Active control and simulation test study on torsional vibration of large turbo-generator rotor shaft

Reduction of shaft vibration is very important for safe and efficient functioning of a large turbo-generator. This paper presents a theoretical study and proposes an active vibration control scheme for controlling torsional vibration of a rotor shaft due to electromagnetic disturbances or unsteady flow in large steam turbine generator sets. A form of the conventional linear quadratic regulator (LQR) control algorithm has been proposed in this paper. The optimal LQR control problem is solved for each time interval with the weighting matrices, through the Ricatti equation, leading to time-varying gain matrices. The test is conducted using modified direct current electromotor as torsional vibration exciter and actuator, mounting on the rotor shaft. The actuator applies suitable force to control torsional vibration. Suitable force of actuation is achieved by varying the control current in the actuator depending upon a proportional and derivative control law. Preliminary theoretical study and test simulation show good reduction in torsional vibration response.