A Method of Harmonics Current Detection for an Active Power Filter Using pq-Theory and Moving Average High-Pass Filter

Abstract

In a harmonic detection system of active power filters, the pq-theory can be used for the calculation of harmonic current detection. A high pass filter of the first order is usually used for the detection of the ac component of instantaneous real power (p) and instantaneous imaginary power (q). But, in that system transient response for a load change is not high enough. We propose a new detection system in which ac components are derived from p and q using a moving average high-pass filter. By the proposed system, control response and accuracy are very good even in the case of an abrupt load change. The operating performance of the proposed system is confirmed by laboratory model test.