Research On Electric Vehicle Charging Facilities Planning And Charging And Discharging Strategies

Environmental pollution,climate change,reduction of traditional energy sources and other issues that threaten sustainable development have caused international organizations and governments to take action to formulate energy-saving measures.Increasing private or corporate electric vehicle(EV)ownership and developing the renewable energy industry is a widely accepted practice in societies.At present,due to insufficient charging facilities(CFs),the penetration of EVs is not satisfactory.On the other hand,irrational planning of CFs cannot guarantee that drivers complete their long-distance trips,which is an important concern for people to choose whether to purchase EVs and the most critical barrier to hinder rapid increase in sales of EVs.After the planning of CFs is completed,the number of EVs charged will increase,and the power required for charging is a burden that cannot be ignored for power grid.When EVs are not traveling,the energy provided by photovoltaics(PV)is used to reduce the load on the grid caused by the increase in the penetration rate of EVs.The electric energy stored in the day can be provided to users at night for grid-supporting,but PV output is intermittent,and improper treatment also has a negative impact on the grid.Given these facts,this thesis studies the planning of CFs in view of the insufficient number and the unreasonable location of CFs.In addition,this paper also explores the energy storage characteristics of EVs to reduce PV fluctuations and provide support for the power grid.The main research contents of this thesis include the following two aspects: To promote the penetration of EVs,a CF planning model based on Yen’s algorithm is proposed for coupled transportation and distribution systems considering traffic congestion.This model not only considers the influence of new CFs on the power system,but also considers the impact of CF locations on traffic flow distribution and congestion level in the transportation system.Yen’s algorithm is innovatively employed to offer multiple possible choices for EVs drivers’ route-selection considering CF locations determined in traffic flow assignment model.Overall,the total cost of both distribution and transportation systems is minimized to obtain the optimal CF planning results.For the distribution system,power supply cost,energy loss and penalty cost for voltage deviation are included.For the transportation system,the main objective is to ensure EVs can reach their destinations at the lowest cost,while the travel time due to different path selections and the delay time caused by congestion can be minimized.Finally,a comprehensive case study on the integrated IEEE 30-bus and a 25-node transportation system is conducted to validate our approach.Plug-in electric vehicles(PEV)are easy to charge/discharge and are more popular with consumers than battery swapping ones.The energy storage characteristics of PEV batteries in cooperation with vehicle-to-grid(V2G)concept and associated power electronics can be used to reduce the impact of PV and assist the operation of grid.In addition to electricity reserved by PEV for daily travel,the limited remaining SOC is used for PV and grid-supporting.This paper studies a control strategy for PEV batteries to mitigate PV impacts and support grid.Based on the characteristics of PV,load demand and limited battery capacity,it controls the battery’s charging/discharging pattern,while ensuring PEV travel requirements and voltage stabilization.In addition,when PEV charging may be subject to passing clouds,the control of charging/discharging in this article is dynamic and varies according to the actual PV output.Finally,the control strategy of the PEV battery was tested by actual PV and load demand data.