Robust Frequency Control of Microgrid Containing Electric Vehicles

With the increase of renewable energy resources (RESs) and electric vehicles (EVs) integrated into microgrid (MG), frequency instability caused by disturbances and uncertainties will affect the stable operation of MG. Existing studies of frequency control mainly focus on the design of an appropriate controller. However, due to low inertia caused by the lack of traditional generation and unpredictable load fluctuation brought by EVs, the requirements on frequency controller need to improve. To deal with this challenge, an H∞ robust controller is designed to stabilize MG frequency in this paper. By controlling the output power of micro-turbine (MT), proposed controller balances the difference between active power and load. Three cases which include the fluctuation of RESs output power, the variation of user load and the process of EVs connected to MG are considered to verify the performance on proposed controller. The comparison between H∞ robust controller and classical proportional-integral (PI) controller is also presented. Simulation results validate that the designed H∞ robust controller provides reliable frequency support successfully to an islanded MG under the disturbances of RESs and EVs.