Novel capacity configuration method of hybrid energy storage system to smooth output power fluctuation of photovoltaic power plant

Abstract

Due to that rise of clean energy in recent year, Chinese photovoltaic (PV) power generation has been greatly increased. However, photovoltaic power generation has intermittency, variability and uncertainty, so its output power needs to be suppressed. It can adopt a hybrid energy storage system composed of power energy storage and capacity energy storage to stabilize the fluctuation of photovoltaic electric field output power. Firstly, the array element model of 1MW/250kWh flywheel and the array element model of 250 kW/150 kWh lithium ion battery are established. Secondly, the energy storage system command decomposition method is proposed through the modified wavelet packet decomposition method. By decomposing the power given by photovoltaic electric field, the respective target instructions of hybrid energy storage system are obtained.From the boundary time of charging and discharging responses of flywheel and lithium ion battery energy storage array, the respective target instructions of each energy storage array are obtained. Then, considering the charging and discharging efficiency of each energy storage array and the state of charge, the capacity configuration method of hybrid energy storage system is proposed. Finally, According to the output data of a photovoltaic field with a rated installed capacity of 25 MW, the proposed HESS capacity allocation method and stabilization effect are simulated and verified.