WorldWideScience

Sample records for voltage sag source

  1. 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.

  2. Mitigation of Voltage Sags in CIGRE Low Voltage Distribution Network

    DEFF Research Database (Denmark)

    Mustafa, Ghullam; Bak-Jensen, Birgitte; Mahat, Pukar

    2013-01-01

    Any problem in voltage in a power network is undesirable as it aggravates the quality of the power. Power electronic devices such as Voltage Source Converter (VSC) based Static Synchronous Compensator (STATCOM), Dynamic Voltage Restorer (DVR) etc. are commonly used for the mitigation of voltage p....... The compensation of voltage sags in the different parts of CIGRE distribution network is done by using the four STATCOM compensators already existing in the test grid. The simulations are carried out in DIgSILENT power factory software version 15.0.......Any problem in voltage in a power network is undesirable as it aggravates the quality of the power. Power electronic devices such as Voltage Source Converter (VSC) based Static Synchronous Compensator (STATCOM), Dynamic Voltage Restorer (DVR) etc. are commonly used for the mitigation of voltage...... problems in the distribution system. The voltage problems dealt with in this paper are to show how to mitigate voltage sags in the CIGRE Low Voltage (LV) test network and networks like this. The voltage sags, for the tested cases in the CIGRE LV test network are mainly due to three phase faults...

  3. Mitigation of voltage sags in the distribution system with dynamic voltage restorer

    International Nuclear Information System (INIS)

    Viglas, D.; Belan, A.

    2012-01-01

    Dynamic voltage restorer is a custom power device that is used to improve voltage sags or swells in electrical distribution system. The components of the Dynamic Voltage Restorer consist of injection transformers, voltage source inverter, passive filters and energy storage. The main function of the Dynamic voltage restorer is used to inject three phase voltage in series and in synchronism with the grid voltages in order to compensate voltage disturbances. This article deals with mitigation of voltage sags caused by three-phase short circuit. Dynamic voltage restorer is modelled in MATLAB/Simulink. (Authors)

  4. Allocation of Load-Loss Cost Caused by Voltage Sag

    Science.gov (United States)

    Gao, X.

    2017-10-01

    This paper focuses on the allocation of load-loss cost caused by voltage sag in the environment of electricity market. To compensate the loss of loads due to voltage sags, the load-loss cost is allocated to both sources and power consumers. On the basis of Load Drop Cost (LDC), a quantitative evaluation index of load-loss cost caused by voltage sag is identified. The load-loss cost to be allocated to power consumers themselves is calculated according to load classification. Based on the theory of power component the quantitative relation between sources and loads is established, thereby a quantitative calculation method for load-loss cost allocated to each source is deduced and the quantitative compensation from individual source to load is proposed. A simple five-bus system illustrates the main features of the proposed method.

  5. Research on uncertainty evaluation measure and method of voltage sag severity

    Science.gov (United States)

    Liu, X. N.; Wei, J.; Ye, S. Y.; Chen, B.; Long, C.

    2018-01-01

    Voltage sag is an inevitable serious problem of power quality in power system. This paper focuses on a general summarization and reviews on the concepts, indices and evaluation methods about voltage sag severity. Considering the complexity and uncertainty of influencing factors, damage degree, the characteristics and requirements of voltage sag severity in the power source-network-load sides, the measure concepts and their existing conditions, evaluation indices and methods of voltage sag severity have been analyzed. Current evaluation techniques, such as stochastic theory, fuzzy logic, as well as their fusion, are reviewed in detail. An index system about voltage sag severity is provided for comprehensive study. The main aim of this paper is to propose thought and method of severity research based on advanced uncertainty theory and uncertainty measure. This study may be considered as a valuable guide for researchers who are interested in the domain of voltage sag severity.

  6. Macroeconomic Assessment of Voltage Sags

    Directory of Open Access Journals (Sweden)

    Sinan Küfeoğlu

    2016-12-01

    Full Text Available The electric power sector has changed dramatically since the 1980s. Electricity customers are now demanding uninterrupted and high quality service from both utilities and authorities. By becoming more and more dependent on the voltage sensitive electronic equipment, the industry sector is the one which is affected the most by voltage disturbances. Voltage sags are one of the most crucial problems for these customers. The utilities, on the other hand, conduct cost-benefit analyses before going through new investment projects. At this point, understanding the costs of voltage sags become imperative for planning purposes. The characteristics of electric power consumption and hence the susceptibility against voltage sags differ considerably among different industry subsectors. Therefore, a model that will address the estimation of worth of electric power reliability for a large number of customer groups is necessary. This paper introduces a macroeconomic model to calculate Customer Voltage Sag Costs (CVSCs for the industry sector customers. The proposed model makes use of analytical data such as value added, annual energy consumption, working hours, and average outage durations and provides a straightforward, credible, and easy to follow methodology for the estimation of CVSCs.

  7. Mitigation of Unbalanced Voltage Sags and Voltage Unbalance in CIGRE Low Voltage Distribution Network

    DEFF Research Database (Denmark)

    Mustafa, Ghullam; Bak-Jensen, Birgitte; Mahat, Pukar

    2013-01-01

    Any problem with voltage in a power network is undesirable as it aggravates the quality of the power. Power electronic devices such as Voltage Source Converter (VSC) based Static Synchronous Compensator (STATCOM) etc. can be used to mitigate the voltage problems in the distribution system...... to unbalanced faults. The compensation of unbalanced voltage sags and voltage unbalance in the CIGRE distribution network is done by using the four STATCOM compensators already existing in the test grid. The simulations are carried out in DIgSILENT power factory software version 15.0........ The voltage problems dealt with in this paper are to show how to mitigate unbalanced voltage sags and voltage unbalance in the CIGRE Low Voltage (LV) test network and net-works like this. The voltage unbalances, for the tested cases in the CIGRE LV test network are mainly due to single phase loads and due...

  8. An Estimation Method of System Voltage Sag Profile using Recorded Sag Data

    Science.gov (United States)

    Tanaka, Kazuyuki; Sakashita, Tadashi

    The influence of voltage sag to electric equipment has become big issues because of wider utilization of voltage sensitive devices. In order to reduce the influence of voltage sag appearing at each customer side, it is necessary to recognize the level of receiving voltage drop due to lightning faults for transmission line. However it is hard to measure directly those sag level at every load node. In this report, a new method of efficiently estimating system voltage sag profile is proposed based on symmetrical coordinate. In the proposed method, limited recorded sag data is used as the estimation condition which is recorded at each substation in power systems. From the point of view that the number of the recorded node is generally far less than those of the transmission route, a fast solution method is developed to calculate only recorder faulted voltage by applying reciprocity theorem for Y matrix. Furthermore, effective screening process is incorporated, in which the limited candidate of faulted transmission line can be chosen. Demonstrative results are presented using the IEEJ East10 standard system and actual 1700 bus system. The results show that estimation accuracy is sufficiently acceptable under less computation labor.

  9. Current source converter based D-STATCOM for voltage sag mitigation

    Directory of Open Access Journals (Sweden)

    Singh Moirangthem Deben

    2015-01-01

    Full Text Available This paper presents a novel method of realizing one of the custom power controllers, the distribution static synchronous compensator (D-STATCOM using current source converter (CSC topology. Almost all the custom power controllers such as dynamic voltage restorer (DVR, unified power quality conditioner (UPQC including D-STATCOM are generally designed and implemented by using voltage source converters (VSC and not much research publications with CSC based approach has been reported over the last one decade. Since the D-STATCOM is a current injection device, its performance can be improved when realized by a current-source converter which can generate a controllable current directly at its output terminals and offers many advantageous features. In this paper, an attempt has been made to study the performance of a CSC based D-STATCOM suitable for use in the power distribution system in order to mitigate voltage sag and improve power quality. The proposed model uses a three leg CSC whose switching strategy is based on sinusoidal pulse width modulation (SPWM. The model has been simulated in the Matlab/Simulink environment. The results of the simulation runs under steady state and dynamic load perturbation provide excellent voltage and current waveforms that support the justification of the proposed model.

  10. Energy Storage Characteristic Analysis of Voltage Sags Compensation for UPQC Based on MMC for Medium Voltage Distribution System

    Directory of Open Access Journals (Sweden)

    Yongchun Yang

    2018-04-01

    Full Text Available The modular multilevel converter (MMC, as a new type of voltage source converter, is increasingly used because it is a distributed storage system. There are many advantages of using the topological structure of the MMC on a unified power quality controller (UPQC, and voltage sag mitigation is an important use of the MMC energy storage system for the power quality compensation process. In this paper, based on the analysis of the topology of the MMC, the essence of energy conversion in a UPQC of voltage sag compensation is analyzed; then, the energy storage characteristics are calculated and analyzed to determine the performance index of voltage sag compensation; in addition, the simulation method is used to verify the voltage sag compensation characteristics of the UPQC; finally, an industrial prototype of the UPQC based on an MMC for 10 kV of medium voltage distribution network has been developed, and the basic functions of UPQC have been tested.

  11. A new approach to voltage sag detection based on wavelet transform

    Energy Technology Data Exchange (ETDEWEB)

    Gencer, Oezguer; Oeztuerk, Semra; Erfidan, Tarik [Kocaeli University, Faculty of Engineering, Department of Electrical Engineering, Veziroglu Kampuesue, Eski Goelcuek Yolu, Kocaeli (Turkey)

    2010-02-15

    In this work, a new voltage sag detection method based on wavelet transform is developed. Voltage sag detection algorithms, so far have proved their efficiency and computational ability. Using several windowing techniques take long computational times for disturbance detection. Also researchers have been working on separating voltage sags from other voltage disturbances for the last decade. Due to increasing power quality standards new high performance disturbance detection algorithms are necessary to obtain high power quality standards. For this purpose, the wavelet technique is used for detecting voltage sag duration and magnitude. The developed voltage sag detection algorithm is implemented with high speed microcontroller. Test results show that, the new approach provides very accurate and satisfactory voltage sag detection. (author)

  12. Voltage sags impact on CAR and SOR of HANARO

    International Nuclear Information System (INIS)

    Kim, Hyung Kyoo; Jung, Hoan Sung; Wu, Jong Sup

    2004-01-01

    The combination of the unstable electric power and sensitive equipment may cause the nuisance of reactor trip. The reactor is tripped by the RRS and RPS during the occurrence of the voltage sags or momentary interruptions. We tested the components of RRS and RPS for the immunity from voltage sags and momentary interruptions. The tested components are DC power supply for CAR (control absorbed rod) of RRS and AC coil contactor for SOR (shut off rod) of RPS. We briefly describe the power quality standard for the voltage sags. This paper summarizes the magnitudes and durations of the voltage sags which impact on the CAR and SOR system

  13. Responsive demand to mitigate slow recovery voltage sags

    DEFF Research Database (Denmark)

    Garcia-Valle, Rodrigo; da Silva, Luiz Carlos Pereira; Xu, Zhao

    2012-01-01

    , and reactive power reserve for peak load management through price responsive methods and also as energy providers through embedded generation technologies. This article introduces a new technology, called demand as voltagecontrolled reserve, which can help mitigation of momentary voltage sags. The technology...... faults. This article presents detailed models, discussion, and simulation tests to demonstrate the technical viability and effectiveness of the demand as voltage-controlled reserve technology for mitigating voltage sags....... can be provided by thermostatically controlled loads as well as other types of load. This technology has proven to be effective in distribution systems with a large composition of induction motors, when voltage sags present slow recovery characteristics because of the deceleration of the motors during...

  14. Voltage sags: Their impact on the utility and industrial customers

    International Nuclear Information System (INIS)

    Davis, T.; Beam, G.E.; Melhorn, C.J.

    1995-01-01

    This paper describes the impact of voltage sags on the utility and industrial customers. Several utility measures are presented to minimize the customer's exposure to voltage sags. However, these measures cannot completely eliminate the impact of voltage sags on sensitive equipment. A case study is presented in this paper that includes measurement results that were used to characterize the voltage sags experienced on the utility system and in the industrial facility, simulation results that were used to develop area of vulnerability curves for the industrial facility, mitigation equipment that was employed to improve the sensitive equipment's ride through capability, and the lessons learned from the systems approach analysis

  15. Voltage Sag due to Pollution Induced Flashover Across Ceramic Insulator Strings

    Science.gov (United States)

    Reddy B, Subba; Goswami, Arup Kumar

    2017-11-01

    Voltage sag or voltage dips are significant to industrial reliability. There is a necessity to characterize the feeder level power quality (PQ) and the PQ performance among various utility companies. Contamination/pollution induced flashover is the ultimate consequence of the creeping discharges across the insulator strings which induce voltage sag. These have a severe threat on the safe and reliable operation of power systems. In the present work an attempt has been made to experimentally investigate the occurrence of voltage sag/dips during pollution induced flashovers. Results show significant dip/sag in the voltage magnitude during the flashover process.

  16. Advanced Control of the Dynamic Voltage Restorer for Mitigating Voltage Sags in Power Systems

    Directory of Open Access Journals (Sweden)

    Dung Vo Tien

    2018-01-01

    Full Text Available The paper presents a vector control with two cascaded loops to improve the properties of Dynamic Voltage Restorer (DVR to minimize Voltage Sags on the grid. Thereby, a vector controlled structure was built on the rotating dq-coordinate system with the combination of voltage control and the current control. The proposed DVR control method is modelled using MATLAB-Simulink. It is tested using balanced/unbalanced voltage sags as well as fluctuant and distorted voltages. As a result, by using this controlling method, the dynamic characteristics of the system have been improved significantly. The system performed with higher accuracy, faster response and lower distortion in the voltage sags compensation. The paper presents real time experimental results to verify the performance of the proposed method in real environments.

  17. Modelling voltage sag mitigation using dynamic voltage restorer and analyzing power quality issue

    Science.gov (United States)

    Ismail, Nor Laili; Hidzir, Hizrin Dayana Mohd; Thanakodi, Suresh; Nazar, Nazatul Shiema Moh; Ibrahim, Pungut; Ali, Che Ku Muhammad Sabri Che Ku

    2018-02-01

    Power quality problem which are arise due to a fault or a pulsed load can have caused an interruption of critical load. The modern power systems are becoming more sensitive to the quality of the power supplied by the utility company. Voltage sags and swells, flicker, interruptions, harmonic distortion and other distortion to the sinusoidal waveform are the examples of the power quality problems. The most affected due to these problems is industrial customers who use a lot of sensitive equipment. There has suffered a huge loss to these problems. Resulting of broken or damage equipment if voltage sag exceeds the sensitive threshold of the equipment. Thus, device such as Static Synchronous Compensator (STATCOM) and Dynamic Voltage Restorer (DVR) has been created to solve this problem among users. DVR is a custom power device that most effective and efficient. This paper intended to report the DVR operations during voltage sag compensation.

  18. Effects of balanced and unbalanced voltage sags on DC adjustable-speed drives

    Energy Technology Data Exchange (ETDEWEB)

    Pedra, Joaquin; Sainz, Luis; Corcoles, Felipe; Bergas, Joan [Department of Electrical Engineering, ETSEIB-UPC, Av. Diagonal, 647, 08028 Barcelona (Spain); de Blas, Alfredo [Department of Electrical Engineering, EUETIB-UPC, C. d' Urgell, 187, 08036 Barcelona (Spain)

    2008-06-15

    This paper analyzes the sensitivity of DC adjustable-speed drives to balanced and unbalanced voltage sags. The influence of sag type, depth, duration and phase-angle jump on DC drives is studied. The control of the DC drive has been taken into account to understand drive behavior in the presence of voltage sags. Two working modes of the DC motor are considered in the study: as a consumer load and as a regenerative load. When the DC motor works as a consumer load, the study shows that sag type and depth have a significant influence on drive behavior. However, the voltage sag can be ridden through if the rectifier firing angle is set correctly by the control. When the DC motor works as a regenerative load, the study shows the consequences of the three-phase rectifier commutation failure due to the voltage sag. (author)

  19. Effects of symmetrical voltage sags on squirrel-cage induction motors

    Energy Technology Data Exchange (ETDEWEB)

    Pedra, Joaquin; Sainz, Luis; Corcoles, Felipe [Department of Electrical Engineering, ETSEIB-UPC, Av. Diagonal, 647, 08028 Barcelona (Spain)

    2007-10-15

    This paper analyzes the symmetrical voltage sag consequences on the induction motor behavior when single- and double-cage models are considered, namely current and torque peaks, and speed loss. These effects depend on several variables like sag type, duration and depth. Voltage sag effects are studied by using single- and double-cage models for three motors of different rated power. The double-cage model always predicts torque and current peaks higher than those of the single-cage model. The single-cage model predicts that voltage sags can produce motor instability, whereas the double-cage model is always stable. Therefore, the double-cage model must be used for the simulation of the squirrel-cage induction motor, because the single-cage model can give erroneous results in some situations. (author)

  20. Voltage Sag Compensator for CAR and SOR of HANARO

    International Nuclear Information System (INIS)

    Kim, Hyung-Kyoo; Jung, Hoan-Sung; Wu, Jong-Sup

    2007-01-01

    HANARO is designed so as to be tripped automatically by insertion of control absorber rods(CAR) and shut-off rods(SOR) and the process systems, such as primary cooling system, secondary cooling system and reflector cooling system, etc., stop whenever the off-site power failure occurs, the reactor trips automatically. When voltage sag or momentary interruption occurs, the process systems are in operation but the reactor has an unwanted trip by insertion of CARs and SORs. We installed the voltage sag compensator on the power supply for CARs and SORs so as to prevent a nuisance trip. The compensated time is decided not to exceed 1 sec in consideration of reactor safety. This paper is concerned with the impact of the momentary interruption on the reactor and the effect of the voltage sag compensator

  1. SVC or VSC for reduction of voltage sags and flicker. Trends in power electronics

    Energy Technology Data Exchange (ETDEWEB)

    Haeusler, M; Schnettler, A [ABB Calor Emag Schaltanlagen AG, Mannheim (Germany); Halvarsson, P [ABB Power Systems AB, Vaesteraas (Sweden)

    1997-07-01

    In the past complaints about insufficient power quality were often caused by flicker observed in the neighbourhood of industrial networks. Voltage sags due to faults in the power system pass, however, mostly unnoticed as not-so-common events. Now electronic controls are penetrating more and more in industry. Electronic controllers on factory machines - particularly those for variable speed motors - are vulnerable to voltage sags. A one-tenth second sag can cause a $200.000 downtime incident in a big factory. Therefore the demands on power quality are rising in industry as well. The costly separation in clean networks for residential areas and dirty networks for industrial grids is no perfect solution to avoid such problems. Static VAr Compensators (SVC) are traditionally one means to control the voltage in industrial networks. Because of the recent development of powerful gate turn-off semiconductor devices another type of converter has gained new interest for mitigation of system disturbances, the voltage-source converter (VSC). The characteristics of both types of power electronics in view of their possibilities for this application are presented. (orig.)

  2. The influence of transformers, induction motors and fault resistance regarding propagation voltage sags

    OpenAIRE

    Jairo Blanco; Ruben Darío Leal; Jonathan Jacome; Johann F. Petit; Gabriel Ordoñez; Víctor Barrera

    2011-01-01

    This article presents an analysis of voltage sag propagation. The ATPDraw tool was selected for simulating the IEEE 34 node test feeder. It takes into account both voltage sags caused by electrical fault network, as well as voltage sag propagation characteristics caused by induction motor starting and transformer energising. The analysis was aimed at assessing the influence of transformer winding connections, the impedance of these transformers, lines and cables, summarising the...

  3. Multipurpose Compensation Scheme for Voltage Sag/Swell and Selective Harmonics Elimination in Distribution Systems

    Directory of Open Access Journals (Sweden)

    Mustafa Inci

    2018-01-01

    Full Text Available Voltage harmonics, sag, and swell are the most harmful disturbances in distribution systems. This paper introduces a novel effective controller method for simultaneous compensation of both voltage sag/swell and voltage harmonics by using multifunctional dynamic voltage restorer. In proposed controller method called FFT with integrated ISRF, ISRF detects the magnitudes of voltage sag/swell quickly and precisely, and FFT extracts the selective components of voltage harmonics very effectively. The proposed method integrates the superior properties of ISRF and FFT methods. FFT integrated ISRF is applied for the first time to provide the compensation of both sag/swell and selective harmonics together. The proposed system has ability to compensate symmetrical/asymmetrical sag/swell and symmetrical/asymmetrical selective harmonics which are 5th, 7th, 11th and 13th. The controlled system is modelled in PSCAD/EMDTC and compared with conventional methods. The performance results verify that the proposed method compensates voltage disturbances effectively in the system.

  4. An impact analysis of the fault impedance on voltage sags

    Energy Technology Data Exchange (ETDEWEB)

    Ramos, Alessandro Candido Lopes [CELG - Companhia Energetica de Goias, Goiania, GO (Brazil). Generation and Transmission. System' s Operation Center], E-mail: alessandro.clr@celg.com.br; Batista, Adalberto Jose [Federal University of Goias (UFG), Goiania, GO (Brazil)], E-mail: batista@eee.ufg.br; Leborgne, Roberto Chouhy [Federal University of Rio Grande do Sul (UFRGS), Porto Alegre, RS (Brazil)], E-mail: rcl@ece.ufrgs.br; Emiliano, Pedro Henrique Mota, E-mail: ph@phph.com.br

    2009-07-01

    This paper presents an impact analysis of the fault impedance, in terms of its module and angle, on voltage sags caused by faults. Symmetrical and asymmetrical faults are simulated, at transmission and distribution lines, by using a frequency-domain fault simulation software called ANAFAS. Voltage sags are monitored at buses where sensitive end-users are connected. In order to overcome some intrinsic limitations of this software concerning its automatic execution for several cases, a computational tool was developed in Java programming language. This solution allows the automatic simulation of cases including the effect of the fault position, the fault type, and the proper fault impedance. The main conclusion is that the module and angle of the fault impedance can have a significant influence on voltage sag depending on the fault characteristics. (author)

  5. A robust and fast generic voltage sag detection technique

    DEFF Research Database (Denmark)

    L. Dantas, Joacillo; Lima, Francisco Kleber A.; Branco, Carlos Gustavo C.

    2015-01-01

    In this paper, a fast and robust voltage sag detection algorithm, named VPS2D, is introduced. Using the DSOGI, the algorithm creates a virtual positive sequence voltage and monitories the fundamental voltage component of each phase. After calculating the aggregate value in the o:;3-reference fram...

  6. Early Prediction of Transient Voltage Sags caused by Rotor Swings

    DEFF Research Database (Denmark)

    Weckesser, Johannes Tilman Gabriel; Jóhannsson, Hjörtur; Van Cutsem, Thierry

    2014-01-01

    The paper investigates various methods to predict voltage sags at load buses caused by large generator rotor swings and following a transient disturbance. Three different prediction methods are proposed, which all use real-time measurements from PMUs. One of the methods uses a slightly extended v...... version of the E-SIME method. The other two methods use Measurements and process them by recursive least square estimation. It is shown that the prediction method employing E-SIME allows the earliest detection of a critical voltage sag with satisfactory accuracy....

  7. The influence of motor re-acceleration on voltage sags

    NARCIS (Netherlands)

    Bollen, M.H.J.

    1995-01-01

    The assumption that a voltage sag is rectangular is not correct in a power system with large induction motor loads. The motors decelerate during the short circuit. After fault-clearing, they will accelerate again, drawing a high reactive current from the supply, causing a prolonged postfault voltage

  8. 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...... of voltage sags is analyzed. Fault tolerant control algorithm was designed, implemented and is discussed. The fault conditions and their effects were investigated at different power levels....

  9. Analysis of doubly-fed induction machine operating at motoring mode subjected to voltage sag

    Directory of Open Access Journals (Sweden)

    Navneet Kumar

    2016-09-01

    Full Text Available Variable Speed (VS Pumped Storage Plants (PSP equipped with large asynchronous (Doubly-Fed Induction machines are emerging now in hydropower applications. Motoring mode of operation of Doubly-Fed Induction Machine (DFIM is essential and techno-economical in this application due to: (1 its uniqueness in active power controllability, (2 bulk power handing capability with less rated power converters in rotor circuit, and (3 integrating Renewable Energy Sources (RES. This paper investigates the performance of two DFIMs at different power ratings (2.2 kW and 2 MW under voltage sag with different attribute. The test results are analyzed in terms of the peaks in torque, speed, power taken and transient currents in rotor and stator circuits. During sag, stable region for DFIM operation along with speed and stator side reactive power input control is also illustrated. The negative effects of voltage sag are briefly discussed. MATLAB simulation is validated with experimentation. The various observations during simulation and experimental analysis are also supported by the theoretical explanations.

  10. Complete characterization of voltage sags: an alternative to achieve energy quality

    International Nuclear Information System (INIS)

    Zuniga Medina, Edgar Andres; Vasco Garcia, Carlos Andres

    1992-01-01

    In this paper, the meaning of the power quality and its negative influence in the automation processes are presented. Voltage sags, the problems they cause and a methodology to characterize the phenomenon are also presented. Once the problems associated with the different sensible loads connected to a power system are identified, the cause of the bad quality of the electrical energy provided those loads is then established; voltage sags are one of the most common phenomenon that requires characterization in order to diminish their negative impact on the industrial processes

  11. Doubly-Fed Induction Generator Control Under Voltage Sags

    DEFF Research Database (Denmark)

    Teodorescu, Remus; Blaabjerg, Frede; Lima, K.

    2008-01-01

    This paper proposes a new control technique to improve the fault-ride through capability of doubly fed induction generators (DFIG). In such generators the appearance of severe voltage sags at the coupling point make rise to high over currents at the rotor/stator windings, something that makes...

  12. A novel current mode controller for a static compensator utilizing Goertzel algorithm to mitigate voltage sags

    International Nuclear Information System (INIS)

    Najafi, E.; Yatim, A.H.M.

    2011-01-01

    Research highlights: → We proposed a new current control method for STATCOM. → The current control method maintains a fixed switching frequency. → It also produces fewer harmonics compared to conventional hysteresis method. → A new voltage dip (sag) detection method was used in STATCOM. → The control method can mitigate voltage sag in each phase separately. -- Abstract: Static compensator (STATCOM) has been widely proposed for power quality and network stability improvement. It is easily connected in parallel to the electric network and has many advantages for electrical grids. It can improve network stability; power factor, power transfer rating and can avoid some disturbances such as sags and swells. Most of STATCOM controllers are based on voltage controllers that are based on balanced d-q transform. However, they are not thorough solutions for network disturbances since in most cases single-phase disturbances occur in electrical networks that cannot be avoided by the conventional controllers. Voltage mode controllers are also not capable of responding fast enough to the changes expected of a network system. This paper proposes a new current mode controller to overcome the mentioned problem. The approach uses a fixed frequency current controller to maintain voltage levels in voltage sags (dips). This approach is also simple and can be easily implemented by digitally. It has superior performance over conventional methods in terms of harmonic reduction in STATCOM output current. Another important factor for STATCOM effectiveness in sag mitigation is its sag detection method. This paper also introduces a new sag detection method based on Goertzel algorithm which is both effective and simple for practical applications. The simulation results presented illustrate the superiority of the proposed controller and sag detection algorithm to be utilized in the STATCOM.

  13. Optimum distributed generation placement with voltage sag effect minimization

    International Nuclear Information System (INIS)

    Biswas, Soma; Goswami, Swapan Kumar; Chatterjee, Amitava

    2012-01-01

    Highlights: ► A new optimal distributed generation placement algorithm is proposed. ► Optimal number, sizes and locations of the DGs are determined. ► Technical factors like loss, voltage sag problem are minimized. ► The percentage savings are optimized. - Abstract: The present paper proposes a new formulation for the optimum distributed generator (DG) placement problem which considers a hybrid combination of technical factors, like minimization of the line loss, reduction in the voltage sag problem, etc., and economical factors, like installation and maintenance cost of the DGs. The new formulation proposed is inspired by the idea that the optimum placement of the DGs can help in reducing and mitigating voltage dips in low voltage distribution networks. The problem is configured as a multi-objective, constrained optimization problem, where the optimal number of DGs, along with their sizes and bus locations, are simultaneously obtained. This problem has been solved using genetic algorithm, a traditionally popular stochastic optimization algorithm. A few benchmark systems radial and networked (like 34-bus radial distribution system, 30 bus loop distribution system and IEEE 14 bus system) are considered as the case study where the effectiveness of the proposed algorithm is aptly demonstrated.

  14. Time-Domain Voltage Sag State Estimation Based on the Unscented Kalman Filter for Power Systems with Nonlinear Components

    Directory of Open Access Journals (Sweden)

    Rafael Cisneros-Magaña

    2018-06-01

    Full Text Available This paper proposes a time-domain methodology based on the unscented Kalman filter to estimate voltage sags and their characteristics, such as magnitude and duration in power systems represented by nonlinear models. Partial and noisy measurements from the electrical network with nonlinear loads, used as data, are assumed. The characteristics of voltage sags can be calculated in a discrete form with the unscented Kalman filter to estimate all the busbar voltages; being possible to determine the rms voltage magnitude and the voltage sag starting and ending time, respectively. Voltage sag state estimation results can be used to obtain the power quality indices for monitored and unmonitored busbars in the power grid and to design adequate mitigating techniques. The proposed methodology is successfully validated against the results obtained with the time-domain system simulation for the power system with nonlinear components, being the normalized root mean square error less than 3%.

  15. Performance Improvement of DFIG Wind Turbine Using Series Grid-Side Converter under Unbalanced Grid Voltage and Voltage Sag Conditions

    DEFF Research Database (Denmark)

    Shokri, Yunes; Ebrahimzadeh, Esmaeil; Lesani, Hamid

    2014-01-01

    under unbalanced grid voltage and small voltage sag conditions without needing additional DC link capacitor or energy storage unlike other methods. The control system includes negative and positive sequence controllers which make the stator voltage balanced and keep it constant at the nominal value...

  16. Simulation and experiment of a YBCO SMES prototype in voltage sag compensation

    International Nuclear Information System (INIS)

    Zhu Jiahui; Yuan Weijia; Coombs, T.A.; Ming, Q.

    2011-01-01

    Research highlights: → YBCO conductors are used in SMES. → The SMES is successfully used to compensate voltage sag by both simulation and experiment. → A new control strategy for the power converter in the SMES. - Abstract: This paper gives a introduction of a SMES unit using 2G HTS wires. A complete SMES system including both superconducting coils and control circuit has been designed to operate at 77 K. Three single-phase H-bridge converters have been used in the control circuit. A loop control signal is sent out by using 32 fixed point Digital Signal Processor (DSP). The complete circuit has been both modelled in simulation and built experimentally. The results validate that this SMES successfully compensates a voltage sag in a power system.

  17. Simulation and experiment of a YBCO SMES prototype in voltage sag compensation

    Energy Technology Data Exchange (ETDEWEB)

    Zhu Jiahui, E-mail: zhujiahui@epri.sgcc.com.c [China Electric Power Research Institute, No. 15 Xiaoying Rd(E), Qinghe, Beijing 100192 (China); Yuan Weijia; Coombs, T.A. [Electrical Engineering Division, Engineering Department, University of Cambridge, CB3 0FA (United Kingdom); Ming, Q. [China Electric Power Research Institute, No. 15 Xiaoying Rd(E), Qinghe, Beijing 100192 (China)

    2011-03-15

    Research highlights: {yields} YBCO conductors are used in SMES. {yields} The SMES is successfully used to compensate voltage sag by both simulation and experiment. {yields} A new control strategy for the power converter in the SMES. - Abstract: This paper gives a introduction of a SMES unit using 2G HTS wires. A complete SMES system including both superconducting coils and control circuit has been designed to operate at 77 K. Three single-phase H-bridge converters have been used in the control circuit. A loop control signal is sent out by using 32 fixed point Digital Signal Processor (DSP). The complete circuit has been both modelled in simulation and built experimentally. The results validate that this SMES successfully compensates a voltage sag in a power system.

  18. Modelling of V-Hz and vector controlled ASDs in PSCAD/EMTDC for voltage sag studies

    Energy Technology Data Exchange (ETDEWEB)

    Vegunta, S.C. [TNEI Services Ltd, Manchester M1 2PW (United Kingdom); Milanovic, J.V. [School of Electrical and Electronic Engineering of The University of Manchester, PO Box 88, Manchester M60 1QD (United Kingdom); Djokic, S.Z. [School of Engineering of The University of Edinburgh, The King' s Buildings, Mayfield Road, Edinburgh EH9 3JL (United Kingdom)

    2010-01-15

    This paper deals with modelling and performance of adjustable speed drives (ASDs) subjected to voltage disturbances in electric supply. The aim of this study was to develop appropriate models of typical ASD and investigate their sensitivity to voltage disturbances under various practical modes of operation and control. Accordingly, scalar controlled open and closed loop volts-hertz (V-Hz) and vector controlled closed loop ASDs are modelled in PSCAD/EMTDC environment, and their performance in the presence of voltage disturbances is investigated under typical operating and loading conditions. The drive sensitivity to three-phase, two-phase and single-phase voltage sags and short interruptions was assessed, and the findings are discussed in the paper. Depending on the type of drive control, type of voltage sag, applied load torque and adjusted speed, various sensitivity curves were established and analyzed. (author)

  19. 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

    it can make the MG a contributor in smooth ride through the faults. In this paper, a reactive power support strategy using droop controlled converters is proposed to aid MG riding through three phase symmetrical voltage sags. In such a case, the MGs should inject reactive power to the grid to boost...... 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...

  20. Control of hybrid fuel cell/energy storage distributed generation system against voltage sag

    Energy Technology Data Exchange (ETDEWEB)

    Hajizadeh, Amin; Golkar, Masoud Aliakbar [Electrical Engineering Department, K.N. Toosi University of Technology, Seyedkhandan, Dr. Shariati Ave, P.O. Box 16315-1355, Tehran (Iran)

    2010-06-15

    Fuel cell (FC) and energy storage (ES) based hybrid distributed power generation systems appear to be very promising for satisfying high energy and high power requirements of power quality problems in distributed generation (DG) systems. In this study, design of control strategy for hybrid fuel cell/energy storage distributed power generation system during voltage sag has been presented. The proposed control strategy allows hybrid distributed generation system works properly when a voltage disturbance occurs in distribution system and hybrid system stays connected to the main grid. Hence, modeling, controller design, and simulation study of a hybrid distributed generation system are investigated. The physical model of the fuel cell stack, energy storage and the models of power conditioning units are described. Then the control design methodology for each component of the hybrid system is proposed. Simulation results are given to show the overall system performance including active power control and voltage sag ride-through capability of the hybrid distributed generation system. (author)

  1. A Simple Sag Generator Using SSRs

    DEFF Research Database (Denmark)

    Senturk, Osman Selcuk; Hava, Ahmet M.

    2010-01-01

    conditions (critical loads) and this property often may not be accommodated inside the device itself and sag compensating power conditioners have been developed for such purposes. While in practice voltage sags are not wanted, generating sags becomes necessary for the purpose of experimentally verifying...... the performances of the equipment (both the equipment under sag condition and the sag compensating power conditioner) under sag conditions. In this work, a simple and economical, yet highly performing sag generator is developed, its design discussed, and its feasibility demonstrated by experiments. The proposed...... is evaluated and finally the utilization of the sag generator in the test of a series active filter based power quality conditioner is demonstrated. The proposed approach provides an effective solution for voltage sag generation....

  2. Voltage Sag Mitigation and Load Reactive Power Compensation by UPQC

    OpenAIRE

    Ajitha, P; Jananisri, D

    2014-01-01

    This paper presents Unified Power Quality Conditioner(UPQC) that consist of series inverter and shunt inverter in back to back configuration which simultaneously compensate the power quality(PQ) problems of both voltage sag and load reactive power compensation . In this paper ,Neural network is tool which is considered for solving power quality problems. The simulation results from MATLAB/SIMULINK are discussed to validate the proposed method.

  3. Installation of the sag compensator for HANARO

    International Nuclear Information System (INIS)

    Kim, Hyung Kyoo; Jung, Hoan Sung; Lim, In Cheol; Ahn, Guk Hoon

    2008-01-01

    Electric power is essential for all industrial plants and also for nuclear facilities. HANARO is a research reactor which produces a 30MW thermal power. HANARO is designed to be tripped automatically when interruptions or some extent of sags occur. HANARO has the reactor regulation system(RRs) and reactor protection system(RPS). HANARO is designed so as to be tripped automatically by insertion of control absorber rods(CAR) and shut off rods(SOR). When voltage sag or momentary interruption occurs, the reactor has an unwanted trip by insertion of CARs and SORs even though the process systems are still in operation. HANARO was experienced in a nuisance trip as often as the unexpected voltage sag and/or momentary interruption occurs. We installed the voltage sag compensator voltage sag assessment of the AC coil contactor which is a component of the power supply unit for the SORs. The compensation time is determined to be less than 1 sec in consideration of the reactor safety. This paper is concerned with the impact of the momentary interruption on the reactor and the effect of the voltage sag compensator

  4. Analysis the Transient Process of Wind Power Resources when there are Voltage Sags in Distribution Grid

    Science.gov (United States)

    Nhu Y, Do

    2018-03-01

    Vietnam has many advantages of wind power resources. Time by time there are more and more capacity as well as number of wind power project in Vietnam. Corresponding to the increase of wind power emitted into national grid, It is necessary to research and analyze in order to ensure the safety and reliability of win power connection. In national distribution grid, voltage sag occurs regularly, it can strongly influence on the operation of wind power. The most serious consequence is the disconnection. The paper presents the analysis of distribution grid's transient process when voltage is sagged. Base on the analysis, the solutions will be recommended to improve the reliability and effective operation of wind power resources.

  5. Installation of the sag compensator for HANARO

    International Nuclear Information System (INIS)

    Kim, Hyungkyoo; Jung, Hoansung; Lim, Incheol; Ahn, Gukhoon

    2008-01-01

    Electric power is essential for all industrial plants and also for nuclear facilities. HANARO is a research reactor which produces a 30 MW thermal power. HANARO is designed to be tripped automatically when interruptions or some extent of sags occur. HANARO has the reactor regulation system(RRS) and reactor protection system(RPS). HANARO is designed so as to be tripped automatically by insertion of control absorber rods(CAR) and shut-off rods(SOR). When voltage sag or momentary interruption occurs, the reactor has an unwanted trip by insertion of CARs and SORs even though the process systems are still in operation. HANARO was experienced in a nuisance trip as often as the unexpected voltage sag and/or momentary interruption occurs. We installed the voltage sag compensator on the power supply for CARs and SORs so as to prevent an unwanted trip. We undertook voltage sag assessment of the AC coil contactor which is a component of the power supply unit for the SORs. The compensation time is determined to be less than 1 sec in consideration of the reactor safety. This paper is concerned with the impact of the momentary interruption on the reactor and the effect of the voltage sag compensator. (author)

  6. Inrush Transient Current Analysis and Suppression of Photovoltaic Grid-Connected Inverters During Voltage Sag

    DEFF Research Database (Denmark)

    Li, Zhongyu; Zhao, Rende; Xin, Zhen

    2016-01-01

    The Inrush Transient Current (ITC) in the output of the photovoltaic grid-connected inverters is usually generated when grid voltage sag occurs, which can trigger the protection of the grid-connected inverters, and even destroy the semiconductor switches. Then, the grid-connected inverters...

  7. 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.

  8. Installation of the sag compensator for HANARO

    International Nuclear Information System (INIS)

    Kim, H. K.; Jung, H. S.; Ahn, G. H.; Lim, I. C.

    2008-01-01

    Electric power is essential for all industrial plants and also for nuclear facilities. HANARO is a research reactor which produces a 30MW thermal power. HANARO is designed to be tripped automatically when interruptions or some extents of sags occur. HANARO has the reactor regulation system (RRS) and reactor protection system (RPS). HANARO is designed so as to tripped automatically by insertion of control absorber rods (CAR) and shut-off rods (SOR). When voltage or momentary interruption occurs, the reactor has an unwanted trip by insertion of CARs and SORs even though the process systems are still in operation. HANARO was experienced in a nuisance trip as often as the unexpected voltage sag and/or momentary interruption occurs. We installed the voltage sag compensator on the power supply for CARs and SORs so as to prevent an unwanted trip. We undertook voltage sag assessment of the AC coil contactor which is a component of the power supply unit for the SORs. The compensation time is determined to be less than 1 sec in consideration of the reactor safety. This paper is concerned with the impact of the momentary interruption on the reactor and the effect of the voltage sag compensator

  9. Performance Evaluation of Three Different Inverter Configurations of DVR for Mitigation of Voltage Events

    Directory of Open Access Journals (Sweden)

    Miska Prasad

    2016-12-01

    Full Text Available The voltage events namely voltage sags and voltage swells represent the most common, frequent and important power quality events in today’s power system. Dynamic voltage restorer (DVR is one of the key components used to mitigate the supply voltage quality disturbances in terms of voltage sags and swells in the distribution system. It consists of an energy storage unit, a voltage source inverter, a filter, a coupling transformer and the control system. This paper presents three different inverter configurations of dynamic voltage restorer (DVR for mitigation of voltage events such as voltage sags and swells with sudden addition or removal of the nonlinear load. These three configurations are voltage source inverter based DVR (VSI-DVR, current source inverter based DVR (CSI-DVR and impedance or Z-source inverter based DVR (ZSI-DVR. The d-q control technique is used to control the operation of the DVR. The response of ZSI-DVR for mitigation of voltage sags and swells are investigated and compared with VSI-DVR and CSI-DVR using MATLAB/SIMULINK environment.

  10. Heat-pump performance: voltage dip/sag, under-voltage and over-voltage

    Directory of Open Access Journals (Sweden)

    William J.B. Heffernan

    2014-12-01

    Full Text Available Reverse cycle air-source heat-pumps are an increasingly significant load in New Zealand and in many other countries. This has raised concern over the impact wide-spread use of heat-pumps may have on the grid. The characteristics of the loads connected to the power system are changing because of heat-pumps. Their performance during under-voltage events such as voltage dips has the potential to compound the event and possibly cause voltage collapse. In this study, results from testing six heat-pumps are presented to assess their performance at various voltages and hence their impact on voltage stability.

  11. Impact of distributed generation in the probability density of voltage sags; Impacto da geracao distribuida na densidade de probabilidade de afundamentos de tensao

    Energy Technology Data Exchange (ETDEWEB)

    Ramos, Alessandro Candido Lopes [CELG - Companhia Energetica de Goias, Goiania, GO (Brazil). Generation and Transmission. System' s Operation Center], E-mail: alessandro.clr@celg.com.br; Batista, Adalberto Jose [Universidade Federal de Goias (UFG), Goiania, GO (Brazil)], E-mail: batista@eee.ufg.br; Leborgne, Roberto Chouhy [Universidade Federal do Rio Grande do Sul (UFRS), Porto Alegre, RS (Brazil)], E-mail: rcl@ece.ufrgs.br; Emiliano, Pedro Henrique Mota, E-mail: ph@phph.com.br

    2009-07-01

    This article presents the impact of distributed generation in studies of voltage sags caused by faults in the electrical system. We simulated short-circuit-to-ground in 62 lines of 230, 138, 69 and 13.8 kV that are part of the electrical system of the city of Goiania, of Goias state . For each fault position was monitored the bus voltage of 380 V in an industrial consumer sensitive to such sags. Were inserted different levels of GD near the consumer. The simulations of a short circuit, with the monitoring bar 380 V, were performed again. A study using stochastic simulation Monte Carlo (SMC) was performed to obtain, at each level of GD, the probability curves and sags of the probability density and its voltage class. With these curves were obtained the average number of sags according to each class, that the consumer bar may be submitted annually. The simulations were performed using the Program Analysis of Simultaneous Faults - ANAFAS. In order to overcome the intrinsic limitations of the methods of simulation of this program and allow data entry via windows, a computational tool was developed in Java language. Data processing was done using the MATLAB software.

  12. An Enhanced LVRT Scheme for DFIG-based WECSs under Both Balanced and Unbalanced Grid Voltage Sags

    DEFF Research Database (Denmark)

    Mohammadi, Jafar; Afsharnia, Saeed; Ebrahimzadeh, Esmaeil

    2017-01-01

    reactive power into the grid. The passive compensator is based on a three-phase stator damping resistor (SDR) located in series with the stator windings. The proposed scheme decreases the negative effects of grid voltage sags in the DFIG system including the rotor over-currents, electromagnetic torque...

  13. A Simple Sag Generator Using SSRs

    DEFF Research Database (Denmark)

    Senturk, Osman Selcuk; Hava, Ahmet M.

    2012-01-01

    SSR (solid state relay, a semiconductor power module of triac characteristics) and variable transformer (variac) based sag generator is built for three-phase 10kVA ratings and balanced/imbalanced voltage sags are demonstrated in the laboratory. The performance under resistive and inductive loads...

  14. 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.

  15. Investigation on the Performance of UPQC-Q for Voltage Sag Mitigation and PQ Improvement at a Critical Load Point

    OpenAIRE

    Basu, Malabika; Das, S. P.; Dubey, Gopal

    2008-01-01

    The unified power quality conditioner (UPQC) is one of the major custom power solutions, which is capable of mitigating the effect of supply voltage sag at the load end or at the point of common coupling (PCC) in a distributed network. It also prevents the propagation of the load current harmonics to the utility and improves the input power factor of the load. The control of series compensator (SERC) of the UPQC is such that it injects voltage in quadrature advance to the supply current. Thus...

  16. Fifth harmonic and sag impact on PMSG wind turbines with a balancing new strategy for capacitor voltages

    International Nuclear Information System (INIS)

    Seixas, M.; Melício, R.; Mendes, V.M.F.

    2014-01-01

    Highlights: • Impact on wind turbines due to fifth harmonic and sag content. • Converter topologies considered are two-level and three-level ones. • Controllers are based on PI and fractional-order methods. • New control strategy for the selection of output voltage vectors. • Balancing voltages in the DC-link capacitors. - Abstract: This paper deals with the computing simulation of the impact on permanent magnet synchronous generator wind turbines due to fifth harmonic content and grid voltage decrease. Power converter topologies considered in the simulations are the two-level and the three-level ones. The three-level converters are limited by unbalance voltages in the DC-link capacitors. In order to lessen this limitation, a new control strategy for the selection of the output voltage vectors is proposed. Controller strategies considered in the simulation are respectively based on proportional integral and fractional-order controllers. Finally, a comparison between the results of the simulations with the two controller strategies is presented in order to show the main advantage of the proposed strategy

  17. The impacts of voltage sags in industrial electric systems; Os impactos dos afundamentos de tensao em sistemas eletricos industriais

    Energy Technology Data Exchange (ETDEWEB)

    Maia, Reinaldo Moreira [Moinhos Vera Cruz, Santa Luzia, MG (Brazil); Silva, Selenio Rocha [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil)

    2010-10-15

    The sensitiveness increasing of industrial equipment related to the perturbation of electric grid, resulting in losses to the productive chain, turns the energy quality in the subject more discussed by the electrical community. In this study case on the problems caused by voltage sags to equipment of an industrial plant from the food sector, it is presented the identification process and the adopted solutions. (author)

  18. Optimized Controller Design for a 12-Pulse Voltage Source Converter Based HVDC System

    Science.gov (United States)

    Agarwal, Ruchi; Singh, Sanjeev

    2017-12-01

    The paper proposes an optimized controller design scheme for power quality improvement in 12-pulse voltage source converter based high voltage direct current system. The proposed scheme is hybrid combination of golden section search and successive linear search method. The paper aims at reduction of current sensor and optimization of controller. The voltage and current controller parameters are selected for optimization due to its impact on power quality. The proposed algorithm for controller optimizes the objective function which is composed of current harmonic distortion, power factor, and DC voltage ripples. The detailed designs and modeling of the complete system are discussed and its simulation is carried out in MATLAB-Simulink environment. The obtained results are presented to demonstrate the effectiveness of the proposed scheme under different transient conditions such as load perturbation, non-linear load condition, voltage sag condition, and tapped load fault under one phase open condition at both points-of-common coupling.

  19. Photovoltaic-STATCOM with Low Voltage Ride through Strategy and Power Quality Enhancement in a Grid Integrated Wind-PV System

    Directory of Open Access Journals (Sweden)

    Lakshman Naik Popavath

    2018-04-01

    Full Text Available The traditional configurations of power systems are changing due to the greater penetration of renewable energy sources (solar and wind, resulting in reliability issues. At present, the most severe power quality problems in distribution systems are current harmonics, reactive power demands, and the islanding of renewables caused by severe voltage variations (voltage sag and swell. Current harmonics and voltage sag strongly affect the performance of renewable-based power systems. Various conventional methods (passive filters, capacitor bank, and UPS are not able to mitigate harmonics and voltage sag completely. Based on several studies, custom power devices can mitigate harmonics completely and slightly mitigate voltage sags with reactive power supplies. To ensure the generating units remain grid-connected during voltage sags and to improve system operation during abnormal conditions, efficient and reliable utilization of PV solar farm inverter as STATCOMs is needed. This paper elaborates the dynamic performance of a VSC-based PV-STATCOM for power quality enhancement in a grid integrated system and low voltage ride through (LVRT capability. LVRT requirements suggest that the injection of real and reactive power supports grid voltage during abnormal grid conditions. The proposed strategy was demonstrated with MATLAB simulations.

  20. 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

    strings should be reduced during voltage sags. In this paper, an algorithm is proposed for determining the reference voltage of the PV string which results in a reduction of the output power to a certain amount. The proposed algorithm calculates the reference voltage for the dc/dc converter controller......, based on the characteristics of the power-voltage curve of the PV string and therefore, no modification is required in the the controller of the dc/dc converter. Simulation results on a 50-kW PV string verified the effectiveness of the proposed algorithm in reducing the power from PV strings under......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...

  1. DESIGN OF DYNAMIC VOLTAGE RESTORER TO ENHANCE POWER QUALITY RELYING ON RENEWABLE SOURCE

    Directory of Open Access Journals (Sweden)

    Haider M. Umran

    2018-05-01

    Full Text Available Power quality improvement of low voltage grid is a great challenge that confronts the sophisticated power applications, because their performance is highly sensitive to the quality of power supply. Dynamic Voltage Restorer (DVR used widely as an efficient and skillful device to adjust electrical disturbances of the distribution grids. This paper introduces an overview of the components of the 3-phase dynamic voltage restorer and design its own control circuit. The performance of DVR was developed on the basis of the appropriate selection of Photovoltaic (PV module instead of the present conventional designs. Through this design, the need of series converter (DVR for the current from an electrical grid will end and the problems of power losses will curb. The PV-module is selected to meet the requirements of the DVR during voltage sag/swell on voltage line. The proposed system is mimicked in MATLAB software/Simulink and the findings are presented to prove the success of the design in terms of: Full congruence of the load voltage waveform with source voltage waveform, attaining 0.77% of THD analysis for the load voltage and the waveforms of PV system.

  2. Control and Testing of a Dynamic Voltage Restorer (DVR) at Medium Voltage Level

    DEFF Research Database (Denmark)

    Nielsen, John Godsk; Newman, Michael; Nielsen, Hans Ove

    2004-01-01

    power sensitive loads from voltage sags. This paper reports practical test results obtained on a medium voltage (10 kV) level using a DVR at a Distribution test facility in Kyndby, Denmark. The DVR was designed to protect a 400-kVA load from a 0.5-p.u. maximum voltage sag. The reported DVR verifies......The dynamic voltage restorer (DVR) has become popular as a cost effective solution for the protection of sensitive loads from voltage sags. Implementations of the DVR have been proposed at both a low voltage (LV) level, as well as a medium voltage (MV) level; and give an opportunity to protect high...... the use of a feed-forward and feed-back technique of the controller and it obtains both good transient and steady state responses. The effect of the DVR on the system is experimentally investigated under both faulted and non-faulted system states, for a variety of linear and non-linear loads. Variable...

  3. Benchmarking of Voltage Sag Generators

    DEFF Research Database (Denmark)

    Yang, Yongheng; Blaabjerg, Frede; Zou, Zhixiang

    2012-01-01

    The increased penetration of renewable energy systems, like photovoltaic and wind power systems, rises the concern about the power quality and stability of the utility grid. Some regulations for Low Voltage Ride-Through (LVRT) for medium voltage or high voltage applications, are coming into force...

  4. Voltage sag influence on fatigue life of the drivetrain of fixed speed wind turbines

    DEFF Research Database (Denmark)

    Veluri, Badrinath; Santos-Martin, David; Jensen, Henrik Myhre

    2011-01-01

    Occurrence of voltage sags due to electrical grid faults and other network disturbances generate transients of the generator electromagnetic torque which result in significant high stresses and noticeable vibrations for the wind turbine mechanical system and may also have a detrimental effect...... on the fatigue life of important drivetrain components. The high penetration of wind energy in the electrical grids demands new requirements for the operation of wind energy conversion systems. Although fixed speed wind turbine technology is nowadays replaced by variable speed wind turbines. In some countries...... by the stator flux oscillations which cause high transients of the generator electromagnetic torque. This paper focuses in estimating the resulting significant stresses transients due to the electromagnetic torque transients, which transmits to the wind turbine mechanical system that may have a detrimental...

  5. The Yin and Yang of SagS: Distinct Residues in the HmsP Domain of SagS Independently Regulate Biofilm Formation and Biofilm Drug Tolerance

    Science.gov (United States)

    Dingemans, Jozef; Poudyal, Bandita

    2018-01-01

    ABSTRACT The formation of inherently drug-tolerant biofilms by the opportunistic pathogen Pseudomonas aeruginosa requires the sensor-regulator hybrid SagS, with ΔsagS biofilms being unstructured and exhibiting increased antimicrobial susceptibility. Recent findings indicated SagS to function as a switch to control biofilm formation and drug tolerance independently. Moreover, findings suggested the periplasmic sensory HmsP domain of SagS is likely to be the control point in the regulation of biofilm formation and biofilm cells transitioning to a drug-tolerant state. We thus asked whether specific amino acid residues present in the HmsP domain contribute to the switch function of SagS. HmsP domain residues were therefore subjected to alanine replacement mutagenesis to identify substitutions that block the sensory function(s) of SagS, which is apparent by attached cells being unable to develop mature biofilms and/or prevent transition to an antimicrobial-resistant state. Mutant analyses revealed 32 residues that only contribute to blocking one sensory function. Moreover, amino acid residues affecting attachment and subsequent biofilm formation but not biofilm tolerance also impaired histidine kinase signaling via BfiS. In contrast, residues affecting biofilm drug tolerance but not attachment and subsequent biofilm formation negatively impacted BrlR transcription factor levels. Structure prediction suggested the two sets of residues affecting sensory functions are located in distinct areas that were previously described as being involved in ligand binding interactions. Taken together, these studies identify the molecular basis for the dual regulatory function of SagS. IMPORTANCE The membrane-bound sensory protein SagS plays a pivotal role in P. aeruginosa biofilm formation and biofilm cells gaining their heightened resistance to antimicrobial agents, with SagS being the control point at which both pathways diverge. Here, we demonstrate for the first time that the two

  6. Flexible voltage support control for three-phase distributed generation inverters under grid fault

    DEFF Research Database (Denmark)

    Camacho, Antonio; Castilla, Miguel; Miret, Jaume

    2013-01-01

    Operators describe the behavior of the energy source, regulating voltage limits and reactive power injection to remain connected and support the grid under fault. On the basis that different kinds of voltage sags require different voltage support strategies, a flexible control scheme for three phase grid...... connected inverters is proposed. In three phase balanced voltage sags, the inverter should inject reactive power in order to raise the voltage in all phases. In one or two phase faults, the main concern of the distributed generation inverter is to equalize voltages by reducing the negative symmetric...... sequence and clear the phase jump. Due to system limitations, a balance between these two extreme policies is mandatory. Thus, over-voltage and undervoltage can be avoided, and the proposed control scheme prevents disconnection while achieving the desired voltage support service. The main contribution...

  7. Voltage-current characteristics of multiterminal HVDC-VSC for offshore wind farms

    Energy Technology Data Exchange (ETDEWEB)

    Gomis-Bellmunt, Oriol [Centre d' Innovacio Tecnologica en Convertidors Estatics i Accionaments (CITCEA-UPC), Universitat Politecnica de Catalunya UPC, Av. Diagonal, 647, Pl. 2., 08028 Barcelona (Spain); IREC Catalonia Institute for Energy Research, Barcelona (Spain); Liang, Jun; Ekanayake, Janaka; Jenkins, Nicholas [School of Engineering, Cardiff University, Queen' s Buildings, The Parade, Cardiff CF24 3AA, Wales (United Kingdom)

    2011-02-15

    Voltage-current characteristics and equilibrium points for the DC voltages of multiterminal HVDC systems using voltage source converters are discussed. The wind farm rectifiers and grid connected inverters are analyzed through their operating modes, governing equations and graphical characteristics. Using the converter equations and the HVDC grid conductance matrix the equilibrium voltages and currents are found. Case studies are presented considering wind power generation, loss of a converter and voltage sags in the AC grid. (author)

  8. Extension of the Accurate Voltage-Sag Fault Location Method in Electrical Power Distribution Systems

    Directory of Open Access Journals (Sweden)

    Youssef Menchafou

    2016-03-01

    Full Text Available Accurate Fault location in an Electric Power Distribution System (EPDS is important in maintaining system reliability. Several methods have been proposed in the past. However, the performances of these methods either show to be inefficient or are a function of the fault type (Fault Classification, because they require the use of an appropriate algorithm for each fault type. In contrast to traditional approaches, an accurate impedance-based Fault Location (FL method is presented in this paper. It is based on the voltage-sag calculation between two measurement points chosen carefully from the available strategic measurement points of the line, network topology and current measurements at substation. The effectiveness and the accuracy of the proposed technique are demonstrated for different fault types using a radial power flow system. The test results are achieved from the numerical simulation using the data of a distribution line recognized in the literature.

  9. A detailed comparison of system topologies for dynamic voltage restorers

    DEFF Research Database (Denmark)

    Nielsen, J.G.; Blaabjerg, Frede

    2005-01-01

    of energy storage, with energy taken from the grid during the voltage sag, and two topologies that take energy from stored energy devices during the voltage sag. Experimental tests using a 10-kVA DVR show that the no-energy storage concept is feasible, but an improved performance can be achieved for certain...... voltage sags using stored energy topologies. The results of this comparison rank the no-storage topology with a passive shunt converter on the load side first, followed by the stored energy topology with a constant dc-link voltage....

  10. The account of sagging of wires at definition of specific potential factors of air High-Voltage Power Transmission Lines

    Directory of Open Access Journals (Sweden)

    Suslov V.M.

    2005-12-01

    Full Text Available The opportunity approached is shown, but more exact as it is usually accepted, the account of sagging of wires at definition of specific potential factors air High-Voltage Power Transmission Lines. The technique of reception of analytical expressions is resulted. For an opportunity of comparison traditional expressions for specific potential factors are resulted also. Communication of the offered and traditional analytical expressions is shown. Offered analytical expressions are not difficult for programming on a personal computer of any class and besides they allow to make an estimation of an error of traditional expressions by means of parallel definition of specific potential factors by both ways.

