Active power — Voltage control scheme for islanding operation of inverter-interfaced microgrids

Efficient and effective use of renewable energy, distributed generation and energy storage can potentially solve global problems such as energy crisis and climate change. A promising solution to interconnecting these distributed energy resources with the grid is the microgrid paradigm. A microgrid may comprise a variety of inverter-interfaced distributed energy resources such as photovoltaic arrays, wind turbines, fuel cells, microturbines, energy storage devices (such as batteries, super-capacitors) and controllable loads. The microgrid paradigm provides considerable control flexibility: it can be connected with the utility grid, or it can operate isolated from the main grid in case of disturbances or faults. A key issue is how to control the parallel inverters in islanding operation so as to achieve high performance of power and voltage regulations in the microgrid. This paper presents a new active power and voltage control scheme for inverters and a droop control method for the power sharing among the parallel inverter-interfaced distributed energy resources. The proposed control method is tested in two scenarios: (1) a single inverter operated in the islanding mode, (2) two parallel inverters operated in the islanding mode. Simulation results suggest that this control method can control the active power and voltage magnitude of the single inverter very well and regulate the parallel-connected inverters as well.