLTP, JINR, Dubna, Moscow Region, 141980 (Russian Federation); Mans, M [Institut fur Festkoerperphysik, Friedrich-Schiller-Universitaet Jena, D-07743 Jena (Germany); Scherbel, J [Institut fur Festkoerperphysik, Friedrich-Schiller-Universitaet Jena, D-07743 Jena (Germany); Seidel, P [Institut fur Festkoerperphysik, Friedrich-Schiller-Universitaet Jena, D-07743 Jena (Germany)

    2007-02-15

    The current-voltage characteristics of a micrometre bridge of intrinsic Josephson junctions under microwave irradiation are studied. The collective switching of the group of four junctions splits up as the AC signal amplitude is gradually increased. The switching current of the remaining group of junctions is increased with increasing radiation power. We consider that microwave irradiation injects an additional quasiparticle current into the Josephson junction array. We use ideas of breakdown of quasineutrality and quasiparticle charge imbalance in the superconducting layers and explain the experimental results by the competition between the 'current effect' and the effect of suppression of the switching current by irradiation.

  20. Modelling and Simulation of the SVC for Power System Flow Studies: Electrical Network in voltage drop

    OpenAIRE

    Narimen Aouzellag LAHAÇANI; Boubekeur MENDIL

    2008-01-01

    The goal of any Flexible AC Transmission Systems (FACTS) devices study is to measure their impact on the state of the electrical networks into which they are introduced. Their principal function is to improve the static and dynamic properties of the electrical networks and that by increasing the margins of static and dynamic stability and to allow the power transit to the thermal limits of the lines.To study this impact, it is necessary to establish the state of the network (bus voltages and ...

  1. A Hybrid Optimization Method for Reactive Power and Voltage Control Considering Power Loss Minimization

    DEFF Research Database (Denmark)

    Liu, Chengxi; Qin, Nan; Bak, Claus Leth;

    2015-01-01

    This paper proposes a hybrid optimization method to optimally control the voltage and reactive power with minimum power loss in transmission grid. This approach is used for the Danish automatic voltage control (AVC) system which is typically a non-linear non-convex problem mixed with both continu...

  2. Modeling and Analysis of Harmonic Stability in an AC Power-Electronics-Based Power System

    DEFF Research Database (Denmark)

    Wang, Xiongfei; Blaabjerg, Frede; Wu, Weimin

    2014-01-01

    This paper addresses the harmonic stability caused by the interactions among the wideband control of power converters and passive components in an AC power-electronicsbased power system. The impedance-based analytical approach is employed and expanded to a meshed and balanced threephase network...

  3. Modeling and analysis of harmonic resonance in a power electronics based AC power system

    DEFF Research Database (Denmark)

    Wang, Xiongfei; Blaabjerg, Frede; Chen, Zhe

    2013-01-01

    The dynamic interactions among the interconnected power converters may bring in harmonic resonance in a power electronics based power system. This paper addresses this issue in a power system dominated by multiple current- and voltage-controlled inverters with LCL- and LC-filters. The impedance-b...

  4. 21 CFR 880.5100 - AC-powered adjustable hospital bed.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false AC-powered adjustable hospital bed. 880.5100... (CONTINUED) MEDICAL DEVICES GENERAL HOSPITAL AND PERSONAL USE DEVICES General Hospital and Personal Use Therapeutic Devices § 880.5100 AC-powered adjustable hospital bed. (a) Identification. An AC-powered...

  5. A Series-LC-Filtered Active Damper with Grid Disturbance Rejection for AC Power-Electronics-Based Power Systems

    DEFF Research Database (Denmark)

    Wang, Xiongfei; Pang, Ying; Loh, Poh Chiang;

    2015-01-01

    damper. Unlike an active power filter for mitigating low-frequency harmonics, the proposed damper dampens resonances at higher frequencies, whose values are dependent on interactions among multiple grid-connected converters and reactive elements of the system. Its control requirements are, therefore......-order resonant controller, in addition to the second-order resonant controller used for resonance damping. Experimental results obtained have confirmed the effectiveness of these controllers, and hence, the feasibility of the active damper.......This letter proposes an active damper with a series LC filter for suppressing resonances in an ac power-electronics-based power system. The added series filter capacitor helps to withstand most of the system voltage, hence, allowing a lower rated converter to be used for implementing the active...

  6. Final design of the Korean AC/DC converters for the ITER coil power supply system

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Jong-Seok, E-mail: jsoh@nfri.re.kr [ITER Korea, National Fusion Research Institute, Daejeon 305-806 (Korea, Republic of); Choi, Jungwan; Suh, Jae-Hak; Choi, Jihyun [ITER Korea, National Fusion Research Institute, Daejeon 305-806 (Korea, Republic of); Lee, Lacksang; Kim, Changwoo; Park, Hyungjin; Jo, Seongman; Lee, Seungyun; Hwang, Kwangcheol; Liu, Hyoyol [Dawonsys Corp., Siheung 429-450 (Korea, Republic of); Hong, Ki-Don; Sim, Dong-Joon; Lee, Jang-Soo [Hyosung Corp., Gongdeok-Dong, Seoul 121-720 (Korea, Republic of); Lee, Eui-Jae; Kwon, Yang-Hae; Lee, Dae-Yeol; Ko, Ki-Won; Kim, Jong-Min [Mobiis Corp., Yangjae-dong, Seoul 137-888 (Korea, Republic of); Song, Inho [ITER Organization, Route de Vinon sur Verdon, CS 90 046, 13067 St. Paul Lez Durance Cedex (France); and others

    2015-10-15

    The final design of the ITER TF, CS, CC and VS AC/DC converters has been completed to implement ITER requirements following the detailed design and refinements of the preliminary design. The number of parallel thyristors and the rating of fuses are coordinated to keep those devices within the explosion limit even under most severe fault conditions. The impedance of the converter transformer has been optimized taking into account the energization inrush current, short circuit current, reactive power consumption and the available DC voltage. To ensure system integrity, AC/DC converters are mechanically divided into transformers, AC busbars, 6-pulse bridges, DC interconnecting busbars and DC reactors, and then all subsystems are decoupled by flexible links. To provide stable real time network communication down to the converters, a one GbE link is deployed between master controllers and local controllers. IEEE 1588 is implemented to the embedded controllers for precision time synchronization. This paper describes the detailed solutions implemented in the final design for the ITER AC/DC converters with R&D results of converter prototypes.

  7. Power Restoration in Medium Voltage Network Using Multiagent System

    Directory of Open Access Journals (Sweden)

    Miroslav Kovac

    2013-01-01

    Full Text Available The article describes a novel approach to a power restoration in medium voltage power distribution network. It focuses primary at searching of a new network configuration enabling to minimalize the size of faulted area and to restore the power for the highest possible number of loads. It describes characteristic features of medium voltage power distribution network and discusses the implementation of the presented approach in existing networks. A software tool, developed by the authors, including physical simulation of model network and its autonomous control system is described. An example of fault situation in a virtual distribution network is presented. Afterwards, the solution of restoration problem by proposed multiagent system is simulated using the software tool described in the paper.

  8. A Multi-channel AC Power Supply Controller

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A multi-channel AC power Supply controler developed recently by us was introdueed briefty in this paper.This controller is a computer controlled multi-electronic-switch device.The controller contains 16 independent channels in a standard box(440W×405D×125H mm).There is an electronic switch in each channel,the rated load power is≤1 kW.The main function of the controller is to set the state of electronic switch(ON/OFF)

  9. Decentralized Adaptive Overcurrent Protection for Medium Voltage Maritime Power Systems

    DEFF Research Database (Denmark)

    Ciontea, Catalin-Iosif; Bak, Claus Leth; Blaabjerg, Frede;

    2016-01-01

    control unit. The new adaptive protection method is based on communication between the overcurrent relays and the equipment that could affect the protection system, such as circuit breakers and generators. Using PSCAD, the proposed method is implemented in a test medium voltage maritime power system...

  10. Plasma antennas driven by 5–20 kHz AC power supply

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Jiansen, E-mail: 67093058@qq.com; Chen, Yuli; Sun, Yang; Wu, Huafeng; Liu, Yue; Yuan, Qiumeng [Merchant Marine College, Shanghai Maritime University, Shanghai, 201306 (China)

    2015-12-15

    The experiments described in this work were performed with the aim of introducing a new plasma antenna that was excited by a 5–20 kHz alternating current (AC) power supply, where the antenna was transformed into a U-shape. The results show that the impedance, voltage standing-wave ratio (VSWR), radiation pattern and gain characteristics of the antenna can be controlled rapidly by varying not only the discharge power, but also by varying the discharge frequency in the range from 5 to 20 kHz. When the discharge frequency is adjusted from 10 to 12 kHz, the gain is higher within a relatively broad frequency band and the switch-on time is less than 1 ms when the discharge power is less than 5 W, meaning that the plasma antenna can be turned on and off rapidly.

  11. Modularized Three-Phase Semiconductor Transformer with Bidirectional Power Flow for Medium Voltage Application

    Directory of Open Access Journals (Sweden)

    Do-Hyun Kim

    2016-08-01

    Full Text Available This paper describes a prototype of modularized three-phase semiconductor transformer that was developed in the lab for feasibility study. The developed prototype is composed of three units of single-phase semiconductor transformer coupled in Y-connection. Each single-phase unit has multiple units of high-voltage high-frequency resonant AC–DC converter, a low-voltage hybrid-switching DC–DC converter, and a low-voltage hybrid-switching DC–AC inverter. Also, each single-phase unit has two digital signal processor (DSP boards to control converter operation and to acquire monitoring data. The monitoring system was developed based on LabView by using controller area network (CAN communication between the DSP board and the personal computer (PC. Through diverse experimental analyses it was verified that the prototype operates with proper performance under normal and sag conditions. The developed prototype confirms the possibility of fabricating a commercial high-voltage high-power semiconductor transformer by increasing the number of series-connected converter modules in high-voltage side and improving the system efficiency with a new switching device such as an SiC device.

  12. Modelling of long High Voltage AC Cables in the Transmission System

    DEFF Research Database (Denmark)

    Gudmundsdottir, Unnur Stella

    , EMTDC/PSCAD is provided. A typical HV AC underground power cable is formed by 4 main layers, namely; Conductor-Insulation-Screen-Insulation. In addition to these main layers, the cable also has semiconductive screens, swelling tapes and metal foil. For high frequency modelling in EMT-based software...... and field measurement results. This is because of intersheath mode reflecting from the crossbonding points. The second main part of the work deals with improving the cable model based on the findings from analysis of the field measurements. The existing EMT-based models have the configuration for cables...

  13. Design of A Low Power Low Voltage CMOS Opamp

    CERN Document Server

    Baruah, Ratul Kr

    2010-01-01

    In this paper a CMOS operational amplifier is presented which operates at 2V power supply and 1microA input bias current at 0.8 micron technology using non conventional mode of operation of MOS transistors and whose input is depended on bias current. The unique behaviour of the MOS transistors in subthreshold region not only allows a designer to work at low input bias current but also at low voltage. While operating the device at weak inversion results low power dissipation but dynamic range is degraded. Optimum balance between power dissipation and dynamic range results when the MOS transistors are operated at moderate inversion. Power is again minimised by the application of input dependant bias current using feedback loops in the input transistors of the differential pair with two current substractors. In comparison with the reported low power low voltage opamps at 0.8 micron technology, this opamp has very low standby power consumption with a high driving capability and operates at low voltage. The opamp ...

  14. Plasma characteristics of argon glow discharge produced by AC power supply operating at low frequencies

    Energy Technology Data Exchange (ETDEWEB)

    Kongpiboolkid, Watcharapon; Mongkolnavin, Rattachat [Department of Physics, Facuty of Science, Chulalongkorn University, Bangkok (Thailand); Plasma Technology and Nuclear Fusion Research Unit, Chulalongkorn University, Bangkok (Thailand)

    2015-04-24

    Non-thermal properties of Argon glow discharge operating with various operating pressures were measured and presented in this work. The Argon plasma is produced by a parallel conducting electrodes coupling with a high voltage AC power supply. The power supply can generate high AC voltage at various frequencies. The frequencies for the operation are in the range of a few kHz. The system is capable of generating electric field between the two metal electrodes discharge system. The characteristics of plasma produced were measured by optical emission spectroscopy (OES) technique where electron temperature (T{sub e}) and electron number density (n{sub e}) can be determined by line intensity ratio method. The value of electron number density was then determined from the Saha-Eggert equation. Our results show that the electron number density of the discharge obtained is of the order of 10{sup −17} − 10{sup −18} m{sup −3} where the electron temperature is between 1.00−2.00 eV for various operating frequencies used which are in good agreement with similar results published earlier.

  15. High-Voltage, Low-Power BNC Feedthrough Terminator

    Science.gov (United States)

    Bearden, Douglas

    2012-01-01

    This innovation is a high-voltage, lowpower BNC (Bayonet Neill-Concelman) feedthrough that enables the user to terminate an instrumentation cable properly while connected to a high voltage, without the use of a voltage divider. This feedthrough is low power, which will not load the source, and will properly terminate the instrumentation cable to the instrumentation, even if the cable impedance is not constant. The Space Shuttle Program had a requirement to measure voltage transients on the orbiter bus through the Ground Lightning Measurement System (GLMS). This measurement has a bandwidth requirement of 1 MHz. The GLMS voltage measurement is connected to the orbiter through a DC panel. The DC panel is connected to the bus through a nonuniform cable that is approximately 75 ft (approximately equal to 23 m) long. A 15-ft (approximately equal to 5-m), 50-ohm triaxial cable is connected between the DC panel and the digitizer. Based on calculations and simulations, cable resonances and reflections due to mismatched impedances of the cable connecting the orbiter bus and the digitizer causes the output not to reflect accurately what is on the bus. A voltage divider at the DC panel, and terminating the 50-ohm cable properly, would eliminate this issue. Due to implementation issues, an alternative design was needed to terminate the cable properly without the use of a voltage divider. Analysis shows how the cable resonances and reflections due to the mismatched impedances of the cable connecting the orbiter bus and the digitizer causes the output not to reflect accurately what is on the bus. After simulating a dampening circuit located at the digitizer, simulations were performed to show how the cable resonances were dampened and the accuracy was improved significantly. Test cables built to verify simulations were accurate. Since the dampening circuit is low power, it can be packaged in a BNC feedthrough.

  16. A novel full soft-switching resonant power converter for mid-feeder voltage regulation of low voltage distribution network

    OpenAIRE

    Ji, Chao; Watson, Alan James; Clare, Jon C.; Johnson, Christopher Mark

    2016-01-01

    This paper presents a novel resonant based, high power density power electronics converter solution for mid-feeder voltage regulation of a low voltage (LV) distribution network. Owing to the use of high switching frequency operation and a full soft-switching control strategy, the proposed converter is capable of superimposing LV compensation into the feeder voltage, to achieve a significant system effect with a compact system volume and correspondingly smaller absolute power loss.

  17. Soft switching (ZVZCS) high current, low voltage modular power converter (13 kA, 16 V)

    CERN Document Server

    Bordry, Frederick; Thiesen, H

    2001-01-01

    The Large Hadron Collider (LHC) is the next accelerator being constructed at the European Laboratory for Particle Physics (CERN). The superconducting LHC particle accelerator requires high currents (13 kA) and relatively low voltages (16 V) for its magnets. This paper describes the development and the production of a (13 kA, 16 V) power converter. The converter is made with a modular concept with five current sources (3.25 kA, 16 V) in parallel. The 3.25 kA sources are built as plug-in modules: a diode rectifier on the AC mains, a zero voltage zero current switching (ZVZCS) inverter working at 25 k Hz and an output stage. The obtained performance is presented and discussed. (6 refs).

  18. Wide Operational Range Processor Power Delivery Design for Both Super-Threshold Voltage and Near-Threshold Voltage Computing

    Institute of Scientific and Technical Information of China (English)

    Xin He; Gui-Hai Yan; Yin-He Han; Xiao-Wei Li

    2016-01-01

    The load power range of modern processors is greatly enlarged because many advanced power management techniques are employed, such as dynamic voltage frequency scaling, Turbo Boosting, and near-threshold voltage (NTV) technologies. However, because the efficiency of power delivery varies greatly with different load conditions, conventional power delivery designs cannot maintain high efficiency over the entire voltage spectrum, and the gained power saving may be offset by power loss in power delivery. We propose SuperRange, a wide operational range power delivery unit. SuperRange complements the power delivery capability of on-chip voltage regulator and off-chip voltage regulator. On top of SuperRange, we analyze its power conversion characteristics and propose a voltage regulator (VR) aware power management algorithm. Moreover, as more and more cores have been integrated on a singe chip, multiple SuperRange units can serve as basic building blocks to build, in a highly scalable way, more powerful power delivery subsystem with larger power capacity. Experimental results show SuperRange unit offers 1x and 1.3x higher power conversion efficiency (PCE) than other two conventional power delivery schemes at NTV region and exhibits an average 70%PCE over entire operational range. It also exhibits superior resilience to power-constrained systems.

  19. Excimer laser annealing for low-voltage power MOSFET

    Science.gov (United States)

    Chen, Yi; Okada, Tatsuya; Noguchi, Takashi; Mazzamuto, Fulvio; Huet, Karim

    2016-08-01

    Excimer laser annealing of lumped beam was performed to form the P-base junction for high-performance low-voltage-power MOSFET. An equivalent shallow-junction structure for the P-base junction with a uniform impurity distribution is realized by adopting excimer laser annealing (ELA). The impurity distribution in the P-base junction can be controlled precisely by the irradiated pulse energy density and the number of shots of excimer laser. High impurity activation for the shallow junction has been confirmed in the melted phase. The application of the laser annealing technology in the fabrication process of a practical low-voltage trench gate MOSFET was also examined.

  20. Congestion management considering voltage security of power systems

    Energy Technology Data Exchange (ETDEWEB)

    Esmaili, Masoud; Shayanfar, Heidar Ali [Centre of Excellence for Power System Automation and Operation, Iran Univ. of Science and Technology, Tehran (Iran); Amjady, Nima [Dept. of Electrical Engineering, Semnan Univ., Semnan (Iran)

    2009-10-15

    Congestion in a power network is turned up due to system operating limits. To relieve congestion in a deregulated power market, the system operator pays to market participants, GENCOs and DISCOs, to alter their active powers considering their bids. After performing congestion management, the network may be operated with a low security level because of hitting some flows their upper limit and some voltages their lower limit. In this paper, a novel congestion management method based on the voltage stability margin sensitivities is introduced. Using the proposed method, the system operator so alleviates the congestion that the network can more retain its security. The proposed method not only makes the system more secure after congestion management than other methods already presented for this purpose but also its cost of providing security is lower than the earlier methods. Test results of the proposed method along with the earlier ones on the New-England test system elaborate the efficiency of the proposed method from the viewpoint of providing a better voltage stability margin and voltage profile as well as a lower security cost. (author)

  1. SOLAR TO AC POWER SOURCE FOR REMOTE AREAS USING SEIG

    Directory of Open Access Journals (Sweden)

    MEHMET AKBABA

    2012-02-01

    Full Text Available Photovoltaic generators (PVG are increasingly used to provide electricity in remote areas. However, in many applications the DC generated electricity by a PVG need to be converted to AC. Traditionally DC to AC inverters have been widely used for this purpose. In this paper, a different system is proposed in which a self excited induction generator (SEIG driven by a permanent magnet DC motor (DCM and powered from a PVG through a maximum power point tracker (MPPT are used. A step-up chopper is utilized as an MPPT unit. The proposed system is modelled in time domain, and a detailed transient and steady-state analysis are presented. The main reason behind analyzing the system in the time domain is because of the fact that for unknown speeds, the methods developed for steady-state analysis of SEIGs can not be applied. The presented work shows that the full available power of the PVG can be harnessed by selecting suitable values for the duty cycle and the frequency of the step up chopper and the excitation capacitor of the SEIG. It is also shown that with such a combination power utilization efficiency of more than 83% can be achieved.

  2. High voltage systems (tube-type microwave)/low voltage system (solid-state microwave) power distribution

    Science.gov (United States)

    Nussberger, A. A.; Woodcock, G. R.

    1980-01-01

    SPS satellite power distribution systems are described. The reference Satellite Power System (SPS) concept utilizes high-voltage klystrons to convert the onboard satellite power from dc to RF for transmission to the ground receiving station. The solar array generates this required high voltage and the power is delivered to the klystrons through a power distribution subsystem. An array switching of solar cell submodules is used to maintain bus voltage regulation. Individual klystron dc voltage conversion is performed by centralized converters. The on-board data processing system performs the necessary switching of submodules to maintain voltage regulation. Electrical power output from the solar panels is fed via switch gears into feeder buses and then into main distribution buses to the antenna. Power also is distributed to batteries so that critical functions can be provided through solar eclipses.

  3. Single stage single phase active power factor corrected Ĉuk Topology Based AC-DC Converter

    Directory of Open Access Journals (Sweden)

    Md. Ismail Hossain

    2014-03-01

    Full Text Available This paper focuses on the analysis of a power factor correction (PFC converter using close loop Ĉuk topology. Regardless of the input line voltage and output load variations, input current drawn by the buck or buck-boost converter is always discontinuous. The Boost converter suffers from high voltage stresses across the power electronic devices. The input current in Ĉuk converter is comparable to boost converter’s input current. In this paper output voltage is controlled by inner current and outer voltage control loop along with power factor correction (PFC. It shows less input current THD, nearly unity power factor and better output voltage regulation of AC-DC converter under variable input voltage and output load. In this paper the relative performance between normal diode rectifier, open loop Ĉuk rectifier and close loop Ĉuk rectifier is presented. An algorithm for implementing close loop Ĉuk rectifier in digital domain is developed and simulated.

  4. Distributed Optimal Power Flow of AC/DC Interconnected Power Grid Using Synchronous ADMM

    Science.gov (United States)

    Liang, Zijun; Lin, Shunjiang; Liu, Mingbo

    2017-05-01

    Distributed optimal power flow (OPF) is of great importance and challenge to AC/DC interconnected power grid with different dispatching centres, considering the security and privacy of information transmission. In this paper, a fully distributed algorithm for OPF problem of AC/DC interconnected power grid called synchronous ADMM is proposed, and it requires no form of central controller. The algorithm is based on the fundamental alternating direction multiplier method (ADMM), by using the average value of boundary variables of adjacent regions obtained from current iteration as the reference values of both regions for next iteration, which realizes the parallel computation among different regions. The algorithm is tested with the IEEE 11-bus AC/DC interconnected power grid, and by comparing the results with centralized algorithm, we find it nearly no differences, and its correctness and effectiveness can be validated.

  5. Comparative Study of AC/DC High Voltage Transmissions%高压交直流输电比较研究

    Institute of Scientific and Technical Information of China (English)

    王红刚

    2011-01-01

    比较了高压交流输电和高压直流输电的差异,认为,输送同样的电能,高压直流输电损耗少的原因在于载流子在晶格势场中的能态低;由于载流子受到感应电场的作用,高压交流输电载流子在晶格势场中的能态将高于高压直流输电载流子的能态。不论高压交流输电还是高压直流输电都存在着趋肤效应,直流趋肤效应起源于载流子受到的霍尔电场力;交流趋肤效应起源于载流子除了受到霍尔电场力外,还受到了交变电场力的作用.%Comparing the differences between AC and DC high voltage transmissions,it is considered that the reason why the DC high voltage transmission has lower electrical loss in transmitting the same power is that its carriers have low energy state in lattice potential field.As the carriers being affected by induced electric field,carriers of AC will have higher energy state than that of DC in lattice potential field.No matter AC or DC high voltage transmission there is skin effect.The DC skin effect originates from Hall electric field force acting on the carriers,while the AC skin effect originates from not only Hall electric field,but the role of alternating electric field force.

  6. Proposal and Development of a High Voltage Variable Frequency Alternating Current Power System for Hybrid Electric Aircraft

    Science.gov (United States)

    Sadey, David J.; Taylor, Linda M.; Beach, Raymond F.

    2017-01-01

    The development of ultra-efficient commercial vehicles and the transition to low-carbon emission propulsion are seen as strategic thrust paths within NASA Aeronautics. A critical enabler to these paths comes in the form of hybrid electric propulsion systems. For megawatt-class systems, the best power system topology for these hybrid electric propulsion systems is debatable. Current proposals within NASA and the Aero community suggest using a combination of alternating current (AC) and direct current (DC) for power generation, transmission, and distribution. This paper proposes an alternative to the current thought model through the use of a primarily high voltage AC power system, supported by the Convergent Aeronautics Solutions (CAS) Project. This system relies heavily on the use of doubly-fed induction machines (DFIMs), which provide high power densities, minimal power conversion, and variable speed operation. The paper presents background on the activity along with the system architecture, development status, and preliminary results.

  7. Experimental Investigations on PV Powered SVM-DTC Induction Motor without AC Phase Current Sensors

    Directory of Open Access Journals (Sweden)

    T. Muthamizhan

    2014-05-01

    Full Text Available The paper presents a low-cost, phase-current reconstruction algorithm for space vector modulated direct torque controlled induction motor using the information obtained from only one shunt resistor which is in series with low side switches in a conventional three-phase inverter. The aim is to develop a low-cost high - performance induction motor drive. It uses the dc-link voltage and dc current to reconstruct the stator currents needed to estimate the motor flux and the electromagnetic torque. Photovoltaic arrays convert solar power to dc electric power; uses chopper and dc-ac inverter to fed three phase Induction Motor. The chopper used here is current fed full bridge boost dc-dc converter, which is preferred and extensively used in high voltage applications and advantageous over voltage fed converters. The inverter switches are controlled by PWM techniques obtained from SVM-DTC of IM. The experimental investigations are given to prove the ability of the proposed scheme of reproducing the performances of a SVM- DTC IM drive.

  8. ENHANCEMENT OF VOLTAGE STABILITY AND REDUCTION OF POWER LOSS USING GENETIC ALGORITHM THROUGH OPTIMAL LOCATION OF SVC, TCSC AND UPFC

    Directory of Open Access Journals (Sweden)

    R.KALAIVANI

    2016-10-01

    Full Text Available Due to huge increase in power demand, power system network will lead to major problems such as voltage instability and voltage collapse in the power system. To overcome these problems, Flexible AC Transmission System (FACTS devices have been implemented in power system. By placing these devices in suitable locations, the power system can be operated far away from the instability point. In this paper, the optimal location and the ratings of FACTS devices such as Thyristor Controlled Series Capacitor (TCSC, Static VAR Compensator (SVC and Unified Power Flow Controller (UPFC are determined using Genetic Algorithm (GA. A multi objective optimization problem is formulated with the consideration of minimizing voltage stability index, real power loss and generator cost. Evolutionary algorithm such as GA is a population based search method is used for solving multi objective optimization problem that is capable of searching for multiple solutions concurrently in a single run and provide an optimal solution. It is observed from the results that the voltages stability index, real power loss and generator cost are reduced by optimally locating the FACTS devices in the power system. IEEE 14 bus and IEEE 57 bus systems are used to demonstrate the effectiveness of the proposed algorithm.

