Research on the mechanism of bending and torsional vibration of rotor induced by winding inter-turn short-circuit in large synchronous condenser excitation

The synchronous condenser plays a crucial role in reactive power compensation and voltage support in ultra-high voltage direct current power grids. Vibration is a key bottleneck for the safe and stable operation of the synchronous condenser, especially rotor vibration resulting from electromagnetic torque caused by inter-turn short-circuit. This article takes a 300 MV large synchronous condenser as the research object, and studies the influence of electromagnetic torque caused by inter-turn short-circuit on the vibration of the rotor. Through theoretical analysis and finite element simulation, a theoretical model and a finite element model of rotor bending-torsional coupled vibration were established, and the accuracy of the theoretical model was validated experimentally. The results show that: The first three bending frequencies are 11.93 Hz, 31.27 Hz, and 89.46 Hz; Under both static and dynamic imbalance conditions, the vibration amplitude of the rotor increases with the increase of the shorted turn ratio; The vibration amplitude before and after being stimulated under dynamic unbalance is larger than that under static imbalance. The research results can provide a theoretical basis for the design and safe operation and maintenance of the synchronous condenser.