Modelling and Control to Mitigate Dynamic Effects of Unbalanced Masses in Wind Turbine Systems

Structural disequilibrium in wind power generating system occurs due to a tolerance in manufacturing, installation defects, and also from an extreme torsional stress that may bring an irreversible displacement in the mechanical structure such as hard stop, extreme wind conditions, and grid faults etc. The unbalanced masses in wind turbine excites vibration forces that affect the life expectancy of the mechanical system as well as the performance of the wind turbine. Hence, the exploration of new control solution for the dynamic torque reduction will be necessary to achieve a more reliable wind power generation. In this paper, a 2.5 MW wind turbine experiencing a mechanical unbalance is modelled and its performance is analysed. A new control algorithm based on generator and planetary gear speed differences is proposed for the dynamic torque reduction. The proposed solution provides a virtual material damping in the system and helps to protect the sensitive driveline components. Simulation results, under 3 different operating regions, illustrate the performance of the control in reducing the dynamic torque amplitudes in wind turbines. The proposed algorithm is experimentally verified in an unbalanced multi-inertia test set up operating under critical speed.