动态电压恢复器的能量稳定控制

针对动态电压恢复器(DynamicVoltageRestorer,DVR)提出了一种能量稳定控制策略,该策略综合了已有的负荷电压固定补偿,同相电压补偿和最小能量补偿三种负荷电压控制策略的优点而避免了各自的缺点,在实现DVR补偿目标的同时,优化了DVR与系统的能量交换过程,减少了所需要的设备容量并增加了有效补偿时间,提高了经济性和可靠性。采用该控制策略的DVR不需要整流充电单元也能够在发生电压跌落或电压上升后的较短时间内恢复其直流储能单元的能量,同时避免了系统电压上升时,DVR吸收能量导致直流侧过电压带来的安全威胁。最后用仿真试验验证了该控制策略的实用性和有效性。     

一种可持续补偿三相动态电压恢复器的研究

针对传统DVR不能补偿持续电压跌落的问题,提出了一种新的动态电压恢复器(DynamicVoltageRe storer简称DVR)结构,采用易于控制的整流电路,将能量从电源提供给DVR,从而实现电压跌落的持续补偿。基于该DVR结构,分析了整个电路的控制方法。实验和仿真结果表明,该DVR可有效地解决电网电压的许多质量问题,保证敏感负载的电压稳定,满足电力负荷对电网电压质量的要求。     

基于有源式混合储能系统的动态电压恢复器

针对电压暂降问题,利用动态电压恢复器(DVR)从超级电容器蓄电池混合储能装置汲取电能补偿负载电压。介绍基于有源式混合储能系统的动态电压恢复器的等效电路,建立了蓄电池电容器并联的数学模型和控制系统,提高整套DVR的工作特性与经济性能比。对有源式混合储能系统用于DVR进行仿真分析,结果表明对于持续时间较长的电压暂降,有源式混合储能系统能有效维持敏感负荷的电压恒定。     

动态电压恢复器主电路拓扑和控制算法的研究

为了改善动态电压恢复器(DVR)的性能从而进一步提高其补偿电压跌落能力,根据国内外DVR的研究动态,对目前应用的DVR主电路拓扑结构、检测策略及电压补偿控制策略做了深入的比较分析,提出了级联多电平DVR。该DVR与传统结构相比,明显提高了各方面的性能,有效解决了实际应用中使用串联变压器作为电压注入方式带来的问题和不足。改进后的"abc-dq"变换算法具有准确、快速的特点,且考虑了系统的补偿策略,能量稳定控制策略综合了其它几种控制策略的优点同时避免了各自的缺点,优化了DVR与系统的能量交换过程,减少了所需要的设备容量并增加了有效补偿时间,提高了经济性和可靠性。随着电力电子技术和控制理论的发展,DVR的性能必将得到更大的提高。     

电能质量问题的研究和技术进展(三) --电力系统的电压凹陷

首先介绍电压凹陷的一般概念。从幅值和持续时间所反映的波形特征上对各种电压凹陷进行分类。基于系统可靠性的分析方法提出电压凹陷影响评估的方式并给出性能指标，考虑了敏感负荷的要求和电压凹陷的量化标准。最后简要介绍了电压凹陷的一般控制方法。     

Voltage sag and swell mitigation based on modulated carrier PWM

The voltage sags or swells which are normally encountered in distribution systems can be compensated by three-phase Direct Voltage Regulators (DVR). In general, when the sag or swell in any phase is sought to be compensated by using the power available in the other phases, extensive signal processing is required, since the magnitudes and phase-angles differ very much. A new control procedure for generating the pwm signals is presented, which is mostly analog and not at all computation-intensive. Illustrations are provided in which the swell or sag can be brought down by using the power either from the other two phases or power from the same phase. The emphasis is not to establish the superiority or otherwise of these arrangements of diverting power from any one phase to the other phase for mitigating the sag or swell. The core of the work deals with the simplicity of the new pwm generation procedure employed for such diversion of power. The feed-forward nature of the control leads to stable operation. Its effectiveness has been demonstrated by simulations.     

A comprehensive review of dynamic voltage restorers

During the last half century the Power Quality (PQ) related problems have become important issues. Many solutions have been proposed to address the PQ problems. The most attractive and flexible way is to use power electronic converter based devices such as Dynamic Voltage Restorer (DVR), Distribution Static Compensator (DSTATCOM), Unified Power Quality Conditioner (UPQC), Uninterruptible Power Supply (UPS), and other devices usually called custom power devices. Among custom power devices, the DVR is the most economical solution to overcome the voltage-related PQ problems. Intensive research has been done in the field of DVR and the field is rather mature now. But, a survey on the published papers showed that there is not any published paper that reviews the DVR technology. This paper tends to provide a comprehensive review on the DVR topologies, control strategies and applications. We will consider all of the fast voltage compensators, i.e. the devices called Static Series Compensator (SSC), sag corrector, Dynamic Sag Corrector (DySC), and other similar devices are also considered. All of these devices will be called DVR since they operate almost in the same way. Some comparative conclusions are also provided. This paper can be beneficial for the researchers and engineers, who want to do investigations on DVRs.     

