Advanced Control Strategy Three-Phase Four-leg Shunt Active Power Filter Based on DDSRF-PLL

Abstract

The conventional harmonic and reactive control strategy based on the instantaneous reactive power theory strategy reveals poor performance under distorted and/or unbalanced conditions. In order to overcome this problem, a novel control strategy based on the decoupled double synchronous reference frame (DDSRF) PLL is proposed in this paper. The DDSRF-PLL uses a dual synchronous reference frame and a decoupling network to effectively extract the positive-sequence voltage components in a fast and accurate way, which enables the superior harmonic and reactive compensation for active power filters in the non-ideal conditions. Results obtained by simulations with Matlab /Simulink show that the proposed approach is an effective approach for compensating reactive power and harmonic currents of the load, even if the source voltages are severely distorted and unbalanced.