Research on grid-connected inverter based on virtual grid voltage flux and PLL without grid voltage sensors

In order to improve reliability and resist interfere when grid voltage occurs fluctuation and distortion, and further reduce the cost for the grid-connected inverter, the control strategy is presented based on phase lock loop (PLL) and virtual grid flux without grid voltage sensors. The virtual grid flux vector orientation, d-axis current and q-axis current close-loop control are used based on the mathematic model in synchronous rotating reference frame for the grid-connected inverter, which achieves the decoupling control for d-axis current and q-axis current. The active power and the reactive power are independently controlled by q-axis current and d-axis current. Simulated and experimental results show that the grid-connected inverter based on PLL and virtual grid flux has a good dynamic and static performance. So the feasibility and correctness for the control strategy is verified.