Design of Proportional-Integral Controller of Hybrid Grid-Connected Inverter for Active Power Injection and Unbalanced Non-Active Power Compensation

With the characteristics of a low dc-link operating voltage of the active inverter part and thyristor controlled passive part, the hybrid-coupling grid-connected inverter (HGCI) can reduce the system and operational costs as well as extend the operational range compared with the conventional inductive-coupling grid-connected inverter (IGCI) and capacitive-coupling grid-connected inverter (CGCI) for the renewable energy generation. In this paper, a control strategy by using proportional-integral (PI) controller of the HGCI for active power injection and unbalanced non-active power compensation will be proposed and presented, which can reduce the switching current ripple and obtain better active and non-active power compensation compared with the conventional hysteresis current controller. Finally, simulation and experimental results are provided to verify the performance of the designed PI controller for the HGCI under unbalanced loads operation.