Study on a Super Capacitor Energy Storage system for improving the operating stability of Distributed Generation system

A super capacitor energy storage (SCES) can be used as energy storage element of DG (distributed generation) system and provides necessary energy buffering. And it plays a very important role in improving operating stability of power system. Based on a wide voltage change scope of the SCES system, its main circuit has been designed in this paper, where bi-directional DC-AC-DC converter is regarded as transition circuit. The working situations of the SCES system under different loads have been analyzed in detail, and the corresponding system unified model is established when super capacitor is charged or discharged. According to the operating mechanics of SCES system, the relation between the stability of DG system and SCES system has been analyzed, and a better control scheme has also been designed. At last, the investigation of the SCES system and its control strategy are done with the use of exact simulation model. The simulation results verify the validity of designed scheme and the flexibility of control system.