A method of current detection for an active power filter applying moving average to pq-theory

Abstract

The accuracy of harmonic currents detector and characteristics of current controls are important to improve the compensation characteristics of an active power filter. This paper proposes a detector which has high accuracy and good response by applying pq-theory and moving average high-pass-filter (HPF) and good response current control by applying current-deviation code-distinction. A new modified detection system using a moving average HPF whose sampling time is changed according to the source frequency fluctuation is also proposed. The active power filter combining the proposed method of the detector and the current control can compensate harmonic currents which are generated by a three-phase rectifier with a DC filter capacitor with high accuracy and good response.