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

2. 2 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

3. 3 2006 Wind Program Peer Review Commercial Turbine Control Generator Torque Nacelle Yaw Blade Pitch Control Actions

4. 4 2006 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

5. 5 2006 Wind Program Peer Review Adaptive control 0.3% - 5% energy capture increase

6. 6 2006 Wind Program Peer Review Control of Flexible Modes

7. 7 2006 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

8. 8 2006 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

9. 9 2006 Wind Program Peer Review Process/Tools DesignSimulate Linear ModelFAST DACADAMS LQRSimulink Field test CART CART-3 Industry Modify Analyze data Make changes Iterate

10. 10 2006 Wind Program Peer Review Field Tested Collective Pitch Controller 15% - 50% reduction in Shaft Torque fatigue loads

11. 11 2006 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

12. 12 2006 Wind Program Peer Review Disturbance Model h z hub V h z V Uniform wind component Fluctuating wind component

13. 13 2006 Wind Program Peer Review Simulated Control With New Independent Pitch/DAC Must measure either tip- deflection or flap-bending moments on each blade

14. 14 2006 Wind Program Peer Review Use of Lidar Measured Wind-speed  Simulated single lidar hub-mounted on CART  Conical scan achieved through rotor rotation

15. 15 2006 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)535183 64 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)295263310278

16. 16 2006 Wind Program Peer Review No controlControl Measured Tower Load Reduction Using Generator Torque Control (CART)

17. 17 2006 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

18. 18 2006 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.

19. 19 2006 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

20. 20 2006 Wind Program Peer Review Opportunities  Partner with industry to implement controls on large turbines.  Develop controls test-bed/floating platform simulator.

21. 21 2006 Wind Program Peer Review Questions and comments