Abstract:Generally single phase grid connected photovoltaic inverter adopts double closed loop control and utility voltage feed forward control strategy, in which the out voltage loop of double closed loop adopts PI constant voltage to control the before inverting DC voltage. In this paper, the output external characteristics of the two current inners of quasi proportion adjustment and PI adjustment were compared, the model of inner current was established, and the single phase grid simulation model of the inverter was set up. Simulation results show that the inner current using the quasi proportion and resonant control can be realized without static error of current control, and reduce the influence of power grid frequency deviation on grid current. Good sinusoidal current waveform is obtained. The photovoltaic inverter based on the parallel control strategy can realize electricity generation with high power factor, fast dynamic response, strong robustness and high tracking precision. Grid current THD is obviously better than traditional method, thus proving the feasibility and practicability of this scheme.