  9. Hysteresis Current Control Based Shunt Active Power Filter for Six Pulse Ac/Dc Converter

    Directory of Open Access Journals (Sweden)

    Rakesh Kumar Pandey

    2017-02-01

    Full Text Available In this paper the simulation of Shunt Active power Filter using P-Q theory and PI controller has been presented. This SAPF compensates the harmonic currents drawn by three phase six pulse AC/DC converter. The process of compensation is done by calculating the instantaneous reactive power losses using p-q theory and the PI controller to reduce the ripple voltage of the dc capacitor of the PWM-VSI. This approach is different from conventional approach and provides very effective solution. In this simulation we use hysteresis band current controller (HCC for switching the VSI inverter. The simulation has been done for both steady state and transient conditions

  10. Preparation of Power Distribution System for High Penetration of Renewable Energy Part I. Dynamic Voltage Restorer for Voltage Regulation Pat II. Distribution Circuit Modeling and Validation

    Science.gov (United States)

    Khoshkbar Sadigh, Arash

    Part I: Dynamic Voltage Restorer In the present power grids, voltage sags are recognized as a serious threat and a frequently occurring power-quality problem and have costly consequence such as sensitive loads tripping and production loss. Consequently, the demand for high power quality and voltage stability becomes a pressing issue. Dynamic voltage restorer (DVR), as a custom power device, is more effective and direct solutions for "restoring" the quality of voltage at its load-side terminals when the quality of voltage at its source-side terminals is disturbed. In the first part of this thesis, a DVR configuration with no need of bulky dc link capacitor or energy storage is proposed. This fact causes to reduce the size of the DVR and increase the reliability of the circuit. In addition, the proposed DVR topology is based on high-frequency isolation transformer resulting in the size reduction of transformer. The proposed DVR circuit, which is suitable for both low- and medium-voltage applications, is based on dc-ac converters connected in series to split the main dc link between the inputs of dc-ac converters. This feature makes it possible to use modular dc-ac converters and utilize low-voltage components in these converters whenever it is required to use DVR in medium-voltage application. The proposed configuration is tested under different conditions of load power factor and grid voltage harmonic. It has been shown that proposed DVR can compensate the voltage sag effectively and protect the sensitive loads. Following the proposition of the DVR topology, a fundamental voltage amplitude detection method which is applicable in both single/three-phase systems for DVR applications is proposed. The advantages of proposed method include application in distorted power grid with no need of any low-pass filter, precise and reliable detection, simple computation and implementation without using a phased locked loop and lookup table. The proposed method has been verified

  11. Power Quality Improvement And Mitigation Of Voltage Sag And Current Swell Using Distributed Power Flow Controller

    Directory of Open Access Journals (Sweden)

    P.NIRMALA

    2014-09-01

    Full Text Available Modern power utilities have to respond to a number of challenges such as growth of electricity demand specially in non-linear loads in power grids, consequently, That higher power quality should be considered. In this paper, DPFC which is similar to unified power flow controller (UPFC in structure, which is used to mitigate the voltage sag and swell as a power quality issue. Unlike UPFC, the common dc-link in DPFC, between the shunt and series converter devices should be eliminated and three-phase series converter is divided to several single-phase series distributed converters through the power transmission line. And also to detect the voltage sags and find out the three single-phase reference voltages of DPFC, the synchronous reference frame method is proposed. Application of DPFC in power quality enhancement is simulated in Mat lab/Simulink environment which show the effectiveness of the proposed structure

  12. Spatial and temporal instabilities in high voltage power devices

    Energy Technology Data Exchange (ETDEWEB)

    Milady, Saeed

    2010-01-29

    Dynamic avalanche can occur during the turn-off process of high voltage bipolar devices, e.g. IGBTs and p{sup +}n{sup -}n{sup +} power diodes, that may result in spatial instabilities of the homogeneous current density distribution across the device and the formation of current filaments. Filaments may cause the destruction of the device, mainly because of the high local temperatures. The first part of this work is dedicated to the current filament behavior. The positive feedback mechanisms caused by the transient current flow through the gate capacitance of an IGBT operating under short circuit conditions may result in oscillations and temporal instabilities of the IGBT current. The oscillations may cause electromagnetic interference (EMI). Furthermore, the positive feedback mechanism may accelerate the over-heating of the device and result in a thermal run-away. This is the subject of the second part of this work. In the first part of this work using the device simulation results of power diodes the underlying physical mechanisms of the filament dynamic is investigated. Simulation results of diode structures with evenly distributed doping inhomogeneities show that, the filament motion gets smoother as the distance between the inhomogeneities decreases. Hopping to faraway inhomogeneities turns into the hopping to neighboring ones and finally a smooth motion. In homogeneous structures the slow inhibitory effect of the electron-hole plasma extraction and the fast activation, due to hole current flowing along the filament, result in a smooth filament motion. An analytical model for the filament velocity under isothermal conditions is presented that can reproduce the simulation data satisfactorily. The influence of the boundary conditions on the filament behavior is discussed. The positive beveled edge termination prohibits a long stay of the filament at the edge reducing the risk of filament pinning. Self-heating effects may turn the initially electrically triggered

  13. Wind Power Impact to Transient and Voltage Stability of the Power System in Eastern Denmark

    DEFF Research Database (Denmark)

    Rasmussen, Joana; Jørgensen, Preben; Palsson, Magni Thor

    2005-01-01

    Voltage stability, transient stability and reactive power compensation are extremely important issues for largescale integration of wind power in areas distant from the main transmission system in Eastern Denmark. This paper describes the application of a dynamic wind farm model in simulation...... studies for assessments of a large wind power penetration. The simulation results reveal problems with voltage stability due to the characteristic of wind turbine generation as well as the inability of the power system to meet the reactive power demand. Furthermore, the established model is applied...... to analyse challenges in system protection as means to reduce the risk of widespread blackouts....

  14. Low Power Low Voltage Bulk Driven Balanced OTA

    Directory of Open Access Journals (Sweden)

    Neha Gupta

    2012-01-01

    Full Text Available The last few decades, a great deal of attention has been paid to low-voltage (LV low-power (LP integrated circuits design since the power consumption has become a critical issue. Among many techniques used for the design of LV LP analog circuits, the Bulk-driven principle offers a promising route towards this design for many aspects mainly the simplicity and using the conventional MOS technology to implement these designs. This paper is devoted to the Bulk-driven (BD principle and utilizing this principle to design LV LP building block of Operational Transconductance Amplifier (OTA in standard CMOS processes and supply voltage 0.9V. The simulation results have been carried out by the Spice simulatorusing the 130nm CMOS technology from TSMC.

  15. Low Power Low Voltage Bulk Driven Balanced OTA

    Directory of Open Access Journals (Sweden)

    Neha Gupta

    2011-12-01

    Full Text Available The last few decades, a great deal of attention has been paid to low-voltage (LV low-power (LP integrated circuits design since the power consumption has become a critical issue. Among many techniques used for the design of LV LP analog circuits, the Bulk-driven principle offers a promising route towards this design for many aspects mainly the simplicity and using the conventional MOS technology to implement these designs. This paper is devoted to the Bulk-driven (BD principle and utilizing this principle to design LV LP building block of Operational Trans conductance Amplifier (OTA in standard CMOS processes and supply voltage 0.9 V. The simulation results have been carried out by the Spice simulator using the 130 nm CMOS technology from TSMC.

  16. Low Power Low Voltage Bulk Driven Balanced OTA

    CERN Document Server

    Gupta, Neha; Suthar, Meenakshi; Soni, Priyanka

    2012-01-01

    The last few decades, a great deal of attention has been paid to low-voltage (LV) low-power (LP) integrated circuits design since the power consumption has become a critical issue. Among many techniques used for the design of LV LP analog circuits, the Bulk-driven principle offers a promising route towards this design for many aspects mainly the simplicity and using the conventional MOS technology to implement these designs. This paper is devoted to the Bulk-driven (BD) principle and utilizing this principle to design LV LP building block of Operational Transconductance Amplifier (OTA) in standard CMOS processes and supply voltage 0.9V. The simulation results have been carried out by the Spice simulator using the 130nm CMOS technology from TSMC.

  17. Optimal Distributed Voltage Regulation in Power Distribution Networks

    CERN Document Server

    Lam, Albert Y S; Dominguez-Garcia, Alejandro; Tse, David

    2012-01-01

    In this paper, we address the problem of voltage regulation in power distribution networks with deep-penetration of distributed energy resources (DERs), e.g., renewable-based generation, and storage-capable loads such as plug-in hybrid electric vehicles. We cast the problem as an optimization program, where the objective is to minimize the losses in the network subject to constraints on bus voltage magnitudes, limits on active and reactive power injections, transmission line thermal limits and losses. We provide sufficient conditions under which the optimization problem can be solved via its convex relaxation. Using data from existing networks, we show that the conditions are expected to be satisfied by most networks. We also provide an efficient distributed algorithm to solve the problem. The algorithm is asynchronous, with a communication topology that is the same as the electrical network topology. We illustrate the algorithm's performance in the IEEE 34-bus and the 123-bus feeder test systems.

  18. Noise-Induced Voltage Collapse in Power Systems

    Institute of Scientific and Technical Information of China (English)

    WEI Du-Qu; LUO Xiao-Shu; ZHANG Bo

    2012-01-01

    We investigate numerically the influences of Gaussian white noise on the dynamical behaviors of power systems.The studied model is a three-bus system at some specific parameters,and it demonstrates a stable regime that is far from collapse.It is found that with the increasing noise intensity σ,power systems become unstable and fall into oscillations; as σ is further increased,noise-induced voltage collapse in power systems takes place.Our results confirm that the presence of noise has a detrimental effect on power system operation.Furthermore,the possible mechanism behind the action of noise is addressed based on a dynamical approach where the bifurcation of the system is analyzed.Our results may provide useful information for avoiding instability problems in power systems.

  19. 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)

  20. Hybrid zero-voltage switching (ZVS) control for power inverters

    Science.gov (United States)

    Amirahmadi, Ahmadreza; Hu, Haibing; Batarseh, Issa

    2016-11-01

    A power inverter combination includes a half-bridge power inverter including first and second semiconductor power switches receiving input power having an intermediate node therebetween providing an inductor current through an inductor. A controller includes input comparison circuitry receiving the inductor current having outputs coupled to first inputs of pulse width modulation (PWM) generation circuitry, and a predictive control block having an output coupled to second inputs of the PWM generation circuitry. The predictive control block is coupled to receive a measure of Vin and an output voltage at a grid connection point. A memory stores a current control algorithm configured for resetting a PWM period for a switching signal applied to control nodes of the first and second power switch whenever the inductor current reaches a predetermined upper limit or a predetermined lower limit.

  1. Characteristic Analysis of Partial Discharges and Dissolved Gases Generated Cavityin Oil-paper Insulation Under AC-DC Combined Voltages

    Institute of Scientific and Technical Information of China (English)

    HE Zhiman; LI Jian; BAO Lianwei; JIANG Tianyan; WANG Youyuan

    2012-01-01

    Oil-paper insulation is used within most of high voltage direct current(HVDC) converter transformers.Partial discharge(PD) in oil-paper insulation is a major reason for the development of internal faults in HVDC converter transformer,while PDs in oil-paper insulation mainly occur in terms of gas cavity discharges.There are few study results on the development characteristics of partial discharges in oil-paper insulation and dissolved gases in oils of HVDC converter transformers.Based on a gas cavity discharge model of oil-paper insulation,the present study investigates the development characteristics of partial discharges under AC-DC combined voltages and emphatically examines the variation characteristics of dissolved gases in the discharge development process.Experiment and analysis results show that the characteristics of partial discharges and dissolved gases in oils under AC-DC combined voltages are appreciably different with those under AC voltage.These results provide theoretical support for further research on partial discharges and on dissolved gases of other internal insulating defects and are helpful for the fault diagnosis of HVDC converter transformers.

  2. Optimizing efficiency on conventional transformer based low power AC/DC standby power supplies

    DEFF Research Database (Denmark)

    Nielsen, Nils

    2004-01-01

    This article describes the research results for simple and cheap methods to reduce the idle- and load-losses in very low power conventional transformer based power supplies intended for standby usage. In this case "very low power" means 50 Hz/230 V-AC to 5 V-DC@1 W. The efficiency is measured...... on two common power supply topologies designed for this power level. The two described topologies uses either a series (or linear) or a buck regulation approach. Common to the test power supplies is they either are using a standard cheap off-the-shelf transformer, or one, which are loss optimized by very...

  3. Simulation of Reactive Power Imbalances in the Transmission Power Grid Threatened by the Problem of Voltage Instability

    OpenAIRE

    Robert Lis; Mirosław Łabuzek

    2013-01-01

    The reactive power balance in the transmission power grid depends on the reactive power produced by the power stations and the value generated by the capacitive power lines and static compensators. Reactive transmission losses become greater than shunt capacitive generation at the turning-point of voltage stability. Then lowering bus voltages drive EPS into voltage collapse point. The paper presents the balance of reactive power depending on the power demand growth, which is then used to esti...

  4. Continuation Power Flow Method based Assessment of Static Voltage Stability considering the Power System Contingencies

    OpenAIRE

    Khan Aafreen; Tiwari Prasad Shankarshan

    2014-01-01

    Power system security is recognized as one of the major problems in many power systems throughout the world. Power system insecurity such as transmission lines being overloaded causes transmission elements cascade outages, which may lead to complete blackout. In accordance with these reasons, the prediction and recognition of voltage instability in power system has particular importance and it makes the network security stronger. This work, by considering the power system continge...

  5. 30 CFR 75.812-2 - High-voltage power centers and transformers; record of examination.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false High-voltage power centers and transformers... High-Voltage Distribution § 75.812-2 High-voltage power centers and transformers; record of examination... record shall be kept in a book approved by the Secretary. High-Voltage Longwalls Source: 67 FR 11001,...

  6. Enhancing power transfer capability through flexible AC transmission system devices:a review

    Institute of Scientific and Technical Information of China (English)

    Fadi M ALBATSH; Saad MEKHILEF; Shameem AHMAD; H MOKHLIS; M A HASSAN

    2015-01-01

    Global demand for power has significantly increased, but power generation and transmission capacities have not increased proportionally with this demand. As a result, power consumers suffer from various problems, such as voltage and frequency instability and power quality issues. To overcome these problems, the capacity for available power transfer of a transmission network should be enhanced. Researchers worldwide have addressed this issue by using flexible AC transmission system (FACTS) devices. We have conducted a comprehensive review of how FACTS controllers are used to enhance the avail-able transfer capability (ATC) and power transfer capability (PTC) of power system networks. This review includes a discussion of the classification of different FACTS devices according to different factors. The popularity and applications of these devices are discussed together with relevant statistics. The operating principles of six major FACTS devices and their application in increasing ATC and PTC are also presented. Finally, we evaluate the performance of FACTS devices in ATC and PTC im-provement with respect to different control algorithms.

  7. Power-Voltage Characteristics of Power System with the Long Transmission Line

    Directory of Open Access Journals (Sweden)

    Prechanon Kumkratug

    2012-01-01

    Full Text Available Problem statement: Power- Voltage curve provides very important information for voltage stability analysis. The exact long transmission line model consists of the resistance and the reactance. The resistance causes in the active line loss. It is not easy task to achieve the power-voltage curve characteristics of power system with the exact long line model. Approach: This study applies the concept of the Newton-Raphson method to iteratively solve the nonlinear power flow equations. The Power-Voltage (P-V curve characteristic of the system without line loss and with line loss are plotted and compared on various cases. Results: It is found from the study that the resistance of the line obviously provides the negative effects on the voltage stability. The line loss causes in the decrement of the critical point. In addition, it is found that the leading power factor can increase the critical point of P-V curve. Conclusion: The exact long line model should be considered for voltage stability analysis of the system with the long transmission line.

  8. The Space Charge Effect on the Discharge Current in Cross-Linked Polyethylene under High AC Voltages

    Science.gov (United States)

    Kwon, Yoon-Hyeok; Hwangbo, Seung; Lee, June-Ho; Yi, Dong-Young; Han, Min-Koo

    2003-12-01

    The space charge distributions in solid dielectrics have been usually investigated by means of the pulsed electroacoustic (PEA) method. However, most previous studies have been limited to the phenomenological analysis under DC voltages. In our study, the space charge distribution in cross-linked polyethylene (XLPE) has been measured using AC voltages by means of the modified PEA method. Simultaneously, the streamer discharges in an air gap have been measured in order to investigate the relationship between space charge and discharge current, and the relationship has been adapted to the case of dielectric barrier discharge. At high AC voltages, discharge current increases to the critical point, but no further increase is exhibited over the critical voltage and the discharge pattern is resolved by the space charge. This result indicates that the frequency effect and space charge characteristics of dielectric materials are preferred to the voltage effect in the adaptation to dielectric barrier discharge. The results well explain the space charge effect on partial discharge and the dielectric barrier discharge phenomenon.

  9. Voltage Control in Wind Power Plants with Doubly Fed Generators

    DEFF Research Database (Denmark)

    Garcia, Jorge Martinez

    In this work, the process of designing a wind power plant composed of; doubly fed induction generators, a static compensator unit, mechanically switched capacitors and on-load tap changer, for voltage control is shown. The selected control structure is based on a decentralized system, since...... supplied by the doubly fed induction generator wind turbines is overcome by installing a reactive power compensator, i.e. a static compensator unit, which is coordinated with the plant control by a specific dispatcher. This dispatcher is set according to the result of the wind power plant load flow....... To release the operation of the converters during steady-state disturbances, mechanically switched capacitors are installed in the wind power plant, which due to their characteristics, they are appropriate for permanent disturbances compensation. The mechanically switched capacitors are controlled to allow...

  10. Evaluation of E-J characteristics of YBCO coated-conductor by AC inductive method using third-harmonic voltage

    Energy Technology Data Exchange (ETDEWEB)

    Fukumoto, Yosuke; Kiuchi, M.; Otabe, E.S.; Matsushita, T.; Sawa, H.; Inoue, M.; Kiss, T.; Iijima, Y.; Kakimoto, K.; Saitoh, T

    2004-10-01

    The E-J characteristics were measured for a YBCO coated-conductor by using AC inductive method of third-harmonic voltage. The results are compared with the measurements obtained by the four probe method and DC relaxation method of magnetization. The results by three kinds of measurements meet approximately on a single curve and E-J curve in a wide range of electric field is obtained. Hence, the third-harmonic voltage method is useful for a continuous measurement of J{sub c} property of long coated tape. The obtained E-J characteristics are argued.

  11. Pulse doubling in zigzag-connected autotransformer-based 12-pulse ac-dc converter for power quality improvement

    Science.gov (United States)

    Abdollahi, Rohollah

    2012-12-01

    This paper presents a pulse doubling technique in a 12-pulse ac-dc converter which supplies direct torque controlled motor drives (DTCIMDs) in order to have better power quality conditions at the point of common coupling. The proposed technique increases the number of rectification pulses without significant changes in the installations and yields in harmonic reduction in both ac and dc sides. The 12-pulse rectified output voltage is accomplished via two paralleled six-pulse acdc converters each of them consisting of three-phase diode bridge rectifiers. An autotransformer is designed to supply the rectifiers. The design procedure of magnetics is in a way such that makes it suitable for retrofit applications where a six-pulse diode bridge rectifier is being utilized. Independent operation of paralleled diode-bridge rectifiers, i.e. dc-ripple re-injection methodology, requires a Zero Sequence Blocking Transformer (ZSBT). Finally, a tapped interphase reactor is connected at the output of ZSBT to double the pulse numbers of output voltage up to 24 pulses. The aforementioned structure improves power quality criteria at ac mains and makes them consistent with the IEEE-519 standard requirements for varying loads. Furthermore, near unity power factor is obtained for a wide range of DTCIMD operation. A comparison is made between 6-pulse, 12-pulse, and proposed converters from view point of power quality indices. Results show that input current total harmonic distortion (THD) is less than 5% for the proposed topology at various loads.

  12. A Secondary Voltage Control Method for an AC/DC Coupled Transmission System Based on Model Predictive Control

    DEFF Research Database (Denmark)

    Xu, Fengda; Guo, Qinglai; Sun, Hongbin;

    2015-01-01

    to keep the voltage of the pilot bus tracking its set point considering the DC system’s transmission schedule change. The approach is inspired by model predictive control (MPC) to compensate for predictable voltage change affected by DC side transmission power flow and the potential capacitor switching...

  13. PV Power-Generation System with a Phase-Shift PWM Technique for High Step-Up Voltage Applications

    Directory of Open Access Journals (Sweden)

    Cheng-Tao Tsai

    2012-01-01

    Full Text Available A PV power-generation system with a phase-shift pulse-width modulation (PWM technique for high step-up voltage applications is proposed. The proposed power-generation system consists of two stages. In the input stage, all power switches of the full-bridge converter with phase-shift technique can be operated with zero-current switching (ZCS at turn-on or turn-off transition. Hence, the switching losses of the power switches can be reduced. Then, in the DC output stage, a voltage-doubler circuit is used to boost a high dc-link bus voltage. To supply a utility power, a dc/ac inverter is connected to induce a sinusoidal source. In order to draw a maximum power from PV arrays source, a microcontroller is incorporated with the perturbation and observation method to implement maximum power point tracking (MPPT algorithm and power regulating scheme. In this study, a full load power of 300 W prototype has been built. Experimental results are presented to verify the performance and feasibility of the proposed PV power-generation system.

  14. A new type of accelerator power supply based on voltage-type space vector PWM rectification technology

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Fengjun, E-mail: wufengjun@impcas.ac.cn [Institute of Modern Physics, CAS, Lanzhou 730000 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Gao, Daqing; Shi, Chunfeng; Huang, Yuzhen [Institute of Modern Physics, CAS, Lanzhou 730000 (China); Cui, Yuan [Institute of Modern Physics, CAS, Lanzhou 730000 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Yan, Hongbin [Institute of Modern Physics, CAS, Lanzhou 730000 (China); Zhang, Huajian [Institute of Modern Physics, CAS, Lanzhou 730000 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Wang, Bin [University of Chinese Academy of Sciences, Beijing 100049 (China); Li, Xiaohui [Institute of Modern Physics, CAS, Lanzhou 730000 (China)

    2016-08-01

    To solve the problems such as low input power factor, a large number of AC current harmonics and instable DC bus voltage due to the diode or thyristor rectifier used in an accelerator power supply, particularly in the Heavy Ion Research Facility in Lanzhou-Cooler Storage Ring (HIRFL-CSR), we designed and built up a new type of accelerator power supply prototype base on voltage-type space vector PWM (SVPWM) rectification technology. All the control strategies are developed in TMS320C28346, which is a digital signal processor from TI. The experimental results indicate that an accelerator power supply with a SVPWM rectifier can solve the problems above well, and the output performance such as stability, tracking error and ripple current meet the requirements of the design. The achievement of prototype confirms that applying voltage-type SVPWM rectification technology in an accelerator power supply is feasible; and it provides a good reference for design and build of this new type of power supply. - Highlights: • Applying SVPWM rectification technology in an accelerator power supply improves its grid-side performance. • New Topology and its control strategies make an accelerator power supply have bidirectional power flow ability. • Hardware and software of controller provide a good reference for design of this new type of power supply.

  15. Study of the Dependence on Magnetic Field and Bias Voltage of an AC-Biased TES Microcalorimeter

    Science.gov (United States)

    Bandler, Simon

    2011-01-01

    At SRON we are studying the performance of a Goddard Space Flight Center single pixel TES microcalorimeter operated in the AC bias configuration. For x-ray photons at 6keV the AC biased pixel shows a best energy resolution of 3.7eV, which is about a factor of 2 worse than the energy resolution observed in identical DC-biased pixels. To better understand the reasons of this discrepancy, we investigated the detector performance as a function of temperature, bias working point and applied magnetic field. A strong periodic dependence of the detector noise on the TES AC bias voltage is measured. We discuss the results in the framework of the recent weak-link behaviour observed inTES microcalorimeters.

  16. Efficient relaxations for joint chance constrained AC optimal power flow

    Energy Technology Data Exchange (ETDEWEB)

    Baker, Kyri; Toomey, Bridget

    2017-07-01

    Evolving power systems with increasing levels of stochasticity call for a need to solve optimal power flow problems with large quantities of random variables. Weather forecasts, electricity prices, and shifting load patterns introduce higher levels of uncertainty and can yield optimization problems that are difficult to solve in an efficient manner. Solution methods for single chance constraints in optimal power flow problems have been considered in the literature, ensuring single constraints are satisfied with a prescribed probability; however, joint chance constraints, ensuring multiple constraints are simultaneously satisfied, have predominantly been solved via scenario-based approaches or by utilizing Boole's inequality as an upper bound. In this paper, joint chance constraints are used to solve an AC optimal power flow problem while preventing overvoltages in distribution grids under high penetrations of photovoltaic systems. A tighter version of Boole's inequality is derived and used to provide a new upper bound on the joint chance constraint, and simulation results are shown demonstrating the benefit of the proposed upper bound. The new framework allows for a less conservative and more computationally efficient solution to considering joint chance constraints, specifically regarding preventing overvoltages.

  17. Design of 6 W isolated flyback AC/DC power supply%6W隔离反激式AC/DC电源设计

    Institute of Scientific and Technical Information of China (English)

    冯欣宇; 黄阿娟

    2015-01-01

    介绍了基于UCC28910的5 V/1.2 A隔离反激式开关电源.电路结构简单,所需外部元件较少,有效减少了电路板占用面积.电源可实现AC 85~265 V宽电压输入,在无需光耦合器的情况下实现恒定电压与恒定电流输出.具有700 V高压启动和小于30 mW待机功耗的特点.采用DCM模式减少开关损耗,符合Energy StarEPS 2.0标准.%The design of 5 V/1.2 A isolated flyback switching power supply based on UCC28910 is introduced. Its circuit structure is simple and fewer external components are required,which reduces the area occupied by PCB effectively. The power supply can accepts a wide range voltage input of 85 VAC to 265 VAC. The constant voltage and current output was realized without any opto-coupler. This device has characteristics of 700 V high-voltage start and less than 30 mW standby power loss. DCM mode is used to reduce the switching loss,which is consistent with the standard of Energy Star EPS2.0.

  18. Application of Newton's optimal power flow in voltage/reactive power control

    Energy Technology Data Exchange (ETDEWEB)

    Bjelogrlic, M.; Babic, B.S. (Electric Power Board of Serbia, Belgrade (YU)); Calovic, M.S. (Dept. of Electrical Engineering, University of Belgrade, Belgrade (YU)); Ristanovic, P. (Institute Nikola Tesla, Belgrade (YU))

    1990-11-01

    This paper considers an application of Newton's optimal power flow to the solution of the secondary voltage/reactive power control in transmission networks. An efficient computer program based on the latest achievements in the sparse matrix/vector techniques has been developed for this purpose. It is characterized by good robustness, accuracy and speed. A combined objective function appropriate for various system load levels with suitable constraints, for treatment of the power system security and economy is also proposed. For the real-time voltage/reactive power control, a suboptimal power flow procedure has been derived by using the reduced set of control variables. This procedure is based on the sensitivity theory applied to the determination of zones for the secondary voltage/reactive power control and corresponding reduced set of regulating sources, whose reactive outputs represent control variables in the optimal power flow program. As a result, the optimal power flow program output becomes a schedule to be used by operators in the process of the real-time voltage/reactive power control in both normal and emergency operating states.

