New approach for sizing of overloaded-capable battery for Microgrid frequency control using cooperation of PVs, BESS and smart lighting loads

The frequency control of an islanded microgrid is consisted of primary frequency control (PFC) and secondary frequency control (SFC). This paper proposes a novel cooperative application of Battery Energy Storage System (BESS), Photovoltaic (PV) systems and LED lighting loads (LEDLLs) to quickly intercept frequency deviation in the stage of PFC. The slow responding distributed generators handle SFC by restoring the frequency to its nominal value. For participation in PFC, in the case of power shortage, LEDLLs decrease their power consumption, and in the case of power surplus, the PVs decrease their power generation. While PVs and LEDLLs are participating in PFC with their maximum capability, the BESS frequency controller is tuned to inject/absorb enough power in both cases to keep the frequency within safe limits. In this paper for battery sizing, instead of using its nominal power, a modified overloading capability to fast discharge/charge is used to reduce the required battery size for PFC that also prevents damaging it during fast discharge/charge for PFC. The proposed approach is evaluated on the CIGRE low voltage microgrid using MATLAB/Simulink software. Simulation results show that besides the overloading characteristics, the cooperative utilization of BESS, PVs and LEDLLs also reduce the battery size.