Limitation of Weakly Damped Shaft Lines Power Stations Torsional Vibrations at Subsynchronous Frequencies in Distributed Generation Power Systems

The possibility of limiting the amplitude of the turbine shaft line torsional vibrations by introducing additional units into the automatic excitation regulator of the generator is studied. The mathematical model of the power system, including the electric and mechanical subsystem of the turbine, is developed. The structure of an automatic excitation regulator is given. A quadratic controller is implemented that makes to reduce the amplitudes of torsional oscillations. The system is modeled without the controller and with it. The dependence of the amplitude of the torsional oscillations on the gain factor of the controller is obtained. By this dependence it can be concluded that the increase of the coefficient of the quadratic controller makes it possible to reduce the amplitude of the oscillations.