  19. Design of a High Power Factor Single-phase AC-DC Regulated Power Supply%一种高功率因数单相AC-DC稳压电源的设计

    Institute of Scientific and Technical Information of China (English)

    谭洁; 李恒; 沐润志

    2015-01-01

    针对目前AC-DC稳压电源转换率、稳压效果不理想,提出了一种高功率因数单相AC-DC稳压电源设计方案。以UCC28019芯片为校正核心实现有源功率因数校正,通过对BOOST主电路拓扑结构的升压电路的输入电流进行控制,使其达到与输入电压相位差为0,功率因数接近于1。本设计以单片机为控制核心,通过按键设置输出电压给定值,实时比较输出电压实测值与给定值,自动调节PWM波形占空比,进而控制MOS管的关断频率使输出电压稳定。%Aiming at the present AC-DC, the regulated power supply conversion rate and the regulated effect of it are not satisfied. This paper puts forward a kind of design scheme with high power factor single-phase AC-DC regulated power supply. The UCC28019 correction chip is the core of this design to realize the active power factor correction. In order to make the input current and the input voltage phase difference reach 0 and the power factor is close to 1, this paper uses the topology of BOOST circuit as main circuit to control the input current. At the same time, this design takes SCM as the core of the control to set up the output voltage by the button. Then, through comparing the actual output voltage and the output voltage, the waveform of PWM will be automatically adjusted and the cut-off frequency of MOS tube is controlled to ensure the stabilization of the output voltage.

  20. 21 CFR 880.5510 - Non-AC-powered patient lift.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Non-AC-powered patient lift. 880.5510 Section 880... Devices § 880.5510 Non-AC-powered patient lift. (a) Identification. A non-AC-powered patient lift is a... patient in the horizontal or other required position from one place to another, as from a bed to a...

  1. Using a nonparametric PV model to forecast AC power output of PV plants

    OpenAIRE

    Almeida, Marcelo Pinho; Perpiñan Lamigueiro, Oscar; Narvarte Fernández, Luis

    2015-01-01

    In this paper, a methodology using a nonparametric model is used to forecast AC power output of PV plants using as inputs several forecasts of meteorological variables from a Numerical Weather Prediction (NWP) model and actual AC power measurements of PV plants. The methodology was built upon the R environment and uses Quantile Regression Forests as machine learning tool to forecast the AC power with a confidence interval. Real data from five PV plants was used to validate the methodology, an...

  2. A self-powered AC magnetic sensor based on piezoelectric nanogenerator.

    Science.gov (United States)

    Yu, Aifang; Song, Ming; Zhang, Yan; Kou, Jinzong; Zhai, Junyi; Lin Wang, Zhong

    2014-11-14

    An AC magnetic field, which is a carrier of information, is distributed everywhere and is continuous. How to use and detect this field has been an ongoing topic over the past few decades. Conventional magnetic sensors are usually based on the Hall Effect, the fluxgate, a superconductor quantum interface or magnetoelectric or magnetoresistive sensing. Here, a flexible, simple, low-cost and self-powered active piezoelectric nanogenerator (NG) is successfully demonstrated as an AC magnetic field sensor at room temperature. The amplitude and frequency of a magnetic field can both be accurately sensed by the NG. The output voltage of the NG has a good linearity with a measured magnetic field. The detected minute magnetic field is as low as 1.2 × 10(-7) tesla, which is 400 times greater than a commercial magnetic sensor that uses the Hall Effect. In comparison to the existing technologies, an NG is a room-temperature self-powered active sensor that is very simple and very cheap for practical applications.

  3. 单相电压型Z源AC/AC变流器电路%Single-Phase Voltage-Fed Z-Source AC/AC Converter

    Institute of Scientific and Technical Information of China (English)

    房绪鹏

    2006-01-01

    提出了一种新型AC/AC变流器电路--单相电压型Z源AC/AC变流器;介绍了其电路拓扑、工作原理、控制方法等;给出了相应的仿真和实验结果.仿真和实验证实了该电路拓扑的合理性和优越性.

  4. An extremely low power voltage reference with high PSRR for power-aware ASICs

    Science.gov (United States)

    Jihai, Duan; Dongyu, Deng; Weilin, Xu; Baolin, Wei

    2015-09-01

    An extremely low power voltage reference without resistors is presented for power-aware ASICs. In order to reduce the power dissipation, an Oguey current reference source is used to reduce the static current; a cascode current mirror is used to increase the power supply rejection ratio (PSRR) and reduce the line sensitivity of the circuit. The voltage reference is fabricated in SMIC 0.18-μm CMOS process. The measured results for the voltage reference demonstrate that the temperature coefficient of the voltage is 66 ppm/°C in a range from 25 to 100 °C. The line sensitivity is 0.9% in a supply voltage range of 1.8 to 3.3 V, and PSRR is -49 dB at 100 Hz. The power dissipation is 200 nW. The chip area is 0.01 mm2. The circuit can be used as an elementary circuit block for power-aware ASICs. Project supported by the National Natural Science Foundation of China (Nos. 61161003, 61264001, 61166004) and the Guangxi Natural Science Foundation (No. 2013GXNSFAA019333).

  5. On the reliability of voltage and power as input parameters for the characterization of high power ultrasound applications

    Science.gov (United States)

    Haller, Julian; Wilkens, Volker

    2012-11-01

    For power levels up to 200 W and sonication times up to 60 s, the electrical power, the voltage and the electrical impedance (more exactly: the ratio of RMS voltage and RMS current) have been measured for a piezocomposite high intensity therapeutic ultrasound (HITU) transducer with integrated matching network, two piezoceramic HITU transducers with external matching networks and for a passive dummy 50 Ω load. The electrical power and the voltage were measured during high power application with an inline power meter and an RMS voltage meter, respectively, and the complex electrical impedance was indirectly measured with a current probe, a 100:1 voltage probe and a digital scope. The results clearly show that the input RMS voltage and the input RMS power change unequally during the application. Hence, the indication of only the electrical input power or only the voltage as the input parameter may not be sufficient for reliable characterizations of ultrasound transducers for high power applications in some cases.

  6. A High Power Factor Single-phase AC-DC Converter%一种高功率因数的单相AC-DC变换器

    Institute of Scientific and Technical Information of China (English)

    李雨; 丁志勇; 李鹏鹏

    2014-01-01

    设计了一种有源功率因数校正(APFC)的高功率因数单相AC-DC变换器。该系统以TI公司专用APFC控制芯片UCC28019为控制核心,实现BOOST式APFC,后级以高效控制芯片TPS54360为控制器,输出恒压36 V,最大输出电流为2.5 A。该系统采用STC12C5A60S2单片机为监测控制中心,具有输出过流保护和功率因数、输出电压、输出电流实时测量和显示功能。在设计时,该系统从布局布线和滤波等方面消除了电磁干扰,使电压调整率和负载调整率都在0.5%以下,工作性能稳定、可靠。%An active Power Factor Correction(APFC)high power factor single-phase AC-DC converter. The system is dedicated to TI’s UCC28019 APFC control chip to control the core, to achieve BOOST type APFC, after the class in an efficient control chip TPS54360 controller, constant voltage output 36 V, maximum output current of 2.5 A. The system uses STC12C5A60S2 microcontroller monitoring control center, with output overcurrent protection and power factor, output voltage, output current, real-time measurement and display functions. In the design, the system layout and filtering from the elimination of electromagnetic interference, voltage regulation and load regulation are 0.5%, stable performance, reliable.

  7. High Current, Low Voltage Power Converter [20kA, 6V] LHC Converter Prototype

    CERN Document Server

    Jørgensen, H E; Dupaquier, A; Fernqvist, G

    1998-01-01

    The superconducting LHC accelerator requires high currents (~12.5kA) and relatively low voltages (~10 V) for its magnets. The need to install the power converters underground is the driving force for reduced volume and high efficiency. Moreover, the LHC machine will require a very high level of performance from the power converters, particularly in terms of DC stability, dynamic response and also in matters of EMC. To meet these requirements soft-switching techniques will be used. This paper describes the development of a [20kA,6V] power converter intended as a stable high-current source for D CCT calibration and an evaluation prototype for the future LHC converters. The converter is made with a modular concept with five current sources [4kA,6V] in parallel. The 4kA sources are built as plu g-in modules: a diode rectifier on the AC mains with a damped L-C passive filter, a Zero Voltage Switching inverter working at 20 kHz and an output stage (high frequency transformers, Schottky rectifi ers and output filter...

  8. 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.

  9. A Price-Based Approach for Voltage Regulation and Power Loss Minimization in Power Distribution Networks

    NARCIS (Netherlands)

    Jafarian, Matin; Scherpen, Jacquelien M.A.; Aiello, Marco

    2016-01-01

    We present a price-based approach to deal with the challenges of the electrical power distribution systems with renewable generations. In specific, we address the power loss minimization and voltage regulation taking into account the actual grid capacity. Analogously, the cost function is reformulat

  10. Dynamic voltage regulation and power export in a distribution system using distributed generation

    Institute of Scientific and Technical Information of China (English)

    Aamir HANIF; Muhammad Ahmed CHOUDHRY

    2009-01-01

    The major aim of power quality (PQ) enhancing techniques is to maintain a specified voltage magnitude at a desired frequency for sensitive loads irrespective of faults on the power distribution network. The dynamic voltage restorer (DVR) is a device used to mitigate voltage sags to regulate load voltage. This paper presents a mathematical model for leading series voltage injection to mitigate sags thereby achieving the improvement of the utility power factor as well as power sharing between the DVR and utility. The power sharing will be as per requirement to compensate the sags considering the available distributed generation (DG). The approach of mitigating voltage sags using the concept of leading series voltage injection is suitable for those locations where phase shift in the voltage will not cause any problem. The MATLAB/SIMULINK SimPowerSystem toolbox has been used to obtain simulation results to verify the proposed mathematical model.

  11. The Single-Phase AC-DC Conversion Circuit with Power Factor Adjustable%功率因数可调单相AC-DC变换电路∗

    Institute of Scientific and Technical Information of China (English)

    杨力; 张师斌; 赵宁

    2015-01-01

    基于UCC28019A设计的功率因数可调单相AC-DC变换电路。 MSP430单片机作为其控制核心,使用高精度24 bitΣ-Δ型ADC采样,可完成对输入电压有效值、输入电流有效值、有功功率有效值、功率因数等参数的测量。由UCC28019A完成功率因数的校正,通过控制数字移相电路对外围电流反馈信号移相,实现功率因数在0.8~1.0范围内的调整。本设计还可通过对输出电流和电压的监测,实现2.5 A过流保护和36 V稳压输出的功能。%This design is a single-phase AC-DC conversion circuit with power factor adjustable based on UCC28019A. MSP430 is selected as the control core. We adopt the high precision 24-bitΣ-ΔADC to measure the input voltage RMS,the input current RMS,the active power RMS,the power factor and some other parameters. The power-factor correction is accomplished by UCC28019A. By controlling the digital phase shift circuit to shift the phase of the current feedback signal,the power factor can be set in the range of 0.8 to 1.0. By detecting the output current and voltage,the circuit has the function of 2.5A overcurrent protection and 36V regulated output.

  12. Analysis of crowbar action of high voltage DC power supply in the LHD ICRF system

    Energy Technology Data Exchange (ETDEWEB)

    Li Xiaodong [Southwestern Institute of Physics, Chengdu, Sichuan (China); Mutoh, T.; Kumazawa, R.; Watari, T.; Seki, T.; Shimpo, F.; Nomura, G.; Saito, K.

    1999-04-01

    Ion Cyclotron Range of Frequency (ICRF) heating will be applied to the Large Helical Device (LHD) at the 2nd experimental campaign in 1998. The LHD ICRF system is characterised by its high power (up to 12 MW at final stage) and steady state operation for more than 30 minutes. One of the main R and D items was a high power and steady state transmitter. The RF transmitter system having a wide frequency range from 25 to 95 MHz was designed and fabricated. This report describes the analysis of the DC power supply that contains the crowbar circuit protecting the tetrode from the arcing inside the tube. The DC power supply of the transmitter is fed from the commercial AC electric line which also supply the power to the LHD helical and poloidal coil power supplies. The voltage drop of the commercial line when the ICRF crowbar action happened is the serious problem for all experimental system. This paper analyses the crowbar effect on the commercial line with and without leakage transformer between the step-up transformer of transmitter and the commercial line. (author)

  13. AC Power Routing System in Home Based on Demand and Supply Utilizing Distributed Power Sources

    Directory of Open Access Journals (Sweden)

    Takashi Hikihara

    2011-04-01

    Full Text Available To help reduce consumption of fossil fuels, renewable, natural and distributed power sources are being adopted. These alternative energy sources inevitably show fluctuations in the amount of output power, frequency, and voltage. The suppression of such fluctuations is a key issue to avoid disturbances in power grids. A similar situation arises as far as the regulation of in-home power flow is concerned. We focus on the quality of supplied and demanded power in particular. In this paper, an in-home power distribution system based on information of power is proposed. The system is developed in order to integrate power dispatch and communication. The experimental results show the feasibility of new flexible and efficient power management approaches.

  14. Continuation Power Flow Method based Assessment of Static Voltage Stability considering the Power System Contingencies

    Directory of Open Access Journals (Sweden)

    Khan Aafreen

    2014-11-01

    Full Text Available Power system security is recognized as one of the major problems in many power systems throughout the world. Power system insecurity such as transmission lines being overloaded causes transmission elements cascade outages, which may lead to complete blackout. In accordance with these reasons, the prediction and recognition of voltage instability in power system has particular importance and it makes the network security stronger. This work, by considering the power system contingencies based on the effects of them on Mega Watt Margin (MWM and maximum loading point (MLP is focused to analyse the voltage stability using continuation power flow method. The study has been carried out on IEEE 30-Bus Test System using MATLAB and PSAT softwares and results are presented.

  15. A New High Precision Power Detector of Complex Voltage Signals

    Directory of Open Access Journals (Sweden)

    Petrović Predrag B.

    2015-08-01

    Full Text Available A current-mode bipolar power detector based on a novel synthesis of translinear loop squarer/divider is presented. The circuits consist of a single multiple-output current controlled current differencing transconductance amplifier (MO-CCCDTA, two current controlled conveyors (CCCII, and one resistor and one capacitor that are both grounded. The errors related to the signal processing and errors bound were investigated and presented in the paper. The PSpice simulation and experimental results are depicted, and agree well with the theoretical anticipation. The measurement results show that the scheme improves the accuracy of the detector to better than 0.04 % and wide operating frequency range from 50 Hz to 10 MHz. The maximum power consumption of the detector is approximately 5.80 mW, at ±1.2 V supply voltages.

  16. Architecture for a High-to-Medium-Voltage Power Converter

    Science.gov (United States)

    Vorpenian, Vatche

    2008-01-01

    A power converter now undergoing development is required to operate at a DC input potential ranging between 5.5 and 10 kV and a DC output potential of 400 V at a current up to 25 A. This power converter is also required to be sufficiently compact and reliable to fit and operate within the confines of a high-pressure case to be lowered to several miles (approx.5 km) below the surface of the ocean. The architecture chosen to satisfy these requirements calls for a series/ parallel arrangement of 48 high-frequency, pulse-width-modulation (PWM), transformer-isolation DC-to-DC power converter blocks. The input sides of the converter blocks would be connected in series so that the input potential would be divided among them, each of them being exposed to an input potential of no more than 10 kV/48 . 210 V. The series connection of inputs would also enforce a requirement that all the converter blocks operate at the same input current. The outputs of the converter blocks would be connected in a matrix comprising 6 parallel legs, each leg being a cascade of eight outputs wired in series (see figure). All the converter blocks would be identical within the tolerances of the values of their components. A single voltage feedback loop would regulate the output potential. All the converter blocks would be driven by the same PWM waveform generated by this feedback loop. The power transformer of each converter block would have a unity turns ratio and would be capable of withstanding as much as 10 kVDC between its primary and secondary windings. (Although, in general, the turns ratio could be different from unity, the simplest construction for minimizing leakage and maximizing breakdown voltage is attained at a turns ratio of unity.)

  17. Requirements on medium-voltage switchgear for traction power supply; Anforderungen an Mittelspannungsschaltanlagen zur Bahnenergieversorgung

    Energy Technology Data Exchange (ETDEWEB)

    Girbert, K.H.; Loenard, D.; Northe, J. [Balfour Beatty Rail GmbH Power Systems, Offenbach (Germany)

    2003-10-01

    Differing requirements to be met by medium-voltage switchgear in conjunction with historical developments, applicable standards and regulations and customers' conditions of operation were the factors responsible for the use of open-air switchgear in outdoor and air-insulated and gas-insulated equipment in indoor environments. The requirements made today on single-phase equipment and two-phase equipment for feeding autotransformer systems are described. Priority focus in the article is given to 25 kV 50 Hz applications though the information applies to 1 AC 15 kV 16.7 Hz equipment in principle as well. The equipment is compared with that used for d.c. railways and public power supply systems. (orig.)

  18. Multi-Objective Differential Evolution for Voltage Security Constrained Optimal Power Flow in Deregulated Power Systems

    Science.gov (United States)

    Roselyn, J. Preetha; Devaraj, D.; Dash, Subhransu Sekhar

    2013-11-01

    Voltage stability is an important issue in the planning and operation of deregulated power systems. The voltage stability problems is a most challenging one for the system operators in deregulated power systems because of the intense use of transmission line capabilities and poor regulation in market environment. This article addresses the congestion management problem avoiding offline transmission capacity limits related to voltage stability by considering Voltage Security Constrained Optimal Power Flow (VSCOPF) problem in deregulated environment. This article presents the application of Multi Objective Differential Evolution (MODE) algorithm to solve the VSCOPF problem in new competitive power systems. The maximum of L-index of the load buses is taken as the indicator of voltage stability and is incorporated in the Optimal Power Flow (OPF) problem. The proposed method in hybrid power market which also gives solutions to voltage stability problems by considering the generation rescheduling cost and load shedding cost which relieves the congestion problem in deregulated environment. The buses for load shedding are selected based on the minimum eigen value of Jacobian with respect to the load shed. In the proposed approach, real power settings of generators in base case and contingency cases, generator bus voltage magnitudes, real and reactive power demands of selected load buses using sensitivity analysis are taken as the control variables and are represented as the combination of floating point numbers and integers. DE/randSF/1/bin strategy scheme of differential evolution with self-tuned parameter which employs binomial crossover and difference vector based mutation is used for the VSCOPF problem. A fuzzy based mechanism is employed to get the best compromise solution from the pareto front to aid the decision maker. The proposed VSCOPF planning model is implemented on IEEE 30-bus system, IEEE 57 bus practical system and IEEE 118 bus system. The pareto optimal

  19. 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

  20. Voltage Source Inverter/Converter for the Improvement of Power Quality Using Fuzzy Logic Controller

    Directory of Open Access Journals (Sweden)

    T Jagan Mohan Rao

    2014-05-01

    Full Text Available In recent years, the applications of power electronics have grown tremendously. These power electronic systems offer highly nonlinear characteristics. To overcome those non linearities active power filters are preferred. This paper presents and compares the performance of two controllers namely Fuzzy Logic and Proportional Integral (PI applied to a voltage source inverter / converter which operates as an active power filter. The active power filter is operated to compensate harmonics generated by the non-linear load . This work is done to make an accurate comparison of the performance of fuzzy logic controller and classical control technique such as PI controller in compensating harmonics in the ac mains current. Fuzzy control rule design is based on the general dynamic behavior of the process. A novel control method is implemented for suppressing the harmonics. The compensation process is instantaneous, which is achieved without employing any complicated control logic. The control scheme is based on sensing line currents only; an approach different from convention ones, which are based on sensing harmonics of the nonlinear load. In the control scheme a hysteresis controller based on current control is employed to generate switching signals to the PWM converter.

  1. Dispatching power system for preventive and corrective voltage collapse problem in a deregulated power system

    Science.gov (United States)

    Alemadi, Nasser Ahmed

    Deregulation has brought opportunities for increasing efficiency of production and delivery and reduced costs to customers. Deregulation has also bought great challenges to provide the reliability and security customers have come to expect and demand from the electrical delivery system. One of the challenges in the deregulated power system is voltage instability. Voltage instability has become the principal constraint on power system operation for many utilities. Voltage instability is a unique problem because it can produce an uncontrollable, cascading instability that results in blackout for a large region or an entire country. In this work we define a system of advanced analytical methods and tools for secure and efficient operation of the power system in the deregulated environment. The work consists of two modules; (a) contingency selection module and (b) a Security Constrained Optimization module. The contingency selection module to be used for voltage instability is the Voltage Stability Security Assessment and Diagnosis (VSSAD). VSSAD shows that each voltage control area and its reactive reserve basin describe a subsystem or agent that has a unique voltage instability problem. VSSAD identifies each such agent. VS SAD is to assess proximity to voltage instability for each agent and rank voltage instability agents for each contingency simulated. Contingency selection and ranking for each agent is also performed. Diagnosis of where, why, when, and what can be done to cure voltage instability for each equipment outage and transaction change combination that has no load flow solution is also performed. A security constrained optimization module developed solves a minimum control solvability problem. A minimum control solvability problem obtains the reactive reserves through action of voltage control devices that VSSAD determines are needed in each agent to obtain solution of the load flow. VSSAD makes a physically impossible recommendation of adding reactive

  2. Design and Construction of Low Cost High Voltage dc Power Supply for Constant Power Operation

    Science.gov (United States)

    Kumar, N. S.; Jayasankar, V.

    2013-06-01

    Pulsed load applications like laser based systems need high voltage dc power supplies with better regulation characteristics. This paper presents the design, construction and testing of dc power supply with 1 kV output at 300 W power level. The designed converter has half bridge switched mode power supply (SMPS) configuration with 20 kHz switching. The paper covers the design of half bridge inverter, closed loop control, High frequency transformer and other related electronics. The designed power supply incorporates a low cost OPAMP based feedback controller which is designed using small signal modelling of the converter. The designed converter was constructed and found to work satisfactorily as per the specifications.

  3. 30 CFR 56.12071 - Movement or operation of equipment near high-voltage power lines.

    Science.gov (United States)

    2010-07-01

    ...-voltage power lines. 56.12071 Section 56.12071 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION... NONMETAL MINES Electricity § 56.12071 Movement or operation of equipment near high-voltage power lines. When equipment must be moved or operated near energized high-voltage powerlines (other than...

  4. Power conditioning using dynamic voltage restorers under different voltage sag types

    Directory of Open Access Journals (Sweden)

    Ahmed M. Saeed

    2016-01-01

    Full Text Available Voltage sags can be symmetrical or unsymmetrical depending on the causes of the sag. At the present time, one of the most common procedures for mitigating voltage sags is by the use of dynamic voltage restorers (DVRs. By definition, a DVR is a controlled voltage source inserted between the network and a sensitive load through a booster transformer injecting voltage into the network in order to correct any disturbance affecting a sensitive load voltage. In this paper, modelling of DVR for voltage correction using MatLab software is presented. The performance of the device under different voltage sag types is described, where the voltage sag types are introduced using the different types of short-circuit faults included in the environment of the MatLab/Simulink package. The robustness of the proposed device is evaluated using the common voltage sag indices, while taking into account voltage and current unbalance percentages, where maintaining the total harmonic distortion percentage of the load voltage within a specified range is desired. Finally, several simulation results are shown in order to highlight that the DVR is capable of effective correction of the voltage sag while minimizing the grid voltage unbalance and distortion, regardless of the fault type.

  5. Power conditioning using dynamic voltage restorers under different voltage sag types.

    Science.gov (United States)

    Saeed, Ahmed M; Abdel Aleem, Shady H E; Ibrahim, Ahmed M; Balci, Murat E; El-Zahab, Essam E A

    2016-01-01

    Voltage sags can be symmetrical or unsymmetrical depending on the causes of the sag. At the present time, one of the most common procedures for mitigating voltage sags is by the use of dynamic voltage restorers (DVRs). By definition, a DVR is a controlled voltage source inserted between the network and a sensitive load through a booster transformer injecting voltage into the network in order to correct any disturbance affecting a sensitive load voltage. In this paper, modelling of DVR for voltage correction using MatLab software is presented. The performance of the device under different voltage sag types is described, where the voltage sag types are introduced using the different types of short-circuit faults included in the environment of the MatLab/Simulink package. The robustness of the proposed device is evaluated using the common voltage sag indices, while taking into account voltage and current unbalance percentages, where maintaining the total harmonic distortion percentage of the load voltage within a specified range is desired. Finally, several simulation results are shown in order to highlight that the DVR is capable of effective correction of the voltage sag while minimizing the grid voltage unbalance and distortion, regardless of the fault type.

  6. Study of the Dependency on Magnetic Field and Bias Voltage of an AC-Biased TES Microcalorimeter

    Science.gov (United States)

    Gottardi, L.; Bruijn, M.; denHartog, R.; Hoevers, H.; deKorte, P.; vanderKuur, J.; Linderman, M.; Adams, J.; Bailey, C.; Bandler, S.; Chervenak, J.; Eckart, M.; Finkbeiner, F.; Kelley, R.; Kilbourne, C.; Porter, F.; Sadlier, J.; Smith, S.

    2012-01-01

    At SRON we are studying the performance of a Goddard Space Flight Center single pixel TES microcalorimeter operated in an AC bias configuration. For x-ray photons at 6 keV the pixel shows an x-ray energy resolution Delta E(sub FWHM) = 3.7 eV, which is about a factor 2 worse than the energy resolution observed in an identical DC-biased pixel. In order to better understand the reasons for this discrepancy we characterized the detector as a function of temperature, bias working point and applied perpendicular magnetic field. A strong periodic dependency of the detector noise on the TES AC bias voltage is measured. We discuss the results in the framework of the recently observed weak-link behaviour of a TES microcalorimeter.

  7. Nickel-gallium arsenide high-voltage power Schottky diodes

    Science.gov (United States)

    Ashkinazi, G.; Hadas, Tz.; Meyler, B.; Nathan, M.; Zolotarevski, L.; Zolotarevski, O.

    1993-01-01

    A power GaAs Schottky diode (SD) with a chemically deposited Ni barrier was designed, fabricated and tested. The diode has a reverse breakdown voltage VBR of 140 V, forward voltage drop VF (at 50 A/cm 2) of 0.7 V at 23°C, 0.5 V at 150°C and 0.3 V at 250°C, and reverse leakage current densities jR (at -50 V) of 0.1 μA/cm 2 at 23°C and 1 mA/cm 2 at 150°C. Calculated forward and reverse I- V characteristics using a simple self-consistent computer model are in good agreement with measured values. Calculated characteristics of a silicon SD with identical structure parameters, using the same model, show much poorer VBR, VF and jR values. The theoretical maximum value of VBR is physically limited by the largest allowed VF. For a V Fof ⋍1.6 V, V BR.maxis ⋍200 V in Si and ⋍800 simple technology allows manufacturing of large area GaAs Schottky diodes with average currents up to V in GaAs SDs. Our relatively 100 A.

  8. A.c. Power Measurement Using Power Analyzer Associated with External Transducers. Accuracy and Uncertainty Evaluation

    Directory of Open Access Journals (Sweden)

    Marinel Popescu

    2014-09-01

    Full Text Available The development of the digital signal processors and their implementation in measuring technique has led to the manufacturing of power analyzers used as multifunction meters in industry, automation, tests and laboratory activities, monitoring and control of processes, etc. The parameters of a three-phase system can be known if the phase currents, the phase voltages and the phase difference between them can be known.A power analyzer has six inputs for currents and voltages measuring signals. The paper presents a method of determination of errors and uncertainties of electrical quantities measurement using a power analyzer associated with external transducers. The best estimation of measured quantity and uncertainty of measurement are used to report the result of measurement process.

