Virtual-Flux based Active Power Filter for Power Quality Improvement

Abstract

This paper presents the application of virtual-flux based control to a shunt active power filter (APF). The shunt active power filter is controlled using virtual-flux based direct power control with space vector modulation (DPC-SVM). The control is implemented with a virtual-flux estimator in place of the grid voltage sensors. The instantaneous power theory is used to estimate the required compensation reactive power, and to estimate the controlled powers of the APF. The virtual-flux estimation is performed using the second order generalized integrator (SOGI), and a virtual-flux phase-locked loop ensures robust grid synchronization of the APF. Simulation results show that when the APF is connected in parallel with a diode rectifier, it improves the quality of the current drawn from the source. The total harmonic distortion (THD) of the source current improved from 26.75% without the APF to 8.95% with the APF.