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The impedance matrix (Z-matrix) of power system contains much useful and unrevealed information. It has been widely used for short-circuit analysis, contingency analysis and economic dispatch. Based on the electrical coupling paths described by physical parameters of equivalent network derived from the reduced impedance matrix, some novel physical topological analysis methods to identify cut edges, cut vertices and radial paths in the relay coordination and fault analysis software are proposed. The formation of the impedance matrix is the fundamental work of the fault analysis and relay coordination. The physical methods proposed thoroughly utilise the topological information concealed in the existent Z-matrix. Compared with the traditional graph-theoretical approaches, the physical one has clearer and more significant physical implication that may help to understand and give insight into the study of the topology of the electrical network topology in power system comprehensively. Examples are presented to prove the consistency of physical topology in power system with the corresponding geometrical topology. The efficiency of the physical methods to improve network topology analysis has also been validated.