Faulty Phase Selection and Location Method of Rotor Ground Fault for Variable Speed Pumped Storage Generator-Motor

The rotor winding of variable speed pumped storage generator-motor (VSPSGM) is a special three-phase winding structure, which not only makes the traditional rotor ground fault location method no longer applicable, but also increases the faulty phase selection problem. Therefore, the faulty phase selection and location method of rotor ground fault for VSPSGM is proposed in this article. Firstly, the relationship between the phase characteristics of the rotor winding potential and the working conditions is summarized according to the generation mechanism of the induced potential. The piecewise function is used to accurately analyze the amplitude and phase variation of the winding potential. On this basis, a reliable faulty phase selection method for rotor ground fault is proposed based on phasor trajectory analysis. Furthermore, the optimization model of ground fault location is constructed according to the geometric relationship of neutral point to ground voltage phasor, fault point to ground voltage phasor, and fault winding potential phasor. The accurate position of the ground fault can be obtained by solving the optimization model. This technique has been validated through simulations and experimental tests.