Performance Evaluation of BESS Moving Average Control for 1MW PV Plant

The development of the grid-connected photovoltaic (PV) system is growing rapidly since 1993 as it is considered as the renewable energy which used to replace fossil fuels. However, the output of the PV system can fluctuate significantly due to the movement of clouds. In this paper, a 1MW PV system is modelled and the smoothing performance of BESS system with moving average method is studied. A total of four different types of solar weather including overcast, clear sky, high variability and low variability are used to study on the smoothing performance and BESS sizing. BESS plays a vital role in smoothing application as it will charge and discharge when there is a power fluctuation. A proposed method is used to determine the BESS capacity and its initial state of charge by analysing the relationship between ramp-rate, battery capacity and moving average control window size. It is found that the window size of 10 minutes can achieve ramp-rate under 10%/min for all weather conditions, at the same time having a lower battery capacity as compared to other window sizes. The proposed method suggests 90kWh of battery capacity is suitable for a 1MW PV plant. The proposed BESS battery sizing method shows that the BESS capacity for PV moving average smoothing application is about 10% of the PV plant capacity.