  11. DG Allocation Based on Reliability, Losses and Voltage Sag Considerations: an expert system approach

    Directory of Open Access Journals (Sweden)

    Sahar Abdel Moneim Moussa

    2017-03-01

    Full Text Available Expert System (ES as a branch of Artificial Intelligence (AI methodology can potentially help in solving complicated power system problems. This may be more appropriate methodology than conventional optimization techniques when contradiction between objectives appears in reaching the optimum solution. When this contradiction is the hindrance in reaching the required system operation through the application of traditional methods ES can give a hand in such case. In this paper, the  knowledge- based ES technique is proposed to reach near-optimum solution which is further directed to the optimum solution through particle swarm optimization (PSO technique. This idea is known as Hybrid-Expert-System (HES. The proposed idea is used in getting the optimum allocation of a number of distributed generation (DG units on Distribution System (DS busbars taking into consideration three issues; reliability, voltage sag, and line losses. Optimality is assessed on the economic basis by calculating money benefits (or losses resulting from DG addition considering the three aforementioned issues. The effectiveness of the proposed technique is ascertained through example.

  12. Análisis multirresolución del motor trifásico de inducción sometido a huecos de tensión Triphasic induction motor multiresolution analysis on voltage sags

    Directory of Open Access Journals (Sweden)

    M.G Macri

    2012-04-01

    Full Text Available Este documento presenta los resultados del estudio realizado de la descomposición wavelet multinivel 1D de las señales perturbadas del par electromagnético y de la velocidad del eje del motor trifásico de inducción, cuando este es sometido a diferentes tipologías de huecos de tensión según la caracterización ABC, Bollen (2000. Los huecos de tensión trifásicos (3 variables son analizados indirectamente en el efecto producido en una variable perturbada (el par electromagnético o la velocidad del eje que contiene indirectamente información del tipo de hueco de tensión trifásico producido en el estator. El estudio analiza el efecto de los siete diferentes tipos de huecos de tensión, considerando también la influencia de la duración y tensión retenida. Para cada caso se obtiene un vector cuyos elementos son los niveles de energía wavelet en los distintos niveles de descomposición de la variable analizada, mostrando que la forma en que se distribuye la energía de la señal 1D en los distintos niveles de descomposición establece una firma única para cada caso. Esta forma de descripción de los huecos de tensión producidos en el estator, basada en la descomposición multinivel de una variable perturbada, reduce la cantidad de variables a analizar y permite posteriormente la clasificación de las perturbaciones empleando técnicas de inteligencia artificial; es ventajosa pues el almacenamiento de los vectores de niveles de energía de aproximación en las bases de datos emplea menor cantidad de espacio que la necesaria para una señal temporal, y empleando una DWT reversible es posible, además, reconstruir la variable de estado temporal.This document presents the study results of the wavelet 1D multi-level decomposition of perturbed electromagnetic torque and shaft speed signals, of the three-phase induction motor, when it is subjected to different types of voltage sags, as characterization ABC, Bollen (2000. The three

  13. A dynamic voltage restorer (DVR) with selective harmonic compensation at medium voltage level

    DEFF Research Database (Denmark)

    Newman, M.J.; Holmes, D.G.; Nielsen, J.G.

    2005-01-01

    Dynamic voltage restorers (DVRs) are now becoming more established in industry to reduce the impact of voltage sags to sensitive loads. However, DVRs spend most of their time in standby mode, since voltage sags occur very infrequently, and hence their utilization is low. In principle, it would...... be advantageous if the series-connected inverter of a DVR could also be used to compensate for any steady-state load voltage harmonics, since this would increase the power quality "value-added" benefits to the grid system. However, before this can be done, consideration must be given to the control of steady......-state power through the DVR, the increased losses, and the low modulation depths at which the scheme must operate to achieve acceptable harmonic compensation performance. This paper presents a selective harmonic feedback control strategy that can be easily added to medium-voltage DVR systems to provide...

  14. Reference voltage calculation method based on zero-sequence component optimisation for a regional compensation DVR

    Science.gov (United States)

    Jian, Le; Cao, Wang; Jintao, Yang; Yinge, Wang

    2018-04-01

    This paper describes the design of a dynamic voltage restorer (DVR) that can simultaneously protect several sensitive loads from voltage sags in a region of an MV distribution network. A novel reference voltage calculation method based on zero-sequence voltage optimisation is proposed for this DVR to optimise cost-effectiveness in compensation of voltage sags with different characteristics in an ungrounded neutral system. Based on a detailed analysis of the characteristics of voltage sags caused by different types of faults and the effect of the wiring mode of the transformer on these characteristics, the optimisation target of the reference voltage calculation is presented with several constraints. The reference voltages under all types of voltage sags are calculated by optimising the zero-sequence component, which can reduce the degree of swell in the phase-to-ground voltage after compensation to the maximum extent and can improve the symmetry degree of the output voltages of the DVR, thereby effectively increasing the compensation ability. The validity and effectiveness of the proposed method are verified by simulation and experimental results.

  15. Optimized Control Strategy for a Medium-Voltage DVR-Theoretical Investigations and Experimental Results

    DEFF Research Database (Denmark)

    Meyer, Christoph; De Doncker, Rik W.; Li, Yun Wei

    2008-01-01

    Most power quality problems in distribution systems are related to voltage sags. Therefore, different solutions have been examined to compensate these sags to avoid production losses at sensitive loads. Dynamic voltage restorers (DVRs) have been proposed to provide higher power quality. Currently......, a system wide integration of DVRs is hampered because of their high cost, in particular, due to the expensive DC-link energy storage devices. The cost of these DC-link capacitors remains high because the DVR requires a minimum DC-link voltage to be able to operate and to compensate a sag. As a result, only...... a small fraction of the energy stored in the DC-link capacitor is used, which makes it impractical for DVRs to compensate relatively long voltage sags. Present control strategies are only able to minimize the distortions at the load or to allow a better utilization of the storage system by minimizing...

  16. A Case Study Of Turkish Transmission System For VoltageDips

    DEFF Research Database (Denmark)

    Inan, E.; Alboyaci, B.; Bak, Claus Leth

    2009-01-01

    Power quality problems usually appear in the form of voltage sags, transients and harmonics. From these three broad categories of power quality problems, voltage dips account the most disturbances experienced by industrial customers. Voltage dips generally refer to instantaneous short-duration vo......Power quality problems usually appear in the form of voltage sags, transients and harmonics. From these three broad categories of power quality problems, voltage dips account the most disturbances experienced by industrial customers. Voltage dips generally refer to instantaneous short...... analysis of voltage dip performance of the whole transmission system, is used to compare with results constructed fault statics from SIMPOW DIPS analysis program real data. SIMPOW DIPS software enables to calculate dip frequency for all busses and lines....

  17. Application of Boost Converter for Ride-through Capability of Adjustable Speed Drives during Sag and Swell Conditions

    OpenAIRE

    S. S. Deswal; Ratna Dahiya; D. K. Jain

    2008-01-01

    Process control and energy conservation are the two primary reasons for using an adjustable speed drive. However, voltage sags are the most important power quality problems facing many commercial and industrial customers. The development of boost converters has raised much excitement and speculation throughout the electric industry. Now utilities are looking to these devices for performance improvement and reliability in a variety of areas. Examples of these include sags,...

  18. A novel single-phase phase space-based voltage mode controller for distributed static compensator to improve voltage profile of distribution systems

    International Nuclear Information System (INIS)

    Shokri, Abdollah; Shareef, Hussain; Mohamed, Azah; Farhoodnea, Masoud; Zayandehroodi, Hadi

    2014-01-01

    Highlights: • A new phase space based voltage mode controller for D-STATCOM was proposed. • The proposed compensator was tested to mitigate voltage disturbances in distribution systems. • Voltage fluctuation, voltage sag and voltage swell are considered to evaluate the performance of the proposed compensator. - Abstract: Distribution static synchronous compensator (D-STATCOM) has been developed and attained a great interest to compensate the power quality disturbances of distribution systems. In this paper, a novel single-phase control scheme for D-STATCOM is proposed to improve voltage profile at the Point of Common Coupling (PCC). The proposed voltage mode (VM) controller is based on the phase space algorithm, which is able to rapidly detect and mitigate any voltage deviations from reference voltage including voltage sags and voltage swells. To investigate the efficiency and accuracy of the proposed compensator, a system is modeled using Matlab/Simulink. The simulation results approve the capability of the proposed VM controller to provide a regulated and disturbance-free voltage for the connected loads at the PCC

  19. Power Quality Improvement Using an Enhanced Network-Side-Shunt-Connected Dynamic Voltage Restorer

    Science.gov (United States)

    Fereidouni, Alireza; Masoum, Mohammad A. S.; Moghbel, Moayed

    2015-10-01

    Among the four basic dynamic voltage restorer (DVR) topologies, the network-side shunt-connected DVR (NSSC-DVR) has a relatively poor performance and is investigated in this paper. A new configuration is proposed and implemented for NSSC-DVR to enhance its performance in compensating (un)symmetrical deep and long voltage sags and mitigate voltage harmonics. The enhanced NSSC-DVR model includes a three-phase half-bridge semi-controlled network-side-shunt-connected rectifier and a three-phase full-bridge series-connected inverter implemented with a back-to-back configuration through a bidirectional buck-boost converter. The network-side-shunt-connected rectifier is employed to inject/draw the required energy by NSSC-DVR to restore the load voltage to its pre-fault value under sag/swell conditions. The buck-boost converter is responsible for maintaining the DC-link voltage of the series-connected inverter at its designated value in order to improve the NSSC-DVR capability in compensating deep and long voltage sags/swells. The full-bridge series-connected inverter permits to compensate unbalance voltage sags containing zero-sequence component. The harmonic compensation of the load voltage is achieved by extracting harmonics from the distorted network voltage using an artificial neural network (ANN) method called adaptive linear neuron (Adaline) strategy. Detailed simulations are performed by SIMULINK/MATLAB software for six case studies to verify the highly robustness of the proposed NSSC-DVR model under various conditions.

  20. Negative Sequence Droop Method based Hierarchical Control for Low Voltage Ride-Through in Grid-Interactive Microgrids

    DEFF Research Database (Denmark)

    Zhao, Xin; Firoozabadi, Mehdi Savaghebi; Quintero, Juan Carlos Vasquez

    2015-01-01

    . In this paper, a voltage support strategy based on negative sequence droop control, which regulate the positive/negative sequence active and reactive power flow by means of sending proper voltage reference to the inner control loop, is proposed for the grid connected MGs to ride through voltage sags under...... complex line impedance conditions. In this case, the MGs should inject a certain amount of positive and negative sequence power to the grid so that the voltage quality at load side can be maintained at a satisfied level. A two layer hierarchical control strategy is proposed in this paper. The primary...... control loop consists of voltage and current inner loops, conventional droop control and virtual impedance loop while the secondary control loop is based on positive/negative sequence droop control which can achieve power injection under voltage sags. Experimental results with asymmetrical voltage sags...

  1. SnSAG5 is an alternative surface antigen of Sarcocystis neurona strains that is mutually exclusive to SnSAG1.

    Science.gov (United States)

    Crowdus, Carolyn A; Marsh, Antoinette E; Saville, Willliam J; Lindsay, David S; Dubey, J P; Granstrom, David E; Howe, Daniel K

    2008-11-25

    Sarcocystis neurona is an obligate intracellular parasite that causes equine protozoal myeloencephalitis (EPM). Previous work has identified a gene family of paralogous surface antigens in S. neurona called SnSAGs. These surface proteins are immunogenic in their host animals, and are therefore candidate molecules for development of diagnostics and vaccines. However, SnSAG diversity exists in strains of S. neurona, including the absence of the major surface antigen gene SnSAG1. Instead, sequence for an alternative SnSAG has been revealed in two of the SnSAG1-deficient strains. Herein, we present data characterizing this new surface protein, which we have designated SnSAG5. The results indicated that the protein encoded by the SnSAG5 sequence is indeed a surface-associated molecule that has characteristics consistent with the other SAGs identified in S. neurona and related parasites. Importantly, Western blot analyses of a collection of S. neurona strains demonstrated that 6 of 13 parasite isolates express SnSAG5 as a dominant surface protein instead of SnSAG1. Conversely, SnSAG5 was not detected in SnSAG1-positive strains. One strain, which was isolated from the brain of a sea otter, did not express either SnSAG1 or SnSAG5. Genetic analysis with SnSAG5-specific primers confirmed the presence of the SnSAG5 gene in Western blot-positive strains, while also suggesting the presence of a novel SnSAG sequence in the SnSAG1-deficient, SnSAG5-deficient otter isolate. The findings provide further indication of S. neurona strain diversity, which has implications for diagnostic testing and development of vaccines against EPM as well as the population biology of Sarcocystis cycling in the opossum definitive host.

  2. Modeling and simulation of dynamic voltage restorer in power system

    International Nuclear Information System (INIS)

    Abdel Aziz, M.A.A.M.

    2012-01-01

    There are many loads subjected to several Power Quality Problems such as voltage sags/swells, unbalance, harmonics distortion, and short interruption. These loads encompass a wide range of equipment which are very sensitive to voltage disturbances. The Dynamic Voltage Restorer (DVR) has recently been introduced to protect sensitive loads from voltage sags and other voltage disturbances in addition to this, it mitigates current harmonics distortion. It is a series connected power electronic based device. It is considered as one of the most efficient and effective solutions. Its appeal includes smaller size and fast dynamic response to disturbances. This work describes a proposal of the DVR to improve power quality distribution (medium voltage) system. The control of the compensation voltage and harmonics cancellation in the DVR is based on Adaptive Noise Canceling (ANC) technique. Simulation results carried out by PSCAD/EMTDC to investigate the performance of the proposed method.

  3. Advanced DVR with Zero-Sequence Voltage Component and Voltage Harmonic Elimination for Three-Phase Three-Wire Distribution Systems

    Directory of Open Access Journals (Sweden)

    Margo P

    2009-11-01

    Full Text Available Dynamic Voltage Restorer (DVR is a power electronics device to protect sensitive load when voltage sag occurs. Commonly, sensitive loads are electronic-based devices which generate harmonics. The magnitude and phase of compensated voltage in DVR depend on grounding system and type of fault. If the system is floating, the zero sequence components do not appear on the load side. Meanwhile, in a neutral grounded system, voltage sag is extremely affected by zero sequence components. A blocking transformer is commonly installed in series with DVR to reduce the effect of zero sequence components. This paper proposes a new DVR control scheme that is capable of eliminating the blocking transformer and reducing harmonic distortion. The system uses fuzzy polar controller to replace the conventional PI or FL controller that is commonly used. By taking into account the zero sequence components in the controller design, the effects of zero sequence components can be compensated. Simulated results show the effectiveness of the proposed DVR controller

  4. Antimicrobial Tolerance of Pseudomonas aeruginosa Biofilms Is Activated during an Early Developmental Stage and Requires the Two-Component Hybrid SagS

    Science.gov (United States)

    Gupta, Kajal; Marques, Cláudia N. H.; Petrova, Olga E.

    2013-01-01

    A hallmark characteristic of biofilms is their extraordinary tolerance to antimicrobial agents. While multiple factors are thought to contribute to the high level of antimicrobial tolerance of biofilms, little is known about the timing of induction of biofilm tolerance. Here, we asked when over the course of their development do biofilms gain their tolerance to antimicrobial agents? We demonstrate that in Pseudomonas aeruginosa, biofilm tolerance is linked to biofilm development, with transition to the irreversible attachment stage regulated by the two-component hybrid SagS, marking the timing when biofilms switch to the high-level tolerance phenotype. Inactivation of sagS rendered biofilms but not planktonic cells more susceptible to tobramycin, norfloxacin, and hydrogen peroxide. Moreover, inactivation of sagS also eliminated the recalcitrance of biofilms to killing by bactericidal antimicrobial agents, a phenotype comparable to that observed upon inactivation of brlR, which encodes a MerR-like transcriptional regulator required for biofilm tolerance. Multicopy expression of brlR in a ΔsagS mutant restored biofilm resistance and recalcitrance to killing by bactericidal antibiotics to wild-type levels. In contrast, expression of sagS did not restore the susceptibility phenotype of ΔbrlR mutant biofilms to wild-type levels, indicating that BrlR functions downstream of SagS. Inactivation of sagS correlated with reduced BrlR levels in biofilms, with the produced BrlR being impaired in binding to the previously described BrlR-activated promoters of the two multidrug efflux pump operons mexAB-oprM and mexEF-oprN. Our findings demonstrate that biofilm tolerance is linked to early biofilm development and SagS, with SagS contributing indirectly to BrlR activation. PMID:23995639

  5. Improvement of Voltage Stability in Electrical Network by Using a STATCOM

    Directory of Open Access Journals (Sweden)

    Kamel MERINI

    2014-02-01

    Full Text Available This paper aims to clarify power flow without and with static synchronous compensator (STATCOM and searching the best location of STATCOM to improve voltage in the Algerian network. In daily operation where there are all kinds of disturbances such as voltage fluctuations, voltage sags, swells, voltage unbalances and harmonics. STATCOM is modeled as a controllable voltage source. To validate the effectiveness of the Newton-Raphson method algorithm was implemented to solve power flow equations in presence of STATCOM. Case studies are carried out on 59-bus Algerian network test to demonstrate the performance of proposed models. Simulation results show the effectiveness and capability of STATCOM in improving voltage regulation in transmission systems; moreover the power solution using the Newton-Raphson algorithm developed. The STATCOM and the detailed simulation are performed using Matlab program.

  6. Comparison between Different Control Strategies of a Z-Source Inverter Based Dynamic Voltage Restorer

    Directory of Open Access Journals (Sweden)

    Abolfazl Kazemdehdashti

    2013-01-01

    Full Text Available In this paper, dynamic voltage restorer (DVR compensation methods are compared to each other for the load side connected shunt converter topology of z-source inverter based DVR to choose the best method. Four different topologies are recognized for DVR that two of them have energy storage devices, and two topologies have no energy storage that take ener\\-gy from the grid during the period of compensation. Here the load side connected shunt converter topology that takes necessary energy from the grid is used. Pre-sag compensation, in-phase compensation, energy-optimized methods are the three DVR compensation methods that studied and compared. A deep analysis through different diagrams would show the advantages or disadvantages of each compensation method. Equations for all methods are derived and the characteristics of algorithms are compared with each other. The simulation results done by SIMULINK/ MATLAB shows compensating by this topology based on the compensation methods.

  7. A dulal-functional medium voltage level DVR to limit downstream fault currents

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Li, Yun Wei; Vilathgamuwa, D. Mahinda

    2007-01-01

    on the other parallel feeders connected to PCC. Furthermore, if not controlled properly, the DVR might also contribute to this PCC voltage sag in the process of compensating the missing voltage, thus further worsening the fault situation. To limit the flow of large line currents, and therefore restore the PCC...... situations. Controlling the DVR as a virtual inductor would also ensure zero real power absorption during the DVR compensation and thus minimize the stress in the dc link. Finally, the proposed fault current limiting algorithm has been tested in Matlab/Simulink simulation and experimentally on a medium......The dynamic voltage restorer (DVR) is a modern custom power device used in power distribution networks to protect consumers from sudden sags (and swells) in grid voltage. Implemented at medium voltage level, the DVR can be used to protect a group of medium voltage or low voltage consumers. However...

  8. Traffic Flow at Sags : Theory, Modeling and Control

    NARCIS (Netherlands)

    Goni-Ros, B.

    2016-01-01

    Sag vertical curves (sags) are roadway sections along which the gradient increases gradually in the direction of traffic. Empirical observations show that, on freeways, traffic congestion often occurs at sags; actually, in some countries (e.g., Japan), sags are one of the most common types of

  9. A Hybrid, Current-Source/Voltage-Source Power Inverter Circuit

    DEFF Research Database (Denmark)

    Trzynadlowski, Andrzej M.; Patriciu, Niculina; Blaabjerg, Frede

    2001-01-01

    A combination of a large current-source inverter and a small voltage-source inverter circuits is analyzed. The resultant hybrid inverter inherits certain operating advantages from both the constituent converters. In comparison with the popular voltage-source inverter, these advantages include...... reduced switching losses, improved quality of output current waveforms, and faster dynamic response to current control commands. Description of operating principles and characteristics of the hybrid inverter is illustrated with results of experimental investigation of a laboratory model....

  10. Quantifying the gantry sag on linear accelerators and introducing an MLC-based compensation strategy

    Energy Technology Data Exchange (ETDEWEB)

    Du Weiliang; Gao Song; Wang Xiaochun; Kudchadker, Rajat J. [Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston, Texas 77030 (United States)

    2012-04-15

    Purpose: Gantry sag is one of the well-known sources of mechanical imperfections that compromise the spatial accuracy of radiation dose delivery. The objectives of this study were to quantify the gantry sag on multiple linear accelerators (linacs), to investigate a multileaf collimator (MLC)-based strategy to compensate for gantry sag, and to verify the gantry sag and its compensation with film measurements. Methods: The authors used the Winston-Lutz method to measure gantry sag on three Varian linacs. A ball bearing phantom was imaged with megavolt radiation fields at 10 deg. gantry angle intervals. The images recorded with an electronic portal imaging device were analyzed to derive the radiation isocenter and the gantry sag, that is, the superior-inferior wobble of the radiation field center, as a function of the gantry angle. The authors then attempted to compensate for the gantry sag by applying a gantry angle-specific correction to the MLC leaf positions. The gantry sag and its compensation were independently verified using film measurements. Results: Gantry sag was reproducible over a six-month measurement period. The maximum gantry sag was found to vary from 0.7 to 1.0 mm, depending on the linac and the collimator angle. The radiation field center moved inferiorly (i.e., away from the gantry) when the gantry was rotated from 0 deg. to 180 deg. After the MLC leaf position compensation was applied at 90 deg. collimator angle, the maximum gantry sag was reduced to <0.2 mm. The film measurements at gantry angles of 0 deg. and 180 deg. verified the inferior shift of the radiation fields and the effectiveness of MLC compensation. Conclusions: The results indicate that gantry sag on a linac can be quantitatively measured using a simple phantom and an electronic portal imaging device. Reduction of gantry sag is feasible by applying a gantry angle-specific correction to MLC leaf positions at 90 deg. collimator angle.

  11. Mitigation of voltage sag using DVR under feedback and ...

    African Journals Online (AJOL)

    The paper deals with Dynamic Voltage Restorer (DVR) that aims at the integration of series active filter with minimum VA handling. The DVR not only regulates the voltage at load end but also acts as series active filter. The scheme of DVR is modeled and simulated with MATLAB/Simulink under feedback and feedforward ...

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

    DEFF Research Database (Denmark)

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

    2013-01-01

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

  13. Sarcocystis neurona merozoites express a family of immunogenic surface antigens that are orthologues of the Toxoplasma gondii surface antigens (SAGs) and SAG-related sequences.

    Science.gov (United States)

    Howe, Daniel K; Gaji, Rajshekhar Y; Mroz-Barrett, Meaghan; Gubbels, Marc-Jan; Striepen, Boris; Stamper, Shelby

    2005-02-01

    Sarcocystis neurona is a member of the Apicomplexa that causes myelitis and encephalitis in horses but normally cycles between the opossum and small mammals. Analysis of an S. neurona expressed sequence tag (EST) database revealed four paralogous proteins that exhibit clear homology to the family of surface antigens (SAGs) and SAG-related sequences of Toxoplasma gondii. The primary peptide sequences of the S. neurona proteins are consistent with the two-domain structure that has been described for the T. gondii SAGs, and each was predicted to have an amino-terminal signal peptide and a carboxyl-terminal glycolipid anchor addition site, suggesting surface localization. All four proteins were confirmed to be membrane associated and displayed on the surface of S. neurona merozoites. Due to their surface localization and homology to T. gondii surface antigens, these S. neurona proteins were designated SnSAG1, SnSAG2, SnSAG3, and SnSAG4. Consistent with their homology, the SnSAGs elicited a robust immune response in infected and immunized animals, and their conserved structure further suggests that the SnSAGs similarly serve as adhesins for attachment to host cells. Whether the S. neurona SAG family is as extensive as the T. gondii SAG family remains unresolved, but it is probable that additional SnSAGs will be revealed as more S. neurona ESTs are generated. The existence of an SnSAG family in S. neurona indicates that expression of multiple related surface antigens is not unique to the ubiquitous organism T. gondii. Instead, the SAG gene family is a common trait that presumably has an essential, conserved function(s).

  14. Sarcocystis neurona Merozoites Express a Family of Immunogenic Surface Antigens That Are Orthologues of the Toxoplasma gondii Surface Antigens (SAGs) and SAG-Related Sequences†

    Science.gov (United States)

    Howe, Daniel K.; Gaji, Rajshekhar Y.; Mroz-Barrett, Meaghan; Gubbels, Marc-Jan; Striepen, Boris; Stamper, Shelby

    2005-01-01

    Sarcocystis neurona is a member of the Apicomplexa that causes myelitis and encephalitis in horses but normally cycles between the opossum and small mammals. Analysis of an S. neurona expressed sequence tag (EST) database revealed four paralogous proteins that exhibit clear homology to the family of surface antigens (SAGs) and SAG-related sequences of Toxoplasma gondii. The primary peptide sequences of the S. neurona proteins are consistent with the two-domain structure that has been described for the T. gondii SAGs, and each was predicted to have an amino-terminal signal peptide and a carboxyl-terminal glycolipid anchor addition site, suggesting surface localization. All four proteins were confirmed to be membrane associated and displayed on the surface of S. neurona merozoites. Due to their surface localization and homology to T. gondii surface antigens, these S. neurona proteins were designated SnSAG1, SnSAG2, SnSAG3, and SnSAG4. Consistent with their homology, the SnSAGs elicited a robust immune response in infected and immunized animals, and their conserved structure further suggests that the SnSAGs similarly serve as adhesins for attachment to host cells. Whether the S. neurona SAG family is as extensive as the T. gondii SAG family remains unresolved, but it is probable that additional SnSAGs will be revealed as more S. neurona ESTs are generated. The existence of an SnSAG family in S. neurona indicates that expression of multiple related surface antigens is not unique to the ubiquitous organism T. gondii. Instead, the SAG gene family is a common trait that presumably has an essential, conserved function(s). PMID:15664946

  15. Spectrum analysis of a voltage source converter due to semiconductor voltage drops

    DEFF Research Database (Denmark)

    Rasmussen, Tonny Wederberg; Eltouki, Mustafa

    2017-01-01

    It is known that power electronic voltage source converters are non-ideal. This paper presents a state-of-the-art review on the effect of semiconductor voltage drop on the output voltage spectrum, using single-phase H-bridge two-level converter topology with natural sampled pulse width modulation....... The paper describes the analysis of output voltage spectrum, when the semiconductor voltage drop is added. The results of the analysis of the spectral contribution including and excluding semiconductor voltage drop reveal a good agreement between the theoretical results, simulations and laboratory...

  16. Model Predictive Control for an Industrial SAG Mill

    DEFF Research Database (Denmark)

    Ohan, Valeriu; Steinke, Florian; Metzger, Michael

    2012-01-01

    identication. When applied to MIMO systems we call this controller a MIMO-ARX based MPC. We use an industrial Semi-Autogenous Grinding (SAG) mill to illustrate the performance of this controller. SAG mills are the primary units in a grinding chain and also the most power consuming units. Therefore, improved...... control of SAG mills has the potential to signicantly improve eciency and reduce the specic energy consumption for mineral processes. Grinding circuits involving SAG mills are multivariate processes. Commissioning of a control system based on a classical single-loop controllers with logic is time...

  17. Power Quality Problems Mitigation using Dynamic Voltage Restorer in Egypt Thermal Research Reactor (ETRR-2)

    International Nuclear Information System (INIS)

    Kandil, T.; Ayad, N.M.; Abdel Haleam, A.; Mahmoud, M.

    2013-01-01

    Egypt thermal research reactor (ETRR-2) was subjected to several Power Quality Problems such as voltage sags/swells, harmonics distortion, and short interruption. ETRR-2 encompasses a wide range of loads which are very sensitive to voltage variations and this leads to several unplanned shutdowns of the reactor due to trigger of the Reactor Protection System (RPS). The Dynamic Voltage Restorer (DVR) has recently been introduced to protect sensitive loads from voltage sags and other voltage disturbances. It is considered as one of the most efficient and effective solution. Its appeal includes smaller size and fast dynamic response to the disturbance. This paper describes a proposal of a DVR to improve power quality in ETRR-2 electrical distribution systems . The control of the compensation voltage is based on d-q-o algorithm. Simulation is carried out by Matlab/Simulink to verify the performance of the proposed method

  18. A Robust Control Scheme for Medium-Voltage-Level DVR Implementation

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Loh, Poh Chiang; Li, Yun Wei

    2007-01-01

    of Hinfin controller weighting function selection, inner current loop tuning, and system disturbance rejection capability is presented. Finally, the designed control scheme is extensively tested on a laboratory 10-kV MV-level DVR system with varying voltage sag (balanced and unbalanced) and loading (linear....../nonlinear load and induction motor load) conditions. It is shown that the proposed control scheme is effective in both balanced and unbalanced sag compensation and load disturbance rejection, as its robustness is explicitly specified....

  19. Diode-Assisted Buck-Boost Voltage-Source Inverters

    DEFF Research Database (Denmark)

    Gao, Feng; Loh, Poh Chiang; Teodorescu, Remus

    2009-01-01

    , a number of diode-assisted inverter variants can be designed with each having its own operational principle and voltage gain expression. For controlling them, a generic modulation scheme that can be used for controlling all diode-assisted variants with minimized harmonic distortion and component stress......This paper proposes a number of diode-assisted buck-boost voltage-source inverters with a unique X-shaped diode-capacitor network inserted between the inverter circuitry and dc source for producing a voltage gain that is comparatively higher than those of other buck-boost conversion techniques....... Using the diode-assisted network, the proposed inverters can naturally configure themselves to perform capacitive charging in parallel and discharging in series to give a higher voltage multiplication factor without compromising waveform quality. In addition, by adopting different front-end circuitries...

  20. The Early Cambrian Mianyang-Changning Intracratonic Sag and Its Control on Petroleum Accumulation in the Sichuan Basin, China

    Directory of Open Access Journals (Sweden)

    Shugen Liu

    2017-01-01

    Full Text Available The older and deeper hydrocarbon accumulations receive increasing attention across the world, providing more technical and commercial challenges to hydrocarbon exploration. We present a study of an asymmetrical, N-S striking intracratonic sag which developed across the Sichuan basin, south China, from Late Ediacaran to Early Cambrian times. The Mianyang-Changning intracratonic sag is ~50 km wide, with its steepest part in the basin center. In particular the eastern margin shows its greatest steepness. Five episodes in the evolutions of the sag can be recognized. It begins in the Late Ediacaran with an uplift and erosion correlated to Tongwan movement. Initial extension occurred during the Early Cambrian Maidiping period, when more strata of the Maidiping Formation were deposited across the sag. Subsequently, maximum extension occurred during the Early Cambrian Qiongzhusi period that resulted in 450–1700 m thick Maidiping-Canglangpu Formations being deposited in the sag. Then, the sag disappeared at the Longwangmiao period, as it was infilled by the sediments. The intracratonic sag has significant influence on the development of high-quality reservoirs in the Dengying and Longwangmiao Formations and source-rock of the Niutitang Formation. It thus indicates that a high probability for oil/gas accumulation exists along the intracratonic sag, across the central Sichuan basin.

  1. A flexible low-voltage ride-through operation for the distributed generation converters

    DEFF Research Database (Denmark)

    Chen, Hsin-Chih; Lee, Chia-Tse; Cheng, Po-Tai

    2013-01-01

    With more and more distributed energy resources (DERs) are installed in the utility grid, the utility requires the DER generation system to remain grid-connected and injects reactive and active power to support grid voltage during voltage sags. In this paper, a positive- and negative-sequence cur...

  2. Generic inertia emulation controller for multi-terminal voltage-source-converter high voltage direct current systems

    DEFF Research Database (Denmark)

    Zhu, Jiebei; Guerrero, Josep M.; Hung, William

    2014-01-01

    A generic Inertia Emulation Controller (INEC) scheme for Multi-Terminal Voltage-Source-Converter based HVDC (VSC-MTDC) systems is proposed and presented in this paper. The proposed INEC can be incorporated in any Grid-side Voltage-Source-Converter (GVSC) station, allowing the MTDC terminal...

  3. Optimal condition of memristance enhancement circuit using external voltage source

    Directory of Open Access Journals (Sweden)

    Hiroya Tanaka

    2014-05-01

    Full Text Available Memristor provides nonlinear response in the current-voltage characteristic and the memristance is modulated using an external voltage source. We point out by solving nonlinear equations that an optimal condition of the external voltage source exists for maximizing the memristance in such modulation scheme. We introduce a linear function to describe the nonlinear time response and derive an important design guideline; a constant ratio of the frequency to the amplitude of the external voltage source maximizes the memristance. The analysis completely accounts for the memristance behavior.

  4. Design and control of single-phase dynamic voltage restorer

    Indian Academy of Sciences (India)

    Amit Meena

    ... voltage sag and swell. Modelling of the DVR and its controller design is included in ..... simulation study of DVR is accomplished in MATLAB/. Simulink. Parameters of ..... During this process, the PWM signals generated by the DSP are not as ...

  5. Low Voltage Ride-Through Capability Solutions for Permanent Magnet Synchronous Wind Generators

    Directory of Open Access Journals (Sweden)

    Victor F. Mendes

    2016-01-01

    Full Text Available Due to the increasing number of wind power plants, several countries have modified their grid codes to include specific requirements for the connection of this technology to the power system. One of the requirements is the ride-through fault capability (RTFC, i.e., the system capability to sustain operation during voltage sags. In this sense, the present paper intends to investigate the behavior of a full-converter wind generator with a permanent magnet synchronous machine during symmetrical and asymmetrical voltage sags. Two solutions to improve the low voltage ride-through capability (LVRT of this technology are analyzed: discharging resistors (brake chopper and resonant controllers (RCs. The design and limitations of these solutions and the others proposed in the literature are discussed. Experimental results in a 34 kW test bench, which represents a scaled prototype of a real 2 MW wind conversion system, are presented.

  6. Double input converters for different voltage sources with isolated charger

    Directory of Open Access Journals (Sweden)

    Chalash Sattayarak

    2014-09-01

    Full Text Available This paper presents the double input converters for different voltage input sources with isolated charger coils. This research aims to increase the performance of the battery charger circuit. In the circuit, there are the different voltage levels of input source. The operating modes of the switch in the circuit use the microcontroller to control the battery charge and to control discharge mode automatically when the input voltage sources are lost from the system. The experimental result of this research shows better performance for charging at any time period of the switch, while the voltage input sources work together. Therefore, this research can use and develop to battery charger for present or future.

  7. Performance evaluation of wideband bio-impedance spectroscopy using constant voltage source and constant current source

    International Nuclear Information System (INIS)

    Mohamadou, Youssoufa; Oh, Tong In; Wi, Hun; Sohal, Harsh; Farooq, Adnan; Woo, Eung Je; McEwan, Alistair Lee

    2012-01-01

    Current sources are widely used in bio-impedance spectroscopy (BIS) measurement systems to maximize current injection for increased signal to noise while keeping within medical safety specifications. High-performance current sources based on the Howland current pump with optimized impedance converters are able to minimize stray capacitance of the cables and setup. This approach is limited at high frequencies primarily due to the deteriorated output impedance of the constant current source when situated in a real measurement system. For this reason, voltage sources have been suggested, but they require a current sensing resistor, and the SNR reduces at low impedance loads due to the lower current required to maintain constant voltage. In this paper, we compare the performance of a current source-based BIS and a voltage source-based BIS, which use common components. The current source BIS is based on a Howland current pump and generalized impedance converters to maintain a high output impedance of more than 1 MΩ at 2 MHz. The voltage source BIS is based on voltage division between an internal current sensing resistor (R s ) and an external sample. To maintain high SNR, R s is varied so that the source voltage is divided more or less equally. In order to calibrate the systems, we measured the transfer function of the BIS systems with several known resistor and capacitor loads. From this we may estimate the resistance and capacitance of biological tissues using the least-squares method to minimize error between the measured transimpedance excluding the system transfer function and that from an impedance model. When tested on realistic loads including discrete resistors and capacitors, and saline and agar phantoms, the voltage source-based BIS system had a wider bandwidth of 10 Hz to 2.2 MHz with less than 1% deviation from the expected spectra compared to more than 10% with the current source. The voltage source also showed an SNR of at least 60 dB up to 2.2 MHz

  8. Solid-state high voltage modulator and its application to rf source high voltage power supplies

    International Nuclear Information System (INIS)

    Tooker, J.F.; Huynh, P.; Street, R.W.

    2009-01-01

    A solid-state high voltage modulator is described in which series-connected insulated-gate bipolar transistors (IGBTs) are switched at a fixed frequency by a pulse width modulation (PWM) regulator, that adjusts the pulse width to control the voltage out of an inductor-capacitor filter network. General Atomics proposed the HV power supply (HVPS) topology of multiple IGBT modulators connected to a common HVdc source for the large number of 1 MW klystrons in the linear accelerator of the Accelerator Production of Tritium project. The switching of 24 IGBTs to obtain 20 kVdc at 20 A for short pulses was successfully demonstrated. This effort was incorporated into the design of a -70 kV, 80 A, IGBT modulator, and in a short-pulse test 12 IGBTs regulated -5 kV at 50 A under PWM control. These two tests confirm the practicality of solid-state IGBT modulators to regulate high voltage at reasonable currents. Tokamaks such as ITER require large rf heating and current drive systems with multiple rf sources. A HVPS topology is presented that readily adapts to the three rf heating systems on ITER. To take advantage of the known economy of scale for power conversion equipment, a single HVdc source feeds multiple rf sources. The large power conversion equipment, which is located outside, converts the incoming utility line voltage directly to the HVdc needed for the class of rf sources connected to it, to further reduce cost. The HVdc feeds a set of IGBT modulators, one for each rf source, to independently control the voltage applied to each source, maximizing operational flexibility. Only the modulators are indoors, close to the rf sources, minimizing the use of costly near-tokamak floor space.

  9. Voltage-regulating constant-current sources in a linear induction accelerator

    International Nuclear Information System (INIS)

    Zhao Juan; Cao Kefeng; Deng Jianjun; Zhu Lijun; Yang Jia; Ye Chao; Huang Bin; Cao Ningxiang; Dong Jinxuan; Zhang Jichang; Yu Zhiguo; Chen Min

    2002-01-01

    Constant-current Sources are one of key units in a linear induction accelerator. The requirements for the sources are to supply stable direct current of high power for the induction coil, be easy to computer-control and highly stable and reliable. Applying the technique of linear current source regulating in series, the primary voltage of the power transformer is regulated through an MJYS-JL-350A type three-phase alterative voltage-regulating module. The output current variation is 300-500 A when the load variation is 0.06-0.1 Ω and the voltage drop of the regulator tube is controlled within 8 V±2V when the variation of mains voltage is in ±10%. Both the current ripple and stability meet the technical requirements. The constant-current sources are controlled through an industrial controller. For each of the constant-current sources has a smallest system comprised of 8051 which is communication-controlled through a RS-485 interface, the sources can be controlled remotely

  10. High voltage holding in the negative ion sources with cesium deposition

    Energy Technology Data Exchange (ETDEWEB)

    Belchenko, Yu.; Abdrashitov, G.; Ivanov, A.; Sanin, A.; Sotnikov, O., E-mail: O.Z.Sotnikov@inp.nsk.su [Budker Institute of Nuclear Physics, Siberian Branch of Russian Academy of Sciences, Novosibirsk (Russian Federation)

    2016-02-15

    High voltage holding of the large surface-plasma negative ion source with cesium deposition was studied. It was found that heating of ion-optical system electrodes to temperature >100 °C facilitates the source conditioning by high voltage pulses in vacuum and by beam shots. The procedure of electrode conditioning and the data on high-voltage holding in the negative ion source with small cesium seed are described. The mechanism of high voltage holding improvement by depletion of cesium coverage is discussed.

  11. 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

  12. An Inexpensive Source of High Voltage

    Science.gov (United States)

    Saraiva, Carlos

    2012-01-01

    As a physics teacher I like recycling old apparatus and using them for demonstrations in my classes. In physics laboratories in schools, sources of high voltage include induction coils or electronic systems that can be bought from companies that sell lab equipment. But these sources can be very expensive. In this article, I will explain how you…

  13. Transmission line sag calculations using interval mathematics

    Energy Technology Data Exchange (ETDEWEB)

    Shaalan, H. [Institute of Electrical and Electronics Engineers, Washington, DC (United States)]|[US Merchant Marine Academy, Kings Point, NY (United States)

    2007-07-01

    Electric utilities are facing the need for additional generating capacity, new transmission systems and more efficient use of existing resources. As such, there are several uncertainties associated with utility decisions. These uncertainties include future load growth, construction times and costs, and performance of new resources. Regulatory and economic environments also present uncertainties. Uncertainty can be modeled based on a probabilistic approach where probability distributions for all of the uncertainties are assumed. Another approach to modeling uncertainty is referred to as unknown but bounded. In this approach, the upper and lower bounds on the uncertainties are assumed without probability distributions. Interval mathematics is a tool for the practical use and extension of the unknown but bounded concept. In this study, the calculation of transmission line sag was used as an example to demonstrate the use of interval mathematics. The objective was to determine the change in cable length, based on a fixed span and an interval of cable sag values for a range of temperatures. The resulting change in cable length was an interval corresponding to the interval of cable sag values. It was shown that there is a small change in conductor length due to variation in sag based on the temperature ranges used in this study. 8 refs.

  14. Compensation for gravitational sag of bent mirror

    Energy Technology Data Exchange (ETDEWEB)

    Mao, Chengwen; Jiang, Hui; He, Yan; Liang, Dongxu; Lan, Xuying; Yan, Shuai [Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, CAS, Shanghai 201800 (China); Shu, De-ming [Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439 (United States); Li, Aiguo, E-mail: aiguo.li@sinap.ac.cn [Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, CAS, Shanghai 201800 (China)

    2017-05-01

    The gravitational sag of aspheric bent mirrors with face-up or face-down geometry produces a nonnegligible optical error. As an effective compensation, width optimization is used to match the combined effects of the gravitational and bending moments. This method is described by analytical expressions and two calculation algorithms. The results of theoretical simulations and finite element analysis have proved that this method can reduce the slope error resulting from gravitational sag to the level of nano radians.

  15. Compensation for gravitational sag of bent mirror

    International Nuclear Information System (INIS)

    Mao, Chengwen; Jiang, Hui; He, Yan; Liang, Dongxu; Lan, Xuying; Yan, Shuai; Shu, De-ming; Li, Aiguo

    2017-01-01

    The gravitational sag of aspheric bent mirrors with face-up or face-down geometry produces a nonnegligible optical error. As an effective compensation, width optimization is used to match the combined effects of the gravitational and bending moments. This method is described by analytical expressions and two calculation algorithms. The results of theoretical simulations and finite element analysis have proved that this method can reduce the slope error resulting from gravitational sag to the level of nano radians.

  16. Computation and measurement of calandria tube sag in PHWR

    International Nuclear Information System (INIS)

    Kim, Tae Ryong; Sohn, Seok Man

    2003-01-01

    Calandria tubes and liquid injection shutdown system (LISS) tubes in a pressurized heavy water reactor (PHWR) is known to sag due to irradiation creep and growth during plant operation. When the sag of calandria tube becomes bigger, the calandria tube possibly comes in contact with LISS tube crossing beneath and calandria tube. The contact subsequently may cause the damage on the calandria tube resulting in unpredicted outage of the plant. It is therefore necessary to check the gap between the two tubes in order to periodically confirm no contact by using a proper measure during the plant life. An ultrasonic gap measuring probe assembly which can be inserted into two viewing ports of the calandria was developed in Korea and utilized to measure the sags of both tubes in the PHWR. It was found that the centerlines of calandria tubes and liquid injection shutdown system tubes can be precisely detected by ultrasonic wave. The gaps between two tubes were easily obtained from the relative distance of the measured centerline elevations of the tubes. Based on the irradiation creep equation and the measurement data, a computer program to calculate the sags was also developed. With the computer program, the sag at the end of plant life was predicted. (author)

  17. Electrical engineering unit for the reactive power control of the load bus at the voltage instability

    Science.gov (United States)

    Kotenev, A. V.; Kotenev, V. I.; Kochetkov, V. V.; Elkin, D. A.

    2018-01-01

    For the purpose of reactive power control error reduction and decrease of the voltage sags in the electric power system caused by the asynchronous motors started the mathematical model of the load bus was developed. The model was built up of the sub-models of the following elements: a transformer, a transmission line, a synchronous and an asynchronous loads and a capacitor bank load, and represents the automatic reactive power control system taking into account electromagnetic processes of the asynchronous motors started and reactive power changing of the electric power system elements caused by the voltage fluctuation. The active power/time and reactive power/time characteristics based on the recommended procedure of the equivalent electric circuit parameters calculation were obtained. The derived automatic reactive power control system was shown to eliminate the voltage sags in the electric power system caused by the asynchronous motors started.

  18. Modeling generalized interline power-flow controller (GIPFC using 48-pulse voltage source converters

    Directory of Open Access Journals (Sweden)

    Amir Ghorbani

    2018-05-01

    Full Text Available Generalized interline power-flow controller (GIPFC is one of the voltage-source controller (VSC-based flexible AC transmission system (FACTS controllers that can independently regulate the power-flow over each transmission line of a multiline system. This paper presents the modeling and performance analysis of GIPFC based on 48-pulsed voltage-source converters. This paper deals with a cascaded multilevel converter model, which is a 48-pulse (three levels voltage source converter. The voltage source converter described in this paper is a harmonic neutralized, 48-pulse GTO converter. The GIPFC controller is based on d-q orthogonal coordinates. The algorithm is verified using simulations in MATLAB/Simulink environment. Comparisons between unified power flow controller (UPFC and GIPFC are also included. Keywords: Generalized interline power-flow controller (GIPFC, Voltage source converter (VCS, 48-pulse GTO converter

  19. Source of high-voltage power supply for ozone generators at glow discharge

    International Nuclear Information System (INIS)

    Bruev, A.A.; Golota, V.I.; Zavada, L.M.; Taran, G.V.

    2000-01-01

    High-voltage power supply source on quasi-resonance inverter base which works at direct current regime is described. This source forms 20 kV voltage with 0 - 10 mA current regulation. It protects the source from current break-downs and feeds ozone generators at glow discharge

  20. 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

  1. Detection and correction for EPID and gantry sag during arc delivery using cine EPID imaging.

    Science.gov (United States)

    Rowshanfarzad, Pejman; Sabet, Mahsheed; O'Connor, Daryl J; McCowan, Peter M; McCurdy, Boyd M C; Greer, Peter B

    2012-02-01

    Electronic portal imaging devices (EPIDs) have been studied and used for pretreatment and in-vivo dosimetry applications for many years. The application of EPIDs for dosimetry in arc treatments requires accurate characterization of the mechanical sag of the EPID and gantry during rotation. Several studies have investigated the effects of gravity on the sag of these systems but each have limitations. In this study, an easy experiment setup and accurate algorithm have been introduced to characterize and correct for the effect of EPID and gantry sag during arc delivery. Three metallic ball bearings were used as markers in the beam: two of them fixed to the gantry head and the third positioned at the isocenter. EPID images were acquired during a 360° gantry rotation in cine imaging mode. The markers were tracked in EPID images and a robust in-house developed MATLAB code was used to analyse the images and find the EPID sag in three directions as well as the EPID + gantry sag by comparison to the reference gantry zero image. The algorithm results were then tested against independent methods. The method was applied to compare the effect in clockwise and counter clockwise gantry rotations and different source-to-detector distances (SDDs). The results were monitored for one linear accelerator over a course of 15 months and six other linear-accelerators from two treatment centers were also investigated using this method. The generalized shift patterns were derived from the data and used in an image registration algorithm to correct for the effect of the mechanical sag in the system. The Gamma evaluation (3%, 3 mm) technique was used to investigate the improvement in alignment of cine EPID images of a fixed field, by comparing both individual images and the sum of images in a series with the reference gantry zero image. The mechanical sag during gantry rotation was dependent on the gantry angle and was larger in the in-plane direction, although the patterns were not

  2. Methodology for relative location of voltage sag source using voltage measurements only

    Directory of Open Access Journals (Sweden)

    Jairo Blanco-Solano

    2015-01-01

    Full Text Available Este trabajo presenta una metodología para la localización rela tiva de las fuentes generadoras de hundimientos de tensión y la cual se basa únicamente en mediciones de tensión. Las fallas de red son las perturbaci ones más frecuentes en los sistemas eléctricos y son las causan tes del mayor número de hundimientos de tensión. Así , el algoritmo propuesto conside ra únicamente los hundimientos de tensión originados por fallas de red y requiere un mínimo de tres monitores de tensión para su aplicación. La cali dad de la potencia puede evaluar se automáticamente a través de la caracterización y extracción de información de los registros de tensión. Las tens iones de secuencia positiva son usadas como los descriptores pa ra determinar la localización relativa y la metodol ogía es aplicada en un caso d e estudio por simulación comproba ndo su efectividad. Para la va lidación de los resultados se usa Matlab, toman do como entradas los hundimiento s de tensión simula dos en ATP-EMTP.

  3. Pulsed voltage electrospray ion source and method for preventing analyte electrolysis

    Science.gov (United States)

    Kertesz, Vilmos [Knoxville, TN; Van Berkel, Gary [Clinton, TN

    2011-12-27

    An electrospray ion source and method of operation includes the application of pulsed voltage to prevent electrolysis of analytes with a low electrochemical potential. The electrospray ion source can include an emitter, a counter electrode, and a power supply. The emitter can include a liquid conduit, a primary working electrode having a liquid contacting surface, and a spray tip, where the liquid conduit and the working electrode are in liquid communication. The counter electrode can be proximate to, but separated from, the spray tip. The power system can supply voltage to the working electrode in the form of a pulse wave, where the pulse wave oscillates between at least an energized voltage and a relaxation voltage. The relaxation duration of the relaxation voltage can range from 1 millisecond to 35 milliseconds. The pulse duration of the energized voltage can be less than 1 millisecond and the frequency of the pulse wave can range from 30 to 800 Hz.

  4. A high voltage gain quasi Z-source isolated DC/DC converter

    DEFF Research Database (Denmark)

    Siwakoti, Yam P.; Blaabjerg, Frede; Loh, Poh Chiang

    2014-01-01

    A compact quasi-Z-source DC/DC converter is presented with high voltage gain, isolated output, and improved efficiency. The improvements in size and performance were achieved by using a square wave inverter with only two output switches driving an isolating transformer in push-pull mode, followed...... by a voltage doubling output rectifier. The converter is well-suited to applications requiring a high voltage gain, especially renewable energy sources such as photovoltaic and fuel-cell power supplies. To demonstrate the converter's performance a prototype designed to output 400 V at 500 W was constructed...

  5. A rationale for the observed non-linearity in pressure tube creep sag with time in service

    International Nuclear Information System (INIS)

    Sedran, P.J.

    2013-01-01

    In 2012, a paper was presented at the CNS SGC Conference which included an explanation for measured non-linear trends in Pressure Tube (PT) creep sag. The section of the 2012 paper covering this topic was revised and is presented as the main subject of this paper. The practical applications for the prediction of long-term Fuel Channel (FC) creep sag include the analysis of Calandria Tube - Liquid Injection Nozzle (CT-LIN) contact, and fuel passage and PT replacement assessments. The current practice for predicting FC creep sag in life cycle management applications is to use a linear model for creep sag versus time in service. However, PT sag measurements from the Point Lepreau Generating Station (PLGS) and Gentilly-2 (G-2) have displayed a non-linear trend with a creep sag rate that is decreasing with time in service. As an example, for PT F06 in PLGS, a 60% reduction in the nominal creep sag rate was observed for measurements taken 18 years apart. Subsequently, it was found that a 56% reduction in the creep sag rate for F06 over 18 years could be attributed to a fundamental geometric property of the PT creep sag profile. In addition, a further 1.6% decrease in the creep sag rate of the CT over the same period could be attributed to bending stress reductions due to the deformation of the CT. The resultant reduction in the PT creep sag rate for F06 was predicted to be 57.6%, closely matching the observed PT creep sag rate reduction of 60%. Therefore, this paper provides a rationale to explain the observed non-linear trends in PT creep sag, the use of which could benefit stations engaging in asset management as a means of FC life extension. This paper presents a summary of the worked performed to correlate the observed reductions in PT creep sag rate to the geometrical properties of the PT creep sag profile and the predicted bending stress reductions in the CT. (author)

  6. Voltage profile program for the Kennedy Space Center electric power distribution system

    Science.gov (United States)

    1976-01-01

    The Kennedy Space Center voltage profile program computes voltages at all busses greater than 1 Kv in the network under various conditions of load. The computation is based upon power flow principles and utilizes a Newton-Raphson iterative load flow algorithm. Power flow conditions throughout the network are also provided. The computer program is designed for both steady state and transient operation. In the steady state mode, automatic tap changing of primary distribution transformers is incorporated. Under transient conditions, such as motor starts etc., it is assumed that tap changing is not accomplished so that transformer secondary voltage is allowed to sag.

  7. Voltage Sags Ride-Through of Motion Sensorless Controlled PMSG for Wind Turbines

    DEFF Research Database (Denmark)

    Fatu, Marius; Lascu, Cristian; Andreescu, Gheorghe-Daniel

    2007-01-01

    This paper describes a variable-speed motion-sensorless permanent magnet synchronous generator (PMSG) control system for wind energy generation. The proposed system contains a PMSG connected to the grid by a back-to-back PWM inverter with bidirectional power flow, a line filter, and a transformer....... The control system employs PI current controllers with crosscoupling decoupling for both inverters, an active power controller, and a DC link voltage controller. The PMSG rotor speed without using emf integration, and the line voltage frequency are estimated by two PLL based observers. A Dmodule filter...

  8. The negative temperature coefficient resistivities of Ag2S-Ag core–shell structures

    International Nuclear Information System (INIS)

    Yu, Mingming; Liu, Dongzhi; Li, Wei; Zhou, Xueqin

    2014-01-01

    In this paper, the conductivity of silver nanoparticle films protected by 3-mercaptopropionic acid (Ag/MPA) has been investigated. When the nanoparticles were annealed in air at 200 °C, they converted to stable Ag 2 S-Ag core–shell structures. The mechanism for the formation of the Ag 2 S-Ag core–shell structures along with the compositional changes and the microstructural evolution of the Ag/MPA nanoparticles during the annealing process are discussed. It is proposed that the Ag 2 S-Ag core–shell structure was formed through a solid-state reduction reaction, in which the Ag + ions coming from Ag 2 S were reduced by sulfonate species and sulfur ions. The final Ag 2 S-Ag films display an exponentially decreased resistivity with increasing temperature from 25 to 170 °C. The negative temperature coefficient resistivity of Ag 2 S-Ag films can be adjusted by changing the S/Ag molar ratio used for the synthesis of the Ag/MPA nanoparticles, paving the way for the preparation of negative temperature-coefficient thermistors via printing technology for use in the electronics.

  9. Geophysical Prediction Technology Based on Organic Carbon Content in Source Rocks of the Huizhou Sag, the South China Sea

    Directory of Open Access Journals (Sweden)

    Yang Wei

    2017-08-01

    Full Text Available Due to the high exploration cost, limited number of wells for source rocks drilling and scarce test samples for the Total Organic Carbon Content (TOC in the Huizhou sag, the TOC prediction of source rocks in this area and the assessment of resource potentials of the basin are faced with great challenges. In the study of TOC prediction, predecessors usually adopted the logging assessment method, since the data is only confined to a “point” and the regional prediction of the source bed in the seismic profile largely depends on the recognition of seismic facies, making it difficult to quantify TOC. In this study, we combined source rock geological characteristics, logging and seismic response and built the mathematical relation between quasi TOC curve and seismic data based on the TOC logging date of a single well and its internal seismic attribute. The result suggested that it was not purely a linear relationship that was adhered to by predecessors, but was shown as a complicated non-linear relationship. Therefore, the neural network algorithm and SVMs were introduced to obtain the optimum relationship between the quasi TOC curve and the seismic attribute. Then the goal of TOC prediction can be realized with the method of seismic inversion.

  10. Investigation on a Novel Discontinuous Pulse-Width Modulation Algorithm for Single-phase Voltage Source Rectifier

    DEFF Research Database (Denmark)

    Qu, Hao; Yang, Xijun; Guo, Yougui

    2014-01-01

    Single-phase voltage source converter (VSC) is an important power electronic converter (PEC), including single-phase voltage source inverter (VSI), single-phase voltage source rectifier (VSR), single-phase active power filter (APF) and single-phase grid-connection inverter (GCI). Single-phase VSC...

  11. A study on the operation analysis of the power conditioning system with real HTS SMES coil

    International Nuclear Information System (INIS)

    Kim, A.R.; Jung, H.Y.; Kim, J.H.; Ali, Mohd. Hasan; Park, M.; Yu, I.K.; Kim, H.J.; Kim, S.H.; Seong, K.C.

    2008-01-01

    Voltage sag from sudden increasing loads is one of the major problems in the utility network. In order to compensate the voltage sag problem, power compensation devices have widely been developed. In the case of voltage sag, it needs an energy source to overcome the energy caused by voltage sag. According as the SMES device is characterized by its very high response time of charge and discharge, it has widely been researched and developed for more than 20 years. However, before the installation of SMES into utility, the system analysis has to be carried out with a certain simulation tool. This paper presents a real-time simulation algorithm for the SMES system by using the miniaturized SMES model coil whose properties are same as those of real size SMES coil. With this method, researchers can easily analyse the performance of SMES connected into utility network by abstracting the properties from the real modeled SMES coil and using the virtual simulated power network in RSCAD/RTDS

  12. PV source based high voltage gain current fed converter

    Science.gov (United States)

    Saha, Soumya; Poddar, Sahityika; Chimonyo, Kudzai B.; Arunkumar, G.; Elangovan, D.

    2017-11-01

    This work involves designing and simulation of a PV source based high voltage gain, current fed converter. It deals with an isolated DC-DC converter which utilizes boost converter topology. The proposed converter is capable of high voltage gain and above all have very high efficiency levels as proved by the simulation results. The project intends to produce an output of 800 V dc from a 48 V dc input. The simulation results obtained from PSIM application interface were used to analyze the performance of the proposed converter. Transformer used in the circuit steps up the voltage as well as to provide electrical isolation between the low voltage and high voltage side. Since the converter involves high switching frequency of 100 kHz, ultrafast recovery diodes are employed in the circuitry. The major application of the project is for future modeling of solar powered electric hybrid cars.

  13. Immunogenic Eimeria tenella glycosylphosphatidylinositol-anchored surface antigens (SAGs induce inflammatory responses in avian macrophages.

    Directory of Open Access Journals (Sweden)

    Yock-Ping Chow

    Full Text Available At least 19 glycosylphosphatidylinositol (GPI-anchored surface antigens (SAGs are expressed specifically by second-generation merozoites of Eimeria tenella, but the ability of these proteins to stimulate immune responses in the chicken is unknown.Ten SAGs, belonging to two previously defined multigene families (A and B, were expressed as soluble recombinant (r fusion proteins in E. coli. Chicken macrophages were treated with purified rSAGs and changes in macrophage nitrite production, and in mRNA expression profiles of inducible nitric oxide synthase (iNOS and of a panel of cytokines were measured. Treatment with rSAGs 4, 5, and 12 induced high levels of macrophage nitric oxide production and IL-1β mRNA transcription that may contribute to the inflammatory response observed during E. tenella infection. Concomitantly, treatment with rSAGs 4, 5 and 12 suppressed the expression of IL-12 and IFN-γ and elevated that of IL-10, suggesting that during infection these molecules may specifically impair the development of cellular mediated immunity.In summary, some E. tenella SAGs appear to differentially modulate chicken innate and humoral immune responses and those derived from multigene family A (especially rSAG 12 may be more strongly linked with E. tenella pathogenicity associated with the endogenous second generation stages.