  9. Application of Multi-Objective Evolutionary Algorithm for Optimal Reactive Power Dispatch with Flexible AC Transmission System Devices

    Directory of Open Access Journals (Sweden)

    Abdarrazak OUALI

    2011-12-01

    Full Text Available Because their capability to change the network parameters with a rapid response and enhanced flexibility, flexible AC transmission system (FACTS devices have taken more attention in power systems operations as improvement of voltage profile and minimizing system losses. In this way, this paper presents a multi-objective evolutionary algorithm (MOEA to solve optimal reactive power dispatch (ORPD problem with FACTS devices. This nonlinear multi-objective problem (MOP consists to minimize simultaneously real power loss in transmission lines and voltage deviation at load buses, by tuning parameters and searching the location of FACTS devices. The constraints of this MOP are divided to equality constraints represented by load flow equations and inequality constraints such as, generation reactive power sources and security limits at load buses. Two types of FACTS devices, static synchronous series compensator (SSSC and unified power flow controller (UPFC are considered. A comparative study regarding the effects of an SSSC and an UPFC on voltage deviation and total transmission real losses is carried out. The design problem is tested on a 6-bus system.

  10. A new type of accelerator power supply based on voltage-type space vector PWM rectification technology

    Science.gov (United States)

    Wu, Fengjun; Gao, Daqing; Shi, Chunfeng; Huang, Yuzhen; Cui, Yuan; Yan, Hongbin; Zhang, Huajian; Wang, Bin; Li, Xiaohui

    2016-08-01

    To solve the problems such as low input power factor, a large number of AC current harmonics and instable DC bus voltage due to the diode or thyristor rectifier used in an accelerator power supply, particularly in the Heavy Ion Research Facility in Lanzhou-Cooler Storage Ring (HIRFL-CSR), we designed and built up a new type of accelerator power supply prototype base on voltage-type space vector PWM (SVPWM) rectification technology. All the control strategies are developed in TMS320C28346, which is a digital signal processor from TI. The experimental results indicate that an accelerator power supply with a SVPWM rectifier can solve the problems above well, and the output performance such as stability, tracking error and ripple current meet the requirements of the design. The achievement of prototype confirms that applying voltage-type SVPWM rectification technology in an accelerator power supply is feasible; and it provides a good reference for design and build of this new type of power supply.

  11. 移动基站交流稳压技术探讨%Discussion on the AC Voltage Stabilization in the Mobile Stations

    Institute of Scientific and Technical Information of China (English)

    黄坤材

    2001-01-01

    Aiming at the national bad status of AC power to the telecom power, the paper dis cusses some issues which should be careful when the mobile base stations select the AC voltage stabilizer, introduces and analysises in detail the performance of various national made stabilizer,such as, mechanic adjustable compensation stabilizer, parameter stabilizer, inductive stabilizer,silicon-control compensation stabilizer. At last, it presents the proposal on the selection of the stabilizer to the mobile base stations.%针对我国通信电源交流供电状况不良的现状,论述了移动通信基站交流稳压器选型应注意的几个问题,详细介绍了国内生产的机械调压补偿式稳压器、参数稳压器、感应式稳压器、可控硅补偿式稳压器等产品性能,并进行了比较。最后提出了移动通信基站交流稳压器选型的建议。

  12. Dynamic power flow controllers

    Science.gov (United States)

    Divan, Deepakraj M.; Prasai, Anish

    2017-03-07

    Dynamic power flow controllers are provided. A dynamic power flow controller may comprise a transformer and a power converter. The power converter is subject to low voltage stresses and not floated at line voltage. In addition, the power converter is rated at a fraction of the total power controlled. A dynamic power flow controller controls both the real and the reactive power flow between two AC sources having the same frequency. A dynamic power flow controller inserts a voltage with controllable magnitude and phase between two AC sources; thereby effecting control of active and reactive power flows between two AC sources.

  13. Neutral-point voltage control for a three-level DC-AC inverter using equivalent-input-disturbance approach

    Institute of Scientific and Technical Information of China (English)

    Jie ZHANG; Ryuichi YOKOYAMA; Jinhua SHE; Win WU

    2013-01-01

      One problem with a single source three-level inverter is the drafting of its neutral-point voltage. This may occur during transition or when unbalanced loads are connected to the inverter system. Variation of neutral-point voltage may greatly deteriorate the power quality. In this paper, we employ an equivalent-input-disturbance approach to deal with this problem. By adding an extra neutral leg, the control problem of neutral-point voltage is converted to a disturbance rejection problem. This method suppresses the variation of the neutral-point voltage to a low level and reduces the capacity of DC-link capacitors. Simulation results show the effectiveness of the method.

  14. Application of Load Compensation in Voltage Controllers of Large Generators in the Polish Power Grid

    Directory of Open Access Journals (Sweden)

    Bogdan Sobczak

    2014-03-01

    Full Text Available The Automatic Voltage Regulator normally controls the generator stator terminal voltage. Load compensation is used to control the voltage which is representative of the voltage at a point either within or external to the generator. In the Polish Power Grid (PPG compensation is ready to use in every AVR of a large generator, but it is utilized only in the case of generators operating at the same medium voltage buses. It is similar as in most European Power Grids. The compensator regulating the voltage at a point beyond the machine terminals has significant advantages in comparison to the slower secondary Voltage and Reactive Power Control System (ARNE1. The compensation stiffens the EHV grid, which leads to improved voltage quality in the distribution grid. This effect may be particularly important in the context of the dynamic development of wind and solar energy.

  15. Phosphor-in-glass for high-powered remote-type white AC-LED.

    Science.gov (United States)

    Lin, Hang; Wang, Bo; Xu, Ju; Zhang, Rui; Chen, Hui; Yu, Yunlong; Wang, Yuansheng

    2014-12-10

    The high-powered alternating current (AC) light-emitting diode (LED) (AC-LED), featuring low cost, high energy utilization efficiency, and long service life, will become a new economic growth point in the field of semiconductor lighting. However, flicker of AC-LED in the AC cycles is not healthy for human eyes, and therefore need to be restrained. Herein we report an innovation of persistent "phosphor-in-glass" (PiG) for the remote-type AC-LED, whose afterglow can be efficiently activated by the blue light. It is experimentally demonstrated that the afterglow decay of PiG in the microsecond range can partly compensate the AC time gap. Moreover, the substitution of inorganic glass for organic resins or silicones as the encapsulants would bring out several technological benefits to AC-LED, such as good heat-dissipation, low glare, and excellent physical/chemical stability.

  16. Voltage regulator for battery power source. [using a bipolar transistor

    Science.gov (United States)

    Black, J. M. (Inventor)

    1979-01-01

    A bipolar transistor in series with the battery as the control element also in series with a zener diode and a resistor is used to maintain a predetermined voltage until the battery voltage decays to very nearly the predetermined voltage. A field effect transistor between the base of the bipolar transistor and a junction between the zener diode and resistor regulates base current of the bipolar transistor, thereby regulating the conductivity of the bipolar transistor for control of the output voltage.

  17. Cost based reactive power participation for voltage control in multi units based isolated hybrid power system

    Directory of Open Access Journals (Sweden)

    Nitin Kumar Saxena

    2016-12-01

    Full Text Available Multi units of wind and diesel based generators in isolated hybrid power system have technical and operational advantages over single units system. They require dynamic reactive power compensation for fast recovery of voltage under load and input changes. In developing countries like India, investors’ prime concern is to provide continuous electricity at low rate while quality degradation can be permitted within pre defined acceptable range. The use of static compensator along with dynamic compensator may give cost effective reactive power participation for system. This paper presented pricing of reactive power compensation under steady state and transient conditions of system with fixed capacitor and STATCOM. The main contributions of the paper are; (i evaluating reactive power balance equation for generalized multi units of wind and diesel based isolated hybrid power system, (ii reactive power compensation using fixed capacitor and STATCOM in presence of composite load model, (ii fast recovery of voltage response using genetic algorithm based tuning of STATCOM controller, (iii evaluation of reactive power compensation cost for steady and dynamic conditions due to probabilistic change in load and/or input demand and (iv comparison of results with existing reference compensation method.

  18. KEY COMPARISON Final report on APMP international comparison APMP.EM-K9: High voltage AC-DC transfer standards

    Science.gov (United States)

    Wei, Yih-Cheng; Yeh, Hsin-Da

    2010-01-01

    The international key comparison APMP.EM-K9 of AC-DC high voltage transfer standards with 12 participants was carried out from June 2000 to January 2004. This comparison offers the same range and frequencies as BIPM key comparison CCEM-K9, voltages at 500 V and 1000 V, frequency from 1 kHz to 100 kHz. This comparison provides the national metrology institutes (NMIs) of the APMP member economies with an opportunity to link the values of their standards for AC-DC transfer difference to the international reference values. The results of the majority of the participating NMIs show an agreement with the reference value within the associated expanded uncertainty given by the individual NMI. The agreement of the results and the tables of the degree of equivalence of the participants are included. The results have been linked to the key comparison CCEM-K9. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

  19. Influence of metallic trays on the ac resistance and ampacity of low-voltage cables under non-sinusoidal currents

    Energy Technology Data Exchange (ETDEWEB)

    Demoulias, Charis; Labridis, Dimitris P.; Dokopoulos, Petros; Gouramanis, Kostas [Aristotle University of Thessaloniki, Department of Electrical and Computer Engineering, Thessaloniki (Greece)

    2008-05-15

    This paper investigates the influence of metallic trays on the ac resistance of PVC insulated, low-voltage (0.6/1.0 kV) cables made according to CENELEC standard HD603. The investigation is made with a validated finite element model for the fundamental and higher harmonic frequencies. It is shown that the cable's effective resistance is affected significantly by the relative magnetic permeability and specific conductivity of the tray, while the tray's dimensions do not affect it. The orientation of the cable with respect to the tray also influences the ac resistance of the phase and neutral conductors. An ampacity derating factor is defined and calculated for various cable cross-sections and harmonic loads. The presence of a metallic tray is shown to cause an additional derating of cable's ampacity which is relatively significant at large cable cross-sections. Working examples demonstrate the application of the results in calculating the ampacity of low-voltage cables and in assessing the energy savings that will result from the use of active harmonic filters. (author)

  20. Active power control with undead-band voltage & frequency droop applied to a meshed DC grid test system

    DEFF Research Database (Denmark)

    Vrana, Til Kristian; Zeni, Lorenzo; Fosso, Olav Bjarte

    2012-01-01

    A new method for controlling active power in HVDC grids has been tested on the meshed CIGRE B4 DC grid test system. The control strategy is based on the recently proposed undead-band droop control, which combines DC voltage and AC frequency droop. It provides sufficient roomm for optimisation...... for both normal and disturbed operation. Its main features are flexibility, reliability due to distributed control, easy expandability of the system and minimisation of communication needs. The control technique has been tested and its effectiveness has been verified to demonstrate its suitability...

  1. Modelling and Simulation of the SVC for Power System Flow Studies: Electrical Network in voltage drop

    Directory of Open Access Journals (Sweden)

    Narimen Aouzellag LAHAÇANI

    2008-12-01

    Full Text Available The goal of any Flexible AC Transmission Systems (FACTS devices study is to measure their impact on the state of the electrical networks into which they are introduced. Their principal function is to improve the static and dynamic properties of the electrical networks and that by increasing the margins of static and dynamic stability and to allow the power transit to the thermal limits of the lines.To study this impact, it is necessary to establish the state of the network (bus voltages and angles, powers injected and forwarded in the lines before and after the introduction of FACTS devices. This brings to calculate the powers transit by using an iterative method such as Newton-Raphson. Undertaking a calculation without the introduction of FACTS devices followed by a calculation with the modifications induced by the integration of FACTS devices into the network, makes it possible to compare the results obtained in both cases and thus assess the interest of the use of devices FACTS.

  2. Wind Power Plant Voltage Control Optimization with Embedded Application of Wind Turbines and Statcom

    DEFF Research Database (Denmark)

    Wu, Qiuwei; Solanas, Jose Ignacio Busca; Zhao, Haoran

    2017-01-01

    Increasing wind power penetration and the size of wind power plants (WPPs) brings challenges to the operation and control of power systems. Most of WPPs are located far from load centers and the short circuit ratio at the point of common coupling (PCC) is low. The fluctuations of wind power...... will cause voltage variations. An optimal voltage control scheme for WPPs with STATCOMs is presented in the paper. It ensures that the voltages within the WPPs and at the high voltage side of the WPPs are within the limits and maximizes the dynamic Var reserve of the WPPs. Case studies were conducted...

  3. Power flow analysis for droop controlled LV hybrid AC-DC microgrids with virtual impedance

    DEFF Research Database (Denmark)

    Li, Chendan; Chaudhary, Sanjay; Vasquez, Juan Carlos

    2014-01-01

    The AC-DC hybrid microgrid is an effective form of utilizing different energy resources and the analysis of this system requires a proper power flow algorithm. This paper proposes a suitable power flow algorithm for LV hybrid AC-DC microgrid based on droop control and virtual impedance. Droop...... and virtual impedance concepts for AC network, DC network and interlinking converter are reviewed so as to model it in the power flow analysis. The validation of the algorithm is verified by comparing it with steady state results from detailed time domain simulation. The effectiveness of the proposed...

  4. Design and Analysis of a Slope Voltage Control for a DFIG Wind Power Plant

    DEFF Research Database (Denmark)

    Martínez, J.; Kjær, P. C.; Rodriguez, Pedro

    2012-01-01

    This paper addresses a detailed design of a wind power plant and turbine slope voltage control in the presence of communication delays for a wide short-circuit ratio range operation. The implemented voltage control scheme is based upon the secondary voltage control concept, which offers fast...

  5. Single phase AC-DC power factor corrected converter with high frequency isolation using buck converter

    Directory of Open Access Journals (Sweden)

    R. Ramesh,

    2014-03-01

    Full Text Available Single phase ac-dc converters having high frequency isolation are implemented in buck, boost, buck-boost configuration with improving the power quality in terms of reducing the harmonics of input current. The paperpropose the circuit configuration, control mechanism, and simulation result for the single phase ac-dc converter.

  6. GAPOD and GA DC-voltage regulator based UPFC supplementary cont roller for damping low frequency oscillations in Multi-machine power systems

    Directory of Open Access Journals (Sweden)

    Dakka. Obulesu, Dr. S.F. Kodad, Dr. B.V. Sankar Ram

    2013-08-01

    Full Text Available The Unified Power Flow Controller (UPFC is the most versatile device in the FACTS (Flexible AC Transmission Systems which has emerged to enhance power system stability spectrum and dynamic performance. This paper briefs the effectiveness of the proposed GAPOD and GA DC-voltage regulator which has been tested on a 3-Machine, 9-Bus power system in comparison with Particle swarm optimization based Multi-Stage Fuzzy (PSOMSF DC-voltage regulator. The non-linear time-domain simulation results show thatthe oscillations of synchronous machines could be quickly and effectively damped with proposed GAPOD and GA DC-voltage regulator. The construction and implementation of this controller is fairly easy, which can be useful in real world power system.

  7. Measurement of a power system nominal voltage, frequency and voltage flicker parameters

    Energy Technology Data Exchange (ETDEWEB)

    Alkandari, A.M. [College of Technological Studies, Electrical Engineering Technology Department, Shwiekh (Kuwait); Soliman, S.A. [Electrical Power and Machines Department, Misr University for Science and Technology, Cairo (Egypt)

    2009-09-15

    We present, in this paper, an approach for identifying the frequency and amplitude of voltage flicker signal that imposed on the nominal voltage signal, as well as the amplitude and frequency of the nominal signal itself. The proposed algorithm performs the estimation in two steps; in the first step the original voltage signal is shifted forward and backward by an integer number of sample, one sample in this paper. The new generated signals from such a shift together with the original one is used to estimate the amplitude of the original signal voltage that composed of the nominal voltage and flicker voltage. The average of this amplitude gives the amplitude of the nominal voltage; this amplitude is subtracted from the original identified signal amplitude to obtain the samples of the flicker voltage. In the second step, the argument of the signal is calculated by simply dividing the magnitude of signal sample with the estimated amplitude in the first step. Calculating the arccosine of the argument, the frequency of the nominal signal as well as the phase angle can be computing using the least error square estimation algorithm. Simulation examples are given within the text to show the features of the proposed approach. (author)

  8. A novel high voltage start up circuit for an integrated switched mode power supply

    Energy Technology Data Exchange (ETDEWEB)

    Hu Hao; Chen Xingbi, E-mail: huhao21@uestc.edu.c [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China)

    2010-09-15

    A novel high voltage start up circuit for providing an initial bias voltage to an integrated switched mode power supply (SMPS) is presented. An enhanced mode VDMOS transistor, the gate of which is biased by a floating p-island, is used to provide start up current and sustain high voltage. An NMOS transistor having a high source to ground breakdown voltage is included to extend the bias voltage range to the SMPS. Simulation results indicate that the high voltage start up circuit can start and restart as designed. The proposed structure is believed to be more energy saving and cost-effective compared with other solutions. (semiconductor devices)

  9. SEMICONDUCTOR DEVICES: A novel high voltage start up circuit for an integrated switched mode power supply

    Science.gov (United States)

    Hao, Hu; Xingbi, Chen

    2010-09-01

    A novel high voltage start up circuit for providing an initial bias voltage to an integrated switched mode power supply (SMPS) is presented. An enhanced mode VDMOS transistor, the gate of which is biased by a floating p-island, is used to provide start up current and sustain high voltage. An NMOS transistor having a high source to ground breakdown voltage is included to extend the bias voltage range to the SMPS. Simulation results indicate that the high voltage start up circuit can start and restart as designed. The proposed structure is believed to be more energy saving and cost-effective compared with other solutions.

  10. Effect of semiconductor-controlled voltage injection by UPFC and ULTC on power system stability

    Science.gov (United States)

    Alavian Mehr, Alireza

    Commercial availability of various power semiconductor switches indicates proliferation of power electronic based apparatus in utility power systems. Furthermore, existing power system apparatus, e.g. mechanical phase shifters and mechanical tap changing transformers, will be retrofitted to utilize higher switching speed of semiconductor switches. A group of these apparatus, i.e., unified power flow controller (UPFC), static phase shifter (SPS), under-load tap-changing (ULTC) transformer and static series capacitor (SSC), perform their respective functions by means of injecting series controlled voltages in power systems. This thesis demonstrates that fast series voltage injection, for dynamic power flow regulation, can result in voltage dynamics and even voltage instability. This indicates that fast voltage injection by means of power electronic based apparatus can couple voltage stability and angle stability phenomena. To investigate this coupling phenomena, the voltage dependency of the load must be adequately represented in the load model. The reported studies in this work are based on representing the load by a combination of static and dynamic loads. This thesis primarily investigates impacts of UPFC and semiconductor-controlled ULTC on voltage stability and angle stability phenomena. An eigen analysis approach is used for the studies. The eigen analysis results are validated by digital time-domain simulations using a transient stability software. Both the eigen analysis and the transient stability software tools are tailored to account for angle and voltage stability phenomena.

  11. Enhancement of Power Quality in Transmission Line Using Flexible Ac Transmission System Device U.P.F.C (Unified Power Flow Controller

    Directory of Open Access Journals (Sweden)

    B. Divya Lakshmi

    2014-04-01

    Full Text Available Present scenario states that power demand has been increased in a rapid and random manner. Hence power generated is unable to meet the power demand so power scarcity exists. There is an approximate loss of (20 - 40 % of power generated during its transmission. Hence there is a need for enhancing the power quality in transmission lines. In order to improve the power quality our paper make use of FACTS DEVICES. FACTS devices can be added to power transmission and distribution systems at appropriate locations to improve system performance. The real and reactive powers can be easily controlled in a power system with FACTS devices. Flexible AC Transmission System creates a tremendous quality impact on power system stability. This paper describes the basic principle of operation of UPFC, its advantages and to compare its performance with the various FACTS equipment available. The objective of this paper is to keep the power system to remain in voltage stable condition when it experiences a load change and contingency, also deals with the simulation of various FACTS controllers using simulation program with MATLAB/SIMULINK

  12. A Study on Collaborative Operation Method for a New Energy Type Dispersed Power Supply System by AC-EMAP Model

    Science.gov (United States)

    Hidese, Koichi; Takano, Ichiro; Nishikawa, Hisao; Sawada, Yoshio

    Application of a dispersed power supply system combined with a large scale photovoltaic system (PV), a fuel cell (FC) and an electric double layer capacitor (EDLC) is studied in this paper. This system is operated in autonomous mode, taking account of time delay characteristics of FC. The modified Euler type Moving Average Prediction (EMAP) model is improved using short time fast fourier transform (ST-FFT). The Adaptive Control type EMAP (AC-EMAP) model is introduced to reduce the capacity of EDLC. This system can meet the multi-quality electric power requirements of customers, and compensate voltage stability and uninterruptible power supply (UPS) function as well. Moreover, the required capacity of EDLC to compensate the fluctuation of both PV output and load demand is clarified by the simulation based on collaborative operation method by a prediction model using software MATLAB/Simulink.

  13. Study on Optimization Strategy for Voltage and Reactive Power Control of Wind Farm

    Science.gov (United States)

    Lu, Q.; Shi, L.; Chen, N.

    A method for calculating reactive power limit of wind farm comprised of doubly-fed induction generators (DFIG) is proposed. The reactive power limit of wind farm is the sum of reactive power limit of DFIGs which is calculated by the method considering static stability margin. Based on this, reactive power control of wind farm is discussed and proposed. The proposed reactive power control is divided into different control modes according to power factor of high voltage side in wind farm substation and voltage of low voltage side in point of interconnection(POI). In different control modes, different control objects are applied on reactive power regulation. After reactive power regulation is finished, some reactive power of wind farm should be released. At last, numerical test system is established, the result shows that the proposed method is effective to support voltage of POI

  14. Reliability Evaluation of Power System Considering Voltage Stability and Continuation Power Flow

    Directory of Open Access Journals (Sweden)

    R. K. Saket

    2007-06-01

    Full Text Available This article describes the methodology for evaluation of the reliability of an composite electrical power system considering voltage stability and continuation power flow, which takes into account the peak load and steady state stability limit. The voltage stability is obtained for the probable outage of transmission lines and removal of generators along with the combined state probabilities. The loss of load probabilities (LOLP index is evaluated by merging the capacity probability with load model. State space is truncated by assuming the limits on total numbers of outages of generators and transmission lines. A prediction correction technique has been used along with one dimensional search method to get optimized stability limit for each outage states. The algorithm has been implemented on a six-bus test system.

  15. MODES OF OPERATION OF THE SYSTEM OF TRACTION POWER AC USING REACTIVE POWER COMPENSATION DEVICES

    Directory of Open Access Journals (Sweden)

    I.V. Domanskyi

    2015-06-01

    Full Text Available The paper presents a systematic analysis of existing methods of reactive power compensation. The study of operating modes of the systems external and traction power supply is carried out. The methodology for selecting promising compensation schemes and energy-saving in the traction networks AC electrified railway lines is offered. The comparative evaluation of prospective controlled compensation devices shows that use of seamlessly adjustable devices with unregulated condensing the battery and with parallel translator regulated with thyristor unit and with filters to reduce harmonics bond to the large capital investments. For traction networks of domestic railways payback period is more than 10-15 years. The most promising for traction power supply today is a stepwise adjustable devices of reactive power compensation. For the efficient allocation of investments in programs and projects of modernization of system traction power supply developed by the methodology of selecting parameters and places placement devices transverse compensation in the system traction power supply, which is based on the use of software systems with imitation of interconnected instant circuits moving loads of electric rolling stock. Based on the results of multiple calculations full factor experiment when simulating work of the systems traction power supply during the day marked the most influencing factors on energy-saving in process freight on electric traction and established the extent of their influence. These include the overflows of power, the resistance of traction network, reactive power compensation, power supply circuits and the organization of trains. Innovative technologies energy-saving railways from positions of consideration their close connection with the systems external power supply are proposed.

  16. Spin Backflow and ac Voltage Generation by Spin Pumping and the Inverse Spin Hall Effect

    NARCIS (Netherlands)

    Jiao, H.; Bauer, G.E.W.

    2013-01-01

    The spin current pumped by a precessing ferromagnet into an adjacent normal metal has a constant polarization component parallel to the precession axis and a rotating one normal to the magnetization. The former is now routinely detected as a dc voltage induced by the inverse spin Hall effect (ISHE).

  17. Breakdown Characteristic Analysis of Paper- Oil Insulation under AC and DC Voltage

    Science.gov (United States)

    Anuar, N. F.; Jamail, N. A. M.; Rahman, R. A.; Kamarudin, M. S.

    2017-08-01

    This paper presents the study of breakdown characteristic of Kraft paper insulated with two different types of insulating fluid, which are Palm oil and Coconut oil. Palm oil and Coconut oil are chosen as the alternative fluid to the transformer oil because it has high potential and environmentally-friendly. The Segezha Kraft papers with various thicknesses (65.5 gsm, 75 gsm, 85gsm, 90 gsm) have been used in this research. High Voltage Direct Current (HVDC), High Voltage Alternating Current (HVAC) and carbon track and severity analysis is conducted to observe the sample of aging Kraft paper. These samples have been immersed using Palm oil and Coconut oil up to 90 days to observe the absorption rate. All samples started to reach saturation level at 70 days of immersion. HVDC and HVAC breakdown experiments have been done after the samples had reached the saturation level based on normal condition, immersed in Palm oil and immersed in Coconut oil. All samples immersed in liquid show different breakdown voltage reading compared to normal condition. The analysis of carbon track and severity on surface has been done using Analytical Scanning Electron Microscope (SEM) Analysis. The results of the experiment show that the sample of Kraft paper immersed in Palm oil was better than Coconut oil immersed sample. Therefore the sample condition was the main factor that determines the value of breakdown voltage test. Introduction

  18. An algorithm for reduction of extracted power from photovoltaic strings in grid-tied photovoltaic power plants during voltage sags

    DEFF Research Database (Denmark)

    Tafti, Hossein Dehghani; Maswood, Ali Iftekhar; Pou, Josep

    2016-01-01

    Due to the high penetration of the installed distributed generation units in the power system, the injection of reactive power is required for the medium-scale and large-scale grid-connected photovoltaic power plants (PVPPs). Because of the current limitation of the grid-connected inverter......, the injected active power should be reduced during voltage sags. In order to obtain a constant dc-link voltage in a multi-string PVPP, the extracted power from PV strings should be equal to the injected power to the grid in all operating conditions (excluding power losses). Therefore, the extracted power of PV...

  19. Mini-Scale Power Distribution Network Feeding Trapezoidal-Wave Voltages to Power Electronic Loads with Diode Rectifiers

    Science.gov (United States)

    Noguchi, Toshihiko; Imoto, Masaru; Sato, Yoshikazu

    This paper proposes a novel three-phase power distribution system feeding trapezoidal voltages to various power electronic loads with diode rectifier front-ends. The network distributes trapezoidal voltages generated by synchronous superposition of wave-shaping voltages onto sinusoidal voltages available from a utility power grid. The power distribution by the trapezoidal voltages allows reducing harmonics of the line currents without electronic switching devices because of a spontaneously widened conduction period of the current waveforms. The reduction of the harmonic currents also contributes to improve total power factor at the load input terminals and efficiency of the power transmission cables. Since the diodes of the rectifiers successively commutate the trapezoidal waves during periods of their flat parts, not only total harmonic distortion of the currents is improved, but also voltage ripple across the dc-buses of the rectifiers can effectively be reduced with less filter capacitors. In addition, the system offers an uninterruptible power supply function by immediately changing its outputs from the wave-shaping voltages to the trapezoidal voltages when interruption occurs in the power grid. In this paper, a prototype of the system is experimentally examined from various angles of operating characteristics and test results are presented to prove feasibility of the proposed system.

  20. High-frequency high-voltage high-power DC-to-DC converters

    Science.gov (United States)

    Wilson, T. G.; Owen, H. A.; Wilson, P. M.

