一种改进复合重复控制在级联STATCOM中的应用

Application of an Improved Compound Repetitive Control in Cascaded STATCOM

比例控制与重复控制相结合的电流控制策略能使静止同步补偿器(STATCOM)在实现无功补偿的同时,提高对谐波的跟踪精度。然而在动态过程中,由于重复控制器存在延迟环节,控制器输出滞后1个工频周期,STATCOM输出补偿电流畸变。为此,本文研究了以LCL滤波器为被控对象的复合重复控制策略,在分析复合控制原理的基础上,给出控制器的设计方法。然后提出一种改进重复控制策略,利用重复内模以工频周期为单位调节的特点,采样当前给定电流和1个周期前给定值,在负载波动时,根据指令值调节重复控制器输入,消除补偿电流畸变,提升动态性能。仿真结果验证了控制系统的有效性。

The current control strategy which combines proportional controller with repetitive controller for static synchronous compensator （STATCOM） is able to realize the compensation of reactive power and improve the tracking accuracy of harmonic. However,the fundamental delay caused by the repetitive controller makes the output lags a power cycle and grid currents distortion in the dynamic process. This paper firstly studies the basic theory of compound repetitive controller with control object of LCL filter, and presents the method of designing regulator in detail. On basis of this, in order to improve the dynamic performance of system, an improved repetitive control strategy is designed by using the characteristic of repetitive control which adjusts with power cycle as a time unit. The input of repetitive controller is aut- omatic modulated according to the given current presently and one base cycle before. It can effectively eliminate the current distortion and improve the dynamic performance. Finally, the simulation results ver- ify the effectiveness of the control strategy.