  14. Voltage resonant inverter as a power source

    OpenAIRE

    Lupenko, Anatoliy; Stakhiv, Petro

    2014-01-01

    The operation mode of a voltage resonant inverter as a power source with variable load is analyzed. In order to reduce load power variations, an approach to development of the inverter’s load power response based on providing similar positive and negative power deviations from its nominal value has been proposed. The design procedure for resonant inverter with open loop structure as a power source has been elaborated. For a high pressure sodium lamp as a load, the power deviation of about 4% ...

  15. Interconnected High-Voltage Pulsed-Power Converters System Design for H− Ion Sources

    CERN Document Server

    Aguglia, D

    2014-01-01

    This paper presents the design and experimental validations of a system of three new high-voltage (HV) pulsedpower converters for the H− sources. The system requires three pulsed voltages (50, 40, and 25 kV to ground) at 2-Hz repetition rate, for 700 μs of usable flat-top. The solution presents ripplefree output voltages and minimal stored energy to protect the ion source from the consequences of arc events. Experimental results on the final full-scale prototype are presented. In case of short-circuit events, the maximal energy delivered to the source is in the Joule range. HV flat-top stability of 1% is experimentally achieved with a simple Proportional-Integral- Derivative regulation and preliminary tuned H− source (e.g., radio frequency control, gas injection, and so forth). The system is running since more than a year with no power converter failures and damage to the source.

  16. Apparatus with a cooled X-ray source and a high voltage generator

    Energy Technology Data Exchange (ETDEWEB)

    1977-02-01

    Apparatus, especially for a dental application, with an X-ray source and a high voltage generator, whereby the X-ray source and a high voltage generator are contained in a housing, which is filled with a coolant medium, characterised by the housing being divided into two chambers, whereby the X-ray source is in the first chamber and the high voltage generator is in the second chamber and between the chambers a dividing wall is placed for the screening of the X-ray irradiation from the first chamber from the second, whereby at least one of the walls of the second chamber is elastic to accommodate the expansion of the coolant medium.

  17. Novel T-Z source inverter with high voltage gain and reduced transformer turn ratio

    DEFF Research Database (Denmark)

    Mostaan, Ali; Sharifi Malfejani, Saeed; Soltani, Mohsen

    2015-01-01

    Novel voltage source inverter based on the Z source inverter structure is introduced in this paper. In this new inverter, two inductors of the impedance network in conventional Z source inverter are replaced with two transformers or coupled inductors, but unlike the T-Z source inverter that it......'s voltage gain is raised with increasing the transformers turn ratio, the voltage gain in the proposed inverter is raised with lowering the transformer turn ratio. Therefore, transformers with lower turn ratio are required in the proposed inverter in compare with T- Z source inverter that can lead to lower...

  18. CARACTERIZACIÓN DE LUMINARIAS TIPO HALURO METÁLICO ANTE EVENTOS SAG

    Directory of Open Access Journals (Sweden)

    Bonie Johana Restrepo Cuestas

    Full Text Available Este artículo plantea una metodología para la caracterización de luminarias de haluro metálico, ante eventos sag. Inicialmente, se diseñó y construyó un generador de eventos sag. Luego, se planteó un esquema de pruebas, que fue utilizado para analizar el comportamiento de un tipo de luminarias de alta densidad de descarga tipo Metal Halide, ante eventos sag. Finalmente, tomando como referente el estándar SEMI F-47, se realizó la construcción de una curva característica que muestra la región de operación de la luminaria.

  19. A Comparison Study of Sinusoidal PWM and Space Vector PWM Techniques for Voltage Source Inverter

    Directory of Open Access Journals (Sweden)

    Ömer Türksoy

    2017-06-01

    Full Text Available In this paper, the methods used to control voltage source inverters which have been intensively investigated in recent years are compared. Although the most efficient result is obtained with the least number of switching elements in the inverter topologies, the method used in the switching is at least as effective as the topology. Besides, the selected switching method to control the inverter will play an effective role in suppressing harmonic components while producing the ideal output voltage. There are many derivatives of pulse width modulation techniques that are commonly used to control voltage source inverters. Some of widespread methods are sinusoidal pulse width modulation and space vector pulse width modulation techniques. These modulation techniques used for generating variable frequency and amplitude output voltage in voltage source inverters, have been simulated by using MATLAB/SIMULINK. And, the total harmonic distortions of the output voltages are compared. As a result of simulation studies, sinusoidal pulse width modulation has been found to have more total harmonic distortion in output voltages of voltage source inverters in the simulation. Space vector pulse width modulation has been shown to produce a more efficient output voltage with less total harmonic distortion.

  20. Gravity sag of sandwich panel assemblies as applied to precision cathode strip chamber structural design

    International Nuclear Information System (INIS)

    Horvath, J.

    1993-01-01

    The relationship between gravity sag of a precision cathode strip chamber and its sandwich panel structural design is explored parametrically. An algorithm for estimating the dominant component of gravity sag is defined. Graphs of normalized gravity sag as a function of gap frame width and material, sandwich core edge filler width and material, panel skin thickness, gap height, and support location are calculated using the gravity sag algorithm. The structural importance of the sandwich-to-sandwich ''gap frame'' connection is explained

  1. Improved detection of equine antibodies against Sarcocystis neurona using polyvalent ELISAs based on the parasite SnSAG surface antigens.

    Science.gov (United States)

    Yeargan, Michelle R; Howe, Daniel K

    2011-02-28

    Equine protozoal myeloencephalitis (EPM) is a common neurologic disease of horses that is caused by the apicomplexan pathogen Sarcocystis neurona. To help improve serologic diagnosis of S. neurona infection, we have modified existing enzyme-linked immunosorbent assays (ELISAs) based on the immunogenic parasite surface antigens SnSAG2, SnSAG3, and SnSAG4 to make the assays polyvalent, thereby circumventing difficulties associated with parasite antigenic variants and diversity in equine immune responses. Two approaches were utilized to achieve polyvalence: (1) mixtures of the individual recombinant SnSAGs (rSnSAGs) were included in single ELISAs; (2) a collection of unique SnSAG chimeras that fused protein domains from different SnSAG surface antigens into a single recombinant protein were generated for use in the ELISAs. These new assays were assessed using a defined sample set of equine sera and cerebrospinal fluids (CSFs) that had been characterized by Western blot and/or were from confirmed EPM horses. While all of the polyvalent ELISAs performed relatively well, the highest sensitivity and specificity (100%/100%) were achieved with assays containing the rSnSAG4/2 chimera (Domain 1 of SnSAG4 fused to SnSAG2) or using a mixture of rSnSAG3 and rSnSAG4. The rSnSAG4 antigen alone and the rSnSAG4/3 chimera (Domain 1 of SnSAG4 fused to Domain 2 of SnSAG3) exhibited the next best accuracy at 95.2% sensitivity and 100% specificity. Binding ratios and percent positivity (PP) ratios, determined by comparing the mean values for positive versus negative samples, showed that the most advantageous signal to noise ratios were provided by rSnSAG4 and the rSnSAG4/3 chimera. Collectively, our results imply that a polyvalent ELISA based on SnSAG4 and SnSAG3, whether as a cocktail of two proteins or as a single chimeric protein, can give optimal results in serologic testing of serum or CSF for the presence of antibodies against S. neurona. The use of polyvalent SnSAG ELISAs will

  2. Variable speed wind turbine generator system with current controlled voltage source inverter

    International Nuclear Information System (INIS)

    Muyeen, S.M.; Al-Durra, Ahmed; Tamura, J.

    2011-01-01

    highlights: → Current controlled voltage source inverter scheme for wind power application. → Low voltage ride through of wind farm. → Variable speed wind turbine driven permanent magnet synchronous generator-operation and control. -- Abstract: The present popular trend of wind power generation is to use variable speed wind turbine (VSWT) driving a doubly fed induction generator (DFIG), wound field synchronous generator (WFSG) or permanent magnet synchronous generator (PMSG). Among them, stability analyses of DFIG type of VSWT have already been reported in many literatures. However, transient stability and low voltage ride through (LVRT) characteristics analyses for synchronous generator type of VSWT is not sufficient enough. This paper focuses on detailed LVRT characteristic analysis of variable speed wind turbine driving a PMSG (VSWT-PMSG) with current controlled voltage source inverter (CC-VSI). Modeling and suitable control strategies for overall system are developed to augment the low voltage ride through capability of variable speed wind generator, considering recent wind farm grid code. Both symmetrical and unsymmetrical faults are analyzed as network disturbances in this paper. The permanent fault due to unsuccessful reclosing of circuit breakers is taken into consideration, which is a salient feature of this study. Moreover, the dynamic characteristic is analyzed using real wind speed data measured in Hokkaido Island, Japan. The proposed control scheme is simulated by using the standard power system simulation package PSCAD/EMTDC and results are verified by comparing that of voltage controlled voltage source inverter scheme available in power system literature.

  3. Variable speed wind turbine generator system with current controlled voltage source inverter

    Energy Technology Data Exchange (ETDEWEB)

    Muyeen, S.M., E-mail: muyeen0809@yahoo.co [Dept. of Electrical Engineering, Petroleum Institute, P.O. Box 2533, Abu Dhabi (United Arab Emirates); Al-Durra, Ahmed [Dept. of Electrical Engineering, The Petroleum Institute, P.O. Box 2533, Abu Dhabi (United Arab Emirates); Tamura, J. [Dept. of EEE, Kitami Institute of Technology, 165 Koen-cho, Kitami 090-8507 (Japan)

    2011-07-15

    highlights: {yields} Current controlled voltage source inverter scheme for wind power application. {yields} Low voltage ride through of wind farm. {yields} Variable speed wind turbine driven permanent magnet synchronous generator-operation and control. -- Abstract: The present popular trend of wind power generation is to use variable speed wind turbine (VSWT) driving a doubly fed induction generator (DFIG), wound field synchronous generator (WFSG) or permanent magnet synchronous generator (PMSG). Among them, stability analyses of DFIG type of VSWT have already been reported in many literatures. However, transient stability and low voltage ride through (LVRT) characteristics analyses for synchronous generator type of VSWT is not sufficient enough. This paper focuses on detailed LVRT characteristic analysis of variable speed wind turbine driving a PMSG (VSWT-PMSG) with current controlled voltage source inverter (CC-VSI). Modeling and suitable control strategies for overall system are developed to augment the low voltage ride through capability of variable speed wind generator, considering recent wind farm grid code. Both symmetrical and unsymmetrical faults are analyzed as network disturbances in this paper. The permanent fault due to unsuccessful reclosing of circuit breakers is taken into consideration, which is a salient feature of this study. Moreover, the dynamic characteristic is analyzed using real wind speed data measured in Hokkaido Island, Japan. The proposed control scheme is simulated by using the standard power system simulation package PSCAD/EMTDC and results are verified by comparing that of voltage controlled voltage source inverter scheme available in power system literature.

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

    Science.gov (United States)

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

    2016-12-13

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

  5. SagE induces highly effective protective immunity against Streptococcus iniae mainly through an immunogenic domain in the extracellular region.

    Science.gov (United States)

    Sun, Yun; Sun, Li; Xing, Ming-qing; Liu, Chun-sheng; Hu, Yong-hua

    2013-11-12

    Streptococcus iniae is a Gram-positive bacterium and a severe pathogen of a wide range of farmed fish. S. iniae possesses a virulence-associated streptolysin S cluster composed of several components, one of which is SagE. SagE a transmembrane protein with one major extracellular region named ECR. This study aimed to develop a SagE-based DNA candidate vaccine against streptococcosis and examine the immunoprotective mechanism of the vaccine. We constructed a DNA vaccine, pSagE, based on the sagE gene and examined its immunological property in a Japanese flounder (Paralichthys olivaceus) model. The results showed that at 7 days post-vaccination, expression of SagE at transcription and translation levels was detected in the tissues of the vaccinated fish. After challenge with S. iniae at one and two months post-vaccination, pSagE-vaccinated fish exhibited relative percent survival (RPS) of 95% and 88% respectively. Immunological analysis showed that (i) pSagE significantly upregulated the expression of a wide range of immune genes, (ii) pSagE induced the production of specific serum antibodies that bound whole-cell S. iniae, and (iii) treatment of S. iniae with pSagE-induced antibodies blocked bacterial invasion of host cells. To localize the immunoprotective domain of SagE, the ECR-expressing DNA vaccine pSagEECR was constructed. Immunization analysis showed that flounder vaccinated with pSagEECR exhibited a RPS of 68%, and that pSagEECR induced serum antibody production and immune gene expression in a manner similar to, though to lower magnitudes than, those induced by pSagE. We in this study developed a DNA vaccine, pSagE, which induces highly protective immunity against S. iniae. The protective effect of pSagE is probably due to its ability to elicit systemic immune response, in particular that of the humoral branch, which leads to production of specific serum antibodies that impair bacterial infection. These results add insights to the immunoprotective mechanism

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

    International Nuclear Information System (INIS)

    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

  7. Inverter for Interchangeable Use as Current Source Inverter and Voltage Source Inverter for Interconnecting to Grid

    Science.gov (United States)

    Teruya, Daisuke; Masukawa, Shigeo; Iida, Shoji

    We propose a novel inverter that can be operated either as a Current Source Inverter (CSI) or as a Voltage Source Inverter (VSI) by changing only the control signals. It is proper to apply it to the interconnecting system with renewal energy, such as photovoltaic cells or wind generation systems, to a grid. This inverter is usually operated as the CSI connected to the grid. Even if the energy source has a lower voltage than the grid, the energy can be supplied to the grid through the proposed inverter. The power factor can be briefly maintained at almost unity. When power supply from the grid is interrupted, the proposed circuit should be operated as the VSI in the stand-alone operation mode. In this way, the circuit can maintain a constant output voltage to the loads. In this paper, the proposed circuit configuration and the control schemes for both the CSI and the VSI are described. Further, the circuit characteristics for both are discussed experimentally.

  8. Investigation of Grid-connected Voltage Source Converter Performance under Unbalanced Faults

    DEFF Research Database (Denmark)

    Jia, Jundi; Yang, Guangya; Nielsen, Arne Hejde

    2016-01-01

    Renewable energy sources (RES) and HVDC links are typically interfaced with the grid by power converters, whose performance during grid faults is significantly different from that of traditional synchronous generators. This paper investigates the performance of grid-connected voltage source...... that the performance of VSCs varies with their control strategies. Negative-sequence current control is necessary to restrict converter current in each phase under unbalanced faults. Among presented control strategies, the balanced current control strategy complies with the present voltage support requirement best...

  9. Hydrocarbon migration and accumulation in the Upper Cretaceous Qingshankou Formation, Changling Sag, southern Songliao Basin: Insights from integrated analyses of fluid inclusion, oil source correlation and basin modelling

    Science.gov (United States)

    Dong, Tian; He, Sheng; Wang, Dexi; Hou, Yuguang

    2014-08-01

    The Upper Cretaceous Qingshankou Formation acts as both the source and reservoir sequence in the Changling Sag, situated in the southern end of the Songliao Basin, northeast China. An integrated approach involving determination of hydrocarbon charging history, oil source correlation and hydrocarbon generation dynamic modeling was used to investigate hydrocarbon migration processes and further predict the favorable targets of hydrocarbon accumulations in the Qingshankou Formation. The hydrocarbon generation and charge history was investigated using fluid inclusion analysis, in combination with stratigraphic burial and thermal modeling. The source rocks began to generate hydrocarbons at around 82 Ma and the hydrocarbon charge event occurred from approximately 78 Ma to the end of Cretaceous (65.5 Ma) when a large tectonic uplift took place. Correlation of stable carbon isotopes of oils and extracts of source rocks indicates that oil was generated mainly from the first member of Qingshankou Formation (K2qn1), suggesting that hydrocarbon may have migrated vertically. Three dimensional (3D) petroleum system modeling was used to evaluate the processes of secondary hydrocarbon migration in the Qingshankou Formation since the latest Cretaceous. During the Late Cretaceous, hydrocarbon, mainly originated from the Qianan depression, migrated laterally to adjacent structural highs. Subsequent tectonic inversion, defined as the late Yanshan Orogeny, significantly changed hydrocarbon migration patterns, probably causing redistribution of primary hydrocarbon reservoirs. In the Tertiary, the Heidimiao depression was buried much deeper than the Qianan depression and became the main source kitchen. Hydrocarbon migration was primarily controlled by fluid potential and generally migrated from relatively high potential areas to low potential areas. Structural highs and lithologic transitions are potential traps for current oil and gas exploration. Finally, several preferred hydrocarbon

  10. The SnSAG merozoite surface antigens of Sarcocystis neurona are expressed differentially during the bradyzoite and sporozoite life cycle stages.

    Science.gov (United States)

    Gautam, A; Dubey, J P; Saville, W J; Howe, D K

    2011-12-29

    Sarcocystis neurona is a two-host coccidian parasite whose complex life cycle progresses through multiple developmental stages differing at morphological and molecular levels. The S. neurona merozoite surface is covered by multiple, related glycosylphosphatidylinositol-linked proteins, which are orthologous to the surface antigen (SAG)/SAG1-related sequence (SRS) gene family of Toxoplasma gondii. Expression of the SAG/SRS proteins in T. gondii and another related parasite Neospora caninum is life-cycle stage specific and seems necessary for parasite transmission and persistence of infection. In the present study, the expression of S. neurona merozoite surface antigens (SnSAGs) was evaluated in the sporozoite and bradyzoite stages. Western blot analysis was used to compare SnSAG expression in merozoites versus sporozoites, while immunocytochemistry was performed to examine expression of the SnSAGs in merozoites versus bradyzoites. These analyses revealed that SnSAG2, SnSAG3 and SnSAG4 are expressed in sporozoites, while SnSAG5 was appeared to be downregulated in this life cycle stage. In S. neurona bradyzoites, it was found that SnSAG2, SnSAG3, SnSAG4 and SnSAG5 were either absent or expression was greatly reduced. As shown for T. gondii, stage-specific expression of the SnSAGs may be important for the parasite to progress through its developmental stages and complete its life cycle successfully. Thus, it is possible that the SAG switching mechanism by these parasites could be exploited as a point of intervention. As well, the alterations in surface antigen expression during different life cycle stages may need to be considered when designing prospective approaches for protective vaccination. Copyright © 2011 Elsevier B.V. All rights reserved.

  11. Impedance-based Analysis of DC Link Control in Voltage Source Rectifiers

    DEFF Research Database (Denmark)

    Lu, Dapeng; Wang, Xiongfei; Blaabjerg, Frede

    2018-01-01

    This paper analyzes the dynamics influences of the outer dc link control in the voltage source rectifiers based on the impedance model. The ac-dc interactions are firstly presented by means of full order small signal model in dq frame, which shows the input voltage and load condition are the two...

  12. Low voltage ride-through capability control for single-stage inverter-based grid-connected photovoltaic power plant

    DEFF Research Database (Denmark)

    Al-Shetwi, Ali Q.; Sujod, Muhamad Zahim; Blaabjerg, Frede

    2018-01-01

    and current limiter are used to absorb the excessive dc-voltage and limits excessive ac current, respectively. This control strategy can also ensure the reactive power support through the injection of reactive current according to the standard requirements as soon as the voltage sag is detected. Furthermore...... to improve the capability of ride-through fault safely and keep the inverter connected, but also to provide grid support through active and reactive power control at different type of faults....

  13. Shunt PWM advanced var compensators based on voltage source inverters for Facts applications

    Energy Technology Data Exchange (ETDEWEB)

    Barbosa, Pedro G; Misaka, Isamu; Watanabe, Edson H [Universidade Federal, Rio de Janeiro, RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia

    1994-12-31

    Increased attention has been given to improving power system operation. This paper presents modeling, analysis and design of reactive shunt power compensators based on PWM-Voltage Source Inverters (Pulse Width Modulation -Voltage Source Inverters). (Pulse Width Modulation - Voltage Source Inverters). The control algorithm is based on new concepts of instantaneous active and reactive power theory. The objective is to show that with a small capacitor in the side of a 3-phase PWM-VSI it is possible to synthesize a variable reactive (capacitive or inductive) device. Design procedures and experimental results are presented. The feasibility of this method was verified by digital simulations and measurements on a small scale model. (author) 9 refs., 12 figs.

  14. Antigenic evaluation of a recombinant baculovirus-expressed Sarcocystis neurona SAG1 antigen.

    Science.gov (United States)

    Gupta, G D; Lakritz, J; Saville, W J; Livingston, R S; Dubey, J P; Middleton, J R; Marsh, A E

    2004-10-01

    Sarcocystis neurona is the primary parasite associated with equine protozoal myeloencephalitis (EPM). This is a commonly diagnosed neurological disorder in the Americas that infects the central nervous system of horses. Current serologic assays utilize culture-derived parasites as antigen. This method requires large numbers of parasites to be grown in culture, which is labor intensive and time consuming. Also, a culture-derived whole-parasite preparation contains conserved antigens that could cross-react with antibodies against other Sarcocystis species and members of Sarcocystidae such as Neospora spp., Hammondia spp., and Toxoplasma gondii. Therefore, there is a need to develop an improved method for the detection of S. neurona-specific antibodies. The sera of infected horses react strongly to surface antigen 1 (SnSAG1), an approximately 29-kDa protein, in immunoblot analysis, suggesting that it is an immunodominant antigen. The SnSAG1 gene of S. neurona was cloned, and recombinant S. neurona SAG1 protein (rSnSAG1-Bac) was expressed with the use of a baculovirus system. By immunoblot analysis, the rSnSAG1-Bac antigen detected antibodies to S. neurona from naturally infected and experimentally inoculated equids, cats, rabbit, mice, and skunk. This is the first report of a baculovirus-expressed recombinant S. neurona antigen being used to detect anti-S. neurona antibodies in a variety of host species.

  15. 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...... is introduced in the controller, which is necessary in order to reduce the dc-bus voltage ripple and active power harmonics at the same time. The proposed control topology is implemented in the lab. Simulation and experimental results are provided to validate its performance and the analysis presented...

  16. Analysis of loss distribution of Conventional Boost, Z-source and Y-source Converters for wide power and voltage range

    DEFF Research Database (Denmark)

    Gadalla, Brwene Salah Abdelkarim; Schaltz, Erik; Siwakoti, Yam Prasad

    2017-01-01

    Boost converters are needed in many applications which require the output voltage to be higher than the input voltage. Recently, boost type converters have been applied for industrial applications, and hence it has become an interesting topic of research. Many researchers proposed different...... impedance source converters with their unique advantages as having a high voltage gain in a small range of duty cycle ratio. However, the thermal behaviour of the semiconductor devices and passive elements in the impedance source converter is an important issue from a reliability point of view and it has...... not been investigated yet. Therefore, this paper presents a comparison between the conventional boost, the Z-source, and the Y-source converters based on a thermal evaluation of the semiconductors. In addition, the three topologies are also compared with respect to their efficiency. In this study...

  17. Modeling and reliability analysis of three phase z-source AC-AC converter

    Directory of Open Access Journals (Sweden)

    Prasad Hanuman

    2017-12-01

    Full Text Available This paper presents the small signal modeling using the state space averaging technique and reliability analysis of a three-phase z-source ac-ac converter. By controlling the shoot-through duty ratio, it can operate in buck-boost mode and maintain desired output voltage during voltage sag and surge condition. It has faster dynamic response and higher efficiency as compared to the traditional voltage regulator. Small signal analysis derives different control transfer functions and this leads to design a suitable controller for a closed loop system during supply voltage variation. The closed loop system of the converter with a PID controller eliminates the transients in output voltage and provides steady state regulated output. The proposed model designed in the RT-LAB and executed in a field programming gate array (FPGA-based real-time digital simulator at a fixedtime step of 10 μs and a constant switching frequency of 10 kHz. The simulator was developed using very high speed integrated circuit hardware description language (VHDL, making it versatile and moveable. Hardware-in-the-loop (HIL simulation results are presented to justify the MATLAB simulation results during supply voltage variation of the three phase z-source ac-ac converter. The reliability analysis has been applied to the converter to find out the failure rate of its different components.

  18. Direct model-based predictive control scheme without cost function for voltage source inverters with reduced common-mode voltage

    Science.gov (United States)

    Kim, Jae-Chang; Moon, Sung-Ki; Kwak, Sangshin

    2018-04-01

    This paper presents a direct model-based predictive control scheme for voltage source inverters (VSIs) with reduced common-mode voltages (CMVs). The developed method directly finds optimal vectors without using repetitive calculation of a cost function. To adjust output currents with the CMVs in the range of -Vdc/6 to +Vdc/6, the developed method uses voltage vectors, as finite control resources, excluding zero voltage vectors which produce the CMVs in the VSI within ±Vdc/2. In a model-based predictive control (MPC), not using zero voltage vectors increases the output current ripples and the current errors. To alleviate these problems, the developed method uses two non-zero voltage vectors in one sampling step. In addition, the voltage vectors scheduled to be used are directly selected at every sampling step once the developed method calculates the future reference voltage vector, saving the efforts of repeatedly calculating the cost function. And the two non-zero voltage vectors are optimally allocated to make the output current approach the reference current as close as possible. Thus, low CMV, rapid current-following capability and sufficient output current ripple performance are attained by the developed method. The results of a simulation and an experiment verify the effectiveness of the developed method.

  19. Commercial Building Motor Protection Response Report

    Energy Technology Data Exchange (ETDEWEB)

    James, Daniel P. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Kueck, John [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-06-17

    When voltages recover, motors may immediately reenergize and reaccelerate, or delay for a few minutes, or stay stalled. The estimated motor response is given for both the voltage sag magnitude and voltage sag duration. These response estimates are based on experience and available test data. Good data is available for voltage sag response for many components such as relays and contactors, but little data is available for both voltage sag and recovery response. The tables in Appendix A include data from recent voltage sag and recovery tests performed by SCE and BPA on air conditioners and energy management systems. The response of the motor can vary greatly depending on the type of protection and control. The time duration for the voltage sag consists of those times that are of interest for bulk power system modelers.

  20. Parallel operation of voltage-source converters: issues and applications

    Energy Technology Data Exchange (ETDEWEB)

    Almeida, F.C.B.; Silva, D.S. [Federal University of Juiz de Fora (UFJF), MG (Brazil)], Emails: felipe.brum@engenharia.ufjf.br, salomaoime@yahoo.com.br; Ribeiro, P.F. [Calvin College, Grand Rapids, MI (United States); Federal University of Juiz de Fora (UFJF), MG (Brazil)], E-mail: pfribeiro@ieee.org

    2009-07-01

    Technological advancements in power electronics have prompted the development of advanced AC/DC conversion systems with high efficiency and flexible performance. Among these devices, the Voltage-Source Converter (VSC) has become an essential building block. This paper considers the parallel operation of VSCs under different system conditions and how they can assist the operation of highly complex power networks. A multi-terminal VSC-based High Voltage Direct Current (M-VSC-HVDC) system is chosen to be modeled, simulated and then analyzed as an example of VSCs operating in parallel. (author)

  1. Salivary agglutinin/DMBT1SAG expression is up-regulated in the presence of salivary gland tumors

    DEFF Research Database (Denmark)

    Bikker, F J; van der Wal, J E; Ligtenberg, A J M

    2004-01-01

    Salivary agglutinin (SAG) is encoded by the gene Deleted in Malignant Brain Tumors 1 (DMBT1) and represents the salivary variant of DMBT1 (DMBT1(SAG)). While SAG is a bona fide anti-caries factor, DMBT1 was proposed as a candidate tumor-suppressor for brain, digestive tract, and lung cancer. Thou...

  2. Improvement the Capacity of Cockcroft-Walton High Voltage Source from 300 kV/20 mA to 500 kV/20 mA for Accelerating Voltage of Electron Beam Machine

    International Nuclear Information System (INIS)

    Suprapto; Djasiman

    2002-01-01

    The improvement capacity of Cockcroft-Walton high voltage source from 300 kV/20 mA to 500 kV/mA has been carrying out. To improve the capacity of high voltage source was done by means of increasing the stage number of voltage multiplier from 11 to 18 and its output voltage measuring resistance. Each stage of voltage multiplier consists of 2 capacitors and 2 circuits of high voltage diode. This voltage multiplier is constructed using main components of high voltage capacitor and high voltage diode each of 0.22 μF/50 kV and UF 5408 respectively. To avoid stray discharge and corona it was provided with high voltage electrode and corona ring. The test result indicated that the output voltage obtained from 16 stages was 350 kV according to operating condition of 25 MΩ resistive load and first stage voltage of 28.5 kV with oscillator frequency of 24 Hz. That condition requires anode voltage and current of 5.5 kV and 2.5 A respectively. The no load test for 16 stages indicates 400 kV of output voltage and 28.5 kV first stage voltage. Efficiency of high voltage source was 48 % at 6.75 kW of output power. The expected test of 500 kV with 18 stages of voltage multiplier can not be carried out because of some restrictive of loading system. From the test result can be predicted that the output voltage of 500 kV with 18 stages of voltage multiplier requires 31.2 kV of first stage voltage. Then the expected high voltage source of Cockcroft-Walton is capable as accelerating voltage source for Electron Beam Machine with energy of 500 kV. (author)

  3. Energy storage and alternatives to improve train voltage on a mass transit system

    Science.gov (United States)

    Gordon, S. P.; Rorke, W. S.

    1995-04-01

    The wide separation of substations in the Bay Area Rapid Transit system's transbay tunnel contributes to voltage sag when power demand is high. In the future, expansions to the system will exacerbate this problem by increasing traffic density. Typically, this situation is remedied through the installation of additional substations to increase the system's power capacity. We have evaluated the efficacy of several alternatives to this approach - specifically, installation of an 8 megajoule energy storage system, modification of the existing substations, or reduction of the resistance of the running rails or the third rail. To support this analysis, we have developed a simple model of the traction power system in the tunnel. We have concluded that the storage system does not have sufficient capacity to deal with the expected voltage sags; in this application, the alternatives present more effective solutions. We have also investigated the potential impact of these system upgrades on expected future capital outlays by BART for traction power infrastructure additions. We have found that rail or substation upgrades may reduce the need for additional substations. These upgrades may also be effective on other parts of the BART system and on other traction power systems.

  4. High-voltage transistor converter for pulsed x-ray sources

    International Nuclear Information System (INIS)

    Krasil'nikov, S.B.; Kristalinskii, A.L.; Lozovoi, L.N.; Markov, S.N.; Sindalovskii, E.I.

    1986-01-01

    A 24-V/12-kV converter for MIRA-2D and NORA pulsed x-ray sources is described. When the low-voltage supply varies within 20-26 V, the frequency stability of the x-ray pulses is higher by a factor of 3 ≅ 3 than when the PRIMA converter is used. For 14-24 V, the average output power of the converter is independent of the load impedance and increases linearly with an increase in supply voltage. The efficiency of the converter reaches 60%. The converter operates in the temperature range of -40 to +60 0 C

  5. Induced over voltage test on transformers using enhanced Z-source inverter based circuit

    Science.gov (United States)

    Peter, Geno; Sherine, Anli

    2017-09-01

    The normal life of a transformer is well above 25 years. The economical operation of the distribution system has its roots in the equipments being used. The economy being such, that it is financially advantageous to replace transformers with more than 15 years of service in the second perennial market. Testing of transformer is required, as its an indication of the extent to which a transformer can comply with the customers specified requirements and the respective standards (IEC 60076-3). In this paper, induced over voltage testing on transformers using enhanced Z source inverter is discussed. Power electronic circuits are now essential for a whole array of industrial electronic products. The bulky motor generator set, which is used to generate the required frequency to conduct the induced over voltage testing of transformers is nowadays replaced by static frequency converter. First conventional Z-source inverter, and second an enhanced Z source inverter is being used to generate the required voltage and frequency to test the transformer for induced over voltage test, and its characteristics is analysed.

  6. A new trivalent SnSAG surface antigen chimera for efficient detection of antibodies against Sarcocystis neurona and diagnosis of equine protozoal myeloencephalitis.

    Science.gov (United States)

    Yeargan, Michelle; de Assis Rocha, Izabela; Morrow, Jennifer; Graves, Amy; Reed, Stephen M; Howe, Daniel K

    2015-05-01

    Enzyme-linked immunosorbent assays (ELISAs) based on the SnSAG surface antigens of Sarcocystis neurona provide reliable detection of infection by the parasite. Moreover, accurate serodiagnosis of equine protozoal myeloencephalitis (EPM) is achieved with the SnSAG ELISAs by measuring antibodies in serum and cerebrospinal fluid (CSF) to reveal active infection in the central nervous system. Two independent ELISAs based on recombinant (r)SnSAG2 or a chimeric fusion of SnSAG3 and SnSAG4 (rSnSAG4/3) are currently used together for EPM serodiagnosis to overcome varied antibody responses in different horses. To achieve reliable antibody detection with a single ELISA instead of 2 separate ELISAs, rSnSAG2 was fused with rSnSAG4/3 into a single trivalent protein, designated rSnSAG2/4/3. Paired serum and CSF from 163 horses were tested with all 3 ELISAs. When the consensus antibody titers obtained with the rSnSAG2 and rSnSAG4/3 ELISAs were compared to the single SAG2/4/3 ELISA titers, Spearman rank correlation coefficients of ρ = 0.74 and ρ = 0.90 were obtained for serum and CSF, respectively, indicating strong agreement between the tests. When the rSnSAG2 and rSnSAG4/3 consensus serum-to-CSF titer ratio was compared to the rSnSAG2/4/3 serum-to-CSF titer ratio, the Spearman correlation coefficient was ρ = 0.87, again signifying strong agreement. Importantly, comparing the diagnostic interpretation of the serum-to-CSF titer ratios yielded a Cohen kappa value of 0.77. These findings suggest that the single ELISA based on the trivalent rSnSAG2/4/3 will provide serologic and diagnostic results that are highly comparable to the consensus of the 2 independent ELISAs based on rSnSAG2 and rSnSAG4/3. © 2015 The Author(s).

  7. Shootthrough fault protection system for bipolar transistors in a voltage source transistor inverter

    International Nuclear Information System (INIS)

    Wirth, W.F.

    1982-01-01

    Faulted bipolar transistors in a voltage source transistor inverter are protected against shootthrough fault current, from the filter capacitor of the d-c voltage source which drives the inverter over the d-c bus, by interposing a small choke in series with the filter capacitor to limit the rate of rise of that fault current while at the same time causing the d-c bus voltage to instantly drop to essentially zero volts at the beginning of a shootthrough fault. In this way, the load lines of the faulted transistors are effectively shaped so that they do not enter the second breakdown area, thereby preventing second breakdown destruction of the transistors

  8. Dynamics of voltage source converter in a grid connected solar photovoltaic system

    DEFF Research Database (Denmark)

    Haribabu, Divyanagalakshmi; Vangari, Adithya; Sakamuri, Jayachandra N.

    2015-01-01

    This paper emphasises the modelling and control of a voltage source converter (VSC) for three phase grid connected PV system. The transfer functions for inner current control and outer DC link voltage control for VSC are derived. The controllers for VSC are designed based on PI and K factor contr...

  9. An Integrated Inductor For Parallel Interleaved Three-Phase Voltage Source Converters

    DEFF Research Database (Denmark)

    Gohil, Ghanshyamsinh Vijaysinh; Bede, Lorand; Teodorescu, Remus

    2016-01-01

    Three phase Voltage Source Converters (VSCs) are often connected in parallel to realize high current output converter system. The harmonic quality of the resultant switched output voltage can be improved by interleaving the carrier signals of these parallel connected VSCs. As a result, the line...... of the state-of-the-art filtering solution. The performance of the integrated inductor is also verified by the experimental measurements....

  10. The sagging rope sign in achondroplasia - different from Perthes' disease

    International Nuclear Information System (INIS)

    Shingade, Viraj U.; Song, Hae-Ryong; Lee, Seok-Hyun; Suh, Seung-Woo; Oh, Chang-Wug; Hong, Jun-Seok

    2006-01-01

    The sagging rope sign is a radio-opaque line, seen on radiographs of the hips, with Perthes' disease. The main purpose of this study was to determine the incidence, cause and importance of this sign in achondroplasia, and to reveal how it differs from in Perthes' disease. Serial radiograms, along with 2-dimensional and 3-dimensional CT images were studied in 42 achondroplasic patients. Forty-two achondroplasic patients, reported at our institute (for routine outpatient consultation, spine surgeries, deformity corrections, limb-lengthening procedures) were included in this study. There were 26 males and 16 females. The sign was observed bilaterally, in all patients. Evaluation of CT images revealed spherical heads, with presence of circumferential overhang in all hips. This circumferential overhang, seen on 3-D CT scan, corresponded to the sagging rope sign on radiographs. Presence of the sagging rope sign in bilateral hips is a characteristic feature of achondroplasia. It usually appears before epiphyseal closure. Its cause, incidence, and nature differ from Perthes' disease, and its presence does not carry a bad prognosis in achondroplasia. (orig.)

  11. Synthesis, morphological control, and antibacterial properties of hollow/solid Ag2S/Ag heterodimers

    KAUST Repository

    Pang, Maolin; Hu, Jiangyong; Zeng, Huachun

    2010-01-01

    of this highly asymmetric dipolar composite, photocatalytic inactivation of Escherichia coli K-12 in the presence of the as-prepared Ag 2S/Ag heterodimers has been carried out under UV irradiation. The added Ag2S/Ag heterodimers show good chemical stability under

  12. Measurement and computation for sag of calandria tube due to irradiation creep in PHWR

    International Nuclear Information System (INIS)

    Son, S. M.; Lee, W. R.; Lee, S. K.; Lee, J. S.; Kim, T. R.; Na, B. K.; Namgung I.

    2003-01-01

    Calandria tubes and Liquid Injection Shutdown System(LISS) tubes in a Pressurized Heavy Water Reactor(PHWR) are to sag due to irradiation creep and growth during plant operation. When the sag of calandria tube becomes bigger, the calandria tube possibly comes in contact with LISS tube crossing beneath the calandria tube. The contact subsequently may cause the damage on the calandria tube resulting in unpredicted outage of the plant. It is therefore necessary to check the gap between the two tubes in order to periodically confirm no contact by using a proper measure during the plant life. An ultrasonic gap measuring probe assembly which can be inserted into two viewing ports of the calandria was developed in Korea and utilized to measure the sags of both tubes in the PHWR. It was found that the centerlines of calandria tubes and liquid injection shutdown system tubes can be precisely detected by ultrasonic wave. The gaps between two tubes were easily obtained from the relative distance of the measured centerline elevations of the tubes. Based on the irradiation creep equation and the measurement data, a computer program to calculate the sags was also developed. With the computer program, the sag at the end of plant life was predicted

  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. Multifunctional voltage source inverter for renewable energy integration and power quality conditioning.

    Science.gov (United States)

    Dai, NingYi; Lam, Chi-Seng; Zhang, WenChen

    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 fundamental frequency impedance of their coupling branch. The operation voltages of the two VSIs are compared when they are used for renewable energy integration and power quality conditioning simultaneously. The operation voltage of the capacitive-coupling VSI can be set much lower than that of the inductive-coupling VSI when reactive power is for compensating inductive loads. Since a large portion of the loads in the distribution system are inductive, the capacitive-coupling VSI is further studied. The design and control method of the multifunctional capacitive-coupling VSI are proposed in this paper. Simulation and experimental results are provided to show its validity.

  15. A control strategy based on UTT and I CosΘ theory of three-phase ...

    African Journals Online (AJOL)

    The performance of the implemented control algorithm is evaluated in terms of power-factor correction; load balancing, neutral source current mitigation and mitigation of voltage and current harmonics, voltage sag and swell and voltage dips in a three-phase four-wire distribution system for different combination of linear and ...

  16. Analytical modeling of Schottky tunneling source impact ionization MOSFET with reduced breakdown voltage

    Directory of Open Access Journals (Sweden)

    Sangeeta Singh

    2016-03-01

    Full Text Available In this paper, we have investigated a novel Schottky tunneling source impact ionization MOSFET (STS-IMOS to lower the breakdown voltage of conventional impact ionization MOS (IMOS and developed an analytical model for the same. In STS-IMOS there is an accumulative effect of both impact ionization and source induced barrier tunneling. The silicide source offers very low parasitic resistance, the outcome of which is an increment in voltage drop across the intrinsic region for the same applied bias. This reduces operating voltage and hence, it exhibits a significant reduction in both breakdown and threshold voltage. STS-IMOS shows high immunity against hot electron damage. As a result of this the device reliability increases magnificently. The analytical model for impact ionization current (Iii is developed based on the integration of ionization integral (M. Similarly, to get Schottky tunneling current (ITun expression, Wentzel–Kramers–Brillouin (WKB approximation is employed. Analytical models for threshold voltage and subthreshold slope is optimized against Schottky barrier height (ϕB variation. The expression for the drain current is computed as a function of gate-to-drain bias via integral expression. It is validated by comparing it with the technology computer-aided design (TCAD simulation results as well. In essence, this analytical framework provides the physical background for better understanding of STS-IMOS and its performance estimation.

  17. Biodegradation and detoxification of melanoidin from distillery effluent using an aerobic bacterial strain SAG{sub 5} of Alcaligenes faecalis

    Energy Technology Data Exchange (ETDEWEB)

    Santal, Anita Rani, E-mail: anita.gangotra@gmail.com [Department of Microbiology, Maharshi Dayanand University, Rohtak-124001, Haryana (India); Singh, N.P. [Centre for Biotechnology, Maharshi Dayanand University, Rohtak-124001, Haryana (India); Saharan, Baljeet Singh [Department of Microbiology, Kurukshetra University, Kurukshetra-136119, Haryana (India)

    2011-10-15

    Highlights: {yields} The Alcaligenes faecalis strain SAG{sub 5} decolorizes 72.6 {+-} 0.56% of melanoidins. {yields} The decolorization was achieved at pH 7.5 and temperature 37 {sup o}C on 5th day. {yields} The distillery effluent after biological treatment is environmentally safe. - Abstract: Distillery effluent retains very dark brown color even after anaerobic treatment due to presence of various water soluble, recalcitrant and coloring compounds mainly melanoidins. In laboratory conditions, melanoidin decolorizing bacteria was isolated and optimized the cultural conditions at various incubation temperatures, pH, carbon sources, nitrogen sources and combined effect of both carbon and nitrogen sources. The optimum decolorization (72.6 {+-} 0.56%) of melanoidins was achieved at pH 7.5 and temperature 37 {sup o}C on 5th day of cultivation. The toxicity evaluation with mung bean (Vigna radiata) revealed that the raw distillery effluent was environmentally highly toxic as compared to biologically treated distillery effluent, which indicated that the effluent after bacterial treatment is environmentally safe. This proves to be novel biological treatment technique for biodegradation and detoxification of melanoidin from distillery effluent using the bacterial strain SAG{sub 5}.

  18. Strains of Sarcocystis neurona exhibit differences in their surface antigens, including the absence of the major surface antigen SnSAG1.

    Science.gov (United States)

    Howe, Daniel K; Gaji, Rajshekhar Y; Marsh, Antoinette E; Patil, Bhagyashree A; Saville, William J; Lindsay, David S; Dubey, J P; Granstrom, David E

    2008-05-01

    A gene family of surface antigens is expressed by merozoites of Sarcocystis neurona, the primary cause of equine protozoal myeloencephalitis (EPM). These surface proteins, designated SnSAGs, are immunodominant and therefore excellent candidates for development of EPM diagnostics or vaccines. Prior work had identified an EPM isolate lacking the major surface antigen SnSAG1, thus suggesting there may be some diversity in the SnSAGs expressed by different S. neurona isolates. Therefore, a bioinformatic, molecular and immunological study was conducted to assess conservation of the SnSAGs. Examination of an expressed sequence tag (EST) database revealed several notable SnSAG polymorphisms. In particular, the EST information implied that the EPM strain SN4 lacked the major surface antigen SnSAG1. The absence of this surface antigen from the SN4 strain was confirmed by both Western blot and Southern blot. To evaluate SnSAG polymorphisms in the S. neurona population, 14 strains were examined by Western blots using monospecific polyclonal antibodies against the four described SnSAGs. The results of these analyses demonstrated that SnSAG2, SnSAG3, and SnSAG4 are present in all 14 S. neurona strains tested, although some variance in SnSAG4 was observed. Importantly, SnSAG1 was not detected in seven of the strains, which included isolates from four cases of EPM and a case of fatal meningoencephalitis in a sea otter. Genetic analyses by PCR using gene-specific primers confirmed the absence of the SnSAG1 locus in six of these seven strains. Collectively, the data indicated that there is heterogeneity in the surface antigen composition of different S. neurona isolates, which is an important consideration for development of serological tests and prospective vaccines for EPM. Furthermore, the diversity reported herein likely extends to other phenotypes, such as strain virulence, and may have implications for the phylogeny of the various Sarcocystis spp. that undergo sexual stages

  19. Analysis of Paralleling Limited Capacity Voltage Sources by Projective Geometry Method

    Directory of Open Access Journals (Sweden)

    Alexandr Penin

    2014-01-01

    Full Text Available The droop current-sharing method for voltage sources of a limited capacity is considered. Influence of equalizing resistors and load resistor is investigated on uniform distribution of relative values of currents when the actual loading corresponds to the capacity of a concrete source. Novel concepts for quantitative representation of operating regimes of sources are entered with use of projective geometry method.

  20. Mitigation of Flicker using STATCOM with Three-Level 12-pulse Voltage Source Inverter

    OpenAIRE

    Ali Z a'fari

    2011-01-01

    Voltage flicker is a disturbance in electrical power systems. The reason for this disturbance is mainly the large nonlinear loads such as electric arc furnaces. Synchronous static compensator (STATCOM) is considered as a proper technique to mitigate the voltage flicker. Application of more suitable and precise power electronic converter leads to a more precise performance of the compensator. In this paper a three-level 12-pulse voltage source inverter (VSI) with a 12-term...

  1. Cloning and characterisation of the sagA gene of Aspergillus nidulans: a gene which affects sensitivity to DNA-damaging agents.

    Science.gov (United States)

    Jones, G W; Hooley, P; Farrington, S M; Shawcross, S G; Iwanejko, L A; Strike, P

    1999-03-01

    Mutations within the sagA gene of Aspergillus nidulans cause sensitisation to DNA-damaging chemicals but have no effect upon spontaneous or damage-induced mutation frequency. The sagA gene was cloned on a 19-kb cosmid-derived fragment by functional complementation of a sagA1 sagC3 double mutant; subsequently, a fragment of the gene was also isolated on a 3.9-kb genomic subclone. Initial sequencing of a small section of the 19-kb fragment allowed the design of primers that were subsequently used in RTPCR experiments to show that this DNA is transcribed. A 277-bp fragment derived from the transcribed region was used to screen an A. nidulans cDNA library, resulting in the isolation of a 1.4-kb partial cDNA clone which had sequence overlap with the genomic sagA fragment. This partial cDNA was incomplete but appeared to contain the whole coding region of sagA. The sagA1 mutant was shown to possess two mutations; a G-T transversion and a+ 1 frameshift due to insertion of a T. causing disruption to the C-terminal region of the SagA protein. Translation of the sagA cDNA predicts a protein of 378 amino acids, which has homology to the Saccharomyces cerevisiae End3 protein and also to certain mammalian proteins capable of causing cell transformation.

  2. Selective Harmonic Virtual Impedance for Voltage Source Inverters with LCL filter in Microgrids

    DEFF Research Database (Denmark)

    Savaghebi, Mehdi; Vasquez, Juan Carlos; Jalilian, Alireza Jalilian

    2012-01-01

    This paper presents a new control approach for voltage source inverters ended with LCL filters for microgrid applications. The control approach consists of voltage and current inner control loops in order to fix the filter capacitor voltage and a virtual impedance loop. The virtual impedance...... is added in order to mitigate the voltage distortion after the output inductor and improve the load sharing among parallel inverters. A general case with a combined voltage harmonic and unbalance distortion is considered. In such a case, voltage distortion is mitigated by inserting capacitive virtual...... impedance for negative sequence of fundamental component as well as positive and negative sequences of main harmonic components. Furthermore, resistive virtual impedances are added at these components in order to provide a proper load sharing and make the overall system more damped. Simulation results...

  3. Fast Coordinated Control of DFIG Wind Turbine Generators for Low and High Voltage Ride-Through

    Directory of Open Access Journals (Sweden)

    Yun Wang

    2014-06-01

    Full Text Available This paper presents a fast coordinated control scheme of the rotor side converter (RSC, the Direct Current (DC chopper and the grid side converter (GSC of doubly fed induction generator (DFIG wind turbine generators (WTGs to improve the low voltage ride through (LVRT and high voltage ride through (HVRT capability of the DFIG WTGs. The characteristics of DFIG WTGs under voltage sags and swells were studied focusing on the DFIG WTG stator flux and rotor voltages during the transient periods of grid voltage changes. The protection schemes of the rotor crowbar circuit and the DC chopper circuit were proposed considering the characteristics of the DFIG WTGs during voltage changes. The fast coordinated control of RSC and GSC were developed based on the characteristic analysis in order to realize efficient LVRT and HVRT of the DFIG WTGs. The proposed fast coordinated control schemes were verified by time domain simulations using Matlab-Simulink.

  4. Crosstalk measurement on the D-III neutral beam power supplies

    International Nuclear Information System (INIS)

    Nerm, A.; Bowles, E.; Callis, R.W.; Colleraine, A.; Cowels, G.; Finizio, R.; Moore, D.; Tooker, J.F.; Varga, H.

    1983-01-01

    The Doublet III neutral beam plasma heating system comprises three beamlines with a total of six ion sources. Each of these ion sources is energized from a Neutral Beam Power System (NBPS) which is capable of delivering pulses at 80 kV and 100 A with pulse lengths up to 1 second in duration. A 138 kV San Diego Gas and Electric Company line is used as the prime power source for the NBPS. The 138 kV line is stepped down through an 84 MVA (pulse rating) 138 kV-12.47 kV transformer and an 8 MVA (pulse rating) 138 kV--480 V transformer. The 12.47 kV transformer feeds six NBPS high voltage circuits. The 480 V transformer supplies power to the filament, arc, and auxiliary power systems and control consoles in each NBPS. Each of the NBPS may block (controlled interruption of NBPS to protect the ion source) several times during a shot. Voltage variations due to such blocking by one or more systems have been measured on the 12.47 kV distribution bus as part of an effort to reduce system interaction. Interaction due to blocking during shots was found to be caused by noise picked up in low level circuits during ion source faults. High voltage DC fluctuations due to blocking do not cause interaction unless the voltage sags below the minimum required anode voltage for the pulse tetrodes in the Modular/Regulator, but interaction due to crowbar of the high voltage DC supply by a NBPS may result in a domino effect unless the remaining online systems are caused to block until the crowbarred system is cleared from the line (This feature is not presently implemented.). Voltage sag on the 480 V bus results from simultaneous operation of the ion sources. This sag, when it occurs, may lower the arc power input to the ion sources and cause reduced output power

  5. Synthesis, morphological control, and antibacterial properties of hollow/solid Ag2S/Ag heterodimers

    KAUST Repository

    Pang, Maolin

    2010-08-11

    Ag2S and Ag are important functional materials that have received considerable research interest in recent years. In this work, we develop a solution-based synthetic method to combine these two materials into hollow/solid Ag2S/Ag heterodimers at room temperature. Starting from monodisperse Cu2O solid spheres, CuS hollow spheres can be converted from Cu2O through a modified Kirkendall process, and the obtained CuS can then be used as a solid precursor for preparation of the Ag2S/Ag heterodimers through ion exchange and photo-assisted reduction. We have found that formation of the Ag2S/Ag heterodimers is instantaneous, and the size of Ag nanocrystals on the hollow spheres of Ag2S can be controlled by changing the concentration and power of reducing agents in the synthesis. The growth of Ag nanoparticles on hollow spheres of Ag2S in the dimers is along the [111] direction of the silver crystal; the light absorption properties have also been investigated. Furthermore, coupling or tripling of Ag2S/Ag heterodimers into dumbbell-like trimers ((Ag 2S)2/Ag, linear) and triangular tetramers ((Ag 2S)3/Ag, coplanar) can also be attained at 60°C by adding the bidentate ligand ethylenediamine as a cross-linking agent. To test the applicability of this highly asymmetric dipolar composite, photocatalytic inactivation of Escherichia coli K-12 in the presence of the as-prepared Ag 2S/Ag heterodimers has been carried out under UV irradiation. The added Ag2S/Ag heterodimers show good chemical stability under prolonged UV irradiation, and no appreciable solid dissolution is found. Possible mechanisms regarding the enhanced antibacterial activity have also been addressed. © 2010 American Chemical Society.

  6. Experimental testing of a SAG digital SILT application

    International Nuclear Information System (INIS)

    Haapanen, P.; Maskuniitty, M.; Heikkinen, J.; Korhonen, J.

    1995-10-01

    A prototype dynamic testing harness for programmable automation systems has been specified and implemented at the Technical Research Centre of Finland (VTT). In order to get experience on the methodology and equipment for the testing of systems important to the safety of nuclear power plants, where the safety and reliability requirements often are very high, two different pilot systems have been tested. One system was an ABB Master application, which was loaned for testing from ABB Atom by Teollisuuden Voima Oy (TVO). Another system, loaned from Siemens AG(SAG) by IVO International Oy (IVO), was an application realized with SAG's digital SILT technology. The report describes the testing of the SAG application. The purpose of the testing was not to assess the pilot system, but to get experience in the testing methodology and find out the further development needs and potentials of the test methodology and equipment. The experience show that dynamic testing is one feasible way to get more confidence about the safety and reliability of a programmable system that would be hard to achieve by other means. It also shows that more development of the test harness is still needed, especially concerning the comparison of the obtained test response to the expected response provided by the logical model of the system. Also the user interface of the on-line part of the test harness needs development. Methods for generation of the test cases also need further development eg. for achieving statistical significance for the reliability estimates. (10 refs., 90 figs., 9 tabs.)

  7. The sagging rope sign in achondroplasia - different from Perthes' disease

    Energy Technology Data Exchange (ETDEWEB)

    Shingade, Viraj U. [Korea University, Department of Paediatric Orthopaedics, College of Medicine, Guro Hospital, Seoul (Korea); Song, Hae-Ryong [Korea University, Department of Paediatric Orthopaedic Surgery, College of Medicine, Guro Hospital, Seoul (Korea); Lee, Seok-Hyun; Suh, Seung-Woo [Korea University, Department of Orthopaedic Surgery, College of Medicine, Guro Hospital, Seoul (Korea); Oh, Chang-Wug [Kyungpook National University Hospital, Department of Orthopaedic Surgery, Daegu (Korea); Hong, Jun-Seok [Ansan Hospital, Department of Orthopaedic Surgery, Korea University, Ansan, Gyeonggi do (Korea)

    2006-12-15

    The sagging rope sign is a radio-opaque line, seen on radiographs of the hips, with Perthes' disease. The main purpose of this study was to determine the incidence, cause and importance of this sign in achondroplasia, and to reveal how it differs from in Perthes' disease. Serial radiograms, along with 2-dimensional and 3-dimensional CT images were studied in 42 achondroplasic patients. Forty-two achondroplasic patients, reported at our institute (for routine outpatient consultation, spine surgeries, deformity corrections, limb-lengthening procedures) were included in this study. There were 26 males and 16 females. The sign was observed bilaterally, in all patients. Evaluation of CT images revealed spherical heads, with presence of circumferential overhang in all hips. This circumferential overhang, seen on 3-D CT scan, corresponded to the sagging rope sign on radiographs. Presence of the sagging rope sign in bilateral hips is a characteristic feature of achondroplasia. It usually appears before epiphyseal closure. Its cause, incidence, and nature differ from Perthes' disease, and its presence does not carry a bad prognosis in achondroplasia. (orig.)

  8. Phase-lock loop of Grid-connected Voltage Source Converter under non-ideal grid condition

    DEFF Research Database (Denmark)

    Wang, Haojie; Sun, Hai; Han, Minxiao

    2015-01-01

    It is a normal practice that the DC micro-grid is connected to AC main grid through Grid-connected Voltage Source Converter (G-VSC) for voltage support. Accurate control of DC micro-grid voltage is difficult for G-VSC under unbalanced grid condition as the fundamental positive-sequence component...... and distorted system voltage the proposed PLL can accurately detect the fundamental positive-sequence component of grid voltage thus accurate control of DC micro-grid voltage can be realized....... phase information cannot be accurately tracked. Based on analysis of the cause of double-frequency ripple when unbalance exists in main grid, a phase-locked loop (PLL) detection technique is proposed. Under the conditions of unsymmetrical system voltage, varying system frequency, single-phase system...

  9. A digital controlled negative high voltage power source for LINAC of HLS

    International Nuclear Information System (INIS)

    Gao Hui; Chen Jun; Hong Jun; Wang Weibing

    2005-01-01

    This paper introduces the working principle of a 10-80 kV negative high voltage power source for the electronic gun of the 200 MeV LINAC of NSRL, especially how to realize the switch power, voltage/current sampling, feedback control and microcontroller module. The firmware design for the SOC microcontroller of ADuC8xx and the application software design for PC are also presented. (authors)

  10. Active control of flying capacitor currents in multilevel voltage-source inverters

    Czech Academy of Sciences Publication Activity Database

    Kokeš, Petr; Semerád, Radko

    2013-01-01

    Roč. 58, č. 4 (2013), s. 393-410 ISSN 0001-7043 Institutional support: RVO:61388998 Keywords : voltage source inverter (VSI) * multilevel inverter * flying capacitor Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  11. Physical simulation of gas reservoir formation in the Liwan 3-1 deep-water gas field in the Baiyun sag, Pearl River Mouth Basin

    Directory of Open Access Journals (Sweden)

    Gang Gao

    2015-01-01

    Full Text Available To figure out the process and controlling factors of gas reservoir formation in deep-waters, based on an analysis of geological features, source of natural gas and process of reservoir formation in the Liwan 3-1 gas field, physical simulation experiment of the gas reservoir formation process has been performed, consequently, pattern and features of gas reservoir formation in the Baiyun sag has been found out. The results of the experiment show that: ① the formation of the Liwan 3-1 faulted anticline gas field is closely related to the longstanding active large faults, where natural gas is composed of a high proportion of hydrocarbons, a small amount of non-hydrocarbons, and the wet gas generated during highly mature stage shows obvious vertical migration signs; ② liquid hydrocarbons associated with natural gas there are derived from source rock of the Enping & Zhuhai Formation, whereas natural gas comes mainly from source rock of the Enping Formation, and source rock of the Wenchang Formation made a little contribution during the early Eocene period as well; ③ although there was gas migration and accumulation, yet most of the natural gas mainly scattered and dispersed due to the stronger activity of faults in the early period; later as fault activity gradually weakened, gas started to accumulate into reservoirs in the Baiyun sag; ④ there is stronger vertical migration of oil and gas than lateral migration, and the places where fault links effective source rocks with reservoirs are most likely for gas accumulation; ⑤ effective temporal-spatial coupling of source-fault-reservoir in late stage is the key to gas reservoir formation in the Baiyun sag; ⑥ the nearer the distance from a trap to a large-scale fault and hydrocarbon source kitchen, the more likely gas may accumulate in the trap in late stage, therefore gas accumulation efficiency is much lower for the traps which are far away from large-scale faults and hydrocarbon source

  12. Effect of state feedback coupling on the transient performance of voltage source inverters with LC filter

    DEFF Research Database (Denmark)

    Federico, de Bosio; Pastorelli, Michele; Antonio DeSouza Ribeiro, Luiz

    2016-01-01

    State feedback coupling between the capacitor voltage and inductor current deteriorates notably the performance during transients of voltage and current regulators in stand-alone systems based on voltage source inverters. A decoupling technique is proposed, considering the limitations introduced...

