Improved coordinated control strategy of hybrid energy storages in PV Power Smoothing

High penetration of renewable energy could causes system frequency fluctuation of power flow and this significantly affects the power system operation. Control strategy of Flywheel and lithium battery hybrid energy storage system (HESS) is designed in this paper. An improved energy allocation strategy of grid-connected PV power smoothing strategy is designed. Coordinated control strategy is added to avoid the power output direction inconsistent of two kinds of storage, and consider energy storage SOC level simultaneously. This strategy effectively reduces the number of charge and discharge cycles of energy storage system(ESS). The strategy is applied to a demonstration project. Results show that the proposed coordinated control strategy can improve the life expectancy of the battery and reduce the operating cost.