基于统一模型的谐波及无功电流检测

Unified model based harmonics and reactive current detection

基于瞬时无功功率理论建立了谐波及无功电流检测系统闭环、开环的统一模型.将负载电流进行坐标变换,在旋转坐标系下经低通滤波得到基波有功电流,从负载电流中减掉基波有功电流获得谐波及无功电流.给出检测电路等效低通滤波器的优化设计方案,分析了等效滤波器的阶数、截止频率对检测系统动、静态特性的影响.结果表明,为了兼顾检测系统动、静态特性的要求,等效滤波器的截止频率应为10～40Hz;为了减小系统的复杂性,等效滤波器的阶数不宜高于三阶.通过电力有源滤波器的谐波及无功电流实时闭环检测系统的实验,结果表明该检测系统具有良好的动、静态响应.

A unified model for harmonics and reactive current closed-loop or open-loop detection was established based on instantaneous reactive power theory. The fundamental active currents were obtained by transforming the load currents into rotation coordinate system and filtering the high frequency component through an equivalent lowpass filter. Harmonics and reactive currents were acquired by subtracting the fundamental active currents from load currents. An optimum project was presented for the equivalent lowpass filter, and the effects of the rank and cutoff frequency of the filter on the dynamic and static features of the detection system were analyzed. Considering the performance of both dynamic and static response, the cutoff frequency should be 10-40 Hz. The rank should not exceed 3 for reducing the realization complexity. The experimental result of a realtime harmonics and reactive current closed-loop detection system applied to active power filter shows that this system has perfect dynamic and static response.