Grid-connected control for single-phase inverter based on synchronous frame transformation

Traditional synchronous frame PI control is widely used in grid current control of three-phase inverters to achieve zero steady-state error. However, it can't straightforward be applied to single-phase system. In this paper, imaginary component is built and processed by Park transformation, which changes the AC component into DC component. Therefore, a simple PI control can eliminate the steady-state error of the grid current. Besides, the operation principle is discussed. Synchronous digital phase lock scheme is designed. Experiment with the digital control is performed, and the experimental results indicate that the proposed method has advantages of high-accuracy current control and unity power factor operation, which makes it a useful solution in practical applications.