| With the rapid development of the economy,the scarcity of traditional fossil energy sources has become increasingly severe.At the same time,with the proposal of the Beautiful China Strategy,electric vehicles have become a choice for people to travel.With low energy consumption and being environmentally friendly,electric vehicles have been rapidly developed because of the continuous development of battery technology and the support of national policies.The charging and discharging behavior of large-scale electric vehicles in the future will bring huge challenges to the reliability of grid operation.To predict the charging and discharging daily load of electric vehicles under different charging and discharging modes,and study its impact on grid operation is urgent for grid companies to regulate the charging and discharging load of electric vehicles,reduce the peak-to-valley difference,increase the utilization rate of power equipment,and ensure the reliability and safety of grid operation.The research of the thesis is generated in this context.This thesis uses a combination of qualitative and quantitative methods to conduct research in accordance with the technical route of problem-analysis-solution.The main work includes:First,the paper analyzes the research literatures on the forecast of charging and discharging daily load of electric vehicles,defines the scientific issues studied in the paper,and selects the charging and discharging behavior of electric private cars and electric buses that have a large impact on the grid load as a research sample.By the method of combining literature research and actual research,the paper extracts six main influencing factors of electric vehicles’ charging and discharging load,namely the charging method,the start time of charging and discharging,the daily driving mileage,the battery characteristics,the number of electric vehicles and the type of electric vehicles,and explains each factor.Second,the paper analyzes the charging and discharging behavior of electric private cars and electric buses under different charging and discharging modes,and builds load calculation model of electric private cars and electric buses in disorderly charging,one-way ordered charging and two-way ordered charging and discharging modes.Taking the charging and discharging behavior of two types of electric vehicles in Tianjin as an example,using Monte Carlo method to predict the daily load of electric vehicles in Tianjin under three charging and discharging modes.Third,the paper comparatively analyzes the effects of disorderly charging,one-way ordered charging and two-way ordered charging and discharging modes on the grid load.The research results show: under disordered charging mode,the peak of electric vehicle charging load appears at 18: 00 p.m.-22: 00 p.m.,this period coincides with the peak time of the power grid,causing the adverse consequences of "peak plus peak";under one-way ordered charging mode,the charging load of electric vehicles transfers from the peak time at night to the valley period affected by peak-valley price,playing a role of "shifting peaks and filling valleys",but during10:00 a.m.-12:00p.m,the "peak plus peak" phenomenon still exists;under the two-way ordered charging and discharging mode,electric vehicles discharge during the peak time of the power grid and charge during the valley time of the grid,which can not only reduce the load between 10:00a.m.-12:00p.m.and 18: 00 p.m.-22:00 p.m.,but also improve the power consumption during the valley period,and simultaneously provides reserve capacity for the power grid to ensure the stability of the power grid operation.Fourth,based on the above research results,the paper proposes countermeasures and suggestions for grid companies to participate in electric vehicles load regulation and their large-scale development under three charging and discharging modes.Under the disorderly charging mode,grid companies should rationally plan the construction of charging infrastructure,reduce input costs,and actively carry out research on orderly charging and discharging strategies to promote the development of orderly charging and discharging modes.Under the one-way orderly charging mode,grid companies should promote the application of intelligent orderly charging facilities,improve charging methods,and optimize the peak-to-valley price to increase user incentives.Under the two-way orderly charging and discharging mode,grid companies should promote the construction of integrated charging-discharging facilities,improve charging-discharging services,and rationally arrange charging and discharging plans,optimize charging and discharging power. |
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