Research On The Inciprocal Effect Between Electric Vehicles And Power Systems Considering Frequency Regulation Process

With the modification of electrical industry and market structure and the booming development of renewable energy,a more effective method of frequency regulation is demanded.Meanwhile,due to the development of electric vehicles and its energy storage characteristics,there is a trend towards the integration of electric vehicles into grid frequency regulation process.Supercapacitors and batteries,as two different types of electric vehicle energy sources,have a faster response speed than conventional units.They can both participate in the auxiliary services such as grid frequency regulation.However,since supercapacitors have low energy density,and the loss of battery cycle life is rather serve when they are frequently charged and discharged,supercapcitors and batteries both have their own limitations.Therefore,based on the analysis of the impact of electric vehicles participating in grid frequency regulation on both sides of power grids and electric vehicles,a reasonable grid frequency regulation strategy should be formulated so that the advantages of different kinds of electric vehicle energy sources will be fully utilized to realize a win-win relationship between grid and electric vehicles.Firstly,the working principles of supercapacitor and battery are analyzed.Considering the driving requirements of electric vehicles,the series-parallel relationship between supercapacitors and battery cells are analyzed.Electric vehicle energy source model for grid frequency regulation analysis is established.A single-area power system model is established based on the principle s of grid frequency regulation.Secondly,the multi-time-scale fluctuation characteristics of wind power are analyzed.Wind power is decomposed by empirical mode decomposition method and then reconstructed into different time scales.The ability of supercapacitor and battery energy sources to absorb wind power at different time scales is analyzed.The depreciation coefficients of supercapacitor and battery energy sources are calculated.Thirdly,the process of electric vehicle participating in grid frequency regulation is analyzed,which verifies the feasibility and superiority of the participation of electric vehicle.By analyzing the dynamic response character istics of the battery and supercapacitor,different strategies for grid frequency regulation are developed.By calculating the depreciation coefficient of energy sources in the process,the grid is instructed to economically compensate electric vehicle users.Meanwhile,the effect of energy sources on grid frequency stability is analyzed under different working conditions and different control strategies.The effect of energy sources on the grid frequency stability under large disturbances is compared and analyzed under droop and virtual inertia control.