A Novel Harmonic Detection Algorithm Based on Time-varying Observer

Abstract

This paper proposed a novel harmonic detection method for active power filter that the linear time-varying Luenberger observer (LTLO) is utilized for detecting specific harmonic currents in real time. The observer can reduce the calculation amount of traditional harmonic fractional compensation and achieve rapid harmonic detection through a time-varying observer. By embedding the high-frequency current harmonic internal model into the state matrix of the time-varying state observer, the observation error of the state observer can be effectively reduced. By designing a reasonable output matrix, a specific order of harmonics can be observed, which can effectively reduce the capacity of the active power filter. The validity of the proposed observer is proved by Lyapunov-like lemma and Barbalat's lemma. The simulation results demonstrated that the proposed harmonic detection method can achieve accurate estimate specific order harmonic current.