PLL-Less Active and Reactive Power Controller For Three-Phase Grid-Connected Power Converters

Decoupled active and reactive power controllability is one of the important requirements for grid-connected power converters. The majority of traditional power control methods are based on synchronous reference frame transformation with a Phase-Locked Loop (PLL) to estimate the phase angle. This creates additional drawbacks to the system and makes the control process complicated. In this paper, a PLL-less three-phase grid-connected converter is controlled with Proportional-Resonant (PR) current controllers in the stationary reference frame. Compared with traditional power control methods for three-phase grid-connected power converters, the proposed control scheme has higher reliability and is robust under different distorted power grid conditions. Since the controller is implemented in the stationary reference frame, the control algorithm has a simpler structure. Both simulation and experimental results verify the performance of the proposed controller.