    1982-01-01

    A simple analysis of the current and voltage waveshapes associated with the power transistor and the power diode in an example current-or-voltage step-up (buck-boost) converter is presented. The purpose of the analysis is to provide an overview of the problems and design trade-offs which must be addressed as high-power high-voltage converters are operated at switching frequencies in the range of 100 kHz and beyond. Although the analysis focuses on the current-or-voltage step-up converter as the vehicle for discussion, the basic principles presented are applicable to other converter topologies as well.

  1. 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

  2. Multi-Stage Optimization Based Automatic Voltage Control Systems Considering Wind Power Forecasting Errors

    DEFF Research Database (Denmark)

    Qin, Nan; Bak, Claus Leth; Abildgaard, Hans

    2017-01-01

    cost and the generator reactive power output cost. The problem is formulated in a multi-stage optimal reactive power flow (MORPF) framework, solved by the nonlinear programming techniques via a rolling process. The voltage uncertainty caused by wind power forecasting errors is considered in the optimal......This paper proposes an automatic voltage control (AVC) system for power systems with limited continuous voltage control capability. The objective is to minimize the operational cost over a period, which consists of the power loss in the grid, the shunt switching cost, the transformer tap change...

  3. Stability Analysis of DC-link Voltage Control on Autonomous Micro Hydro Power Plant System

    OpenAIRE

    Feri Yusivar; M. Shanizal; A. Subiantoro; Gunawan, R

    2014-01-01

    Micro Hydro Power Plant has become one of the interesting topics to be researched nowadays. This paper deals with the stability analysis on control system of excitation voltage in Micro Hydro Power Plant. The control of this voltage can be achieved by controlling the Permanent Magnet Synchronous Machine (PMSM) with particular algorithm so the voltage on the DC-link part of the system can be controlled. Without knowing the exact specification of system parameters, the system will be most likel...

  4. Mathematical model for the power supply system of an autonomous object with an AC power transmission over a cable rope

    Science.gov (United States)

    Rulevskiy, V. M.; Bukreev, V. G.; Shandarova, E. B.; Kuleshova, E. O.; Shandarov, S. M.; Vasilyeva, Yu Z.

    2017-02-01

    A modeling problem of the power system, which provides an AC power transmission to a submersible device over the conducting rope, was considered. The power supply system units and their parameters are described. The system multi-dimensional mathematical model in the variables state space with regard to the nonlinear characteristic of system elements is proposed.

  5. Analog IC techniques for low-voltage low-power electronics

    NARCIS (Netherlands)

    Serdijn, W.A.; Verhoeven, C.J.M.; Van Roermund, A.H.M.

    1995-01-01

    Analog IC Techniques lor Low-Voltage Low Power Electronics addresses many very important, but recent, techniques which enable electronics to operate at a low supply voltage and consume a minimum amount of power. Apart from investigations at the device, circuit and system levels, the book provides a

  6. A new application area for fullerenes: voltage stabilizers for power cable insulation.

    Science.gov (United States)

    Jarvid, Markus; Johansson, Anette; Kroon, Renee; Bjuggren, Jonas M; Wutzel, Harald; Englund, Villgot; Gubanski, Stanislaw; Andersson, Mats R; Müller, Christian

    2015-02-01

    Fullerenes are shown to be efficient voltage-stabilizers for polyethylene, i.e., additives that increase the dielectric strength of the insulation material. Such compounds are highly sought-after because their use in power-cable insulation may considerably enhance the transmission efficiency of tomorrow's power grids. On a molal basis, fullerenes are the most efficient voltage stabilizers reported to date.

  7. Supervisory hybrid model predictive control for voltage stability of power networks

    NARCIS (Netherlands)

    Negenborn, R.R.; Beccuti, A.G.; Demiray, T.; Leirens, S.; Damm, G.; De Schutter, B.; Morari, M.

    2007-01-01

    Emergency voltage control problems in electric power networks have stimulated the interest for the implementation of online optimal control techniques. Briefly stated, voltage instability stems from the attempt of load dynamics to restore power consumption beyond the capability of the transmission a

  8. Analog IC techniques for low-voltage low-power electronics

    NARCIS (Netherlands)

    Serdijn, W.A.; Verhoeven, C.J.M.; Van Roermund, A.H.M.

    1995-01-01

    Analog IC Techniques lor Low-Voltage Low Power Electronics addresses many very important, but recent, techniques which enable electronics to operate at a low supply voltage and consume a minimum amount of power. Apart from investigations at the device, circuit and system levels, the book provides a

  9. Guidelines for Distribution System Operators on Reactive Power Provision by Electric Vehicles in Low Voltage Grids

    DEFF Research Database (Denmark)

    Zecchino, Antonio; Marinelli, Mattia; Træholt, Chresten

    2017-01-01

    The increasing success of electric vehicles is bringing new technical challenges to power system operators. This work intends to provide guidelines for distribution system operators in terms of reactive power requirements when evaluating and authorizing electric vehicles supply equipment with fast...... the amount of reactive power that an individual electric vehicle is expected to provide when connected to a low voltage feeder, in order to benefit of the desired voltage rise effect in comparison to the case of unitary power factor....

  10. Transmission Power Control using Small-Capacity UPFC under Output Voltage Saturation

    Science.gov (United States)

    Kuroda, Takeshi; Takeshita, Takaharu; Fujita, Hideki

    This paper presents a fast transmission power control scheme using a UPFC (Unified Power Flow Controller) under the output voltage saturation. For practical use of the UPFC, the fast and stable power response and the reduced power converter capacity are desired. The authors propose the fast and stable control scheme under the output voltage saturation of the reduced capacity UPFC. The effectiveness of the proposed control algorithm of the UPFC has been verified by experiments.

  11. A Stochastic Response Surface Method for Probabilistic Evaluation of the Voltage Stability Considering Wind Power

    Institute of Scientific and Technical Information of China (English)

    BAO Haibo; WEI Hua

    2012-01-01

    The traditional voltage stability analysis method is mostly based on the deterministic model, and ignores the uncertainties of bus loads, power supplies, changes in network configuration and so on. However, the great expansion of renewable power generations such as wind and solar energy in a power system has increased their uncertainty, and traditional techniques are limited in capturing their variable behavior. This leads to greater needs of new techniques and methodologies to properly quantify the voltage stability of power systems.

  12. An Integrated Chip High-Voltage Power Receiver for Wireless Biomedical Implants

    Directory of Open Access Journals (Sweden)

    Vijith Vijayakumaran Nair

    2015-06-01

    Full Text Available In near-field wireless-powered biomedical implants, the receiver voltage largely overrides the compliance of low-voltage power receiver systems. To limit the induced voltage, generally, low-voltage topologies utilize limiter circuits, voltage clippers or shunt regulators, which are power-inefficient methods. In order to overcome the voltage limitation and improve power efficiency, we propose an integrated chip high-voltage power receiver based on the step down approach. The topology accommodates voltages as high as 30 V and comprises a high-voltage semi-active rectifier, a voltage reference generator and a series regulator. Further, a battery management circuit that enables safe and reliable implant battery charging based on analog control is proposed and realized. The power receiver is fabricated in 0.35-μm high-voltage Bipolar-CMOS-DMOStechnology based on the LOCOS0.35-μm CMOS process. Measurement results indicate 83.5% power conversion efficiency for a rectifier at 2.1 mA load current. The low drop-out regulator based on the current buffer compensation and buffer impedance attenuation scheme operates with low quiescent current, reduces the power consumption and provides good stability. The topology also provides good power supply rejection, which is adequate for the design application. Measurement results indicate regulator output of 4 ± 0.03 V for input from 5 to 30 V and 10 ± 0.05 V output for input from 11 to 30 V with load current 0.01–100 mA. The charger circuit manages the charging of the Li-ion battery through all if the typical stages of the Li-ion battery charging profile.

  13. Investigation of surface modifications in ethylene propylene diene monomer (EPDM) rubber due to tracking under a.c. and d.c. voltages

    Indian Academy of Sciences (India)

    R Sarathi; Uma Maheswar Rao

    2001-12-01

    In the present work, tracking phenomena has been studied with the ethylene propylene diene monomer (EPDM) material under the a.c. and d.c. voltages, with ammonium chloride/acid rain solution as the contaminant. It is noticed that the tracking time depends on the conductivity and flow rate of the contaminant. The physico-chemical analyses viz. wide angle X-ray diffraction (WAXD), thermo-gravimetric differential thermal analysis (TG-DTA) and the differential scanning calorimetry (DSC) studies, were carried out and it was concluded that the tracking process is a surface degradation process. The tracking time is different for a.c. and d.c. voltages.

  14. Reactive Power Strategy of Cascaded Delta-connected STATCOM Under Asymmetrical Voltage Conditions

    DEFF Research Database (Denmark)

    He, Zhixing; Ma, Fujun; Xu, Qianming;

    2017-01-01

    Cascaded static synchronous compensator (STATCOM) is an effective solution for reactive power support in mid-dle/high voltage conditions, and it has been widely employed to control reactive power in photovoltaic (PV) plants, wind farms, and industrial occasions. In this paper, reactive power...... control strategy of cascaded delta-connected STATCOM under asym-metrical voltage conditions is investigated. A new phase current reference calculation method is proposed to support reactive power continually under abnormal voltage conditions considering cluster voltage balancing control and phase current...... of the phase current references. Furthermore, the reactive power support capability of cascaded STATCOM under asymmetrical voltage conditions is explored and compared by combining the proposed references calculation method with the three generalized current references calculation strategies. Finally...

  15. High voltage generator circuit with low power and high efficiency applied in EEPROM

    Institute of Scientific and Technical Information of China (English)

    Liu Yan; Zhang Shilin; Zhao Yiqiang

    2012-01-01

    This paper presents a low power and high efficiency high voltage generator circuit embedded in electrically erasable programmable read-only memory (EEPROM).The low power is minimized by a capacitance divider circuit and a regulator circuit using the controlling clock switch technique.The high efficiency is dependent on the zero threshold voltage (Vth) MOSFET and the charge transfer switch (CTS) charge pump.The proposed high voltage generator circuit has been implemented in a 0.35μm EEPROM CMOS process.Measured results show that the proposed high voltage generator circuit has a low power consumption of about 150.48 μW and a higher pumping efficiency (83.3%) than previously reported circuits.This high voltage generator circuit can also be widely used in low-power flash devices due to its high efficiency and low power dissipation.

  16. Comprehensive Reactive Power Support of DFIG Adapted to Different Depth of Voltage Sags

    Directory of Open Access Journals (Sweden)

    Yangwu Shen

    2017-06-01

    Full Text Available The low voltage ride-through (LVRT capability of the doubly-fed induction generator (DFIG significantly impacts upon the integration of wind power into the power grid. This paper develops a novel comprehensive control strategy to enhance the LVRT and reactive power support capacities of the DFIG by installing the energy storage system (ESS. The ESS is connected to the DC-link capacitor of the DFIG and used to regulate the DC-link voltage during normal or fault operations. The unbalanced power between the captured wind power and the power injected to the grid during the transient process is absorbed or compensated by the ESS. The rotor-side converter (RSC is used to control the maximum power production and the grid-side converter (GSC is used to control the reactive power before participating in the voltage support. When the supply voltage continues to drop, the rotor speed is increased by controlling the RSC to realize the LVRT capability and help the GSC further enhance the reactive power support capability. The capacity of the GSC is dedicated to injecting the reactive power to the grid. An auxiliary transient pitch angle controller is proposed to protect the generator’s over speed. Both RSC and GSC act as reactive power sources to further enhance the voltage support capability with serious voltage sags. Simulations based on a single-machine infinite-bus power system verify the effectiveness of the developed comprehensive control strategy.

  17. Analysis and simulation of the three-phase AC voltage regulation circuit%三相交流调压电路的分析与仿真

    Institute of Scientific and Technical Information of China (English)

    李衍孜

    2012-01-01

    Based on the analysis of the operation principle and mode of the single-phase AC voltage-regulation circuit, the voltage-regulating rule and effect of three-phase AC voltage-regulation was studied deeply in the paper. The theory of the three-phase star-style AC voltage-regulation circuit was tested in matlab/simulink, the simulation result proved the analysis of the theory of the three-phase AC voltage-regulation circuit was correct.%在分析单相交流调压电路运行原理和工作方式的基础上,深入研究了三相交流调压电路的调压规律和调压效果,并在Matlab/simulink仿真平台上对三相星形无中线交流调压电路的理论部分进行了验证,结果表明:三相交流调压电路的分析是正确的.

  18. Multi-Agent-Based Controller for Voltage Enhancement in AC/DC Hybrid Microgrid Using Energy Storages

    Directory of Open Access Journals (Sweden)

    Ahmadali Khatibzadeh

    2017-02-01

    Full Text Available Development of renewable energies and DC loads have led microgrids toward the creation of DC networks. The predictions show that the hybrid microgrids will be used widely in the future. This article has studied the voltage stability in the presence of sources of energy storage in AC/DC hybrid networks. However, because the different dynamics of hybrid networks applying centralized and distributed controllers will be faced with different problems, in this study, a multi-agent control for the microgrid has been used. A new structure referred to here as an event-driven microgrid control management (EDMCM has been developed to control the microgrid. This method increases response speed and accuracy of decision making. Hybrid Network Simulation results confirm the validity of the developed model.

  19. SURVEY ON DISTRIBUTED GENERATION BASED DIFFERENT MULTILEVEL DC-AC POWER INVERTER FOR HARMONIC REDUCTION

    OpenAIRE

    Meera, V.

    2017-01-01

    Multilevel inverter has been under research and development for more than three decades and has found successful industrial application. Also, it has become the enabling power conversion technology for high voltage and high power applications in present power systems and large electric motor drives. The propagated energy source consists of solar cells, wind turbines, micro-turbines (natural gas), fuel cells and storage batteries and also connected to the low voltage distribution network throu...

  20. Fuzzy Controller for a Voltage-Regulated Solar-Powered MPPT System for Hybrid Power System Applications

    Directory of Open Access Journals (Sweden)

    Jaw-Kuen Shiau

    2015-04-01

    Full Text Available This paper presents the design of a fuzzy-logic-based voltage-regulated solar power maximum power point tracking (MPPT system for applications involving hybrid power systems. The system contains a solar power system and battery as the primary and secondary power sources, respectively. The solar system alone supplies power to the electric motor and maintains the output voltage at a predetermined level when it has sufficient power. When the solar power is insufficient, the solar system is operated at its maximum power point (MPP and the battery is engaged to compensate for the insufficiency. First, a variant of the incremental conductance MPP condition was established. Under the MPP condition, the voltage-regulated MPPT system was formulated as a feedback control system, where the MPP condition and voltage regulation requirements were used as the system inputs. Next, a fuzzy controller was developed to perform the voltage-regulated MPPT function for the hybrid power system. A simulation model based on Matrix laboratory (MATLAB/SIMULINK (a block diagram environment for multi-domain simulation and model-based design and a piecewise linear electric circuit simulation (PLECS tool for controlling the dc motor velocity was developed to verify the voltage-regulated solar power MPPT system.

  1. Improved Design Methods for Robust Single- and Three-Phase ac-dc-ac Power Converters

    DEFF Research Database (Denmark)

    Qin, Zian

    becomes a emerging challenge. Accordingly, installation of sustainable power generators like wind turbines and solar panels has experienced a large increase during the last decades. Meanwhile, power electronics converters, as interfaces in electrical system, are delivering approximately 80 % electricity...

  2. Efficient Lightweight AC-AC Power Control for Solar UAV Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A highly efficient and lightweight dual bridge matrix power controller development is proposed that will provide high performance to a solar powered high altitude...

  3. KEY COMPARISONS: Final report: SIM regional comparison of ac-dc voltage transfer difference (SIM.EM.K6a, SIM.EM-K9 and SIM.EM-K11)

    Science.gov (United States)

    Campos, Sara; Filipski, Piotr; Izquierdo, Daniel; Afonso, Edson; Landim, Régis P.; Di Lillo, Lucas; Lipe, Thomas

    2009-01-01

    Three comparisons of ac-dc voltage transfer difference held from January to December 2004 are reported. Six NMIs in the SIM region took part: NRC (Canada), NIST (United States of America), CENAM (Mexico), INTI (Argentina), UTE (Uruguay) and INMETRO (Brazil). The comparisons were proposed to assess the measurement capabilities in ac-dc voltage transfer difference of the NMIs in the SIM region. The test points were selected to link the results with the equivalent CCEM Key Comparisons, through three NMIs participating in both SIM and CCEM key comparisons. Additionally, a SIM.EM-Supplementary comparison was proposed, in support of the SIM NMIs' power/energy meter calibration capabilities. One technical protocol and one travelling standard were used, to economize on time and resources. The report shows the degree of equivalence in the SIM region and also the degree of equivalence with the corresponding CCEM reference value. The results of all participants support the values and uncertainties of the applicable CMC entries for ac-dc voltage transfer difference in the Key Comparison Database held at the BIPM. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

  4. A Sufficient Condition on Convex Relaxation of AC Optimal Power Flow in Distribution Networks

    DEFF Research Database (Denmark)

    Huang, Shaojun; Wu, Qiuwei; Wang, Jianhui;

    2016-01-01

    This paper proposes a sufficient condition for the convex relaxation of AC Optimal Power Flow (OPF) in radial distribution networks as a second order cone program (SOCP) to be exact. The condition requires that the allowed reverse power flow is only reactive or active, or none. Under the proposed...... sufficient condition, the feasible sub-injection region (power injections of nodes excluding the root node) of the AC OPF is convex. The exactness of the convex relaxation under the proposed condition is proved through constructing a group of monotonic series with limits, which ensures that the optimal...... solution of the SOCP can be converted to an optimal solution of the original AC OPF. The efficacy of the convex relaxation to solve the AC OPF is demonstrated by case studies of an optimal multi-period planning problem of electric vehicles (EVs) in distribution networks....

  5. A Sufficient Condition on Convex Relaxation of AC Optimal Power Flow in Distribution Networks

    DEFF Research Database (Denmark)

    Huang, Shaojun; Wu, Qiuwei; Wang, Jianhui

    2016-01-01

    This paper proposes a sufficient condition for the convex relaxation of AC Optimal Power Flow (OPF) in radial distribution networks as a second order cone program (SOCP) to be exact. The condition requires that the allowed reverse power flow is only reactive or active, or none. Under the proposed...... sufficient condition, the feasible sub-injection region (power injections of nodes excluding the root node) of the AC OPF is convex. The exactness of the convex relaxation under the proposed condition is proved through constructing a group of monotonic series with limits, which ensures that the optimal...... solution of the SOCP can be converted to an optimal solution of the original AC OPF. The efficacy of the convex relaxation to solve the AC OPF is demonstrated by case studies of an optimal multi-period planning problem of electric vehicles (EVs) in distribution networks....

  6. Intelligent energy harvesting scheme for microbial fuel cells: Maximum power point tracking and voltage overshoot avoidance

    Science.gov (United States)

    Alaraj, Muhannad; Radenkovic, Miloje; Park, Jae-Do

    2017-02-01

    Microbial fuel cells (MFCs) are renewable and sustainable energy sources that can be used for various applications. The MFC output power depends on its biochemical conditions as well as the terminal operating points in terms of output voltage and current. There exists one operating point that gives the maximum possible power from the MFC, maximum power point (MPP), for a given operating condition. However, this MPP may vary and needs to be tracked in order to maintain the maximum power extraction from the MFC. Furthermore, MFC reactors often develop voltage overshoots that cause drastic drops in the terminal voltage, current, and the output power. When the voltage overshoot happens, an additional control measure is necessary as conventional MPPT algorithms will fail because of the change in the voltage-current relationship. In this paper, the extremum seeking (ES) algorithm was used to track the varying MPP and a voltage overshoot avoidance (VOA) algorithm is developed to manage the voltage overshoot conditions. The proposed ES-MPPT with VOA algorithm was able to extract 197.2 mJ during 10-min operation avoiding voltage overshoot, while the ES MPPT-only scheme stopped harvesting after only 18.75 mJ because of the voltage overshoot happened at 0.4 min.

  7. Impact of distributed generators on the power loss and voltage profile of sub-transmission network

    Directory of Open Access Journals (Sweden)

    A.S.O. Ogunjuyigbe

    2016-05-01

    Full Text Available This paper presents the impact of distributed generator (DG on the power loss and voltage profile of sub-transmission network at different penetration levels (PLs. The various DG technologies are modeled based on their electrical output characteristics. Voltage profile index which allows a single value to represent how well the voltage matches the ideal value is developed. The index allows a fair comparison of the voltage profile obtained from different scenarios. The extent to which DGs affect power losses and voltage profile depend on the type of DG technology, PL and the location in which the DG is connected to the grid. The integration of DGs reduces power losses on the network, however, as the PL increases, the power losses begin to increase. A PL of 50–75% is achieved on 69 kV voltage level and 25–50% penetration on 13.8 kV voltage level without an increase in the power loss. Also more DG can be integrated into the network at point of common connection of higher voltage level compared to the low voltage level.

  8. 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.

  9. 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)

  10. 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.

  11. Performance of Doubly-Fed Wind Power Generators During Voltage Dips

    DEFF Research Database (Denmark)

    Aparicio, N.; Chen, Zhe; Beltran, H.

    ) can regulate easily the reactive power generated in steady state. However, difficulties appear when reactive power has to be generated during voltage dips. Simulations have been carried out in order to check whether DFIG wind turbines can fulfill the reactive power requirements. Protection system......The growing of wind generation in Spain has forced its Transmission System Operator (TSO) to release new requirements that establish the amount of reactive power that a wind turbine has to supply to the grid during a voltage dip. Wind turbines equipped with doubly-fed induction generators (DFIG...... acting as STATCOM helps to improve the voltage profile sufficiently to permit rotor-side converter reconnection....

  12. Autonomous Active Power Control for Islanded AC Microgrids with Photovoltaic Generation and Energy Storage System

    DEFF Research Database (Denmark)

    Wu, Dan; Tang, Fen; Dragicevic, Tomislav;

    2014-01-01

    , an autonomous active power control strategy is proposed for AC islanded microgrids in order to achieve power management in a decentralized manner. The proposed control algorithm is based on frequency bus-signaling of ESS and uses only local measurements for power distribution among microgrid elements. Moreover......, this paper also presents a hierarchical control structure for AC microgrids that is able to integrate the ESS, PV systems and loads. Hereby, basic power management function is realized locally in primary level, while strict frequency regulation can be achieved by using additional secondary controller......In an islanded AC microgrid with distributed energy storage system (ESS), photovoltaic (PV) generation and loads, a coordinated active power regulation is required to ensure efficient utilization of renewable energy, while keeping the ESS from overcharge and over discharge conditions. In this paper...

  13. Maximum Power Point Tracking of Photovoltaic power Generation System Based on Fuzzy Approximation of Operating Point Voltage with Radiation Intensity

    Directory of Open Access Journals (Sweden)

    H. Ijadi

    2012-09-01

    Full Text Available In this paper, a method to track the maximum power of solar panels based on fuzzy logic is presented. The proposed method is based on the relationship between radiation intensity and the voltage of maximum power operating point. With this relationship, at any time by measuring the light intensity, voltage can be calculated at the maximum power point by using fuzzy approximation function. In order to verify the proposed method, simulation results are presented.

  14. Secondary control for reactive power sharing and voltage amplitude restoration in droop-controlled islanded microgrids

    DEFF Research Database (Denmark)

    Micallef, A.; Apap, M.; Spiteri Staines, C.

    2012-01-01

    This paper focuses on the islanded operation of microgrids. In this mode of operation, the microsources are required to cooperate autonomously to regulate the local grid voltage and frequency. Droop control is typically used to achieve this autonomous voltage and frequency regulation. However...... and to restore the voltage deviations caused by the droop control. Primary droop control loops where implemented in the inverters to supply the real and reactive power. Simulation results are presented showing the feasibility of the proposed algorithm in achieving reactive power sharing between the inverters...... connected to the microgrid while simultaneously restoring the voltage deviations due to the droop control....

  15. Investigation of Power Factor on Harmonic Effect due to Types of Voltage Source

    Directory of Open Access Journals (Sweden)

    C.B. Risnidar

    2011-01-01

    Full Text Available This paper discussed about power factor on harmonic effect due to types of voltage source. Usually, the voltage source is sinusoidal. But in actual condition the load that has voltage sources through the elements where the output voltage of element as input to load is not pure sinusoidal, for example at Power of Common Coupling (PCC between transformer and linear load and nonlinear load. The research has been done with Schhafner Power Quality Analyzer and was focused to power factor (p.f., Total Harmonic Distortion (THD, and harmonic energy losses cost from measurement where load is Induction motor and Adjustable Speed Drive (ASD. As voltage source in this research are sine wave, square wave and combinations of 3rd, 5th and 7th harmonic order like harmonic 313, and harmonic 357.

  16. Voltage regulation and reactive power supply capability of distributed generation : applications in active distribution systems

    Energy Technology Data Exchange (ETDEWEB)

    Katiraei, F.; Yazdani, A.; Uluski, R. [Quanta Technology, New York, NY (United States); Vaziri, M. [Pacific Gas and Electric Co., San Fransisco, CA (United States)

    2009-07-01

    Problems regarding voltage regulation on distribution feeders arise when there is a large demand for reactive power. The addition of distributed generation changes the power flow and voltage profile of a power system. The current practice is to use distributed generation passively and perform voltage regulation as before. However, this may not function well with high distributed generation penetration. This presentation discussed voltage regulation and the reactive power supply capability of distributed generation. Several applications in active distribution systems were presented. Specifically, the presentation discussed distributed interconnection challenges; utility practices and limiting factors; and the real and reactive power capabilities of distributed generation. A case study was also presented. It was concluded that in order for distributed generation to actively participate in real and reactive power management of distribution systems, a change is needed in standards and utility guidelines, along with a better understanding of distributed generation technologies and controls. 1 tab., 11 figs.

  17. Hybrid Voltage-Multipliers Based Switching Power Converters

    Science.gov (United States)

    Rosas-Caro, Julio C.; Mayo-Maldonado, Jonathan C.; Vazquez-Bautista, Rene Fabian; Valderrabano-Gonzalez, Antonio; Salas-Cabrera, Ruben; Valdez-Resendiz, Jesus Elias

    2011-08-01

    This work presents a derivation of PWM DC-DC hybrid converters by combining traditional converters with the Cockcroft-Walton voltage multiplier, the voltage multiplier of each converter is driven with the same transistor of the basic topology; this fact makes the structure of the new converters very simple and provides high-voltage gain. The traditional topologies discussed are the boost, buck-boost, Cuk and SEPIC. They main features of the discussed family are: (i) high-voltage gain without using extreme duty cycles or transformers, which allow high switching frequency and (ii) low voltage stress in switching devices, along with modular structures, and more output levels can be added without modifying the main circuit, which is highly desirable in some applications such as renewable energy generation systems. It is shown how a multiplier converter can become a generalized topology and how some of the traditional converters and several state-of-the-art converters can be derived from the generalized topologies and vice-versa. All the discussed converters were simulated, additionally experimental results are provided with an interleaved multiplier converter.

  18. Motor power control circuit for ac induction motors

    Science.gov (United States)

    Nola, F. J. (Inventor)

    1983-01-01

    A motor power control of the type which functions by controlling the power factor wherein one of the parameters of power factor current on time is determined by the on time of a triac through which current is supplied to the motor. By means of a positive feedback circuit, a wider range of control is effected.

  19. Overmodulation of n-level three-leg DC-AC diode-clamped converters with comprehensive capacitor voltage balance

    DEFF Research Database (Denmark)

    Busquets-Monge, S.; Maheshwari, Ram Krishan; Munk-Nielsen, Stig

    2013-01-01

    This paper presents a novel PWM strategy for nlevel three-leg semiconductor-clamped dc-ac converters in the overmodulation region, with dc-link capacitor voltage balance in every switching cycle. The strategy is based on the virtual-vector concept. Suitable reference vector trajectories are selec...