  13. Gravity sag view of lateral radiography of the knee

    International Nuclear Information System (INIS)

    Hidaka, Kuniyuki; Yanagawa, Yasuhiro; Kawamoto, Kiyosumi; Maeda, Daisuke; Komizu, Mitsuru

    2007-01-01

    The gravity sag view (GSV) is a lateral radiograph taken in the same position when the posterior sag sign is observed. The purpose of this study was to standardize the radiography technique for GSV by adjusting lateral rotation. To confirm the benchmark and correction angle (CA) for the GSV position, we assessed three-dimensional (3D) CT of the GSV position of the knee using normal volunteers. The benchmark is established at the 3-point of the leg and adjusting the CA of the knee is established by estimating from Rosenberg technique radiography. This helped not only to correct external rotation in the initial radiography but also to correct rotation for repeat radiography. Our method is quantitative and highly reproducible, and it increases the success rate in adjusting lateral radiography of the knee. (author)

  14. The role of fluid migration system in hydrocarbon accumulation in Maichen Sag, Beibuwan Basin

    Science.gov (United States)

    Liu, Hongyu; Yang, Jinxiu; Wu, Feng; Chen, Wei; Liu, Qianqian

    2018-02-01

    Fluid migration system is of great significance for hydrocarbon accumulation, including the primary migration and secondary migration. In this paper, the fluid migration system is analysed in Maichen Sag using seismic, well logging and core data. Results show that many factors control the hydrocarbon migration process, including hydrocarbon generation and expulsion period from source rocks, microfractures developed in the source rocks, the connected permeable sand bodies, the vertical faults cutting into/through the source rocks and related fault activity period. The spatial and temporal combination of these factors formed an effective network for hydrocarbon expulsion and accumulation, leading to the hydrocarbon reservoir distribution at present. Generally, a better understanding of the hydrocarbon migration system can explain the present status of hydrocarbon distribution, and help select future target zones for oil and gas exploration.

  15. Facile synthesis, structure, and properties of Ag{sub 2}S/Ag heteronanostructure

    Energy Technology Data Exchange (ETDEWEB)

    Sadovnikov, S. I., E-mail: sadovnikov@ihim.uran.ru; Gusev, A. I. [Ural Branch of the Russian Academy of Sciences, Institute of Solid State Chemistry (Russian Federation)

    2016-09-15

    Ag{sub 2}S/Ag heteronanostructure has been produced by a simple one-stage chemical deposition from aqueous solutions of silver nitrate, sodium sulfide, and sodium citrate with the use of monochromatic light irradiation. For simultaneous synthesis of Ag{sub 2}S and Ag nanoparticles, deposition has been performed from reaction mixtures with reduced sodium sulfide concentration. The size of Ag{sub 2}S and Ag nanoparticles is 45–50 and 15–20 nm, respectively. It is established that in the contact layer between silver sulfide and silver, nonconducting α-Ag{sub 2}S acanthite transforms into superionic β-Ag{sub 2}S argentite under the action of external electric field. The scheme of the operation of a resistive switch based on an Ag{sub 2}S/Ag heteronanostructure is proposed. The UV–Vis optical absorption spectra of colloidal solutions of Ag{sub 2}S/Ag heteronanostructures have been studied.Graphical Abstract.

  16. Charge-pump voltage converter

    Science.gov (United States)

    Brainard, John P [Albuquerque, NM; Christenson, Todd R [Albuquerque, NM

    2009-11-03

    A charge-pump voltage converter for converting a low voltage provided by a low-voltage source to a higher voltage. Charge is inductively generated on a transfer rotor electrode during its transit past an inductor stator electrode and subsequently transferred by the rotating rotor to a collector stator electrode for storage or use. Repetition of the charge transfer process leads to a build-up of voltage on a charge-receiving device. Connection of multiple charge-pump voltage converters in series can generate higher voltages, and connection of multiple charge-pump voltage converters in parallel can generate higher currents. Microelectromechanical (MEMS) embodiments of this invention provide a small and compact high-voltage (several hundred V) voltage source starting with a few-V initial voltage source. The microscale size of many embodiments of this invention make it ideally suited for MEMS- and other micro-applications where integration of the voltage or charge source in a small package is highly desirable.

  17. Harmonic Analysis and Mitigation of Low- Frequency Switching Voltage Source Inverter with Auxiliary VSI

    DEFF Research Database (Denmark)

    Bai, Haofeng; Wang, Xiongfei; Blaabjerg, Frede

    2018-01-01

    The output currents of high-power Voltage Source Inverters (VSIs) are distorted by the switching harmonics and the background harmonics in the grid voltage. This paper presents an active harmonic filtering scheme for high-power, low-frequency switching VSIs with an additional auxiliary VSI. In th...

  18. Control of grid integrated voltage source converters under unbalanced conditions: development of an on-line frequency-adaptive virtual flux-based approach

    Energy Technology Data Exchange (ETDEWEB)

    Suul, Jon Are

    2012-03-15

    Three-Phase Voltage Source Converters (VSCs) are finding widespread applications in grid integrated power conversion systems. The control systems of such VSCs are in an increasing number of these applications required to operate during voltage disturbances and unbalanced conditions. Control systems designed for grid side voltagesensor-less operation are at the same time becoming attractive due to the continuous drive for cost reduction and increased reliability of VSCs, but are not commonly applied for operation during unbalanced conditions. Methods for voltage-sensor-less grid synchronization and control of VSCs under unbalanced grid voltage conditions will therefore be the main focus of this Thesis. Estimation methods based on the concept of Virtual Flux, considering the integral of the converter voltage in analogy to the flux of an electric machine, are among the simplest and most well known techniques for achieving voltage-sensor-less grid synchronization. Most of the established techniques for Virtual Flux estimation are, however, either sensitive to grid frequency variations or they are not easily adaptable for operation under unbalanced grid voltage conditions. This Thesis addresses both these issues by proposing a simple approach for Virtual Flux estimation by utilizing a frequency-adaptive filter based on a Second Order Generalized Integrator (SOGI). The proposed approach can be used to achieve on-line frequency-adaptive varieties of conventional strategies for Virtual Flux estimation. The main advantage is, however, that the SOGI-based Virtual Flux estimation can be arranged in a structure that achieves inherent symmetrical component sequence separation under unbalanced conditions. The proposed method for Virtual Flux estimation can be used as a general basis for voltage-sensor-less grid synchronization and control during unbalanced conditions. In this Thesis, the estimated Virtual Flux signals are used to develop a flexible strategy for control of active

  19. Discrete-Time Domain Modelling of Voltage Source Inverters in Standalone Applications

    DEFF Research Database (Denmark)

    Federico, de Bosio; de Sousa Ribeiro, Luiz Antonio; Freijedo Fernandez, Francisco Daniel

    2017-01-01

    modelling of the LC plant with consideration of delay and sample-and-hold effects on the state feedback cross-coupling decoupling is derived. From this plant formulation, current controllers with wide bandwidth and good relative stability properties are developed. Two controllers based on lead compensation......The decoupling of the capacitor voltage and inductor current has been shown to improve significantly the dynamic performance of voltage source inverters in standalone applications. However, the computation and PWM delays still limit the achievable bandwidth. In this paper a discrete-time domain...

  20. Low-Voltage Ride-Through Operation of Power Converters in Grid-Interactive Microgrids by Using Negative-Sequence Droop Control

    DEFF Research Database (Denmark)

    Zhao, Xin; Guerrero, Josep M.; Savaghebi, Mehdi

    2017-01-01

    of the utility grid during grid faults. In this paper, a LVRT control strategy based on positive/negative sequence droop control is proposed for grid-interactive MGs to ride-through voltage sags with not only inductive/resistive, but also complex line impedance. By using the proposed control strategy, MGs can......Due to the increasing penetration level of microgrids (MGs), it becomes a critical issue for MGs to help sustaining power system stability. Therefore, ancillary services, such as the low-voltage ride-through (LVRT) capability should be incorporated in MGs in order to guarantee stable operation...... support the grid voltage, make profits, and also ride-through the voltage dip during the whole fault period. A two layer hierarchical control strategy is proposed in this paper. The primary controller consists of voltage and current inner loops, a conventional droop control and a virtual impedance loop...

  1. Challenges to Grid Synchronization of Single-Phase Grid-Connected Inverters in Zero-Voltage Ride-Through Operation

    DEFF Research Database (Denmark)

    Zhang, Zhen; Yang, Yongheng; Blaabjerg, Frede

    2016-01-01

    With the fast development in Photovoltaic (PV) technology, the relevant grid-connection requirements/standards are continuously being updated, and more challenges have been imposed on both single-phase and three-phase grid-connected PV systems. For instance, PV systems are currently required...... to remain connected under grid voltage sags (even zero voltage condition). In this case, much attention should be paid to the grid synchronization in such a way to properly ride-through grid faults. Thus, in this paper, the most commonly-used and recently-developed Phase Locked Loop (PLL) synchronization...... methods have been evaluated for single-phase grid-connected PV systems in the case of Zero-Voltage Ride-Through (ZVRT) operation. The performances of the prior-art PLL methods in response to zero voltage faults in terms of detection precision and dynamic response are assessed in this paper. Simulation...

  2. Design and construction of constant voltage and current regulated source with proper characteristics to be used in electronics laboratory designs

    International Nuclear Information System (INIS)

    Peon A, R.

    1978-01-01

    A regulated direct current feeding source was designed for the Nuclear Energy National Institute Electronics Labortory, with the following characteristics: a) voltage input 105-130V a.c. 50-60 Hz; b) voltage output 0.40 V d.c.; c) output current 0-2 Amp d.c.; d) load regulation 0.001%; e) line regulation 0.001%; f) ripple and noise 200 μ Vpp; g) temperature interval 3-60 0 C; h) stability 0.5%; i) output impedance as voltage source 0.01 ohms; j) transient response 50 μ seg. Besides of operating normally, that is as voltage source or current-source through the front controls, the source can be used and interconnected with one or other compatible sources (autoseries, autoparallel and programmed reference). The source will cost 70,000 pesos approximately. (author)

  3. Screening and identification of novel B cell epitopes of Toxoplasma gondii SAG1

    OpenAIRE

    Wang, Yanhua; Wang, Guangxiang; Zhang, Delin; Yin, Hong; Wang, Meng

    2013-01-01

    Background The identification of protein epitopes is useful for diagnostic purposes and for the development of peptide vaccines. In this study, the epitopes of Toxoplasma gondii SAG1 were identified using synthetic peptide techniques with the aid of bioinformatics. Findings Eleven peptides derived from T. gondii SAG1 were assessed by ELISA using pig sera from different time points after infection. Four (PS4, PS6, PS10 and PS11), out of the eleven peptides tested were recognized by all sera. T...

  4. Low-Cost Open-Source Voltage and Current Monitor for Gas Metal Arc Weld 3D Printing

    Directory of Open Access Journals (Sweden)

    A. Pinar

    2015-01-01

    Full Text Available Arduino open-source microcontrollers are well known in sensor applications for scientific equipment and for controlling RepRap 3D printers. Recently low-cost open-source gas metal arc weld (GMAW RepRap 3D printers have been developed. The entry-level welders used have minimal controls and therefore lack any real-time measurement of welder voltage or current. The preliminary work on process optimization of GMAW 3D printers requires a low-cost sensor and data logger system to measure welder current and voltage. This paper reports on the development of a low-cost open-source power measurement sensor system based on Arduino architecture. The sensor system was designed, built, and tested with two entry-level MIG welders. The full bill of materials and open source designs are provided. Voltage and current were measured while making stepwise adjustments to the manual voltage setting on the welder. Three conditions were tested while welding with steel and aluminum wire on steel substrates to assess the role of electrode material, shield gas, and welding velocity. The results showed that the open source sensor circuit performed as designed and could be constructed for <$100 in components representing a significant potential value through lateral scaling and replication in the 3D printing community.

  5. Screening and identification of novel B cell epitopes of Toxoplasma gondii SAG1.

    Science.gov (United States)

    Wang, Yanhua; Wang, Guangxiang; Zhang, Delin; Yin, Hong; Wang, Meng

    2013-04-30

    The identification of protein epitopes is useful for diagnostic purposes and for the development of peptide vaccines. In this study, the epitopes of Toxoplasma gondii SAG1 were identified using synthetic peptide techniques with the aid of bioinformatics. Eleven peptides derived from T. gondii SAG1 were assessed by ELISA using pig sera from different time points after infection. Four (PS4, PS6, PS10 and PS11), out of the eleven peptides tested were recognized by all sera. Then, shorter peptides that were derived from PS4, PS6, PS10 and PS11 were predicted using bioinformatics and tested by experimentation. Four out of nine shorter peptides were identified successfully (amino acids 106-120, 166-180, 289-300 and 313-332). We have precisely located the epitopes of T. gondii SAG1 using pig sera collected at different time points after infection. The identified epitopes may be useful for the further study of epitope-based vaccines and diagnostic reagents.

  6. Adaptive Sliding Mode Control of MEMS AC Voltage Reference Source

    Directory of Open Access Journals (Sweden)

    Ehsan Ranjbar

    2017-01-01

    Full Text Available The accuracy of physical parameters of a tunable MEMS capacitor, as the major part of MEMS AC voltage reference, is of great importance to achieve an accurate output voltage free of the malfunctioning noise and disturbance. Even though strenuous endeavors are made to fabricate MEMS tunable capacitors with desiderated accurate physical characteristics and ameliorate exactness of physical parameters’ values, parametric uncertainties ineluctably emerge in fabrication process attributable to imperfections in micromachining process. First off, this paper considers applying an adaptive sliding mode controller design in the MEMS AC voltage reference source so that it is capable of giving off a well-regulated output voltage in defiance of jumbling parametric uncertainties in the plant dynamics and also aggravating external disturbance imposed on the system. Secondly, it puts an investigatory comparison with the designed model reference adaptive controller and the pole-placement state feedback one into one’s prospective. Not only does the tuned adaptive sliding mode controller show remarkable robustness against slow parameter variation and external disturbance being compared to the pole-placement state feedback one, but also it immensely gets robust against the external disturbance in comparison with the conventional adaptive controller. The simulation results are promising.

  7. Fixed speed wind farm operation improvement using current-source converter based UPQC

    International Nuclear Information System (INIS)

    Ajami, Ali; Armaghan, Mehdi

    2012-01-01

    Highlights: ► Reactive power and voltage sag are compensated during grid side fault. ► Nonlinear model of UPQC is modified to a linear model. ► Using the CSI in proposed UPQC offers a number of distinct advantages. ► Pitch angle controller is used to obtain nominal power at high wind speeds. ► Optimal control method (LQR) is used to determine the optimal state feedback gains. - Abstract: In this paper, a current-source converter based unified power quality conditioner (UPQC) is used for the flexible integration of pitch controlled fixed speed wind generator (FSWG) to IEEE 13 node test feeder. During the normal operation, shunt compensator (SHUC) of the UPQC maintains a unity power factor condition at the Point of Common Coupling (PCC) and when a voltage sag occurs due to grid side fault the series compensator (SERC) of the UPQC injects appropriate deficit voltage to prevent disconnecting of the FSWG and the SHUC of the UPQC provides additional reactive power in fault during. The pitch angle is controlled in order to limit the generator output power to its nominal value for high wind speeds. The nonlinear model of the shunt compensator of the UPQC is modified to a linear model. The modeling technique is not based on the linearization of a set of nonlinear equations around an operating point. Instead, the power balance equation and a nonlinear input transformation are used to derive a linear model independent of the operating point. This model acts as the basis for the design of a decoupled state-feedback controller. The optimal control method linear quadratic regulator (LQR) is used to determine the optimal state-feedback gain matrix. The proposed control approach becomes a robust strategy that is able to keep regulation and stability even under extreme load power factor variations. The In-phase voltage injection method is used for the series compensator of the UPQC. The simulation results carried out by MATLAB/SIMULINK software show the performance of the

  8. Effects of detector–source distance and detector bias voltage variations on time resolution of general purpose plastic scintillation detectors

    International Nuclear Information System (INIS)

    Ermis, E.E.; Celiktas, C.

    2012-01-01

    Effects of source-detector distance and the detector bias voltage variations on time resolution of a general purpose plastic scintillation detector such as BC400 were investigated. 133 Ba and 207 Bi calibration sources with and without collimator were used in the present work. Optimum source-detector distance and bias voltage values were determined for the best time resolution by using leading edge timing method. Effect of the collimator usage on time resolution was also investigated. - Highlights: ► Effect of the source-detector distance on time spectra was investigated. ► Effect of the detector bias voltage variations on time spectra was examined. ► Optimum detector–source distance was determined for the best time resolution. ► Optimum detector bias voltage was determined for the best time resolution. ► 133 Ba and 207 Bi radioisotopes were used.

  9. Accurate antemortem diagnosis of equine protozoal myeloencephalitis (EPM) based on detecting intrathecal antibodies against Sarcocystis neurona using the SnSAG2 and SnSAG4/3 ELISAs.

    Science.gov (United States)

    Reed, S M; Howe, D K; Morrow, J K; Graves, A; Yeargan, M R; Johnson, A L; MacKay, R J; Furr, M; Saville, W J A; Williams, N M

    2013-01-01

    Recent work demonstrated the value of antigen-specific antibody indices (AI and C-value) to detect intrathecal antibody production against Sarcocystis neurona for antemortem diagnosis of equine protozoal myeloencephalitis (EPM). The study was conducted to assess whether the antigen-specific antibody indices can be reduced to a simple serum : cerebrospinal fluid (CSF) titer ratio to achieve accurate EPM diagnosis. Paired serum and CSF samples from 128 horses diagnosed by postmortem examination. The sample set included 44 EPM cases, 35 cervical-vertebral malformation (CVM) cases, 39 neurologic cases other than EPM or CVM, and 10 non-neurologic cases. Antibodies against S. neurona were measured in serum and CSF pairs using the SnSAG2 and SnSAG4/3 (SnSAG2, 4/3) ELISAs, and the ratio of each respective serum titer to CSF titer was determined. Likelihood ratios and diagnostic sensitivity and specificity were calculated based on serum titers, CSF titers, and serum : CSF titer ratios. Excellent diagnostic sensitivity and specificity was obtained from the SnSAG2, 4/3 serum : CSF titer ratio. Sensitivity and specificity of 93.2 and 81.1%, respectively, were achieved using a ratio cutoff of ≤100, whereas sensitivity and specificity were 86.4 and 95.9%, respectively, if a more rigorous cutoff of ≤50 was used. Antibody titers in CSF also provided good diagnostic accuracy. Serum antibody titers alone yielded much lower sensitivity and specificity. The study confirms the value of detecting intrathecal antibody production for antemortem diagnosis of EPM, and they further show that the antigen-specific antibody indices can be reduced in practice to a simple serum : CSF titer ratio. Copyright © 2013 by the American College of Veterinary Internal Medicine.

  10. Recombinant vaccines against T. gondii: comparison between homologous and heterologous vaccination protocols using two viral vectors expressing SAG1.

    Science.gov (United States)

    Mendes, Érica Araújo; Fonseca, Flavio G; Casério, Bárbara M; Colina, Janaína P; Gazzinelli, Ricardo Tostes; Caetano, Braulia C

    2013-01-01

    The use of recombinant viral vectors expressing T. gondii antigens is a safe and efficient approach to induce immune response against the parasite and a valuable tool for vaccine development. We have previously protected mice from toxoplasmosis by immunizing the animals with an adenovirus expressing the protein SAG1 (AdSAG1) of T. gondii. We are now looking for ways to improve the vaccination strategy and enhance protection. One limitation of homologous vaccinations (sequential doses of the same vector) is induction of anti-vector immune response that blocks cell transduction, restricts transgene expression and, consequently, compromises the overall outcome of vaccination. One way to avert the effects of anti-vector response is to use different viruses in prime and boost (heterologous vaccination). Bearing this in mind, we generated a modified Vaccinia Virus Ankara encoding SAG1 (MVASAG1), to be tested as boost agent after prime with AdSAG1. Although minor differences were observed in the magnitude of the anti-SAG1 immune response induced by each vaccination protocol, the heterologous immunization with AdSAG1 followed by MVASAG1 resulted in improved capacity to control brain cyst formation in a model of chronic toxoplasmosis in C57BL/6 mice.

  11. Recombinant vaccines against T. gondii: comparison between homologous and heterologous vaccination protocols using two viral vectors expressing SAG1.

    Directory of Open Access Journals (Sweden)

    Érica Araújo Mendes

    Full Text Available The use of recombinant viral vectors expressing T. gondii antigens is a safe and efficient approach to induce immune response against the parasite and a valuable tool for vaccine development. We have previously protected mice from toxoplasmosis by immunizing the animals with an adenovirus expressing the protein SAG1 (AdSAG1 of T. gondii. We are now looking for ways to improve the vaccination strategy and enhance protection. One limitation of homologous vaccinations (sequential doses of the same vector is induction of anti-vector immune response that blocks cell transduction, restricts transgene expression and, consequently, compromises the overall outcome of vaccination. One way to avert the effects of anti-vector response is to use different viruses in prime and boost (heterologous vaccination. Bearing this in mind, we generated a modified Vaccinia Virus Ankara encoding SAG1 (MVASAG1, to be tested as boost agent after prime with AdSAG1. Although minor differences were observed in the magnitude of the anti-SAG1 immune response induced by each vaccination protocol, the heterologous immunization with AdSAG1 followed by MVASAG1 resulted in improved capacity to control brain cyst formation in a model of chronic toxoplasmosis in C57BL/6 mice.

  12. Modeling, analysis, and design of stationary reference frame droop controlled parallel three-phase voltage source inverters

    DEFF Research Database (Denmark)

    Vasquez, Juan Carlos; Guerrero, Josep M.; Savaghebi, Mehdi

    2013-01-01

    Power electronics based MicroGrids consist of a number of voltage source inverters (VSIs) operating in parallel. In this paper, the modeling, control design, and stability analysis of parallel connected three-phase VSIs are derived. The proposed voltage and current inner control loops and the mat......Power electronics based MicroGrids consist of a number of voltage source inverters (VSIs) operating in parallel. In this paper, the modeling, control design, and stability analysis of parallel connected three-phase VSIs are derived. The proposed voltage and current inner control loops...... control restores the frequency and amplitude deviations produced by the primary control. Also, a synchronization algorithm is presented in order to connect the MicroGrid to the grid. Experimental results are provided to validate the performance and robustness of the parallel VSI system control...

  13. Molecular analysis of Toxoplasma gondii Surface Antigen 1 (SAG1) gene cloned from Toxoplasma gondii DNA isolated from Javanese acute toxoplasmosis

    Science.gov (United States)

    Haryati, Sri; Agung Prasetyo, Afiono; Sari, Yulia; Dharmawan, Ruben

    2018-05-01

    Toxoplasma gondii Surface Antigen 1 (SAG1) is often used as a diagnostic tool due to its immunodominant-specific as antigen. However, data of the Toxoplasma gondii SAG1 protein from Indonesian isolate is limited. To study the protein, genomic DNA was isolated from a Javanese acute toxoplasmosis blood samples patient. A complete coding sequence of Toxoplasma gondii SAG1 was cloned and inserted into an Escherichia coli expression plasmid and sequenced. The sequencing results were subjected to bioinformatics analysis. The Toxoplasma gondii SAG1 complete coding sequences were successfully cloned. Physicochemical analysis revealed the 336 aa of SAG1 had 34.7 kDa of weight. The isoelectric point and aliphatic index were 8.4 and 78.4, respectively. The N-terminal methionine half-life in Escherichia coli was more than 10 hours. The antigenicity, secondary structure, and identification of the HLA binding motifs also had been discussed. The results of this study would contribute information about Toxoplasma gondii SAG1 and benefits for further works willing to develop diagnostic and therapeutic strategies against the parasite.

  14. Source-Drain Punch-Through Analysis of High Voltage Off-State AlGaN/GaN HEMT Breakdown

    Science.gov (United States)

    Jiang, H.; Li, X.; Wang, J.; Zhu, L.; Wang, H.; Liu, J.; Wang, M.; Yu, M.; Wu, W.; Zhou, Y.; Dai, G.

    2017-06-01

    AlGaN/GaN high-electron mobility transistor’s (HEMT’s) off-state breakdown is investigated using conventional three-terminal off-state breakdown I-V measurement. Competition between gate leakage and source-injection buffer leakage (SIBL) is discussed in detail. It is found that the breakdown is dominated by source-injection which is sensitive to gate voltage and gate length at large gate-to-drain spacing (Lgd > 7μm), where a threshold drain voltage of the occurrence of the SIBL current in GaN buffer exists, and after this threshold voltage the SIBL current continually increased till the buffer breakdown. Our analysis showed that due to the punch-through effect in the buffer, a potential barrier between 2DEG and GaN buffer at the source side mainly controlled by the drain voltage determines the buffer leakage current and the occurrence of the following buffer breakdown, which could explain the experimentally observed breakdown phenomenon.

  15. Comparison of three-phase three-level voltage source inverter with intermediate dc–dc boost converter and quasi-Z-source inverter

    DEFF Research Database (Denmark)

    Panfilov, Dmitry; Husev, Oleksandr; Blaabjerg, Frede

    2016-01-01

    This study compares a three-phase three-level voltage source inverter with an intermediate dc-dc boost converter and a quasi-Z-source inverter in terms of passive elements values and dimensions, semiconductor stresses, and overall efficiency. A comparative analysis was conducted with relative...

  16. New approaches to provide ride-through for critical loads in electric power distribution systems

    Science.gov (United States)

    Montero-Hernandez, Oscar C.

    2001-07-01

    The extensive use of electronic circuits has enabled modernization, automation, miniaturization, high quality, low cost, and other achievements regarding electric loads in the last decades. However, modern electronic circuits and systems are extremely sensitive to disturbances from the electric power supply. In fact, the rate at which these disturbances happen is considerable as has been documented in recent years. In response to the power quality concerns presented previously, this dissertation is proposing new approaches to provide ride-through for critical loads during voltage disturbances with emphasis on voltage sags. In this dissertation, a new approach based on an AC-DC-AC system is proposed to provide ride-through for critical loads connected in buildings and/or an industrial system. In this approach, a three-phase IGBT inverter with a built in Dc-link voltage regulator is suitably controlled along with static by-pass switches to provide continuous power to critical loads. During a disturbance, the input utility source is disconnected and the power from the inverter is connected to the load. The remaining voltage in the AC supply is converted to DC and compensated before being applied to the inverter and the load. After detecting normal utility conditions, power from the utility is restored to the critical load. In order to achieve an extended ride-through capability a second approach is introduced. In this case, the Dc-link voltage regulator is performed by a DC-DC Buck-Boost converter. This new approach has the capability to mitigate voltage variations below and above the nominal value. In the third approach presented in this dissertation, a three-phase AC to AC boost converter is investigated. This converter provides a boosting action for the utility input voltages, right before they are applied to the load. The proposed Pulse Width Modulation (PWM) control strategy ensures independent control of each phase and compensates for both single-phase or poly

  17. Transformer-based asymmetrical embedded Z-source neutral point clamped inverters with continuous input current and enhanced voltage boost capability

    DEFF Research Database (Denmark)

    Mo, W.; Loh, Poh Chiang; Blaabjerg, Frede

    2013-01-01

    Z-source Neutral Point Clamped (NPC) inverters were introduced to integrate both the advantages of Z-source inverters and NPC inverters. However, traditional Z-source inverters suffer from high voltage stress and chopping input current. This paper proposes six types transformer-based impedance-so......-source NPC inverters which have enhanced voltage boost capability and continuous input current by utilizing of transformer and embedded dc source configuration. Experimental results are presented to verify the theory validation....

  18. Continentward-dipping detachment fault system and asymmetric rift structure of the Baiyun Sag, northern South China Sea

    Science.gov (United States)

    Zhou, Zhichao; Mei, Lianfu; Liu, Jun; Zheng, Jinyun; Chen, Liang; Hao, Shihao

    2018-02-01

    The rift architecture and deep crustal structure of the distal margin at the mid-northern margin of the South China Sea have been previously investigated by using deep seismic reflection profiles. However, one fundamental recurring problem in the debate is the extensional fault system and rift structure of the hyperextended rift basins (Baiyun Sag and Liwan Sag) within the distal margin because of the limited amount of seismic data. Based on new 3D seismic survey data and 2D seismic reflection profiles, we observe an array of fault blocks in the Baiyun Sag, which were tilted towards the ocean by extensional faulting. The extensional faults consistently dip towards the continent. Beneath the tilted fault blocks and extensional faults, a low-angle, high-amplitude and continuous reflection has been interpreted as the master detachment surface that controls the extension process. During rifting, the continentward-dipping normal faults evolved in a sequence from south to north, generating the asymmetric rift structure of the Baiyun Sag. The Baiyun Sag is separated from the oceanic domain by a series of structural highs that were uplifted by magmatic activity in response to the continental breakup at 33 Ma and a ridge jump to the south at 26-24 Ma. Therefore, we propose that magmatism played a significant role in the continental extension and final breakup in the South China Sea.

  19. Evidence that antibodies against recombinant SnSAG1 of Sarcocystis neurona merozoites are involved in infection and immunity in equine protozoal myeloencephalitis.

    Science.gov (United States)

    Ellison, Siobhan; Witonsky, Sharon

    2009-07-01

    Sarcocystis neurona is the principal etiologic agent of equine protozoal myeloencephalitis (EPM). An immunodominant protein of S. neurona, SnSAG-1, is expressed by the majority of S. neurona merozoites isolated from spinal tissues of horses diagnosed with EPM and may be a candidate for diagnostic tests and prophylaxis for EPM. Five horses were vaccinated with adjuvanted recombinant SnSAG1 (rSnSAG1) and 5 control (sham vaccinated) horses were vaccinated with adjuvant only. Serum was evaluated pre- and post-vaccination, prior to challenge, for antibodies against rSnSAG1 and inhibitory effects on the infectivity of S. neurona by an in vitro serum neutralization assay. The effect of vaccination with rSnSAG1 on in vivo infection by S. neurona was evaluated by challenging all the horses with S. neurona merozoites. Blinded daily examinations and 4 blinded neurological examinations were used to evaluate the presence of clinical signs of EPM. The 5 vaccinated horses developed serum and cerebrospinal fluid (CSF) titers of SnSAG1, detected by enzyme-linked immunosorbent assay (ELISA), post-vaccination. Post-vaccination serum from vaccinated horses was found to have an inhibitory effect on merozoites, demonstrated by in vitro bioassay. Following the challenge, the 5 control horses displayed clinical signs of EPM, including ataxia. While 4 of the 5 vaccinated horses did not become ataxic. One rSnSAG-1 vaccinated horse showed paresis in 1 limb with muscle atrophy. All horses showed mild, transient, cranial nerve deficits; however, disease did not progress to ataxia in rSnSAG-1 vaccinated horses. The study showed that vaccination with rSnSAG-1 produced antibodies in horses that neutralized merozoites when tested by in vitro culture and significantly reduced clinical signs demonstrated by in vivo challenge.

  20. Comparative study of microcontroller controlled four-wire voltage and current source shunt active power filters

    Energy Technology Data Exchange (ETDEWEB)

    Pettersson, S.

    2009-07-01

    During the past two decades, active power filters have increasingly grown their popularity as a viable method for improving electric power quality. The main reasons for this have been the advent of fast self-commutating solid-state devices, the progression of digital technology and the improved sensor technology. Four-wire active power filters provide an efficient solution for improving the quality of supply in grounded three-phase systems or three-phase systems with neutral conductors, which are commonly used for powering residential, office and public buildings. Four-wire active power filters are applicable in compensating current harmonics, reactive power, neutral current and load phase imbalance.This thesis presents a comparative study of microcontroller controlled four-wire voltage and current source shunt active power filters. The study includes two voltage source topologies and a current source topology with two different dc-link energy storage structures, which are compared on the basis of their filtering properties, filtering performance and efficiency. The obtained results are used for determining the suitability of current source technology for four-wire active power filtering and finding the most viable four-wire shunt active power filter topology. One commonly recognized disadvantage of the current source active power filter has always been the bulky dc-link inductor. To reduce the size of the dc-link inductor, an alternative dc-link structure for current source active power filters was introduced in the late 80's. The hybrid energy storage consists of both inductive and capacitive energy storage elements, two diodes and two controllable semiconductor switching devices. Since the capacitive element is used as a main storage unit, the inductance of the dc-link inductor can be considerably reduced. However, the original dc current control method proposed is not able to utilize the full potential of the hybrid energy storage and the inductance

  1. A Circulating-Current Suppression Method for Parallel-Connected Voltage-Source Inverters With Common DC and AC Buses

    DEFF Research Database (Denmark)

    Wei, Baoze; Guerrero, Josep M.; Quintero, Juan Carlos Vasquez

    2017-01-01

    This paper presents a theoretical study with experimental validation of a circulating-current suppression method for parallel operation of three-phase voltage source inverters (VSI), which may be suitable for modular parallel uninterruptible power supply systems or hybrid AC/DC microgrid applicat......This paper presents a theoretical study with experimental validation of a circulating-current suppression method for parallel operation of three-phase voltage source inverters (VSI), which may be suitable for modular parallel uninterruptible power supply systems or hybrid AC/DC microgrid......, and added into the conventional droop plus virtual impedance control. In the control architecture, the reference voltages of the inverters are generated by the primary control loop which consists of a droop control and a virtual impedance. The secondary control is used to compensate the voltage drop...

  2. Enhancement of DFIG-Wind Turbine’s LVRT capability using novel DVR based Odd-nary Cascaded Asymmetric Multi-Level Inverter

    Directory of Open Access Journals (Sweden)

    A.D. Falehi

    2017-06-01

    Full Text Available One of the most prominent issues relevant to Doubly Fed Induction Generator (DFIG is augmentation of its Low Voltage Ride Through (LVRT capability. Dynamic Voltage Restorer (DVR is a series kind of Distributed-Flexible AC Transmission Systems (D-FACTS that is here occupied to preserve the DFIG from the voltage sag whenever a fault to be occurred in the power system. Multi-Level Inverter (MLI is the beating-heart of DVR with unique responsibility of synthesizing a staircase sinusoidal voltage from the DC voltage sources. In this regard, it is immensely important a high performance and cost-effective MLI to be embedded into the DVR. In this paper, a novel MLI is introduced to provide a staircase sinusoidal voltage with high level numbers against less switch numbers as compared to the other kinds of MLIs. By adding the bi-directional switches and capacitors of sub-MLI as well as amount of DC sources, the held forth MLI can also operate as so-called “Odd-nary” Cascaded Asymmetric Multi-Level Inverter (OCAMLI. The performance of proposed DVR based on OCAMLI i.e., DVR-OCAMLI has been thoroughly evaluated under deep and shallow balanced and unbalanced voltage sags so that its LVRT capability to be cleared up. To more scrutinize the performance of DVR-OCAMLI, it has been withal dealt with under severe and slight voltage swells as well as harmonic voltage. The accuracy and performance of DVR-OCAMLI has been furthermore compared with conventional DVR. To sum up, the relevant analytical study along with the simulation results has transparently corroborated the performance of OCAMLI as compared to other MLIs. Meanwhile, the DVR-OCAMLI has significantly compensated deep and shallow symmetric and asymmetric voltage sags to enhance the LVRT capability of DFIG; correspondingly, the severe and slight symmetric and asymmetric voltage swells as well as voltage harmonic have been exceptionally compensated as compared to conventional DVR.

  3. Direct Power Control for Three-Phase Two-Level Voltage-Source Rectifiers Based on Extended-State Observation

    DEFF Research Database (Denmark)

    Song, Zhanfeng; Tian, Yanjun; Yan, Zhuo

    2016-01-01

    This paper proposed a direct power control strategy for three-phase two-level voltage-source rectifiers based on extended-state observation. Active and reactive powers are directly regulated in the stationary reference frame. Similar to the family of predictive controllers whose inherent characte......This paper proposed a direct power control strategy for three-phase two-level voltage-source rectifiers based on extended-state observation. Active and reactive powers are directly regulated in the stationary reference frame. Similar to the family of predictive controllers whose inherent...

  4. Energy storage system in medium-sized voltage lines for the integration of decentralized fluctuating energy sources; Energiespeicher im Niederspannungsnetz zur Integration dezentraler, fluktuierender Energiequellen

    Energy Technology Data Exchange (ETDEWEB)

    Bodach, M.

    2006-06-30

    The solar radiation fluctuates due to atmospheric and planetary influences. Concerning PV systems, the changes from dark clouds to clear sky result in fast and very deep fluctuations of the time behaviour of the power output fed into the low voltage (LV) network by DC-AC-Converters. On the example of a daily recorded global radiation curve with a very short sampling time (regular interval time 1 s) the paper shows that short-term sags of the solar radiation are possible up to 80% of the previous value as a result of sudden and intensive changes of the density of the clouds. These disturbances of the quality of the generated electric power are directly transformed into the LV grids. If the number of PV systems connected to existing LV networks rises essentially, the fluctuating photovoltaic energy generation will achieve a very high importance and therefore not only the well-known, but also a lot of new problems will occur. They have already been investigated theoretically in different papers and they have also been proven quantitatively by own simulations. Improvements of the energy quality at the point of common coupling will be possible if the grid-coupled PV power plants are supplemented with suitable intelligent storage systems bridging the short-term sags. So the influence of the fluctuating radiation on the generated power can be fundamentally reduced. The developed intelligent short-term storage system smoothes out the generated power of the PV system by means of a storage. It is based on the very high capacity of an electric double layer (UltraCap, produced by EPCOS) and includes a complex electronic control system. The UltraCap has the required storing characteristics and has been adjusted to the system voltage by a highly sophisticated microprocessor controlled DC/DC-converter system. Such an intelligent storage system can also be used for the connection of other decentralised power generation units (e.g. fuel cells, block-unit heating power plant) to the

  5. Instability of Wind Turbine Converters during Current Injection to Low Voltage Grid Faults and PLL Frequency Based Stability Solution

    DEFF Research Database (Denmark)

    Göksu, Ömer; Teodorescu, Remus; Bak, Claus Leth

    2014-01-01

    In recent grid codes for wind power integration, wind turbines are required to stay connected during grid faults even when the grid voltage drops down to zero; and also to inject reactive current in proportion to the voltage drop. However, a physical fact, instability of grid-connected converters...... during current injection to very low (close to zero) voltage faults, has been omitted, i.e., failed to be noticed in the previous wind power studies and grid code revisions. In this paper, the instability of grid side converters of wind turbines defined as loss of synchronism (LOS), where the wind...... turbines lose synchronism with the grid fundamental frequency (e.g., 50 Hz) during very deep voltage sags, is explored with its theory, analyzed and a novel stability solution based on PLL frequency is proposed; and both are verified with power system simulations and by experiments on a grid...

  6. Study of southern CHAONAN sag lower continental slope basin deposition character in Northern South China Sea

    Science.gov (United States)

    Tang, Y.

    2009-12-01

    area includes three stages,that is Eogene,middle stage of lately Oligocene to early Miocene and middle Miocene to Present.Result shows that there are a good association of petroleum source rocks,reservoir rocks and seal rocks and structural traps in the Cenozoic and Mesozoic strata,as well as good conditions for the generation-migration-accumulation-preservation of petroleum in the lower continatal slope of Southern Chaoshan Sag.So the region has good petroleum prospect. Key words:Northern South China Sea;Chaoshan Sag; lower continental slope; deposition.

  7. All solid state high voltage power supply for neutral beam sources

    International Nuclear Information System (INIS)

    Praeg, W.F.

    1984-01-01

    The conceptual design of a high frequency solid state, high power, high voltage, power system that reacts fast enough to be compatible with the requirements of a neutral beam source is presented. The system offers the potential of significant advantages over conventional power line frequency systems; such as high reliability, long life, relatively little maintenance requirements, compact size and modular design

  8. Thermal-history reconstruction of the Baiyun Sag in the deep-water area of the Pearl River Mouth Basin, northern South China Sea

    Science.gov (United States)

    Tang, Xiaoyin; Yang, Shuchun; Hu, Shengbiao

    2017-11-01

    The Baiyun Sag, located in the deep-water area of the northern South China Sea, is the largest and deepest subbasin in the Pearl River Mouth Basin and one of the most important hydrocarbon-accumulation depression areas in China. Thermal history is widely thought to be of great importance in oil and gas potential assessment of a basin as it controls the timing of hydrocarbon generation and expulsion from the source rock. In order to unravel the paleo-heat flow of the Baiyun Sag, we first analyzed tectonic subsidence of 55 pseudo-wells constructed based on newly interpreted seismic profiles, along with three drilled wells. We then carried out thermal modeling using the multi-stage finite stretching method and calibrated the results using collected present-day vitrinite reflectance data and temperature data. Results indicate that the first and second heating of the Baiyun Sag after 49 Ma ceased at 33.9 Ma and 23 Ma. Reconstructed average basal paleoheat flow values at the end of the rifting periods are 57.7-86.2 mW/m2 and 66.7-97.3 mW/m2, respectively. Following the last heating period at 23 Ma, the study area has undergone a persistent thermal attenuation phase, and basal heat flow has cooled down to 64.0-79.2 mW/m2 at present.

  9. Optimal Cable Tension Distribution of the High-Speed Redundant Driven Camera Robots Considering Cable Sag and Inertia Effects

    Directory of Open Access Journals (Sweden)

    Yu Su

    2014-03-01

    Full Text Available Camera robots are high-speed redundantly cable-driven parallel manipulators that realize the aerial panoramic photographing. When long-span cables and high maneuverability are involved, the effects of cable sags and inertias on the dynamics must be carefully dealt with. This paper is devoted to the optimal cable tension distribution (OCTD for short of the camera robots. Firstly, each fast varying-length cable is discretized into some nodes for computing the cable inertias. Secondly, the dynamic equation integrated with the cable inertias is set up regarding the large-span cables as catenaries. Thirdly, an iterative optimization algorithm is introduced for the cable tension distribution by using the dynamic equation and sag-to-span ratios as constraint conditions. Finally, numerical examples are presented to demonstrate the effects of cable sags and inertias on determining tensions. The results justify the convergence and effectiveness of the algorithm. In addition, the results show that it is necessary to take the cable sags and inertias into consideration for the large-span manipulators.

  10. Over-expression of 60s ribosomal L23a is associated with cellular proliferation in SAG resistant clinical isolates of Leishmania donovani.

    Directory of Open Access Journals (Sweden)

    Sanchita Das

    Full Text Available Sodium antimony gluconate (SAG unresponsiveness of Leishmania donovani (Ld had effectively compromised the chemotherapeutic potential of SAG. 60s ribosomal L23a (60sRL23a, identified as one of the over-expressed protein in different resistant strains of L.donovani as observed with differential proteomics studies indicates towards its possible involvement in SAG resistance in L.donovani. In the present study 60sRL23a has been characterized for its probable association with SAG resistance mechanism.The expression profile of 60s ribosomal L23a (60sRL23a was checked in different SAG resistant as well as sensitive strains of L.donovani clinical isolates by real-time PCR and western blotting and was found to be up-regulated in resistant strains. Ld60sRL23a was cloned, expressed in E.coli system and purified for raising antibody in swiss mice and was observed to have cytosolic localization in L.donovani. 60sRL23a was further over-expressed in sensitive strain of L.donovani to check its sensitivity profile against SAG (Sb V and III and was found to be altered towards the resistant mode.This study reports for the first time that the over expression of 60sRL23a in SAG sensitive parasite decreases the sensitivity of the parasite towards SAG, miltefosine and paramomycin. Growth curve of the tranfectants further indicated the proliferative potential of 60sRL23a assisting the parasite survival and reaffirming the extra ribosomal role of 60sRL23a. The study thus indicates towards the role of the protein in lowering and redistributing the drug pressure by increased proliferation of parasites and warrants further longitudinal study to understand the underlying mechanism.

  11. Coordinated single-phase control scheme for voltage unbalance reduction in low voltage network.

    Science.gov (United States)

    Pullaguram, Deepak; Mishra, Sukumar; Senroy, Nilanjan

    2017-08-13

    Low voltage (LV) distribution systems are typically unbalanced in nature due to unbalanced loading and unsymmetrical line configuration. This situation is further aggravated by single-phase power injections. A coordinated control scheme is proposed for single-phase sources, to reduce voltage unbalance. A consensus-based coordination is achieved using a multi-agent system, where each agent estimates the averaged global voltage and current magnitudes of individual phases in the LV network. These estimated values are used to modify the reference power of individual single-phase sources, to ensure system-wide balanced voltages and proper power sharing among sources connected to the same phase. Further, the high X / R ratio of the filter, used in the inverter of the single-phase source, enables control of reactive power, to minimize voltage unbalance locally. The proposed scheme is validated by simulating a LV distribution network with multiple single-phase sources subjected to various perturbations.This article is part of the themed issue 'Energy management: flexibility, risk and optimization'. © 2017 The Author(s).

  12. Study on model current predictive control method of PV grid- connected inverters systems with voltage sag

    Science.gov (United States)

    Jin, N.; Yang, F.; Shang, S. Y.; Tao, T.; Liu, J. S.

    2016-08-01

    According to the limitations of the LVRT technology of traditional photovoltaic inverter existed, this paper proposes a low voltage ride through (LVRT) control method based on model current predictive control (MCPC). This method can effectively improve the photovoltaic inverter output characteristics and response speed. The MCPC method of photovoltaic grid-connected inverter designed, the sum of the absolute value of the predictive current and the given current error is adopted as the cost function with the model predictive control method. According to the MCPC, the optimal space voltage vector is selected. Photovoltaic inverter has achieved automatically switches of priority active or reactive power control of two control modes according to the different operating states, which effectively improve the inverter capability of LVRT. The simulation and experimental results proves that the proposed method is correct and effective.

  13. Component-Minimized Buck-Boost Voltage Source Inverters

    DEFF Research Database (Denmark)

    Gao, F.; Loh, P.C.; Blaabjerg, Frede

    2007-01-01

    This paper presents the design of buck-boost B4 inverters that can be derived from either Ćuk- or SEPIC-derived buck-boost B6 inverters. Unlike traditional inverters, the integration of front-end voltage boost circuitry and inverter circuitry allows it to perform buck-boost voltage inversion...... between capacitors. Modulation wise, the proposed buck-boost B4 inverters can be controlled using a carefully designed carrier-based pulse-width modulation (PWM) scheme that will always ensure balanced threephase outputs as desired, while simultaneously achieving minimal voltage stress across...

  14. Modeling, analysis, and design of stationary reference frame droop controlled parallel three-phase voltage source inverters

    DEFF Research Database (Denmark)

    Vasquez, Juan Carlos; Guerrero, Josep M.; Savaghebi, Mehdi

    2011-01-01

    and discussed. Experimental results are provided to validate the performance and robustness of the VSIs functionality during Islanded and grid-connected operations, allowing a seamless transition between these modes through control hierarchies by regulating frequency and voltage, main-grid interactivity......Power electronics based microgrids consist of a number of voltage source inverters (VSIs) operating in parallel. In this paper, the modeling, control design, and stability analysis of three-phase VSIs are derived. The proposed voltage and current inner control loops and the mathematical models...

  15. Voltage control in Z-source inverter using low cost microcontroller for undergraduate approach

    Science.gov (United States)

    Zulkifli, Shamsul Aizam; Sewang, Mohd Rizal; Salimin, Suriana; Shah, Noor Mazliza Badrul

    2017-09-01

    This paper is focussing on controlling the output voltage of Z-Source Inverter (ZSI) using a low cost microcontroller with MATLAB-Simulink that has been used for interfacing the voltage control at the output of ZSI. The key advantage of this system is the ability of a low cost microcontroller to process the voltage control blocks based on the mathematical equations created in MATLAB-Simulink. The Proportional Integral (PI) control equations are been applied and then, been downloaded to the microcontroller for observing the changes on the voltage output regarding to the changes on the reference on the PI. The system has been simulated in MATLAB and been verified with the hardware setup. As the results, the Raspberry Pi and Arduino that have been used in this work are able to respond well when there is a change of ZSI output. It proofed that, by applying/introducing this method to student in undergraduate level, it will help the student to understand more on the process of the power converter combine with a control feedback function that can be applied at low cost microcontroller.

  16. An improved design of virtual output impedance loop for droop-controlled parallel three-phase Voltage Source Inverters

    DEFF Research Database (Denmark)

    Wang, Xiongfei; Blaabjerg, Frede; Chen, Zhe

    2012-01-01

    -sequence virtual resistance even in the case of feeding a balanced three-phase load. Furthermore, to adapt to the variety of unbalanced loads, a dynamically-tuned negative-sequence resistance loop is designed, such that a good compromise between the quality of inverter output voltage and the performance of load......The virtual output impedance loop is known as an effective way to enhance the load sharing stability and quality of droop-controlled parallel inverters. This paper proposes an improved design of virtual output impedance loop for parallel three-phase voltage source inverters. In the approach...... sharing can be obtained. Finally, laboratory test results of two parallel three-phase voltage source inverters are shown to confirm the validity of the proposed method....

  17. Impact of the Converter Control Strategies on the Drive Train of Wind Turbine during Voltage Dips

    Directory of Open Access Journals (Sweden)

    Fenglin Miao

    2015-10-01

    Full Text Available The impact of converter control strategies on the drive train of wind turbines during voltage dips is investigated in this paper using a full electromechanical model. Aerodynamics and tower vibration are taken into consideration by means of a simulation program, named FAST. Detailed gearbox and electrical subsystems are represented in MATLAB. The dynamic response of electromagnetic torque and its impact on the mechanical variables are the concern in this paper and the response of electrical variables is less discussed. From the mechanical aspects, the effect of rising power recovery speed and unsymmetrical voltage dips are analyzed on the basis of the dynamic response of the high-speed shaft (HSS. A comparison of the impact on the drive train is made for two converter control strategies during small voltage dips. Through the analysis of torque, speed and tower vibration, the results indicate that both power recovery speed and the sudden torque sag have a significant impact on drive trains, and the effects depend on the different control strategies. Moreover, resonance might be excited on the drive train by an unbalanced voltage.

  18. Mitigation of Grid Current Distortion for LCL-Filtered Voltage Source Inverter with Inverter Current Feedback Control

    DEFF Research Database (Denmark)

    Xin, Zhen; Mattavelli, Paolo; Yao, WenLi

    2018-01-01

    LCL filters feature low inductance; thus, the injected grid current from an LCL-filtered Voltage Source Inverter (VSI) can be easily distorted by grid voltage harmonics. This problem is especially tough for the control system with Inverter-side Current Feedback (ICF), since the grid current...... harmonics can freely flow into the filter capacitor. In this case, because of the loss of harmonic information, traditional harmonic controllers fail to mitigate the grid current distortion. Although this problem may be avoided using the grid voltage feedforward scheme, the required differentiators may...

  19. 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. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.

  20. Deriving Sight Distance on a Compound Sag and Circular Curve in a Three Dimensional Space

    Directory of Open Access Journals (Sweden)

    Chiu Liu, PhD, PE, PTOE

    2012-09-01

    Full Text Available Insufficient roadway sight distance (SD may become a contribution factor to traffic collisions or other unsafe traffic maneuvers. The sight distance (SD for a two-dimensional (2-d sag or circular curve has been addressed in detail in various traffic engineering literatures. Although three-dimensional (3-d compound sag and circular curves are often found along ramps, connectors, and mountain roads, the sight distances for these compound curves are yet to be analyzed on an exact analytic setting. By considering human-vehicle-roadway interaction, the formulas for computing the SD on a 3-d curve are derived the first time on a unified analytic framework. The 2-d sag curve SD can also be deduced from these derived formulas as special limiting cases. Practitioners can easily program these formulas or equations on a user-friendly Microsoft Excel spread sheet to calculate 3-d SD on most roadways with roadside clearance. This framework can be extended to estimate SD on roadways with obstacles partially blocking vehicle headlight beams. 6.

  1. Improved fault ride through capability of DFIG based wind turbines using synchronous reference frame control based dynamic voltage restorer.

    Science.gov (United States)

    Rini Ann Jerin, A; Kaliannan, Palanisamy; Subramaniam, Umashankar

    2017-09-01

    Fault ride through (FRT) capability in wind turbines to maintain the grid stability during faults has become mandatory with the increasing grid penetration of wind energy. Doubly fed induction generator based wind turbine (DFIG-WT) is the most popularly utilized type of generator but highly susceptible to the voltage disturbances in grid. Dynamic voltage restorer (DVR) based external FRT capability improvement is considered. Since DVR is capable of providing fast voltage sag mitigation during faults and can maintain the nominal operating conditions for DFIG-WT. The effectiveness of the DVR using Synchronous reference frame (SRF) control is investigated for FRT capability in DFIG-WT during both balanced and unbalanced fault conditions. The operation of DVR is confirmed using time-domain simulation in MATLAB/Simulink using 1.5MW DFIG-WT. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

  2. FPGA Techniques Based New Hybrid Modulation Strategies for Voltage Source Inverters

    Science.gov (United States)

    Sudha, L. U.; Baskaran, J.; Elankurisil, S. A.

    2015-01-01

    This paper corroborates three different hybrid modulation strategies suitable for single-phase voltage source inverter. The proposed method is formulated using fundamental switching and carrier based pulse width modulation methods. The main tale of this proposed method is to optimize a specific performance criterion, such as minimization of the total harmonic distortion (THD), lower order harmonics, switching losses, and heat losses. The proposed method is articulated using fundamental switching and carrier based pulse width modulation methods. Thus, the harmonic pollution in the power system will be reduced and the power quality will be augmented with better harmonic profile for a target fundamental output voltage. The proposed modulation strategies are simulated in MATLAB r2010a and implemented in a Xilinx spartan 3E-500 FG 320 FPGA processor. The feasibility of these modulation strategies is authenticated through simulation and experimental results. PMID:25821852

  3. Grid Filter Design for a Multi-Megawatt Medium-Voltage Voltage Source Inverter

    DEFF Research Database (Denmark)

    Rockhill, A.A.; Liserre, Marco; Teodorescu, Remus

    2011-01-01

    This paper describes the design procedure and performance of an LCL grid filter for a medium-voltage neutral point clamped (NPC) converter to be adopted for a multimegawatt wind turbine. The unique filter design challenges in this application are driven by a combination of the medium voltage...... converter, a limited allowable switching frequency, component physical size and weight concerns, and the stringent limits for allowable injected current harmonics. Traditional design procedures of grid filters for lower power and higher switching frequency converters are not valid for a multi......-megawatt filter connecting a medium-voltage converter switching at low frequency to the electric grid. This paper demonstrates a frequency domain model based approach to determine the optimum filter parameters that provide the necessary performance under all operating conditions given the necessary design...

  4. Effects of detector-source distance and detector bias voltage variations on time resolution of general purpose plastic scintillation detectors.

    Science.gov (United States)

    Ermis, E E; Celiktas, C

    2012-12-01

    Effects of source-detector distance and the detector bias voltage variations on time resolution of a general purpose plastic scintillation detector such as BC400 were investigated. (133)Ba and (207)Bi calibration sources with and without collimator were used in the present work. Optimum source-detector distance and bias voltage values were determined for the best time resolution by using leading edge timing method. Effect of the collimator usage on time resolution was also investigated. Copyright © 2012 Elsevier Ltd. All rights reserved.

  5. Design and Control of Parallel Three Phase Voltage Source Inverters in Low Voltage AC Microgrid

    Directory of Open Access Journals (Sweden)

    El Hassane Margoum

    2017-01-01

    Full Text Available Design and hierarchical control of three phase parallel Voltage Source Inverters are developed in this paper. The control scheme is based on synchronous reference frame and consists of primary and secondary control levels. The primary control consists of the droop control and the virtual output impedance loops. This control level is designed to share the active and reactive power correctly between the connected VSIs in order to avoid the undesired circulating current and overload of the connected VSIs. The secondary control is designed to clear the magnitude and the frequency deviations caused by the primary control. The control structure is validated through dynamics simulations.The obtained results demonstrate the effectiveness of the control structure.

  6. Survey of the rubber tree genome reveals a high number of cysteine protease-encoding genes homologous to Arabidopsis SAG12.

    Science.gov (United States)

    Zou, Zhi; Liu, Jianting; Yang, Lifu; Xie, Guishui

    2017-01-01

    Arabidopsis thaliana SAG12, a senescence-specific gene encoding a cysteine protease, is widely used as a molecular marker for the study of leaf senescence. To date, its potential orthologues have been isolated from several plant species such as Brassica napus and Nicotiana tabacum. However, little information is available in rubber tree (Hevea brasiliensis), a rubber-producing plant of the Euphorbiaceae family. This study presents the identification of SAG12-like genes from the rubber tree genome. Results showed that an unexpected high number of 17 rubber orthologues with a single intron were found, contrasting the single copy with two introns in Arabidopsis. The gene expansion was also observed in another two Euphorbiaceae plants, castor bean (Ricinus communis) and physic nut (Jatropha curcas), both of which contain 8 orthologues. In accordance with no occurrence of recent whole-genome duplication (WGD) events, most duplicates in castor and physic nut were resulted from tandem duplications. In contrast, the duplicated HbSAG12H genes were derived from tandem duplications as well as the recent WGD. Expression analysis showed that most HbSAG12H genes were lowly expressed in examined tissues except for root and male flower. Furthermore, HbSAG12H1 exhibits a strictly senescence-associated expression pattern in rubber tree leaves, and thus can be used as a marker gene for the study of senescence mechanism in Hevea.

  7. Unified Impedance Model of Grid-Connected Voltage-Source Converters

    DEFF Research Database (Denmark)

    Wang, Xiongfei; Harnefors, Lennart; Blaabjerg, Frede

    2018-01-01

    This paper proposes a unified impedance model of grid-connected voltage-source converters for analyzing dynamic influences of the Phase-Locked Loop (PLL) and current control. The mathematical relations between the impedance models in the different domains are first explicitly revealed by means...... of complex transfer functions and complex space vectors. A stationary (αβ-) frame impedance model is then proposed, which not only predicts the stability impact of the PLL, but reveals also its frequency coupling effect explicitly. Furthermore, the impedance shaping effect of the PLL on the current control...... results and theoretical analysis confirm the effectiveness of the stationary-frame impedance model....

  8. Down-regulation of OsSAG12-1 results in enhanced senescence ...

    Indian Academy of Sciences (India)

    2013-07-22

    Jul 22, 2013 ... vides staple food nearly half of the world's population and accounts .... Healthy and fresh onion ... served domain comprising approximate 210 aa belongs to the peptidase ..... Lim PO, Kim HJ and Nam HG 2007 Leaf senescence. Annu. Rev. ... Effects of P(SAG12)-IPT gene expression on development and.

  9. SAG2 locus genotyping of Toxoplasma gondii in meat products of ...

    African Journals Online (AJOL)

    Jane

    2011-10-12

    Oct 12, 2011 ... restriction fragment length polymorphism (RFLP) analysis of SAG2 locus revealed that all of the samples belonged to genotype I. The detection of the parasite in uncooked meat and commercial meat products, and the high ratio of seropositive slaughtered animals, emphasis that the risk still exists for.

