基于分布式电网中DVR的补偿控制策略研究

针对动态电压恢复器（Dynamic Voltage Restorer, DVR）在分布式电网中补偿电压暂降出现的延时和控制不稳定等问题,本文提出一种无串联变压器型DVR的预测电压控制策略,该控制方法采用离散模型为一个电压源逆变器和一个用于开关控制逆变器结合生成一个接口滤波器。 在不需要任何线性控制器或调制技术下,通过DVR跟踪参考电压有效预测控制,保持负载电压在各种电压扰动下稳定输出正弦电压值。在DVR补偿控制策略方面,采用最小有功功率补偿控制策略,该方法更为有效地延长DVR补偿时间,降低DVR输出的有功功率,仿真分析与实验结果验证了所提方法的可行性。     

基于飞轮储能单元的动态电压恢复器优化补偿方法研究

配电系统中的电能质量问题一般与电压暂降有关,而飞轮储能装置具有效率高、功率大等特性,可用来解决电能质量问题。本文用一种基于飞轮储能系统的动态电压恢复器（DVR）解决配电网电压暂降问题,建立含飞轮储能单元并联型DVR模型,重点分析并联型飞轮储能系统的工作模式及相对应的充放电控制策略。配电网中DVR模型主电路采用混合级联H桥拓扑结构,在补偿控制策略方面,提出一种优化补偿控制策略,该方法可以减少所需注入DVR的有功功率和延长系统的补偿时间。通过仿真分析与实验验证,表明了所提模型以及相关补偿控制方法可行性和有效性。     

基于广义积分器的DVR控制策略研究

针对动态电压恢复器（DVR）电压跟踪控制,将广义积分器引入DVR中,克服了传统PI控制器的缺点,实现了电压无差跟踪控制。为了得到良好的补偿效果,采用电容电流内环、电压外环控制的双环控制策略,在推导出系统传递函数的基础上,用Bode图分析了系统对参考电压的跟踪性能以及对负载电流扰动的抑制。实验结果验证了控制策略的有效性和鲁棒性。     

基于飞轮储能的新型动态电压恢复器的研究

提出一种基于飞轮储能的新型动态电压恢复器(DVR),其可对深度电压暂降进行补偿;大功率、高储能量的飞轮储能单元成本高昂,为提高飞轮的总储能量,采用飞轮储能阵列,各台飞轮储能单元并联连接于同一直流母线.详细分析该系统的工作原理和各部分的控制策略;对飞轮储能阵列运行于放电状态的控制策略进行了研究,提出了一种新型的放电控制策略.最后利用Matlab/Simulink对系统进行仿真,验证了所提拓扑结构及控制策略的可行性.     

基于PSpice的动态电压恢复器研究

随着现代电力电子设备的广泛应用,电压跌落已日益成为电力部门和用户关注的电能质量问题。介绍了减少电压跌落的几种方法,分析了采用动态电压恢复器(Dynamic Voltage Restorer)的优点,重点研究了DVR的核心单元基于全控器件的电压源逆变器,及其实现原理,并对设计电路进行了PSpice仿真,仿真结果表明逆变器的输出是符合DVR的要求的。     

动态电压恢复器同步基准正弦电路设计实现

根据同步基准正弦电路在动态电压恢复器(Dynamic Voltage Restorer,DVR)中的应用特点,确定了其实现的原理框图.基于Pinteus的产品设计方法和流程,对框图中的模拟、数字电路部分通过软件仿真验证了理论计算结果.选择I2C总线接口的AD5241,在可变增益放大环节中,采用单片机编程的方法实现了"把模拟器件放到总线上"的全新设计理念.给出了当输入信号中有谐波含量、电压渡动时的输入、输出和反馈电压仿真结果波形,波形显示该电路达到了设计要求.     

一种快速动态响应的 ＬＬＣ 变换器控制策略

为了提高LLC变换器动态响应性能,采用一种新颖的谐振电压控制策略,克服了传统单电压环控制模式下的环路补偿复杂、动态响应能力不足的缺陷,简化控制环路设计,提高动态响应性能。在阐述该控制策略与工作机理的基础上,通过理论分析与原理样机对比试验分析可知,变换器在负载动态过程中的输出电压超调量由1.0%降为0.375%,动态调节时间由1ms缩短为500μs,从而验证了该控制策略具有良好的动态响应能力。     

基于三相电压追踪法的动态电压恢复器仿真研究

电力系统中电压骤升或骤降、电力谐波、三相不平衡等状况都可能导致电子、电机设备无法工作,甚至损坏。动态电压调节器,能在1~2毫秒之内产生补偿电压,抵消系统电压所受干扰,使负荷侧电压感受不到扰动,保证了敏感负荷的安全可靠运行。文章设计了一种基于三相电压追踪法的动态电压恢复器,采用MATLAB/SIMULINK建立仿真模型,仿真结果表明在电压发生骤降时,可以有效补偿电压损失,保证输出电压的稳定,证明了该方法的有效性。     

变流负荷供电线路电压暂降的治理研究

以变流装置驱动的敏感负荷对供电质量要求较高,供电电压质量中存在的电压暂降,可造成调速电机群停事故,所带来的经济损失常在数以百万元以上。结合某拉丝生产工艺线治理电压暂降,消除生产隐患的需求研制出一种采用分相补偿结构,分相控制,三组逆变单元相互独立运行的动态电压恢复器。研制过程中对此设备主电路构成、参数计算、控制方法等方面进行了研究和探讨,通过现场运行验证了设计的正确性。     

高性能价格比功率因数校正系统的动态非线性控制策略

本文建立升压型开关变换器大信号平均电路模型 ,从动态输入输出电压关系 ,提出一种无需乘法器 /除法器、无需电流环放大器、无需测量输入电压的新型非线性控制策略 ,具有高功率因数、高控制精度和快速的动态响应等优良性能 ,计算机仿真和实验验证了这一思想 .     

