| In recent years, the rapid development of global economy makes the power demand of whole society also grow rapidly. On one hand, the large power grid which is in the way of central generation and long distance transmission is gradually becoming mature, on the other hand, it is a new development direction to connect the microgrids with large power grid which form the flexible power supply power system. As one of the core parts of microgrids, storage technology plays an important part in the improvement of microgrids’ operational characteristics and reliability of power supply, and storage energy facilities are operating perfect with new energy power generations.This paper firstly studies the standard models and key control techniques of microgrids, and analyzes several main DGs in detail, including working principles, system structures, mathematical models, control strategies and so on. And then the battery energy storage and superconducting magnetic energy storage charge-discharge principles and control strategies are discussed, and further more build the simulation models in PSCAD/EMTDC to analyze dynamic characteristics. A combination of those two energy storage models is built based on the different characteristics, and realize the unity of control. It also builds a microgrid with the combination of storages in the software. The study is focused on the operational characteristics of microgrid and energy storages during the process of connected operation to isolated operation and again to the connected operation. And also it studies the situation when a three-phase short circuit occurred to the microgrid bus. The results show that the composite energy storage has both the two energy storage advantages, it can response rapidly, balance the power flow, stable voltage fluctuation and meet the load demand of power supply. It ensures the stable operation of microgrid. |
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