  10. Ultra Low-Voltage Energy Harvesting

    Science.gov (United States)

    2013-09-01

    if in a solar battery charger the level of illumination were to drop due to cloud cover, the diode would prevent discharging of the battery when...the source voltage becomes lower than battery voltage. The drawback of a simple circuit like this is that once the source voltage is lower than the...longer charged when the battery voltage is above the OV setting. Figure 13. Block diagram of BQ25504 circuit . (From [10]) 18 THIS PAGE

  11. SAG/ROC-SCFβ-TrCP E3 Ubiquitin Ligase Promotes Pro-Caspase-3 Degradation as a Mechanism of Apoptosis Protection

    Directory of Open Access Journals (Sweden)

    Mingjia Tan

    2006-12-01

    Full Text Available Skp1-cullin-F-box protein (SCF is a multicomponent E3 ubiquitin (Ub ligase that ubiquitinates a number of important biologic molecules such as p27, β-catenin, and lκB for proteasomal degradation, thus regulating cell proliferation and survival. One SCF component, SAG/ROC2/Rbx2/Hrt2, a RING finger protein, was first identified as a redox-inducible protein, which, when overexpressed, inhibited apoptosis both in vitro and in vivo. We report here that sensitive to apoptosis gene (SAG, as well as its family member ROC1/Rbxi, bound to the proinactive form of caspase-3 (pro-caspase-3. Binding was likely mediated through F-box protein, β-transducin repeat-containing protein (β-TrCP, which binds to the first 38 amino acids of pro-caspase-3. Importantly, β-TrCP1 expression significantly shortened the protein half-life of pro-caspase-3, whereas expression of a dominant-negative β-TrCP1 mutant with the F-box domain deleted extended it. An in vitro ubiquitination assay showed that SAG/ROC-SCF -Trcp promoted ubiquitination of pro-caspase-3. Furthermore, endogenous levels of pro-caspase-3 were decreased by overexpression of SAG/ROC-SCFβ-TrCP E3 Ub ligases, but increased on siRNA silencing of SAG, regulator of cullin-1 (ROC1, or β-TrCPs, leading to increased apoptosis by etoposide and TNF-related apoptosis-inducing ligand through increased activation of caspase-3. Thus, pro-caspase-3 appears to be a substrate of SAG/ROC-SCFβ-TrCP E3 Ub ligase, which protects cells from apoptosis through increased apoptosis threshold by reducing the basal level of pro-caspase-3.

  12. Balanced Current Control Strategy for Current Source Rectifier Stage of Indirect Matrix Converter under Unbalanced Grid Voltage Conditions

    Directory of Open Access Journals (Sweden)

    Yeongsu Bak

    2016-12-01

    Full Text Available This paper proposes a balanced current control strategy for the current source rectifier (CSR stage of an indirect matrix converter (IMC under unbalanced grid voltage conditions. If the three-phase grid connected to the voltage source inverter (VSI of the IMC has unbalanced voltage conditions, it affects the currents of the CSR stage and VSI stage, and the currents are distorted. Above all, the distorted currents of the CSR stage cause instability in the overall system, which can affect the life span of the system. Therefore, in this paper, a control strategy for balanced currents in the CSR stage is proposed. To achieve balanced currents in the CSR stage, the VSI stage should receive DC power without ripple components from the CSR stage. This is implemented by controlling the currents in the VSI stage. Therefore, the proposed control strategy decouples the positive and negative phase-sequence components existing in the unbalanced voltages and currents of the VSI stage. Using the proposed control strategy under unbalanced grid voltage conditions, the stability and life span of the overall system can be improved. The effectiveness of the proposed control strategy is verified by simulation and experimental results.

  13. Passivity-Based Control by Series/Parallel Damping of Single-Phase PWM Voltage Source Converter

    NARCIS (Netherlands)

    del Puerto Flores, Dunstano; Scherpen, Jacqueline; Liserre, Marco; de Vries, Martijn M. J.; Kransse, Marco J.; Monopoli, Vito Giuseppe

    This paper describes a detailed design procedure for passivity-based controllers developed using the Brayton-Moser (BM) framework. Several passivity-based feedback designs are presented for the voltage-source converter, specifically for the H-bridge converter, since nowadays it is one of the

  14. Interest of retro-anal levator plate myorrhaphy in selected cases of descending perineum syndrome with positive anti-sagging test

    Directory of Open Access Journals (Sweden)

    Beco Jacques

    2008-07-01

    Full Text Available Abstract Background Levator plate sagging (LPS, usually called descending perineum syndrome, is one of the main defects encountered in perineology. This defect is classically associated with colo-proctologic functional troubles (dyschesia and anal incontinence but can also induce perineodynia, gynaecological and lower urinary tract symptoms. Methods A retrospective case series of nine female patients (mean age: 44.3 underwent an isolated retro-anal levator plate myorrhaphy (RLPM to treat symptomatic LPS confirmed by rectal examination and/or Perineocaliper®. An anti-sagging test (support of the posterior perineum must significantly improve the symptoms that were resistant to conservative treatment. The effect of the procedure on the symptoms of the 3 axes of the perineum (urological, colo-proctologic and gynecological and on perineodynia was evaluated during a follow up consultation more than 9 months after surgery. The effect of RLPM on the position of the anal margin and on the levator plate angle was studied using rectal examination, Perineocaliper® and retro-anal ultrasound. Results Before surgery, anti-sagging tests were positive for dyschesia, urinary urgency and pain. After a mean follow-up of 16.1 months, RLPM resolved or improved 2/2 cases of stress urinary incontinence, 3/5 of urinary urgency, 3/4 of dysuria, 3/3 of anal incontinence, 7/8 of dyschesia, 3/4 of cystocele, 4/5 of rectocele, 5/8 of dyspareunia and 6/7 of perineodynia. Rectal examination showed a complete suppression of sagging in 4 patients and an improvement in the 5 others. The mean reduction of perineal descent was 1.08 cm (extremes: 0–1.5. Using retro-anal ultrasound of the levator plate, the mean reduction of sagging was 12.67 degrees (extremes: 1 – 21. Conclusion Anti-sagging tests can be used before surgery to simulate the effect of RLPM. This surgical procedure seems to improve stress urinary incontinence, frequency, nocturia, urgency, dysuria, anal

  15. Grid Voltage Modulated Control of Grid-Connected Voltage Source Inverters under Unbalanced Grid Conditions

    DEFF Research Database (Denmark)

    Li, Mingshen; Gui, Yonghao; Quintero, Juan Carlos Vasquez

    2017-01-01

    In this paper, an improved grid voltage modulated control (GVM) with power compensation is proposed for grid-connected voltage inverters when the grid voltage is unbalanced. The objective of the proposed control is to remove the power ripple and to improve current quality. Three power compensation...... objectives are selected to eliminate the negative sequence components of currents. The modified GVM method is designed to obtain two separate second-order systems for not only the fast convergence rate of the instantaneous active and reactive powers but also the robust performance. In addition, this method...

  16. Multilevel Converter by Cascading Two-Level Three-Phase Voltage Source Converter

    Directory of Open Access Journals (Sweden)

    Abdullrahman A. Al-Shamma’a

    2018-04-01

    Full Text Available This paper proposes a topology using isolated, cascaded multilevel voltage source converters (VSCs and employing two-winding magnetic elements for high-power applications. The proposed topology synthesizes 6 two-level, three-phase VSCs, so the power capability of the presented converter is six times the capability of each VSC module. The characteristics of the proposed topology are demonstrated through analyzing its current relationships, voltage relationships and power capability in detail. The power rating is equally shared among the VSC modules without the need for a sharing algorithm; thus, the converter operates as a single three-phase VSC. The comparative analysis with classical neutral-point clamped, flying capacitor and cascaded H-bridge exhibits the superior features of fewer insulated gate bipolar transistors (IGBTs, capacitor requirement and fewer diodes. To validate the theoretical performance of the proposed converter, it is simulated in a MATLAB/Simulink environment and the results are experimentally demonstrated using a laboratory prototype.

  17. The rice OsSAG12-2 gene codes for a functional protease that ...

    Indian Academy of Sciences (India)

    2016-07-11

    Jul 11, 2016 ... Senescence is the final stage of plant development. Although ... Down-regulation of OsSAG12-1 in transgenic rice .... Plants were germinated on soil and grown for 15 days under normal conditions before taking photograph.

  18. Evolution of depositional system and uraniferous characteristics of Damoguaihe formation in Kelulun sag

    International Nuclear Information System (INIS)

    Zhang Zhijie; Yu Xinghe; Zhang Chuanheng; Chen Zhankun

    2005-01-01

    Damoguaihe Formation, which is mainly of alluvial fan, fan delta and lacustrine depositional systems, is the target horizon for the prospecting of sandstone-type uranium deposit in Kelulun sag, Hailaer basin. According to the depositional environment and sediment characteristics, alluvial fan facies is subdivided into upper fan, middle fan and lower fan subfacies; the fan delta facies is subadivided into upper fan delta plain, lower fan delta plain, fan delta front and fan prodelta subfacies. At the northern edge of the sag occurred one fan delta and one alluvial fan, which can mutually transform one into another. The terrigenous coarse-grained clastic deposits in the study area provide favorable condition for the concentration of uranium and especially the main channels and distributary channels on the fan delta and alluvial fan are the most favorable sites for uranium concentration. (authors)

  19. A Method for the Realization of an Interruption Generator Based on Voltage Source Converters

    Directory of Open Access Journals (Sweden)

    Junhui Li

    2017-10-01

    Full Text Available In this paper we described the structure and working principle of an interruption generator based on voltage source converters (VSCs. The main circuit parameters of the VSCs are determined according to the target of power transfer capability, harmonic suppression, and dynamic response capability. A state feedback linearization method in nonlinear differential geometry theory was used for dq axis current decoupling, based on the mathematical model used in the dq coordinate system of VSCs. The direct current control strategy was adopted to achieve the independent regulation of active power and reactive power. The proportional integral (PI link was used to optimize the dynamic performance of the controller, and PI parameters were adjusted. Disturbance voltage waves were generated by the regular sampling method. PSCAD/EMTDC simulation results and physical prototype experiments showed that the device could generate various disturbance voltage waveforms steadily, and had good dynamic and steady-state performance.

  20. Fault Ride-through Capability Enhancement of Voltage Source Converter-High Voltage Direct Current Systems with Bridge Type Fault Current Limiters

    Directory of Open Access Journals (Sweden)

    Md Shafiul Alam

    2017-11-01

    Full Text Available This paper proposes the use of bridge type fault current limiters (BFCLs as a potential solution to reduce the impact of fault disturbance on voltage source converter-based high voltage DC (VSC-HVDC systems. Since VSC-HVDC systems are vulnerable to faults, it is essential to enhance the fault ride-through (FRT capability with auxiliary control devices like BFCLs. BFCL controllers have been developed to limit the fault current during the inception of system disturbances. Real and reactive power controllers for the VSC-HVDC have been developed based on current control mode. DC link voltage control has been achieved by a feedback mechanism such that net power exchange with DC link capacitor is zero. A grid-connected VSC-HVDC system and a wind farm integrated VSC-HVDC system along with the proposed BFCL and associated controllers have been implemented in a real time digital simulator (RTDS. Symmetrical three phase as well as different types of unsymmetrical faults have been applied in the systems in order to show the effectiveness of the proposed BFCL solution. DC link voltage fluctuation, machine speed and active power oscillation have been greatly suppressed with the proposed BFCL. Another significant feature of this work is that the performance of the proposed BFCL in VSC-HVDC systems is compared to that of series dynamic braking resistor (SDBR. Comparative results show that the proposed BFCL is superior over SDBR in limiting fault current as well as improving system fault ride through (FRT capability.

  1. Control Method for DC-Link Voltage Ripple Cancellation in Voltage Source Inverter under Unbalanced Three-Phase Voltage Supply Conditions

    Czech Academy of Sciences Publication Activity Database

    Chomát, Miroslav; Schreier, Luděk

    2005-01-01

    Roč. 152, č. 3 (2005), s. 494-500 ISSN 1350-2352 R&D Projects: GA ČR(CZ) GA102/02/0554 Institutional research plan: CEZ:AV0Z20570509 Keywords : DC-link voltage * unbalanced three-phase voltage Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 0.587, year: 2005

  2. Comparative Study of Modulation Techniques for Two-Level Voltage Source Inverters

    Directory of Open Access Journals (Sweden)

    Barry W. Williams

    2016-06-01

    Full Text Available A detailed comparative study of modulation techniques for single and three phase dc-ac inverters is presented.  Sinusoidal Pulse Width Modulation, Triplen Sinusoidal Pulse Width Modulation, Space Vector Modulation, Selective Harmonic Elimination and Wavelet Modulation are assessed and compared in terms of maximum fundamental output, harmonic performance, switching losses and operational mode.  The presented modulation techniques are applied to single and three phase voltage source inverters and are simulated using SIMULINK.  The simulation results clarify the inverter performance achieved using the different modulations techniques.

  3. Digital Control Techniques Based on Voltage Source Inverters in Renewable Energy Applications: A Review

    Directory of Open Access Journals (Sweden)

    Sohaib Tahir

    2018-02-01

    Full Text Available In the modern era, distributed generation is considered as an alternative source for power generation. Especially, need of the time is to provide the three-phase loads with smooth sinusoidal voltages having fixed frequency and amplitude. A common solution is the integration of power electronics converters in the systems for connecting distributed generation systems to the stand-alone loads. Thus, the presence of suitable control techniques, in the power electronic converters, for robust stability, abrupt response, optimal tracking ability and error eradication are inevitable. A comprehensive review based on design, analysis, validation of the most suitable digital control techniques and the options available for the researchers for improving the power quality is presented in this paper with their pros and cons. Comparisons based on the cost, schemes, performance, modulation techniques and coordinates system are also presented. Finally, the paper describes the performance evaluation of the control schemes on a voltage source inverter (VSI and proposes the different aspects to be considered for selecting a power electronics inverter topology, reference frames, filters, as well as control strategy.

  4. A Review of Passive Power Filters for Three-Phase Grid-Connected Voltage-Source Converters

    DEFF Research Database (Denmark)

    Beres, Remus Narcis; Wang, Xiongfei; Liserre, Marco

    2016-01-01

    and source impedances. Furthermore, the stabilizing effect is more difficult to be guaranteed for cost-optimized filters, which are characterized by low inductance and high capacitance passive components. In this paper, several passive filter topologies used to interface voltage source converters......In order to reduce size and cost, high-order passive filters are generally preferred in power converters to cancel out high frequency harmonics caused by pulse width modulation. However, the filter resonance peaks may require the use of passive dampers to stabilize the interactions between the load...

  5. Stray voltage mitigation

    Energy Technology Data Exchange (ETDEWEB)

    Jamali, B.; Piercy, R.; Dick, P. [Kinetrics Inc., Toronto, ON (Canada). Transmission and Distribution Technologies

    2008-04-09

    This report discussed issues related to farm stray voltage and evaluated mitigation strategies and costs for limiting voltage to farms. A 3-phase, 3-wire system with no neutral ground was used throughout North America before the 1930s. Transformers were connected phase to phase without any electrical connection between the primary and secondary sides of the transformers. Distribution voltage levels were then increased and multi-grounded neutral wires were added. The earth now forms a parallel return path for the neutral current that allows part of the neutral current to flow continuously through the earth. The arrangement is responsible for causing stray voltage. Stray voltage causes uneven milk production, increased incidences of mastitis, and can create a reluctance to drink water amongst cows when stray voltages are present. Off-farm sources of stray voltage include phase unbalances, undersized neutral wire, and high resistance splices on the neutral wire. Mitigation strategies for reducing stray voltage include phase balancing; conversion from single to 3-phase; increasing distribution voltage levels, and changing pole configurations. 22 refs., 5 tabs., 13 figs.

  6. Voltage regulated hybrid DC power source using supercapacitors as energy storage device

    International Nuclear Information System (INIS)

    Ayad, Mohamed-Yacine; Pierfederici, Serge; Rael, Stephane; Davat, Bernard

    2007-01-01

    The management of embedded electrical energy needs a storage system with high dynamic performances in order to shave transient power peaks and to compensate for the intrinsic limitations of the main source. The use of supercapacitors for this storage system is quite suitable because of appropriate electrical characteristics (huge capacitance, weak series resistance, high specific energy, high specific power), direct storage (energy ready for use) and easy control by power electronic conversion. This paper deals with the conception and realisation of a voltage regulated hybrid DC power source using supercapacitors as an auxiliary storage device. Here, we present the structure, control principle and results associated with experimental validation. Our interest will be focused on the management of transient power peaks

  7. Voltage regulated hybrid DC power source using supercapacitors as energy storage device

    Energy Technology Data Exchange (ETDEWEB)

    Ayad, Mohamed-Yacine; Pierfederici, Serge; Rael, Stephane; Davat, Bernard [Groupe de Recherche en Electrotechnique et Electronique de Nancy, Centre National de la Recherche Scientifique (Unite Mixte de Recherche 7037), 2, Avenue de la Foret de Haye, 54516 Vandoeuvre-les-Nancy (France)

    2007-07-15

    The management of embedded electrical energy needs a storage system with high dynamic performances in order to shave transient power peaks and to compensate for the intrinsic limitations of the main source. The use of supercapacitors for this storage system is quite suitable because of appropriate electrical characteristics (huge capacitance, weak series resistance, high specific energy, high specific power), direct storage (energy ready for use) and easy control by power electronic conversion. This paper deals with the conception and realisation of a voltage regulated hybrid DC power source using supercapacitors as an auxiliary storage device. Here, we present the structure, control principle and results associated with experimental validation. Our interest will be focused on the management of transient power peaks. (author)

  8. Grid Integration of Single Stage Solar PV System using Three-level Voltage Source Converter

    Science.gov (United States)

    Hussain, Ikhlaq; Kandpal, Maulik; Singh, Bhim

    2016-08-01

    This paper presents a single stage solar PV (photovoltaic) grid integrated power generating system using a three level voltage source converter (VSC) operating at low switching frequency of 900 Hz with robust synchronizing phase locked loop (RS-PLL) based control algorithm. To track the maximum power from solar PV array, an incremental conductance algorithm is used and this maximum power is fed to the grid via three-level VSC. The use of single stage system with three level VSC offers the advantage of low switching losses and the operation at high voltages and high power which results in enhancement of power quality in the proposed system. Simulated results validate the design and control algorithm under steady state and dynamic conditions.

  9. A Review of Passive Filters for Grid-Connected Voltage Source Converters

    DEFF Research Database (Denmark)

    Beres, Remus Narcis; Wang, Xiongfei; Blaabjerg, Frede

    2014-01-01

    LCL filter is the common interface between the Pulse Width Modulated Voltage Source Converter (PWM VSC) and the utility grid due to high harmonic attenuation capability and reduced size of the passive elements. The present paper investigates the most promising passive damping methods for the LCL...... topology but also propose an overview of high order filters capable to offer even more attenuation than the LCL filter at a reduced size. This is the case of more recently introduced LCL topology with tuned traps. However, it is shown that by decreasing the size of the passive elements the robustness...

  10. Biological Mechanisms Underlying the Ultraviolet Radiation-Induced Formation of Skin Wrinkling and Sagging I: Reduced Skin Elasticity, Highly Associated with Enhanced Dermal Elastase Activity, Triggers Wrinkling and Sagging

    Science.gov (United States)

    Imokawa, Genji; Ishida, Koichi

    2015-01-01

    The repetitive exposure of skin to ultraviolet B (UVB) preferentially elicits wrinkling while ultraviolet A (UVA) predominantly elicits sagging. In chronically UVB or UVA-exposed rat skin there is a similar tortuous deformation of elastic fibers together with decreased skin elasticity, whose magnitudes are greater in UVB-exposed skin than in UVA-exposed skin. Comparison of skin elasticity with the activity of matrix metalloproteinases (MMPs) in the dermis of ovariectomized rats after UVB or UVA irradiation demonstrates that skin elasticity is more significantly decreased in ovariectomized rats than in sham-operated rats, which is accompanied by a reciprocal increase in elastase activity but not in the activities of collagenases I or IV. Clinical studies using animal skin and human facial skin demonstrated that topical treatment with a specific inhibitor or an inhibitory extract of skin fibroblast-derived elastase distinctly attenuates UVB and sunlight-induced formation of wrinkling. Our results strongly indicated that the upregulated activity of skin fibroblast-derived elastase plays a pivotal role in wrinkling and/or sagging of the skin via the impairment of elastic fiber configuration and the subsequent loss of skin elasticity. PMID:25856675

  11. Reliability of supply of switchgear for auxiliary low voltage in substations extra high voltage to high voltage

    Directory of Open Access Journals (Sweden)

    Perić Dragoslav M.

    2015-01-01

    Full Text Available Switchgear for auxiliary low voltage in substations (SS of extra high voltages (EHV to high voltage (HV - SS EHV/HV kV/kV is of special interest for the functioning of these important SS, as it provides a supply for system of protection and other vital functions of SS. The article addresses several characteristic examples involving MV lines with varying degrees of independence of their supply, and the possible application of direct transformation EHV/LV through special voltage transformers. Auxiliary sources such as inverters and diesel generators, which have limited power and expensive energy, are also used for the supply of switchgear for auxiliary low voltage. Corresponding reliability indices are calculated for all examples including mean expected annual engagement of diesel generators. The applicability of certain solutions of switchgear for auxiliary low voltage SS EHV/HV, taking into account their reliability, feasibility and cost-effectiveness is analyzed too. In particular, the analysis of applications of direct transformation EHV/LV for supply of switchgear for auxiliary low voltage, for both new and existing SS EHV/HV.

  12. Symmetric voltage-controlled variable resistance

    Science.gov (United States)

    Vanelli, J. C.

    1978-01-01

    Feedback network makes resistance of field-effect transistor (FET) same for current flowing in either direction. It combines control voltage with source and load voltages to give symmetric current/voltage characteristics. Since circuit produces same magnitude output voltage for current flowing in either direction, it introduces no offset in presense of altering polarity signals. It is therefore ideal for sensor and effector circuits in servocontrol systems.

  13. Grid to Standalone Transition Motion-Sensorless Dual-Inverter Control of PMSG With Asymmetrical Grid Voltage Sags and Harmonics Filtering

    DEFF Research Database (Denmark)

    Fatu, M.; Blaabjerg, Frede; Boldea, I.

    2014-01-01

    This paper describes a variable-speed motion-sensorless control system for permanent-magnet synchronous generator (PMSG) connected to grid via back-to-back inverters for wind energy generation. The grid-side inverter control system employs proportional-integral (PI) current controllers with cross...... and automatic seamless transfer method from grid connected to stand alone and vice versa. In stand-alone mode, a voltage control scheme with selective harmonic compensation is employed. The PMSG motion-sensorless control system uses an active power controller and a PLL-based observer to estimate the rotor...... and voltage harmonics compensation. While some of the aforementioned issues have been treated rather individually in previous conference publications of the authors, the present paper integrates them into a comprehensive control system of PMSG....

  14. Investigation of Efficiency and Thermal Performance of The Y-source Converters for a Wide Voltage Range

    Directory of Open Access Journals (Sweden)

    Brwene Salah Gadalla

    2015-12-01

    Full Text Available The Y-source topology has a unique advantage of having high voltages gain with small shoot through duty cycles. Furthermore, having the advantage of high modulation index which increase the power density and improve the performance of the converter. In this paper, a collective thermal and efficiency investigation has been performed in order to improve the reliability of the converter. Evaluation of relevant losses as ( switching, conduction, capacitor ESR, core and winding losses , and evaluation of the junction temperature of the devices under 25C ambient temperature. The analysis is done for different voltage gain factors (2, 3, and 4, and different winding factor (4, and 5 using PLECS toolbox. The results shows that the higher the voltage gain and winding factor, the higher power losses and rising in the junction temperature of the device.

  15. Fiber-optic voltage measuring system

    Science.gov (United States)

    Ye, Miaoyuan; Nie, De-Xin; Li, Yan; Peng, Yu; Lin, Qi-Qing; Wang, Jing-Gang

    1993-09-01

    A new fibre optic voltage measuring system has been developed based on the electrooptic effect of bismuth germanium oxide (Bi4Ge3O12)crystal. It uses the LED as the light source. The light beam emitted from the light source is transmitted to the sensor through the optic fibre and the intensity of the output beam is changed by the applied voltage. This optic signal is transmitted to the PIN detector and converted to an electric signal which is processed by the electronic circuit and 8098 single chip microcomputer the output voltage signal obtained is directly proportional to the applied voltage. This paper describes the principle the configuration and the performance parameters of the system. Test results are evaluated and discussed.

  16. Delayed expression of SAGs correlates with longevity in CMS wheat plants compared to its fertile plants.

    Science.gov (United States)

    Semwal, Vimal Kumar; Singh, Bhupinder; Khanna-Chopra, Renu

    2014-04-01

    Reproductive sinks regulate monocarpic senescence in crop plants. Monocarpic senescence was studied in wheat fertile (cv. HW 2041) and its isonuclear cytoplasmic male sterile (CMS) line. CMS plants exhibited slower rate of senescence accompanied by longer green leaf area duration and slower deceleration in chlorophyll, protein content, PN and rubisco content coupled with lower protease activities than fertile (F) plants. CMS plants also exhibited lower ROS levels and less membrane damage than F plants. CMS plants maintained better antioxidant defense, less oxidative damage in chloroplast and higher transcript levels of both rbcL and rbcS genes during senescence than F plants. F plants exhibited early induction and higher expression of SAGs like serine and cysteine proteases, glutamine synthetases GS1 and GS2, WRKY53 transcription factor and decline in transcript levels of CAT1 and CAT2 genes than CMS plants. Hence, using genetically fertile and its CMS line of wheat it is confirmed that delayed senescence in the absence of reproductive sinks is linked with slower protein oxidation, rubisco degradation and delayed activation of SAGs. Better antioxidant defense in chloroplasts at later stages of senescence was able to mitigate the deleterious effects of ROS in CMS plants. We propose that delayed increase in ROS in cytoplasmic male sterile wheat plants resulted in delayed activation of WRKY53, SAGs and the associated biochemical changes than fertile plants.

  17. An Analytical Threshold Voltage Model of Fully Depleted (FD) Recessed-Source/Drain (Re-S/D) SOI MOSFETs with Back-Gate Control

    Science.gov (United States)

    Saramekala, Gopi Krishna; Tiwari, Pramod Kumar

    2016-10-01

    This paper presents an analytical threshold voltage model for back-gated fully depleted (FD), recessed-source drain silicon-on-insulator metal-oxide-semiconductor field-effect transistors (MOSFETs). Analytical surface potential models have been developed at front and back surfaces of the channel by solving the two-dimensional (2-D) Poisson's equation in the channel region with appropriate boundary conditions assuming a parabolic potential profile in the transverse direction of the channel. The strong inversion criterion is applied to the front surface potential as well as on the back one in order to find two separate threshold voltages for front and back channels of the device, respectively. The device threshold voltage has been assumed to be associated with the surface that offers a lower threshold voltage. The developed model was analyzed extensively for a variety of device geometry parameters like the oxide and silicon channel thicknesses, the thickness of the source/drain extension in the buried oxide, and the applied bias voltages with back-gate control. The proposed model has been validated by comparing the analytical results with numerical simulation data obtained from ATLAS™, a 2-D device simulator from SILVACO.

  18. New strategy for eliminating zero-sequence circulating current between parallel operating three-level NPC voltage source inverters

    DEFF Research Database (Denmark)

    Li, Kai; Dong, Zhenhua; Wang, Xiaodong

    2018-01-01

    A novel strategy based on a zero common mode voltage pulse-width modulation (ZCMV-PWM) technique and zero-sequence circulating current (ZSCC) feedback control is proposed in this study to eliminate ZSCCs between three-level neutral point clamped (NPC) voltage source inverters, with common AC and DC......, the ZCMV-PWM method is presented to reduce CMVs, and a simple electric circuit is adopted to control ZSCCs and neutral point potential. Finally, simulation and experiment are conducted to illustrate effectiveness of the proposed strategy. Results show that ZSCCs between paralleled inverters can...

  19. Dual voltage source inverter topology extending machine operating range

    NARCIS (Netherlands)

    Gerrits, T.; Wijnands, C.G.E.; Paulides, J.J.H.; Duarte, J.L.

    2012-01-01

    Field weakening operation of an electrical machine is a conventional method to extend the angular velocity range of a system above the peak output voltage of the inverter. A downside, however, is that an increased reactive current is required that creates losses but no output torque. A dual voltage

  20. Technological Aspects: High Voltage

    CERN Document Server

    Faircloth, D.C.

    2013-12-16

    This paper covers the theory and technological aspects of high-voltage design for ion sources. Electric field strengths are critical to understanding high-voltage breakdown. The equations governing electric fields and the techniques to solve them are discussed. The fundamental physics of high-voltage breakdown and electrical discharges are outlined. Different types of electrical discharges are catalogued and their behaviour in environments ranging from air to vacuum are detailed. The importance of surfaces is discussed. The principles of designing electrodes and insulators are introduced. The use of high-voltage platforms and their relation to system design are discussed. The use of commercially available high-voltage technology such as connectors, feedthroughs and cables are considered. Different power supply technologies and their procurement are briefly outlined. High-voltage safety, electric shocks and system design rules are covered.

  1. A Ratiometric Method for Johnson Noise Thermometry Using a Quantized Voltage Noise Source

    Science.gov (United States)

    Nam, S. W.; Benz, S. P.; Martinis, J. M.; Dresselhaus, P.; Tew, W. L.; White, D. R.

    2003-09-01

    Johnson Noise Thermometry (JNT) involves the measurement of the statistical variance of a fluctuating voltage across a resistor in thermal equilibrium. Modern digital techniques make it now possible to perform many functions required for JNT in highly efficient and predictable ways. We describe the operational characteristics of a prototype JNT system which uses digital signal processing for filtering, real-time spectral cross-correlation for noise power measurement, and a digitally synthesized Quantized Voltage Noise Source (QVNS) as an AC voltage reference. The QVNS emulates noise with a constant spectral density that is stable, programmable, and calculable in terms of known parameters using digital synthesis techniques. Changes in analog gain are accounted for by alternating the inputs between the Johnson noise sensor and the QVNS. The Johnson noise power at a known temperature is first balanced with a synthesized noise power from the QVNS. The process is then repeated by balancing the noise power from the same resistor at an unknown temperature. When the two noise power ratios are combined, a thermodynamic temperature is derived using the ratio of the two QVNS spectral densities. We present preliminary results where the ratio between the gallium triple point and the water triple point is used to demonstrate the accuracy of the measurement system with a standard uncertainty of 0.04 %.

  2. Case study and design of a Ride through device; Estudo de caso e projeto de um dispositivo Ridethrough

    Energy Technology Data Exchange (ETDEWEB)

    Conceicao, Claudio Alvares; Jesus, Edmundo Goncalves de [PETROBRAS, Betim, MG (Brazil). Refinaria Gabriel Passos - REGAP; Cardoso Filho, Braz de Jesus; Silva, Selenio Rocha [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil)

    2006-05-15

    The objective of the present study has been to identify equipment or systems sensitive to voltage sag, as well as to develop an appropriate solution for minimizing this sensibility. The presented proposal allows to the electric system of a petroleum refinery continues operating in spite of a momentary voltage sag, during an interval of enough time to support the phenomenon and to maintain the operational continuity.

  3. Computer code determination of tolerable accel current and voltage limits during startup of an 80 kV MFTF sustaining neutral beam source

    International Nuclear Information System (INIS)

    Mayhall, D.J.; Eckard, R.D.

    1979-01-01

    We have used a Lawrence Livermore Laboratory (LLL) version of the WOLF ion source extractor design computer code to determine tolerable accel current and voltage limits during startup of a prototype 80 kV Mirror Fusion Test Facility (MFTF) sustaining neutral beam source. Arc current limits are also estimated. The source extractor has gaps of 0.236, 0.721, and 0.155 cm. The effective ion mass is 2.77 AMU. The measured optimum accel current density is 0.266 A/cm 2 . The gradient grid electrode runs at 5/6 V/sub a/ (accel voltage). The suppressor electrode voltage is zero for V/sub a/ < 3 kV and -3 kV for V/sub a/ greater than or equal to 3 kV. The accel current density for optimum beam divergence is obtained for 1 less than or equal to V/sub a/ less than or equal to 80 kV, as are the beam divergence and emittance

  4. Novel design of high voltage pulse source for efficient dielectric barrier discharge generation by using silicon diodes for alternating current

    Science.gov (United States)

    Truong, Hoa Thi; Hayashi, Misaki; Uesugi, Yoshihiko; Tanaka, Yasunori; Ishijima, Tatsuo

    2017-06-01

    This work focuses on design, construction, and optimization of configuration of a novel high voltage pulse power source for large-scale dielectric barrier discharge (DBD) generation. The pulses were generated by using the high-speed switching characteristic of an inexpensive device called silicon diodes for alternating current and the self-terminated characteristic of DBD. The operation started to be powered by a primary DC low voltage power supply flexibly equipped with a commercial DC power supply, or a battery, or DC output of an independent photovoltaic system without transformer employment. This flexible connection to different types of primary power supply could provide a promising solution for the application of DBD, especially in the area without power grid connection. The simple modular structure, non-control requirement, transformer elimination, and a minimum number of levels in voltage conversion could lead to a reduction in size, weight, simple maintenance, low cost of installation, and high scalability of a DBD generator. The performance of this pulse source has been validated by a load of resistor. A good agreement between theoretically estimated and experimentally measured responses has been achieved. The pulse source has also been successfully applied for an efficient DBD plasma generation.

  5. Semi-Active Control of Three-Dimensional Vibrations of an Inclined Sag Cable with Magnetorheological Dampers

    DEFF Research Database (Denmark)

    Zhou, Q.; Nielsen, Søren R.K.; Qu, W. L.

    2006-01-01

    Three-dimensional semi-active vibration control of an inclined sag cable with discrete magnetorheological (MR) dampers is investigated in this paper using the finite difference method (FDM). A modified Dahl model is used to describe the dynamic property of MR damper. The nonlinear equations...

  6. Low-Cost Open-Source Voltage and Current Monitor for Gas Metal Arc Weld 3D Printing

    OpenAIRE

    Pinar, A.; Wijnen, B.; Anzalone, G. C.; Havens, T. C.; Sanders, P. G.; Pearce, J. M.

    2015-01-01

    Arduino open-source microcontrollers are well known in sensor applications for scientific equipment and for controlling RepRap 3D printers. Recently low-cost open-source gas metal arc weld (GMAW) RepRap 3D printers have been developed. The entry-level welders used have minimal controls and therefore lack any real-time measurement of welder voltage or current. The preliminary work on process optimization of GMAW 3D printers requires a low-cost sensor and data logger system to measure welder cu...

  7. An analysis of natural gas exploration potential in the Qiongdongnan Basin by use of the theory of “joint control of source rocks and geothermal heat”

    Directory of Open Access Journals (Sweden)

    Zhang Gongcheng

    2014-10-01

    Full Text Available The Oligocene Yacheng Fm contains the most important source rocks that have been confirmed by exploratory wells in the Qiongdongnan Basin. The efficiency of these source rocks is the key to the breakthrough in natural gas exploration in the study area. This paper analyzes the hydrocarbon potential of each sag in this basin from the perspective of control of both source rocks and geothermal heat. Two types of source rocks occur in the Yacheng Fm, namely mudstone of transitional facies and mudstone of neritic facies. Both of them are dominated by a kerogen of type-III, followed by type-II. Their organic matter abundances are controlled by the amount of continental clastic input. The mudstone of transitional facies is commonly higher in organic matter abundance, while that of neritic facies is lower. The coal-measure source rocks of transitional facies were mainly formed in such environments as delta plains, coastal plains and barrier tidal flat-marshes. Due to the control of Cenozoic lithosphere extension and influence of neotectonism, the geothermal gradient, terrestrial heat flow value (HFV and level of thermal evolution are generally high in deep water. The hot setting not only determines the predominance of gas generation in the deep-water sags, but can promote the shallow-buried source rocks in shallow water into oil window to generate oil. In addition to promoting the hydrocarbon generation of source rocks, the high geothermal and high heat flow value can also speed up the cracking of residual hydrocarbons, thus enhancing hydrocarbon generation efficiency and capacity. According to the theory of joint control of source quality and geothermal heat on hydrocarbon generation, we comprehensively evaluate and rank the exploration potentials of major sags in the Qiongdongnan Basin. These sags are divided into 3 types, of which type-I sags including Yanan, Lingshui, Baodao, Ledong and Huaguang are the highest in hydrocarbon exploration potential.

  8. Technological Aspects: High Voltage

    International Nuclear Information System (INIS)

    Faircloth, D C

    2013-01-01

    This paper covers the theory and technological aspects of high-voltage design for ion sources. Electric field strengths are critical to understanding high-voltage breakdown. The equations governing electric fields and the techniques to solve them are discussed. The fundamental physics of high-voltage breakdown and electrical discharges are outlined. Different types of electrical discharges are catalogued and their behaviour in environments ranging from air to vacuum are detailed. The importance of surfaces is discussed. The principles of designing electrodes and insulators are introduced. The use of high-voltage platforms and their relation to system design are discussed. The use of commercially available high-voltage technology such as connectors, feedthroughs and cables are considered. Different power supply technologies and their procurement are briefly outlined. High-voltage safety, electric shocks and system design rules are covered. (author)

  9. Control Method Stretches Suspensions by Measuring the Sag of Strands in Cable-Stayed Bridges

    Science.gov (United States)

    Bętkowski, Piotr

    2017-10-01

    In the article is described the method that allows on evaluation and validation of measurement correctness of dynamometers (strain gauges, tension meters) used in systems of suspensions. Control of monitoring devices such as dynamometers is recommended in inspections of suspension bridges. Control device (dynamometer) works with an anchor, and the degree of this cooperation could have a decisive impact on the correctness of the results. Method, which determines the stress in the strand (cable), depending on the sag of stayed cable, is described. This method can be used to control the accuracy of measuring devices directly on the bridge. By measuring the strand sag, it is possible to obtain information about the strength (force) which occurred in the suspension cable. Digital camera is used for the measurement of cable sag. Control measurement should be made independently from the controlled parameter but should verify this parameter directly (it is the best situation). In many cases in practice the controlled parameter is not designation by direct measurement, but the calculations, i.e. relation measured others parameters, as in the method described in the article. In such cases occurred the problem of overlapping error of measurement of intermediate parameters (data) and the evaluation of the reliability of the results. Method of control calculations made in relation to installed in the bridge measuring devices is doubtful without procedure of uncertainty estimation. Such an assessment of the accuracy can be performed using the interval numbers. With the interval numbers are possible the analysis of parametric relationship accuracy of the designation of individual parameters and uncertainty of results. Method of measurements, relations and analytical formulas, and numerical example can be found in the text of the article.

  10. Improving Energy Efficiency Via Optimized Charge Motion and Slurry Flow in Plant Scale Sag Mills

    Energy Technology Data Exchange (ETDEWEB)

    Raj K. Rajamani

    2006-07-21

    A research team from the University of Utah is working to make inroads into saving energy in these SAG mills. In 2003, Industries of the Future Program of the Department of Energy tasked the University of Utah team to build a partnership between the University and the mining industry for the specific purpose of reducing energy consumption in SAG mills. A partnership was formed with Cortez Gold Mines, Outokumpu Technology, Kennecott Utah Copper Corporation, and Process Engineering Resources Inc. At Cortez Gold Operations the shell and pulp lifters of the semiautogenous grinding mill was redesigned. The redesigned shell lifter has been in operation for over three years and the redesigned pulp lifter has been in operation for over nine months now. This report summarizes the dramatic reductions in energy consumption. Even though the energy reductions are very large, it is safe to say that a 20% minimum reduction would be achieved in any future installations of this technology.

  11. PC-based control of a high-voltage injector

    International Nuclear Information System (INIS)

    Constantin, F.

    1998-01-01

    The stability of high voltage injectors is one of the major problems in any accelerator system. Most of the troubles encountered in the normal operation of an accelerator are connected with the ion source and associated high voltage platforms, regardless of the source or high voltage generator type. The quality of the ion beam injected in the accelerator strongly depends on the power supplies used in the injector and on the ability to control the non-electrical parameters (gas-flow, temperature, etc.). A wide used method in controlling is based on optical links between high-voltage platform and computer, the adjustments being more or less automated. Although the method mentioned above can be still useful in injector control, a different approach is presented in this work, i.e., the computer itself is placed inside the high-voltage terminal. Only one optical link is still necessary to connect this computer with an user-friendly host at ground potential. Requirements: - varying and monitoring the filament current; - gas flow control in the ion source; - reading the vacuum values; - current and voltage control for the anodic, magnet, extraction, suppression and lens' sources. Even in the high voltage terminal there are compartments with different voltages regardless the floating ground. In our injector the extraction voltage is applied on the top of the ion source including the filament and the anodic voltage. The extraction voltage is of maximum 30 kV. In this situation a second optical link is required to transfer the control for the anodic and magnet source power supply assuming the dedicated computer on the floating ground. One PC is placed inside the high voltage terminal and one PC outside the injector. The optical link (more precisely two optical wires) connects the serial ports. The inside computer is equipped with two multipurpose ADC/DAC and digital I/O card. They permit to read or output DC levels ranging between 0 to 10 volts or TTL signals. The filament

  12. Mitigation of grid-current distortion for LCL-filtered grid-connected voltage-source inverter with inverter-side current control

    DEFF Research Database (Denmark)

    Xin, Zhen; Mattavelli, Paolo; Yao, WenLi

    2017-01-01

    Due to the low inductance of an LCL-filter, the grid current generated by an LCL-filtered Voltage Source Inverter (VSI) is sensitive to low-order grid-voltage harmonics. This issue is especially tough for the control system with Inverter Current Feedback (ICF), because the grid-current harmonics...... can freely flow into the filter capacitor without control. To cope with this issue, this paper develops an approach for the ICF control system to suppress the grid-current harmonics without adding extra sensors. The proposed method applies harmonic controllers and feedforward scheme simultaneously...

  13. Voltage optimal regulation of distribution power network with a source of dispersed generation owned by either one or several owners

    Directory of Open Access Journals (Sweden)

    Олександр Станиславович Яндульський

    2015-11-01

    Full Text Available The criteria of optimal voltage regulation in the electrical distribution network (EDN with a source of dispersed generation (SDG were formulated, if they belong to either one or different owners, taking into account the peculiarities of voltage regulation by means of the SDG and the OLTC system of the transformer. It was found out that under the conditions of economic unprofitability of voltage regulation, in accordance with the above criteria, the owners should take up coordinated work – the general objective function of voltage regulation to improve the effectiveness of regulation and achieve cost-effectiveness. The criteria of optimal voltage regulation if EDN and SDG belong to one owner were formulated. If their work becomes coordinated it is necessary to know exactly which transformer must be regulated; so a transformer with OLTC system should be chosen. Selection sequence is based on the calculation of the sensitivity of the voltage at the nodes within SDG with respect to OLTC position. The proposed OLTC system and SDG coordinated work makes it possible to increase the effectiveness of voltage regulation in the EDN with SDG under different conditions of ownership and increase the economic profitability of regulation

  14. Effect of Advanced Plasma Source bias voltage on properties of HfO2 films prepared by plasma ion assisted electron evaporation from metal hafnium

    International Nuclear Information System (INIS)

    Zhu, Meiping; Yi, Kui; Arhilger, Detlef; Qi, Hongji; Shao, Jianda

    2013-01-01

    HfO 2 films, using metal hafnium as starting material, are deposited by plasma-ion assisted electron evaporation with different Advanced Plasma Source (APS) bias voltages. The refractive index and extinction coefficient are calculated, the chemical state and composition, as well as the stress and aging behavior is investigated. Laser induced damage threshold (LIDT) and damage mechanism are also evaluated and discussed. Optical, structural, mechanical and laser induced damage properties of HfO 2 films are found to be sensitive to APS bias voltage. The film stress can be tuned by varying the APS bias voltage. Damage morphologies indicate the LIDT of the HfO 2 films at 1064 nm and 532 nm are dominated by the nodular-defect density in coatings, while the 355 nm LIDT is dominated by the film absorption. HfO 2 films with higher 1064 nm LIDT than samples evaporated from hafnia are achieved with bias voltage of 100 V. - Highlights: • HfO 2 films are evaporated with different Advanced Plasma Source (APS) bias voltages. • Properties of HfO 2 films are sensitive to APS bias voltage. • With a bias voltage of 100 V, HfO 2 coatings without any stress can be achieved. • Higher 1064 nm laser induced damage threshold is achieved at a bias voltage of 100 V

  15. Distributed stability control using intelligent voltage-margin relay

    Energy Technology Data Exchange (ETDEWEB)

    Wiszniewski, A.; Rebizant, W. [Wroclaw Univ. of Technology (Poland); Klimek, A. [Powertech Labs Inc., Surrey, BC (Canada)

    2010-07-01

    This paper presented an intelligent relay that operates if the load to source impedance ratio decreases to a level that is dangerously close to the stability limit, which leads to power system blackouts. The intelligent voltage-margin/difference relay installed at receiving substations automatically initiates action if the voltage stability margin drops to a dangerously low level. The relay decides if the tap changing devices are to be blocked and if under-voltage load shedding should be initiated, thereby mitigating an evolving instability. The intelligent relay has two levels of operation. At the first stage, which corresponds to the higher load to source impedance ratio, the relay initiates blocking of the tap changer. At the second stage, corresponding to the lower source to load impedance ratio, load shedding is initiated. The relay operates when the load to source impedance ratio reaches a certain predetermined level, but it does not depend either on the level of the source voltage or on the difference of source and load impedance phase angles. The algorithm for the relay is relatively simple and uses only locally available signals. Consequently, the transformer is well controlled to eliminate the cases of voltage instability. 6 refs., 7 figs.

  16. Current-voltage model of LED light sources

    DEFF Research Database (Denmark)

    Beczkowski, Szymon; Munk-Nielsen, Stig

    2012-01-01

    Amplitude modulation is rarely used for dimming light-emitting diodes in polychromatic luminaires due to big color shifts caused by varying magnitude of LED driving current and nonlinear relationship between intensity of a diode and driving current. Current-voltage empirical model of light...

  17. Electrical Power Quality - What's Behind the Outlet?

    Science.gov (United States)

    Baird, William H.; Secrest, Jeffery; Padgett, Clifford

    2017-09-01

    Although we may consider the power outlets in our homes to be nearly ideal voltage sources, a variety of influences in and around the home can cause departures from the nominal 60 Hz, 110-120 V root-mean-square (rms) of the North American grid. Even without instrumentation, we can see that a large motor starting from rest can be sufficient to cause lights to dim momentarily (voltage sag). This dimming is due to the inrush current drawn by a stationary motor, which may be several times the current drawn at operating speed. We prepared a voltage monitoring system using a voltage divider, the construction details of which we omit in the interest of safety.

  18. The effect of tectonic evolution on lacustrine syn-rift sediment patters in Qikou Sag, Bohaiwan Basin, eastern China

    Science.gov (United States)

    Liao, Y.; Wang, H.; Xu, W.

    2013-12-01

    investigate the degree of tectonic control on subaqueous sediment transportation and dispersal. Specific attention is paid to deposits close to boundary faults-Gangxi fault, Gangdong fault and Binhai fault and associated relay ramp. Our studies show that significant amount of sediments were deposited on the basin floor close to boundary faults hanging-wall, which were derived from Cangxian uplift and might have originated from channel overspill or flow shedding across the faults. However, minor deposits occurred adjacent to and at the foot of relay ramp, suggesting an influence of these topography features on sediment routing, with the intrabasinal structural high-Beidagang buried hill acting as an additional sediment source. Therefore, the substantial differences between subaerial and subaqueous systems may influence the role of relay ramps in controlling the sediment routes and deposition in Qikou Sag. The attempt to depict subaqueous syn-rift sediment dispersal and relate them with relay ramps is needed to consider the interplay of various factors such as sediment provenience, tectonic activity, ramp geometry, and base level fluctuations in the future investigation.

  19. Analytical and semi-analytical formalism for the voltage and the current sources of a superconducting cavity under dynamic detuning

    CERN Document Server

    Doleans, M

    2003-01-01

    Elliptical superconducting radio frequency (SRF) cavities are sensitive to frequency detuning because they have a high Q value in comparison with normal conducting cavities and weak mechanical properties. Radiation pressure on the cavity walls, microphonics, and tuning system are possible sources of dynamic detuning during SRF cavity-pulsed operation. A general analytic relation between the cavity voltage, the dynamic detuning function, and the RF control function is developed. This expression for the voltage envelope in a cavity under dynamic detuning and dynamic RF controls is analytically expressed through an integral formulation. A semi-analytical scheme is derived to calculate the voltage behavior in any practical case. Examples of voltage envelope behavior for different cases of dynamic detuning and RF control functions are shown. The RF control function for a cavity under dynamic detuning is also investigated and as an application various filling schemes are presented.

  20. Cytokine Gene Expression in Response to SnSAG1 in Horses with Equine Protozoal Myeloencephalitis

    Science.gov (United States)

    Spencer, Jennifer A.; Deinnocentes, Patricia; Moyana, Edith M.; Guarino, Anthony J.; Ellison, Siobhan E.; Bird, R. Curtis; Blagburn, Byron L.

    2005-01-01

    Equine protozoal myeloencephalitis (EPM) is a neurologic syndrome seen in horses from the Americas and is mainly caused by Sarcocystis neurona. Recently, a 29-kDa surface antigen from S. neurona merozoites was identified as being highly immunodominant on a Western blot. This antigen has been sequenced and cloned, and the expressed protein has been named SnSAG1. In a previous study, cell-mediated immune responses to SnSAG1 were shown to be statistically significantly reduced in horses with EPM in comparison to EPM-negative control horses. It therefore appears as though the parasite is able to induce immunosuppression towards parasite-derived antigens as parasite-specific responses are decreased. Isolated peripheral blood lymphocytes from 21 EPM (cerebrospinal fluid [CSF] Western blot)-negative horses with no clinical signs and 21 horses with clinical signs of EPM (CSF Western blot positive) were cocultured with SnSAG1 for 48 and 72 h, and the effect on cytokine production was investigated by means of reverse transcriptase PCR. Cytokines assayed include gamma interferon (IFN-γ), tumor necrosis factor alpha, interleukin (IL)-2, IL-4, and IL-6. β-Actin was used as the housekeeping gene. A Wilcoxon signed-rank test of the findings indicated that there was a statistically significant decrease in IFN-γ production after 48 h in culture for samples from horses with clinical disease. There was also a statistically significant increase in IL-4 production after 72 h in culture for samples from horses with EPM. These results further support the notion that this parasite is able to subvert the immune system in horses with clinical disease. PMID:15879026

  1. Survey of high-voltage pulse technology suitable for large-scale plasma source ion implantation processes

    International Nuclear Information System (INIS)

    Reass, W.A.

    1994-01-01

    Many new plasma processes ideas are finding their way from the research lab to the manufacturing plant floor. These require high voltage (HV) pulse power equipment, which must be optimized for application, system efficiency, and reliability. Although no single HV pulse technology is suitable for all plasma processes, various classes of high voltage pulsers may offer a greater versatility and economy to the manufacturer. Technology developed for existing radar and particle accelerator modulator power systems can be utilized to develop a modern large scale plasma source ion implantation (PSII) system. The HV pulse networks can be broadly defined by two classes of systems, those that generate the voltage directly, and those that use some type of pulse forming network and step-up transformer. This article will examine these HV pulse technologies and discuss their applicability to the specific PSII process. Typical systems that will be reviewed will include high power solid state, hard tube systems such as crossed-field ''hollow beam'' switch tubes and planar tetrodes, and ''soft'' tube systems with crossatrons and thyratrons. Results will be tabulated and suggestions provided for a particular PSII process

  2. Design issues of the High Voltage platform and feedthrough for the ITER NBI Ion Source

    International Nuclear Information System (INIS)

    Boldrin, M.; Palma, M. Dalla; Milani, F.

    2009-01-01

    In the ITER heating Neutral Beam Injector (NBI), a High Voltage air-insulated platform (named High Voltage Deck, HVD) will be installed to host the Ion Source and Extractor Power supply system and associated diagnostics referred to -1 MV DC potential. All power and control cables are routed from the HVD via a feedthrough (HV bushing) to the gas insulated transmission line which feeds the Injector. The paper focuses on insulation and mechanical issues for both HVD and HV bushing which are very special components, far from the present industrial standards as far as voltage (-1 MV DC) and dimensions are concerned. For this purpose, a preliminary design of the HVD has been carried out as concerns the mechanical structure and external shield. Then, the structure has been verified with a seismic analysis applying the seismic load excitation specified for the ITER construction site (Cadarache) and carrying out verifications according to relevant international standards. As regards the HV bushing design, proposals for the complex inner conductor structure and for interfaces to the HVD and transmission line are outlined; alternative installation layouts (aside or underneath the HVD) are compared from both mechanical and electrical points of view.

  3. Radio frequency glow discharge source with integrated voltage and current probes used for evaluation of discharge parameters

    International Nuclear Information System (INIS)

    Wilken, L.; Hoffmann, V.; Wetzig, K.

    2006-01-01

    A radio frequency (rf) Grimm-type glow discharge source for the chemical analysis of solid samples, with integrated voltage and current probes, was developed. All elements of a plasma equivalent circuit are determined from the measured current-voltage characteristics. The procedure is based on the independent evaluation of the ion current and electron current region. The physical meaning of the parameters is investigated by comparisons with measurements from dc glow discharges. We found that the reduced rf current of the powered electrode is comparable to the reduced current in dc discharges. A formula is developed that corrects the reduced current due to gas heating. The sheath thickness at the powered rf electrode is evaluated and is between 75 and 1100 μm. The voltage of the bulk plasma is in the range 2-15 V, and the resistance is between 30 and 400 Ω. The bulk plasma consumes about 3% of the total power, and the reduced voltage is comparable to the reduced electrical field in the positive column of direct current discharges. The sheath voltage at the grounded electrode is in the range 25-100 V, the capacities are between 10 and 400 pF, and the resistances are in the range 100 Ω-5000 Ω. We also found invariants for the evaluated sheath parameters

  4. Core evidence of paleoseismic events in Paleogene deposits of the Shulu Sag in the Bohai Bay Basin, east China, and their petroleum geologic significance

    Science.gov (United States)

    Zheng, Lijing; Jiang, Zaixing; Liu, Hui; Kong, Xiangxin; Li, Haipeng; Jiang, Xiaolong

    2015-10-01

    The Shulu Sag, located in the southwestern corner of the Jizhong Depression, Bohai Bay Basin of east China, is a NE-SW trending, elongate Cenozoic half-graben basin. The lowermost part of the third member of the Shahejie Formation in this basin is characterized by continental rudstone and calcilutite to calcisiltite facies. Based on core observation and regional geologic analysis, seismites are recognized in these lacustrine deposits, which include soft-sediment deformation structures (sedimentary dikes, hydraulic shattering, diapir structures, convolute lamination, load-flame structures, ball-and-pillow structures, loop bedding, and subsidence structures), synsedimentary faults, and seismoturbidites. In addition, mixed-source rudstones, consisting of the Paleozoic carbonate clasts and in situ calcilutite clasts in the lowermost submember of Shahejie 3, appear in the seismites, suggesting an earthquake origin. A complete representative vertical sequence in the lowermost part of the third member found in well ST1H located in the central part of the Shulu Sag shows, from the base to the top: underlying undeformed layers, synsedimentary faults, liquefied carbonate rocks, allogenetic seismoturbidites, and overlying undeformed layers. Seismites are widely distributed around this well and there are multiple sets of stacked seismites separated by undeformed sediment. The nearby NW-trending Taijiazhuang fault whose fault growth index is from 1.1 to 1.8 and the NNE-trending Xinhe fault with a fault growth index of 1.3-1.9 may be the source of the instability to create the seismites. These deformed sedimentary layers are favorable for the accumulation of oil and gas; for example, sedimentary dikes can cut through many layers and serve as conduits for fluid migration. Sedimentary faults and fractures induced by earthquakes can act as oil and gas migration channels or store petroleum products as well. Seismoturbidites and mixed-source rudstones are excellent reservoirs due to

  5. The bacteria binding glycoprotein salivary agglutinin (SAG/gp340) activates complement via the lectin pathway

    NARCIS (Netherlands)

    Leito, Jelani T. D.; Ligtenberg, Antoon J. M.; van Houdt, Michel; van den Berg, Timo K.; Wouters, Diana

    2011-01-01

    Salivary agglutinin (SAG), also known as gp-340 and Deleted in Malignant Brain Tumours 1, is a glycoprotein that is present in tears, lung fluid and mucosal surfaces along the gastrointestinal tract. It is encoded by the Deleted in Malignant Brain Tumours 1 gene, a member of the Scavenger Receptor

  6. Voltage Quality of Grid Connected Wind Turbines

    DEFF Research Database (Denmark)

    Chen, Zhe; Blaabjerg, Frede; Sun, Tao

    2004-01-01

    Grid connected wind turbines may cause quality problems, such as voltage variation and flicker. This paper discusses the voltage variation and flicker emission of grid connected wind turbines with doubly-fed induction generators. A method to compensate flicker by using a voltage source converter...

  7. The Application of Auto-Disturbance Rejection Control Optimized by Least Squares Support Vector Machines Method and Time-Frequency Representation in Voltage Source Converter-High Voltage Direct Current System.

    Science.gov (United States)

    Liu, Ying-Pei; Liang, Hai-Ping; Gao, Zhong-Ke

    2015-01-01

    In order to improve the performance of voltage source converter-high voltage direct current (VSC-HVDC) system, we propose an improved auto-disturbance rejection control (ADRC) method based on least squares support vector machines (LSSVM) in the rectifier side. Firstly, we deduce the high frequency transient mathematical model of VSC-HVDC system. Then we investigate the ADRC and LSSVM principles. We ignore the tracking differentiator in the ADRC controller aiming to improve the system dynamic response speed. On this basis, we derive the mathematical model of ADRC controller optimized by LSSVM for direct current voltage loop. Finally we carry out simulations to verify the feasibility and effectiveness of our proposed control method. In addition, we employ the time-frequency representation methods, i.e., Wigner-Ville distribution (WVD) and adaptive optimal kernel (AOK) time-frequency representation, to demonstrate our proposed method performs better than the traditional method from the perspective of energy distribution in time and frequency plane.

  8. The Application of Auto-Disturbance Rejection Control Optimized by Least Squares Support Vector Machines Method and Time-Frequency Representation in Voltage Source Converter-High Voltage Direct Current System.

    Directory of Open Access Journals (Sweden)

    Ying-Pei Liu

    Full Text Available In order to improve the performance of voltage source converter-high voltage direct current (VSC-HVDC system, we propose an improved auto-disturbance rejection control (ADRC method based on least squares support vector machines (LSSVM in the rectifier side. Firstly, we deduce the high frequency transient mathematical model of VSC-HVDC system. Then we investigate the ADRC and LSSVM principles. We ignore the tracking differentiator in the ADRC controller aiming to improve the system dynamic response speed. On this basis, we derive the mathematical model of ADRC controller optimized by LSSVM for direct current voltage loop. Finally we carry out simulations to verify the feasibility and effectiveness of our proposed control method. In addition, we employ the time-frequency representation methods, i.e., Wigner-Ville distribution (WVD and adaptive optimal kernel (AOK time-frequency representation, to demonstrate our proposed method performs better than the traditional method from the perspective of energy distribution in time and frequency plane.

