Fault transient calculation on condition of system swing and analysis of relaying protection

For calculating the fault transient on condition of system swing, changes of frequency and angle are taken into account in this paper. Considering the salient-pole reaction, stator coil transient and rotor coil mechanical characteristics, the united synthetic companion model of synchronous generators is built by integrating the electromagnetic transient, mechanical transient and port equation of synchronous generators. Based on the spectral analysis, the modified Euler model can not only avoid oscillation of numerical calculation but also improve the simulating accuracy. The fault electromagnetic transient on condition of system swing is simulated by synthetic companion model of generator. Distance protection element of LFP-901A, the transmission line protection, is taken for example to analyze action of the protection and its swing block component on condition of system swing.