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Unformatted text preview: , Wind Energy Handbook, Chapter 8: The Controller, 2001. – J. Laks, L. Pao, and A. Wright, Control of Wind Turbines: Past, Present and Future, American Control Conference, 2009. 20 11/9/2010 System Components Figure from the US DOE Power vs. Wind Characteristics
Region 3: Rated Power+ Load Reduction Region 2: Maximize Power Cut-in Cut-out Plot based on Clipper Liberty C100 2.5MW turbine (R=50m, Vcutin = 4m/s, Vcutout = 25m/s) assuming Cp,max = 0.4 21 11/9/2010 Supervisory Control
• Supervisory control switches turbine between modes based on wind conditions, startup, and emergency stops • Logic for Clipper’s Liberty Wind Turbines:
– Slide 27 of September 9 talk by Steve Owens shows the operating states for Clipper’s Liberty Turbines – Turbine cut-in at 4m/s based on 10min average – Turbine cut-out at 25m/s based on 10min average Yaw Control
• Yaw rotor into wind in both regions 2 and 3 • Yaw dynamics are slow due to large nacelle mass
Wind Heading Yaw Cmd. Measured Yaw Angle Error PID Actuator Yaw Dyn. Sensor 22 11/9/2010 Region 2 Control
• Objective: Maximize power capture by holding β=βopt (constant) and using τg to track λopt Figure from: K. Johnson, L. Pao, M. Balas, and L. Fingersh, Control of Variable Speed Wind Turbines, IEEE Control Systems Mag., June 2006 Region 2: Possible Control Strategy
• Compute desired rotor speed using the optimal tip speed ratio (TSR) and measured wind speed.
ωdes = λopt v
R • Issues:
– Shadowing effects corrupt wind speed measurement – Uncertainty in power coefficient model
Measured Wind Speed TSR Relation Optimal TSR βopt Desired Rotor Speed Error PID τg Turbine wind Measured Rotor Speed 23 11/9/2010 Region 2: Standard Controller
• Control Law
τ g = Kω 2
3C where K = 1 ρAR λ 2
p ,max 3 max – Ref: Johnson, et al, 2006 Control System Mag. – For typical operating conditions, convergence to optimal power capture in steady state – Only requires rotor speed sensor – Control law still depends on uncertain power coefficient model. Adaptive l...
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- Spring '11