  9. Possibilities by using a self-commutated voltage source inverter connected to a weak grid in wind parks

    Energy Technology Data Exchange (ETDEWEB)

    Svensson, Jan [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Electric Power Engineering

    1996-12-01

    In this paper the hybrid wind farm connected to a weak grid is investigated. By combining different electrical wind power plant systems a cost-efficient solution is obtained. The point of common connection voltage level can be controlled by injecting reactive power from a phase-compensating capacitor battery and a voltage source inverter (VSI). If the short-circuit impedance ratio is lower than 1, the demanded reactive power injection to keep the voltage at nominal level is unrealistic. For short-circuit impedance ratios of 2 or higher the demanded reactive power level is acceptable. When using both induction generators and thyristor inverters the reactive power injector VSI size should be about 0.2 pu. If the hybrid farm consists of THYs, IGs and VSIs and the active power is equally shared between the systems, the VSI had to be scaled up by 5% to handle both active and reactive power. 7 refs, 10 figs, 2 tabs

  10. A Circulating Current Suppression Method for Parallel Connected Voltage-Source-Inverters (VSI) with Common DC and AC Buses

    DEFF Research Database (Denmark)

    Wei, Baoze; Guerrero, Josep M.; Quintero, Juan Carlos Vasquez

    2016-01-01

    This paper describes a theoretical with experiment study on a control strategy for the parallel operation of threephase voltage source inverters (VSI), to be applied to uninterruptible power systems (UPS). A circulating current suppression strategy for parallel VSIs is proposed in this paper based...... on circulating current control loops used to modify the reference currents by compensating the error currents among parallel inverters. Both of the cross and zero-sequence circulating currents are considered. The proposed method is coordinated together with droop and virtual impedance control. In this paper......, droop control is used to generate the reference voltage of each inverter, and the virtual impedance is used to fix the output impedance of the inverters. In addition, a secondary control is used in order to recover the voltage deviation caused by the virtual impedance. And the auxiliary current control...

  11. Modular high voltage power supply for chemical analysis

    Science.gov (United States)

    Stamps, James F [Livermore, CA; Yee, Daniel D [Dublin, CA

    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.

  12. Removal of Direct Current Link Harmonic Ripple in Single Phase Voltage Source Inverter Systems Using Supercapacitors

    Science.gov (United States)

    2016-09-01

    Khaligh, “Optimization of sizing and battery cycle life in battery/ultracapacitor hybrid energy storage systems for electric vehicle applications...depth cycling operation in photovoltaic system ,” in 22nd International Conference “Mixed Design of Integrated Circuits and Systems ,” Toruń, Poland...CURRENT LINK HARMONIC RIPPLE IN SINGLE-PHASE VOLTAGE SOURCE INVERTER SYSTEMS USING SUPERCAPACITORS by Gabriel D. Hernandez September 2016

  13. Analysis of Peak-to-Peak Current Ripple Amplitude in Seven-Phase PWM Voltage Source Inverters

    Directory of Open Access Journals (Sweden)

    Gabriele Grandi

    2013-08-01

    Full Text Available Multiphase systems are nowadays considered for various industrial applications. Numerous pulse width modulation (PWM schemes for multiphase voltage source inverters with sinusoidal outputs have been developed, but no detailed analysis of the impact of these modulation schemes on the output peak-to-peak current ripple amplitude has been reported. Determination of current ripple in multiphase PWM voltage source inverters is important for both design and control purposes. This paper gives the complete analysis of the peak-to-peak current ripple distribution over a fundamental period for multiphase inverters, with particular reference to seven-phase VSIs. In particular, peak-to-peak current ripple amplitude is analytically determined as a function of the modulation index, and a simplified expression to get its maximum value is carried out. Although reference is made to the centered symmetrical PWM, being the most simple and effective solution to maximize the DC bus utilization, leading to a nearly-optimal modulation to minimize the RMS of the current ripple, the analysis can be readily extended to either discontinuous or asymmetrical modulations, both carrier-based and space vector PWM. A similar approach can be usefully applied to any phase number. The analytical developments for all different sub-cases are verified by numerical simulations.

  14. Hybrid HVDC (H2VDC System Using Current and Voltage Source Converters

    Directory of Open Access Journals (Sweden)

    José Rafael Lebre

    2018-05-01

    Full Text Available This paper presents an analysis of a new high voltage DC (HVDC transmission system, which is based on current and voltage source converters (CSC and VSC in the same circuit. This proposed topology is composed of one CSC (rectifier and one or more VSCs (inverters connected through an overhead transmission line in a multiterminal configuration. The main purpose of this Hybrid HVDC (H2VDC, as it was designed, is putting together the best benefits of both types of converters in the same circuit: no commutation failure and system’s black start capability in the VSC side, high power converter capability and low cost at the rectifier side, etc. A monopole of the H2VDC system with one CSC and two VSCs—here, the VSC is the Modular Multilevel Converter (MMC considered with full-bridge submodules—in multiterminal configuration is studied. The study includes theoretical analyses, development of the CSC and VSCs control philosophies and simulations. The H2VDC system’s behavior is analyzed by computational simulations considering steady-state operation and short-circuit conditions at the AC and DC side. The obtained results and conclusions show a promising system for very high-power multiterminal HVDC transmission.

  15. Comparison of the effects of SAG-M and whole-blood transfusions on postoperative suppression of delayed hypersensitivity

    DEFF Research Database (Denmark)

    Nielsen, Hans Jørgen; Hammer, J H; Moesgaard, F

    1991-01-01

    The influence of perioperative whole-blood transfusion and transfusion with erythrocyte suspension (SAG-M blood) on postoperative depression of cell-mediated immunity (CMI) was investigated in 67 patients who underwent elective resection for colorectal cancer. Cell-mediated immunity was assessed...

  16. Acute viral hepatitis in adults. Comparison of the radioimmunoassay and counterimmunoelectrophoresis methods of detecting HB/sub s/Ag

    International Nuclear Information System (INIS)

    Wenzel, R.P.; Teates, C.D.; Galapon, Q.; Barczak, R.; Ling, C.M.; Overby, L.R.

    1975-01-01

    The radioimmunoassay (RIA) and counterimmunoelectrophoretic (CIE) methods were compared in detecting hepatitis B antigen (HB/sub s/Ag) in 407 acute and 336 convalescent sera of adults with viral hepatitis. The CIE method demonstrated that 41 percent of acute and 28 percent of 14- to 17-day serum specimens were HB/sub s/Ag-positive. The RIA method demonstrated seropositivity in 60 percent of acute and 56 percent of convalescent specimens (P less than .001). Eighty-four percent of coded specimens initially positive for HB/sub s/Ag by RIA were found to have subtype antigenic determinants d or y; 92 percent of the HB/sub s/Ag-negative controls were negative for subtype antigens, confirming the specificity of the RIA test. RIA subtyping data corroborated earlier work with immunodiffusion techniques. (U.S.)

  17. Performance Analysis of a Voltage Source Converter (VSC based HVDC Transmission System under Faulted Conditions

    Directory of Open Access Journals (Sweden)

    Amiri RABIE

    2009-12-01

    Full Text Available Voltage Source Converter (VSC based HVDC transmission technology hasbeen selected as the basis for several recent projects due to its controllability,compact modular design, ease of system interface, and low environmentalimpact. This paper investigates the dynamic performance of a 200MW,±100kV VSC-HVDC transmission system under some faulted conditionsusing MATLAB/Simulink. Simulation results confirm the satisfactoryperformance of the proposed system under active and reactive powervariations and fault conditions.

  18. Voltage harmonic elimination with RLC based interface smoothing filter

    International Nuclear Information System (INIS)

    Chandrasekaran, K; Ramachandaramurthy, V K

    2015-01-01

    A method is proposed for designing a Dynamic Voltage Restorer (DVR) with RLC interface smoothing filter. The RLC filter connected between the IGBT based Voltage Source Inverter (VSI) is attempted to eliminate voltage harmonics in the busbar voltage and switching harmonics from VSI by producing a PWM controlled harmonic voltage. In this method, the DVR or series active filter produces PWM voltage that cancels the existing harmonic voltage due to any harmonic voltage source. The proposed method is valid for any distorted busbar voltage. The operating VSI handles no active power but only harmonic power. The DVR is able to suppress the lower order switching harmonics generated by the IGBT based VSI. Good dynamic and transient results obtained. The Total Harmonic Distortion (THD) is minimized to zero at the sensitive load end. Digital simulations are carried out using PSCAD/EMTDC to validate the performance of RLC filter. Simulated results are presented. (paper)

  19. Time isolation high-voltage impulse generator

    International Nuclear Information System (INIS)

    Chodorow, A.M.

    1975-01-01

    Lewis' high-voltage impulse generator is analyzed in greater detail, demonstrating that voltage between adjacent nodes can be equalized by proper selection of parasitic impedances. This permits improved TEM mode propagation to a matched load, with more faithful source waveform preservation

  20. Design and test of component circuits of an integrated quantum voltage noise source for Johnson noise thermometry

    International Nuclear Information System (INIS)

    Yamada, Takahiro; Maezawa, Masaaki; Urano, Chiharu

    2015-01-01

    Highlights: • We demonstrated RSFQ digital components of a new quantum voltage noise source. • A pseudo-random number generator and variable pulse number multiplier are designed. • Fabrication process is based on four Nb wiring layers and Nb/AlOx/Nb junctions. • The circuits successfully operated with wide dc bias current margins, 80–120%. - Abstract: We present design and testing of a pseudo-random number generator (PRNG) and a variable pulse number multiplier (VPNM) which are digital circuit subsystems in an integrated quantum voltage noise source for Jonson noise thermometry. Well-defined, calculable pseudo-random patterns of single flux quantum pulses are synthesized with the PRNG and multiplied digitally with the VPNM. The circuit implementation on rapid single flux quantum technology required practical circuit scales and bias currents, 279 junctions and 33 mA for the PRNG, and 1677 junctions and 218 mA for the VPNM. We confirmed the circuit operation with sufficiently wide margins, 80–120%, with respect to the designed bias currents.

  1. Design and test of component circuits of an integrated quantum voltage noise source for Johnson noise thermometry

    Energy Technology Data Exchange (ETDEWEB)

    Yamada, Takahiro, E-mail: yamada-takahiro@aist.go.jp [Nanoelectronics Research Institute, National Institute of Advanced Industrial Science and Technology, Central 2, Umezono 1-1-1, Tsukuba, Ibaraki 305-8568 (Japan); Maezawa, Masaaki [Nanoelectronics Research Institute, National Institute of Advanced Industrial Science and Technology, Central 2, Umezono 1-1-1, Tsukuba, Ibaraki 305-8568 (Japan); Urano, Chiharu [National Metrology Institute of Japan, National Institute of Advanced Industrial Science and Technology, Central 3, Umezono 1-1-1, Tsukuba, Ibaraki 305-8563 (Japan)

    2015-11-15

    Highlights: • We demonstrated RSFQ digital components of a new quantum voltage noise source. • A pseudo-random number generator and variable pulse number multiplier are designed. • Fabrication process is based on four Nb wiring layers and Nb/AlOx/Nb junctions. • The circuits successfully operated with wide dc bias current margins, 80–120%. - Abstract: We present design and testing of a pseudo-random number generator (PRNG) and a variable pulse number multiplier (VPNM) which are digital circuit subsystems in an integrated quantum voltage noise source for Jonson noise thermometry. Well-defined, calculable pseudo-random patterns of single flux quantum pulses are synthesized with the PRNG and multiplied digitally with the VPNM. The circuit implementation on rapid single flux quantum technology required practical circuit scales and bias currents, 279 junctions and 33 mA for the PRNG, and 1677 junctions and 218 mA for the VPNM. We confirmed the circuit operation with sufficiently wide margins, 80–120%, with respect to the designed bias currents.

  2. Control of Grid Integrated Voltage Source Converters under Unbalanced Conditions: Development of an On-line Frequency-adaptive Virtual Flux-based Approach

    OpenAIRE

    Suul, Jon Are

    2012-01-01

    Three-Phase Voltage Source Converters (VSCs) are finding widespread applications in grid integrated power conversion systems. The control systems of such VSCs are in an increasing number of these applications required to operate during voltage disturbances and unbalanced conditions. Control systems designed for grid side voltagesensor- less operation are at the same time becoming attractive due to the continuous drive for cost reduction and increased reliability of VSCs, but are not commonly ...

  3. Evaluation of the drain—source voltage effect on AlGaAs/InGaAs PHEMTs thermal resistance by the structure function method

    International Nuclear Information System (INIS)

    Ma Lin; Feng Shiwei; Zhang Yamin; Deng Bing; Yue Yuan

    2014-01-01

    The effect of drain—source voltage on AlGaAs/InGaAs PHEMTs thermal resistance is studied by experimental measuring and simulation. The result shows that AlGaAs/InGaAs PHEMTs thermal resistance presents a downward trend under the same power dissipation when the drain—source voltage (V DS ) is decreased. Moreover, the relatively low V DS and large drain—source current (I DS ) result in a lower thermal resistance. The chip-level and package-level thermal resistance have been extracted by the structure function method. The simulation result indicated that the high electric field occurs at the gate contact where the temperature rise occurs. A relatively low V DS leads to a relatively low electric field, which leads to the decline of the thermal resistance. (semiconductor devices)

  4. Torque harmonics of an asynchronous motor supplied by a voltage- or current-sourced inverter quasi-square operation

    Energy Technology Data Exchange (ETDEWEB)

    Kyyrae, J. [Helsinki University of Technology, Institute of Intelligent Power Electronics, Espoo (Finland)

    1997-12-31

    Voltage- and current-sourced dc-ac converters operating in quasi-square area are compared. Their characteristics are calculated with switching vector, which is space-vector of switching functions. When the load is an asynchronous motor various analytical equations, including torque, are calculated efficiently. Motor current and torque approximations are compared with the simulated ones. (orig.) 6 refs.

  5. A sagging along the eastern Chianti Mts., Italy

    Science.gov (United States)

    Coltorti, M.; Ravani, S.; Cornamusini, G.; Ielpi, A.; Verrazzani, F.

    2009-11-01

    A deep-seated gravitational slope deformation (DGSD) affects the eastern side of the Chianti Mts. Ridge. It develops in an N-S to NW-SE direction and is > 10 km wide and 3-4 km long. This area corresponds to the eastern side of a main antiform, characterised by east-verging folds and thrusts involving bedrock of the Mesozoic-Paleogene Tuscan Units, particularly sandstones containing interlayered highly fractured and deformed Ligurian rocks (shales and limestones with olistostromes). The foot of the slope is characterised by tilted Plio-Pleistocene deposits unconformably sealing the bedrock structures as folds, thrusts and faults. The most significant morphological features are a main escarpment, trenches, several secondary and counter-slope escarpments that together indicate large-scale gravitational phenomena. The main escarpment is responsible for the headward retreat of the slope, and is deeply segmented by numerous arcuate niches that reveal differential movements of single blocks. The DGSD is also dissected by SW-NE trending streams that often deepen inside the N-S trenches. Minor landslides due to local instability are also present. At the foot of the slope, the older continental Pliocene deposits of the Upper Valdarno Basin crop out. Although tilted by tectonic movements, the deposits have not been severely affected by gravitational deformations. This indicates that the movement is a typical sagging, a large landslide at an embryonic stage, affecting the upper part of the slope but not reaching the valley bottom. The deformations are absorbed in the rock mass which is also partially drained by stream incision that prevents high pore pressure. The occurrence of down-slope and down-movement facing escarpments and up-slope and up-movement facing counter-slope escarpments indicate a sagging characterised by a listric spoon-shaped geometry. The DGSD has a style similar to crustal extensional tectonics such as Morton and Black's crustal attenuation model. Although

  6. Design-Oriented Analysis of Resonance Damping and Harmonic Compensation for LCL-Filtered Voltage Source Converters

    DEFF Research Database (Denmark)

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

    2014-01-01

    This paper addresses the interaction between harmonic resonant controllers and active damping of LCL resonance in voltage source converters. A virtual series R-C damper in parallel with the filter capacitor is proposed with the capacitor current feedback loop. The phase lag resulting from...... crossover frequency defined by the proportional gain of current controller. This is of particular interest for high-performance active harmonic filtering applications and low-pulse-ratio converters. Case studies in experiments validate the theoretical analysis....

  7. Vivitron 1995, transient voltage simulation, high voltage insulator tests, electric field calculation

    International Nuclear Information System (INIS)

    Frick, G.; Osswald, F.; Heusch, B.

    1996-01-01

    Preliminary investigations showed clearly that, because of the discrete electrode structure of the Vivitron, important overvoltage leading to insulator damage can appear in case of a spark. The first high voltage tests showed damage connected with such events. This fact leads to a severe voltage limitation. This work describes, at first, studies made to understand the effects of transients and the associated over-voltage appearing in the Vivitron. Then we present the high voltage tests made with full size Vivitron components using the CN 6 MV machine as a pilot machine. Extensive field calculations were made. These involve simulations of static stresses and transient overvoltages, on insulating boards and electrodes. This work gave us the solutions for arrangements and modifications in the machine. After application, the Vivitron runs now without any sparks and damage at 20 MV. In the same manner, we tested column insulators of a new design and so we will find out how to get to higher voltages. Electric field calculation around the tie bars connecting the discrete electrodes together showed field enhancements when the voltages applied on the discrete electrodes are not equally distributed. This fact is one of the sources of discharges and voltage limitations. A scenario of a spark event is described and indications are given how to proceed towards higher voltages, in the 30 MV range. (orig.)

  8. Voltage regulation of the Y-source boost DC-DC converter considering effects of leakage inductances based on cascaded sliding-mode control

    DEFF Research Database (Denmark)

    Ahmadzadeh, Soheil; Markadeh, Gholamreza Arab; Blaabjerg, Frede

    2017-01-01

    In this study, a sliding mode-based controller is designed for regulating the output voltage of a high step-up DC-DC converter with three coupled inductors called Y-source impedance network. As Y-source converter can provide a very high boost at a lower shoot-through duty cycle of the switch...

  9. Virtual RC Damping of LCL-Filtered Voltage Source Converters with Extended Selective Harmonic Compensation

    DEFF Research Database (Denmark)

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

    2015-01-01

    Active damping and harmonic compensation are two common challenges faced by LCL-filtered voltage source converters. To manage them holistically, this paper begins by proposing a virtual RC damper in parallel with the passive filter capacitor. The virtual damper is actively inserted by feeding back...... the passive capacitor current through a high-pass filter, which indirectly, furnishes two superior features. They are the mitigation of phase lag experienced by a conventional damper and the avoidance of instability caused by the negative resistance inserted unintentionally. Moreover, with the virtual RC...

  10. Grid-Current-Feedback Active Damping for LCL Resonance in Grid-Connected Voltage-Source Converters

    DEFF Research Database (Denmark)

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

    2016-01-01

    This paper investigates active damping of LCL-filter resonance in a grid-connected voltage-source converter with only grid-current feedback control. Basic analysis in the s-domain shows that the proposed damping technique with a negative high-pass filter along its damping path is equivalent...... of phase-lag, in turn, helps to shrink the region of nonminimum-phase behavior caused by negative virtual resistance inserted unintentionally by most digitally implemented active damping techniques. The presented high-pass-filtered active damping technique with a single grid-current feedback loop is thus...

  11. Improvement of voltage holding capability in the 500 keV negative ion source for JT-60SA.

    Science.gov (United States)

    Tanaka, Y; Hanada, M; Kojima, A; Akino, N; Shimizu, T; Ohshima, K; Inoue, T; Watanabe, K; Taniguchi, M; Kashiwagi, M; Umeda, N; Tobari, H; Grisham, L R

    2010-02-01

    Voltage holding capability of JT-60 negative ion source that has a large electrostatic negative ion accelerator with 45 cm x 1.1 m acceleration grids was experimentally examined and improved to realize 500 keV, 22 A, and 100 s D- ion beams for JT-60 Super Advanced. The gap lengths in the acceleration stages were extended to reduce electric fields in a gap between the large grids and at the corner of the support flanges from the original 4-5 to 3-4 kV/mm. As a result, the voltage holding capability without beam acceleration has been successfully improved from 400 to 500 kV. The pulse duration to hold 500 kV reached 40 s of the power supply limitation.

  12. Voltage Controlled Dynamic Demand Response

    DEFF Research Database (Denmark)

    Bhattarai, Bishnu Prasad; Bak-Jensen, Birgitte; Mahat, Pukar

    2013-01-01

    Future power system is expected to be characterized by increased penetration of intermittent sources. Random and rapid fluctuations in demands together with intermittency in generation impose new challenges for power balancing in the existing system. Conventional techniques of balancing by large...... central or dispersed generations might not be sufficient for future scenario. One of the effective methods to cope with this scenario is to enable demand response. This paper proposes a dynamic voltage regulation based demand response technique to be applied in low voltage (LV) distribution feeders....... An adaptive dynamic model has been developed to determine composite voltage dependency of an aggregated load on feeder level. Following the demand dispatch or control signal, optimum voltage setting at the LV substation is determined based on the voltage dependency of the load. Furthermore, a new technique...

  13. Analysis of changes in sagging type ST-T segment induced by exercise. Assessment of regional myocardial blood flow using quantitative 13NH3 positron emission tomography

    International Nuclear Information System (INIS)

    Watanabe, Takuya; Akutsu, Yasushi; Okazaki, Osamu

    1995-01-01

    Regional myocardial blood flow (RMBF) associated with exercise-induced ST depression was assessed using 13 NH 3 positron emission tomography (PET) to determine the significance of horizontal and sagging type ST segments. The subjects were 25 patients with angina pectoris, 25 patients with myocardial infarction, and 5 healthy male volunteers. Eleven regions of interests (ROI) were prepared to calculate RMBF. ST segments were unchanged in 27 patients (Group A) and were depressed in 23 patients (Group B). A 10% increase in RMBF was significantly observed in Group A (74.1%) than Group B (34.8%). In Group B, ST depression was divided into horizontal type (8 patients) and sagging type (15 patients). According to the type of ST depression, RMBF was increased by 10% or more in 50% (4/8) for horizontal type and in 26.7% (4/15) for sagging type. These findings suggested that unfavorable increase in RMBF in stenosiss-related coronary vessels may contribute to the development of ST depression induced by exercise. A constant increase in RMBF in all ROIs, including those with unfavorable RMBF increase, may be involved in the occurrence of horizontal type ST depression; sagging type ST depression may, however, occur by an increased difference in blood flow between unfavorable and favorable RMBF. (N.K.)

  14. High voltage MOSFET switching circuit

    Science.gov (United States)

    McEwan, Thomas E.

    1994-01-01

    The problem of source lead inductance in a MOSFET switching circuit is compensated for by adding an inductor to the gate circuit. The gate circuit inductor produces an inductive spike which counters the source lead inductive drop to produce a rectangular drive voltage waveform at the internal gate-source terminals of the MOSFET.

  15. Drowning unconformity of lacustrine rift basins: A case study from the Dongying Sag in Bohai Bay Basin, China

    Science.gov (United States)

    Chen, R.; Fan, J.

    2015-12-01

    The concept of drowning unconformity of lacustrine rift basins was proposed in this paper. This paper utilized 3D seismic data, well-log and the principles methods associated with structural geology, sedimentology and geochemistry, to analyze the drowning unconformity and discuss the origins of drowning unconformity in Dongying Sag in Bohai Bay Basin.Researching on it is not only important for a better understanding of tectonic evolution, palaeogeography and sedimentation of hydrocarbon source rocks, but also a vital guiding significance for the exploration of beach-bar sandstone reservoirs and shale oil.1. The concept of drowning unconformity of lacustrine rift basins is defined. With the consequences of rapid tectonic subsidence in basin, the sharp rise of lake-level and the increased rate of accommodation(A) in basin exceeded the rate of sediment supply(S),namely A>>S, the basin suddenly transformed into deep-water settings from shallow-water settings with sudden change of sediment transport and sediment dispersal patterns. 2.The sequence surface between Sha4 and Sha3 Member of Shahejie Formation is the drowning unconformity(43.5Ma). There are the sedimentary association of the reefs in shallow lacustrine, beach-bar sandstones and glutenite fan bodies under the surface. By contrast, there are the sedimentary association of deep-lake oil shales and shales over the surface. The drowning unconformity in Dongying Sag is a tectonic revolution surface which is changed from extensional tectonics to transtensional tectonics and it is also the surface of discontinuity from shallow lacustrine to deep lacustrine. The responses to sudden changes appeared in the parameters of geophysics, geochemistry and paleontology. 3. With the penetration of India into Asia plate in NNE trending,the subduction zones of Pacific Plate retreated. It caused the rapid downwelling of asthenospheric mantle, followed by the extensive drowning unconformity.

  16. Induced Voltage in an Open Wire

    Science.gov (United States)

    Morawetz, K.; Gilbert, M.; Trupp, A.

    2017-07-01

    A puzzle arising from Faraday's law has been considered and solved concerning the question which voltage will be induced in an open wire with a time-varying homogeneous magnetic field. In contrast to closed wires where the voltage is determined by the time variance of the magnetic field and the enclosed area, in an open wire we have to integrate the electric field along the wire. It is found that the longitudinal electric field with respect to the wave vector contributes with 1/3 and the transverse field with 2/3 to the induced voltage. In order to find the electric fields the sources of the magnetic fields are necessary to know. The representation of a spatially homogeneous and time-varying magnetic field implies unavoidably a certain symmetry point or symmetry line which depend on the geometry of the source. As a consequence the induced voltage of an open wire is found to be the area covered with respect to this symmetry line or point perpendicular to the magnetic field. This in turn allows to find the symmetry points of a magnetic field source by measuring the voltage of an open wire placed with different angles in the magnetic field. We present exactly solvable models of the Maxwell equations for a symmetry point and for a symmetry line, respectively. The results are applicable to open circuit problems like corrosion and for astrophysical applications.

  17. METODOLOGÍA GENERAL PARA CORRELACIONAR SAGS CON EVENTOS AMBIENTALES U OPERATIVOS DEL SISTEMA DE DISTRIBUCIÓN

    Directory of Open Access Journals (Sweden)

    Alejandro Castillo Guasca

    2013-07-01

    Full Text Available Es de gran importancia conocer cuáles son las causas  para que se presenten sags en las barrajes de distribución, debido a que la afectación sobre los clientes industriales es de carácter relevante. Por esta razón se planteó  una metodología para buscar la correlación existente entre sags y los eventos ambientales u operativos del sistema de distribución. A manera de ejemplo, se aplicó en tres subestaciones, las cuales se encuentran ubicadas en diferentes sectores de la ciudad. Para el desarrollo de esta metodología, se realizó la correlación de los datos mediante la implementación de tablas dinámicas y programación en Access, donde se evidenció qué tipo de eventos son los que tienen un mayor impacto sobre los clientes. De acuerdo a los resultados obtenidos se sugiere algunas recomendaciones para mitigar este tipo de eventos en el sistema de distribución.

  18. Neuro-fuzzy-wavelet network for detection and classification of the voltage disturbances in electrical power system; Rede neuro-fuzzy-wavelet para deteccao e classificacao de anomalias de tensao em sistemas eletricos de potencia

    Energy Technology Data Exchange (ETDEWEB)

    Malange, Fernando C.V. [Universidade do Estado de Mato Grosso (UEMT), Caceres, MT (Brazil). Dept. de Computacao], E-mail: fmalange@gmail.com; Minussi, Carlos R. [Universidade Estadual Paulista (UNESP), Ilha Solteira, SP (Brazil). Dept. de Engenharia Eletrica], E-mail: minussi@dee.feis.unesp.br

    2009-07-01

    A methodology for identifying and classifying voltage disturbances (harmonics, voltage sag, etc.) using fuzzy ARTMAP neural networks is presented. It is an ART (adaptive resonance theory) architecture family neural network that presents the stability and plasticity properties, which are fundamental requests for developing a reliable electrical systems with reduced processing time. Stability means a guarantee of good solutions; plasticity allows realize the training without restart the system every time there are new patterns to be stored in a weight matrix of the neural network. The training is realized from the wave forms provided by the acquisition data system, using the wavelets theory to generate the coefficients that constitute the input patterns of the neural network. Results from simulations show that the accuracy index is nearly 100%. (author)

  19. The pulse-driven AC Josephson voltage normal

    International Nuclear Information System (INIS)

    Kieler, Oliver

    2016-01-01

    In this contribution quantum precise alternating-voltage sources are presented, which make the generation of arbitrary wave forms with highest spectral purity with a high bandwidth from DC up to the MHz range possible. Heartpiece of these Josephson voltage normals is a serial circuit of many thousand Josephson contacts, which make by irradiation with high-frequency radiation (microwaves) the generation of highly precise voltage values possible. Thereby in the current-voltage characteristics stages of constant voltage, so called Shapiro stages, occur. Illustratively these stages can be described by the transfer of a certain number of flux quanta through the Josephson contacts.

  20. Mitigating voltage lead errors of an AC Josephson voltage standard by impedance matching

    Science.gov (United States)

    Zhao, Dongsheng; van den Brom, Helko E.; Houtzager, Ernest

    2017-09-01

    A pulse-driven AC Josephson voltage standard (ACJVS) generates calculable AC voltage signals at low temperatures, whereas measurements are performed with a device under test (DUT) at room temperature. The voltage leads cause the output voltage to show deviations that scale with the frequency squared. Error correction mechanisms investigated so far allow the ACJVS to be operational for frequencies up to 100 kHz. In this paper, calculations are presented to deal with these errors in terms of reflected waves. Impedance matching at the source side of the system, which is loaded with a high-impedance DUT, is proposed as an accurate method to mitigate these errors for frequencies up to 1 MHz. Simulations show that the influence of non-ideal component characteristics, such as the tolerance of the matching resistor, the capacitance of the load input impedance, losses in the voltage leads, non-homogeneity in the voltage leads, a non-ideal on-chip connection and inductors between the Josephson junction array and the voltage leads, can be corrected for using the proposed procedures. The results show that an expanded uncertainty of 12 parts in 106 (k  =  2) at 1 MHz and 0.5 part in 106 (k  =  2) at 100 kHz is within reach.

  1. High-performance feedback-type active damping of LCL-filtered voltage source converters

    DEFF Research Database (Denmark)

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

    2015-01-01

    a generalized impedance-based model of grid current control with feedback-type active damping. Then, a controller design method based on the z-domain root contours and frequency-domain passivity theorem is proposed. It not only allows a co-design of the grid current controller and damping controller......Active damping of LCL-filter resonance based on single-state feedback control is widely used with voltage source converters. Its robustness against grid impedance variation has always been a major concern with its controller design. To deal with this issue, this paper begins by developing......, but ensures also a robust stabilization against the grid parameters variations. For illustration, the approach is applied to design three single-state feedback-damping schemes, and their damping robustness are compared under both inductive and resonant grid impedances. Experimental results validate...

  2. Synchronised Voltage Space Vector Modulation for Three-level Inverters with Common-mode Voltage Elimination

    DEFF Research Database (Denmark)

    Oleschuk, Valentin; Blaabjerg, Frede

    2002-01-01

    A novel method of direct synchronous pulse-width modulation (PWM) is disseminated to three-level voltage source inverters with control algorithms with elimination of the common-mode voltages in three-phase drive systems with PWM. It provides smooth pulses-ratio changing and a quarter-wave symmetry...... of the voltage waveforms during the whole control range including overmodulation. Continuous, discontinuous and "direct-direct" schemes of synchronous PWM with both algebraic and trigonometric control functions have been analysed and compared. Simulations give the behaviour of the proposed methods and show some...... advantages of synchronous PWM in comparison with asynchronous at low ratios between the switching frequency and fundamental frequency....

  3. SU-E-T-459: Impact of Source Position and Traveling Time On HDR Skin Surface Applicator Dosimetry

    International Nuclear Information System (INIS)

    Jeong, J; Barker, C; Zaider, M; Cohen, G

    2015-01-01

    Purpose: Observed dosimetric discrepancy between measured and treatment planning system (TPS) predicted values, during applicator commissioning, were traced to source position uncertainty in the applicator. We quantify the dosimetric impact of this geometric uncertainty, and of the source traveling time inside the applicator, and propose corrections for clinical use. Methods: We measured the dose profiles from the Varian Leipzig-style (horizontal) HDR skin applicator, using EBT3 film, photon diode, and optically stimulated luminescence dosimeter (OSLD) and three different GammaMed HDR afterloders. The dose profiles and depth dose of each aperture were measured at several depths (up to about 10 mm, depending on the dosimeter). The measured dose profiles were compared with Acuros calculated profiles in BrachyVision TPS. For the impact of the source position, EBT3 film measurements were performed with applicator, facing-down and facing-up orientations. The dose with and without source traveling was measured with diode detector using HDR timer and electrometer timer, respectively. Results: Depth doses measured using the three dosimeters were in good agreement, but were consistently higher than the Acuros dose calculations. Measurements with the applicator facing-up were significantly lower than those in the facing-down position with maximum difference of about 18% at the surface, due to source sag inside the applicator. Based on the inverse-square law, the effective source sag was evaluated to be about 0.5 mm from the planned position. The additional dose from the source traveling was about 2.8% for 30 seconds with 10 Ci source, decreasing with increased dwelling time and decreased source activity. Conclusion: Due to the short source-to-surface distance of the applicator, the small source sag inside the applicator has significant dosimetric impact, which should be considered before the clinical use of the applicator. Investigation of the effect for other applicators

  4. An analytical threshold voltage model for a short-channel dual-metal-gate (DMG) recessed-source/drain (Re-S/D) SOI MOSFET

    Science.gov (United States)

    Saramekala, G. K.; Santra, Abirmoya; Dubey, Sarvesh; Jit, Satyabrata; Tiwari, Pramod Kumar

    2013-08-01

    In this paper, an analytical short-channel threshold voltage model is presented for a dual-metal-gate (DMG) fully depleted recessed source/drain (Re-S/D) SOI MOSFET. For the first time, the advantages of recessed source/drain (Re-S/D) and of dual-metal-gate structure are incorporated simultaneously in a fully depleted SOI MOSFET. The analytical surface potential model at Si-channel/SiO2 interface and Si-channel/buried-oxide (BOX) interface have been developed by solving the 2-D Poisson’s equation in the channel region with appropriate boundary conditions assuming parabolic potential profile in the transverse direction of the channel. Thereupon, a threshold voltage model is derived from the minimum surface potential in the channel. The developed model is analyzed extensively for a variety of device parameters like the oxide and silicon channel thicknesses, thickness of source/drain extension in the BOX, control and screen gate length ratio. The validity of the present 2D analytical model is verified with ATLAS™, a 2D device simulator from SILVACO Inc.

  5. The Study of a Nonlinear Duffing – Type Oscillator Driven by Two Voltage Sources

    Directory of Open Access Journals (Sweden)

    J. O. Maaita

    2013-10-01

    Full Text Available In the present work, a detailed study of a nonlinear electrical oscillator with damping and external excitation is presented. The system under study consists of a Duffing-type circuit driven by two sinusoidal voltage sources having different frequencies. The dynamical behavior of the proposed system is investigated numerically, by solving the system of state equations and simulating its behavior as a circuit using MultiSim. The tools of the theoretical approach are the bifurcation diagrams, the Poincaré sections, the phase portraits, and the maximum Lyapunov exponent. The numerical investigation showed that the system has rich complex dynamics including phenomena such as quasiperiodicity, 3-tori, and chaos.

  6. On-line Dynamic Security Assessment in Power Systems

    DEFF Research Database (Denmark)

    Weckesser, Johannes Tilman Gabriel

    and solar radiation. Moreover, ongoing research suggests that demand response will be introduced to maintain power balance between generation and consumption at all times. Due to these changes the operating point of the power system will be less predictable and today’s stability and security assessment...... for early prediction of critical voltage sags is described. The method’s performance is compared to other prediction approaches. The results show that the proposed method succeeds in early, accurately and consistently predicting critically low voltage sags. An efficient on-line DSA not only identifies...

  7. Dual-Source Dual-Energy CT Angiography of the Supra-Aortic Arteries with Tin Filter: Impact of Tube Voltage Selection.

    Science.gov (United States)

    Korn, Andreas; Bender, Benjamin; Schabel, Christoph; Bongers, Malte; Ernemann, Ulrike; Claussen, Claus; Thomas, Christoph

    2015-06-01

    Automatic bone and plaque subtraction (BPS) in computed tomographic angiographic (CTA) examinations using dual-energy CT (DECT) remains challenging because of beam-hardening artifacts in the shoulder region and close proximity of the internal carotid artery to the base of the skull. The selection of the tube voltage combination in dual-source CT influences the spectral separation and the susceptibility for artifacts. The purpose of this study was to assess which tube voltage combination leads to an optimal image quality of head and neck DECT angiograms after bone subtraction. Fifty-one patients received tin-filter-enhanced DECT angiograms of the supra-aortic arteries using two voltage protocols: 24 patients were studied using 80/Sn140 kV and 27 using a 100/Sn140 kV protocol, both protocols with an additional tin filter. A commercially available DE-CTA BPS algorithm was used. Artificial vessel erosions in BPS maximum intensity projections (four-level Likert scale with CTA source data as reference) and vessel signal-to-noise ratio (SNR) were assessed in the level of the shoulders and the base of the skull in each patient and compared. At the level of the shoulder, 100/Sn140 kV achieved higher SNR (23.4 ± 6.4 at 80/Sn140 kV vs. 35.1 ± 11.8 at 100/Sn140 kV; P supra-aortic arteries than the 80/Sn140 kV protocol. Copyright © 2015 AUR. Published by Elsevier Inc. All rights reserved.

  8. Estimation of the Plant Time Constant of Current-Controlled Voltage Source Converters

    DEFF Research Database (Denmark)

    Vidal, Ana; Yepes, Alejandro G.; Malvar, Jano

    2014-01-01

    Precise knowledge of the plant time constant is essential to perform a thorough analysis of the current control loop in voltage source converters (VSCs). As the loop behavior can be significantly influenced by the VSC working conditions, the effects associated to converter losses should be included...... in the model, through an equivalent series resistance. In a recent work, an algorithm to identify this parameter was developed, considering the inductance value as known and practically constant. Nevertheless, the plant inductance can also present important uncertainties with respect to the inductance...... of the VSC interface filter measured at rated conditions. This paper extends that method so that both parameters of the plant time constant (resistance and inductance) are estimated. Such enhancement is achieved through the evaluation of the closed-loop transient responses of both axes of the synchronous...

  9. Analysis of a DVR with Molten Carbonate Fuel Cell and Fuzzy Logic Control

    Directory of Open Access Journals (Sweden)

    J. Chakravorty

    2018-04-01

    Full Text Available As power demand constantly (and rapidly increases and with the introduction of many sophisticated electronic devices, power quality issues are becoming a major problem for the power sector. In this context, issues of power quality, voltage swells and sags have become rather common. Custom power devices are generally used to solve this problem. A dynamic voltage restorer (DVR is the most efficient and effective modern custom power device used in power distribution networks. In this paper a new DVR model is presented. The proposed DVR has a molten carbonate fuel cell (MCFC as its DC source of supply with an ultra-capacitor along with a fuzzy controller as its controlling unit. The complete model is implemented in MATLAB/SIMULINK and the output of the proposed model is compared with conventional DVR model with a simple DC voltage source and a capacitor with the same fuzzy controller

  10. Analysis of Voltage Forming Methods for Multiphase Inverters

    Directory of Open Access Journals (Sweden)

    Tadas Lipinskis

    2013-05-01

    Full Text Available The article discusses advantages of the multiphase AC induction motor over three or less phase motors. It presents possible stator winding configurations for a multiphase induction motor. Various fault control strategies were reviewed for phases feeding the motor. The authors propose a method for quality evaluation of voltage forming algorithm in the inverter. Simulation of a six-phase voltage source inverter, voltage in which is formed using a simple SPWM control algorithm, was performed in Matlab Simulink. Simulation results were evaluated using the proposed method. Inverter’s power stage was powered by 400 V DC source. The spectrum of output currents was analysed and the magnitude of the main frequency component was at least 12 times greater than the next biggest-magnitude component. The value of rectified inverter voltage was 373 V.Article in Lithuanian

  11. DC-Voltage Fluctuation Elimination Through a DC-Capacitor Current Control for DFIG Converters Under Unbalanced Grid Voltage Conditions

    DEFF Research Database (Denmark)

    Liu, Changjin; Xu, Dehong; Zhu, Nan

    2013-01-01

    Unbalanced grid voltage causes a large second-order harmonic current in the dc-link capacitors as well as dc-voltage fluctuation, which potentially will degrade the lifespan and reliability of the capacitors in voltage source converters. This paper proposes a novel dc-capacitor current control...... method for a grid-side converter (GSC) to eliminate the negative impact of unbalanced grid voltage on the dc-capacitors. In this method, a dc-capacitor current control loop, where a negative-sequence resonant controller is used to increase the loop gain, is added to the conventional GSC current control...... loop. The rejection capability to the unbalanced grid voltage and the stability of the proposed control system are discussed. The second-order harmonic current in the dc capacitor as well as dc-voltage fluctuation is very well eliminated. Hence, the dc capacitors will be more reliable under unbalanced...

  12. Constant potential high-voltage generator

    International Nuclear Information System (INIS)

    Resnick, T.A.; Dupuis, W.A.; Palermo, T.

    1980-01-01

    An X-ray tube voltage generator with automatic stabilization circuitry is disclosed. The generator includes a source of pulsating direct current voltage such as from a rectified 3 phase transformer. This pulsating voltage is supplied to the cathode and anode of an X-ray tube and forms an accelerating potential for electrons within that tube. The accelerating potential is stabilized with a feedback signal which is provided by a feedback network. The network includes an error signal generator which compares an instantaneous accelerating potential with a preferred reference accelerating potential and generates an error function. This error function is transmitted to a control tube grid which in turn causes the voltage difference between X-ray tube cathode and anode to stabilize and thereby reduce the error function. In this way stabilized accelerating potentials are realized and uniform X-ray energy distributions produced. (Auth.)

  13. Distributed Control to Ensure Proportional Load Sharing and Improve Voltage Regulation in Low-Voltage DC Microgrids

    DEFF Research Database (Denmark)

    Anand, Sandeep; G. Fernandes, Baylon; Guerrero, Josep M.

    2013-01-01

    DC microgrids are gaining popularity due to high efficiency, high reliability, and easy interconnection of renewable sources as compared to the ac system. Control objectives of dc microgrid are: 1) to ensure equal load sharing (in per unit) among sources; and 2) to maintain low-voltage regulation...

  14. Power angle control of grid-connected voltage source converter in a wind energy application

    Energy Technology Data Exchange (ETDEWEB)

    Svensson, Jan [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Electric Power Engineering

    1996-12-31

    In this thesis, the connection of a voltage source converter to the grid in a wind energy application is examined. The possibility of using a cheap control system without grid current measurements, is investigated. The control method is based on controlling the voltage angle of the inverter, which governs the active power flow. The highest frequency of the power variation, coming from wind turbine, is approx. 5 Hz. Since the proposed control method easily can handle such power variations it is very well suited for wind turbine applications. The characteristics of the system depend on the DC-link capacitor, the grid filter inductance and resistance. Large values of the resistance damp the system well but increase the energy losses. A high inductance leads to a reduced harmonic level on the grid but makes the system slower. By using feed-forward of the generator/rectifier current signal, the performance is increased compared to an ordinary PI-control. Combining the Linear Quadratic (LQ) control method with Kalman filtered input signals, a robust control method with a good performance is obtained. The LQ controller controls both the phase displacement angle and the modulation index, resulting in higher bandwidth, and the typical power angle resonance at the grid frequency disappears. 22 refs, 109 figs, 14 tabs

  15. Solar cell power source system

    Energy Technology Data Exchange (ETDEWEB)

    Shimizu, Yoichi; Toma, Kunio; Fukuwa, Shinji

    1988-05-14

    This invention aims to supply a power source system with stable power output by reducing the power loss due to switching in the voltage stabilization even when the power source is a solar cell with frequent voltage variation. For this purpose, in a solar cell power source system consisting of a solar cell, a storage battery, a switching regulator placed between the storage cell and the load, and a load, arrangement was made that, by judging the input voltage from the storage battery, switch-acting the transistor of the switching regulator, if the input voltage is higher than the specified voltage; is the input voltage is lower than the specified voltage, the transistor is put in a full-on state. By this, the supply voltage can be stabilized even when the voltage fluctuates, and system gets more efficient as the switching loss decreases in the voltage stabilizing means. (1 fig)

  16. A low-ripple chargepump circuit for high voltage applications

    NARCIS (Netherlands)

    Berkhout, M.; Berkhout, M.; van Steenwijk, G.; van Steenwijk, Gijs; van Tuijl, Adrianus Johannes Maria

    1995-01-01

    The subject of this paper is a fully integrated chargepump circuit with a very low output voltage ripple. At a supply voltage of 30V the chargepump can source 1mA at an output voltage of 40V. Two simple modifications to the classical chargepump circuit give a substantial reduction of the output

  17. Deposition and characterization of zirconium nitride (ZrN) thin films by reactive magnetron sputtering with linear gas ion source and bias voltage

    Energy Technology Data Exchange (ETDEWEB)

    Kavitha, A.; Kannan, R. [Department of Physics, University College of Engineering, Anna University, Dindugal-624622 (India); Subramanian, N. Sankara [Department of Physics, Thiagarajar College of Engineering, Madurai -625015, Tamilnadu (India); Loganathan, S. [Ion Plating, Titan Industries Ltd., Hosur - 635126, Tamilnadu (India)

    2014-04-24

    Zirconium nitride thin films have been prepared on stainless steel substrate (304L grade) by reactive cylindrical magnetron sputtering method with Gas Ion Source (GIS) and bias voltage using optimized coating parameters. The structure and surface morphologies of the ZrN films were characterized using X-ray diffraction, atomic microscopy and scanning electron microscopy. The adhesion property of ZrN thin film has been increased due to the GIS. The coating exhibits better adhesion strength up to 10 N whereas the ZrN thin film with bias voltage exhibits adhesion up to 500 mN.

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

    Directory of Open Access Journals (Sweden)

    Yong Chen

    2016-01-01

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

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

    Science.gov (United States)

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

    2017-08-29

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

  20. Influence of modulation method on using LC-traps with single-phase voltage source converters

    DEFF Research Database (Denmark)

    Wang, Xiongfei; Min, Huang; Bai, Haofeng

    2015-01-01

    The switching-frequency LC-trap filter has recently been employed with high-order passive filters for Voltage Source Inverters (VSIs). This paper investigates the influence of modulation method on using the LC-traps with single-phase VSIs. Two-level (bipolar) and three-level (unipolar) modulations...... that include phase distortion and alternative phase opposition distortion methods are analyzed. Harmonic filtering performances of four LC-trap-based filters with different locations of LC-traps are compared. It is shown that the use of parallel-LC-traps in series with filter inductors, either grid...... or converter side, has a worse harmonic filtering performance than using series-LC-trap in the shunt branch. Simulations and experimental results are presented for verifications....

  1. Episodic normal faulting and magmatism during the syn-spreading stage of the Baiyun sag in Pearl River Mouth Basin: response to the multi-phase seafloor spreading of the South China Sea

    Science.gov (United States)

    Deng, Peng; Mei, Lianfu; Liu, Jun; Zheng, Jinyun; Liu, Minghui; Cheng, Zijie; Guo, Fengtai

    2018-03-01

    Considerable post-breakup extensional deformation is recorded in the continental margins of the South China Sea (SCS). To recognize the nature and origin of the significant deformation during the syn-spreading stage (32-15.5 Ma) in the SCS, we comprehensively analyzed the geometry and kinematics of the faults and contemporaneous magmas in the Baiyun sag, northern margin of the SCS, using high-resolution regional three-dimensional seismic data. The kinematic analyses indicate that the faults in the Baiyun sag are recently formed following the onset of seafloor spreading in the SCS. The faults exhibit multiple episodes of growth history, with three active episodes, 32-29, 23.8-21 and 18.5-16.5 Ma, separated by periods of inactivity. Four volcanic groups comprising 98 volcanic mounds have been identified and described, located separately in the northwestern, the central, the southeastern and the northern slope areas. The occurrence of multiple palaeo-seafloors, complemented by the biostratigraphic and K-Ar dating data, reveals multiple extrusive events of the syn-spreading magmas in the Baiyun sag, with three active periods of 23.8-21, 18.5-17.5 and 17.5-16.5 Ma. This study confirms that the normal faulting has a shared genetic origin with the contemporaneous magmatism during the syn-spreading stage in the deep-offshore Baiyun sag, northern margin of the SCS. The episodic fault growth and magmatic extrusive events reveal that the Baiyun sag has undergone at least three episodic tectonic events during the syn-spreading stage, which evolved in response to the multi-stage seafloor spreading of the SCS.

  2. Effects of Electrode Material on the Voltage of a Tree-Based Energy Generator.

    Science.gov (United States)

    Hao, Zhibin; Wang, Guozhu; Li, Wenbin; Zhang, Junguo; Kan, Jiangming

    2015-01-01

    The voltage between a standing tree and its surrounding soil is regarded as an innovative renewable energy source. This source is expected to provide a new power generation system for the low-power electrical equipment used in forestry. However, the voltage is weak, which has caused great difficulty in application. Consequently, the development of a method to increase the voltage is a key issue that must be addressed in this area of applied research. As the front-end component for energy harvesting, a metal electrode has a material effect on the level and stability of the voltage obtained. This study aimed to preliminarily ascertain the rules and mechanisms that underlie the effects of electrode material on voltage. Electrodes of different materials were used to measure the tree-source voltage, and the data were employed in a comparative analysis. The results indicate that the conductivity of the metal electrode significantly affects the contact resistance of the electrode-soil and electrode-trunk contact surfaces, thereby influencing the voltage level. The metal reactivity of the electrode has no significant effect on the voltage. However, passivation of the electrode materials markedly reduces the voltage. Suitable electrode materials are demonstrated and recommended.

  3. High-performance control of a three-phase voltage-source converter including feedforward compensation of the estimated load current

    International Nuclear Information System (INIS)

    Leon, Andres E.; Solsona, Jorge A.; Busada, Claudio; Chiacchiarini, Hector; Valla, Maria Ines

    2009-01-01

    In this paper a new control strategy for voltage-source converters (VSC) is introduced. The proposed strategy consists of a nonlinear feedback controller based on feedback linearization plus a feedforward compensation of the estimated load current. In our proposal an energy function and the direct-axis current are considered as outputs, in order to avoid the internal dynamics. In this way, a full linearization is obtained via nonlinear transformation and feedback. An estimate of the load current is feedforwarded to improve the performance of the whole system and to diminish the capacitor size. This estimation allows to obtain a more rugged and cheaper implementation. The estimate is calculated by using a nonlinear reduced-order observer. The proposal is validated through different tests. These tests include performance in presence of switching frequency, measurement filters delays, parameters uncertainties and disturbances in the input voltage.

  4. Model development for prediction and mitigation of dissolved oxygen sags in the Athabasca River, Canada

    Energy Technology Data Exchange (ETDEWEB)

    Martin, Nancy, E-mail: nancy@ualberta.ca [Department of Civil and Environmental Engineering, University of Alberta, Edmonton, AB, Canada T6G 2W2 (Canada); McEachern, Preston [Tervita Corporation, AB (Canada); Yu, Tong; Zhu, David Z. [Department of Civil and Environmental Engineering, University of Alberta, Edmonton, AB, Canada T6G 2W2 (Canada)

    2013-01-15

    Northern rivers exposed to high biochemical oxygen demand (BOD) loads are prone to dissolved oxygen (DO) sags in winter due to re-aeration occurring within limited open water leads. Additionally, photosynthesis is reduced by decreased daylight hours, inability of solar radiation to pass through ice, and slower algal growth in winter. The low volumetric flow decreases point-source dilution while their travel time increases. The Athabasca River in Alberta, Canada, has experienced these sags which may affect the aquatic ecosystem. A water quality model for an 800 km reach of this river was customized, calibrated, and validated specifically for DO and the factors that determine its concentration. After validation, the model was used to assess the assimilative capacity of the river and mitigation measures that could be deployed. The model reproduced the surface elevation and water temperature for the seven years simulated with mean absolute errors of < 15 cm and < 0.9 °C respectively. The ice cover was adequately predicted for all seven winters, and the simulation of nutrients and phytoplankton primary productivity were satisfactory. The DO concentration was very sensitive to the sediment oxygen demand (SOD), which represented about 50% of the DO sink in winter. The DO calibration was improved by implementing an annual SOD based on the BOD load. The model was used to estimate the capacity of the river to assimilate BOD loads in order to maintain a DO concentration of 7 mg/L, which represents the chronic provincial guideline plus a buffer of 0.5 mg/L. The results revealed the maximum assimilative BOD load of 8.9 ton/day at average flow conditions, which is lower than the maximum permitted load. In addition, the model predicted a minimum assimilative flow of about 52 m{sup 3}/s at average BOD load. Climate change scenarios could increase the frequency of this low flow. A three-level warning-system is proposed to manage the BOD load proactively at different river

  5. Serially Connected Micro Amorphous Silicon Solar Cells for Compact High-Voltage Sources

    Directory of Open Access Journals (Sweden)

    Jiyoon Nam

    2016-01-01

    Full Text Available We demonstrate a compact amorphous silicon (a-Si solar module to be used as high-voltage power supply. In comparison with the organic solar module, the main advantages of the a-Si solar module are its compatibility with photolithography techniques and relatively high power conversion efficiency. The open circuit voltage of a-Si solar cells can be easily controlled by serially interconnecting a-Si solar cells. Moreover, the a-Si solar module can be easily patterned by photolithography in any desired shapes with high areal densities. Using the photolithographic technique, we fabricate a compact a-Si solar module with noticeable photovoltaic characteristics as compared with the reported values for high-voltage power supplies.

  6. An analog RF gap voltage regulation system for the Advanced Photon Source storage ring

    International Nuclear Information System (INIS)

    Horan, D.

    1999-01-01

    An analog rf gap voltage regulation system has been designed and built at Argonne National Laboratory to maintain constant total storage ring rf gap voltage, independent of beam loading and cavity tuning effects. The design uses feedback control of the klystron mod-anode voltage to vary the amount of rf power fed to the storage ring cavities. The system consists of two independent feedback loops, each regulating the combined rf gap voltages of eight storage ring cavities by varying the output power of either one or two rf stations, depending on the mode of operation. It provides full operator control and permissive logic to permit feedback control of the rf system output power only if proper conditions are met. The feedback system uses envelope-detected cavity field probe outputs as the feedback signal. Two different methods of combining the individual field probe signals were used to generate a relative DC level representing one-half of the total storage ring rf voltage, an envelope-detected vector sum of the field probe rf signals, and the DC sum of individual field probe envelope detector outputs. The merits of both methods are discussed. The klystron high-voltage power supply (HVPS) units are fitted with an analog interface for external control of the mod-anode voltage level, using a four-quadrant analog multiplier to modulate the HVPS mod-anode voltage regulator set-point in response to feedback system commands

  7. Avaliação do antígeno SAG2a recombinante de Toxoplasma gondii como um potencial marcador diagnóstico para Toxoplasmose humana aguda

    OpenAIRE

    Béla, Samantha Ribeiro

    2007-01-01

    Proteínas recombinantes têm sido utilizadas para o diagnóstico sorológico da infecção por Toxoplasma gondii para diferenciar entre as fases aguda e crônica da toxoplasmose. Neste estudo, foi avaliada a reatividade de anticorpos IgG e IgG1 através de imunoensaios em soros de pacientes com toxoplasmose aguda e crônica dirigidos contra dois antígenos recombinantes clonados e expressos em E. coli, SAG2A (molécula recombinante total) e SAG2A(DELTA) (molécula recombinante deletada do...

  8. A dual-energy medical instrument for measurement of x-ray source voltage and dose rate

    Science.gov (United States)

    Ryzhikov, V. D.; Naydenov, S. V.; Volkov, V. G.; Opolonin, O. D.; Makhota, S.; Pochet, T.; Smith, C. F.

    2016-03-01

    An original dual-energy detector and medical instrument have been developed to measure the output voltages and dose rates of X-ray sources. Theoretical and experimental studies were carried out to characterize the parameters of a new scintillator-photodiode sandwich-detector based on specially-prepared zinc selenide crystals in which the low-energy detector (LED) works both as the detector of the low-energy radiation and as an absorption filter allowing the highenergy fraction of the radiation to pass through to the high-energy detector (HED). The use of the LED as a low-energy filter in combination with a separate HED opens broad possibilities for such sandwich structures. In particular, it becomes possible to analyze and process the sum, difference and ratio of signals coming from these detectors, ensuring a broad (up to 106) measurement range of X-ray intensity from the source and a leveling of the energy dependence. We have chosen an optimum design of the detector and the geometry of the component LED and HED parts that allow energy-dependence leveling to within specified limits. The deviation in energy dependence of the detector does not exceed about 5% in the energy range from 30 to 120 keV. The developed detector and instrument allow contactless measurement of the anode voltage of an X-ray emitter from 40 to 140 kV with an error no greater than 3%. The dose rate measurement range is from 1 to 200 R/min. An original medical instrument has passed clinical testing and was recommended for use in medical institutions for X-ray diagnostics.

  9. On Stability of Voltage Source Inverters in Weak Grids

    DEFF Research Database (Denmark)

    Adib, Aswad; Mirafza, Behrooz; Wang, Xiongfei

    2018-01-01

    As the number of inverters increases in the power grid, the stability of grid-tied inverters becomes an important concern for the power industry. In particular, a weak grid can lead to voltage fluctuations at the inverter terminals and consequently cause inverter instability. In this paper, impac...

  10. High Voltage Seismic Generator

    Science.gov (United States)

    Bogacz, Adrian; Pala, Damian; Knafel, Marcin

    2015-04-01

    This contribution describes the preliminary result of annual cooperation of three student research groups from AGH UST in Krakow, Poland. The aim of this cooperation was to develop and construct a high voltage seismic wave generator. Constructed device uses a high-energy electrical discharge to generate seismic wave in ground. This type of device can be applied in several different methods of seismic measurement, but because of its limited power it is mainly dedicated for engineering geophysics. The source operates on a basic physical principles. The energy is stored in capacitor bank, which is charged by two stage low to high voltage converter. Stored energy is then released in very short time through high voltage thyristor in spark gap. The whole appliance is powered from li-ion battery and controlled by ATmega microcontroller. It is possible to construct larger and more powerful device. In this contribution the structure of device with technical specifications is resented. As a part of the investigation the prototype was built and series of experiments conducted. System parameter was measured, on this basis specification of elements for the final device were chosen. First stage of the project was successful. It was possible to efficiently generate seismic waves with constructed device. Then the field test was conducted. Spark gap wasplaced in shallowborehole(0.5 m) filled with salt water. Geophones were placed on the ground in straight line. The comparison of signal registered with hammer source and sparker source was made. The results of the test measurements are presented and discussed. Analysis of the collected data shows that characteristic of generated seismic signal is very promising, thus confirms possibility of practical application of the new high voltage generator. The biggest advantage of presented device after signal characteristics is its size which is 0.5 x 0.25 x 0.2 m and weight approximately 7 kg. This features with small li-ion battery makes

  11. Low voltage arc formation in railguns

    Science.gov (United States)

    Hawke, R.S.

    1985-08-05

    A low voltage plasma arc is first established across the rails behind the projectile by switching a low voltage high current source across the rails to establish a plasma arc by vaporizing a fuse mounted on the back of the projectile, maintaining the voltage across the rails below the railgun breakdown voltage to prevent arc formation ahead of the projectile. After the plasma arc has been formed behind the projectile a discriminator switches the full energy bank across the rails to accelerate the projectile. A gas gun injector may be utilized to inject a projectile into the breech of a railgun. The invention permits the use of a gas gun or gun powder injector and an evacuated barrel without the risk of spurious arc formation in front of the projectile.

