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     

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。     

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。     

可控电压源型柔性直流输电换流器拓扑综述

为分析不同可控电压源型柔性直流输电换流器拓扑结构的技术特点,围绕模块化多电平换流器（Modular Multilevel Converter,MMC）,建立了基于几种可控电压源型换流器拓扑的柔性直流输电系统电磁暂态模型,结合PSCAD／EM’I＇DC的数字仿真结果,验证了所提出的换流器拓扑结构及其输电方案的可行性。     

基于超级电容器储能的电压暂降补偿分析

就动态电压恢复器和配电静止同步补偿器对电压暂降的补偿技术进行了详细的计算分析，分别通过注入最小电压和注入最小电流确定了装置的最小补偿容量，从而方便装置的设计和控制。同时分析表明，在考虑极端情况即没有超级电容器储能单元时，电压暂降的补偿并不总能实现，因此采用超级电容器作为储能单元的动态电压恢复器和配电静止同步补偿器在提高电能质量方面有重要作用。     

一种补偿电网电压凹陷的DVR优化补偿策略

针对电网中敏感负荷引起的电压凹陷问题,以及提高动态电压恢复器(DVR)的补偿质量,提出了一种优化的综合补偿策略。首先,详细分析了DVR三种基本控制策略的补偿电压与功率流动,推导出最大跌落支持时间;然后,提出了一种跌落前补偿向最小能量补偿过渡的优化综合补偿策略,利用一次过渡曲线将跌落前补偿的电压幅值与相角逐渐过渡到最小能量补偿的值,物理意义明确,减小电压相位跳变的同时增加补偿时间。算例分析结果表明,该法较单一补偿方法显著增加了DVR的补偿时间。仿真结果验证了该方法的有效性。     

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。     

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.     

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。     

动态电压恢复器的时间优化补偿策略研究

动态电压恢复器（DVR）是缓解电压跌落问题最经济、有效的用户电力装置,它的补偿能力指标是持续补偿时间。以补偿电压跌落时DVR装置的最大持续补偿时间为控制目标,通过调整负荷电压超前跌落电网电压的相位角β,提出一种新的时间优化补偿策略。为减轻DVR运行时对负荷的扰动,使补偿开始和结束的暂态过程更平稳,新策略采取了β按恒定步长Δβ缓慢变化的控制方法,并根据DVR装置的T-β曲线,通过判断特定量符号决定β角的补偿方向。此种β角控制方法避免直接求解β的最优解,计算量小。仿真结果证明,新策略能获得比最小能量补偿策略更长的DVR持续补偿时间,有效利用了DVR的直流母线储能。     

不对称故障下考虑电压跌落程度的新能源逆变器控制策略

电网发生不对称故障会影响新能源并网系统可靠运行,严重情况下还会存在切机风险。针对上述问题,提出一种不对称故障下考虑电压跌落程度的电压支撑策略。首先根据逆变器在不对称故障下的输出特性,分析了对公共连接点(point of common coupling, PCC)电压的支撑原理。然后推导了任意不对称故障下PCC电压幅值的通式,进而分析了改变无功电流注入方式的临界点。最后在上述基础上,以逆变器输出电流峰值和已利用容量为约束条件,分别对3种典型的不对称故障进行了分析。确定了每种故障在不同电压跌落阶段的最优无功电流,并推导了各电压跌落阶段的电流参考值计算公式。仿真验证了所提控制策略的有效性与优越性。     

新型动态电压凹陷校正器研究

提出一种基于串并联的动态电压凹陷校正器(DVSC)补偿三相电力系统电压凹陷或隆起新方法,该方法较现有动态电压调节器(DVR)及配电静态补偿器(D-STATCOM)能在大幅降低成本的同时有效地提供保护。该方案基于电压升压变换电路,能够通过升压或降压快速校正电压,其主要特点是具有最小能量储存的单阶功率变换电路。介绍了新型电压控制拓扑、晶闸管旁路开关的交换逻辑。仿真和实验结果证明了该方法的有效性。     

电压瞬时跌落时矩阵变换器控制策略优化

为了解决矩阵变换器(MC)输出电压波形受电网电压瞬时跌落影响的问题,提出了一种针对MC的新型前馈补偿控制。主要功能是根据电网电压变化实时改变调制系数m补偿输出电压波动、减少谐波含量。论文的创新点是在前馈补偿的基础上添加一种电流控制,提高控制精度。最后在输入电压瞬时跌落的情况下,应用Matlab/Simulink软件对MC优化策略进行仿真研究。结果表明该优化策略有效的抑制输出谐波、改善输出电压质量。     

设备侧电压暂降严重程度评估方法研究

综合考虑ITIC曲线、SEMI曲线和C4.110工作组提出的敏感设备耐受曲线,基于严重程度函数单调性和连续性的实际分布特征,分别建立了单相、两相和三相电压暂降影响度函数;在此基础上考虑电压暂降非矩形实测波形,利用多暂降阈值描述改进影响度函数,从而提出了一种考虑电压暂降类型与多暂降阈值描述的多暂降阈值设备侧电压暂降严重程度评估方法,该评估指标综合考虑设备耐受曲线及电压暂降事件的持续时间、暂降幅值、暂降类型和暂降波形评估严重程度。实例分析验证了所提方法的正确性。     

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。     

Capacitance reduction of pulse voltage generator by using series voltage compensator

This paper proposes a new configuration of a pulse voltage generator, which can be applied to the klystron modulator for a large‐scale accelerator. The voltage generator consists of a conventional capacitor discharge type pulse voltage generator and series cascaded voltage compensators. By using the voltage compensators, higher voltage fluctuation of the bank capacitor is acceptable; therefore, its capacitance and the dimensions of the capacitors can be low. This paper discusses the control strategy of the voltage compensators and thyristors for DC voltage supply for the highly fluctuating capacitor voltage, and demonstrates this by a laboratory‐scale experimental setup.     

风力发电用电压跌落发生器研究综述

为测试风力发电系统的低电压穿越能力,需要专门的电压跌落模拟装置。鉴于此,对国内外现有风力发电用电压跌落发生器(VSG)的研究进行了详细的总结,论述了3种形式的VSG实现方法,阻抗形式VSG通过在主电路中并联或串联阻抗模拟电压跌落,变压器形式VSG以变压器组合或中心抽头变压器切换方式模拟电压跌落,电力电子变换形式VSG使用半导体功率器件模拟各种电压跌落类型,功能强大;并对各种方法的工作原理和实现方法进行了分析,对各自的优缺点进行了对比。变压器形式VSG具有结构简单、可靠性高和成本较低的优势,目前使用较多,电力电子变换形式的VSG因其体积小、便于携带和强大的功能,将会得到越来越多的应用。