In view of the demand on instantaneity and accuracy in power network topology analysis

this paper puts forward a new method of network topological analysis based on the incidence matrix notation method and the loop matrix. Under normal circumstances

the initial distribution of electrical islands is determined by using the incidence matrix notation method. Meanwhile

trees and link lines are marked. When the network topology is changed

the attributes of the changed branch are judged through the loop matrix. Then

part of the network topology is modified and the loop matrix is updated using the broken circle method and the radius search method. Finally

results of the IEEE 39-bus and IEEE 118-bus systems have both verified that the proposed method is of low computational complexity and is capable of being applied to variable network structures.