Multi-port topology for composite energy storage and its control strategy in micro-grid

Energy storage system (ESS) plays a significant role in micro-grid, but single energy storage can´t meet the comprehensive requirements of micro-grid applications. Due to technical and economic reasons, composite energy storage is a better choice nowadays, which can combine all the suitable energy storages together, take the best of their positives to meet customer´s demand. So the topology for composite energy storage is very important. Typical topology can be used for composite energy storage is compared, upon which, a novel multi-port port based on DC-link interfacing and magnetic coupling method is proposed for composite energy storage application. The multi-port topology allows different kinds of energy storage and/or micro-sources to get in, where energy can be controlled to flow bi-directionally, in and out of energy storage. And a novel Economical inverter based on three phase four switch topology is introduced for micro-grid interface of composite energy storage, which have features of low cost, easy to control and suitable for energy storage application. A double layer control strategy is designed for composite energy storage, the upper layer is responsible for energy management, and a knowledge based energy management method is utilized to separate different energy storage. In the lower layer, a phase shift PWM method is utilized to control energy flow between different ports. Simulation experiments testified their feasibility