中文摘要：

大规模电动汽车入网,不仅会增加有序充电控制的复杂度,还会引发负荷节点电压越限等配电网安全问题。在考虑负荷节点电压等配电网安全约束的情况下,提出基于改进贪心算法的大规模电动汽车充电优化策略。在建立电动汽车充电优化模型的基础上,通过设计合理的贪心策略,克服了贪心算法容易陷入局部最优的缺陷,实现电动汽车的最优充电控制。利用贪心算法的灵活性,提出对节点电压和线路容量分时段控制的配电网安全控制策略,迭代求解满足约束的充电站容量上限,降低了问题求解的难度。最后,以包含3个本地代理商的IEEE 33节点配电系统为例进行仿真分析。结果表明：改进贪心算法具有较高的计算效率和较好的寻优特性,适用于大规模电动汽车的充电优化;配电网安全控制策略能够确保负荷节点电压在安全约束之内,减少充电负荷对本地配电网电能质量的影响。

英文摘要：

Large- scale plug- in of EVs（Electric Vehicles） not only increases the complexity of coordinated charging control but also impacts on the security of distribution network,such as load bus voltage violation.With the consideration of distribution network security constraints,a strategy of EVs charging optimization based on the improved greedy algorithm is proposed. Based on the established EVs charging optimization model,a reasonable greedy strategy is designed to avoid the local optimum and realize the optimal EVs charging control.Due to the flexibility of greedy algorithm,a strategy of distribution network security control is proposed to control the bus voltage and line capacity for a time interval,which,with less difficulty,solves the upper limit of charging station capacity iteratively. An IEEE 33-bus distribution system with three local agents is simulated and the simulative results show that,the improved greedy algorithm has higher computing efficiency and better global optimization ability,suitable for the charging optimization of massive EVs;the strategy of distribution network security control ensures the load bus voltage within its limits and suppresses the impact of charging load on the power quality of local distribution network.