Research on the Z-source inverter grid-connected control of micro-grid based on differential geometry

Aiming at the Z-source inverter used in the micro-grid and its grid-connected control research, the photovoltaic system was taken as the example. The inverter integrated three functions including MPPT (Maximum Power Point Tracking), step-up/down DC-side voltage and output grid-connected. In order to overcome the system instability caused by zero point of Z-source net in the right half-plane, the paper proposed nonlinear control method based on differential geometry theoretic, which overcomes the non-minimum phase behavior. When the input condition of the photovoltaic system changes, this control method could make the Z-source inverter DC side output track the MPP rapidly, steadily and little overshoot, and the inverting side output three-phase voltage transmit rapidly and steadily, then improved the quality of grid-connected current. The simulation contrast and experiment result proved the proposed method in the paper is correct and effective.