Progress in Implementing and Testing State-Space Controls for the Controls Advanced Research Turbine: Preprint

Designing wind turbines with maximum energy production and longevity for minimal cost is a major goal of the federal wind program and the wind industry. Control can improve the performance of wind turbines by enhancing energy capture and reducing dynamic loads. At the National Renewable Energy Laboratory (NREL) we are designing state-space control algorithms for turbine speed regulation and loadreduction and testing them on the Controls Advanced Research Turbine (CART). The CART is a test-bed especially designed to test advanced control algorithms on a two-bladed teetering hub upwind turbine. In this paper we briefly describe the design of control systems to regulate turbine speed in region 3 for the CART. These controls use rotor collective pitch to regulate speed and also enhancedamping in the 1st drive-train torsion, 1st rotor symmetric flap mode, and the 1st tower fore-aft mode. We designed these controls using linear optimal control techniques using state estimation based on limited turbine measurements such as generator speed and tower fore-aft bending moment. In this paper, we describe the issues and steps involved with implementing and testing these controls onthe CART, and we show simulated tests to quantify controller performance. We then present preliminary results after implementing and testing these controls on the CART. We compare results from these controls to field test results from a baseline Proportional Integral control system. Finally we report conclusions to this work and outline future studies.