Development energy management strategy of SMES-based Microgrid for stable islanding transition

摘要

Seamless switching between grid-connected mode and islanding mode is important to Microgrid stable operation. The grid can be disconnected from the utility during large events (i.e., faults, voltage collapses, etc.). As a result, these events may affect the stable operation of Microgrid. This paper presents a control strategy to mitigate the frequency and voltage fluctuations during the islanding transition of Microgrids. The strategy depends on managing the energy stored of a superconducting magnetic energy storage (SMES). The studied Microgrid is a 33-bus system supplied by utility at normal operation. During the islanding transition, the Microgrid is supplied by two diesel synchronous generators. Wind energy conversion system of squirrel cage induction generator type is connected to the Microgrid with high penetration level of 30% at constant wind speed. SMES unit consists of superconducting coil, cryogenic refrigerator, step down transformer, power conditioning system, cryostat/vacuum vessel, and DC-DC chopper. The procedure of control is based on fuzzy logic controller. The results obtained show the effectiveness of the control strategy of SMES energy in seamless switching between grid-connected mode and islanding mode and mitigating the frequency and voltage fluctuations under switching states.