Parallel operation of inverters for distributed photovoltaic power supply system

This paper proposes a control technique for operating two or more single phase inverter modules in parallel with no auxiliary interconnections. In the proposed parallel inverter system, all of the modules have the same circuit configuration, and each module includes an inner current loop and an outer voltage loop controls. With power sharing control, load sharing can be automatically achieved and the output current of each inverter can be accurately limited to its maximum rating. This technique uses frequency and fundamental voltage droop to allow all independent inverters to share the load in proportion to their capacities. From the simulation and experiment results, the proposed control for PVS inverters is verified.