Advanced Controls Research Alan D. Wright Lee Fingersh Maureen Hand Jason Jonkman Gunjit Bir 2006 Wind Program Peer Review May 10, 2006

Wind Program Peer Review  Create design methodology for advanced controls: –regulate rotor-speed and/or maximize energy extraction. –stabilize important flexible modes of the turbine to reduce dynamic loads and response.  Develop control design and modeling tools.  Develop controls field testing capability. Objectives

Wind Program Peer Review Commercial Turbine Control Generator Torque Nacelle Yaw Blade Pitch Control Actions

Wind Program Peer Review What else can we do?  Improve energy capture –Active rather than passive rotor control Negative inertia - Use of shaft torque to cancel rotor inertia –Adaptive control –Active pitch following –Optimal torque control  Reduce loads –Load feedback –Independent pitch control –Periodic gains –Active tower / blade / drive-train damping –Advanced sensors –Look-ahead controls

Wind Program Peer Review Adaptive control 0.3% - 5% energy capture increase

Wind Program Peer Review Control of Flexible Modes

Wind Program Peer Review  Regulate rotor-speed in the presence of wind-speed disturbances and stabilize turbine modes. –Stabilize flexible modes through full state feedback. –Use state estimation to provide the controller with needed states (including wind-speed). –Represent wind disturbance with extra states. Controller accounts for fluctuating wind speeds and shears.  Multiple input/multiple output, single control loop State Feedback Control

Wind Program Peer Review State-Space Linear Model  Linear time-periodic model Structural DOFs & rates Pitch actuator states Wind disturbance Up to 17 states Turbine measurements State matrices periodic over each rotation Up to 9 measurements Tower & blade strain gauges LSS torque Yaw, teeter, LSS angles Pitch angles where

Wind Program Peer Review Process/Tools DesignSimulate Linear ModelFAST DACADAMS LQRSimulink Field test CART CART-3 Industry Modify Analyze data Make changes Iterate

Wind Program Peer Review Field Tested Collective Pitch Controller 15% - 50% reduction in Shaft Torque fatigue loads

Wind Program Peer Review CART Test Results – Pitch Control Normalized to Baseline Controller Performance  Significant reduction in most measured loads (30-70%) Region 2 Region 3

Wind Program Peer Review Disturbance Model h z hub V h z V Uniform wind component Fluctuating wind component

Wind Program Peer Review Simulated Control With New Independent Pitch/DAC Must measure either tip- deflection or flap-bending moments on each blade

Wind Program Peer Review Use of Lidar Measured Wind-speed  Simulated single lidar hub-mounted on CART  Conical scan achieved through rotor rotation

Wind Program Peer Review Simulated Results Steady 18 m/s wind, power law exponent = 0.17 Steady 18 m/s wind, power law exponent = 0.3 DACDAC + LIDARDACDAC + LIDAR Blade 1 RFB moment DEL (kNm) Turbulent 18 m/s wind, power law exponent = 0.17 Turbulent 18 m/s wind, power law exponent = 0.3 DACDAC + LIDARDACDAC + LIDAR Blade 1 RFB moment DEL (kNm)

Wind Program Peer Review No controlControl Measured Tower Load Reduction Using Generator Torque Control (CART)

Wind Program Peer Review Conclusions 17  Must move away from using old control schemes with multiple loops  Advanced Controls show great potential for meeting multiple control objectives –Stabilizing turbine structure –Enhancing energy capture –Mitigating dynamic loads  Will be critical for large flexible machines as well as offshore turbines with many flexible modes

Wind Program Peer Review Plans - Future Work  Complete development of control design tools for industry.  Continue advanced controls development and testing.  Develop new field testing capability on a large flexible turbine – partner with industry.  Implement and test controls on commercial turbines.

Wind Program Peer Review CART-3 – 3-bladed hub testing  Supplement to the 2-bladed CART  Advanced controls integration  Designed for testing modern controls –Loads –Deflection –Advanced sensors

Wind Program Peer Review Opportunities  Partner with industry to implement controls on large turbines.  Develop controls test-bed/floating platform simulator.

Wind Program Peer Review Questions and comments