任意负载条件下动态电压恢复器的复合谐振控制策略

Compound Resonant Control for Dynamic Voltage Restorers Under Arbitrary Load Conditions

针对传统比例–积分(proportional-integral,PI)反馈控制器应用于动态电压恢复器时存在稳态误差较大、负载适应性差、难以对非线性负载进行电压补偿等问题,提出一种任意负载条件下的动态电压恢复器(dynamic voltage restorer,DVR)控制策略。该控制策略利用谐振控制实现对负载的无静差电压补偿,结合前馈控制来提高系统的动态响应速度。针对非线性负载在DVR串接电容上产生的谐波电压问题,引入一种电容谐波电压的抑制方法,该方法实时检测电容谐波电压所对应的谐波电流成分并控制DVR产生反向的谐波电流,间接消除了DVR输出电压中的谐波成分,显著提高了动态电压恢复器对任意负载特别是对非线性负载的电压补偿能力。实验验证了所提控制策略的有效性。

One of major problems when apply the proportional-integral method （PI） to the control of dynamic voltage restorers （DYR） is that the PI controller performs a considerable steady error and can＇t maintain stability when load changes. A novel control scheme which based on resonant control and feedforward control has been explored in this paper. The basic principle of this control scheme stems from the zero-steady error characteristic of resonant controllers when applied it to the trace reference signal of certain frequency. Feedforward control of the reference signal has been used to improve the dynamic performance of DVR. This paper also deals with the compensation problem considering nonlinear loads, A novel method to suppress harmonic components which stem from nonlinear load has been presented. The principle of this method is to suppress harmonic currents of capacitors by DVR to eliminate harmonic components of output voltages. Due to the ability to suppress the harmonic component of output voltages, DVR outperforms better compensate ability than traditional PI controller even load current is severely distorted. Experimental results verify the viability and effectiveness of the proposed control scheme.