Based on the concept of cyber physical system (CPS), a novel hierarchical control strategy for islanded microgrids is proposed in this paper. The control structure consists of physical and cyber layers. It’s used to improve the control effect on the output voltages and frequency by droop control of distributed energy resources (DERs), share the reactive power among DERs more reasonably and solve the problem of circumfluence in microgrids. The specific designs are as follows: to improve the control effect on voltages and frequency of DERs, an event-trigger mechanism is designed in the physical layer. When the trigger conditions in the mechanism aren’t met, only the droop control (i.e., primary control) is used in the controlled system. Otherwise, a virtual leader-following consensus control method is used in the cyber layer to accomplish the secondary control on DERs; to share the reactive power reasonably, a method of double virtual impedance is designed in the physical layer to adjust the output reactive power of DERs; to suppress circumfluence, a method combined with consensus control without leader and sliding mode control (SMC) is used in the cyber layer. Finally, the effectiveness of the proposed hierarchical control strategy is confirmed by simulation results.

Abstract-The access of distributed generation is one of the important functions for future energy management system. In this paper, technologies with information interaction of devices and energy management system for distributed generation "plug and play" access was analyzed. A "plug and play" control model and its application energy management system were introduced. The proposed system could meet power system connection requirements and operation limitations by guaranteeing the output characteristic of distributed generation. It will provide a reference for future corresponding study.

The "plug and play" and effective deployment of distributed generation accessible is important in further smart grid, which related to the security and stability of power system operation. A multi-agent system (MAS) based micro-grid control framework was proposed in the paper. The "plug and play" model based on MAS and power electronic technology were developed firstly, and the coordinating control strategy of microgrid was analysed. Finally some simulation studies obtained and a thought of the distributed generation "Plug and Play" in microgrid provided.