Effect analysis of rotor interturn short circuit fault detection for pumped storage unit under multiple working conditions

The rotor winding inter-turn short circuit fault forms an unbalanced magnetic pull inside the pumped storage unit, which can lead to severe vibration of the unit. It is necessary to accurately and real-time detect the fault. The U-type detection coil installed on the stator core of the unit is used to detect the inter-turn short-circuit fault of the rotor in view of the variable operating conditions of the pumped storage unit. Taking a 322 MW pumped storage unit in a hydropower station as an example, the typical working conditions of no-load condition, rated load, power generation phase modulation, motor load and electric modulation were simulated by finite element software. The inter-turn short-circuit fault of the rotor winding in different degrees was simulated. The results show that the fractional harmonics appear in the induced electromotive force of the detection coil after the fault, and the amplitude increases with the rise of the fault degree. It is proved that the U-type detection coil can effectively reflect the inter-turn short circuit fault of rotor winding under multiple working conditions of pumped storage units. Therefore, the U-type detection coil method is suitable for online diagnosis of inter-turn short circuit fault of rotor winding of pumped storage units. © 2023 Editorial Department of Electric Machines and Control. All rights reserved.