Effective operation method by interdependent use of condenser energy of the voltage transient sag compensator with controlled gradational voltage

This paper presents the efficient operation method of the interdependent use of condenser energy on the new concept of voltage transient sag compensator. This compensator consists of the series connection inverter units, and each inverter unit generates a different output voltage by 2ⁿ times. The method proposed here, in any case of various levels of transient voltage sags on the power line, provides the efficient use of condenser energy of all these inverter units. The method of interdependent use of condenser energy is also verified by the experiment. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 154(3): 56–64, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20290     

A pulsed power supply with sag compensation using controlled gradational voltage

A pulsed power supply with sag compensation using controlled gradational voltage to increase the flatness of output waveforms has been developed. The sag compensation circuit consists of compensation units connected in series. Each compensation unit consists of capacitances, diodes, and semiconductor switches. The capacitances of each unit are charged with different voltages by 2ⁿ(V₀,2V₀,4V₀,…). The compensation voltage, which has 2ⁿ?1 steps, is generated by switching the semiconductor switches of each unit in a binary sequence. Using this method, compensation voltage waveforms up to 6.2 kV with 31 steps can be obtained with five compensation units. The sag compensation circuit has been adapted to a direct switch‐type pulsed power supply, which generates 7 kV pulsed voltage with a pulse width of 700µs, thus realizing sag compensation. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 150(4): 54–63, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20017     

STATCOM using the new concept of an inverter system with controlled gradational voltage

This paper presents the STATCOM using the new concept of an inverter system which consists of three inverter units connected in series, and each inverter unit generates a different input voltage such as V_C, 2V_C, 4V_C. This inverter system can output a high‐quality voltage by a low‐frequency switching operation. Thus, it can combine low loss and high quality. In this paper, we show the technique to apply STATCOM which uses the inverter system, and examination results. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 168(4): 58–65, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ).DOI 10.1002/eej.20823     

Control of fault current limiter by series‐connected voltage sag compensator

This paper describes a control scheme of fault current limiter by series voltage injection. The current limiter proposed in this study is based on the use of a SMES‐based series‐connected voltage sag compensator, which has been previously studied by the authors, for controlling fault current caused by short circuit on the load side. An algorithm for fast discriminating between power system voltage sag and load‐side short circuit is proposed for the equipment to correctly function either for voltage sag compensation or for fault current limiting purpose. Furthermore, a new control strategy based on output voltage phase control of the series compensator is proposed for current limiting with good waveform characteristics and low active power absorption. Experimental results demonstrated the validity of the proposed strategy. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 155(2): 64–72, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20128     

电压跌落检测的仿真研究

电压跌落是电能指标中的一项重要因素。电能质量的优劣对电网和电气设备的安全、经济运行,保证产品质量和科学实验以及人民生活和生产的正常进行均具有十分重要的意义,直接关系到国民经济的总体利益。而论文研究了电压跌落的产生原因,并阐述了其检测和动态补偿技术,通过Matlab中的simulink进行仿真,从而验证了该种方案的有效性。     

An optimized compensation strategy of DVR for micro-grid voltage sag

Owing to various characteristics of the voltage sag, it is difficult to satisfy requirements of compensation quality and time by using single compensation method. Furthermore, high-power consumption of the phase jump compensation increases the size and cost of a dynamic voltage restorer (DVR). In order to improve the compensating efficiency of DVR, an optimized compensation strategy is proposed for voltage sag of micro-grid caused by interconnection and sensitive loads. Firstly, the power flow and the maximum compensation time of DVR are analyzed using three basic compensation strategies. Then, the phase jump is corrected by pre-sag compensation. And, a quadratic transition curve, which involves the injected voltage phases of pre-sag strategy and minimum energy strategy, is used to transform pre-sag compensation to minimum energy compensation of DVR. The transition utilizes the storage system to reduce the rate of discharge. As a result, the proposed strategy increases the supporting time for long voltage sags. The analytical study shows that the presented method significantly increases compensation time of DVR. The simulation results performed by MATLAB/SIMULINK also confirm the effectiveness of the proposed method.     

