基于开关表决策的APF与TSC混合系统投切控制方法

针对谐波电流和无功功率威胁电网安全稳定运行的问题，设计基于有源电力滤波器（APF）和多组晶闸管投切电容器（TSC）的混合系统，连续精确补偿电网中的谐波电流和无功功率.针对三相对称型负载的特点，设计电流分频控制方法，按照电流的频率和性质选用独立的PI或PR控制器，达到较高的控制精度.提出基于开关表决策的投切控制方法，在不增加负载电流传感器的条件下，运用多种开关表切换、电流变化率阈值设置和过零检测等手段，混合系统快速精确地预测和投切，有效解决传统固定延时投切方法中暂态响应差、TSC混乱投切等问题.研制37 kV·A样机进行实验，对比基于开关表决策的投切控制方法与传统固定延时投切的实验结果，验证控制方法的有效性.结果表明，基于开关表决策的投切控制方法在不同负载条件下均能获得较好的稳态和暂态特性.
Abstract: A hybrid system composed of active power filter (APF) and multi-group thyristor switched capacitor (TSC) was designed to compensate harmonic current and reactive power, which threatened the safety and stabilization of power system, in grid precisely and continuously. Considering the characteristics of symmetrical loads, the frequency-dividing current control method was used to compensate harmonic and reactive current at high precision, by choosing independent PI or PR controller according to the frequency and property. A switch control method based on switch table decision was proposed to execute precise prediction and switch using switch tables, load current rate and zero-cross detection without adding sensors of load current, so that the problems such as poor dynamic response and disordered switch of TSC in conventional method using a fixed time delay could be solved effectively. A 37 kV·A prototype was developed for the experiment. Comparison between the proposed switch control method and conventional method showed that the proposed method had both good static and dynamic response under different loads.