Virtual impedance control for a regional dynamic voltage restorer

A dynamic voltage restorer (DVR) can be installed in a middle-voltage (MV) power grid, to concurrently protect a cluster of sensitive loads from voltage sags. To further improve its efficiency and reduce the difficulty in its implementation, a novel control strategy for operating such a DVR as a virtual impedance in series with sensitive loads is proposed in this paper. In addition to its usual function of compensating for voltage sags, such a DVR can also operate as a virtual inductance, to function as a fault current limiter (FCL) during a downstream fault, or a virtual capacitance, to function as a series compensator (SC) to compensate the voltage loss along the feeder line during heavy load. Based on a dual-loop control design, strategies for operating a DVR as a series virtual inductance and a virtual capacitance are proposed, and methods for tuning the parameter values and a stability analysis of the whole system are presented. The feasibility and effectiveness of the proposed method are verified by simulations using the PSCAD software, and experimental results obtained using a prototype DVR are presented.     

Development of a 10-kV regional compensation dynamic voltage restorer with multiple functions

The first 10-kV regional compensation dynamic voltage restorer (DVR) has been installed in a 110-kV substation in Shenzhen power grid, to protect plenty of sensitive loads in a wide area simultaneously from the disturbances caused by voltage sags. The location selection and performance indicators of the DVR are determined based on the voltage sag statistic results in recent years of Shenzhen power grid. The implementation schemes of main circuit elements, such as the energy storage unit, inverter and LC filter are presented. To further improve the DVR’s cost-effectiveness, a novel virtual impedance control strategy is proposed to provide the DVR with a function of a Fault Current Limiter (FCL) or a Series Compensator (SC) besides the function of voltage sag compensation. Simulation and field experimental results are provided to show the correctness and effectiveness of the main circuit design and control system development of the 10-kV DVR.     

Design and performance of dynamic voltage restorer using genetic algorithm

In the present scenario, sensitive loads suffer nearly 80% of power quality problems especially due to voltage sag. Dynamic voltage restorer (DVR) finds its perfect application as a compensator to mitigate the voltage sag problem. In this paper, source voltage suffers voltage sag of 30% and load terminal voltage is regulated using proportional and integral (PI) controllers. Synchronous reference frame algorithm is adopted to generate reference load voltage for voltage source converter switching. Optimised values of the gains of PI controllers are achieved using genetic algorithm. Control strategy of the DVR is simulated using MATLAB software and performance of DVR is studied.     

Four-wire dynamic voltage restorer based on a three-dimensional voltage space vector PWM algorithm

A modified voltage space vector pulse-width modulated (PWM) algorithm for a four-wire dynamic voltage restorer (DVR) is described. The switching strategy based on a three-dimensional (3-D) /spl alpha//spl beta/O voltage space is applicable to the control of three-phase four-wire inverter systems such as the split-capacitor PWM inverter and the four-leg PWM inverter. In contrast to the conventional voltage space vector PWM method, it controls positive, negative and zero sequence components of the terminal voltages instantaneously. Three 3-D modulation schemes are analyzed with respect to total harmonic distortion (THD), weighted total harmonic distortion (WTHD), neutral line ripple and switching loss over the whole range of the modulation index when the DVR experiences both balanced and unbalanced sags with phase angle jumps. Experimental results from a 9 kW DVR system using a split-capacitor PWM inverter are presented to validate the simulation results.     

A Novel Technique to Compensate Voltage Sags in Multiline Distribution System—The Interline Dynamic Voltage Restorer

The dynamic voltage restorer (DVR) provides a technically advanced and economical solution to voltage-sag problem. As the voltage-restoration process involves real-power injection into the distribution system, the capability of a particular DVR topology, especially for compensating long-duration voltage sags, depends on the energy storage capacity of the DVR. The interline DVR (IDVR) proposed in this paper provides a way to replenish dc-link energy storage dynamically. The IDVR consists of several DVRs connected to different distribution feeders in the power system. The DVRs in the IDVR system share a common energy storage. When one of the DVR compensates for voltage sag appearing in that feeder, the other DVRs replenish the energy in the common dc-link dynamically. Thus, one DVR in the IDVR system works in voltage-sag compensation mode while the other DVRs in the IDVR system operate in power-flow control mode. In principle, IDVR can operate effectively when constituent DVRs are electrically (not necessarily physically) far apart. Closed-loop load voltage and current-mode-control techniques are used as the control strategy in the two modes of operation. Experimental results obtained for a laboratory prototype of the IDVR are presented to show the effectiveness and the efficacy of the proposed IDVR system to improve power quality     

Performance analysis of dynamic voltage restorer using improved PSO technique

ABSTRACT

This paper has discussed the study of the performance of dynamic voltage restorer (DVR) taking different voltage sag conditions in the supply voltage of the distribution system for linear and non-linear load. DVR is employed to mitigate the voltage sag. Proportional and integral (PI) controller is used for the control of DVR to mitigate the voltage sag. Synchronous reference frame theorybased control algorithm has been implemented for generating reference voltages. In this paper, an efficient improved particle swarm optimisation technique for optimizing the gain parameters of the PI controller has been proposed. The performance and suitability of DVR is validated through MATLAB simulation results and use of Sim Power Systems Blocksets. Integral squared error is implemented to check the performance and suitability of DVR. Extensive results of the proposed method are presented and compared with conventional Ziegler Nichols and genetic algorithm methods of tuning gain parameters of PI controllers.