Robust Nonlinear Controller to Damp Drivetrain Torsional Oscillation of Wind Turbine Generators

This article develops a novel nonlinear controller for the mitigation of drivetrain torsional oscillations of wind turbine generators following large disturbances. The key idea is to integrate differential geometry theory with an extended state observer. Differential geometry allows transforming the wind turbine generator nonlinear model into a simple second-order Brunovsky system, whereas the extended state observer can accurately estimate the states of the transformed Brunovsky system and compensate unknown disturbances. Simulation results show that, under various conditions in different test systems, the proposed controller achieves significant enhancements with respect to conventional approximate linearization-based controller and nonlinear sliding mode control-based method.