Photovoltaic grid-connected inverter based on frequency feedback PR controller

The photovoltaic (PV) grid-connected power generation has become an important direction of energy development. A grid-connected inverter is the key equipment in the PV grid-connected system. The efficiency and performance of the PV grid-connected inverter mainly depend on its topology and control technology. The PI controller has good dynamic and steady-state performance, which is widely used in the photovoltaic grid connected inverter system. This technique can be easily implemented. However, it has some shortcomings, such as steady-state error and poor capacity of anti-disturbance. In this paper, a proportional resonant (PR) control strategy is proposed to eliminate the steady state error and enhance the anti-disturbance ability. The PR controller has an infinite gain at the resonant frequency, but the gain is sharply decreased at other frequencies. Therefore, a frequency feedback method based on the PR controller is proposed, which can enhance adaptability of the frequency fluctuation. The experimental results are provided to verify effectiveness of the proposed control strategy.