Control of Three-Phase Power Electronic Converter With Power Controllers in Stationary Frame

Abstract

This article concentrates on a three-phase power converter control system that uses voltages and currents in a stationary reference frame. The advantages of such a control system include the lack of transformation between stationary and rotating reference frames and hence, there is no need for an extra algorithm such as a phase-locked loop for the grid voltage phase-angle determination, as the power components are the same in every coordinate system. The method proposed in this article uses proportional-resonant-integral controllers for tracking referenced Akagi's instantaneous power components, which contain intentional oscillations of double grid frequency. Thanks to that, the sinusoidal converter current is maintained despite the negative sequence component in grid voltage. Different targets for converter current asymmetry, from corresponding, through symmetrical, to opposite to voltage asymmetry may be achieved, depending on the operation mode and the demanded power. Moreover, the power limitation method allowing limitation of the phase-current amplitude even for unbalanced phase currents was applied.