An Improved Algorithm for Harmonic Current Detection Based on Instantaneous Reactive Power Theory

Fast and precise detection of harmonic currents is the key factor that determines the integrative filtering performance of active power filter(APF).An improved harmonic detection algorithm based on the instantaneous reactive power theory is proposed,in which a new variable step length least mean square(LMS) adaptive filter is used as the low-pass filter in the detection circuit.By means of choosing the parameters of recurrence formula and the autocorrelation estimation of two error signals,the step length can be effectively adjusted,furthermore,the convergence rate and misadjustment can be controlled more flexibly.The theoretical analysis and simulation experiment prove that the proposed harmonic current detection algorithm is correct and effective.