In order to improve the quality of electric energy, active power filter is used to restrain and compensate harmonic current, whose effect is determined by detecting precision and its dynamic response. Considering low Signal-to-Noise ratio of the load current, a novel variable step-size MLMS algorithm for harmonic detection is introduced in this paper, which adds a momentum factor to weights'
... [Show full abstract] recursion formula, and uses the time-average estimation of both present error and past-step error to control the updating the step-size. Through MATLAB simulations and DSP experiments, the performances of the fixed step-size LMS algorithm and the variable step-size MLMS algorithm are analyzed, and both results verify that the latter can provide a fast dynamic response while ensuring high detecting precision. At last, the novel MLMS harmonic detecting method is applied to unbalanced three-phase circuit, whose simulation result verifies its effectiveness.