Wind_Energy_Essentials_Lecture 8

Controller actuator car sensor measured velocity

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Unformatted text preview: 010 Control Design Slope of Road / Uncertain Mass Desired Velocity Error Throttle Cmd. Controller Actuator Car Sensor Measured Velocity • Objective: Maintain the desired velocity • Considerations: – – – – Transient response (rise time, overshoot) Changes in desired velocity Driver comfort (control effort) Disturbances, model uncertainty, sensor noise Control Design Slope of Road / Uncertain Mass Desired Velocity Error Throttle Cmd. Controller Actuator Car Sensor Measured Velocity • Design Process 1. 2. 3. 4. 5. Model the system: Differential equations Design the controller: PID control is a basic technique Analyze and simulate: Theory + MATLAB Implement the controller and experiment Iterate 11 11/9/2010 Proportional-Integral-Derivative (PID) Control velocity (mph) 65 e(t) vd(t) 55 Past Present Future time (sec) Amazing Property Of Integral Action • Integral control • Assume: there is a steady-state • Then: • Proof: • Impossible unless 12 11/9/2010 Advanced Control Design • Observer-based design • MIMO • Robust • Nonlinear • Adaptive • Distributed Feedback Control of Wind Turbines • Increase captured power • Reduce structural loads • Sequence operation modes • Fault detection and diagnostics 13 11/9/2010 Wind Turbine Modeling • Focus on modeling of an individual turbine – Ignore aerodynamic interactions between turbines in a wind farm • Tradeoff between model fidelity and complexity • Reasonably accurate models of low complexity are most useful for control design Available Wind Power • Available Power: – – – – Pwind = 1 ρAv 3 2 2 1 Kinetic energy density: 2 ρv Volume flow across rotor in time dt: Avdt Energy flow across rotor in time dt: dE = 1 ρAv 3 ( Avdt ) 2 Pwind = dE/dt vdt ( ) v R ω A= πR2 14 11/9/2010 Aerodynamic Efficiency, Cp • Cp := Pcaptured Pwind = C p (β , λ ) – β=Collective blade pitch ωR – λ=Tip speed ratio = v • Cp does not account for losses in gearbox, power electronics, etc • Cp shown for Controls Advanced Research Turbine (CART) at NREL – 600kW, R=21.7m Figure from:...
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