Critical Nodes Identification of Complex Power Systems Based on Electric Cactus Structure

Malfunction of critical components in the power system can lead to large scale cascading failures and blackouts. Identifying critical components and taking protection on them can prevent the above problem effectively. In this article, investigating from the sight of network dynamics, a critical node identification method of complex power systems is proposed to find the nodes that have a great influence on the controllability and observability of the power system. First, based on electrical betweenness, a directed network model of power systems is proposed, which solves the problem that assessment results are not accurate because the traditional network model only represents the structural characteristics of power systems at a certain time. Then, combining structure controllability theory and the electrical characters of power systems, the electric cactus structure is established to provide a theoretical basis for assessment indexes. The node number of electric cactus is defined as the electric control capability index (ECCI), which measures the node's influence on the controllability of power systems. Besides, based on the duality principle and ECCI, the electric observe capability index is defined to measure the node's influence on the observability of power systems. Combining the two capability indexes, the electric dynamic characteristic index is defined. Finally, the method has been demonstrated on the IEEE 118-bus system. The results show that the identified nodes have a strong impact on the controllability and observability of the IEEE 118-bus system.