  12. Analysis of dc-Link Voltage Switching Ripple in Three-Phase PWM Inverters

    Directory of Open Access Journals (Sweden)

    Marija Vujacic

    2018-02-01

    Full Text Available The three-phase voltage source inverter (VSI is de facto standard in power conversion systems. To realize high power density systems, one of the items to be correctly addressed is the design and selection of the dc-link capacitor in relation to the voltage switching ripple. In this paper, effective formulas for designing the dc-link capacitor as a function of the switching voltage ripple amplitude are obtained, considering the operating conditions such as the modulation index and the output current amplitude. The calculations are obtained considering the requirements and restrictions referring to the high (switching-frequency dc-link voltage ripple component. Analyses have been performed considering the dc source impedance (non-ideal dc voltage source at the switching frequency and a balanced load. Analytical expressions are derived for the dc-link voltage switching ripple amplitude and its maximum value over the fundamental period. Different values of modulation index and output phase angle have been considered and different diagrams are presented. Analytical results were validated both by simulations and comprehensive experimental tests.

  13. Performance Comparison of Grid-Faulty Control Schemes for Inverter-Based Industrial Microgrids

    Directory of Open Access Journals (Sweden)

    Antonio Camacho

    2017-12-01

    Full Text Available Several control schemes specifically designed to operate inverter-based industrial microgrids during voltage sags have been recently proposed. This paper first classifies these control schemes in three categories and then performs a comparative analysis of them. Representative control schemes of each category are selected, described and used to identify the main features and performance of the considered category. The comparison is based on the evaluation of several indexes, which measure the power quality of the installation and utility grid during voltage sags, including voltage regulation, reactive current injection and transient response. The paper includes selected simulation results from a 500 kVA industrial microgrid to validate the expected features of the considered control schemes. Finally, in view of the obtained results, the paper proposes an alternative solution to cope with voltage sags, which includes the use of a static compensator in parallel with the microgrid. The novelty of this proposal is the suitable selection of the control schemes for both the microgrid and the static compensator. The superior performance of the proposal is confirmed by the analysis of the quality indexes. Its practical limitations are also revealed, showing that the topic studied in this paper is still open for further research.

  14. Miniature x-ray source

    Science.gov (United States)

    Trebes, James E.; Bell, Perry M.; Robinson, Ronald B.

    2000-01-01

    A miniature x-ray source utilizing a hot filament cathode. The source has a millimeter scale size and is capable of producing broad spectrum x-ray emission over a wide range of x-ray energies. The miniature source consists of a compact vacuum tube assembly containing the hot filament cathode, an anode, a high voltage feedthru for delivering high voltage to the cathode, a getter for maintaining high vacuum, a connector for initial vacuum pump down and crimp-off, and a high voltage connection for attaching a compact high voltage cable to the high voltage feedthru. At least a portion of the vacuum tube wall is fabricated from highly x-ray transparent materials, such as sapphire, diamond, or boron nitride.

  15. A comparison of medium voltage static transfer switches and medium voltage mechanical transfer switches

    Energy Technology Data Exchange (ETDEWEB)

    Risko, W. P.

    2002-07-01

    Medium voltage static transfer switches (MVSTS) and medium voltage mechanical transfer switches (MVATS) perform a common function, namely selecting between two independent power sources to provide uninterrupted power to the loads. Although the functions are the same the method of performing that function is different and this method impacts the sources and connected load. This article describes the two methods of transfer -- mechanical and static -- their advantages and disadvantages, and their preferred applications. The MVSTS can be incorporated into many applications; it can work in conjunction with backup sources such as generators; and can replace generators as a low cost solution. The reliability of the MVSTS is very high; it also outperforms the MVATS with regard to transfer speed, and can react to anomalies in the same sub-cycle time frame. Because the design of the MVSTS is modular, it can be engineered and designed to fit into existing and future systems and applications, and can be used with different switchgear variations and protection arrangements. For example, load isolation and protection breakers can be added to the switchgear to provide flexibility and isolation.

  16. A New Control Strategy Based Multi Converter UPQC Using Fuzzy Logic Controller to Improve the Power Quality Issues

    Directory of Open Access Journals (Sweden)

    Chandra Babu Paduchuri

    2014-01-01

    Full Text Available A design of multiconverter unified power quality conditioner to improve the power quality issues is presents in this paper. Modified SRF theory and fuzzy logic controller technique are incorporated in this modelling. This newly designed controller is connected to a source in order to compensate voltage and current in the two feeders. The expanded concept of UPQC is multi converter-UPQC; this system has two series voltage source converter (VSC and one shunt VSC connected back to back. In the proposed system, the power can be conveyed from one feeder to another in order to mitigate the voltage sag, swell, interruption and transient response of the system. The control strategies of multi converter-UPQC are designed based on the modified synchronous reference frame theory with fuzzy logic controller. The transient response of the fuzzy logic controller in dc-link voltage controller will be very fast. The relevant simulation and compensation performance analysis of multi converter-UPQC with fuzzy logic controller is performed using MATLAB/Simulink software.

  17. Effects of Electrode Material on the Voltage of a Tree-Based Energy Generator.

    Directory of Open Access Journals (Sweden)

    Zhibin Hao

    Full Text Available The voltage between a standing tree and its surrounding soil is regarded as an innovative renewable energy source. This source is expected to provide a new power generation system for the low-power electrical equipment used in forestry. However, the voltage is weak, which has caused great difficulty in application. Consequently, the development of a method to increase the voltage is a key issue that must be addressed in this area of applied research. As the front-end component for energy harvesting, a metal electrode has a material effect on the level and stability of the voltage obtained. This study aimed to preliminarily ascertain the rules and mechanisms that underlie the effects of electrode material on voltage. Electrodes of different materials were used to measure the tree-source voltage, and the data were employed in a comparative analysis. The results indicate that the conductivity of the metal electrode significantly affects the contact resistance of the electrode-soil and electrode-trunk contact surfaces, thereby influencing the voltage level. The metal reactivity of the electrode has no significant effect on the voltage. However, passivation of the electrode materials markedly reduces the voltage. Suitable electrode materials are demonstrated and recommended.

  18. Prospectively ECG-triggered high-pitch coronary angiography with third-generation dual-source CT at 70 kVp tube voltage: feasibility, image quality, radiation dose, and effect of iterative reconstruction.

    Science.gov (United States)

    Hell, Michaela M; Bittner, Daniel; Schuhbaeck, Annika; Muschiol, Gerd; Brand, Michael; Lell, Michael; Uder, Michael; Achenbach, Stephan; Marwan, Mohamed

    2014-01-01

    Low tube voltage reduces radiation exposure in coronary CT angiography (CTA). Using 70 kVp tube potential has so far not been possible because CT systems were unable to provide sufficiently high tube current with low voltage. We evaluated feasibility, image quality (IQ), and radiation dose of coronary CTA using a third-generation dual-source CT system capable of producing 450 mAs tube current at 70 kVp tube voltage. Coronary CTA was performed in 26 consecutive patients with suspected coronary artery disease, selected for body weight Image noise was lower in IR vs FBP (60 ± 10 HU vs 74 ± 8 HU; P < .001). In patients <100 kg and with a regular heart rate <60 beats/min, third-generation dual-source CT using high-pitch spiral acquisition and 70 kVp tube voltage is feasible and provides both robust IQ and very low radiation exposure. Copyright © 2014 Society of Cardiovascular Computed Tomography. Published by Elsevier Inc. All rights reserved.

  19. Dynamic Performance Evaluation of PV Integration

    Science.gov (United States)

    Gao, Ruilin; Jiang, Anwen; Chen, Hongjin

    2018-03-01

    Topics on adaptability of Grid-connected photovoltaic systems (GCPVS) under sag conditions has been proposed. A basic low-voltage-ride-through (LVRT) strategy widely used in engineering practice is taken in this paper and manages to ride through different sag conditions. The role of hardware protection has been discussed in detail. By simulation validated that the proposed GCPVS have strong adaptability

  20. Power conditioning system for energy sources

    Science.gov (United States)

    Mazumder, Sudip K [Chicago, IL; Burra, Rajni K [Chicago, IL; Acharya, Kaustuva [Chicago, IL

    2008-05-13

    Apparatus for conditioning power generated by an energy source includes an inverter for converting a DC input voltage from the energy source to a square wave AC output voltage, and a converter for converting the AC output voltage from the inverter to a sine wave AC output voltage.

  1. Passivity-based design of robust passive damping for LCL-filtered voltage source converters

    DEFF Research Database (Denmark)

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

    2015-01-01

    Passive damping is proven as a robust stabilizing technique for LCL-filtered voltage source converters. However, conventional design methods of passive dampers are based on the passive components only, while the inherent damping effect of time delay in the digital control system is overlooked....... In this paper, a frequency-domain passivity-based design approach is proposed, where the passive dampers are designed to eliminate the negative real part of the converter output admittance with closed-loop current control, rather than shaping the LCL-filter itself. Thus, the influence of time delay...... in the current control is included, which allows a relaxed design of the passive damper with the reduced power loss and improved stability robustness against grid parameters variations. Design procedures of two commonly used passive dampers with LCL-filtered VSCs are illustrated. Experimental results validate...

  2. A Series-LC-Filtered Active Trap Filter for High Power Voltage Source Inverter

    DEFF Research Database (Denmark)

    Bai, Haofeng; Wang, Xiongfei; Loh, Poh Chiang

    2016-01-01

    Passive trap filters are widely used in high power Voltage Source Inverters (VSI) for the switching harmonic attenuation. The usage of the passive trap filters requires clustered and fixed switching harmonic spectrum, which is not the case for low pulse-ratio or Variable Switching Frequency (VSF...... current control of the auxiliary converter, which can be challenging considering that the switching harmonics have very high orders. In this paper, an Active Trap Filter (ATF) based on output impedance shaping is proposed. It is able to bypass the switching harmonics by providing nearly zero output...... impedance. A series-LC-filter is used to reduce the power rating and synthesize the desired output impedance of the ATF. Compared with the existing approaches, the compensated frequency range is greatly enlarged. Also, the current reference is simply set to zero, which reduces the complexity of the control...

  3. A Unified Impedance Model of Voltage-Source Converters with Phase-Locked Loop Effect

    DEFF Research Database (Denmark)

    Wang, Xiongfei; Harnefors, Lennart; Blaabjerg, Frede

    2016-01-01

    This paper proposes a unified impedance model for analyzing the effect of Phase-Locked Loop (PLL) on the stability of grid-connected voltage-source converters. In the approach, the dq-frame impedance model is transformed into the stationary αβ-frame by means of complex transfer functions...... and complex space vectors, which not only predicts the stability impact of the PLL, but reveals also its frequency coupling effect in the phase domain. Thus, the impedance models previously developed in the different domains can be unified. Moreover, the impedance shaping effects of PLL are structurally...... characterized for the current control in the rotating dq-frame and the stationary αβ-frame. Case studies based on the unified impedance model are presented, which are then verified in the time-domain simulations and experiments. The results closely correlate with the impedance-based analysis....

  4. Improved control system of the thyristor flicker suppressor for the KEK 12-GeV PS

    International Nuclear Information System (INIS)

    Matsumoto, S.; Baba, H.; Mikawa, K.; Sato, H.; Sueno, T.

    1983-01-01

    Thyristor control system of the 20 MVar flicker suppressor has been improved essentially. The previous feed forward (FF) loop with each single phase reactive current detector of the MR magnet power supply was exchanged to the present by both FF- and NFB-loops. The FF-loops consists of a three phase reactive power detector of the MPS and a forcing pattern generator on the fast but steady line voltage flicker, sag and surge. The NFB-loops control by the slow parts of the flicker and the unbalanced line voltages. These detectors of the reactive power, the voltage flicker and the unbalance have been developed. Sampled voltage flicker data with 12 bit ADC are processed by Z-80A micro computer system and the forcing pattern is generated by the system through 12 bit DAC into the loop. A typical voltage flicker including sag and surge has been reduced within + or - 1.5%, about 1/3 compared to the previous, at 66 kV primary line

  5. The desing study of high voltage plasma focus for a large fluence neutron source by using a water capacitor bank

    International Nuclear Information System (INIS)

    Ueno, Isao; Kobata, Tadasuke

    1983-01-01

    A new possibility for high intensity neutron source (HINS) would be opened by the plasma focus device if we have a high voltage capacitor bank. A scaling law of neutron yield for D-T gas discharge in plasma focus device is obtained after Imshennik, Filippov and Filippova. The resulting scaling law shows the realizability of the D-T HINS by the use of plasma focus, provided that the device is operated under a high voltage condition. Until now, it has been difficult to construct the high voltage capacitor bank of long life, for example with V 0 =300kV, C 0 =200μF and L 0 --5nH necessary in the level of HINS. It becomes possible to design this capacitor bank by using the coaxial water capacitor which has been developed for the electron and ion beam accelerator. The size of a capacitor designed for V 0 =300kV, C 0 =1μF is phi5m x 22m. Two hundred capacitors are used in parallel in order to get the 200μF. (author)

  6. Design of Two Feeder Three Phase Four Wire Distribution System Utilizing Multi Converter UPQC with Fuzzy Logic Controller

    Directory of Open Access Journals (Sweden)

    Chandra Babu Paduchuri

    2014-01-01

    Full Text Available This paper proposes the instantaneous p-q theory based fuzzy logic controller (FLC for multi converter unified power quality conditioner (MC-UPQC to mitigate power quality issues in two feeders three-phase four-wire distribution systems. The proposed system is extended system of the existing one feeder three-phase four-wire distribution system, which is operated with UPQC. This system is employed with three voltage source converters, which are connected commonly to two feeder distribution systems. The performance of this proposed system used to compensate voltage sag, neutral current mitigation and compensation of voltage and current harmonics under linear and nonlinear load conditions. The neutral current flowing in series transformers is zero in the implementation of the proposed system. The simulation performance analysis is carried out using MATLAB.

  7. Multi-Objective Scheduling Optimization Based on a Modified Non-Dominated Sorting Genetic Algorithm-II in Voltage Source Converter−Multi-Terminal High Voltage DC Grid-Connected Offshore Wind Farms with Battery Energy Storage Systems

    Directory of Open Access Journals (Sweden)

    Ho-Young Kim

    2017-07-01

    Full Text Available Improving the performance of power systems has become a challenging task for system operators in an open access environment. This paper presents an optimization approach for solving the multi-objective scheduling problem using a modified non-dominated sorting genetic algorithm in a hybrid network of meshed alternating current (AC/wind farm grids. This approach considers voltage and power control modes based on multi-terminal voltage source converter high-voltage direct current (MTDC and battery energy storage systems (BESS. To enhance the hybrid network station performance, we implement an optimal process based on the battery energy storage system operational strategy for multi-objective scheduling over a 24 h demand profile. Furthermore, the proposed approach is formulated as a master problem and a set of sub-problems associated with the hybrid network station to improve the overall computational efficiency using Benders’ decomposition. Based on the results of the simulations conducted on modified institute of electrical and electronics engineers (IEEE-14 bus and IEEE-118 bus test systems, we demonstrate and confirm the applicability, effectiveness and validity of the proposed approach.

  8. Advances in high voltage engineering

    CERN Document Server

    Haddad, A

    2005-01-01

    This book addresses the very latest research and development issues in high voltage technology and is intended as a reference source for researchers and students in the field, specifically covering developments throughout the past decade. This unique blend of expert authors and comprehensive subject coverage means that this book is ideally suited as a reference source for engineers and academics in the field for years to come.

  9. 30 CFR 75.802 - Protection of high-voltage circuits extending underground.

    Science.gov (United States)

    2010-07-01

    ...-Voltage Distribution § 75.802 Protection of high-voltage circuits extending underground. (a) Except as... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Protection of high-voltage circuits extending... which shall be grounded through a suitable resistor at the source transformers, and a grounding circuit...

  10. Coordinated Voltage Control Scheme for VSC-HVDC Connected Wind Power Plants

    DEFF Research Database (Denmark)

    Guo, Yifei; Gao, Houlei; Wu, Qiuwei

    2017-01-01

    This paper proposes a coordinated voltage control scheme based on model predictive control (MPC) for voltage source converter‐based high voltage direct current (VSC‐HVDC) connected wind power plants (WPPs). In the proposed scheme, voltage regulation capabilities of VSC and WTGs are fully utilized...... and optimally coordinated. Two control modes, namely operation optimization mode and corrective mode, are designed to coordinate voltage control and economic operation of the system. In the first mode, the control objective includes the bus voltages, power losses and dynamic Var reserves of wind turbine...

  11. A cascaded three-phase symmetrical multistage voltage multiplier

    International Nuclear Information System (INIS)

    Iqbal, Shahid; Singh, G K; Besar, R; Muhammad, G

    2006-01-01

    A cascaded three-phase symmetrical multistage Cockcroft-Walton voltage multiplier (CW-VM) is proposed in this report. It consists of three single-phase symmetrical voltage multipliers, which are connected in series at their smoothing columns like string of batteries and are driven by three-phase ac power source. The smoothing column of each voltage multiplier is charged twice every cycle independently by respective oscillating columns and discharged in series through load. The charging discharging process completes six times a cycle and therefore the output voltage ripple's frequency is of sixth order of the drive signal frequency. Thus the proposed approach eliminates the first five harmonic components of load generated voltage ripples and sixth harmonic is the major ripple component. The proposed cascaded three-phase symmetrical voltage multiplier has less than half the voltage ripple, and three times larger output voltage and output power than the conventional single-phase symmetrical CW-VM. Experimental and simulation results of the laboratory prototype are given to show the feasibility of proposed cascaded three-phase symmetrical CW-VM

  12. Two methods for damping torsional vibrations in DFIG-based wind generators using power converters

    Science.gov (United States)

    Zhao, Zuyi; Lu, Yupu; Xie, Da; Yu, Songtao; Wu, Wangping

    2017-01-01

    This paper proposes novel damping control algorithms by using static synchronous compensator (STATCOM) and energy storage system (ESS) to damp torsional vibrations in doubly fed induction generator (DFIG) based wind turbine systems. It first analyses the operating characteristics of STATCOM and ESS for regulating power variations to increase grid voltage stability. Then, new control strategies for STATCOM and ESS are introduced to damp the vibrations. It is followed by illustration of their effectiveness to damp the drive train torsional vibrations of wind turbines, which can be caused by grid disturbances, such as voltage sags and frequency fluctuations. Results suggest that STATCOM is a promising technology to mitigate the torsional vibrations caused by grid voltage sags. By contrast, the ESS connected to the point of common coupling (PCC) of wind turbine systems shows even obvious advantages because of its capability of absorbing/releasing both active and reactive power. It can thus be concluded that STATCOM is useful for stabilizing power system voltage fluctuations, and ESS is more effective both in regulating PCC voltage fluctuations and damping torsional vibrations caused by grid voltage frequency fluctuations.

  13. Nested high voltage generator/particle accelerator

    International Nuclear Information System (INIS)

    Adler, R.J.

    1992-01-01

    This patent describes a modular high voltage particle accelerator having an emission axis and an emission end, the accelerator. It comprises: a plurality of high voltage generators in nested adjacency to form a nested stack, each the generator comprising a cup-like housing having a base and a tubular sleeve extending from the base, a primary transformer winding encircling the nested stack; a secondary transformer winding between each adjacent pair of housings, magnetically linked to the primary transformer winding through the gaps; a power supply respective to each of the secondary windings converting alternating voltage from its respective secondary winding to d.c. voltage, the housings at the emission end forming a hollow throat for particle acceleration, a vacuum seal at the emission end of the throat which enables the throat to be evacuated; a particle source in the thrond power means to energize the primary transformer winding

  14. Improved Passive-Damped LCL Filter to Enhance Stability in Grid-Connected Voltage-Source Converters

    DEFF Research Database (Denmark)

    Beres, Remus Narcis; Wang, Xiongfei; Blaabjerg, Frede

    2015-01-01

    This paper proposes an improved passive-damped LCL filter to be used as interface between the grid-connected voltage-source converters and the utility grid. The proposed filter replaces the LCL filter capacitor with a traditional C-type filter with the resonant circuit tuned in such a way...... passive-damped LCL filter. To verify the benefits of the proposed filter, a comparison with the conventional filter is made in terms of losses and ratings when both the filters are designed under the same condition....... that switching harmonics due to pulse width modulation are to be cancelled. Since the tuned circuit of the C-type filter suppresses the switching harmonics more effectively, the total inductance of the filter can be reduced. Additionally, the rating of the damping resistor is lower, compared with conventional...

  15. Artificial intelligence techniques for voltage control

    Energy Technology Data Exchange (ETDEWEB)

    Ekwue, A.; Cheng, D.T.Y.; Macqueen, J.F.

    1997-12-31

    In electric power systems, the advantages of reactive power dispatching or optimisation include improved utilisation of reactive power sources and hence reduction in reactive power flows and real losses of the system; unloading of the system and equipment as a result of reactive flow reduction; the power factors of generation are improved and system security is enhanced; reduced voltage gradients and somewhat higher voltages which result across the system from improved operation; deferred capital investment is new reactive power sources as a result of improved utilisation of existing equipment; and for the National Grid Company plc (NGC), the main advantage is reduced out-of-merit operation. The problem of reactive power control has been studied and widely reported in the literature. Non-linear programming methods as well as linear programming techniques for constraint dispatch have been described. Static optimisation of reactive power sources by the use of sensitivity analysis was described by Kishore and Hill. Long range optimum var planning has been considered and the optimum amount and location of network reactive compensation so as to maintain the system voltage within the desired limits, while operating under normal and various insecurity states, have also been studied using several methods. The objective of this chapter is therefore to review conventional methods as well as AI techniques for reactive power control. (Author)

  16. Subsidence transition during the post-rift stage of the Dongpu Sag, Bohai Bay Basin, NE China: A new geodynamic model

    Science.gov (United States)

    Xu, Han; Wang, Xin-Wen; Yan, Dan-Ping; Qiu, Liang

    2018-06-01

    The Dongpu Sag, located in the Bohai Bay Basin, NE China, is a Cenozoic continental rift basin. The post-rift evolution of the Dongpu Sag is associated with the development of petroleum reservoirs and has implications for Neogene-Quaternary basin evolution along the eastern margin of Eurasia. To determine the nature and origin of post-rift subsidence in the Dongpu Sag, we apply backstripping, modified strain-rate inversion, and revised finite extension modelling techniques, using data from 14 real and synthetic wells that are intersected by three seismic lines. Our results reveal discrepancies by subsidence based on backstripping of well data (the observed subsidence) minus that predicted by modified strain-rate inversion and revised finite extension modelling (the predicted subsidence). During the Miocene, the observed subsidence was smaller than the predicted subsidence, leaving negative discrepancies referred to here as "insufficient subsidence" ranging from -343 to -96 m. In contrast, during the Pliocene-Quaternary the observed subsidence was greater than the predicted subsidence by +123 to +407 m, which left positive discrepancies referred to as "over-sufficient subsidence". Therefore, we infer a transition from insufficient to over-sufficient subsidence during the post-rift stage. Normal faulting that started at ca. 5.3 Ma is estimated to have produced only ∼20% of the over-sufficient subsidence. Therefore, the remaining over-sufficient subsidence, as well as the preceding insufficient subsidence and the transition between the two, were likely controlled by lithosphere processes. We propose a new tectonic model in which variations in the conditions (e.g. rate, direction, and angle) associated with subduction of the Pacific plate resulted in a change of heat flow decreasing from a linear to a curvilinear pattern, leading to a transition from insufficient to over-sufficient subsidence.

  17. A method of accurate determination of voltage stability margin

    Energy Technology Data Exchange (ETDEWEB)

    Wiszniewski, A.; Rebizant, W. [Wroclaw Univ. of Technology, Wroclaw (Poland); Klimek, A. [AREVA Transmission and Distribution, Stafford (United Kingdom)

    2008-07-01

    In the process of developing power system disturbance, voltage instability at the receiving substations often contributes to deteriorating system stability, which eventually may lead to severe blackouts. The voltage stability margin at receiving substations may be used to determine measures to prevent voltage collapse, primarily by operating or blocking the transformer tap changing device, or by load shedding. The best measure of the stability margin is the actual load to source impedance ratio and its critical value, which is unity. This paper presented an accurate method of calculating the load to source impedance ratio, derived from the Thevenin's equivalent circuit of the system, which led to calculation of the stability margin. The paper described the calculation of the load to source impedance ratio including the supporting equations. The calculation was based on the very definition of voltage stability, which says that system stability is maintained as long as the change of power, which follows the increase of admittance is positive. The testing of the stability margin assessment method was performed in a simulative way for a number of power network structures and simulation scenarios. Results of the simulations revealed that this method is accurate and stable for all possible events occurring downstream of the device location. 3 refs., 8 figs.

  18. Diagnostic value of a Rec-ELISA using Toxoplasma gondii recombinant SporoSAG, BAG1, and GRA1 proteins in murine models infected orally with tissue cysts and oocysts.

    Directory of Open Access Journals (Sweden)

    Mert Döşkaya

    Full Text Available Toxoplasma gondii causes congenital toxoplasmosis in newborns resulting with fetal anomalies. Determining the initiation time of infection is very important for pregnant women and current serological assays have drawbacks in distinguishing the recently acute toxoplasmosis. Diagnosis of recently acute infection may be improved by using stage specific antigens in serological assays. In the present study, the diagnostic value of sporozoite specific SporoSAG, bradyzoite specific BAG1 proteins and GRA1 protein expressed by all forms of the parasite have been evaluated ELISA using sera systematically collected from mice administered orally with tissue cyst and oocysts. The anti-SporoSAG IgM antibodies in sera obtained from mice infected with oocysts peaked significantly at days 1, 10, and 15 (P<0.01. The anti-BAG1 IgM antibodies in sera obtained from mice infected with tissue cysts peaked significantly at days 15, 40, and 120 (P<0.05. The anti-GRA1 IgM antibodies in sera obtained from mice infected with oocysts peaked significantly at days 2, 10, and 40 (P<0.01. The anti-GRA1 IgM antibodies in sera obtained from mice infected with tissue cysts peaked significantly only at day 40 (P<0.05. The anti-SporoSAG, anti-BAG1, and anti-GRA1 IgG titers of mice showed significant increases at day 40 (P<0.05 and decrement started for only anti-GRA1 IgG at day 120. The presence of anti-SporoSAG IgM and IgG antibodies can be interpreted as recently acute infection between days 10-40 because IgM decreases at day 40. Similarly, presence of anti-BAG1 IgM and absence of IgG can be evaluated as a recently acute infection that occurred 40 days before because IgG peaks at day 40. A peak in anti-GRA1 antibody level at first testing and reduction in consecutive sample can be considered as an infection approximately around day 40 or prior. Overall, recombinant SporoSAG, BAG1 and GRA1 proteins can be accepted as valuable diagnostic markers of recently acute toxoplasmosis.

  19. Electron backstream to the source plasma region in an ion source

    International Nuclear Information System (INIS)

    Ohara, Y.; Akiba, M.; Arakawa, Y.; Okumura, Y.; Sakuraba, J.

    1980-01-01

    The flux of backstream electrons to the source plasma region increases significantly with the acceleration voltage of an ion beam, so that the back plate in the arc chamber should be broken for quasi-dc operation. The flux of backstream electrons is estimated at the acceleration voltage of 50--100 kV for a proton beam with the aid of ion beam simulation code. The power flux of backstream electrons is up to about 7% of the total beam output at the acceleration voltage of 75 kV. It is pointed out that the conventional ion sources such as the duoPIGatron or the bucket source which use a magnetic field for source plasma production are not suitable for quasi-dc and high-energy ion sources, because the surface heat flux of the back plate is increased by the focusing of backstream electrons and the removal of it is quite difficult. A new ion source which has an electron beam dump in the arc chamber is proposed

  20. Triple voltage dc-to-dc converter and method

    Science.gov (United States)

    Su, Gui-Jia

    2008-08-05

    A circuit and method of providing three dc voltage buses and transforming power between a low voltage dc converter and a high voltage dc converter, by coupling a primary dc power circuit and a secondary dc power circuit through an isolation transformer; providing the gating signals to power semiconductor switches in the primary and secondary circuits to control power flow between the primary and secondary circuits and by controlling a phase shift between the primary voltage and the secondary voltage. The primary dc power circuit and the secondary dc power circuit each further comprising at least two tank capacitances arranged in series as a tank leg, at least two resonant switching devices arranged in series with each other and arranged in parallel with the tank leg, and at least one voltage source arranged in parallel with the tank leg and the resonant switching devices, said resonant switching devices including power semiconductor switches that are operated by gating signals. Additional embodiments having a center-tapped battery on the low voltage side and a plurality of modules on both the low voltage side and the high voltage side are also disclosed for the purpose of reducing ripple current and for reducing the size of the components.

  1. A pre-Paleogene unconformity surface of the Sikeshu Sag, Junggar Basin: Lithological, geophysical and geochemical implications for the transportation of hydrocarbons

    Directory of Open Access Journals (Sweden)

    Xiaoyue Gao

    2013-11-01

    Full Text Available The unconformity surface at the bottom of the Paleogene is one of the most important migration pathways in the Sikeshu Sag of the Junggar Basin, which consists of three layers: upper coarse clastic rock, lower weathering crust and leached zone. The upper coarse clastic rock is characterized by higher density and lower SDT and gamma-ray logging parameters, while the lower weathering crust displays opposite features. The transport coefficient of the unconformity surface is controlled by its position in respect to the basal sandstone; it is higher in the ramp region but lower in the adjacent uplifted and sag areas. The content of saturated hydrocarbons increases with the decrease of the content of non-hydrocarbons and asphaltenes. The content of benzo[c] carbazole decreases as the content of benzo[a] carbazole and [alkyl carbazole]/[alkyl + benzo carbazole] increases. This suggests that the unconformity surface is an efficient medium for the transportation of hydrocarbons.

  2. On the theory of non-self-maintained low voltage arc discharge

    International Nuclear Information System (INIS)

    Shcherbinin, P.P.; Cherednichenko, Yu.G.

    1980-01-01

    In the approximation of constant temperature of plasma electrons for two emitter temperatures 1440 and 1830 K calculated are the volt-ampere characteristics and components of the voltage internal drop in a thermionic converter in the cases of self-maintained discharge in cesium and with an external source of atom ionization and electron heating. It is obtained, that using an external ionization source the decrease of voltage drop in the interelectrode gap with account of ionization energy constitutes about 0.1 V. Electron heating is not effective. For further reduction of voltage losses it is necessary to search for ways for decreasing electron Coulomb scattering on ions

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

    Directory of Open Access Journals (Sweden)

    Ufa Ruslan A.

    2014-01-01

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

  4. Analysis and design of grid-current-feedback active damping for LCL resonance in grid-connected voltage source converters

    DEFF Research Database (Denmark)

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

    2014-01-01

    This paper investigates the active damping of LCL-filter resonance within single-loop grid current control of grid-connected voltage source converters. First, the basic analysis in the continuous s-domain reveals that the grid-current-feedback active damping forms a virtual impedance across...... in a digital control system. The instability induced by the negative virtual resistance, which is commonly experienced in the feedback-type active damping, can thus be avoided. A systematic design method of the highpass filter is also proposed by the help of root locus analysis in the discrete z-domain. Lastly...

  5. Voltage-dependent gating of hERG potassium channels

    Directory of Open Access Journals (Sweden)

    Yen May eCheng

    2012-05-01

    Full Text Available The mechanisms by which voltage-gated channels sense changes in membrane voltage and energetically couple this with opening of the ion conducting pore has been the source of significant interest. In voltage-gated potassium (Kv channels, much of our knowledge in this area comes from Shaker-type channels, for which voltage-dependent gating is quite rapid. In these channels, activation and deactivation are associated with rapid reconfiguration of the voltage-sensing domain unit that is electromechanically coupled, via the S4-S5 linker helix, to the rate-limiting opening of an intracellular pore gate. However, fast voltage-dependent gating kinetics are not typical of all Kv channels, such as Kv11.1 (human ether-a-go-go related gene, hERG, which activates and deactivates very slowly. Compared to Shaker channels, our understanding of the mechanisms underlying slow hERG gating is much poorer. Here, we present a comparative review of the structure-function relationships underlying voltage-dependent gating in Shaker and hERG channels, with a focus on the roles of the voltage sensing domain and the S4-S5 linker that couples voltage sensor movements to the pore. Measurements of gating current kinetics and fluorimetric analysis of voltage sensor movement are consistent with models suggesting that the hERG activation pathway contains a voltage independent step, which limits voltage sensor transitions. Constraints upon hERG voltage sensor movement may result from loose packing of the S4 helices and additional intra-voltage sensor counter charge interactions. More recent data suggest that key amino acid differences in the hERG voltage sensing unit and S4-S5 linker, relative to fast activating Shaker-type Kv channels, may also contribute to the increased stability of the resting state of the voltage sensor.

  6. Voltage-Dependent Gating of hERG Potassium Channels

    Science.gov (United States)

    Cheng, Yen May; Claydon, Tom W.

    2012-01-01

    The mechanisms by which voltage-gated channels sense changes in membrane voltage and energetically couple this with opening of the ion conducting pore has been the source of significant interest. In voltage-gated potassium (Kv) channels, much of our knowledge in this area comes from Shaker-type channels, for which voltage-dependent gating is quite rapid. In these channels, activation and deactivation are associated with rapid reconfiguration of the voltage-sensing domain unit that is electromechanically coupled, via the S4–S5 linker helix, to the rate-limiting opening of an intracellular pore gate. However, fast voltage-dependent gating kinetics are not typical of all Kv channels, such as Kv11.1 (human ether-à-go-go related gene, hERG), which activates and deactivates very slowly. Compared to Shaker channels, our understanding of the mechanisms underlying slow hERG gating is much poorer. Here, we present a comparative review of the structure–function relationships underlying activation and deactivation gating in Shaker and hERG channels, with a focus on the roles of the voltage-sensing domain and the S4–S5 linker that couples voltage sensor movements to the pore. Measurements of gating current kinetics and fluorimetric analysis of voltage sensor movement are consistent with models suggesting that the hERG activation pathway contains a voltage independent step, which limits voltage sensor transitions. Constraints upon hERG voltage sensor movement may result from loose packing of the S4 helices and additional intra-voltage sensor counter-charge interactions. More recent data suggest that key amino acid differences in the hERG voltage-sensing unit and S4–S5 linker, relative to fast activating Shaker-type Kv channels, may also contribute to the increased stability of the resting state of the voltage sensor. PMID:22586397

  7. The eGo grid model: An open source approach towards a model of German high and extra-high voltage power grids

    Science.gov (United States)

    Mueller, Ulf Philipp; Wienholt, Lukas; Kleinhans, David; Cussmann, Ilka; Bunke, Wolf-Dieter; Pleßmann, Guido; Wendiggensen, Jochen

    2018-02-01

    There are several power grid modelling approaches suitable for simulations in the field of power grid planning. The restrictive policies of grid operators, regulators and research institutes concerning their original data and models lead to an increased interest in open source approaches of grid models based on open data. By including all voltage levels between 60 kV (high voltage) and 380kV (extra high voltage), we dissolve the common distinction between transmission and distribution grid in energy system models and utilize a single, integrated model instead. An open data set for primarily Germany, which can be used for non-linear, linear and linear-optimal power flow methods, was developed. This data set consists of an electrically parameterised grid topology as well as allocated generation and demand characteristics for present and future scenarios at high spatial and temporal resolution. The usability of the grid model was demonstrated by the performance of exemplary power flow optimizations. Based on a marginal cost driven power plant dispatch, being subject to grid restrictions, congested power lines were identified. Continuous validation of the model is nescessary in order to reliably model storage and grid expansion in progressing research.

  8. Power Quality Improvement by Unified Power Quality Conditioner Based on CSC Topology Using Synchronous Reference Frame Theory

    Directory of Open Access Journals (Sweden)

    Rajasekaran Dharmalingam

    2014-01-01

    Full Text Available This paper deals with the performance of unified power quality conditioner (UPQC based on current source converter (CSC topology. UPQC is used to mitigate the power quality problems like harmonics and sag. The shunt and series active filter performs the simultaneous elimination of current and voltage problems. The power fed is linked through common DC link and maintains constant real power exchange. The DC link is connected through the reactor. The real power supply is given by the photovoltaic system for the compensation of power quality problems. The reference current and voltage generation for shunt and series converter is based on phase locked loop and synchronous reference frame theory. The proposed UPQC-CSC design has superior performance for mitigating the power quality problems.

  9. Power quality improvement by unified power quality conditioner based on CSC topology using synchronous reference frame theory.

    Science.gov (United States)

    Dharmalingam, Rajasekaran; Dash, Subhransu Sekhar; Senthilnathan, Karthikrajan; Mayilvaganan, Arun Bhaskar; Chinnamuthu, Subramani

    2014-01-01

    This paper deals with the performance of unified power quality conditioner (UPQC) based on current source converter (CSC) topology. UPQC is used to mitigate the power quality problems like harmonics and sag. The shunt and series active filter performs the simultaneous elimination of current and voltage problems. The power fed is linked through common DC link and maintains constant real power exchange. The DC link is connected through the reactor. The real power supply is given by the photovoltaic system for the compensation of power quality problems. The reference current and voltage generation for shunt and series converter is based on phase locked loop and synchronous reference frame theory. The proposed UPQC-CSC design has superior performance for mitigating the power quality problems.

  10. Power Quality Improvement by Unified Power Quality Conditioner Based on CSC Topology Using Synchronous Reference Frame Theory

    Science.gov (United States)

    Dharmalingam, Rajasekaran; Dash, Subhransu Sekhar; Senthilnathan, Karthikrajan; Mayilvaganan, Arun Bhaskar; Chinnamuthu, Subramani

    2014-01-01

    This paper deals with the performance of unified power quality conditioner (UPQC) based on current source converter (CSC) topology. UPQC is used to mitigate the power quality problems like harmonics and sag. The shunt and series active filter performs the simultaneous elimination of current and voltage problems. The power fed is linked through common DC link and maintains constant real power exchange. The DC link is connected through the reactor. The real power supply is given by the photovoltaic system for the compensation of power quality problems. The reference current and voltage generation for shunt and series converter is based on phase locked loop and synchronous reference frame theory. The proposed UPQC-CSC design has superior performance for mitigating the power quality problems. PMID:25013854

  11. Synchronization of grid-connected renewable energy sources under highly distorted voltages and unbalanced grid faults

    DEFF Research Database (Denmark)

    Hadjidemetriou, Lenos; Kyriakides, Elias; Blaabjerg, Frede

    2013-01-01

    Renewable energy sources require accurate and appropriate performance not only under normal grid operation but also under abnormal and faulty grid conditions according to the modern grid codes. This paper proposes a novel phase-locked loop algorithm (MSHDC-PLL), which can enable the fast...... and dynamic synchronization of the interconnected renewable energy system under unbalanced grid faults and under highly harmonic distorted voltage. The outstanding performance of the suggested PLL is achieved by implementing an innovative multi-sequence/harmonic decoupling cell in order to dynamically cancel...... renewable energy systems. Therefore, the performance of the new PLL can increase the quality of the injected power under abnormal conditions and in addition enable the renewable energy systems to provide the appropriate support to the grid under balanced and unbalanced grid faults....

  12. Voltage Flicker Mitigation in Electric Arc Furnace using D-STATCOM

    OpenAIRE

    Deepthisree Madathil; Ilango Karuppasamy; Kirthika Devi V S; Manjula G Nair

    2014-01-01

    The major power quality issue of voltage flicker has resulted as a serious concern for the customers and heavy power companies. Voltage flicker is an impression of unsteadiness of visual sensation induced by a light source whose luminance fluctuates with time. This phenomenon is experienced when an Electric Arc Furnace (EAF) as load is connected to the power system. Flexible AC transmission devices (FACTS) devices were gradually utilized for voltage flicker reduction. In this paper the FACTS ...

  13. Enhanced current and voltage regulators for stand-alone applications

    DEFF Research Database (Denmark)

    Federico, de Bosio; Pastorelli, Michele; Antonio DeSouza Ribeiro, Luiz

    2016-01-01

    State feedback decoupling permits to achieve a better dynamic response for Voltage Source in stand-alone applications. The design of current and voltage regulators is performed in the discrete-time domain since it provides better accuracy and allows direct pole placement. As the attainable...... bandwidth of the current loop is mainly limited by computational and PWM delays, a lead compensator structure is proposed to overcome this limitation. The design of the voltage regulator is based on the Nyquist criterion, verifying to guarantee a high sensitivity peak. Discrete-time domain implementation...

  14. Sag compensation system for assembly of MDT-chambers for the ATLAS experiment

    International Nuclear Information System (INIS)

    Barashkov, A.V.; Glonti, G.L.; Gongadze, A.L.; Evtukhovich, P.G.; Il'yushenko, E.N.; Kotov, S.A.; Kruchonok, V.G.; Tskhadadze, Eh.G.; Chepurnov, V.F.; Shelkov, G.A.

    2005-01-01

    The description of a system of the devices created for compensation of the gravitational deflection of the drift chamber during its assembly is presented. By means of this system during stage-by-stage gluing of layers of tube drift detectors to the chamber the transversal deflection considerably decreases and by that high accuracy of mutual position of separate tubes is provided. The devices were applied at assembly of 74 MDT-chambers of the ATLAS experiment. Design values of deformation of the chambers as well as the results of measurement of transversal deflections obtained during the assembly with the use of the system of sag compensation are given. Testing of chambers on the X-ray tomograph at CERN has shown that the accuracy of the positions of separate signal wires inside the assembled chambers is within the limits of the required 20 μm

  15. Design & Fabrication of a High-Voltage Photovoltaic Cell

    Energy Technology Data Exchange (ETDEWEB)

    Felder, Jennifer; /North Carolina State U. /SLAC

    2012-09-05

    Silicon photovoltaic (PV) cells are alternative energy sources that are important in sustainable power generation. Currently, applications of PV cells are limited by the low output voltage and somewhat low efficiency of such devices. In light of this fact, this project investigates the possibility of fabricating high-voltage PV cells on float-zone silicon wafers having output voltages ranging from 50 V to 2000 V. Three designs with different geometries of diffusion layers were simulated and compared in terms of metal coverage, recombination, built-in potential, and conduction current density. One design was then chosen and optimized to be implemented in the final device design. The results of the simulation serve as a feasibility test for the design concept and provide supportive evidence of the effectiveness of silicon PV cells as high-voltage power supplies.

  16. Improved model predictive control for high voltage quality in microgrid applications

    DEFF Research Database (Denmark)

    Dragicevic, T.; Al hasheem, Mohamed; Lu, M.

    2017-01-01

    This paper proposes an improvement of the finite control set model predictive control (FCS-MPC) strategy for enhancing the voltage regulation performance of a voltage source converter (VSC) used for standalone microgrid and uninterrupted power supply (UPS) applications. The modification is based...

  17. Design and test of component circuits of an integrated quantum voltage noise source for Johnson noise thermometry

    Science.gov (United States)

    Yamada, Takahiro; Maezawa, Masaaki; Urano, Chiharu

    2015-11-01

    We present design and testing of a pseudo-random number generator (PRNG) and a variable pulse number multiplier (VPNM) which are digital circuit subsystems in an integrated quantum voltage noise source for Jonson noise thermometry. Well-defined, calculable pseudo-random patterns of single flux quantum pulses are synthesized with the PRNG and multiplied digitally with the VPNM. The circuit implementation on rapid single flux quantum technology required practical circuit scales and bias currents, 279 junctions and 33 mA for the PRNG, and 1677 junctions and 218 mA for the VPNM. We confirmed the circuit operation with sufficiently wide margins, 80-120%, with respect to the designed bias currents.

  18. New non-linear control strategy for non-isolated DC/DC converter with high voltage ratio

    Energy Technology Data Exchange (ETDEWEB)

    Shahin, A.; Huang, B.; Martin, J.P.; Pierfederici, S.; Davat, B. [Groupe de Recherche en Electronique et en Electrotechnique de Nancy - INPL - Nancy Universite, 2, Avenue de la Foret de Haye, 54516 Vandoeuvre-les-Nancy Cedex (France)

    2010-01-15

    In this paper, a non-isolated DC/DC converter with high voltage ratio is proposed to allow the interface between a low voltage power source like fuel cell and a high voltage DC bus. To take into account the low voltage-high density characteristics of power sources, a cascaded structure composed of two sub-converters has been chosen and allows obtaining a high voltage ratio. The choice of each sub-converter is based on the requirements of the source and its performances. Consequently, we have chosen a three-interleaved boost converter as the 1st sub-converter whereas the 2nd sub-converter is a three-level boost converter. The control of the whole system is realized thanks to energetic trajectories planning based on flatness properties of the system. The control of both the current and the balance of voltage across the output serial capacitors of the three-level boost converter is ensured by non-linear controllers based on a new non-linear model. Experimental results allow validating the proposed power architecture and its associated control. (author)

  19. New non-linear control strategy for non-isolated DC/DC converter with high voltage ratio

    International Nuclear Information System (INIS)

    Shahin, A.; Huang, B.; Martin, J.P.; Pierfederici, S.; Davat, B.

    2010-01-01

    In this paper, a non-isolated DC/DC converter with high voltage ratio is proposed to allow the interface between a low voltage power source like fuel cell and a high voltage DC bus. To take into account the low voltage-high density characteristics of power sources, a cascaded structure composed of two sub-converters has been chosen and allows obtaining a high voltage ratio. The choice of each sub-converter is based on the requirements of the source and its performances. Consequently, we have chosen a three-interleaved boost converter as the 1st sub-converter whereas the 2nd sub-converter is a three-level boost converter. The control of the whole system is realized thanks to energetic trajectories planning based on flatness properties of the system. The control of both the current and the balance of voltage across the output serial capacitors of the three-level boost converter is ensured by non-linear controllers based on a new non-linear model. Experimental results allow validating the proposed power architecture and its associated control.

  20. Coordinated Voltage Control of Distributed PV Inverters for Voltage Regulation in Low Voltage Distribution Networks

    DEFF Research Database (Denmark)

    Nainar, Karthikeyan; Pokhrel, Basanta Raj; Pillai, Jayakrishnan Radhakrishna

    2017-01-01

    This paper reviews and analyzes the existing voltage control methods of distributed solar PV inverters to improve the voltage regulation and thereby the hosting capacity of a low-voltage distribution network. A novel coordinated voltage control method is proposed based on voltage sensitivity...... optimization. The proposed method is used to calculate the voltage bands and droop settings of PV inverters at each node by the supervisory controller. The local controller of each PV inverter implements the volt/var control and if necessary, the active power curtailment as per the received settings and based...... on measured local voltages. The advantage of the proposed method is that the calculated reactive power and active power droop settings enable fair contribution of the PV inverters at each node to the voltage regulation. Simulation studies are conducted using DigSilent Power factory software on a simplified...

  1. Geochemical characteristics of crude oil from a tight oil reservoir in the Lucaogou Formation, Jimusar Sag, Junggar Basin

    Science.gov (United States)

    Cao, Z.

    2015-12-01

    Jimusar Sag, which lies in the Junggar Basin,is one of the most typical tight oil study areas in China. However, the properties and origin of the crude oil and the geochemical characteristics of the tight oil from the Lucaogou Formation have not yet been studied. In the present study, 23 crude oilsfrom the Lucaogou Formation were collected for analysis, such as physical properties, bulk composition, saturated hydrocarbon gas chromatography-mass spectrometry (GC-MS), and the calculation of various biomarker parameters. In addition,source rock evaluation and porosity permeability analysis were applied to the mudstones and siltstones. Biomarkers of suitable source rocks (TOC>1, S1+S2>6mg/g, 0.7%source correlation. To analyze the hydrocarbon generation history of the Lucaogou source rock, 1D basin modeling was performed. The oil-filling history was also defined by means of basin modeling and microthermometry. The results indicated the presence of low maturity to mature crude oils originating from the burial of terrigenous organic matter beneath a saline lake in the source rocks of mainly type II1kerogen. In addition, a higher proportion of bacteria and algae was shown to contribute to the formation of crude oil in the lower section when compared with the upper section of the Lucaogou Formation. Oil-source correlations demonstrated that not all mudstones within the Lucaogou Formation contributed to oil accumulation.Crude oil from the upper and lower sections originated from thin-bedded mudstones interbedded within sweet spot sand bodies. A good coincidence of filling history and hydrocarbon generation history indicated that the Lucaogou reservoir is a typical in situ reservoir. The mudstones over or beneath the sweet spot bodies consisted of natural caprocks and prevented the vertical movement of oil by capillary forces. Despite being thicker, the thick-bedded mudstone between the upper and lower sweet spots had no obvious contribution to

  2. Six transformer based asymmetrical embedded Z-source inverters

    DEFF Research Database (Denmark)

    Wei, Mo; Poh Chiang, Loh; Chi, Jin

    2013-01-01

    Embedded/Asymmetrical embedded Z-source inverters were proposed to maintain smooth input current/voltage across the dc source and within the impedance network, remain the shoot-through feature used to boost up the dc-link voltage without adding bulky filter at input side. This paper introduces a ...... a class of transformer based asymmetrical embedded Z-source inverters which keep the smooth input current and voltage while achieving enhanced voltage boost capability. The presented inverters are verified by laboratory prototypes experimentally....

  3. An inverted-geometry, high voltage polarized electron gun with UHV load lock

    International Nuclear Information System (INIS)

    Breidenbach, M.; Foss, M.; Hodgson, J.; Kulikov, A.; Odian, A.; Putallaz, G.; Rogers, H.; Schindler, R.; Skarpaas, K.; Zolotorev, M.

    1994-01-01

    The design of a high voltage electron source with a GaAs photocathode and a load lock system is described. The inverted high voltage structure of the gun permits a compact and simple design. Test results demonstrate that the load lock system provides a reliable way to achieve high quantum efficiency of the photocathode in a high voltage device. ((orig.))

  4. Propagation of disturbances as voltage fluctuations in transmission networks

    Directory of Open Access Journals (Sweden)

    Albert Hermina

    2016-08-01

    Full Text Available Significant changes occurred in the power system in Romania in recent years by reducing the power used in the system, the number of classic power sources in operation as well as by implementing renewable energy sources, have determined short circuit power reduction (node rigidity in the points where disturbing users are connected, that in the absence of adequate measures, result in disturbances above acceptable levels. The paper analyzes two power systems areas in which are connected users that cause voltage fluctuation. Disturbances as voltage fluctuations resulting in these nodes may exceed the acceptable values and can spread in the transmission network affecting power quality over large system areas. The analysis conducted reveals the influence of short circuit power in nodes where these users are connected and highlights the fact that in some cases (e.g. lines out of operation for maintenance, shutdown of classic units in the area the disturbances in the transmission network sent to the users at lower voltages may have values above those allowed. Technical Code of existing power transmission network makes no reference to voltage fluctuations, as a rule, in the electricity transmission network was considered that this phenomenon should not exist.

  5. A new analysis of Mars "Special Regions": findings of the second MEPAG Special Regions Science Analysis Group (SR-SAG2).

    Science.gov (United States)

    Rummel, John D; Beaty, David W; Jones, Melissa A; Bakermans, Corien; Barlow, Nadine G; Boston, Penelope J; Chevrier, Vincent F; Clark, Benton C; de Vera, Jean-Pierre P; Gough, Raina V; Hallsworth, John E; Head, James W; Hipkin, Victoria J; Kieft, Thomas L; McEwen, Alfred S; Mellon, Michael T; Mikucki, Jill A; Nicholson, Wayne L; Omelon, Christopher R; Peterson, Ronald; Roden, Eric E; Sherwood Lollar, Barbara; Tanaka, Kenneth L; Viola, Donna; Wray, James J

    2014-11-01

    A committee of the Mars Exploration Program Analysis Group (MEPAG) has reviewed and updated the description of Special Regions on Mars as places where terrestrial organisms might replicate (per the COSPAR Planetary Protection Policy). This review and update was conducted by an international team (SR-SAG2) drawn from both the biological science and Mars exploration communities, focused on understanding when and where Special Regions could occur. The study applied recently available data about martian environments and about terrestrial organisms, building on a previous analysis of Mars Special Regions (2006) undertaken by a similar team. Since then, a new body of highly relevant information has been generated from the Mars Reconnaissance Orbiter (launched in 2005) and Phoenix (2007) and data from Mars Express and the twin Mars Exploration Rovers (all 2003). Results have also been gleaned from the Mars Science Laboratory (launched in 2011). In addition to Mars data, there is a considerable body of new data regarding the known environmental limits to life on Earth-including the potential for terrestrial microbial life to survive and replicate under martian environmental conditions. The SR-SAG2 analysis has included an examination of new Mars models relevant to natural environmental variation in water activity and temperature; a review and reconsideration of the current parameters used to define Special Regions; and updated maps and descriptions of the martian environments recommended for treatment as "Uncertain" or "Special" as natural features or those potentially formed by the influence of future landed spacecraft. Significant changes in our knowledge of the capabilities of terrestrial organisms and the existence of possibly habitable martian environments have led to a new appreciation of where Mars Special Regions may be identified and protected. The SR-SAG also considered the impact of Special Regions on potential future human missions to Mars, both as locations of

  6. Online Optimal Switching Frequency Selection for Grid-Connected Voltage Source Inverters

    Directory of Open Access Journals (Sweden)

    Saher Albatran

    2017-12-01

    Full Text Available Enhancing the performance of the voltage source inverters (VSIs without changing the hardware structure has recently acquired an increased amount of interest. In this study, an optimization algorithm, enhancing the quality of the output power and the efficiency of three-phase grid connected VSIs is proposed. Towards that end, the proposed algorithm varies the switching frequency (fsw to maintain the best balance between switching losses of the insulated-gate-bipolar-transistor (IGBT power module as well as the output power quality under all loading conditions, including the ambient temperature effect. Since there is a contradiction with these two measures in relation to the switching frequency, the theory of multi-objective optimization is employed. The proposed algorithm is executed on the platform of Altera® DE2-115 field-programmable-gate-array (FPGA in which the optimal value of the switching frequency is determined online without the need for heavy offline calculations and/or lookup tables. With adopting the proposed algorithm, there is an improvement in the VSI efficiency without degrading the output power quality. Therefore, the proposed algorithm enhances the lifetime of the IGBT power module because of reduced variations in the module’s junction temperature. An experimental prototype is built, and experimental tests are conducted for the verification of the viability of the proposed algorithm.

  7. 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...

  8. A single-phase embedded Z-source DC-AC inverter.

    Science.gov (United States)

    Kim, Se-Jin; Lim, Young-Cheol

    2014-01-01

    In the conventional DC-AC inverter consisting of two DC-DC converters with unipolar output capacitors, the output capacitor voltages of the DC-DC converters must be higher than the DC input voltage. To overcome this weakness, this paper proposes a single-phase DC-AC inverter consisting of two embedded Z-source converters with bipolar output capacitors. The proposed inverter is composed of two embedded Z-source converters with a common DC source and output AC load. Though the output capacitor voltages of the converters are relatively low compared to those of a conventional inverter, an equivalent level of AC output voltages can be obtained. Moreover, by controlling the output capacitor voltages asymmetrically, the AC output voltage of the proposed inverter can be higher than the DC input voltage. To verify the validity of the proposed inverter, experiments were performed with a DC source voltage of 38 V. By controlling the output capacitor voltages of the converters symmetrically or asymmetrically, the proposed inverter can produce sinusoidal AC output voltages. The experiments show that efficiencies of up to 95% and 97% can be achieved with the proposed inverter using symmetric and asymmetric control, respectively.

  9. First high-voltage measurements using Ca{sup +} ions at the ALIVE experiment

    Energy Technology Data Exchange (ETDEWEB)

    König, K., E-mail: kkoenig@ikp.tu-darmstadt.de [Technische Universität Darmstadt, Institut für Kernphysik (Germany); Geppert, Ch. [Universität Mainz, Institut für Kernchemie (Germany); Krämer, J.; Maaß, B. [Technische Universität Darmstadt, Institut für Kernphysik (Germany); Otten, E. W. [Universität Mainz, Institut für Physik (Germany); Ratajczyk, T.; Nörtershäuser, W. [Technische Universität Darmstadt, Institut für Kernphysik (Germany)

    2017-11-15

    Many physics experiments depend on accurate high-voltage measurements to determine for example the exact retardation potential of an electron spectrometer as in the KATRIN experiment or the acceleration voltage of the ions at ISOL facilities. Until now only precision high-voltage dividers can be used to measure voltages up to 65 kV with an accuracy of 1 ppm. However, these dividers need frequent calibration and cross-checking and the direct traceability is not given. In this article we will describe the status of an experiment which aims to measure high voltages using collinear laser spectroscopy and which has the potential to provide a high-voltage standard and hence, a calibration source for precision high-voltage dividers on the 1 ppm level.

  10. The pulse-driven AC Josephson voltage normal; Das pulsgetriebene AC-Josephson-Spannungsnormal

    Energy Technology Data Exchange (ETDEWEB)

    Kieler, Oliver [Physikalisch-Technische Bundesanstalt (PTB), Braunschweig (Germany). Arbeitsgruppe 2.43 ' ' Josephson-Schaltungen' '

    2016-09-15

    In this contribution quantum precise alternating-voltage sources are presented, which make the generation of arbitrary wave forms with highest spectral purity with a high bandwidth from DC up to the MHz range possible. Heartpiece of these Josephson voltage normals is a serial circuit of many thousand Josephson contacts, which make by irradiation with high-frequency radiation (microwaves) the generation of highly precise voltage values possible. Thereby in the current-voltage characteristics stages of constant voltage, so called Shapiro stages, occur. Illustratively these stages can be described by the transfer of a certain number of flux quanta through the Josephson contacts.

  11. Potential need for re-definition of the highest priority recovery action in the Krsko SAG-1

    International Nuclear Information System (INIS)

    Bilic Zabric, T.; Basic, I.

    2005-01-01

    Replacement of old SG (Steam Generators) [7] and the characteristic of new ones throws the question of proper accident management strategy, which leans on philosophy that repair and recovery actions have first priority. In the current NPP Krsko SAMGs (Severe Accident Management Guidelines), water supply to the SG has priority over re-injection water into the core. NPP Krsko reconsidered the highest priority of SAG-1 (inject water to the SG), against the WOG (Westinghouse Owners Group) generic approach (inject water into the core) and potential revision of Severe Accident Phenomenology Evaluations using MAAP (Modular accident Analysis Program) 4.0.5 code. (author)

  12. The LMF triaxial MITL voltage adder system

    International Nuclear Information System (INIS)

    Mazarakis, M.G.; Smith, D.L.; Bennett, L.F.; Lockner, T.R.; Olson, R.E.; Poukey, J.W.

