三相四线制有源电力滤波器谐波及无功电流综合补偿算法

Algorithm of Harmonic and Reactive Current Comprehensive Compensation for Three-phase Four-wire Active Power Filter

并联有源电力滤波器(APF)通常从负载侧检测谐波电流作为APF的指令电流,由于谐波电流变化率较大,且APF本身也会产生附加谐波,使得APF补偿精度不高。针对APF存在的问题,本文提出一种基于瞬时无功理论的三相四线制并联APF综合补偿算法,采用特定次谐波检测算法从网侧检测计算谐波电流及零序电流,从负载侧检测计算负载无功电流及负序基波电流,三相桥臂与零序桥臂解耦后采用无差拍控制实现对谐波及无功的综合补偿。补偿后电网谐波电流含量低,电流与电压相位差很小,中线电流接近零,动态响应快且不论负载对称或不对称都适用,实验结果证明了本文控制策略的有效性。

The harmonic current detecting from load side is usually taken as reference current for shunt active power filter,but the compensation accuracy is low because of the large variant rate of harmonic current and the additional harmonic generated by the APF itself.A comprehensive compensation algorithm for three-phase four-wire active power filter based on instantaneous reactive power theory is proposed to solve the above problems for APF,based on which the specific harmonic detection algorithm is adopted to detect the harmonic current and zero sequence current from grid side,and the reactive current and the negative sequence current is calculated from load side,then the comprehensive compensation of harmonic current and reactive power is realized by the deadbeat control through decoupling of three-phase bridge and zero sequence bridge.After compensation,the content of harmonic current is low,the phase difference between current and voltage is small,the current in neutral line is close to zero,and the dynamic response is fast.Furthermore,this method is applicable for system with symmetry or asymmetry load,and the experimental results prove the effectiveness of the proposed control strategy.