Comparison of the Performance Between Stationary Frame and Synchronous Rotating Frame Control of Single-phase Grid-Connected Inverter With LCL

Control strategy of a single-phase grid-connected inverter with LCL filter has been a mature research topic. But the most widely-used control method is stationary frame PI (SFPI) current control, which is unable to achieve a unit power factor (PF) and zero steady-state error (SSE) output current. In order to overcome this problem, the synchronous rotating frame PI (SRFPI) control which is widely used in three-phase inverter is applied to the single-phase inverter. This paper first sets up a mathematical model of a SFPI controlled inverter and finds out the relationship between the controller parameters and the inverter output PF and SSE. Then the paper figures out that the output PF and SSE of inverters controlled by SFPI have a maximum value. As comparison, the model of inverter controlled by SEFPI is set up, and a simplified transfer function of the double-inputs double-outputs system of the controller term is obtained to tune the control parameters. Then, the expression of the output PF is derived and proved to be 1 independently of the controller parameters. Finally, simulation and experiment is used to verify the analysis.