A Rotor Protection Scheme Extracting the Main Stator Harmonics of Variable Speed Pumped Hydro Machines

The protection of rotor winding in variable speed pumped hydro (VSPH) machines is currently a research hotspot in the energy storage field. In this paper, based on the rotor winding internal fault characteristics of the VSPH machines, the fast Fourier transform (FFT) algorithm is used to calculate the amplitudes of FFT spectral lines that correspond to the main harmonic components in the stator winding. Subsequently, a rotor protection scheme is introduced based on the distinctive features of FFT spectral lines to distinguish between internal and external faults. Simulation results using a multi-loop model of an AC excitation dynamic electrical machine demonstrate that the proposed protection scheme can quickly and sensitively respond to the rotor winding internal fault.