无锁相环的三相电网谐波和无功检测新方法

A New Detection Method without PLL for Three-phase Circuit Harmonics and Reactive Currents

针对三相电网电压不对称或畸变时存在的缺陷,基于瞬时无功功率理论,本文提出了一种无锁相环的谐波和无功电流检测新方法。该方法利用对称分量法和正余弦变换得到基波正序有功电流,无需对三相电压进行锁相,能准确、实时地检测出不对称三相电网中的基波正序无功电流、负序电流以及谐波电流的和,解决了电网电压畸变和频率发生偏移时锁相环对电流检测准确性的影响。理论分析和仿真结果验证了该方法的可行性。

In order to reduce the error for three-phase voltage asymmetry or distortion,a new detecting method based on the instantaneous power theory is researched in this paper.Fundamental positive-sequence active current can be obtained through symmetric-component method and mathematical transformation.It needs no PLL and can detect the fundamental positive-sequence reactive current,negative-sequence current and harmonic current of the asymmetric three-phase power accurately and efficiently.So the problem of error when frequency offset is solved.Analysis and simulation results illustrate feasibility of the newmethod.