Design of Modern Controls for the Controlled Advanced Research Turbine (CART)

Control can improve the performance of wind turbines by enhancing energy capture and reducing dynamic loads. At the National Renewable Energy Laboratory, we are designing control algorithms for regulation of turbine speed and power using state-space control methods. In this paper, we describe the design of a control algorithm for regulation of rotor speed in full-load operation (region 3) for the Controlled Advanced Research Turbine (CART). This turbine is a two-bladed, teetering hub, upwind machine, adapted for testing a variety of control algorithms. We base our control design on simple linear models of a turbine, which contain rotor and generator rotation, drivetrain torsion, rotor flap, and tower fore-aft bending degrees of freedom. We account for wind-speed fluctuations using disturbance accommodating control (DAC). We show the capability of these control schemes to stabilize the modeled turbine modes via pole placement while using state estimation to reduce the required number of turbine measurements. We test these algorithms through simulation, incorporating them into two simulation codes and simulating the controlled system for various operating conditions. Finally, we report conclusions to this work and outline future studies.