动态电压恢复器的复合控制策略

动态电压恢复器（DVR）是解决电网电压跌落的一种经济有效的方案。文中在简要介绍DVR原理的基础上,首先分析了目前DVR所用的前馈控制策略和反馈控制策略,然后针对以半桥式逆变器为主结构的DVR,提出了一种由前馈控制、电压瞬时值反馈控制和滤波电容电流瞬时值反馈控制构成的复合控制策略,并推导了系统传递函数,进行了Bode图分析,最后,通过PSCAD/ EMTDC软件仿真和样机实验验证了复合控制策略的合理性和有效性。实验结果也表明复合控制策略能提高DVR系统的动态性能、跟随性和稳定性。     

DVR的不平衡浪涌和过电压控制

讨论无串联隔离变压器的动态电压调节器(DVR)在不平衡电压浪涌或过电压情况下的补偿问题。使用不可控整流为直流侧电容充电的DVR,在补偿时只允许其向系统注入有功功率。在浪涌或过电压发生时,DVR可能发生从系统吸收有功功率的情况,如果仍然使用传统的同相或相位不变电压注入控制方法,将导致直流侧电容电压迅速升高,可能损坏开关器件或储能单元。利用最小能量补偿控制方法也不能完全解决该问题,因而提出一种单向功率流动控制算法。该算法通过将参考电压旋转一定的角度,使DVR无论在3相平衡与不平衡浪涌或过电压的情况下,都不从配电系统吸收有功,同时能将负荷电压补偿为3相平衡且达到正弦的额定值。该算法加入对DVR最大补偿极限的考虑,以确保注入补偿电压不超过DVR的补偿极限。文中对直流母线电压不可避免的泵升问题提出了缓冲控制策略。最后,仿真结果验证了算法的正确性及有效性。     

动态电压恢复器电压跌落检测

动态电压恢复器中常用d-q变换法实时检测电压跌落,但是它的检测精度和实时性易受到三相不平衡情况下负序分量和低通滤波器的影响。提出一种改进的检测方法,首先对三相电压进行微分运算,构造线性方程组实现电网电压中的正、负序分量分离,再对正序分量进行d-q变换,消除负序分量的干扰,最后使用高截止频率低通滤波器滤除其他频次干扰,减少系统延时。理论分析和仿真试验都验证了其可行性。     

补偿约束下动态电压恢复器不对称电压暂降补偿方法

针对补偿电压注入约束下的不对称电压暂降补偿,提出一种新的动态电压恢复器补偿策略。首先以A相为参考相,以各相电压端点为圆心作补偿极限圆,通过旋转B、C相极限圆得到有效补偿域;然后根据有效补偿域与参考电压圆的交角来确定完全补偿弧;最后沿此弧旋转负荷电压,在弧内求取最小能量注入解。该方法简单直观,适用于补偿三相负荷完全对称时由各种故障类型引起的电压暂降。由于此方法无需先抵偿负序和零序分量,通过在有效补偿域内对源电压进行直接计算,最大故障范围内实现负荷电压的对称补偿,且求解过程无循环搜索,响应速度快,满足实际工程应用的需求。     

动态电压恢复器恒相电压补偿仿真

介绍一种三相独立式的动态电压恢复器(DVR),通过采用比例-积分(PI)控制算法对DVR进行恒相位补偿研究,以提高DVR的响应时间和补偿能力。应用Matlab进行系统仿真,仿真结果说明了该方法具有良好的动态性能与补偿效果。     

动态电压恢复器容量与补偿方案关系的研究

动态电压恢复器是解决电网电能质量问题的一种重要手段，该文针对动态电压恢复器串联侧补偿容量与补偿方案、电路拓扑及电网情况的关系进行了理论分析和推导。通过不同拓扑、不同补偿方案、不同电网情况下装置补偿容量大小的比较，从而提出一种适合于动态电压恢复器的电路拓扑和补偿方案。     

