Improved harmonic detection algorithm applied to APF

The speed and accuracy of harmonic current detection are the important index of active power filter. Due to the low pass filter, the traditional ip-iq algorithm has the disadvantage of slow detection speed. The paper proposes a variable step size LMS/LMF adaptive filter algorithm. The adaptive filter can not only change the step size according to the change of original signal, but also change the proportion of the Least Mean Square(LMS) algorithm and the Least Four-order Moment (LMF) algorithm, which makes the advantages of high detection accuracy of LMF and high detection speed of LMS fully played. The simulation results show that the proposed algorithm is effective, and the speed of harmonic current is improved obviously.