Study Of Distribution System Planning Considering Electric Vehicle Charging Facilities

At present,with the advantages of low carbon,energy saving and high efficiency,electric vehicles(EV)have attracted wide attention in the world.The commercialization and industrialization of EV must rely on the construction of charging facilities.EV charging facilities are not only supporting device for urban traffic,but also important new power loads which have brought new challenges to the operation and control of distribution systems.In order to effectively promote the healthy and rapid development of EV industry and urban distribution systems,it is necessary to incorporate EV charging facilities into the distribution system planning,and establish a mechanism for coordinated planning and common development,which needs to take into account the travel demand and convenience of EV users as well as the current status and future developing trend of distribution systems.Therefore,taking the EV battery-swapping station and the EV charging station as the breakthrough point respectively,study of distribution system planning considering electric vehicle charging facilities from the perspective of reality and from the perspective of future are both conducted.The charging operation of the EV battery-swapping stations has a high degree of schedulability,which gives it the characteristics of energy storage that can stabilize the fluctuation of distributed generations in the distribution systems.Therefore,from the perspective of reality,a multi-scenario coordinated planning method for the distribution system taking into account both the EV battery-swapping stations and the distributed generations is proposed.Firstly,the seasonal multi-scenario model of distributed generations is constructed by using the method of synchronous back substitution.Then,under the multi-scenario model,the coordinated charging strategy of the EV battering-swapping station is determined based on the principle of minimum net load fluctuation.Also,a spare battery scheduling scheme and a calculation method of minimum battery number are introduced in the text,on the premise of the constraints of battery-swapping demands and constraints of battery existence are both satisfied.Finally,a multi-scenario coordinated planning model of EV battery-swapping stations and distributed generations based on coordinated charging strategies is constructed,where the minimum sum of construction costs,operation costs,integrated load fluctuation costs and network loss costs is taken as the objective function.Simulation analysis is taken on the IEEE 33-bus distribution system by the biogeography-based optimization method.Results show that the proposed minimum battery calculation method can make full use of the daily battery recycling in the battery-swapping stations,thus substantially reducing the investment cost of the battery-swapping stations on the premise of maintaining the coordinated charging.And the proposed planning method can achieve peak load shifting by introducing the coordinated charging strategy in battery-swapping stations.Thus,the network losses will be significantly reduced,and the planning capacity of distributed generations in distribution network will be greatly improved.It has a guiding role for the planning of distribution networks with EV battery-swapping stations and distributed generations.The charging demands of EV quick charging stations are always flowing in the traffic network,which makes it an important link between the power network and traffic network in the integrated energy distribution system comprising electricity,natural gas,heat and electrified traffic.Therefore,from the perspective of future,a planning method of the integrated energy distribution system considering the EV charging stations is proposed.Firstly,the energy hub model is applied to characterize the terminal integrated energy unit which includes EV charging station,combined heat and power plant,power to gas plant and other energy conversion devices.Then faced with the supply-side reform,a multi-energy supply conversion response strategy is put forward.Accordingly,by taking full account of the economic performance of system construction and operation and the space-time charging satisfaction of EV users,a comprehensive planning model for the integrated energy distribution system is proposed,where the system construction and operation cost,the charging time utility function for slow charging stations and the traffic flow utility function for quick charging stations are all calculated in the objective function.And simulation analysis is taken on an integrated energy distribution system which is composed of the IEEE 14-node distribution network,the 20-node natural gas network and the 25-node traffic network.Results show that two utility functions for charging stations can be used to guarantee satisfaction of charging time and convenience of charging site respectively.And by adjusting the energy structure and the conversion mode,the proposed supply conversion response strategy can reduce energy costs and optimize operating characteristics without changing load demands.Also,based on the transverse complementation and longitudinal coordination among the power network,the natural gas network and the traffic network,the introduced planning pattern based on terminal integrated energy unit can realize coordinated planning of multiple forms of energy and contribute to higher comprehensive benefit of system construction and operation.