Impact Of Battery Swap Station Using V2G Technology On Fault Characteristics Of Distribution System And The Corresponding Control Strategy

With the intensification of the energy crisis, promoting the improvement of electric vehicles is recognized as an important way to ensure energy security and develop low-carbon economy worldwide. Battery swap station attracts widespread attention as a centralized charging infrastructure recently, and has been one of the most competitive business and technology modes to guarantee the rapid development of electric vehicles. In addition, battery swap station has broad prospects utilizing V2G technology, but it will change the structure of distribution system when it is connected to the grid, and have an impact on the magnitude, flow and distribution of short-circuit current in the distribution system, thereby affecting the original protection and automation configuration of the distribution system. Against this background, the paper researches the impact of battery swap station using V2G technology on fault characteristics of distribution system and the corresponding control strategy.The working principle, charging and discharging characteristics, mathematical models and control strategy of bi-directional battery chargers are analyzed, and the complete simulation model of bi-directional battery charger is built in PSCAD. Furthermore, based on the discharging characteristics and control strategy of a single bi-directional battery charger, the simplified models of bi-directional battery chargers and the battery swap station, which are suitable for simulation analysis, are proposed.In terms of the impact of discharged battery swap station on the distribution system’s fault characteristics, the active power, reactive power, voltage and current of the battery swap station are simulated and analyzed when fault type and fault location vary in the simulation system. Then considering the different relative position of the battery swap station and fault location, the different capacity and operating state of the battery swap station, the impact of the battery swap station on fault characteristics of the distribution system is simulated and discussed.In order to reduce the impact of the battery swap station on feeder automation system of the distribution system, a control strategy is proposed. The strategy uses the features that the batteries have a certain degree of freedom and can be dominated, and includes two parts. One is the fault identification and coping stratege in overhead line and cable line distribution system, the other is the coordinated control strategy of all the bi-directional battery chargers. Then the impact of a battery swap station on feeder automation based on FTU and recloser-fuse is simulated and analyzed. The simulation results show that the proposed control strategy can effectively solve the problems of reclosing failure and misjudgment of fault region in feeder automation based on FTU and mis-coordination of recloser and fuse in feeder automation based on recloser-fuse.