Control Strategies for the PV-Integrated Islanded Microgrid Under Normal and Fault Conditions

This paper describes the corresponding control strategies for the normal and fault operation states of the islanded microgrid system. The islanded microgrid system consists of distributed energy resources (DER) such as photovoltaic (PV), hybrid energy storage (HES) and microturbine (MT) and loads such as pumping unit load (PUL) and equivalent load. In the normal condition, it adopts a voltage and frequency (V-f) control strategy for the inverter of MT to maintain constant voltage and frequency of the whole system and a constant power control strategy for the rest of the power inverters. In the fault condition, the front and rear stages of the PV system adopt constant power control and reactive power compensation priority control respectively, thus realizing low voltage ride-through (LVRT). The proposed control strategies can ensure the stability of voltage and frequency of the microgrid during normal conditions and the ability of the PV system to achieve LVRT during fault conditions. A simulation model of the islanded microgrid system based on PSCAD/EMTDC is constructed and the effectiveness of the control strategies under normal and fault conditions is verified.