The Torsional Vibration of Turbo-Generator Groups in Mechanically and Electrically Coupled Influences

Under the interactions between the power network and mechanical system, torsional vibration, of large turbine-generator rotor strings, has occurred. Taking a 300 MW turbine-generator as the subject of study, simulation tests, of electrically-mechanically coupled sub-synchronous vibration of the rotor strings, have been performed. The results show that: in three phase short circuit accidents, circuits with series capacitance compensation have an even stronger effect to shafts´ torsional vibration response, than those without such compensation; with increasing degree of compensation, the sub-synchronous resonance current in the power system increases remarkably, as does the danger of sub-synchronous mechanically-electrically coupled vibration.