Research on a shaft damping control strategy for DFIG-based wind turbines considering frequency response safety

Abstract

The centralized integration of large-scale wind farms into power grids impairs the frequency regulation capability. The control strategy of wind turbines participating in the system frequency response has attracted wide attention. So far there is few research concerning the effect of frequency response control on the shaft system torsional vibration of the wind turbine drive chain. Thus the safety of wind turbines during the frequency response is yet to be secured. To this end， this paper proposes a strategy to suppress the torsional vibration of the shaft system during the frequency response. A state observer is used to estimate the angular velocity of the drive chain torsion， and the dynamic damping control during the frequency response is achieved using additional torque. The effectiveness of the strategy is verified by comparing it with the existing undamped control strategy through simulation analysis and prototype measurement.

Keywords

• wind turbines
• power grid frequency control
• state observer
• damping
• torsional vibration control