模块化多电平动态电压恢复器的研究

提出了一种新型模块化多电平动态电压补偿器(Modular Multilevel Dynamic Voltage Restorer,MM-DVR),对其工作原理进行了介绍,对单相模块化多电平换流器的组成和工作特性进行了分析。对几种常用的补偿策略进行了对比介绍,对所采用的最小电压补偿策略的原理和实现方法进行了阐述,介绍了所采用的瞬时电压dq分解电压暂降检测法的工作原理和应用优势。对比目前常用的换流器调制策略,介绍了最近电平逼近调制方式,并分析了最近电平逼近调制方式在动态电压恢复器应用中的优势。通过在PSCAD/EMTDC环境下搭建的仿真模型对模块化多电平动态电压恢复器的工作特性和补偿效果进行了验证。     

基于飞轮储能的动态电压恢复器补偿策略的研究

针对目前无储能装置动态电压恢复器(DVR)的不足,研究了基于飞轮储能的新型DVR系统。文中介绍了系统的拓扑结构和工作原理;结合飞轮储能装置的特点对补偿策略进行了分析比较,指出综合补偿策略在考虑注入补偿电压能力的同时,优化了DVR与电网的能量交换过程,延长了有效补偿时间;为了克服以往综合补偿策略在求解相量角α时计算量大和不考虑能量倒灌的缺点,通过对输出有功功率-相量角(PDVR-α)曲线和视在功率-相量角(SDVR-α)曲线的分析,提出了一种新型的α求解方法;仿真结果验证了理论分析的有效性和正确性。     

三相动态电压恢复器的主电路研究

针对以往研究的三相动态电压恢复器 ,提出基于三相电压型逆变电路的动态电压恢复器 ,并分析其主电路拓扑 ,提出主电路几项参数的设计方法 ,同时对比不同变压器接法对参数和电路性能的影响。对变压器星形连接和三角形连接的DVR进行了MATLAB仿真 ,并采用变压器星形连接的结构进行了实验。仿真和实验结果验证了参数设计方法和不同变压器接法对动态电压恢复器性能的影响。     

基于正弦函数模型的电压暂降检测算法

为解决电压暂降问题,动态补偿技术是其最终途径,而准确检测出电压暂降的主要特征量是电压暂降补偿的前提.并且检测装置需采取滤波处理措施以减少非基频信号的影响.将基于正弦函数模型的算法应用于电压暂降检测方法,采用图基低通数字滤波器进行数字滤波,且对其检测结果进行分析,并提出了一种基于正弦函数模型的改进方法.仿真结果证明了该方法的有效性.     

Configuration of a voltage sag compensator by use of a micro‐SMES and experimental results

A voltage sag compensating using a micro‐SMES is presented. Based on previous works, we have carried out experiments for voltage sag compensation on the laboratory‐built system in order to validate the proposed minimum energy injection voltage sag compensation algorithm. To improve the compensating performance of the system, two‐degree‐of‐freedom voltage control is proposed. In this paper, the circuit configuration and feedback voltage control system of the compensator are described and the experimental results are reported. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 148(2): 84–92, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10267     

固态限流器对电力系统瞬间电压跌落的影响

电网结构日趋复杂，系统短路容量急剧增加，研究故障情况下提高电压稳定性对于系统安全运行具有重要意义，固态限流器在系统正常运行条件下对外不呈现阻抗，当系统发生短路故障时迅速串入系统网络中。对母线电压具有强支撑作用，利用耦合式三相固态限流器，对2种典型电网系统模型发生故障情况进行了仿真分析。研究表明：固态故障限流器的应用能够有教抑制短路故障引发的系统瞬间电压跌落，而且随着限流阻抗值的增大，相应的改善效果更为明显。这也显示改善系统故障电压是故障限流器具有的一种本质能力。     

Development of voltage sag compensator and UPS using a flywheel induction motor and an engine generator

Flywheel energy storage systems are attracting attention as uninterruptible power supplies (UPS) from the viewpoint of environmental friendliness and high durability performance. Using a low‐speed, heavy flywheel and a low‐cost squirrel‐cage induction motor/generator, two applications are proposed: (1) an 11‐kW voltage sag compensator using a capacitor self‐excited induction generator without semiconductor converters and (2) a UPS composed of the flywheel system and an engine generator. Based on experimental results, an ideal voltage sag compensator and UPS are realized by the low‐technology flywheel system. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 167(1): 74– 81, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20784     

