Probabilistic Connectivity Performance of Power Network Topology Variation Trajectory

The cascading failure is accompanied by a sustained reduction in the topological connectivity of the network until the network is disconnected. From the perspective of the contingency analysis, the number of topological change trajectories of a cascading failure process is large, and the enumeration representation is cumbersome. In order to make full use of all the information of the topology variation trajectory space effectively and simply, the method of probability analysis is worth considering. First, this paper defines the probabilistic connectivity matrix of the network to describe the connectivity characteristics of the variation trajectory space. Second, the variation-connectivity sequence is defined according to the N-k connectivity expectation and the network disconnection probability. This sequence formulates the topological connectivity of the variable power network. Third, this paper gives a method to judge the strength of the variation of power network connectivity. Fourth, this paper defines the variation-connectivity sequence of the main grid. The results of the studies on several power network cases show that the variation-connectivity sequence can well describe the connectivity of the variable power network, and help to reveal the topological evolution characteristic of the power network in the cascading failure process.