Study on Torsional Vibration of Thermal Power Units Caused by Wind-thermal Bundled System via Series Compensation

Abstract

Thermal power units which connected to power grid through the series compensated transmission may produce electromechanical torsional vibration interaction. Under certain conditions, the torsional vibration still exists by the wind-thermal bundled power transmission system. With the increase of wind turbine capacity, the electromechanical torsional vibration enhances the role. First of all, the dynamic model of the wind-thermal bundled system is established, including the wind turbine shaft model, the pitch angle control system model, the doubly-fed generator model, the converter control model, the series compensation line model and the rotor shaft model of the thermal power units. Then, the eigenvalue analysis is used to calculate the eigenvalues of the system under different wind-thermal bundled ratios. Finally, the DIgSILENT simulation software is used to obtain the electromagnetic torque response of the turbine generator and the current response of the series compensated lines. Furthermore, the results of eigenvalue analysis are verified by performing spectrum decomposition of the time domain data.