Active power management of a super capacitor-battery hybrid energy storage system for standalone operation of DFIG based wind turbines

This paper presents an energy management strategy for a hybrid energy storage system for a wind dominated remote area power supply (RAPS) system consisting of a doubly-fed induction generator (DFIG), a battery storage system, a super-capacitor, a dump load and main loads. Operation of a battery storage system is coordinated with a supercapacitor with a view to improve the life span of the battery. In this regard, the battery storage system is connected to the load side of the system while the supercapacitor is connected to DC bus of the back-to-back converter of the DFIG. The operation of the hybrid energy storage system is coordinated through the implementation of an energy management algorithm (EMA) which is developed with a view to reduce the depth of discharge (DOD) and ripple content of the battery current. The dump load is connected to the load side of the system which utilises the power in situations that can not be handled via energy storage system. In addition, a novel coordination method has been proposed to coordinate the power flows among all system components with a view to regulate the power flow and thereby ensuring the robust voltage and frequency control on the load side and capturing the maximum power from wind.