基于混合公共连接单元的柔性互联多微网结构与控制方法

Multiple microgrids are the structure extension and function expansion of single microgrid, which is one of the important ways to absorb high-permeability renewable energies. In order to solve the problems of huge disturbance influence and poor control flexibility of the AC interconnected multiple microgrids, this paper proposed a hybrid unit of common coupling for multiple microgrids. The interface consists of AC/DC switches, a voltage source converter and energy storage devices. The study designs the structure, the connection mode and the control mode of the hybrid unit, and constructs the flexible interconnection scheme for multiple microgrids. The gird-connected mode, islanding mode, and emergency mode as well as the mode switch method were then proposed based on the hybrid units of common coupling. The tri-layer coordinated control architecture of central layer, interface layer, and microgrid layer and its control method were also presented. The simulation model of the multiple microgrids based on the hybrid unit of common coupling was built in PSCAD/EMTDC. The simulation shows that the proposed architecture and control method has good steady-state and transient operation performance. Meanwhile, the actual operation results under different modes prove better than the operation requirements. The multiple microgrids based on the hybrid unit of common coupling is a feasible method to organize and coordinate the operation of high-permeability distributed generation. It is suitable for the multiple microgrids that requires high stability and flexibility.