Simulation Study on Interturn Short Circuit of Rotor Windings in Generator by RSO Method

For better application of recurrent surge oscillograph (RSO) method to diagnose the interturn insulation of generator rotor, the response characteristics of repetitive pulse and fault location algorithm under interturn short circuit fault are studied in this paper. Firstly, the R-L and R-C ladder equivalent circuit of generator rotor windings and its equivalent circuit number per unit length are determined by the improved vector fitting algorithm, then the time domain response of RSO signal propagating in generator rotor winding is simulated by circuit simulation software. The simulation results indicate the effectiveness of improved vector fitting algorithm. And it also indicates that this algorithm has the advantages of high operational efficiency and easy application at the field. Finally, to realize the quantitative analysis of the fault, the fault se-verity factor is proposed to characterize the fault severity. The calculation is made by changing the position of fault, the length of interturn short circuit and the reference so as to study on the change trend of the fault severity factor. The results show that the fault severity factor can represent the severity of the fault objectively, which is proportional to the degree of short circuit, and is related to the fault distance, but has nothing to do with the reference.