| This thesis was supported by National Natural Science Foundation of China(51277184) and independent research project of State Key Laboratory of PowerTransmission Equipment&System Security and New Technology(2007DA10512709209).With the increasing penetration of EVs, a large scale of charging load access willseriously affect power quality, equipment utilization, network’s loss, as a typicalharmonic source, it will adversely affect other loads, generators and monitoring andmeasuring devices. In order to mitigate the impact of high-density rechargeable load tothe distribution network, energy storage device or mobile storage device should beconfigured to meet with the requirements of the grid active power ramp rate in thecharging station. Meanwhile, it also need comprehensive monitor the operation status ofEVs, charging facilities and other equipment. Therefore, the research on energy storagebuffer system operation mode and its control strategy and monitoring and evaluation ofEVs and charging facilities are important. The main contents are as follows:○1Using the energy storage buffer system to compensate the pulse power of fastcharging electric vehicles, the operation mode and its current control strategy of energystorage buffer system are proposed, which takes into active rate limits of the distributionnetwork into account. Combining fast charging station structure and charging powercharacteristics of different types of batteries, different operation mode of charging anddischarging process for energy storage buffer system are analyzed; then the energystorage buffer system operation parameters are deduced according to the chargingstation storage configuration requirements and further more design the energy storagesystem component parameters. Using Matlab/Simulink software, we build a model offast charging station with energy storage buffer system, analyze the dynamiccharacteristics of fast charging station with different pulse charging power, and verifythe correctness and effectiveness of the control strategy.○2Based on state index of EV key components, EV state comprehensive evaluationindex system is established. First, the state indexes are chosen according to the EV keycomponents; and then introducing the calculation method of the indexes, classifying theindexes by their correlation, and excluding the indexes with little contribution rate;finally conducting a comprehensive assessment for EV and its key components based on its comprehensive evaluation index system.○3An online monitoring, analysis, and evaluation system of electric vehicle (EV) chargingstation is designed and developed. The hardware and software architecture of the system aredesigned in detail according to its functional requirements; Based on the monitoringdata, the system can analyze the operation characteristics of distribution transformer andchargers, and statistics the probability of start charging time, initial of charging state anddaily mileage. The monitoring data shows that the current harmonics are larger whenEV charging and gradually become smaller as charging power increasing, and it alsoshows that the battery performance decline because of rapid charging and discharging. |
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