动态电压恢复器的检测算法研究

动态电压恢复器(DVR)是补偿电压暂降最经济、最有效的装置。研究DVR 的检测算法是设计DVR最重要和最主要的任务之一。常见的检测算法有每相电压量导数算法、单相电压延迟60°构造三相电压dq 变换法、求导数法构造三相虚拟电压的dq 分解法和两点法。通过对各种检测算法的理论分析和在实际装置上的仿真波形研究, 确定两点法具有原理明确、实现方法简单、计算误差小等优点, 更适合作为工程用DVR 装置的检测算法。     

考虑衰减直流分量的动态电压恢复器补偿量的直接检测方法

针对故障信号中的衰减直流分量影响电压补偿量检测的实时性与补偿精度问题,分别利用三角函数周期性的特点以及三角函数与其导数之间的关系提出了滤除衰减直流分量的半周期算法和三点算法,这两种算法可以从故障信号中快速提取出基波分量,再结合瞬时序分量分解环节提取出基波正序电压分量,然后用直接检测算法求出电压补偿量的大小。仿真结果表明,半周期算法和三点算法都具有实现简单、实时性好的特点,适用于动态电压恢复器的实际应用。     

Compensation of voltage disturbances in distribution systems using single-phase dynamic voltage restorer

In this paper, a new topology is proposed for a single-phase dynamic voltage restorer (DVR) using direct ac/ac converter. This topology does not require dc-link energy storage elements. The proposed topology has a simple structure and can compensate several types of voltage disturbances such as voltage sags, swells, harmonics and flickers. This topology will not face any problem in long time compensation due to the fact that it provides the required energy directly through grid. The proposed topology can be easily extended to n-phase systems such as three-phase based on the same principle of the operation. In n-phase systems, the voltage sags and swells can be properly compensated regardless of the balanced or unbalanced operation. A new control method is also proposed for direct ac/ac converter in the proposed topology. The simulation and experimental results verify the effectiveness of the proposed topology and its control method in voltage restoration.     

基于谐振控制器带谐波补偿功能的DVR

由于电网中电压凹陷发生的时间不多,动态电压恢复器(DVR)通常都处于备用状态。为了提高动态电压恢复器的效率,提出了静止坐标下的谐振控制器,避开复杂的坐标变换方法简单地检测出指定次数的谐波。应用这种静止坐标下的谐振控制器对指定次数的谐波电压进行闭环控制,使DVR具备补偿谐波电压的功能,而对基本DVR的电压凹陷补偿性能的影响很小。还提出了应用δ算子实现谐振控制的途径,提高了DVR的效率。通过M ATLAB仿真表明该方法可以消除指定次数谐波的绝大部分。     

2MVA无串联变压器级联多电平动态电压调节器的设计与仿真

研究了基于级联多电平结构的无串联注入变压器的2MVA动态电压调节器(Dynamicvoltagerestorer,DVR)的系统设计方案,针对DVR的主电路拓扑、电压暂降检测算法、底层载波移相控制策略、储能计算、滤波器设计及逆变器部分的损耗进行了分析研究,并对某生产基地6kV系统的电压暂降问题完成了DVR装置主电路参数和控制电路的功能设计,采用仿真软件EMTDC/PSCAD进行了仿真研究,验证了文中所提设计方案的正确性及有效性。     

基于综合能量最优补偿的动态电压恢复器

为实现动态电压恢复器(DVR)对暂降电压幅值和相位补偿的同时,减少能量的损耗,延长补偿时间,最大程度减小暂降电压对负载的影响,文中提出了一种综合能量最优补偿策略.通过分析综合能量最优补偿过程,得出补偿相量图和解析式,并讨论了该策略的极限补偿问题.分析补偿电压幅值、输出有功与相关物理量之间的数学关系式和关联曲线,得出最优...     

Voltage sag mitigation in an Indian distribution system using dynamic voltage restorer

Now a day’s most power quality problems in distribution systems are related to voltage sags. Hence, diverse solutions have been tried to compensate these voltage sags to circumvent financial losses due to voltage sag at industries. Dynamic voltage restorers (DVRs) are now becoming more recognized in industries to diminish the impact of voltage sags to sensitive loads. The DVR, which is placed in series with a sensitive load, must be able to react speedily to a voltage sag if end users of sensitive equipment are to experience no voltage sags. This paper discusses the use of series reactive injection as a voltage regulator. The proposed approach is to develop analytical aspects and to illustrate these by an example of a real Indian distribution system. Voltage sag can be eliminated by continuously injecting very small voltage profile to the system. The scheme combines the method of instantaneous symmetrical components and complex Fourier transform relations. The proposed technique, based on half-cycle averaging, can mitigate voltage sag at desired locations in distribution systems. The proposed methodology is applied in a 4 bus system and a real Indian distribution system.