中文摘要：

电网中少数关键节点的故障可能会引发连锁故障,从而对电网的安全稳定运行造成巨大影响。因此,识别出电力系统的关键节点并进行重点保护对预防重大停电事故具有重要意义。在此背景下,该文提出了基于改进节点重要度贡献矩阵的电网关键节点的识别方法。首先,基于功率转移分布因子（power transfer distribution factors,PTDF）定义改进的电气距离,在此基础上提出了反映节点间连通性的节点效率指标;接着,为了更好地体现节点的局部和全局重要性,对节点重要度贡献矩阵进行改进,并提出基于改进节点重要度贡献矩阵的节点重要度评估方法;然后,为了比较不同关键节点识别方法的优劣,提出并定义了网络可供电能力和网络效能指标;最后,基于新英格兰10机39节点系统,通过模拟对关键节点的攻击以及与其他方法的比较,验证所提出的关键节点识别方法的有效性和正确性。

英文摘要：

The failure of a few critical nodes in power systems may lead to cascading failures,which has a great impact on the secure and stable operation of the power systems. Thus,the identification and safeguard of critical nodes in power systems are of great importance for relieving the influence of power outages. Under this background,this paper proposes an identification method of critical nodes in power systems based on improved node importance contribution matrix. Firstly,the improved electric distance is defined based on power transfer distribution factors（ PTDF）,and then nodal efficiency for reflecting the connectivity among the nodes is defined. Then,the node importance contribution matrix is modified for better describing the local and global importance of nodes comprehensively,and the evaluation method of node importance based on the improved node importance contribution matrix is presented. Next,in order to compare the superiority between different identification methods of critical nodes,the ability of power supply and network performance are proposed and defined. Finally,the simulation of attack on critical nodes in New England 39-bus system and the comparison with other methods are employed to further verify the effectiveness and validity of the proposed identification method of critical nodes.