Efficient modification of the control system in PMSG-based wind turbine for improvement of the wind turbine dynamic response and suppression of torsional oscillations

This paper first deals with the dynamic performance evaluation and stability analysis of permanent magnet synchronous generator-based wind turbine. Then, the permanent magnet synchronous generator speed control system is modified, and an efficient control approach is proposed for suppression of electromechanical oscillations in drive train system. Generator speed feedback-based active compensation techniques employing high pass, band pass, or notch filters have been widely used to actively damp the torsional electromechanical oscillations in variable speed wind turbines. However, usefulness of these approaches is highly dependent on the filter parameters, and thus, their performance may be failed when existing uncertainty in shaft stiffness changes the drive train resonance frequency. To overcome this issue, a new active method is proposed for damping improvement of drive train torsional oscillations. The proposed method increases the effective damping of the drive train system by adding a damping torque component that is proportional to the speed difference between the turbine and generator. The speed difference between the turbine and generator is provided by estimation of shaft torsional torque. It is shown that the proposed active damping method has superior efficacy in damping of torsional electromechanical oscillations with and without considering the model uncertainty.