PQ-Coupling Strategy for Droop Control in Grid-Connected Capacitive-Coupled Inverter

Droop control has been a well-known technique for power-sharing control of the grid-connected inverters. However, droop control with special strategy is required for capacitive-coupled inverters (CCIs) since the large coupling capacitance in CCI and decoupled nature in droop control massively narrow the controllable power range of droop control and makes the application impractical. So far, less work is done on the topic, and in this paper, the phenomenon of narrowed controllable power range in droop control is investigated, and a solution is proposed by introducing a novel active-reactive power (PQ)-coupling strategy. The proposed control is being tested on a laboratory CCI prototype. The simulation results and experimental verifications are presented to show the feasibility and validity of the proposed coupling droop control strategy.