Parallel active filter controlling based on instantaneous compensation of reactive power

Extracting the current reference signal is the heart of a parallel active filter. Regard to time and frequency domain, different methods are presented for it. Pq theory in time and RDFT in frequency domain are two well known of them. This paper proposes a new algorithm by composing these methods and verifies its capability in compensation of harmonics, reactive power and negative sequence of load current even under some non-ideal situations of source, like distortion and unsymmetrical magnitudes of three phase voltages. It is revealed that the algorithm makes filter operation more stable in the case of source voltage deviations in comparison with pq method.