Power Control of Hybrid Grid-Connected Inverter to Improve Power Quality

Hybrid grid-connected inverter (GCI), also called reconfigurable GCI or shunt-series-switched GCI, can be connected in shunt or series to the grid to improve power quality of the grid. Power control capability of GCI is a key element to apply the concept of hybrid GCI to different kinds of distributed energy resources. Different power control strategies including zero power injection, minimum apparent power injection, and zero oscillating power injection are presented in shunt and series mode of hybrid GCI by adjusting reference voltage. Mathematically derived equations of the optimal phase angle are presented for different strategies. Experimental results of 10kW of hybrid GCI prototype are also presented that hybrid GCI compensates 15% of voltage swell in series mode when zero reactive power injection strategy is applied.