Bumpless Transfer of Parametrized Multivariable Disturbance Observer Based Controller to Reduce Cyclic Loads of Wind Turbine

This paper is concerned with bump-less transfer of parametrized disturbance observer 1 based controller (DOBC) with Individual Pitch Control (IPC) strategy for full load operation of wind 2 turbine. Aerodynamic cyclic loads are reduced by tuning multivariable DOBC with the objective 3 to reduce output power fluctuation, tower oscillation and drive-train torsion. Furthermore tower 4 shadow and wind shear effect are also mitigated using parametrized controller. A scheduling 5 mechanism between two DOBC is developed and tested on Fatigue, Aerodynamics, Structures, and 6 Turbulence ( FAST) code model of National Renewable Energy Laboratory (NREL)’s 5 MW wind 7 turbine. The closed-loop system performance is assessed by comparing the simulation results of 8 proposed controller with a fixed gain and Linear Parameter Varying (LPV) DOBC with Collective 9 Pitch Control (CPC) for full load operation. It is tested with step changing wind to see the behavior 10 of the system under step change with wind shear and tower shadow (cyclic load) effects. Also 11 turbulent wind is applied to see the smooth transition of the controllers. It can be concluded from 12 the results that the proposed parametrized control DOBC with IPC shows smooth transition from 13 one controller to another by interpolation. Moreover fatigue of the gear and tower due to wind 14 shear and tower shadow effects are reduced considerably by the proposed controller as compared 15 to collective pitch control. 16