  20. Apparatus for Controlling Low Power Voltages in Space Based Processing Systems

    Science.gov (United States)

    Petrick, David J. (Inventor)

    2017-01-01

    A low power voltage control circuit for use in space missions includes a switching device coupled between an input voltage and an output voltage. The switching device includes a control input coupled to an enable signal, wherein the control input is configured to selectively turn the output voltage on or off based at least in part on the enable signal. A current monitoring circuit is coupled to the output voltage and configured to produce a trip signal, wherein the trip signal is active when a load current flowing through the switching device is determined to exceed a predetermined threshold and is inactive otherwise. The power voltage control circuit is constructed of space qualified components.

  1. Performance Evaluations of A Single Inductor Type Resonant AC Link Snubber-Assisted Three-Phase Voltage Source Soft-Switching Inverter

    National Research Council Canada - National Science Library

    Yoshida, Masanobu; Hiraki, Eiji; Nakaoka, Mutsuo

    2003-01-01

      This paper presents a novel three-phase voltage source type soft-switching inverter using the main and auxiliary IGBT power module packages in order to reduce their switching power losses as well...

  2. A Coordinated Control for Photovoltaic Generators and Energy Storages in Low-Voltage AC/DC Hybrid Microgrids under Islanded Mode

    DEFF Research Database (Denmark)

    Liu, Yao; Hou, Xiaochao; Wang, Xiaofeng;

    2016-01-01

    The increasing penetration of renewable generators can be a significant challenge due to the fluctuation of their power generation. Energy storage (ES) units are one solution to improve power supply quality and guarantee system stability. In this paper, a hybrid microgrid is built based...... on photovoltaic (PV) generator and ES; and coordinated control is proposed and developed to achieve power management in a decentralized manner. This control scheme contains three different droop strategies according to characteristics of PV and ES. First, the modified droop control is proposed for PV, which can...... for alternating current (AC)-side ES. Thus, the ES lifetime is prolonged. Moreover, interlinking converters (ICs) provide a bridge between AC/DC buses in a hybrid microgrid. The power control of IC is enabled when the AC- or DC-side suffer from active power demand shortage. In particular, if the AC microgrid does...

  3. The effect of reactive power generation modeling on voltage stability analysis

    Energy Technology Data Exchange (ETDEWEB)

    Tovar, E.; Guizar, J.G.C. [Inst. de Investigaciones Electricas, Cuernavaca, Morelos (Mexico)

    2010-08-13

    One of the most significant concerns for power system planning and operation in many countries involves problems related to voltage instability in electrical power systems. Blackouts have been caused by voltage instability problems throughout the world during the last few decades. Several factors can contribute to long term voltage instability problems, including high active and reactive loading, operation of on load tap changer transformers, inadequate locally available reactive power resources, load characteristics at low voltage magnitudes and operation of relay protection. There is a significant need to evaluate an index which gives the operating point proximity to voltage instability. This paper examined the influence of generator voltage dependent reactive power production on system voltage stability using the minimum singular value from the Jacobian Matrix of the load flow formulation. The synchronous generator model considered voltage reactive power limits due to maximum armature current, maximum and minimum field current as well as under excitation limiters. The generation model used in this paper was included in an ordinary load flow program, and resulted from studies of a representative 62 bus Norwest control area Mexican system, which included 19 generators. Specifically, the paper discussed the generator model with particular reference to the maximum field current limit; armature current limit; minimum field current limit; and underexcitation limit. The singular value decomposition and computational results were also presented. It was concluded that as the loading of the system increases, the reactive power produced by the machines also increases, and that reactive power is delivered when the induced voltage is greater than the terminal voltage. 15 refs., 3 tabs., 2 figs.

  4. A SCHEDULING SCHEME WITH DYNAMIC FREQUENCY CLOCKING AND MULTIPLE VOLTAGES FOR LOW POWER DESIGNS

    Institute of Scientific and Technical Information of China (English)

    Wen Dongxin; Wang Ling; Yang Xiaozong

    2007-01-01

    In this letter, a scheduling scheme based on Dynamic Frequency Clocking (DFC) and multiple voltages is proposed for low power designs under the timing and the resource constraints.Unlike the conventional methods at high level synthesis where only voltages of nodes were considered,the scheme based on a gain function considers both voltage and frequency simultaneously to reduce energy consumption. Experiments with a number of DSP benchmarks show that the proposed scheme achieves an effective energy reduction.

  5. Impact on Generator Reactive Power Limits on a Static Voltage Stability

    Directory of Open Access Journals (Sweden)

    TOVAR-GONZALEZ, E. A.

    2011-11-01

    Full Text Available Voltage stability margin in a power system is closely related with the availability of reactive power in the system. Therefore, adequate modeling of the reactive power sources becomes an important issue in this type of studies. The Minimum Singular Value of the load flow Jacobian matrix has been commonly used as a static voltage stability index. In this paper, such index is used to assess the influence on the static voltage stability limit of modeling the generators reactive power limits by its capability curve. Simulation results on a test system indicate that modeling the reactive power limits of the generating units by the simplified Qmin/Qmax approach, commonly used by most of the load flow programs, yields optimistic values for this voltage stability index.

  6. Voltage Control of Distribution Grids with Multi-Microgrids Using Reactive Power Management

    Directory of Open Access Journals (Sweden)

    WLODARCZYK, P.

    2015-02-01

    Full Text Available Low-voltage Microgrids can be valuable sources of ancillary services for the Distribution System Operators (DSOs. The aim of this paper was to study if and how multi-microgrids can contribute to Voltage Control (VC in medium-voltage distribution grids by means of reactive power generation and/or absorption. The hierarchical control strategy was proposed with the main focus on the tertiary control which was defined as optimal power flow problem. The interior-point algorithm was applied to optimise experimental benchmark grid with the presence of Distributed Energy Resources (DERs. Moreover, two primary objectives were formulated: active power losses and amount of reactive power used to reach the voltage profile. As a result the active power losses were minimised to the high extent achieving the savings around 22% during entire day.

  7. Management of Power Quality Issues in Low Voltage Networks using Electric Vehicles: Experimental Validation

    DEFF Research Database (Denmark)

    Martinenas, Sergejus; Knezovic, Katarina; Marinelli, Mattia

    2016-01-01

    As Electric Vehicles (EVs) are becoming more wide spread, their high power consumption presents challenges for the residential low voltage networks, especially when connected to long feeders with unevenly distributed loads. However, if intelligently integrated, EVs can also partially solve...... the existing and future power quality problems. One of the main aspects of the power quality relates to voltage quality. The aim of this work is to experimentally analyse whether series-produced EVs, adhering to contemporary standard and without relying on any V2G capability, can mitigate line voltage drops...

  8. Analysis and implementation of power management and control strategy for six-phase multilevel ac drive system in fault condition

    Directory of Open Access Journals (Sweden)

    Sanjeevikumar Padmanaban

    2016-03-01

    Full Text Available This research article exploits the power management algorithm in post-fault conditions for a six-phase (quad multilevel inverter. The drive circuit consists of four 2-level, three-phase voltage source inverter (VSI supplying a six-phase open-end windings motor or/impedance load, with circumstantial failure of one VSI investigated. A simplified level-shifted pulse-width modulation (PWM algorithm is developed to modulate each couple of three-phase VSI as 3-level output voltage generators in normal operation. The total power of the whole ac drive is shared equally among the four isolated DC sources. The developed post-fault algorithm is applied when there is a fault by one VSI and the load is fed from the remaining three healthy VSIs. In faulty conditions the multilevel outputs are reduced from 3-level to 2-level, but still the system propagates with degraded power. Numerical simulation modelling and experimental tests have been carried out with proposed post-fault control algorithm with three-phase open-end (asymmetrical induction motor/R-L impedance load. A complete set of simulation and experimental results provided in this paper shows close agreement with the developed theoretical background.

  9. PSO-Based Voltage Control Strategy for Loadability Enhancement in Smart Power Grids

    Directory of Open Access Journals (Sweden)

    Heng-Yi Su

    2016-12-01

    Full Text Available This paper proposes a new voltage control methodology using the particle swarm optimization (PSO technique for smart grid loadability enhancement. The goal of this paper is to achieve reliable and efficient voltage profile/stability regulation in power grids. This methodology is based on the decouple power flow equations and the worst-case design technique. Specifically, the secondary voltage control (SVC problem is formulated as an L-infinity norm minimization problem which considers overall load voltage deviations in electrical power systems as an objective model, and the PSO technique is employed to determine a robust control action which aims to improve voltage profile and to enlarge transmission grid loadability by optimal coordinated control of VAR sources. The methodology was successfully tested on several IEEE benchmark systems.

  10. Improvement and test of high power amplifier high voltage interlock circuit%高功放高压联锁电路改进与测试

    Institute of Scientific and Technical Information of China (English)

    金华松; 邱冬冬; 刘斯亮

    2012-01-01

    Whether the device can work regularly was determined by the performance of high voltage interlock directly. Through the operating principle analysis of high voltage interlock circuit and AC time delayer of high power amplifier based on CPI mechanical cabinet, an improved high voltage interlock circuit solution and a test method applied in AC time delayer are studied. The improved interlock circuit overcomes the drawbacks of original high voltage interlock solution. The designed test circuit can carry out quantitative test of AC time delayer parameters.%高压联锁性能的好坏直接影响设备能否正常工作.通过分析CPI高功放(HPA)的延时加高压程序、高压联锁电路和交流延时器工作原理,研究出一种新改选的高压联锁电路方案和用于交流延时器的测试方法.分析阐述表明,该方案和测试方法克服了CPI高功放的高压联锁方案的弊端.另外,根据分析结果设计了延时测试电路,它可对交流延时器性能参数进行定量测试.

  11. Proposal of indexes for fast voltage stability evaluation of ac/dc transmission systems

    Directory of Open Access Journals (Sweden)

    Jorge Wilson González

    2011-01-01

    Full Text Available En este artículo se desarrolla un análisis de estabilidad de tensión de sistemas ca/cd empleando indicadores estáticos y modales. Se propone un tratamiento novedoso para indicadores de estabilidad de tensión, con el fin de obtener una mayor información sobre los requerimientos en redes de variadas fortalezas, en términos de la estabilidad de tensión. El nuevo tratamiento se ofrece como un medio para prevenir potenciales problemas en redes de transmisión de corriente directa, High Voltage dc Transmission Systems (HVdc, conectados a nodos débiles. Los indicadores son convertidos a por unidad y comparados en diferentes relaciones de corto circuito, Short Circuit Ratios (SCR, en una red modificada tipo IEEE de 14 barras, la cual posee un sistema HVdc conectado en su barra más débil. Los alcances pueden servir tanto para planeamiento como para monitoreo en tiempo real de la estabilidad de tensión en sistemas eléctricos de potencia incluyendo nodos ca/cd.

  12. Nonlinear Parasitic Capacitance Modelling of High Voltage Power MOSFETs in Partial SOI Process

    DEFF Research Database (Denmark)

    Fan, Lin; Knott, Arnold; Jørgensen, Ivan Harald Holger

    2016-01-01

    : off-state, sub-threshold region, and on-state in the linear region. A high voltage power MOSFET is designed in a partial Silicon on Insulator (SOI) process, with the bulk as a separate terminal. 3D plots and contour plots of the capacitances versus bias voltages for the transistor summarize...

  13. 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...

  14. Effect of voltage sags on digitally controlled line connected switched-mode power supplies

    DEFF Research Database (Denmark)

    Török, Lajos; Munk-Nielsen, Stig

    2012-01-01

    Different voltage disorders like voltage fluctuations, sags, frequency variations may occur in the power supply networks due to different fault conditions. These deviations from normal operation affects in different ways the line connected devices. Standards were developed to protect and ensure i...

  15. Computation of Steady State Nodal Voltages for Fast Security Assessment in Power Systems

    DEFF Research Database (Denmark)

    Møller, Jakob Glarbo; Jóhannsson, Hjörtur; Østergaard, Jacob

    2014-01-01

    Development of a method for real-time assess-ment of post-contingency nodal voltages is introduced. Linear network theory is applied in an algorithm that utilizes Thevenin equivalent representation of power systems as seen from every voltage-controlled node in a network. The method is evaluated b...

  16. Study on AC loss measurements of HTS power cable for standardizing

    Science.gov (United States)

    Mukoyama, Shinichi; Amemiya, Naoyuki; Watanabe, Kazuo; Iijima, Yasuhiro; Mido, Nobuhiro; Masuda, Takao; Morimura, Toshiya; Oya, Masayoshi; Nakano, Tetsutaro; Yamamoto, Kiyoshi

    2017-09-01

    High-temperature superconducting power cables (HTS cables) have been developed for more than 20 years. In addition of the cable developments, the test methods of the HTS cables have been discussed and proposed in many laboratories and companies. Recently the test methods of the HTS cables is required to standardize and to common in the world. CIGRE made the working group (B1-31) for the discussion of the test methods of the HTS cables as a power cable, and published the recommendation of the test method. Additionally, IEC TC20 submitted the New Work Item Proposal (NP) based on the recommendation of CIGRE this year, IEC TC20 and IEC TC90 started the standardization work on Testing of HTS AC cables. However, the individual test method that used to measure a performance of HTS cables hasn’t been established as world’s common methods. The AC loss is one of the most important properties to disseminate low loss and economical efficient HTS cables in the world. We regard to establish the method of the AC loss measurements in rational and in high accuracy. Japan is at a leading position in the AC loss study, because Japanese researchers have studied on the AC loss technically and scientifically, and also developed the effective technologies for the AC loss reduction. The JP domestic commission of TC90 made a working team to discussion the methods of the AC loss measurements for aiming an international standard finally. This paper reports about the AC loss measurement of two type of the HTS conductors, such as a HTS conductor without a HTS shield and a HTS conductor with a HTS shield. The AC loss measurement method is suggested by the electrical method..

  17. Electrical Model of Balanced AC HTS Power Cable

    NARCIS (Netherlands)

    Zuijderduin, R.; Chevtchenko, O.; Smit, J.J.; Willen, D.; Melnik, I.; Geschiere, A.

    2012-01-01

    The future electricity grid will be more sustainable and it will have more power transmission and distribution capability with more electrical power added from decentralized sources on distribution level and from wind parks and other large sources on transmission level. More interconnections and mor

  18. PMU-Aided Voltage Security Assessment for a Wind Power Plant: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, H.; Zhang, Y. C.; Zhang, J. J.; Muljadi, E.

    2015-04-08

    Because wind power penetration levels in electric power systems are continuously increasing, voltage stability is a critical issue for maintaining power system security and operation. The traditional methods to analyze voltage stability can be classified into two categories: dynamic and steady-state. Dynamic analysis relies on time-domain simulations of faults at different locations; however, this method needs to exhaust faults at all locations to find the security region for voltage at a single bus. With the widely located phasor measurement units (PMUs), the Thevenin equivalent matrix can be calculated by the voltage and current information collected by the PMUs. This paper proposes a method based on a Thevenin equivalent matrix to identify system locations that will have the greatest impact on the voltage at the wind power plant’s point of interconnection. The number of dynamic voltage stability analysis runs is greatly reduced by using the proposed method. The numerical results demonstrate the feasibility, effectiveness, and robustness of the proposed approach for voltage security assessment for a wind power plant.

  19. PMU-Aided Voltage Security Assessment for a Wind Power Plant

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Huaiguang; Zhang, Yingchen; Zhang, Jun Jason; Muljadi, Eduard

    2015-10-05

    Because wind power penetration levels in electric power systems are continuously increasing, voltage stability is a critical issue for maintaining power system security and operation. The traditional methods to analyze voltage stability can be classified into two categories: dynamic and steady-state. Dynamic analysis relies on time-domain simulations of faults at different locations; however, this method needs to exhaust faults at all locations to find the security region for voltage at a single bus. With the widely located phasor measurement units (PMUs), the Thevenin equivalent matrix can be calculated by the voltage and current information collected by the PMUs. This paper proposes a method based on a Thevenin equivalent matrix to identify system locations that will have the greatest impact on the voltage at the wind power plant's point of interconnection. The number of dynamic voltage stability analysis runs is greatly reduced by using the proposed method. The numerical results demonstrate the feasibility, effectiveness, and robustness of the proposed approach for voltage security assessment for a wind power plant.

  20. The power supply system model of the process submersible device with AC power transmission over the cable-rope

    Science.gov (United States)

    Rulevskiy, V. M.; Bukreev, V. G.; Kuleshova, E. O.; Shandarova, E. B.; Shandarov, S. M.; Vasilyeva, Yu Z.

    2017-02-01

    A practical problem of power supply system modeling for the process submersible device with AC power transmission over the cable-rope was considered. The problem is highly relevant in developing and operation of submersible centrifugal pumps and submersibles. The results of modeling a symmetrical three-phase power supply system and their compliance with the real data are given at the paper. The obtained results in the mathematical and simulation models were similar.

  1. Voltage Stability Impact of Grid-Tied Photovoltaic Systems Utilizing Dynamic Reactive Power Control

    Science.gov (United States)

    Omole, Adedamola

    Photovoltaic (PV) DGs can be optimized to provide reactive power support to the grid, although this feature is currently rarely utilized as most DG systems are designed to operate with unity power factor and supply real power only to the grid. In this work, the voltage stability of a power system embedded with PV DG is examined in the context of the high reactive power requirement after a voltage sag or fault. A real-time dynamic multi-function power controller that enables renewable source PV DGs to provide the reactive power support necessary to maintain the voltage stability of the microgrid, and consequently, the wider power system is proposed. The loadability limit necessary to maintain the voltage stability of an interconnected microgrid is determined by using bifurcation analysis to test for the singularity of the network Jacobian and load differential equations with and without the contribution of the DG. The maximum and minimum real and reactive power support permissible from the DG is obtained from the loadability limit and used as the limiting factors in controlling the real and reactive power contribution from the PV source. The designed controller regulates the voltage output based on instantaneous power theory at the point-of-common coupling (PCC) while the reactive power supply is controlled by means of the power factor and reactive current droop method. The control method is implemented in a modified IEEE 13-bus test feeder system using PSCADRTM power system analysis software and is applied to the model of a Tampa ElectricRTM PV installation at Lowry Park Zoo in Tampa, FL. This dissertation accomplishes the systematic analysis of the voltage impact of a PV DG-embedded power distribution system. The method employed in this work bases the contribution of the PV resource on the voltage stability margins of the microgrid rather than the commonly used loss-of-load probability (LOLP) and effective load-carrying capability (ELCC) measures. The results of

  2. A Grid Voltage Measurement Method for Wind Power Systems during Grid Fault Conditions

    Directory of Open Access Journals (Sweden)

    Cheol-Hee Yoo

    2014-11-01

    Full Text Available Grid codes in many countries require low-voltage ride-through (LVRT capability to maintain power system stability and reliability during grid fault conditions. To meet the LVRT requirement, wind power systems must stay connected to the grid and also supply reactive currents to the grid to support the recovery from fault voltages. This paper presents a new fault detection method and inverter control scheme to improve the LVRT capability for full-scale permanent magnet synchronous generator (PMSG wind power systems. Fast fault detection can help the wind power systems maintain the DC-link voltage in a safe region. The proposed fault detection method is based on on-line adaptive parameter estimation. The performance of the proposed method is verified in comparison to the conventional voltage measurement method defined in the IEC 61400-21 standard.

  3. Practice and Prospect of AC/DC Hybrid Power Grid in Southern China

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    China Southern Power Grid is a unique EHV AC/DC hybrid transmission network that operates in China. In its service area, the distribution of energy resources and the development of economy are extremely unbalanced, so long-distance and bulk power transmission are needed; besides, the geography and climate conditions are serious, rains, fogs, lightning and typhoon as well as high temperature are common all the year round. Facing these challenges,the power grid enhanced stability control, improved the equipment and strengthen the network structure. In the future, the power grid plans to optimize the disposition of power sources and build digitalized power system.

  4. Observer-based higher order sliding mode control of power factor in three-phase AC/DC converter for hybrid electric vehicle applications

    Science.gov (United States)

    Liu, Jianxing; Laghrouche, Salah; Wack, Maxime

    2014-06-01

    In this paper, a full-bridge boost power converter topology is studied for power factor control, using output higher order sliding mode control. The AC/DC converters are used for charging the battery and super-capacitor in hybrid electric vehicles from the utility. The proposed control forces the input currents to track the desired values, which can control the output voltage while keeping the power factor close to one. Super-twisting sliding mode observer is employed to estimate the input currents and load resistance only from the measurement of output voltage. Lyapunov analysis shows the asymptotic convergence of the closed-loop system to zero. Multi-rate simulation illustrates the effectiveness and robustness of the proposed controller in the presence of measurement noise.

  5. AC Power Consumption of Single-Walled Carbon Nanotube Interconnects: Non-Equilibrium Green's Function Simulation

    Science.gov (United States)

    Yamamoto, Takahiro; Sasaoka, Kenji; Watanabe, Satoshi

    2012-04-01

    We theoretically investigate the emittance and dynamic dissipation of a nanoscale interconnect consisting of a metallic single-walled carbon nanotube using the non-equilibrium Green's function technique for AC electronic transport. We show that the emittance and dynamic dissipation depend strongly on the contact conditions of the interconnect and that the power consumption can be reduced by adjusting the contact conditions. We propose an appropriate condition of contact that yields a high power factor and low apparent power.

  6. High Voltage Coaxial Vacuum Gap Breakdown for Pulsed Power Liners

    Science.gov (United States)

    Cordaro, Samuel; Bott-Suzuki, Simon; Caballero Bendixsen, Luis Sebastian

    2015-11-01

    The dynamics of Magnetized Liner Inertial Fusion (MagLIF)1, are presently under detailed study at Sandia National Laboratories. Alongside this, a comprehensive analysis of the influence of the specific liner design geometry in the MagLIF system on liner initiation is underway in the academic community. Recent work at UC San Diego utilizes a high voltage pulsed system (25kV, 150ns) to analyze the vacuum breakdown stage of liner implosion. Such experimental analyses are geared towards determining how the azimuthal symmetry of coaxial gap breakdown affect plasma initiation within the liner. The final aim of the experimental analysis is to assess to what scale symmetry remains important at high (MV) voltages. An analysis of the above will utilize plasma self-emission via optical MCP, current measurements, voltage measurements near the gap, exact location of breakdown via 2D b-dot probe triangulation, as well as measuring the evolution of the B-field along the length of the liner via b-dot array. Results will be discussed along with analytical calculations of breakdown mechanisms

  7. Line-to-line voltage based modulation scheme for single-phase reduced switch ac-dc-ac converters to achieve improved performance

    DEFF Research Database (Denmark)

    Qin, Zian; Loh, Poh Chiang; Blaabjerg, Frede

    2015-01-01

    . With the SVPWM or DPWM proposed in literatures, the generation of the references is phase voltage based. But the phase voltages actually cannot be controlled directly by the PWM converter, since they can be influenced by both of terminal voltages and the load network while the PWM converter can only control...

  8. A dual voltage control strategy for single-phase PWM converters with power decoupling function

    DEFF Research Database (Denmark)

    Tang, Yi; Qin, Zian; Blaabjerg, Frede

    2015-01-01

    converter topology based on a symmetrical half bridge circuit is proposed to decouple the ripple power so that balanced instantaneous power flow is assured between source and load, and the required dc-link capacitance can be dramatically reduced. For proper closed-loop regulation, the small signal modeling......The inherent double line ripple power in single-phase systems is adverse to the performance of power electronics converters, e.g. limited lifetime due to the requirement of large electrolytic capacitors and low voltage control bandwidth due to harmonic disturbance. In this paper, an active...... of the proposed system is presented, and a dual voltage control strategy is then proposed, which comprises one voltage loop implemented in the synchronous reference frame for active power balancing, and another one implemented in the stationary reference frame for ripple power compensation. Special attention...

  9. Numerical Electric Field Analysis of Power Status Sensor Observing Power Distribution System Taking into Account Voltage Divider Measurement Circuit

    Science.gov (United States)

    Kubo, Takuro; Furukawa, Tatsuya; Itoh, Hideaki; Fukumoto, Hisao; Wakuya, Hiroshi; Ohchi, Masashi

    We have proposed and preproducted the voltage-current waveform sensor of resin molded type for measuring the power factor and harmonics in power distribution systems. We have executed numerical electromagnetic analyses using the finite element method to estimate the characteristics and behaviours of the sensor. Although the magnetic field analyses for the current sensor have involved the measurement circuit, the electric field analyses have not included the measurement circuit for measuring voltage waveforms of power lines. In this paper, we describe the electric field analyses with the measurement circuit and prove the insulating strength of the proposed sensor permissible to the use in 22kV power distribution systems.

  10. Challenge of Primary Voltage Control in Large Scale Wind Integrated Power System: A Danish Power System Case Study

    DEFF Research Database (Denmark)

    Rather, Zakir Hussain; Chen, Zhe; Thøgersen, Paul

    2013-01-01

    Grid integration of Renewable Energy (RE) at large scale poses vast majority of challenges to secure and stable operation of Power System. This paper presents the challenge of short circuit power and primary voltage control of wind integrated power system where majority of conventional generators...... are replaced by wind generators. The impact of large scale wind integration on fast reactive power support is studied in this paper. Considering both technical and economic aspects, alternatives to address the challenge of dynamic voltage support have also been demonstrated in this paper. A case study...

  11. Interface circuit with adjustable bias voltage enabling maximum power point tracking of capacitive energy harvesting devices

    Science.gov (United States)

    Wei, J.; Lefeuvre, E.; Mathias, H.; Costa, F.

    2016-12-01

    The operation analysis of a new interface circuit for electrostatic vibration energy harvesting with adjustable bias voltage is carried out in this paper. Two configurations determined by the open or closed states of an electronic switch are examined. The increase of the voltage across a biasing capacitor, occurring when the switch is open, is proved theoretically and experimentally. With the decrease of this biasing voltage which occurs naturally when the switch is closed due to imperfections of the circuit, the bias voltage can be maintained close to a target value by appropriate ON and OFF control of the switch. As the energy converted by the variable capacitor on each cycle depends on the bias voltage, this energy can be therefore accurately controlled. This feature opens up promising perspectives for optimization the power harvested by electrostatic devices. Simulation results with and without electromechanical coupling effect are presented. In experimental tests, a simple switch control enabling to stabilize the bias voltage is described.

  12. Power control of a wind farm with active stall wind turbines and AC grid connection

    DEFF Research Database (Denmark)

    Hansen, Anca Daniela; Sørensen, Poul; Iov, Florin

    This paper describes the design of a centralised wind farm controller for a wind farm made-up exclusively of active stall wind turbines with AC grid connection. The overall aim of such controller is to enable the wind farms to provide the best grid support. The designed wind farm control involves...... both the control on wind turbine level as well as the central control on the wind farm level. The ability of active stall wind farms with AC grid connection to regulate the power production to the reference power ordered by the operators is assessed and discussed by means of simulations....

  13. Research and Development of Bi-2223-Based AC Power Cables in Russia

    Science.gov (United States)

    Vysotsky, Vitaly; Fetisov, Sergey; Sytnikov, Viktor

    The Russian program for R&D of AC power cables has been started in 2005. During the program, the several 5m prototypes and witness samples of Bi-2223 based cables have been tested, as along with the 30m experimental three phase cable. Eventually 200m full size AC power cable with ratings 20 kV 1.5/2kA and 50/70MVA has been developed and successfully tested. The review of cable designs and test results is presented.

