Improved Detecting Method for Harmonics and Reactive Currentsin Single phase Circuits

The low pass filter has great influence on the delay of harmonics detection. An improved detecting method for single phase harmonics and reactive currents is proposed. The low pass filter is replaced by digital integration in a base cycle. It takes only several simple computations to detect harmonics and reactive currents at each sampling point. The detecting delay is fixed at one fundamental cycle. Considering that the harmonics of power systems are mostly odd harmonics, the algorithm is further improved. The integration time is reduced to a half cycle. The computational complexity keeps the same and the detecting delay decreases to a half cycle. The method needs few computations and is easy to be implementd. The validity is verified by simulation results.