Charging/discharging Strategies Of Electric Vehicles And The Synergistic Complementary Operation With Renewable Energy In A Micro-grid

With rapid economic development,energy consumption continues to grow and environment pollution becomes increasing heavy.Replacement of internal combustion engine vehicles by electric vehicles,can motivate utilization of clean energy espically renewable energy and reduce carbon emissions in transportation.However,the continuuous growth of the EV fleet creates enormous pressure on the security and stability of the power grid.In the meantime,large-.scale grid-connection of renewable energy,such as wind power and photovoltaic(PV),also endangers the power grid and this has led to a significant amount of electricity being discarded.Therefore,the thesis aims to study how EVs,via vehicle-to-grid(V2G)technology,could assist in the operation of microgrids,meanwhile improve the utilization rate of renewable energy.The specific objectives include:(1)the spatial-temporal distribution of EVs charging/discharging and the impacts on the power grid;(2)the influences of different pricing mechanisms on the charging/discharging of EVs;(3)the spatical-temporal distribution of V2G capacity;and(4)integrated optimization of EVs charging/discharging and utilization of renewable energy in a microgrid.To the objective regarding the EVs charging/discharging behavior and the impacts on the power grid,this thesis established an EV travel model based on the NHTS database,and proposed a model to predict the charging/discharging behavior of EVs.The thesis analyzed the spatial-temporal distribution of EVs' charging/discharging behavior in a resdential area.The influences of EVs' charging on the power grid at different peneration rates were also studied.To the objective regarding the influences of different pricing mechanisms,this thesis studied the demand responses under different pricing mechanisms,namely peak-to-valley,time-of-use and real-time price.On the basis,the charging/discharging patterns under different pricing mechanisms and the effects on the power supply side and user side were examined.To the objective regarding the spatial-temporal distribution of V2G capacity,the thesis established a model to predict the spatial-temporal distribution of V2G capacity based on the information on EVs'parking and charging/discharging.This thesis then empolyed the model to study the remaining capacity of EV batteries,V2G capacity and V2G potential.The influences of the volume of EV and battery size were also evaluated.To the objective regarding integrated optimization of EVs charging/discharging and utilization of renewable energy,this thesis established an optimization model on the operation of an entire microgrid,where intermittent renewable energy,i.e.PV cells,was included.A particle swarm optimization algorithm with variable inertia weight was employed to solve the optimization problem.The results on the operation of the microgrid were obtained to achieve the lowest operation cost.