火电厂给煤机变频器电压暂降抗扰力

随着火电厂辅机系统变频器的大规模使用,电网电压暂降引起大量火电机组跳闸的问题凸显。结合陕西电网典型火电机组给煤机变频器低电压穿越特性试验现场试验数据,系统地分析了电压暂降主要因素对变频器输出特性的影响,提出采用动态电压恢复器（dynamic voltage restorer,DVR）进行电压暂降快速补偿的方案。电网电压暂降深度、电压暂降持续时间、负载大小、电压暂降类型等因素对火电机组给煤机变频器工作特性影响较大,导致电压敏感设备变频器直流工作电压降低超限甚至失压,进而引发变频器工作回路动作跳闸退出运行。利用PSCAD/EMTDC搭建典型的变频器电压暂降实验及补偿模型,结果表明采用动态电压恢复器能够很好的稳定变频器直流工作电压,有利于提高变频器电压暂降抗扰能力。     

DSTATCOM在电压凹陷抑制中的仿真研究

电压凹陷是造成供电质量下降的重要原因之一,采用加装STATCOM进行补偿可以有效地提高现代电力系统电压的稳定性.对电压凹陷进行了分析,在此基础上对DSTATCOM在电压凹陷的工况下提出了一种对补偿电流和负载电压进行分别调节的补偿控制策略,对电压敏感负载可起到有效的保护作用.仿真结果验证了该控制策略的正确性和的有效性.     

基于不对称级联型多电平逆变器的动态电压恢复器研究

提出了一种基于不对称级联型多电平逆变器(ACMI)的动态电压恢复器(DVR)及其控制策略。该DVR在结构上采用不对称级联型多电平逆变器,易于实现装置的大容量化;控制策略上先采用跌落前电压补偿法,然后平缓过渡到同相位电压补偿法,在这种控制策略下,系统电压发生幅值和相位跳变时,能够保证负载电压平滑无突变,减小了对相位突变敏感负荷的影响,补偿效果接近跌落前电压补偿法,而所需补偿的能量与同相位电压补偿法接近。Matlab仿真试验验证了该系统结构和控制策略的实用性、有效性。     

Voltage sag compensation with minimum energy injection by use of a micro‐SMES

This paper presents a method to compensate voltage sags with minimum energy injection for a series‐connected voltage restorer using a micro‐SMES. A circuit for extracting the fundamental symmetrical components from sag voltages and a minimum energy injection algorithm is described. Simulations of voltage sag compensation have been carried out using PSCAD/EMTDC for various faults. The simulation results confirm the validity of the proposed method and show the possibility of reducing the size of energy storage devices. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 141(3): 70–80, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10047     

基于DSP的电压暂降检测方法研究

电压暂降是一种严重的电能质量问题,基于DSP电能质量在线监测装置可以对电压暂降进行实时的检测分析。介绍了电压暂降幅值的检测方法,研究了有效值检测方法、瞬时电压dq分解法以及其改进后的αβ-dq变换检测法,并将其在DSP中进行验证,验证结果证明了这几种检测方法的有效性。这些方法均在检测上存在一定的延时,研究发现,不同的暂降深度对应的检测延迟时间有所不同,通过计算得出了电压暂降起始时刻的延时误差曲线,可以利用该曲线进行误差修正,进而得到更为准确的电压暂降起始时刻。仿真结果证明了该曲线能够修正误差时间。     

分布式发电对电压跌落及失电损失分摊的影响

总结了分布式电源对电压跌落的影响,并提出了电压跌落引起的失电损失的分摊方法.采用真实网络作为算例,计算了不同故障类型发生时的电压跌落,最终得出了分布式电源注入功率、接入位置变化对电压跌落的影响,并提出了一种新的失电损失发电侧分摊方法:采用IDGVS指数用于量化分布式电源对电压跌落的影响,从而确定每个分布式电源所应该分摊的电压跌落失电损失费用.     

Flywheel size design considerations and experimental verification using a 50‐kW system for voltage sag compensator with flywheel induction motor

Flywheel energy storage systems can be used as an uninterrupted power supply system because they are environmentally friendly and have high durability. The use of a simple voltage sag compensator with a low‐speed heavy flywheel and a low‐cost squirrel‐cage induction motor/generator is proposed. First, the ability of the proposed system to maintain the load voltage at 100% when the grid is experiencing voltage sag is validated experimentally. Next, design guidelines for the flywheel stored energy are discussed. Experimental verification of a 50‐kW‐class system is carried out, and the results show good agreement with the developed design guidelines. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 181(1): 36–44, 2012; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.21252