Communications: NREL PowerPoint Presentation Template with Dark Background

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

• 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.

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Commercial Turbine Control
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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

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Adaptive control0.3 - 5 energy capture increase
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Control of Flexible Modes
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State Feedback Control

• 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

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State-Space Linear Model

• Linear time-periodic model

Turbine measurements
Tower blade strain gauges LSS torque Yaw,
teeter, LSS angles Pitch angles
where
Structural DOFs rates
Up to 9 measurements
Pitch actuator states
Wind disturbance
State matrices periodic over each rotation
Up to 17 states
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Process/Tools
Design Simulate Linear Model FAST DAC ADAMS LQ
R Simulink
Field test CART CART-3 Industry
Modify Analyze data Make changes
Iterate
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Field Tested Collective Pitch Controller15 -
50 reduction in Shaft Torque fatigue loads
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CART Test Results Pitch Control
Region 2
Region 3
Normalized to Baseline Controller Performance

• Significant reduction in most measured loads
  (30-70)

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Disturbance Model
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Simulated Control With New Independent Pitch/DAC
Must measure either tip-deflection or
flap-bending moments on each blade
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Use of Lidar Measured Wind-speed

• Simulated single lidar hub-mounted on CART
• Conical scan achieved through rotor rotation

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Simulated Results
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Measured Tower Load Reduction Using Generator
Torque Control (CART)
No control
Control
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Conclusions

• 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

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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.

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CART-3 3-bladed hub testing

• Supplement to the 2-bladed CART
• Advanced controls integration
• Designed for testing modern controls
• Loads
• Deflection
• Advanced sensors

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Opportunities

• Partner with industry to implement controls on
  large turbines.
• Develop controls test-bed/floating platform
  simulator.

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Questions and comments