The impact of the time delay on the load frequency control system in microgrid with plug-in-electric vehicles

Our power system is evolving in the form of small entities called Microgrids. In this scenario, different renewable and conventional energy sources are integrated together to form the Microgrid and to satisfy a specific load. The frequency is an indication of the balance between the generation and the demand. In the conventional power system, the generators are used to balance the frequency. The emerging new technologies such as the Plug-in-Electric vehicles can play a great role in the stability of the load frequency control system. In this paper, the stability of a Microgrid with plug-in-electric vehicles and communication delay is investigated. The Microgrid controller communicates wirelessly with the plug-in electric vehicle and they form a kind of time delay system. A Microgrid model with plug-in electric vehicles and communication delay is presented in this paper. Lyapunov-Krasovskii functional is used to derive stability criterion in form of Linear Matrix Inequalities. Through solving the Linear Matrix Inequalities the maximum time delay that guarantees the stability of the Microgrid is determined. The parameters that affecting the stability and the maximum allowable delay are determined which are; the PI controller gains, the Microgrid inertia, the PEV gain and the PEV time constant.