  14. A Pulsed Power Supply with Sag Compensation using Controlled Gradational Voltage

    Science.gov (United States)

    Suzuki, Akihiro; Yamada, Masaki; Tashiro, Shojirou; Iwata, Akihiko

    A pulsed power supply with sag compensation using controlled gradational voltage to increase the flatness of output waveforms has been developed.The sag compensation circuit consists of compensation units connected in series. Each compensation unit consists of capacitances, diodes, and semiconductor switches. The capacitances of each unit are charged with different voltages by 2n (V0, 2V0, 4V0, ···). The compensation voltages, which has 2n-1 steps, is generated by switching the semiconductor switches of each unit in a binary sequence. Using this method, compensation voltage waveforms up to 6.2kV with 31 steps can be obtained with 5 compensation units. The sag compensation circuit has been adapted to a direct switch type pulsed power supply, which generates 7kV pulsed voltage with a pulse width of 700μs, thus realizing sag compensation.

  15. An improved control method of power electronic converters in low voltage micro-grid

    DEFF Research Database (Denmark)

    Xiaofeng, Sun; Qingqiu, Lv; Yanjun, Tian

    2011-01-01

    control of the voltage and frequency deviation added to power references could achieve secondary regulation of the voltage and frequency. In this paper, the authors take the steady and transient transition of grid connecting and disconnecting of the micro-grid as an example, and demonstrate...... the place. The conventional droop control can perform the energy management in grid-connected mode, but may not so effective when micro-grid transferring between grid-connected mode and island mode. The paper analysis the micro-grid in different modes (Conventional droop control, Voltage reference...... compensation, Constant power output mode, Phase adjustment mode), and then proposes an overall control strategy for the micro-grid. The voltage reference compensation would minimize the steady-state error on the nominated operation point; the coordinate control of voltage and frequency with a feed forward...

  16. Management of Power Quality Issues in Low Voltage Networks using Electric Vehicles: Experimental Validation

    DEFF Research Database (Denmark)

    Martinenas, Sergejus; Knezovic, Katarina; Marinelli, Mattia

    2017-01-01

    As Electric Vehicles (EVs) are becoming more wide spread, their high power consumption presents challenges for the residential low voltage networks, especially when connected to long feeders with unevenly distributed loads. However, if intelligently integrated, EVs can also partially solve...... and voltage unbalances by a local smart charging algorithm based on a droop controller. In order to validate this capability, a low-voltage grid with a share of renewable resources is recreated in SYSLAB PowerLabDK. The experimental results demonstrate the advantages of the intelligent EV charging...

  17. Stability Analysis of DC-link Voltage Control on Autonomous Micro Hydro Power Plant System

    Directory of Open Access Journals (Sweden)

    Feri Yusivar

    2014-12-01

    Full Text Available Micro Hydro Power Plant has become one of the interesting topics to be researched nowadays. This paper deals with the stability analysis on control system of excitation voltage in Micro Hydro Power Plant. The control of this voltage can be achieved by controlling the Permanent Magnet Synchronous Machine (PMSM with particular algorithm so the voltage on the DC-link part of the system can be controlled. Without knowing the exact specification of system parameters, the system will be most likely unstable. The DC-link control system is modeled, simulated, and mathematically analyzed so the parameter specification for the stable system can be obtained.

  18. New online voltage stability margins and risk assessment for multi-bus smart power grids

    Science.gov (United States)

    Aldeen, M.; Saha, S.; Alpcan, T.; Evans, R. J.

    2015-07-01

    This paper presents a quantitative framework for assessment of voltage stability in smart power networks. First, new stability indices similar to gain and phase margins in linear time invariant control systems are introduced. These indices can be computed online in conjunction with load-flow calculations. Then, a novel risk assessment framework incorporating the new stability indices is developed to methodologically quantify the voltage stability risks a power system faces at any given operating condition. In contrast to existing local stability indices and qualitative risk approaches, the indices and framework introduced provide analytical and quantitative evaluation of voltage stability and associated risks. The results are illustrated with a numerical example.

  19. Sub-micrometer particles produced by a low-powered AC electric arc in liquids.

    Science.gov (United States)

    Jaworski, Jacek A; Fleury, Eric

    2012-01-01

    The article presents the report of the production of composites of sub-micrometer metal particles in matrix consisted of the metal compounds by means of an AC electric arc in water and paraffin solutions using electrodes carbon-metal and metal-metal (metal: Ni, Fe, Co, Cu). The advantage of this method is the low electric power (from 5 to 10 W) needed in comparison to standard DC arc-discharge methods (0.8 to 3 kW). This method enables the production of particles from conductive material also in wide range of temperature and in solvent which could be either transparent to light or opaque. Moreover the solvent can be electrolyte or insulating liquid. The microstructure of the composite layer was investigated by scanning electron microscopy (SEM), Electron Probe Microanalysis (EPMA) and X-ray. During particles production in water metal oxides were created. Additionally using cobalt-copper, nickel-copper as couple electrodes, insoluble in water copper (II) hydroxide crystal grains were created additionally which crystals shape was depended on transition metal. For iron-copper couple electrodes system the copper (II) hydroxide was not formed. Experiments with sequence production of Ni and Fe particles with C electrode assisting in molten paraffin let to obtain both Ni and Fe particles surrounded by paraffin. After solidification the material was insulator but if locally magnetic field influenced on the liquid solution in that place after solidification a new composite was created which was electric current conductor with resistivity around 0.1 omega x m, was attracted by magnetic field and presented magneto resistance around 0.4% in changing magnetic field in a range 150 mT. After mixing the concentrated paraffin with normal paraffin resistivity of the mixture increased and it became photosensitive and created small voltage under light influence.

  20. Artificial Neural Network Application for Power Transfer Capability and Voltage Calculations in Multi-Area Power System

    Directory of Open Access Journals (Sweden)

    Palukuru NAGENDRA

    2010-12-01

    Full Text Available In this study, the use of artificial neural network (ANN based model, multi-layer perceptron (MLP network, to compute the transfer capabilities in a multi-area power system was explored. The input for the ANN is load status and the outputs are the transfer capability among the system areas, voltage magnitudes and voltage angles at concerned buses of the areas under consideration. The repeated power flow (RPF method is used in this paper for calculating the power transfer capability, voltage magnitudes and voltage angles necessary for the generation of input-output patterns for training the proposed MLP neural network. Preliminary investigations on a three area 30-bus system reveal that the proposed model is computationally faster than the conventional method.

  1. Six switches solution for single-phase AC/DC/AC converter with capability of second-order power mitigation in DC-link capacitor

    DEFF Research Database (Denmark)

    Liu, Xiong; Wang, Peng; Loh, Poh Chiang

    2011-01-01

    This paper proposes an approach for DC-link second-order harmonic power cancellation in single-phase AC/DC/AC converter with reduced number of switches. The proposed six-switch converter has two bridges with three switches in each of them, where the middle switch in each bridge is shared by the AC...... on their modulation indices of the six-switch converter, and high modulation indices are proved to be feasible for second-order power cancellation in the DC-link based on the phase difference analysis. Both reduced switch numbers and DC electrolytic capacitor size can be achieved using the proposed converter...

  2. A Low-Power and Low-Voltage Power Management Strategy for On-Chip Micro Solar Cells

    Directory of Open Access Journals (Sweden)

    Ismail Cevik

    2015-01-01

    Full Text Available Fundamental characteristics of on-chip micro solar cell (MSC structures were investigated in this study. Several MSC structures using different layers in three different CMOS processes were designed and fabricated. Effects of PN junction structure and process technology on solar cell performance were measured. Parameters for low-power and low-voltage implementation of power management strategy and boost converter based circuits utilizing fractional voltage maximum power point tracking (FVMPPT algorithm were determined. The FVMPPT algorithm works based on the fraction between the maximum power point operation voltage and the open circuit voltage of the solar cell structure. This ratio is typically between 0.72 and 0.78 for commercially available poly crystalline silicon solar cells that produce several watts of power under typical daylight illumination. Measurements showed that the fractional voltage ratio is much higher and fairly constant between 0.82 and 0.85 for on-chip mono crystalline silicon micro solar cell structures that produce micro watts of power. Mono crystalline silicon solar cell structures were observed to result in better power fill factor (PFF that is higher than 74% indicating a higher energy harvesting efficiency.

  3. A dual voltage control strategy for single-phase PWM converters with power decoupling function

    DEFF Research Database (Denmark)

    Tang, Yi; Qin, Zian; Blaabjerg, Frede

    2014-01-01

    on a symmetrical half bridge circuit is proposed to decouple the ripple power so that balanced instantaneous power flow is assured between source and load, and the required dc-link capacitance can be dramatically reduced. For proper closed-loop regulation, the small signal modeling of the proposed system...... is presented, and a dual voltage control strategy is then proposed, which comprises one voltage loop implemented in the synchronous reference frame for active power balancing, and another one implemented in the harmonic reference frame for ripple power compensation. Special attention is given to the bandwidth...

  4. System Frequency as Information Carrier in AC Power Systems

    DEFF Research Database (Denmark)

    Douglass, Philip James; Heussen, Kai; You, Shi

    2015-01-01

    Power generators contain control systems able to regulate system frequency, but the frequency setpoint values are only rarely modified from nominal values. This paper describes design considerations for a communication system from generators to frequency sensitive distributed energy resourc es (FS...... to carry information: First, a protocol for dispatching blocks of FS- DER that is suitable for systems restricted to relatively slow rates of change of frequency (ROCOF). Second, for systems that allow higher ROCOF values, the feasibility of using power generation resources as a power line communication......-DER) using changes to frequency setpoint values of genera- tors. Signaling discrete system states by generating off-nominal system frequency values can be used as a novel narrowband unidirectional broadcast communications channel. This paper describes two protocols for utilizing off-nominal frequencies...

  5. AC losses in superconductors with a power-law constitutive relation

    Energy Technology Data Exchange (ETDEWEB)

    Agassi, Y.D., E-mail: yehoshua.agassi@navy.mil

    2015-10-15

    Highlights: • Derivation of power-law constitutive-relation from distributed Anderson–Kim theory. • The electric-field for HTS constitutive-relation satisfies nonlinear heat-equation. • For slab, AC losses scale as B{sub 0}{sup m}, m = 3–4 and I{sup 3} with field-amplitude and current, respectively. • Calculated pinning potential, AC-losses scaling is consistent with BSCCO data. - Abstract: The observed constitutive relation between the electrical field and current density in cuprates high temperature superconductors is a power-law of the current. This functional dependence is presumably related to the giant flux-creep domain. It is shown that this constitutive relation reflects the statistical spread of the pinning potential associated with creep motion of vortex bundles. The AC losses emanating from a power-law constitutive relation are calculated in an approach focused on the superconductor’s electric field. For a slab geometry in the presence of a parallel AC magnetic field or transport current, the calculated AC-loss scaling laws are consistent with BSCCO data and the critical state model. Extensions of the approach are briefly discussed.

  6. 船用交流中压断路器开断性能相关参数分析%Analysis of Parameters for Breaking Performance of Marine Medium Voltage AC Circuit Breakers

    Institute of Scientific and Technical Information of China (English)

    杨青

    2013-01-01

    According to the characteristics of marine medium voltage power system,the parameters closely related to the breaking performance of medium voltage AC circuit breaker were analyzed.It is shown that the key performance parameters in land standards,such as rated breaking current,making current,power frequency recovery voltage,transient recovery voltage,electrical life and so on,basically meet the marine requirements after conversion. But there are also some individual parameters need to be studied further to decide.%根据船舶中压电力系统的特点,对中压断路器开断性能密切相关的参数进行了分析。结果表明,陆用标准中额定短路开断电流和关合电流、工频恢复电压和瞬态恢复电压、电寿命等参数经过换算、折算,基本上符合船用要求,个别参数是否合适有待进一步研究。

  7. Effective variable switching point predictive current control for ac low-voltage drives

    Science.gov (United States)

    Stolze, Peter; Karamanakos, Petros; Kennel, Ralph; Manias, Stefanos; Endisch, Christian

    2015-07-01

    This paper presents an effective model predictive current control scheme for induction machines driven by a three-level neutral point clamped inverter, called variable switching point predictive current control. Despite the fact that direct, enumeration-based model predictive control (MPC) strategies are very popular in the field of power electronics due to their numerous advantages such as design simplicity and straightforward implementation procedure, they carry two major drawbacks. These are the increased computational effort and the high ripples on the controlled variables, resulting in a limited applicability of such methods. The high ripples occur because in direct MPC algorithms the actuating variable can only be changed at the beginning of a sampling interval. A possible remedy for this would be to change the applied control input within the sampling interval, and thus to apply it for a shorter time than one sample. However, since such a solution would lead to an additional overhead which is crucial especially for multilevel inverters, a heuristic preselection of the optimal control action is adopted to keep the computational complexity at bay. Experimental results are provided to verify the potential advantages of the proposed strategy.

  8. High Voltage Power Converter for Large Wind Turbine

    DEFF Research Database (Denmark)

    Sztykiel, Michal

    performance has been achieved by the transformer-less turbine with a back-to-back modular multilevel converter (MMC) topology, which is single grounded only through its DC link common-mode point. It has also occurred that the results derived from losses and short circuit analyses have become advantageous over...... system operates at 20 kV level - identical as for the collector distribution network. Medium voltage operation allows the converter unit along with the filter to be installed on the base platform inside the tower. In this manner, more space in the nacelle can be flexibly accommodated by the mechanical...

  9. Improved direct power control of a grid-connected voltage source converter during network unbalance

    Institute of Scientific and Technical Information of China (English)

    Peng ZHOU; Wei ZHANG; Yi-kang HE; Rong ZENG

    2010-01-01

    This paper deals with an improved direct power control(DPC)strategy for the pulse width modulation(PWM)voltage source converter(VSC)under unbalanced grid voltage conditions.In order to provide enhanced control performance for the VSC,the resonant controllers tuned at the double grid frequency are applied in the DPC design to eliminate the power pulsations and dc link voltage ripples produced by the transient unbalanced grid faults.In this way,the output power and dc link voltage of the VSC can be directly regulated without positive and negative sequential decomposition.As a result,and as has been verified by experiment,the proposed method can provide fast dynamic response with easy implementation.

  10. Performance Comparison of Voltage Stability Indices for Weak Bus Identification in Power Systems

    Science.gov (United States)

    Verayiah, R.; Mohamed, A.; Shareef, H.; Zainal Abidin, I. Hj

    2013-06-01

    Voltage collapse event is identified as complex and localized in nature but its effect is extensive once occurred. The vital effect of voltage collapse would be the total system collapse or blackouts which would cost a large loss to utility companies. Eventually, on- line monitoring of power system stability has become an important factor for electric power utilities. The last utmost option to avert voltage collapse incident from occurring is by the implementation of under voltage load shedding scheme. The identification of location for load shedding is the main motivation of the study. The weakest bus in a power system is identified as the location for load shedding. This location is obtained using voltage stability index Ld. The performance and effectiveness of Ld index is compared with Fast Voltage Stability Index (FVSI) and Le Index. The results obtained indicate that Ld Index can be used to identify the weak bus in a power system and consequently for the placement of UVLS relays in a power system network.

  11. Research of Characteristics of the Low Voltage Power Line in Underground Coal Mine

    Science.gov (United States)

    Wei, Shaoliang; Qin, Shiqun; Gao, Wenchang; Cheng, Fengyu; Cao, Zhongyue

    The power line communications (PLCs) can count on existing electrical connections reaching each corner in the locations where such applications are required, so signal transmission over power lines is nowadays gaining more and more interest for applications like internet. The research of characteristics of the low voltage power line is the fundamental and importance task. This work presents a device to test the characteristics of the low voltage power line. The low voltage power line channel characteristics overground and the channel characteristics underground were tested in using this device. Experiments show that, the characteristics are different between the PLCs channel underground coal mine and the PLC channel overground. Different technology should be adopted to structure the PLCs channel model underground coal mine and transmit high speed digital signal. But how to use the technology better to the high-speed digital communication under coal mine is worth of further studying.

  12. A dual voltage control strategy for single-phase PWM converters with power decoupling function

    DEFF Research Database (Denmark)

    Tang, Yi; Qin, Zian; Blaabjerg, Frede

    2014-01-01

    The inherent double line ripple power in singlephase systems is adverse to the converter performance, e.g. limited lifetime due to the requirement of large electrolytic capacitors and low voltage control bandwidth due to harmonic disturbance. In this paper, an active converter topology based...... on a symmetrical half bridge circuit is proposed to decouple the ripple power so that balanced instantaneous power flow is assured between source and load, and the required dc-link capacitance can be dramatically reduced. For proper closed-loop regulation, the small signal modeling of the proposed system...... is presented, and a dual voltage control strategy is then proposed, which comprises one voltage loop implemented in the synchronous reference frame for active power balancing, and another one implemented in the harmonic reference frame for ripple power compensation. Special attention is given to the bandwidth...

  13. A zero-voltage switching technique for minimizing the current-source power of implanted stimulators.

    Science.gov (United States)

    Çilingiroğlu, Uğur; İpek, Sercan

    2013-08-01

    The current-source power of an implanted stimulator is reduced almost to the theoretical minimum by driving the electrodes directly from the secondary port of the inductive link with a dedicated zero-voltage switching power supply. A feedback loop confined to the secondary of the inductive link adjusts the timing and conduction angle of switching to provide just the right amount of supply voltage needed for keeping the current-source voltage constant at or slightly above the compliance limit. Since drive is based on current rather than voltage, and supply-voltage update is near real-time, the quality of the current pulses is high regardless of how the electrode impedance evolves during stimulation. By scaling the switching frequency according to power demand, the technique further improves overall power consumption of the stimulator. The technique is implemented with a very simple control circuitry comprising a comparator, a Schmitt trigger and a logic gate of seven devices in addition to an on-chip switch and an off-chip capacitor. The power consumed by the proposed supply circuit itself is no larger than what the linear regulator of a conventional supply typically consumes for the same stimulation current. Still, the sum of supply and current-source power is typically between 20% and 75% of the conventional source power alone. Functionality of the proposed driver is verified experimentally on a proof-of-concept prototype built with 3.3 V devices in a 0.18 μm CMOS technology.

  14. Adaptive voltage control in power systems modeling, design and applications

    CERN Document Server

    Fusco, Giuseppe

    2006-01-01

    Large-scale power cuts in both North America and Europe emphasised the need to maintain an adequate supply of high-quality electricity. This book offers information on the relatively low-cost of doing so using self-regulating control mechanisms. It is of interest to the practising power/control engineer and to academics needing industrial inputs.

  15. Direct-conversion switching-mode audio power amplifier with active capacitive voltage clamp

    DEFF Research Database (Denmark)

    Ljusev, Petar; Andersen, Michael Andreas E.

    2005-01-01

    This paper discusses the advantages and problems when implementing direct energy conversion switching-mode audio power amplifiers. It is shown that the total integration of the power supply and Class D audio power amplifier into one compact direct converter can simplify the design, increase...... efficiency, reduce the product volume and lower its cost. As an example, the principle of operation and the measurements made on a direct-conversion switching-mode audio power amplifier with active capacitive voltage clamp are presented....

  16. Experimental investigation of the loss characteristics of superconductors for AC power applications

    NARCIS (Netherlands)

    Overbeeke, van Frank; Oordt, Klaas; Klundert, van de Louis J.M.

    1985-01-01

    Recent studies confirm the economical feasibility of the application of superconductors in AC power apparatus. The low-loss conductor which has been proposed still only exists in theory. Simple calculations show that the economic criterion described by Ogasawara and Hlásnik is inaccurate because of

  17. A Direct Power Conversion Topology for Grid Integration of Hybrid AC/DC Energy Resources

    DEFF Research Database (Denmark)

    Liu, Xiong; Loh, Poh Chiang; Wang, Peng;

    2013-01-01

    This paper proposes a multiple-input versatile matrix converter (VMC) for integrating hybrid ac/dc energy resources and storages to the power grid. The VMC is developed from the traditional indirect matrix converter but operates in the reverse-boost mode rather than in the forward-buck mode. The ...

  18. Low Power, Reduced Dynamic Voltage Swing Domino Logic Circuits

    OpenAIRE

    Salendra.Govindarajulu; Dr.T.Jayachandra Prasad; Rangappa, P

    2010-01-01

    Dynamic domino logic circuits are widely used in modern digital VLSI circuits. These dynamic circuits are often favoured in high performance designs because of the speed advantage offered over static CMOS logic circuits. The main drawbacks of dynamic logic are a lack of design automation, a decreased tolerance to noise and increased power dissipation. In this work, new reduced – swing domino logic techniques which provide significant low power dissipation as compared to traditional domino cir...

  19. AC Power Supply for Wobbler Magnet of the MC-50 Cyclotron

    CERN Document Server

    Kim, Yu-Seok; Kang, Bong-Koo; Lee, Hong-Gi; Park, Ki-Hyeon; Wha Chung, Chin; Woo Lee, Wol

    2005-01-01

    The MC-50 cyclotron (k=50) produces the ion beam for nuclear physics, chemistry, and applied researches in Korea. It has a small beam diameter with Gaussian beam shape, whereas many users want a beam irradiation on a large target. A wobbler magnet and an AC power supply were designed and constructed to meet the users' requirement. The power supply has two independently operating channels for the vertical and horizontal coils of the wobbler magnet. The frequency of the AC power supply for both coils is programmable from 1 to 20 Hz in a step of 1 Hz, and the maximum rms output current is 12 A. Various properties of the power supply and experimental results are given in the paper.

  20. Multiobjective Optimal Reactive Power Dispatch Considering Voltage Stability Using Shuffled Frog Leaping Algorithm

    Directory of Open Access Journals (Sweden)

    V. Tamilselvan

    2015-05-01

    Full Text Available This study addresses a shuffled frog leaping algorithm for solving the multi-objective reactive power dispatch problem in a power system. Optimal Reactive Power Dispatch (ORPD is formulated as a nonlinear, multi-modal and mixed-variable problem. The intended technique is based on the minimization of the real power loss, minimization of voltage deviation and maximization of the voltage stability margin. Generator voltages, capacitor banks and tap positions of tap changing transformers are used as optimization variables of this problem. A memetic meta-heuristic named as shuffled frog-leaping algorithm is intended to solve multi-objective optimal reactive power dispatch problems considering voltage stability margin and voltage deviation. The Shuffled Frog-Leaping Algorithm (SFLA is a population-based cooperative search metaphor inspired by natural memetics. The algorithm contains elements of local search and global information exchange. The most important benefit of this algorithm is higher speed of convergence to a better solution. The intended method is applied to ORPD problem on IEEE 57 bus power systems and compared with two versions of differential evolutionary algorithm. The simulation results show the effectiveness of the intended method.

  1. A combined uninterruptible power supply and dynamic voltage compensator using a flywheel energy storage system

    Science.gov (United States)

    Weissbach, Robert Stephen

    Due to recent technological advances in materials, power electronics, magnetic bearings and controls, the flywheel energy storage system has become a viable alternative to electrochemical batteries. The advantages of the flywheel system are its higher power density, insensitivity to environmental conditions, lack of hazardous materials and ease of checking the charge. One potential use is in a power distribution system. The flywheel energy storage system may be used as both an uninterruptible power supply as well as a means of dynamic voltage compensation to protect critical loads on radial distribution feeders. To perform dynamic voltage compensation, a comparison was performed which shows that the series injection of power is preferable to the shunt injection of power in utilizing the available kVA of the flywheel system motor/generator. The system was designed and modeled using the Electromagnetic Transients Program to ensure a proper dynamic response of the flywheel energy storage system in either mode of operation. The design incorporates a boost converter on the dc link to enable the load voltage to be maintained as the flywheel spins down. The same boost converter also allows for extended operation in the series compensation mode, by implementing a novel control scheme where sinusoidal pulse width modulation control is used for to compensate for smaller supply voltage dips, while the boost converter is used to control the compensation for larger supply voltage dips.

  2. Development of high voltage power supply for the KSTAR 170 GHz ECH and CD system

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, J.H., E-mail: jhjeong@nfri.re.kr [National Fusion Research Institute, Daejeon (Korea, Republic of); Bae, Y.S.; Joung, M.; Kim, H.J.; Park, S.I.; Han, W.S.; Kim, J.S.; Yang, H.L.; Kwak, J.G. [National Fusion Research Institute, Daejeon (Korea, Republic of); Sakamoto, K.; Kajiwara, K.; Oda, Y.; Hayashi, K. [Japan Atomic Energy Agency, Naka (Japan)

    2013-06-15

    Highlights: • A 3.6 MW (−66 kV/55 A) gyrotron power supply system was developed for the 170 GHz ECH system in KSTAR. • The main power supply includes a total of 32 PSM based HV power supply modules. • The voltage regulation of individual HV power module and LV power module is 3 kV and 0.5 kV, respectively. • The gyrotron is protected by means of a fast solid-state switch (MOS-FET). • The HV switching system can turn off the 60 kV to the cathode within 3 μs in the event of gyrotron faults. -- Abstract: A 3.6 MW (66 kV/55 A) DC power supply system was developed for the 170 GHz EC H and CD system in KSTAR. The power supply system consists of a cathode power supply (CPS), an anode power supply (APS) and a body power supply (BPS). The cathode power supply is capable of supplying a maximum voltage of −66 kV and a current of 55 A to the cathode with respect to the collector using pulse step modulation (PSM). The high voltage switching system for the cathode is made by a fast MOS-FET solid-state switch which can turn off the high voltage to the cathode within 3 μs in the occurrence of gyrotron faults. The APS is a voltage divider system consisting of a fixed resistor and zener diode units with the capability of 60 kV stand-off voltage. The anode voltage with respect to the cathode is controlled in a range of 0–60 kV by turning the MOS-FET switches connected in parallel to each zener diode on and off. For high frequency current modulation of the gyrotron, the parallel discharge switch is introduced between the cathode and anode in order to clamp the charged voltage in the stray capacitance. The BPS is a DC power supply with the capability of 50 kV/160 mA. The nominal operation parameter of BPS was 23 kV and 10 mA, respectively, and the voltage output is regulated with a stability of 0.025% of the rated voltage. The series MOS-FET solid-state switch is used for on/off modulation in the body voltage sychronizing with anode voltage. The parallel discharge

  3. Multifunctional Voltage Source Inverter for Renewable Energy Integration and Power Quality Conditioning

    OpenAIRE

    2014-01-01

    In order to utilize the energy from the renewable energy sources, power conversion system is necessary, in which the voltage source inverter (VSI) is usually the last stage for injecting power to the grid. It is an economical solution to add the function of power quality conditioning to the grid-connected VSI in the low-voltage distribution system. Two multifunctional VSIs are studied in this paper, that is, inductive-coupling VSI and capacitive-coupling VSI, which are named after the fundame...

  4. Design to conditioning circuits of dynamic compensation of reactive power in the intelligence voltage controller

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    <正>The paper introduces one design idea that making use of SCM to control Real-timely the dynamic compensation of reactive power.Firstly,design one Circuit to Sample the voltage and current,and by these datas we can easily calculate the power factor,and Voltage controller in the microcontroller to determine whether input the compensation capacitance according to the size of power factor,the paper also analyzes the principle of capacitance compensation and calculation method. Dynamic compensation for the entire process is quick and accurate.

