Research on Rotor Protection Scheme for Variable Speed Pumped Storage Units

Variable speed pumped storage units utilize three-phase low-frequency AC excitation, and the probability of internal failure in rotor windings is high. However, the existing rotor protection systems do not adequately meet safety and sensitivity requirements. This paper analyzes the rotor low frequency signal acquisition technology because of the low frequency signal transformation problem of the electromagnetic instrument transformer. This paper simulates and analyzes the fault characteristics of rotor single phase grounding and short circuiting between phases via resistance under power generation, pumping and startup conditions, puts forward the protection criterion that reacts to changes in the amplitude of three phase voltage of the rotor, and based on this, puts forward a comprehensive rotor protection scheme that is effective in reflecting the weak faults of rotor faults.