Design method of high performance digital low-pass filter in harmonic detection algorithm

In order to deal with the time domain harmonic detection algorithm of active power filter(APF),a high performance digital low pass filter(HPLPF) was presented,which can satisfy the requirements of dynamic response and filtering accuracy simultaneously.Infinite impulse response filter(IIR) and moving average filter(MA) were analyzed and compared.Then the HPLPF was introduced by cascaded MA filter and Butterworth filter optimally.The proposed high performance filter can fully use Butterworth filter to achieve more precise filtering results and improve dynamic response by using MA filter with its narrow transition zone and fast dynamic response.Simulation results show that the proposed HPLPF meets the demand of time domain harmonic detection algorithm better under the complex harmonic currents situation with inter-harmonics currents.