基于重复PI控制和前馈控制的静止无功发生器

Static Var Generator Based on Repetitive PI Control and Feedforward Control

分析了以三相电压型逆变器为主电路结构的静止无功发生器(SVG)的工作原理。针对传统比例积分控制(PI)的局限性,提出了采用重复PI控制和电网电压前馈控制的复合控制策略。重复PI控制结合PI控制和重复控制的优点,提高了系统的稳态和动态性能,能有效改善装置的基波无功补偿准确度,消除稳态误差,改善补偿电流的波形质量。同时,为了抑制电网扰动,引入电网电压前馈控制,使系统近似为一个无源跟随系统,有效消除了网侧电压波动对SVG运行的干扰,抑制了直流侧电容的电压波动。在此基础上,进行系统的仿真建模和实验研究,仿真和实验结果验证了所提控制策略的正确性和可行性。

The working principle of static var generator （SVG） device based on three-phase voltage source inverter （VSI） is analyzed. Due to the limitations of conventional PI controller, repetitive PI control and voltage feedforward control strategies are introduced into SVG system in this paper. Combined with the advantages of PI control and repetitive control, the repetitive PI control increases the performance of steady and dynamic states. It can also enhance the accuracy of the fundamental compensation, eliminate steady state error and improve the waveform quality of compensation current effectively. Meanwhile, in order to suppress the grid disturbance, the grid voltage feedforward control is presented. The system then becomes an approximately passive following system, which limits the interference from grid voltage fluctuation on SVG running and suppresses the capacitor voltage fluctuations of DC side. The modeling simulation and experiment are completed, and the results prove the control strategy correct and feasible.