An Improved Decentralized Control of Grid-Connected Cascaded Inverters with Different Power Capacities

The existing decentralized control for modular cascaded inverters is based on the assumption that all inverter modules have same capacities. However, available source power capacities of cascaded inverters may be different in practical distributed generation systems. To address this issue, this letter proposes an improved decentralized control scheme, in which the voltage amplitudes vary according to their individual available powers. Moreover, a power factor consistency control is proposed to achieve autonomous voltage phase synchronization. The steady-state analysis and synchronization mechanism of cascaded inverters are illustrated. In addition, the proposed strategy offers other advantages, including adjustable grid power factor and immunity to grid voltage faults. The effectiveness of the proposed control is tested by experiments.