Control strategies of selective harmonic current shunt active filter

The possible calculation methodologies when designing a selective shunt active filter are presented. To accomplish selective extraction of harmonic sequences, the modulation-filter-demodulation technique is used. The fundamental equations of this method are based on pq theory. Its equivalence with the SRF (synchronous reference frame) method is shown. In order to validate the proposed calculation methods, measured currents from an arc furnace, showing high harmonic distortion, are used. The obtained results show the effectiveness of the proposed method for selective filtering of the undesired current harmonics in a controlled way.