基于动态概率模型的V2G运行模式下城市电网灾变机理与抗灾变能力研究

The power flow in the ubran grid varies with some randomicity especially Electric Vehicle is integrated.It may cause the disaster mechanism of the urban power system to become more intricacy and the security threats possibility will be higher. Thus, the research on disaster mechanism and disaster resistance capability of urban power system is very important under the condition of large-scale vehicle to grid. The dynamic random variables will be brought into the research based on the variation pattern and random volatility of the electric vehicle charging and discharging and electric load. The dynamic probability model of electric vehicle charging load and random load is described according to the composition of certain varying rule and random variable. The evolution mechanism of urban grid disaster will be analyzed to uncover the spread process of it using random fluctuations. And then such problems as the electric vehicle load mathematical model building, electric load probability model description and the power plow calculation in disaster evolution after large-scale access of electric vehicles will be solved. On the basis of that, the disaster resistance index of the urban power grid considering the varying load will be defined and the probability of disaster resistance capability of the urban power grids will be evaluated with the index. The research of the project will provide some theoretical support for disaster resistance analysis of the popularity and large-scale access of electric vehicles and the urban grids and grids planning.

电动汽车并网后，城市电网的潮流变化具有一定的随机性，使城市电网的灾变机理更加复杂，也使其遭受安全威胁的可能性大大增加。因此，对大规模电动汽车并网运行模式下，城市电网灾变机理和抗灾变能力评估的研究迫在眉睫。本项目根据电动汽车充放电和电力负荷变化的规律性与随机波动特性，引入动态随机变量，通过确定的变化规律与随机变量的叠加来描述电动汽车充电负荷和电力负荷的动态概率模型，计算动态概率潮流，对V2G运行模式下城市电网的灾变机理进行分析，揭示其故障事件的蔓延过程。解决电动汽车大规模接入后电动汽车充电负荷数学模型建模难、电力负荷概率模型描述难和灾变演化过程中潮流计算难等问题。在此基础上，定义考虑负荷随时间变化的城市电网抗灾变指标，并完成在新指标下城市电网抗灾变能力的概率性评估。课题的研究将对电动汽车的普及、大规模接入城市电网的抗灾变能力分析以及城市电网规划提供一定的理论支撑。

城市电网处于电力系统末端，是电力系统重要的组成部分，实现电动汽车与电网双向能量传输(vehicle to grid, V2G)模式是未来城市电网的一大特色。电动汽车规模化无序充电会使城市电网负荷“峰上加峰”，造成城市电网可靠性降低，电能质量恶化，因此在V2G模式下，积极引导电动汽车有序充电，制定合理的电动汽车充放电控制策略，进而研究电动汽车并网对城市电网可靠性、安全风险及电能质量的影响等方面的研究具有重要的意义。. 本项目基于电动汽车行驶特性、电池特性等约束条件建立了电动汽车充放电功率的动态概率模型，综合考虑电动汽车V2H、V2G模式下城市电网负荷峰谷差、日负荷率、负荷均方差和用户电费进行多目标优化，制定电动汽车调度策略；将动态概率潮流应用于V2G模式下城市电网电压质量评估，求得城市电网节点电压概率分布，进而得到城市电网电压合格率，评估V2G模式下城市电网的电压质量；基于电动汽车动态概率模型，提出一种V2G模式下计及设备开断概率和负荷转移概率的配电网可靠性评估算法，建立电动汽车充放电随机性与供电可靠性之间的映射，分析V2G模式下城市电网的可靠性。. 本项目通过对V2G模式下电动汽车调度策略、电能质量、城市电网可靠性等方面的研究，为未来电动汽车的普及以及城市电网规划提供了重要的理论支撑和技术参考。