Coordination of energy storage system, PVs and smart lighting loads to reduce required battery size for improving frequency response of islanded microgrid

Abstract

The frequency control of an islanded microgrid (MG) consists of primary frequency control (PFC) and secondary frequency control (SFC). This study proposes to use the Battery Energy Storage System (BESS), the Photovoltaic (PV) systems and the LED lighting loads (LEDLLs) to quickly intercept the frequency deviation in a coordinated manner in the PFC stage. The PVs decrease their power generation in the case of surplus power generation. The LEDLLs are interfaced with power electronic devices, which realize the adjustment of the LEDLLs luminance at the desired level. The LEDLLs are controlled to decrease (increase) their power consumption in the case of power shortage (surplus) by lowering (rising) their luminance level. A participation factor is considered to use those LEDLLs for PFC with the consumers’ consent to participate in PFC. While the PVs and LEDLLs are participating in the 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. Some batteries are capable of overloading or fast discharging/charging. In this paper, for battery sizing, instead of using its nominal power, a modified overloading characteristics is used, which considerably reduces the required battery size for PFC, and also prevents damaging it during fast discharging/charging. The MG under study is the CIGRE low voltage network, which is used for evaluating the proposed approach. The simulation results show that both the overloading characteristics and the cooperative utilization of the BESS, PVs and LEDLLs reduce the required battery size.