Design of a Tower and Drive Train Damping Controller for the Three-Bladed Controls Advanced Research Turbine Operating in Design-Driving Load Cases

Wind turbines experience both fatigue and extreme loading, and individual components of a wind turbine are affected differently by these loads. The current practice to achieve the typical 20 year design life is to build a turbine with robust components that can withstand fatigue and extreme loads for this duration. Unfortunately, overbuilding of components may lead to higher-than-necessary initial capital costs. In this research, we studied design-driving load cases and designed advanced control algorithms aimed at enabling a decrease in initial capital cost. Our approach used a subset of a full International Electrotechnical Commission loads case analysis and selected major components experiencing design-driving extreme loads that can be alleviated using advanced control. We first describe the results from the loads case analysis and then discuss the components on which we focused the advanced control design. We next describe the controller design and finally compare the results from the advanced controller simulations with those using a baseline controller. The baseline consists of a nonlinear torque controller below rated wind speed and a proportional-integral-derivative-like controller above rated and the advanced controller uses proportional feedback and state-space design to reduce tower bending and drive train torsional loads.