    1992-01-01

    The light-ion microfusion driver design consists of multiple accelerating modules fired in coincidence and sequentially in order to provide the desired ion energy, power pulse shape and energy deposition uniformity on an Inertial Confinement Fusion (ICF) target. The basic energy source is a number of Marx generators which, through the appropriate pulse power conditioning, provide the necessary voltage pulse wave form to the accelerating gaps or feeds of each module. The cavity gaps are inductively isolated, and the voltage addition occurs in the center conductor of the voltage adder which is the positive electrode while the electrons of the sheath flow closer to the outer cylinder which is the magnetically insulated cathode electrode. Each module powers a separate two-stage extraction diode which provides a low divergence ion beam. In order to provide the two separate voltage pulses required by the diode, a triaxial adder system is designed for each module. The voltage addition occurs in two separate MITLs. The center hollow cylinder (anode) of the second MITL also serves as the outer cathode electrode for the extension of the first voltage adder MITL. The voltage of the second stage is about twice that of the first stage. The cavities are connected in series to form the outer cylinder of each module. The accelerating modules are positioned radially in a symmetrical way around the fusion chamber. A preliminary conceptual design of the LMF modules with emphasis on the voltage adders and extension MITLs will be presented and discussed

  13. Voltage fluctuations in granular superconductors in the perpendicular configuration

    International Nuclear Information System (INIS)

    Gerashchenko, O V

    2003-01-01

    The spectral density of voltage fluctuations in granular YBa 2 Cu 3 O 7-δ superconductors in the perpendicular configuration has been studied in the flux flow mode. It has been found that, in this case, the 1/f-voltage noise observed depends weakly on temperature and is associated with motion of a magnetic flux in the superconductor. A comparison of the data obtained with the results of previous measurements in parallel configuration has shown that voltage noise is produced by a single common source, which is presumably associated with self-organization of the critical state in granular superconductors

  14. Simultaneous On-State Voltage and Bond-Wire Resistance Monitoring of Silicon Carbide MOSFETs

    DEFF Research Database (Denmark)

    Baker, Nick; Luo, Haoze; Iannuzzo, Francesco

    2017-01-01

    the voltage between the kelvin-source and power-source can be used to specifically monitor bond-wire degradation. Meanwhile, the drain to kelvin-source voltage can be monitored to track defects in the semiconductor die or gate driver. Through an accelerated aging test on 20 A Silicon Carbide Metal......-Oxide-Semiconductor-Field-Effect Transistors (MOSFETs), it is shown that there are opposing trends in the evolution of the on-state resistances of both the bond-wires and the MOSFET die. In summary, after 50,000 temperature cycles, the resistance of the bond-wires increased by up to 2 mΩ, while the on-state resistance of the MOSFET dies...... decreased by approximately 1 mΩ. The conventional failure precursor (monitoring a single forward voltage) cannot distinguish between semiconductor die or bond-wire degradation. Therefore, the ability to monitor both these parameters due to the presence of an auxiliary-source terminal can provide more...

  15. Bio indication of water quality in the Bogota Sabane using fuzzy logic sagging and aquatic micro invertebrates

    International Nuclear Information System (INIS)

    Gutierrez, Juan David; Riss Wolfgang; Ospina Rodolfo

    2002-01-01

    An application of the Sagging-type fuzzy logic to calculate biological water quality in Bogota, Colombia is presented 28 sites corresponding to 9 watersheds in the Bogota area were used. The organisms selected were: Leptoceridae and Hidrobiosidae as indicators of clean waters, Planariidae and Amphipoda as indicators of polluted waters and Psychodida and Syrphidae as indicators of highly polluted waters Chironomids were also included. In order to prove the degree of reliability of Sugeno-type fuzzy logic, the results obtained were compared with values for the Cfq index, and a highly significant correlation was obtained

  16. Development of a New Cascade Voltage-Doubler for Voltage Multiplication

    OpenAIRE

    Toudeshki, Arash; Mariun, Norman; Hizam, Hashim; Abdul Wahab, Noor Izzri

    2014-01-01

    For more than eight decades, cascade voltage-doubler circuits are used as a method to produce DC output voltage higher than the input voltage. In this paper, the topological developments of cascade voltage-doublers are reviewed. A new circuit configuration for cascade voltage-doubler is presented. This circuit can produce a higher value of the DC output voltage and better output quality compared to the conventional cascade voltage-doubler circuits, with the same number of stages.

  17. A hierarchical model predictive voltage control for NPC/H-bridge converters with a reduced computational burden

    DEFF Research Database (Denmark)

    Gong, Zheng; Dai, Peng; Wu, Xiaojie

    2017-01-01

    In recent years, voltage source multilevel converters are very popular in medium/high-voltage industrial applications, among which the NPC/H-Bridge converter is a popular solution to the medium/high-voltage drive systems. The conventional finite control set model predictive control (FCS-MPC) stra......In recent years, voltage source multilevel converters are very popular in medium/high-voltage industrial applications, among which the NPC/H-Bridge converter is a popular solution to the medium/high-voltage drive systems. The conventional finite control set model predictive control (FCS......-MPC) strategy is not practical for multilevel converters due to their substantial calculation requirements, especially under high number of voltage levels. To solve this problem, a hierarchical model predictive voltage control (HMPVC) strategy with referring to the implementation of g-h coordinate space vector...... and experiments with a down-scaled NPC/H-Bridge converter prototype under various conditions, which validate the proposed HMPVC strategy....

  18. Electrical system architecture having high voltage bus

    Science.gov (United States)

    Hoff, Brian Douglas [East Peoria, IL; Akasam, Sivaprasad [Peoria, IL

    2011-03-22

    An electrical system architecture is disclosed. The architecture has a power source configured to generate a first power, and a first bus configured to receive the first power from the power source. The architecture also has a converter configured to receive the first power from the first bus and convert the first power to a second power, wherein a voltage of the second power is greater than a voltage of the first power, and a second bus configured to receive the second power from the converter. The architecture further has a power storage device configured to receive the second power from the second bus and deliver the second power to the second bus, a propulsion motor configured to receive the second power from the second bus, and an accessory motor configured to receive the second power from the second bus.

  19. Suppressing voltage transients in high voltage power supplies

    International Nuclear Information System (INIS)

    Lickel, K.F.; Stonebank, R.

    1979-01-01

    A high voltage power supply for an X-ray tubes includes voltage adjusting means, a high voltage transformer, switch means connected to make and interrupt the primary current of the transformer, and over-voltage suppression means to suppress the voltage transient produced when the current is switched on. In order to reduce the power losses in the suppression means, an impedance is connected in the transformer primary circuit on operation of the switch means and is subsequently short-circuited by a switch controlled by a timer after a period which is automatically adjusted to the duration of the transient overvoltage. (U.K.)

  20. Grid-Voltage-Feedforward Active Damping for Grid-Connected Inverter with LCL Filter

    DEFF Research Database (Denmark)

    Lu, Minghui; Wang, Xiongfei; Blaabjerg, Frede

    2016-01-01

    For the grid-connected voltage source inverters, the feedforward scheme of grid voltage is commonly adopted to mitigate the current distortion caused by grid background voltages harmonics. This paper investigates the grid-voltage-feedforward active damping for grid connected inverter with LCL...... filter. It reveals that proportional feedforward control can not only fulfill the mitigation of grid disturbance, but also offer damping effects on the LCL filter resonance. Digital delays are intrinsic to digital controlled inverters; with these delays, the feedforward control can be equivalent...

  1. Artifical Excitation of Ferro-Resonance for Testing Electrotechnical Equipment in Distribution Devices with Increased Voltage

    Directory of Open Access Journals (Sweden)

    Ye. V. Dmitriev

    2006-01-01

    Full Text Available On the basis of the developed device for protection against of ferro-resonant and high-frequency cumulative over-voltages an algorithm for obtaining a voltage imitating ferro-resonant over-voltages is proposed in the paper. This algorithm presupposes to apply a voltage to the secondary transformer side from an extraneous source is proposed.

  2. Improvement of power quality using distributed generation

    Energy Technology Data Exchange (ETDEWEB)

    Moreno-Munoz, A.; Lopez-Rodriguez, M.A.; Flores-Arias, J.M.; Bellido-Outerino, F.J. [Universidad de Cordoba, Departamento A.C., Electronica y T.E., Escuela Politecnica Superior, Campus de Rabanales, E-14071 Cordoba (Spain); de-la-Rosa, J.J.G. [Universidad de Cadiz, Area de Electronica, Dpto. ISA, TE y Electronica, Escuela Politecnica Superior Avda, Ramon Puyol, S/N, E-11202-Algeciras-Cadiz (Spain); Ruiz-de-Adana, M. [Universidad de Cordoba, Departamento de Quimica Fisica y Termodinamica Aplicada, Campus de Rabanales, E-14071 Cordoba (Spain)

    2010-12-15

    This paper addresses how Distributed Generation (DG), particularly when configured in Combined Heat and Power (CHP) mode, can become a powerful reliability solution in highlight automated factories, especially when integrated with complimentary Power Quality (PQ) measures. The paper presents results from the PQ audit conducted at a highly automated plant over last year. It was found that the main problems for the equipment installed were voltage sags. Among all categories of electrical disturbances, the voltage sag (dip) and momentary interruption are the nemeses of the automated industrial process. The paper analyzes the capabilities of modern electronic power supplies and the convenience of embedded solution. Finally it is addressed the role of the DG/CHP on the reliability of digital factories. (author)

  3. Secondary Droop for Frequency and Voltage Restoration in Microgrids

    DEFF Research Database (Denmark)

    Nutkani, Inam Ullah; Peng, Wang; Blaabjerg, Frede

    2015-01-01

    Droop based autonomous control offers several advantages such as communication independence, plug-n-play capability and enhanced reliability of the system. Despite these advantages, frequency and voltage of droop controlled microgrid varies with the load change which is one of the major drawback...... of the droop control. Presently, the frequency and voltage restoration in microgrid is achieved through secondary control using low bandwidth communication links. This paper presents secondary-droop based frequency and voltage restoration method which is fully autonomous and independent of communication links....... With the proposed method, the microgrid frequency and voltage can be restored back to nominal value without affecting the power sharing performance of the generation sources. The proposed scheme performance has been validated in simulation for several cases of active and reactive power load conditions....

  4. A grid-voltage-sensorless resistive active power filter with series LC-filter

    DEFF Research Database (Denmark)

    Bai, Haofeng; Wang, Xiongfei; Blaabjerg, Frede

    2017-01-01

    Voltage-sensorless control has been investigated for Voltage Source Inverters (VSIs) for many years due to the reduced system cost and potentially improved system reliability. The VSI based Resistive Active Power Filters (R-APFs) are now widely used to prevent the harmonic resonance in power...... distribution network, for which the voltage sensors are needed in order to obtain the current reference. In this paper a grid-voltage-sensorless control strategy is proposed for the R-APF with series LC-filter. Unlike the traditional resistance emulation method, this proposed control method re...

  5. A Grid-Voltage-Sensorless Resistive Active Power Filter with Series LC-Filter

    DEFF Research Database (Denmark)

    Bai, Haofeng; Wang, Xiongfei; Blaabjerg, Frede

    2018-01-01

    Voltage-sensorless control has been investigated for Voltage Source Inverters (VSIs) for many years due to the reduced system cost and potentially improved system reliability. The VSI based Resistive Active Power Filters (R-APFs) are now widely used to prevent the harmonic resonance in power...... distribution network, for which the voltage sensors are needed in order to obtain the current reference. In this paper a grid-voltage-sensorless control strategy is proposed for the R-APF with series LC-filter. Unlike the traditional resistance emulation method, this proposed control method re...

  6. Transformer inrush current reduction through sequential energization for wind farm applications

    Energy Technology Data Exchange (ETDEWEB)

    Abdulsalam, S.; Xu, W. [Alberta Univ., Edmonton, AB (Canada)

    2008-07-01

    Wind power is considered as one of the fastest growing technologies in the power industry. The electrical configuration of a wind farm consists of long spans of medium voltage collector feeders. Each wind generator is connected to the collector circuit/feeder through either a pad mount oil filled, or a nacelle-mounted dry type transformer. All collector feeders connect to a single collector substation where the connection to the high-voltage transmission is established through a step up transformer. With a large number of wind generators per feeder, large inrush current will flow due to simultaneous transformer energization which can cause high voltage sag at the point of common coupling. Wind farms are generally located in unpopulated remote areas where no access to strong network connection is feasible. It is common to have the PCC on a relatively weak location on the sub-transmission/distribution network. In order to meet interconnection standards requirements, the amount of voltage sag due to the energization of a number of transformers needs to be evaluated. This paper presented an effective solution to the mitigation of inrush currents and associated voltage sag for wind farm applications. The paper presented a diagram of a typical configuration of a wind farm electrical distribution system and also described the analytical methodologies for the evaluation of inrush current level together with simulation results. A simplified analysis and sizing criteria for the associated neutral resistor size was presented. It was concluded that the scheme could significantly reduce inrush current level when a large number of transformers are simultaneously energized. The presented application eliminates the need to sectionalize feeders, thereby simplifying them for the energization process. 6 refs., 5 figs.

  7. Synchronised PWM Schemes for Three-level Inverters with Zero Common-mode Voltage

    DEFF Research Database (Denmark)

    Oleschuk, Valentin; Blaabjerg, Frede

    2002-01-01

    This paper presents results of analysis and comparison of novel synchronised schemes of pulsewidth modulation (PWM), applied to three-level voltage source inverters with control algorithms providing elimination of the common-mode voltage. The proposed approach is based on a new strategy of digital...

  8. Voltage-dependent gating in a "voltage sensor-less" ion channel.

    Directory of Open Access Journals (Sweden)

    Harley T Kurata

    2010-02-01

    Full Text Available The voltage sensitivity of voltage-gated cation channels is primarily attributed to conformational changes of a four transmembrane segment voltage-sensing domain, conserved across many levels of biological complexity. We have identified a remarkable point mutation that confers significant voltage dependence to Kir6.2, a ligand-gated channel that lacks any canonical voltage-sensing domain. Similar to voltage-dependent Kv channels, the Kir6.2[L157E] mutant exhibits time-dependent activation upon membrane depolarization, resulting in an outwardly rectifying current-voltage relationship. This voltage dependence is convergent with the intrinsic ligand-dependent gating mechanisms of Kir6.2, since increasing the membrane PIP2 content saturates Po and eliminates voltage dependence, whereas voltage activation is more dramatic when channel Po is reduced by application of ATP or poly-lysine. These experiments thus demonstrate an inherent voltage dependence of gating in a "ligand-gated" K+ channel, and thereby provide a new view of voltage-dependent gating mechanisms in ion channels. Most interestingly, the voltage- and ligand-dependent gating of Kir6.2[L157E] is highly sensitive to intracellular [K+], indicating an interaction between ion permeation and gating. While these two key features of channel function are classically dealt with separately, the results provide a framework for understanding their interaction, which is likely to be a general, if latent, feature of the superfamily of cation channels.

  9. Best voltage bias-flipping strategy towards maximum piezoelectric power generation

    International Nuclear Information System (INIS)

    Liang, Junrui; Chung, Henry Shu-Hung

    2013-01-01

    In piezoelectric energy harvesting (PEH) systems, energy extracted from piezoelectric structure can be increased by making piezoelectric voltage in phase with vibration velocity and raising the voltage amplitude. Such voltage manipulations can be realized by synchronously flipping the piezoelectric voltage with respect to a bias dc source at every displacement extremum. Given that net harvested energy is obtained by deducting dissipated energy from total extracted energy, a sophisticated voltage bias-flipping scheme, which can maximize extracted energy at low dissipative cost, is required towards harvested energy optimization. This paper extends the state of the art by proposing the best bias-flip strategy, which is delivered on conceptual synchronized multiple bias-flip (SMBF) interface circuits. The proposed strategy coordinates both requirements on larger voltage change in synchronized instant for more extracted energy and smaller voltage change in each bias-flip action for less dissipated energy. It not only leads to further enhancement of harvesting capability beyond existing solutions, but also provides an unprecedented physical insight on maximum achievable harvesting capability of PEH interface circuit

  10. Discussion - a high voltage DC generator

    International Nuclear Information System (INIS)

    Bhagwat, P.V.; Singh, Jagir; Hattangadi, V.A.

    1993-01-01

    One of the requirements for a high power ion source is a high voltage, high current DC generator. The high voltage, high current generator, DISCATRON, presently under development in our laboratory is a rotating disc type electrostatic generator similar in design to the one reported by A. Isoya et al. (1985). It is compact and rugged electrostatic DC generator based on the principle of induction charging by pellet chains used in the pelletron accelerator. It is, basically, a constant-current device with little stored energy, so that, in case of a breakdown, damage to the equipment connected to the output terminals is minimal. Since the present generator is only a proto-type, meant for a study of the practical difficulties that would be encountered in its manufacture, the output voltage and current specified has been kept quite modest viz., 300 kV at 500 μA, maximum. Some results of the preliminary tests carried out with this generator are described. (author). 4 figs

  11. High-voltage, high-power architecture considerations

    International Nuclear Information System (INIS)

    Moser, R.L.

    1985-01-01

    Three basic EPS architectures, direct energy transfer, peak-power tracking, and a potential EPS architecture for a nuclear reactor are described and compared. Considerations for the power source and energy storage are discussed. Factors to be considered in selecting the operating voltage are pointed out. Other EPS architecture considerations are autonomy, solar array degrees of freedom, and EPS modularity. It was concluded that selection of the power source and energy storage has major impacts on the spacecraft architecture and mass

  12. Autonomous Operation of Low Voltage Microgrids

    Directory of Open Access Journals (Sweden)

    Irena Wasiak

    2014-12-01

    Full Text Available The article describes the possibilities of LV microgrids operation in the island mode. Control strategies of energy sources connected to the grid by means of invertors are discussed, either for a microgrid connected to the supplying network or during the island mode operation. The presented results of research were conducted at the Laboratory of Distributed Generation at Lodz University of Technology. The study was performed for two variants of reference voltage source: the battery storage and microturbine respectively.

  13. Transient voltage sharing in series-coupled high voltage switches

    Directory of Open Access Journals (Sweden)

    Editorial Office

    1992-07-01

    Full Text Available For switching voltages in excess of the maximum blocking voltage of a switching element (for example, thyristor, MOSFET or bipolar transistor such elements are often coupled in series - and additional circuitry has to be provided to ensure equal voltage sharing. Between each such series element and system ground there is a certain parasitic capacitance that may draw a significant current during high-speed voltage transients. The "open" switch is modelled as a ladder network. Analy­sis reveals an exponential progression in the distribution of the applied voltage across the elements. Overstressing thus oc­curs in some of the elements at levels of the total voltage that are significantly below the design value. This difficulty is overcome by grading the voltage sharing circuitry, coupled in parallel with each element, in a prescribed manner, as set out here.

  14. Lowering effect of radioactive irradiation on breakdown voltage and electron avalanche pulse characteristics

    International Nuclear Information System (INIS)

    Kawahashi, Akira; Nakano, Toru; Hosokawa, Tatsuzo; Miyoshi, Yosinori.

    1976-01-01

    In the time resolving measurement of the growing process and breakdown of electron avalanche in a gap of uniform electric field, the phenomenon that DC breakdown voltage slightly lowered was observed when β ray was irradiated as the initial electron source, as compared with unirradiated condition. Beta source used is 90 Sr- 90 Y of 2 mCi in radiative equilibrium. The experimental results and the examination are described in detail. In brief, the remarkable superposition of succeeding avalanche pulse over the preceeding avalanche pulse waveform was observed under the gap condition in which the breakdown voltage decreased in β-ray irradiation. Thus this superposition of avalanche pulses is considered as one of the causes of the breakdown voltage reduction. When β source is used as the initial electron source, the number of supplied initial electrons is very large as compared with unity, and at the same time, a great number of initial electrons can be supplied within the diffusion radius r of avalanche. Then the effect of initial electron number n 0 was considered by employing a diagram for breakdown scheme. The transition from Townsend type breakdown to streamer type breakdown occurs owing to increasing n 0 , and in that condition, the breakdown voltage lowers slightly. (Wakatsuki, Y)

  15. Analysis and Design of Symmetrical Capacitor Diode Voltage Multiplier Driven by LCL-T Resonant Converter

    Science.gov (United States)

    Malviya, Devesh; Borage, Mangesh Balkrishna; Tiwari, Sunil

    2017-12-01

    This paper investigates the possibility of application of Resonant Immittance Converters (RICs) as a current source for the current-fed symmetrical Capacitor-Diode Voltage Multiplier (CDVM) with LCL-T Resonant Converter (RC) as an example. Firstly, detailed characterization of the current-fed symmetrical CDVM is carried out using repeated simulations followed by the normalization of the simulation results in order to derive the closed-form curve fit equations to predict the operating modes, output voltage and ripple in terms of operating parameters. RICs, due to their ability to convert voltage source into a current source, become a possible candidate for the realization of current source for the current-fed symmetrical CDVM. Detailed analysis, optimization and design of LCL-T RC with CDVM is performed in this paper. A step by step design procedure for the design of CDVM and the converter is proposed. A 5-stage prototype symmetrical CDVM driven by LCL-T RC to produce 2.5 kV, 50 mA dc output voltage is designed, built and tested to validate the findings of the analysis and simulation.

  16. Voltage and Current Regulators Design of Power Converters in Islanded Microgrids based on State Feedback Decoupling

    DEFF Research Database (Denmark)

    Federico, de Bosio; de Sousa Ribeiro, Luiz Antonio; Freijedo Fernandez, Francisco Daniel

    2016-01-01

    In stand-alone microgrids based on voltage source inverters state feedback coupling between the capacitor voltage and inductor current degrades significantly the dynamics performance of voltage and current regulators. The decoupling of the controlled states is proposed, considering the limitations...

  17. Thermal Performance and Efficiency Investigation of Conventional Boost, Z-source and Y-source Converters

    DEFF Research Database (Denmark)

    Gadalla, Brwene Salah Abdelkarim; Schaltz, Erik; Siwakoti, Yam Prasad

    2016-01-01

    Boost converters are needed in many applications that require the output voltage to be higher than the input voltage. Recently, boost type converters have been attracted by the industrial applications, and hence it has become an extremely hot topic of research. Recently, many researchers proposed...... the impedance source converters with their unique advantages as having a high voltage gain in a small range of duty cycle ratio. However, the thermal behaviour of the semiconductor devices and passive elements in the impedance source converter is an important issue from a reliability point of view and has...... not been investigated yet. Therefore this paper presents a comparison between the conventional boost, the Z-source, and the Y-source converters based on the thermal evaluation of semiconductors. In addition, the three topologies are also compared with respect to their efficiency. The operational principle...

  18. A Transformerless Medium Voltage Multiphase Motor Drive System

    Directory of Open Access Journals (Sweden)

    Dan Wang

    2016-04-01

    Full Text Available A multiphase motor has several major advantages, such as high reliability, fault tolerance, and high power density. It is a critical issue to develop a reliable and efficient multiphase motor drive system. In this paper, a transformerless voltage source converter-based drive system for a medium-voltage (MV multiphase motor is proposed. This drive converter employs cascaded H-bridge rectifiers loaded by H-bridge inverters as the interface between the grid and multiphase motor. The cascaded H-bridge rectifier technique makes the drive system able to be directly connected to the MV grid without the phase-shifting transformer because it can offset the voltage level gap between the MV grid and the semiconductor devices, provide near-sinusoidal AC terminal voltages without filters, and draw sinusoidal line current from the grid. Based on a digital signal processor (DSP, a complete improved Phase Disposition Pulse Width Modulation (PD-PWM method is developed to ensure the individual DC-link capacitor voltage balancing for enhancing the controllability and limiting the voltage and power stress on the H-bridge cells. A downscaled prototype is designed and developed based on a nine-phase motor. The experimental results verify the excellent performances of the proposed drive system and control strategy in steady-state and variant-frequency startup operations.

  19. Model predictive control for Z-source power converter

    DEFF Research Database (Denmark)

    Mo, W.; Loh, P.C.; Blaabjerg, Frede

    2011-01-01

    This paper presents Model Predictive Control (MPC) of impedance-source (commonly known as Z-source) power converter. Output voltage control and current control for Z-source inverter are analyzed and simulated. With MPC's ability of multi- system variables regulation, load current and voltage...

  20. Mesozoic to Cenozoic tectonic transition process in Zhanhua Sag, Bohai Bay Basin, East China

    Science.gov (United States)

    Cheng, Yanjun; Wu, Zhiping; Lu, Shunan; Li, Xu; Lin, Chengyan; Huang, Zheng; Su, Wen; Jiang, Chao; Wang, Shouye

    2018-04-01

    The Zhanhua sag is part of the Bohai Bay intracontinental basin system that has developed since the Mesozoic in East China. The timing of this basin system coincides with the final assembly of East Asia and the development of Western Pacific-type plate margin. Here we use 3-D seismic and core log data to investigate the evolution of this basin and discuss its broad tectonic settings. Our new structural study of Zhanhua sag suggests that there are four major tectonic transitions occurred in the Bohai Bay Basin during Mesozoic and Cenozoic: (1) The first tectonic transition was from stable Craton to thrusting during the Triassic, mainly caused by the South China Block's subduction northward beneath the North China Block, which induced the formation of the NW-striking thrust faults. (2) The second tectonic transition was mainly characterized by a change from compression to extension, which can be further divided into two-stages. At the first stage, two episodes of NW-SE shortening occurred in East Asia during Early-Middle Jurassic and Late Jurassic-earliest Cretaceous, respectively. At the second stage, the extension and left-lateral shearing took place during Early Cretaceous while compression occurred during Late Cretaceous. The NW-striking thrust faults changed to normal faults and the NNE-striking left-lateral strike-slip faults started to influence the eastern part of the basin. (3) The third transition occurred when the NW-SE extension and NNE-striking right-lateral shearing started to form during Paleogene, and the peak deformation happen around 40 Ma due to the change of the subduction direction of Pacific Plate relative to Eurasia Plate. The NE-striking normal faults are the main structure, and the pre-existing NNE-striking strike-slip faults changed from left-lateral to right-lateral. (4) The fourth transition saw the regional subsidence during Neogene, which was probably caused by the India-Asia "Hard collision" between 25 and 20 Ma.

  1. New strategy for eliminating zero-sequence circulating current between parallel operating three-level NPC voltage source inverters

    DEFF Research Database (Denmark)

    Li, Kai; Dong, Zhenhua; Wang, Xiaodong

    2018-01-01

    buses, that are operating in parallel. First, an equivalent model of ZSCC in a three-phase three-level NPC inverter paralleled system is developed. Second, on the basis of the analysis of the excitation source of ZSCCs, i.e., the difference in common mode voltages (CMVs) between paralleled inverters......, the ZCMV-PWM method is presented to reduce CMVs, and a simple electric circuit is adopted to control ZSCCs and neutral point potential. Finally, simulation and experiment are conducted to illustrate effectiveness of the proposed strategy. Results show that ZSCCs between paralleled inverters can...... be eliminated effectively under steady and dynamic states. Moreover, the proposed strategy exhibits the advantage of not requiring carrier synchronization. It can be utilized in inverters with different types of filter....

  2. High voltage calibration of the TANSY-KM5 neutron detectors

    International Nuclear Information System (INIS)

    Grosshoeg, G.; Belle, P. van; Wilson, D.

    1996-11-01

    We have developed a procedure for the high voltage calibration of the TANSY neutron detectors. The procedure is based on the work done during the construction of the spectrometer. A program is written for the measurement of the sensitivity of the neutron detectors as a function of the high voltage. The data are transferred to a PC for evaluation. We use a Cobalt source for the calibration. With the PC the voltage corresponding to the effective Compton edge is found. The voltage settings for the neutron detectors are calculated and stored in a file suitable for input to a program that is used to control the instrument. A measurement is reported that shows that the reproducibility of the measurement is good. 4 refs

  3. Voltage-Level Selection of Future Two-Level LVdc Distribution Grids

    DEFF Research Database (Denmark)

    Diaz, Enrique Rodriguez; Chen, Fang; Quintero, Juan Carlos Vasquez

    2016-01-01

    significantly. Microgrids (MGs) come as a suitable solution for the installation of distributed sources in the low voltage grid, where most of the consumers are sparsely located. Microgrids ease the integration of distributed generators (DGs), especially renewable energy sources like solar panels and small wind...

  4. Voltage regulating circuit

    NARCIS (Netherlands)

    2005-01-01

    A voltage regulating circuit comprising a rectifier (2) for receiving an AC voltage (Vmains) and for generating a rectified AC voltage (vrec), and a capacitor (3) connected in parallel with said rectified AC voltage for providing a DC voltage (VDC) over a load (5), characterized by a unidirectional

  5. Usefulness of Toxoplasma gondii recombinant antigens (GRA1, GRA7 and SAG1) in an immunoglobulin G avidity test for the serodiagnosis of toxoplasmosis

    DEFF Research Database (Denmark)

    Pietkiewicz, H; Hiszczyńska-Sawicka, E; Kur, J

    2007-01-01

    The precise diagnosis of an acute and recent Toxoplasma infection in pregnant women and the newborn child is important before treatment. This study describes a new Toxoplasma gondii IgG avidity test based on a combination of recombinant GRA1, GRA7 and SAG1 antigens and shows that this test is use...

  6. Design philosophy and use of high voltage power systems for multi-megawatt ion beam accelerators

    International Nuclear Information System (INIS)

    Barber, G.C.; Broverman, A.Y.; Hill, R.E.; Loring, C.M.; Ponte, N.S.

    1977-01-01

    The requirements for a neutral beam high voltage power system are derived from the characteristics of the ion source. High voltage system component characteristic requirements and choices are described

  7. Coordinated voltage control in offshore HVDC connected cluster of wind power plants

    DEFF Research Database (Denmark)

    Sakamuri, Jayachandra Naidu; Rather, Zakir Hussain; Rimez, Johan

    This paper presents a coordinated voltage control scheme (CVCS) for a cluster of offshore wind power plants connected to a voltage-source converter-based high-voltage direct current system. The primary control point of the proposed voltage control scheme is the introduced Pilot bus, which is having...... by dispatching reactive power references to each wind turbine (WT) in the wind power plant cluster based on their available reactive power margin and network sensitivity-based participation factors, which are derived from the dV/dQ sensitivity of a WT bus w.r.t. the Pilot bus. This method leads...

  8. Development of Phase Lock Loop System for Synchronisation of a Hybrid System with the Grid

    Directory of Open Access Journals (Sweden)

    A. S. Abubakar

    2016-06-01

    Full Text Available Phase locked loop (PLL is an important part of the control unit of the grid connected power converter. The method of zero crossing detection (ZCD does not produce accurate phase information when grid is non-ideal. In this work, a synchronous reference frame (SRF PLL method to obtain accurate phase information when the grid voltages are unbalanced is proposed. The performances of the PLL have been verified for ideal and abnormal grid conditions such as unbalance, voltage sag, faults condition etc. Based on the results obtained, the developed PLL gives better fault ride when unbalances in the three phase input signals are overall handled well by the PLL system as it locks the two signal back within the first cycle. It also overcomes a phase jump after 5 milli-seconds from the time the fault was introduced and performs better tracking of the grid voltage and that of the renewable energy source.

  9. Development of Phase Lock Loop System for Synchronisation of a Hybrid System with the Grid

    Directory of Open Access Journals (Sweden)

    A. S. Abubakar

    2016-12-01

    Full Text Available Phase locked loop (PLL is an important part of the control unit of the grid connected power converter. The method of zero crossing detection (ZCD does not produce accurate phase information when grid is non-ideal. In this work, a synchronous reference frame (SRF PLL method to obtain accurate phase information when the grid voltages are unbalanced is proposed. The performances of the PLL have been verified for ideal and abnormal grid conditions such as unbalance, voltage sag, faults condition etc. Based on the results obtained, the developed PLL gives better fault ride when unbalances in the three phase input signals are overall handled well by the PLL system as it locks the two signal back within the first cycle. It also overcomes a phase jump after 5 milli-seconds from the time the fault was introduced and performs better tracking of the grid voltage and that of the renewable energy source.

  10. A low-frequency high-voltage rf-barrier-bunching system for high-intensity neutron source compressor rings

    International Nuclear Information System (INIS)

    Hardek, T.W.; Ziomek, C.; Rees, D.

    1995-01-01

    A Los Alamos design for a 1-MW pulsed neutron source incorporates a ring utilizing an rf-barrier bunching system. This bunching concept allows uniform longitudinal beam distributions with low momentum spread. Bunching cavities are operated at the revolution frequency (1.5 MHz in this case) and each of the 2nd, 3rd, 4th, and 5th revolution frequency harmonics. Their effects combine to maintain a beam free gap in the longitudinal distribution of the accumulated beam. The cavities are driven by low-plate-resistance common-cathode configured retrode amplifiers incorporating local rf feedback. Additional adaptive feed-forward hardware is included to reduce the beam-induced bunching-gap voltages well below that achievable solely with rf feedback. Details of this system are presented along with a discussion of the various feed-back and feed-forward techniques incorporated

  11. 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)

  12. Neutron generator tube ion source control

    International Nuclear Information System (INIS)

    Bridges, J.R.

    1982-01-01

    A system is claimed for controlling the output of a neutron generator tube of the deuterium-tritium accelerator type and having an ion source to produce sharply defined pulses of neutrons for well logging use. It comprises: means for inputting a relatively low voltage input control pulse having a leading edge and a trailing edge; means, responsive to the input control pulse, for producing a relatively high voltage ion source voltage pulse after receipt of the input pulse; and means, responsive to the input control pulse, for quenching, after receipt of the input pulse, the ion source control pulse, thereby providing a sharply time defined neutron output from the generator tube

  13. Low-cost wireless voltage & current grid monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Hines, Jacqueline [SenSanna Inc., Arnold, MD (United States)

    2016-12-31

    This report describes the development and demonstration of a novel low-cost wireless power distribution line monitoring system. This system measures voltage, current, and relative phase on power lines of up to 35 kV-class. The line units operate without any batteries, and without harvesting energy from the power line. Thus, data on grid condition is provided even in outage conditions, when line current is zero. This enhances worker safety by detecting the presence of voltage and current that may appear from stray sources on nominally isolated lines. Availability of low-cost power line monitoring systems will enable widespread monitoring of the distribution grid. Real-time data on local grid operating conditions will enable grid operators to optimize grid operation, implement grid automation, and understand the impact of solar and other distributed sources on grid stability. The latter will enable utilities to implement eneygy storage and control systems to enable greater penetration of solar into the grid.

  14. Evaluation of a real-time PCR assay based on the single-copy SAG1 gene for the detection of Toxoplasma gondii.

    Science.gov (United States)

    Yu, Haijie; Huang, Bin; Zhuo, Xunhui; Chen, Xueqiu; Du, Aifang

    2013-11-08

    Real-time PCR-based detection of Toxoplasma gondii is very sensitive and convenient for diagnosing toxoplasmosis. However, the performance of the PCR assays could be influenced by the target gene chosen. Here we evaluate a real-time PCR assay using double-stranded DNA dyes (SYBR(®) Green I assay) with a new set of primers targeting the SAG1 gene for the fast and specific detection of T. gondii. The assay showed higher sensitivity than conventional PCR protocols using T. gondii DNA as template. The detection limit of the developed real-time PCR assay was in the order of 1 tachyzoite. The assay was also assessed by experimentally infected mice and showed positive results for blood (25%), spleen (50%) and lung (50%) as early as 1 dpi. The specificity of the assay was confirmed by using DNA from Neospora caninum, Escherichia coli, Babesia bovis, Trypanosoma brucei, Cryptosporidium parvum, and Toxocara canis. Assay applicability was successfully tested in blood samples collected from slaughtered pigs. These results indicate that, based on SYBR(®) green I, the quantitative SAG1 assay may also be useful in the study of the pathogenicity, immunoprophylaxis, and treatment of T. gondii. Copyright © 2013 Elsevier B.V. All rights reserved.

  15. Device and methods for writing and erasing analog information in small memory units via voltage pulses

    Science.gov (United States)

    El Gabaly Marquez, Farid; Talin, Albert Alec

    2018-04-17

    Devices and methods for non-volatile analog data storage are described herein. In an exemplary embodiment, an analog memory device comprises a potential-carrier source layer, a barrier layer deposited on the source layer, and at least two storage layers deposited on the barrier layer. The memory device can be prepared to write and read data via application of a biasing voltage between the source layer and the storage layers, wherein the biasing voltage causes potential-carriers to migrate into the storage layers. After initialization, data can be written to the memory device by application of a voltage pulse between two storage layers that causes potential-carriers to migrate from one storage layer to another. A difference in concentration of potential carriers caused by migration of potential-carriers between the storage layers results in a voltage that can be measured in order to read the written data.

  16. New multilevel inverter with reduction of switches and gate driver

    Energy Technology Data Exchange (ETDEWEB)

    Banaei, M.R., E-mail: m.banaei@azaruniv.ed [Electrical Engineering Department, Faculty of Engineering, Azarbaijan University of Tarbiat Moallem, Tabriz (Iran, Islamic Republic of); Salary, E. [Electrical Engineering Department, Faculty of Engineering, Azarbaijan University of Tarbiat Moallem, Tabriz (Iran, Islamic Republic of)

    2011-02-15

    This paper presents a novel topology for symmetrical cascade multilevel converter. The proposed circuit consists of series connected sub multilevel converters units and it can generate DC voltage levels similar to other topologies. The proposed topology results in reduction of switches number, losses, installation area and converter cost. This converter has been used in a Dynamic Voltage Restorer (DVR). Simulation results carried out by MATLAB/SIMULINK show the voltage injection capability of converter and the efficiency of its controller in compensating voltage sag and swell.

  17. Source of seismic signals

    Energy Technology Data Exchange (ETDEWEB)

    Frankovskii, B.A.; Khor' yakov, K.A.

    1980-08-30

    Patented is a source of seismic signals consisting of a shock generator with a basic low-voltage and auxillary high-voltage stator coils, a capacitive transformer and control switches. To increase the amplitude of signal excitation a condensor battery and auxillary commutator are introduced into the device, which are connected in parallel and serially into the circuit of the main low-voltage stator coil.

  18. Beyond voltage-gated ion channels: Voltage-operated membrane proteins and cellular processes.

    Science.gov (United States)

    Zhang, Jianping; Chen, Xingjuan; Xue, Yucong; Gamper, Nikita; Zhang, Xuan

    2018-04-18

    Voltage-gated ion channels were believed to be the only voltage-sensitive proteins in excitable (and some non-excitable) cells for a long time. Emerging evidence indicates that the voltage-operated model is shared by some other transmembrane proteins expressed in both excitable and non-excitable cells. In this review, we summarize current knowledge about voltage-operated proteins, which are not classic voltage-gated ion channels as well as the voltage-dependent processes in cells for which single voltage-sensitive proteins have yet to be identified. Particularly, we will focus on the following. (1) Voltage-sensitive phosphoinositide phosphatases (VSP) with four transmembrane segments homologous to the voltage sensor domain (VSD) of voltage-gated ion channels; VSPs are the first family of proteins, other than the voltage-gated ion channels, for which there is sufficient evidence for the existence of the VSD domain; (2) Voltage-gated proton channels comprising of a single voltage-sensing domain and lacking an identified pore domain; (3) G protein coupled receptors (GPCRs) that mediate the depolarization-evoked potentiation of Ca 2+ mobilization; (4) Plasma membrane (PM) depolarization-induced but Ca 2+ -independent exocytosis in neurons. (5) Voltage-dependent metabolism of phosphatidylinositol 4,5-bisphosphate (PtdIns[4,5]P 2 , PIP 2 ) in the PM. These recent discoveries expand our understanding of voltage-operated processes within cellular membranes. © 2018 Wiley Periodicals, Inc.

  19. Application of Multipoint DC Voltage Control in VSC-MTDC System

    Directory of Open Access Journals (Sweden)

    Yang Xi

    2013-01-01

    Full Text Available The voltage-source-converter- (VSC- based multiterminal VSC-HVDC power transmission system (VSC-MTDC is an ideal approach to connect wind farm with power grid. Analyzing the characteristics of doubly fed induction generators as well as the basic principle and the control strategy of VSC-MTDC, a multiterminal DC voltage control strategy suitable for wind farm connected with VSC-MTDC is proposed. By use of PSCAD/EMTDC, the proposed control strategy is simulated, and simulation results show that using the proposed control strategy the conversion between constant power control mode and constant DC voltage control mode can be automatically implemented; thus the DC voltage stability control and reliable power output of wind farm can be ensured after the fault-caused outage of converter station controlled by constant DC voltage and under other faults. The simulation result shows that the model can fulfill multiterminal power transmission and fast response control.

  20. Development of a fast voltage control method for electrostatic accelerators

    International Nuclear Information System (INIS)

    Lobanov, Nikolai R.; Linardakis, Peter; Tsifakis, Dimitrios

    2014-01-01

    The concept of a novel fast voltage control loop for tandem electrostatic accelerators is described. This control loop utilises high-frequency components of the ion beam current intercepted by the image slits to generate a correction voltage that is applied to the first few gaps of the low- and high-energy acceleration tubes adjoining the high voltage terminal. New techniques for the direct measurement of the transfer function of an ultra-high impedance structure, such as an electrostatic accelerator, have been developed. For the first time, the transfer function for the fast feedback loop has been measured directly. Slow voltage variations are stabilised with common corona control loop and the relationship between transfer functions for the slow and new fast control loops required for optimum operation is discussed. The main source of terminal voltage instabilities, which are due to variation of the charging current caused by mechanical oscillations of charging chains, has been analysed

  1. High voltage high brightness electron accelerators with MITL voltage adder coupled to foilless diodes

    International Nuclear Information System (INIS)

    Mazarakis, M.G.; Poukey, J.W.; Frost, C.A.; Shope, S.L.; Halbleib, J.A.; Turman, B.N.

    1993-01-01

    During the last ten years the authors have extensively studied the physics and operation of magnetically-immersed electron foilless diodes. Most of these sources were utilized as injectors to high current, high energy linear induction accelerators such as those of the RADLAC family. Recently they have experimentally and theoretically demonstrated that foilless diodes can be successfully coupled to self-magnetically insulated transmission line voltage adders to produce very small high brightness, high definition (no halo) electron beams. The RADLAC/SMILE experience opened the path to a new approach in high brightness, high energy induction accelerators. There is no beam drifting through the device. The voltage addition occurs in a center conductor, and the beam is created at the high voltage end in an applied magnetic field diode. This work was motivated by the remarkable success of the HERMES-III accelerator and the need to produce small radius, high energy, high current electron beams for air propagation studies and flash x-ray radiography. In this paper they present experimental results compared with analytical and numerical simulations in addition to design examples of devices that can produce multikiloamp electron beams of as high as 100 MV energies and radii as small as 1 mm

  2. Extended topologies of tapped-inductor Z-source inverters

    DEFF Research Database (Denmark)

    Zhu, Miao; Li, Ding; Gao, Feng

    2011-01-01

    In this paper, two distinct types of tapped-inductor Z-source impedance networks are proposed for implementing high performance voltage-type inverters topologies with strong voltage boost inversion abilities and less components' stresses. All proposed topologies can in principle be unified...... into a generic network entity, which is termed hybrid-source tapped-inductor impedance network. The resulting novel Z-source inverters would have a higher output voltage gain and other unique advantages that currently have not yet been investigated. Theoretical analysis for explaining these operating features...

  3. Optimum voltage of auxiliary systems for thermal and nuclear power plants

    International Nuclear Information System (INIS)

    Tokumitsu, Iwao; Segawa, Motomichi

    1979-01-01

    In the power plants in Japan, their unit power output has been greatly enhanced since the introduction of new powerful thermal power plants from 1950's to 1960's. In both thermal and nuclear power plants, 1,000 MW machines have been already in operation. The increase of unit power output results in the increase of in-plant load capacity. Of these the voltage adopted for in-plant low voltage systems is now mainly 440 V at load terminals, and the voltage for in-plant high voltage systems has been changing to 6 kV level via 3 kV and 4 kV levels. As plant capacity increases, the load of low voltage systems significantly increases, and it is required to raise the voltage of 400 V level. By the way, the low voltage in AC is specified to be not higher than 600 V. This makes the change within the above range comparatively easy. Considering these conditions, it is recommended to change the voltage for low voltage systems to 575 V at power source terminals and 550 V at load terminals. Some merits in constructing power systems and in economy by raising the voltage were examined. Though demerits are also found, they are only about 15% of total merits. The most advantageous point in raising the voltage is to be capable of increasing the supplying range to low voltage system loads. (Wakatsuki, Y.)

  4. Voltage management of distribution networks with high penetration of distributed photovoltaic generation sources

    Science.gov (United States)

    Alyami, Saeed

    Installation of photovoltaic (PV) units could lead to great challenges to the existing electrical systems. Issues such as voltage rise, protection coordination, islanding detection, harmonics, increased or changed short-circuit levels, etc., need to be carefully addressed before we can see a wide adoption of this environmentally friendly technology. Voltage rise or overvoltage issues are of particular importance to be addressed for deploying more PV systems to distribution networks. This dissertation proposes a comprehensive solution to deal with the voltage violations in distribution networks, from controlling PV power outputs and electricity consumption of smart appliances in real time to optimal placement of PVs at the planning stage. The dissertation is composed of three parts: the literature review, the work that has already been done and the future research tasks. An overview on renewable energy generation and its challenges are given in Chapter 1. The overall literature survey, motivation and the scope of study are also outlined in the chapter. Detailed literature reviews are given in the rest of chapters. The overvoltage and undervoltage phenomena in typical distribution networks with integration of PVs are further explained in Chapter 2. Possible approaches for voltage quality control are also discussed in this chapter, followed by the discussion on the importance of the load management for PHEVs and appliances and its benefits to electric utilities and end users. A new real power capping method is presented in Chapter 3 to prevent overvoltage by adaptively setting the power caps for PV inverters in real time. The proposed method can maintain voltage profiles below a pre-set upper limit while maximizing the PV generation and fairly distributing the real power curtailments among all the PV systems in the network. As a result, each of the PV systems in the network has equal opportunity to generate electricity and shares the responsibility of voltage

  5. Source of sustained voltage difference between the xylem of a potted Ficus benjamina tree and its soil.

    Directory of Open Access Journals (Sweden)

    Christopher J Love

    Full Text Available It has long been known that there is a sustained electrical potential (voltage difference between the xylem of many plants and their surrounding soil, but the mechanism behind this voltage has remained controversial. After eliminating any extraneous capacitive or inductive couplings and ground-mediated electric current flows, we have measured sustained differences of 50-200 mV between the xylem region of a Faraday-caged, intact, potted Ficus benjamina tree and its soil, as well as between its cut branches and soils and ionic solutions standardized to various pH values. Using identical platinum electrodes, no correlation between the voltage and time of day, illumination, sap flow, electrode elevation, or ionic composition of soil was found, suggesting no direct connection to simple dissimilar-metal redox reactions or transpirational activity. Instead, a clear relationship between the voltage polarity and magnitude and the pH difference between xylem and soil was observed. We attribute these sustained voltages to a biological concentration cell likely set up by the homeostatic mechanisms of the tree. Potential applications of this finding are briefly explored.

  6. Enhanced Voltage Control of VSC-HVDC Connected Offshore Wind Farms Based on Model Predictive Control

    DEFF Research Database (Denmark)

    Guo, Yifei; Gao, Houlei; Wu, Qiuwei

    2018-01-01

    This paper proposes an enhanced voltage control strategy (EVCS) based on model predictive control (MPC) for voltage source converter based high voltage direct current (VSCHVDC) connected offshore wind farms (OWFs). In the proposed MPC based EVCS, all wind turbine generators (WTGs) as well...... as the wind farm side VSC are optimally coordinated to keep voltages within the feasible range and reduce system power losses. Considering the high ratio of the OWF collector system, the effects of active power outputs of WTGs on voltage control are also taken into consideration. The predictive model of VSC...

  7. High-current and low acceleration voltage arsenic ion implanted polysilicon-gate and source-drain electrode Si mos transistor

    International Nuclear Information System (INIS)

    Saito, Yasuyuki; Sugimura, Yoshiro; Sugihara, Michiyuki

    1993-01-01

    The fabrication process of high current arsenic (As) ion implanted polysilicon (Si) gate and source drain (SD) electrode Si n-channel metal oxide-semiconductor field effect transistor (MOSFET) was examined. Poly Si film n-type doping was performed by using high current (typical current: 2mA) and relatively low acceleration voltage (40keV) As ion implantation technique (Lintott series 3). It was observed that high dose As implanted poly Si films as is show refractoriness against radical fluorine excited by microwave. Using GCA MANN4800 (m/c ID No.2, resist: OFPR) mask pattern printing technique, the high current As ion implantation technique and radical fluorine gas phase etching (Chemical dry etching: CDE) technique, the n-channel Poly Si gate (ρs = ≅100Ω/□) enhancement MQSFETs(ρs source drain = ≅50Ω/□, SiO 2 gate=380 angstrom) with off-leak-less were obtained on 3 inch Czochralski grown 2Ωcm boron doped p type wafers (Osaka titanium). By the same process, a 8 bit single chip μ-processor with 26MHz full operation was performed

  8. A high open-circuit voltage gallium nitride betavoltaic microbattery

    International Nuclear Information System (INIS)

    Cheng, Zaijun; Chen, Xuyuan; San, Haisheng; Feng, Zhihong; Liu, Bo

    2012-01-01

    A high open-circuit voltage betavoltaic microbattery based on a gallium nitride (GaN) p–i–n homojunction is demonstrated. As a beta-absorbing layer, the low electron concentration of the n-type GaN layer is achieved by the process of Fe compensation doping. Under the irradiation of a planar solid 63 Ni source with activity of 0.5 mCi, the open-circuit voltage of the fabricated microbattery with 2 × 2 mm 2 area reaches as much as 1.64 V, which is the record value reported for betavoltaic batteries with 63 Ni source, the short-circuit current was measured as 568 pA and the conversion effective of 0.98% was obtained. The experimental results suggest that GaN is a high-potential candidate for developing the betavoltaic microbattery. (paper)

  9. Realization of Nth-Order Voltage Transfer Function using Current Conveyors CCII

    Directory of Open Access Journals (Sweden)

    K. Vrba

    1997-06-01

    Full Text Available A universal method for the realization of arbitrary voltage transfer function in canonic form is presented. A voltage-controlled current-source using a plus-type second-generation current conveyor is here applied as the basic building element. Filters designed according to this method have a high input impedance and low sensitivity to variations of circuit parameters. All passive elements are grounded.

  10. E-beam high voltage switching power supply

    Science.gov (United States)

    Shimer, Daniel W.; Lange, Arnold C.

    1997-01-01

    A high power, solid state power supply is described for producing a controllable, constant high voltage output under varying and arcing loads suitable for powering an electron beam gun or other ion source. The present power supply is most useful for outputs in a range of about 100-400 kW or more. The power supply is comprised of a plurality of discrete switching type dc-dc converter modules, each comprising a voltage regulator, an inductor, an inverter for producing a high frequency square wave current of alternating polarity, an improved inverter voltage clamping circuit, a step up transformer, and an output rectifier for producing a dc voltage at the output of each module. The inputs to the converter modules are fed from a common dc rectifier/filter and are linked together in parallel through decoupling networks to suppress high frequency input interactions. The outputs of the converter modules are linked together in series and connected to the input of the transmission line to the load through a decoupling and line matching network. The dc-dc converter modules are phase activated such that for n modules, each module is activated equally 360.degree./n out of phase with respect to a successive module. The phased activation of the converter modules, combined with the square current waveforms out of the step up transformers, allows the power supply to operate with greatly reduced output capacitance values which minimizes the stored energy available for discharge into an electron beam gun or the like during arcing. The present power supply also provides dynamic response to varying loads by controlling the voltage regulator duty cycle using simulated voltage feedback signals and voltage feedback loops. Circuitry is also provided for sensing incipient arc currents reflected at the output of the power supply and for simultaneously decoupling the power supply circuitry from the arcing load.

  11. E-beam high voltage switching power supply

    International Nuclear Information System (INIS)

    Shimer, D.W.; Lange, A.C.

    1997-01-01

    A high power, solid state power supply is described for producing a controllable, constant high voltage output under varying and arcing loads suitable for powering an electron beam gun or other ion source. The present power supply is most useful for outputs in a range of about 100-400 kW or more. The power supply is comprised of a plurality of discrete switching type dc-dc converter modules, each comprising a voltage regulator, an inductor, an inverter for producing a high frequency square wave current of alternating polarity, an improved inverter voltage clamping circuit, a step up transformer, and an output rectifier for producing a dc voltage at the output of each module. The inputs to the converter modules are fed from a common dc rectifier/filter and are linked together in parallel through decoupling networks to suppress high frequency input interactions. The outputs of the converter modules are linked together in series and connected to the input of the transmission line to the load through a decoupling and line matching network. The dc-dc converter modules are phase activated such that for n modules, each module is activated equally 360 degree/n out of phase with respect to a successive module. The phased activation of the converter modules, combined with the square current waveforms out of the step up transformers, allows the power supply to operate with greatly reduced output capacitance values which minimizes the stored energy available for discharge into an electron beam gun or the like during arcing. The present power supply also provides dynamic response to varying loads by controlling the voltage regulator duty cycle using simulated voltage feedback signals and voltage feedback loops. Circuitry is also provided for sensing incipient arc currents reflected at the output of the power supply and for simultaneously decoupling the power supply circuitry from the arcing load. 7 figs

  12. 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.

  13. The eGo grid model: An open-source and open-data based synthetic medium-voltage grid model for distribution power supply systems

    Science.gov (United States)

    Amme, J.; Pleßmann, G.; Bühler, J.; Hülk, L.; Kötter, E.; Schwaegerl, P.

    2018-02-01

    The increasing integration of renewable energy into the electricity supply system creates new challenges for distribution grids. The planning and operation of distribution systems requires appropriate grid models that consider the heterogeneity of existing grids. In this paper, we describe a novel method to generate synthetic medium-voltage (MV) grids, which we applied in our DIstribution Network GeneratOr (DINGO). DINGO is open-source software and uses freely available data. Medium-voltage grid topologies are synthesized based on location and electricity demand in defined demand areas. For this purpose, we use GIS data containing demand areas with high-resolution spatial data on physical properties, land use, energy, and demography. The grid topology is treated as a capacitated vehicle routing problem (CVRP) combined with a local search metaheuristics. We also consider the current planning principles for MV distribution networks, paying special attention to line congestion and voltage limit violations. In the modelling process, we included power flow calculations for validation. The resulting grid model datasets contain 3608 synthetic MV grids in high resolution, covering all of Germany and taking local characteristics into account. We compared the modelled networks with real network data. In terms of number of transformers and total cable length, we conclude that the method presented in this paper generates realistic grids that could be used to implement a cost-optimised electrical energy system.

  14. Performance analyses of Z-source and quasi Z-source inverter for photovoltaic applications

    Science.gov (United States)

    Himabind, S.; Priya, T. Hari; Manjeera, Ch.

    2018-04-01

    This paper presents the comparative analysis of Z-source and Quasi Z-source converter for renewable energy applications. Due to the dependency of renewable energy sources on external weather conditions the output voltage, current changes accordingly which effects the performance of traditional voltage source and current source inverters connected across it. To overcome the drawbacks of VSI and CSI, Z-source and Quasi Z-source inverter (QZSI) are used, which can perform multiple tasks like ac-to-dc, dc-to-ac, ac-to-ac, dc-to-dc conversion. They can be used for both buck and boost operations, by utilizing the shoot-through zero state. The QZSI is derived from the ZSI topology, with a slight change in the impedance network and it overcomes the drawbacks of ZSI. The QZSI draws a constant current from the source when compared to ZSI. A comparative analysis is performed between Z-source and Quasi Z-source inverter, simulation is performed in MATLAB/Simulink environment.

  15. High voltage systems

    International Nuclear Information System (INIS)

    Martin, M.

    1991-01-01

    Industrial processes usually require electrical power. This power is used to drive motors, to heat materials, or in electrochemical processes. Often the power requirements of a plant require the electric power to be delivered at high voltage. In this paper high voltage is considered any voltage over 600 V. This voltage could be as high as 138,000 V for some very large facilities. The characteristics of this voltage and the enormous amounts of power being transmitted necessitate special safety considerations. Safety must be considered during the four activities associated with a high voltage electrical system. These activities are: Design; Installation; Operation; and Maintenance

  16. Method for controlling an accelerator-type neutron source, and a pulsed neutron source

    International Nuclear Information System (INIS)

    Givens, W.W.

    1991-01-01

    The patent deals with an accelerator-type neutron source which employs a target, an ionization section and a replenisher for supplying accelerator gas. A positive voltage pulse is applied to the ionization section to produce a burst of neutrons. A negative voltage pulse is applied to the ionization section upon the termination of the positive voltage pulse to effect a sharp cut-off to the burst of neutrons. 4 figs

  17. Design of a MEMS Capacitive Comb-drive Micro-accelerometer with Sag Optimization

    Directory of Open Access Journals (Sweden)

    B. D. PANT

    2009-10-01

    Full Text Available The current paper presents an optimization study for the designing of a highly sensitive inertial grade capacitive accelerometer based on comb-drive actuation and sensing. The proof mass, suspension system (beams or tethers, stators and rotors have to be realized through an HAR (high aspect ratio DRIE (deep reactive ion etching process for which process optimization has already been done at our laboratory. As the proof mass is a bulk micro-machined structure having a mass in milligram range, the optimum positioning of the tethers on the proof mass is important to have minimum sag, necessary to reduce the off-axis sensitivity. The optimization for the positioning of the tethers has been carried out using a commercial software tool ANSYSTM Multiphysics. The accelerometer has been modeled analytically to predict its characteristics. The dependency of sensitivity on the dimensions of the suspension beams (tethers has also been verified using the above FEM software tool. The present device has been designed to deliver a high sensitivity of 13.6 mV/g/V for low-g applications.

  18. A study on the simulation and fabrication of three phase multi function power flow controller energized by SMES

    International Nuclear Information System (INIS)

    Kim, A.R.; Kim, J.H.; Kim, H.J.; Kim, S.H.; Seong, K.C.; Park, M.; Yu, I.K.

    2007-01-01

    The harmonic current, which is generated by non-linear switching devices, flows into the utility network, and becomes one of the undesired reasons which lead to the voltage distortion. And voltage sag from sudden increasing loads is also one of the serious problems inside the utility network. In order to compensate these problems, the authors propose a certain active filter system, which includes an SMES coil for energy source. However, since SMES includes the superconducting magnetic coil, quenching problem caused by unexpected reasons is one of the significant factors of the performance of active filter. Finally, this paper shows the results of the analysis of the influences of the internal fault of SMES coil. And the result of the operation of a three-phase multi-function power flow controller for the internal fault of SMES coil is also demonstrated

  19. Simultaneous On-State Voltage and Bond-Wire Resistance Monitoring of Silicon Carbide MOSFETs

    Directory of Open Access Journals (Sweden)

    Nick Baker

    2017-03-01

    Full Text Available In fast switching power semiconductors, the use of a fourth terminal to provide the reference potential for the gate signal—known as a kelvin-source terminal—is becoming common. The introduction of this terminal presents opportunities for condition monitoring systems. This article demonstrates how the voltage between the kelvin-source and power-source can be used to specifically monitor bond-wire degradation. Meanwhile, the drain to kelvin-source voltage can be monitored to track defects in the semiconductor die or gate driver. Through an accelerated aging test on 20 A Silicon Carbide Metal-Oxide-Semiconductor-Field-Effect Transistors (MOSFETs, it is shown that there are opposing trends in the evolution of the on-state resistances of both the bond-wires and the MOSFET die. In summary, after 50,000 temperature cycles, the resistance of the bond-wires increased by up to 2 mΩ, while the on-state resistance of the MOSFET dies decreased by approximately 1 mΩ. The conventional failure precursor (monitoring a single forward voltage cannot distinguish between semiconductor die or bond-wire degradation. Therefore, the ability to monitor both these parameters due to the presence of an auxiliary-source terminal can provide more detailed information regarding the aging process of a device.

  20. Simple, high current, antimony ion source

    International Nuclear Information System (INIS)

    Sugiura, H.

    1979-01-01

    A simple metal ion source capable of producing a continuous, uncontaminated, high current beam of Sb ions is presented. It produced a total ion current of 200 μA at 1 kV extraction voltage. A discharge occurred in the source at a pressure of 6 x 10 -4 Torr. The ion current extracted from the source increased with the 3/2 power of the extraction voltage. The perveance of the source and ion density in the plasma were 8 x 10 -9 and 1.8 x 10 11 cm -3 , respectively