Research On Multi-time-scale Hierarchical Optimal Scheduling Of Wind/solar/diesel Microgrids With Electric Vehicle Charging Stations

With the increasing number of new energy electric vehicles,charging electric vehicles with microgrid or microgrid group can effectively reduce the power demand of a large number of electric vehicles for large power grids.As an "energy storage" function,it can effectively reduce the energy storage allocation of microgrid with high proportion of renewable energy and promote the development of distributed photovoltaic and wind power.In this thesis,aiming at the wind/PV/diesel microgrid with electric vehicle charging stations built in industrial parks,the multi-stakeholder hierarchical optimal scheduling problem that electric vehicles participate in microgrid operation through orderly charging/discharging is mainly solved,realizing the synergy between the electric vehicle group's "orderly charging-energy support,short-time discharging-power support" for wind/PV/diesel microgrid and the two stakeholders of electric vehicle users and microgrid operators.The main work of this thesis is as follows:(1)Establish a charging/discharging pricing mechanism to guide the orderly charging and short-time discharging of electric vehicles.Firstly,the load characteristics of electric vehicle charging station are analyzed,and Monte Carlo method is used to predict the charging load.Then,the output model,cost model and translatable load penalty cost model of photovoltaic power generation,wind power generation and diesel generator sets are established.The generation cost of wind/PV/diesel microgrid under different operating conditions is analyzed,and the pricing mechanism of time-sharing charging price and short-time discharging price is established.Based on the principle of electricity price guidance,the scheduling model of orderly charging and short-time discharging of electric vehicle charging stations is established,and the lowest cost electric vehicle charging/discharging power distribution is obtained.(2)Establish a hierarchical dispatching system of wind/PV/diesel microgrid with electric vehicle charging stations.The mathematical relationship between two stakeholders,electric vehicle charging station and microgrid operator,is analyzed,and the hierarchical dispatching system of wind/PV/diesel microgrid with electric vehicle charging station is established.As the upper-level decision maker,microgrid sets the time-sharing charging price based on its operating cost,the charging station,as the lower-level subordinate,establishes an orderly charging plan according to the timesharing charging price.At the same time,considering the "energy storage" characteristics of electric vehicles,the microgrid formulates a "short-term power support" electricity price guiding mechanism to guide the electric vehicles with electricity quantity meeting the requirements to discharge and meet the power supply reliability of important loads in the microgrid.(3)Considering the accuracy of distributed generation and load forecasting,a dayahead/short-time optimal dispatching model of wind/PV/diesel microgrid with electric vehicle charging stations is established.In the optimal scheduling model,with the constraints of power output restriction and power supply-demand balance,the microgrid layer establishes a multi-objective function with the lowest operating cost,the highest utilization rate of renewable energy and the highest load satisfaction,the charging station layer establishes an objective function with the lowest charging cost.In the short-term rolling optimization,the objective function of the microgrid layer is to minimize the adjustment of the previous generation plan and the cut-off of important loads,the objective function of the charging station layer is to minimize the ordered charging adjustment plan considering the short-term generation support.The mixed integer linear programming algorithm is used to solve the generation plan of each power source in microgrid.Two typical examples of normal and abrupt weather are selected for simulation verification.The simulation results show that the proposed multi-time scale hierarchical scheduling system can realize the synergy between electric vehicle charging stations and microgrid,and ensure that the electric vehicle group can "orderly charge-energy support,short-time discharge-power support" for microgrid without energy storage.