Research on Improved PR Control Strategy for Three-Phase Grid-Connected Inverter Based on LCL Filter

Although the linear control represented by d-q coordinates vector control can eliminate the system steady-state error,there are power coupling problems in the system,which makes the system be difficult to realize stable operation with a unit power factor. A static alpha beta coordinates system based PR control strategy is proposed in this paper based on the traditional current PI control. The PR control has been improved which will reduce complex coordinate transformation. Dynamic contrast simulation show that the improved PR control grid inverter apparatus has good dynamic response performance and can realize no steady-state error tracking current reference value. Moreover,it will quickly track the power grid voltage after the net current mutation so as to realize the decoupling control of active and reactive power. Analysis on harmonic content show that the improved PR control strategy has certain harmonic suppression.