Calculation of Short-Circuit Current of Doubly-Fed Variable-Speed Pumped Storage Unit

The calculation of short-circuit current of doubly-fed variable-speed pumped storage unit (DFVSPSU) is studied, this paper studies the analytical expression of short-circuit current from the flux transient process. Based on the transient analysis method of three-phase short-circuit current of DFVSPSU, this paper firstly establishes the mathematical model of DFVSPSU and the transient equivalent circuits of stator and rotor when three-phase short-circuit fault occurs in the grid. The transient process of stator and rotor flux faults is analyzed, and then the expressions of steady-state and transient components of stator flux after faults are obtained. On this basis, the expression of three-phase short-circuit current of DFVSPSU is derived. Simulation verifies the accuracy of the three-phase current expression proposed in this paper. This paper studies the influence of the distance between the short-circuit point and DFVSPSU on the feedback short-circuit current under pumping operation mode, and proposes the distance of short-circuit point that can ignore the influence of feedback short-circuit current, which provides technical support for safe and stable operation of pumped storage power station.