  5. Coordinated voltage control in smart grids subject to a fair contribution of reactive power

    Energy Technology Data Exchange (ETDEWEB)

    Kolenc, Marko; Papic, Igor; Blazic, Bostjan [Ljubljana Univ. (Slovenia). Faculty of Electrical Engineering

    2012-07-01

    The paper analyses the influence of distributed generation (DG) on voltage profile and distribution losses. Connection of DG units to a distribution network results in a local voltage increase and usually reduction of losses. The focus of the paper is on development of a control strategy to keep the voltage within permissible limits, minimize losses and assure fairness regarding reactive power contributions. As the new technologies nowadays allow bidirectional data flow in almost real time, more active participation of generators in voltage control is possible. Different solutions were evaluated by means of simulations. The simulated network was an actual Slovenian medium-voltage distribution network which covers a large area with diverse feeders and thus gives relatively general results. The network was modified by increasing the number of DG (especially photovoltaic) as the growth of DG is very fast in Slovenia. (orig.)

  6. Voltage and Frequency Control for Future Power Systems: the ELECTRA IRP Proposal

    DEFF Research Database (Denmark)

    D’hulst, R.; Merino Fernandez, J.; Rikos, E.;

    2015-01-01

    In this paper a high level functional architecture for frequency and voltage control for the future (2030+) power system is presented. The proposal suggests a decomposition of the present organization of power system operation into a ”web of cells”. Each cell in this web is managed by a single sy...

  7. Comparison of two voltage control strategies for a wind power plant

    DEFF Research Database (Denmark)

    Martinez, Jorge; Kjær, Philip C.; Rodriguez, Pedro;

    2011-01-01

    Larger percentages of wind power penetration translate to more demanding requirements from grid codes. Recently, voltage support at the point of connection has been introduced by several grid codes from around the world, thus, making it important to analyze this control when applied to wind power...

  8. On-site Testing and PD Diagnosis of High Voltage Power Cables

    NARCIS (Netherlands)

    Gulski, E.; Cichecki, P.; Wester, F.; Smit, J.J.; Bodega, R.; Hermans, T.J.W.H.; Seitz, P.P.; Quak, B.; De Vries, F.

    2008-01-01

    In addition to after-laying of new-installed high voltage (HV) power cables the use of on-site non-destructive on-site testing and diagnosis of service aged power cables is becoming an important issue to determine the actual condition of the cable systems and to determine the future performances. In

  9. Overview of power converter designs feasible for high voltage transformer-less wind turbine

    DEFF Research Database (Denmark)

    Sztykiel, Michal

    2011-01-01

    voltage design enables low power losses and elimination of bulky step-up transformer from the wind turbine system. However, new challenges appear for such topology, which have to be properly identified and successfully overcome. This paper presents possible concept for transformer-less wind turbine......Many leading wind turbine manufacturers are pushing forward in variable-speed wind turbines, often exceeding 5 MW. Therefore, novel designs and concepts for optimal high power wind turbines appeared. One of the most promising concepts is the high voltage (10-35 kV) transformer-less topology. High...... topology along with an overview of most promising candidates for optimal full-scale power converter design. Study is carried with proposed and justified high voltage wind turbine application along with selection of existing and most promising multilevel power converter topologies, which could...

  10. Opposition-Based Improved PSO for Optimal Reactive Power Dispatch and Voltage Control

    Directory of Open Access Journals (Sweden)

    Shengrang Cao

    2015-01-01

    Full Text Available An opposition-based improved particle swarm optimization algorithm (OIPSO is presented for solving multiobjective reactive power optimization problem. OIPSO uses the opposition learning to improve search efficiency, adopts inertia weight factors to balance global and local exploration, and takes crossover and mutation and neighborhood model strategy to enhance population diversity. Then, a new multiobjective model is built, which includes system network loss, voltage dissatisfaction, and switching operation. Based on the market cost prices, objective functions are converted to least-cost model. In modeling process, switching operation cost is described according to the life cycle cost of transformer, and voltage dissatisfaction penalty is developed considering different voltage quality requirements of customers. The experiment is done on the new mathematical model. Through the simulation of IEEE 30-, 118-bus power systems, the results prove that OIPSO is more efficient to solve reactive power optimization problems and the model is more accurate to reflect the real power system operation.

  11. Power Loss Analysis and Comparision of DC and AC Side Decoupling Module in a H-bridge Inverter

    DEFF Research Database (Denmark)

    Ma, Siyuan; Wang, Haoran; Zhu, Guorong;

    2016-01-01

    In single-phase inverters, a considerable amount of low-frequency ripples appear on the DC side due to the instantaneous power imbalance between the DC side and AC side. Recently, active methods using film capacitors or inductors as ripple power storage components introduced at the DC or AC side...

  12. AC/DC and DC/AC Converty Circuits in Power Supply Equipment%电源设备中AC/DC和DC/AC变换电路

    Institute of Scientific and Technical Information of China (English)

    杨碧石

    2001-01-01

    电源设备中根据电路变换功能来看,可分为四种类型:AC/DC、DC/AC、DC/DC、AC/AC,本文对AC/DC、DC/AC这两种变换的工作原理进行分析阐述并讨论每种电路的应用领域.

  13. Detecting Power Voltage Dips using Tracking Filters - A Comparison against Kalman

    Directory of Open Access Journals (Sweden)

    STANCIU, I.-R.

    2012-11-01

    Full Text Available Due of its significant economical impact, Power-Quality (PQ analysis is an important domain today. Severe voltage distortions affect the consumers and disturb their activity. They may be caused by short circuits (in this case the voltage drops significantly or by varying loads (with a smaller drop. These two types are the PQ currently issues. Monitoring these phenomena (called dips or sags require powerful techniques. Digital Signal Processing (DSP algorithms are currently employed to fulfill this task. Discrete Wavelet Transforms, (and variants, Kalman filters, and S-Transform are currently proposed by researchers to detect voltage dips. This paper introduces and examines a new tool to detect voltage dips: the so-called tracking filters. Discovered and tested during the cold war, they can estimate a parameter of interest one-step-ahead based on the previously observed values. Two filters are implemented. Their performance is assessed by comparison against the Kalman filter?s results.

  14. Optimal Placement of Static Compensators for Global Voltage Sag Mitigation and Power System Performance Improvement

    Directory of Open Access Journals (Sweden)

    M.A. Ali

    2015-06-01

    Full Text Available This study presents a new multi-objective approach for optimal placement of Static Compensator (STATCOM for global (overall voltage sag mitigation as well as for power system performance improvement. The problem is formulated as a non linear constrained multi-objective optimization problem and solved using Genetic Algorithm (GA. The proposed method determines optimal locations of STATCOMs which simultaneously minimizes the overall voltage sags at network buses, bus voltage deviation and system real power loss and maximizes the voltage stability margin of the system. The proposed approach has been applied on IEEE 24-bus Reliability Test System (RTS and IEEE 57-bus test systems. The details of implementation and simulation results are presented. The application results are promising and encouraging.

  15. Mechanism of Occurring Over-Voltage Phenomena in Distributed Power System on Energization of Transformers

    Science.gov (United States)

    Nakachi, Yoshiki; Ueda, Fukashi; Kajikawa, Takuya; Amau, Tooru; Kameyama, Hirokazu; Ito, Hisanori

    This paper verifies the mechanism of occurring over voltage phenomena in the distributed power system on energizing the transformer. This over-voltage, which is observed at the actual distributed power system, with heavy inrush current is found to occur at about 0.1-0.2sec after the energizing and continue for a duration of more than 0.1[sec]. There is a concern that this over-voltage may operate the protection relay and deteriorate the insulation of apparatus. It is basically caused by the resonance between the shunt capacitors and saturated/unsaturated magnetizing inductance of transformer, system inductance. By using analytical formulation of a simple equivalent circuit, its mechanism has been verified through simulations carried out by using EMTP. Moreover, the sympathetic interaction between transformers is prolonged the duration of the over-voltage by the field test data is discussed in this paper.

  16. An Optimized Reactive Power Control of Distributed Solar Inverters in Low Voltage Networks

    DEFF Research Database (Denmark)

    Demirok, Erhan; Sera, Dezso; Teodorescu, Remus

    2011-01-01

    This study examines the reactive power ancillary services of solar inverters which are connected to low voltage (LV) distribution networks by giving attention to the grid voltage support service and grid losses. Two typical reference LV distribution network models as suburban and farm...... are introduced from the literature in order to evaluate contribution of two static droop strategies cosφ(P) and Q(U) on the grid voltage. Photovoltaic (PV) hosting capacities of the suburban and farm networks are estimated and the most predominant limitations of connecting more solar inverters are emphasized...... for each network type. Regarding the overloading of MV/LV distribution transformers, overloading of lines and the grid overvoltage limitations, new local grid voltage support methods (cosφ(P,U) and Q(U,P)) are also proposed. Resulting maximum allowable penetration levels with different reactive power...

  17. Design of Low Voltage Low Power CMOS OP-AMP

    OpenAIRE

    2014-01-01

    Operational amplifiers are an integral part of many analog and mixed signal systems. As the demand for mixed mode integrated circuits increases, the design of analog circuits such as operational amplifiers in CMOS technology becomes more critical. This paper presents a two stage CMOS operational amplifier, which operates at ±1.8V power supply using TSMC 0.18um CMOS technology. The OP-AMP designed exhibit unity gain frequency of 12.6 MHz, and gain of 55.5db with 300uw power dissipa...

  18. A combined compensation method for the output voltage of an insulated core transformer power supply

    Science.gov (United States)

    Yang, L.; Yang, J.; Liu, K. F.; Qin, B.; Chen, D. Z.

    2014-06-01

    An insulated core transformer (ICT) power supply is an ideal high-voltage generator for irradiation accelerators with energy lower than 3 MeV. However, there is a significant problem that the structure of the segmented cores leads to an increase in the leakage flux and voltage differences between rectifier disks. A high level of consistency in the output of the disks helps to achieve a compact structure by improving the utilization of both the rectifier components and the insulation distances, and consequently increase the output voltage of the power supply. The output voltages of the disks which are far away from the primary coils need to be improved to reduce their inhomogeneity. In this study, by investigating and comparing the existing compensation methods, a new combined compensation method is proposed, which increases the turns on the secondary coils and employs parallel capacitors to improve the consistency of the disks, while covering the entire operating range of the power supply. This method turns out to be both feasible and effective during the development of an ICT power supply. The non-uniformity of the output voltages of the disks is less than 3.5% from no-load to full-load, and the power supply reaches an output specification of 350 kV/60 mA.

  19. Study of the plasma interference with high voltage electrode array for space power application

    OpenAIRE

    Iwasa, Minoru; TANAKA, KOJI; Sasaki, Susumu; ODAWARA, OSAMU; 岩佐 稔; 田中 孝治; 佐々木 進; 小田原 修

    2005-01-01

    We are studying the problems associated with high voltage power systems in space. Especially we are interested in the potential distribution of the solar array that is resistant to the electrical discharge. We have carried out experiments on the interaction between the high voltage solar array and the ambient plasma. In the experiment, an array of electrodes distributed on the insulation panel was used to simulate the inter-connectors of the solar array. An electrode array without the insulat...

  20. Development of Medium-Voltage and Large-Capacity Uninterruptible Power Supply System

    Science.gov (United States)

    Fujii, Kansuke; Kikuchi, Takayuki; Yoda, Kazuyuki

    A 2-MVA uninterruptible power supply (UPS) system has been developed for compensating for voltage dips in a medium voltage network. The UPS system realizes a high efficiency (99.7%) during single-pulse switching. In this paper, the UPS configurations, storage devices, and transfer switches are compared. Thereafter, the details of the UPS system, the results of the short-circuit test and the system efficiencies are described.

  1. Insulation co-ordination in high-voltage electric power systems

    CERN Document Server

    Diesendorf, W

    2015-01-01

    Insulation Co-ordination in High-Voltage Electric Power Systems deals with the methods of insulation needed in different circumstances. The book covers topics such as overvoltages and lightning surges; disruptive discharge and withstand voltages; self-restoring and non-self-restoring insulation; lightning overvoltages on transmission lines; and the attenuation and distortion of lightning surges. Also covered in the book are topics such as the switching surge designs of transmission lines, as well as the insulation coordination of high-voltage stations. The text is recommended for electrical en

  2. Voltage stability issues for a benchmark grid model including large scale wind power

    DEFF Research Database (Denmark)

    Eek, Jarle; Lund, Torsten; Di Marzio, Guiseppe

    2006-01-01

    The objective of the paper is to investigate how the voltage stability of a relatively weak network after a grid fault is affected by the connection of a large wind park. A theoretical discussion of the stationary and dynamic characteristics of the Short Circuit Induction Generator and the Doubly...... of the network and saturation of the external reactive power compensation units provides a good basis for evaluation of the voltage stability. For the DFIG it is concluded that the speed stability limit is mainly determined by the voltage limitation of the rotor converter...

  3. Reactive Power Sharing and Voltage Harmonic Distortion Compensation of Droop Controlled Single Phase Islanded Microgrids

    DEFF Research Database (Denmark)

    Micallef, Alexander; Apap, Maurice; Spiteri-Staines, Cyril

    2014-01-01

    When paralleling multiple inverters that are capable of operating as an island, the inverters typically employ the droop control scheme. Traditional droop control enables the decentralized regulation of the local voltage and frequency of the microgrid by the inverters. The droop method also enables...... and reduction of the voltage harmonic distortion at the point of common coupling (PCC). Experimental results were then presented to show the suitability of the proposed algorithms in achieving reactive power sharing and in improving the voltage harmonic distortion at the PCC....

  4. 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.

  5. Instantaneous characteristics simulation and analysis on three-level brushless AC synchronous generators of aeronautic constant speed and frequency AC power system

    Science.gov (United States)

    Ma, Xiaohe; Shen, Songhua

    2006-11-01

    This paper mainly introduces theoretical analysis and experimental results of instantaneous characteristics on a certain three level brushless three-phase AC synchronous generators. The analysis, modeling and simulations with Simplorer software of Ansoft Company are carried out. It establishes three level generator models, gives theoretical relation matrix equation, and simulates some instantaneous characteristics. Design of the system requires reliable simulation tools with comprehensive component libraries capable of dealing with complex system behavior. The simulation results verify that the proposed system model can efficiently simulate the instantaneous characteristics of the real AC generator system. It gives better design experiences and digital methods for aeronautic constant speed and frequency AC power system.

  6. A nonlinear optimization approach for UPFC power flow control and voltage security

    Science.gov (United States)

    Kalyani, Radha Padma

    This dissertation provides a nonlinear optimization algorithm for the long term control of Unified Power Flow Controller (UPFC) to remove overloads and voltage violations by optimized control of power flows and voltages in the power network. It provides a control strategy for finding the long term control settings of one or more UPFCs by considering all the possible settings and all the (N-1) topologies of a power network. Also, a simple evolutionary algorithm (EA) has been proposed for the placement of more than one UPFC in large power systems. In this publication dissertation, Paper 1 proposes the algorithm and provides the mathematical and empirical evidence. Paper 2 focuses on comparing the proposed algorithm with Linear Programming (LP) based corrective method proposed in literature recently and mitigating cascading failures in larger power systems. EA for placement along with preliminary results of the nonlinear optimization is given in Paper 3.

  7. Approach to unbalance power active compensation under linear load unbalances and fundamental voltage asymmetries

    Energy Technology Data Exchange (ETDEWEB)

    Segui-Chilet, S.; Gimeno-Sales, F.J.; Orts, S.; Alcaniz, M.; Masot, R. [Instituto de Tecnologia Electrica - Grupo de Tecnologia Electronica, Universidad Politecnica de Valencia, Camino de Vera 14, 46022 Valencia (Spain); Garcera, G.; Figueres, E. [Departamento de Ingenieria Electronica, Universidad Politecnica de Valencia, Camino de Vera s/n, 46022 Valencia (Spain)

    2007-09-15

    This paper proposes a new definition of the unbalance power that allows the selective compensation of inefficiencies caused by linear loads by means of a three-phase shunt active power compensator (APC). Symmetrical components of current and voltage are used to evaluate the unbalance power in these systems and to define the compensating currents. The instantaneous power flows with unbalanced linear loads connected to a three-phase electrical system are analyzed following the normal procedure used for the quantification of the reactive power. Equations to calculate the unbalance power and the effective apparent power are obtained from the analysis of the instantaneous power flows. The output currents of the selective APC are defined using the instantaneous unbalance power approach. Power quantities and APC compensating current are defined for IEEE Std. 1459 and for the instantaneous unbalance power approach. Two examples are used to compare the power quantities and the APC operation. The main effects of unbalanced linear load and of fundamental voltage asymmetries are analyzed. Simulations of a shunt APC emphasize the advantages of the calculation of the compensating currents based on the proposed instantaneous unbalance power approach. A comparison with the results obtained by calculation of the compensating currents based on IEEE Std. 1459 is carried out. A new power factor is also defined and compared with other conventional definitions. (author)

  8. Design of Low Voltage Low Power CMOS OP-AMP

    Directory of Open Access Journals (Sweden)

    Shahid Khan,

    2014-11-01

    Full Text Available Operational amplifiers are an integral part of many analog and mixed signal systems. As the demand for mixed mode integrated circuits increases, the design of analog circuits such as operational amplifiers in CMOS technology becomes more critical. This paper presents a two stage CMOS operational amplifier, which operates at ±1.8V power supply using TSMC 0.18um CMOS technology. The OP-AMP designed exhibit unity gain frequency of 12.6 MHz, and gain of 55.5db with 300uw power dissipation. The gain margin and phase margin of OP-AMP is 45˚ and 60˚ respectively. Design and simulation has been carried out in P Spice tool.

  9. The prediction and prevention of voltage collapse in the Finnish power system

    Energy Technology Data Exchange (ETDEWEB)

    Bastman, J.; Lakervi, E. [Tampere Univ. of Tech. (Finland); Hirvonen, R.; Kuronen, P.; Hagman, E. [IVO Group (Finland)

    1994-12-31

    The Finnish power system is a part of the Nordic power system (NORDEL), which includes Finland, Sweden, Norway and the eastern part of Denmark. In NORDEL the transmission distances are long, which implies that the power transmission capacities are determined by stability criteria . The methods to prevent and predict the voltage collapse during severe disturbances are studied using advances simulation program. Results are presented. (author) 10 figs., 1 tab.

  10. Development of a method to evaluate shared alternate AC power source effects in multi-unit nuclear power plants

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Woo Sik; Yang, Joon Eun

    2003-07-01

    In order to evaluate accurately a Station BlackOut (SBO) event frequency of a multi-unit nuclear power plant that has a shared Alternate AC (AAC) power source, an approach has been developed which accommodates the complex inter-unit behavior of the shared AAC power source under multi-unit Loss Of Offsite Power (LOOP) conditions. The approach is illustrated for two cases, 2 units and 4 units at a single site, and generalized for a multi-unit site. Furthermore, the SBO frequency of the first unit of the 2-unit site is quantified. The SBO frequency at a target unit of Probabilistic Safety Assessment (PSA) could be underestimated if the inter-unit dependency of the shared AAC power source is not properly modeled. The effect of the inter-unit behavior of the shared AAC power source on the SBO frequency is not negligible depending on the Common Cause Failure (CCF) characteristics among AC power sources. The methodology suggested in the present report is believed to be very useful in evaluating the SBO frequency and the core damage frequency resulting from the SBO event. This approach is also applicable to the probabilistic evaluation of the other shared systems in a multi-unit nuclear power plant.

  11. Differential Evolution approach to Optimal Reactive Power Dispatch with Voltage Stability enhancement by Modal Analysis

    Directory of Open Access Journals (Sweden)

    J.Jithendranath

    2013-07-01

    Full Text Available This paper presents an evolutionary based algorithm for solving optimal reactive power dispatch problem in power system. The problem was designed as a Multi-Objective case with loss minimization and voltage stability as objectives. Generator terminal voltages, tap setting of transformers and reactive power generation of capacitor banks were taken as optimization variables. Modal analysis method is adopted to assess the voltage stability of system. The above presented problem was solved on basis of efficient and reliable technique among all evolutionary based algorithms, the Differential Evolution Technique. The proposed method has been tested on IEEE 30 bus system where the obtained results were found satisfactorily to a large extent that of reported earlier.

  12. Distributed Optimal Control of Reactive Power and Voltage in Islanded Microgrids

    DEFF Research Database (Denmark)

    Wang, Yanbo; Wang, Xiongfei; Chen, Zhe

    2017-01-01

    This paper presents a distributed optimal control strategy for islanded microgrids, which allows to perform reactive power sharing and voltage regulation without using communication system. To perform the twofold objectives, a small signal model is first developed to reconstruct the system input...... performance of the optimal controller is analyzed, from which the guideline for choosing controller parameters is formulated. The results obtained from sensitivity analysis, simulations and experiments show that the proposed approach provides the expected reliability and flexibility for optimizing......-output relationship, which is evaluated through sensitivity analysis. A state estimator is then constructed to observe reactive power distribution and system voltages by local measurement. An optimal regulator is developed to perform both reactive power sharing and system voltage restoration. And the dynamic...

  13. Distributed Optimal Control of Reactive Power and Voltage in Islanded Microgrids

    DEFF Research Database (Denmark)

    Wang, Yanbo; Wang, Xiongfei; Chen, Zhe

    2016-01-01

    The paper proposes a distributed optimal control strategy for islanded microgrids, which allows to perform reactive power sharing and voltage regulation without communication system. To realize the twofold objective, an improved small signal model is developed first to reconstruct the system input...... power sharing and system voltage restoration. And the dynamic performance of the optimal controller is analyzed, from which the guideline for choosing controller parameters is formulated. The results obtained from sensitivity analysis, simulations and experiments show that the proposed approach provides......-output relationship, where the relationship is evaluated with sensitivity analysis. A state estimator is then constructed based on the new input-output relationship in order to observe reactive power distribution and system voltages by local measurement. An optimal regulator is developed to perform both reactive...

  14. The Current-voltage Characteristics Simulation of the Betavoltaic Power Supply

    Directory of Open Access Journals (Sweden)

    S.U. Urchuk

    2015-12-01

    Full Text Available In order to optimize betavoltaic power supply it was calculated the current-voltage characteristics when changing the depth of the upper p-layer and at changing doping levels structure areas. It is shown that an increase in the depth reduces the short-circuit current and thus reduces the open circuit voltage. It has been observed that the concentration of the lightly doped region more significantly influence on the current-voltage characteristics than the depth of the p-n-junction. The concentration of the n-region, equal to 1014 cm – 3, can be considered as during betavoltaic power supply design. It is shown that, by increasing the power supply activity the conversion efficiency of the structure increases, too.

  15. False Operation of Static Random Access Memory Cells under Alternating Current Power Supply Voltage Variation

    Science.gov (United States)

    Sawada, Takuya; Takata, Hidehiro; Nii, Koji; Nagata, Makoto

    2013-04-01

    Static random access memory (SRAM) cores exhibit susceptibility against power supply voltage variation. False operation is investigated among SRAM cells under sinusoidal voltage variation on power lines introduced by direct RF power injection. A standard SRAM core of 16 kbyte in a 90 nm 1.5 V technology is diagnosed with built-in self test and on-die noise monitor techniques. The sensitivity of bit error rate is shown to be high against the frequency of injected voltage variation, while it is not greatly influenced by the difference in frequency and phase against SRAM clocking. It is also observed that the distribution of false bits is substantially random in a cell array.

  16. Design of Multi-unit Control System of High Voltage Power Supply for LASCAR Scintillator Detector Array

    Institute of Scientific and Technical Information of China (English)

    WuLijie; WangJinchuan; XiaoGuoqing; GuoZhongyan; ZhanWenlong; QiHuirong; XuZhiguo; ZhangLi; DingXianli; XuHushan; SunZhiyu; LiJiaxing; LiChen; WangMeng; ChenLixin; HuZhengguo; MaoRuishi; ZhaoTiecheng

    2003-01-01

    The power voltages of Photomultipliers (PMTs) at RIBLL LASCAR scintillator detector array are distributed between 900 V and 1 800 V irregularly. 392 CC123 modules are employed to supply high voltage for the PMT array. The CC123 module serves as PMT interface groupware package, and it can transform +12 V DC input voltage to ranges of 0~-2200 V for the PMT power supply corresponding to 0~+5 V output voltage from the control board crate. The relation of PMT power supply with the output voltage of the control crate is shown in Fig.1.

  17. Distributed Operation of Interlinked AC Microgrids with Dynamic Active and Reactive Power Tuning

    DEFF Research Database (Denmark)

    Nutkani, Inam Ullah; Loh, Poh Chiang; Blaabjerg, Frede

    2013-01-01

    Microgrids are small grids formed by clustering modern generating sources, storage systems, and loads together. Being independent, the formed microgrids can, in principle, operate at their own preferred voltages and frequencies. Tying them to the mains grid or another microgrid would therefore...... require some interlinking power converters, whose control should preferably be autonomous without depending on fast communication links. Contributing to this theme of research, a distributed power management scheme has been proposed in this paper for interlinking two or more independent microgrids...... operating at different voltages and frequencies. The proposed scheme allows sources in the microgrids to concentrate more on active power harnessing, while the interlinking converters focus more on meeting the load reactive demand. If necessary, backup active power from an underloaded microgrid can also...

  18. A dual-mode phase-shift modulation control scheme for voltage multiplier based X-ray power supply

    Energy Technology Data Exchange (ETDEWEB)

    Iqbal, S [School of Electrical and Electronics Engineering, University Sains Malaysia, 14300 Nibong Tebal, Pulau Pinang (Malaysia); Besar, R; Venkataseshaiah, C, E-mail: shahidsidu@hotmail.co [Faculty of Engineering and Technology, Multimedia University, 75450 Melaka (Malaysia)

    2010-05-15

    This paper proposes a dual-mode phase-shift modulation control scheme for series resonant inverter fed voltage multiplier (VM) based X-ray power supply. In this control scheme the outputs voltage of two parallel connected series resonant inverters are mixed before supplying to VM circuit. The output voltage of the power supply is controlled by varying the phase-shift between the output voltages of two inverters. In order to achieve quick rise of output voltage, the power supply is started with zero phase-shift and as the output voltage reaches 90% of the target voltage, the phase-shift is increased to a value which corresponds to target output voltage to prevent overshoot. The proposed control scheme has been shown to have good performance. Experimental results based on the scaled-down laboratory prototype are presented to validate the effectiveness of proposed dual-mode phase shift modulation control scheme.

  19. Reactive Power Compensation of a 24 MW Wind Farm using a 12-Pulse Voltage Source Converter

    DEFF Research Database (Denmark)

    Pedersen, Knud Ole Helgesen; Pedersen, Jørgen Kaas

    1998-01-01

    Integration of large wind farms in distribution and transmission systems may have severe influence on the power quality at the connection point and may also influence the voltage controlling capability of the electrical system. The purpose of the described project has been to develop and investig......Integration of large wind farms in distribution and transmission systems may have severe influence on the power quality at the connection point and may also influence the voltage controlling capability of the electrical system. The purpose of the described project has been to develop...... and investigate the use of a STATCOM by modelling and field testing an 8 MVar unit in a 24 MW wind farm....

  20. A Reduced-Part, Triple-Voltage DC-DC Converter for Electric Vehicle Power Management

    Energy Technology Data Exchange (ETDEWEB)

    Su, Gui-Jia [ORNL; Tang, Lixin [ORNL

    2007-01-01

    Electrical power systems in future hybrid and fuel cell vehicles may consist of three voltage nets; 14 V, 42 V and high voltage (>200 V) buses. A soft-switched, bi-directional dc-dc converter using only four switches was proposed for interconnecting the three nets. This paper presents a reduced- part dc-dc converter, which decreases the converter cost while retaining all the favorable features of the original topology. Simulation and experimental data are included to verify a simple power flow control scheme.