1. ME 252 Thermal-Fluid Systems G. Kallio
Wind Turbine Systems
ME 252
Thermal-Fluid Systems
G. Kallio

2. Introduction
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Wind Turbine Systems

3. California Wind Power Project MW Installed Energy Output (1998)
California leads nation in installed wind power systems; Texas is 2nd with 1052 MW
Project
MW Installed
Energy Output (1998)
San Gorgonio Pass
615.89
805 M kWh
Tehachapi
608.72
1.2 B kWh
Altamont Pass
548.32
637 M kWh
Solano County
240.78 NA
Pacheco Pass
16.0
Others
0.675
TOTAL
2030
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Wind Turbine Systems

4. Economics
Capital costs: turbines (49%), towers (10%), construction (22%)
Trends
Rotor size: 10  71 m
Power/unit: 25  1650 kW
Cost/kW: $2600  $790
Capacity factor: 21%  39%
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Wind Turbine Systems

5. Turbine Design
Most common design is the horizontal axis wind turbine (HAWT)
Other types
VAWT
Drag vs. lift types
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Wind Turbine Systems

6. Wind Turbine Power Curve
Power curve for a 600 kW-rated turbine
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Wind Turbine Systems

7. Components
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Wind Turbine Systems

8. Rotor Rotor consists of hub and blades
Most turbines use upwind rotors with three blades made from fiberglass reinforced plastics (GRP)
NACA airfoil shapes used for outermost blade profile
Blade power control
Passive stall control: blades have fixed pitch and designed to stall at high wind speeds
Pitch control: blade pitch is variable and controlled to optimize power output
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Wind Turbine Systems

9. Rotor Size
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Wind Turbine Systems

10. Drive Train
Parts include a low-speed shaft (from rotor), gearbox, high-speed shaft (to generator), bearings, brake, and couplings
Input shaft: rpm
Output Shaft: usually 1800 rpm
Types of gearboxes
Parallel shaft
Planetary
Brake: used to stop rotation during maintenance or down-time
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Wind Turbine Systems

11. Generator Types Variable speed vs. variable slip
Synchronous
Asynchronous (induction)
Variable speed vs. variable slip
Most grid-connected systems use an asynchronous generator, due to ruggedness, low cost, and easy grid connection; but stator requires power from external source
Stand-alone systems often use a synchronous generator
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Wind Turbine Systems

12. Yaw Mechanism
Yaw error occurs when the rotor is not aligned perpendicular to the wind direction, producing less power and higher fatigue loads
Most upwind HAWT use forced yawing, where electric motor(s), gearing, wind sensor, cable twist counter, and control system align the rotor with the wind
Free yawing (self-aligning) systems are commonly used on downwind rotor turbines
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Wind Turbine Systems

13. Control System
Goals
maximize power production
maximize fatigue life of all stressed components
Limit drive train torque/power
Sensors – velocity, position, temperature, current, voltage, etc.
Controllers – electronics, computers, mechanical mechanisms
Power – switches, electrical amplifiers, hydraulic pumps, valves
Actuators – motors, pistons, magnets, solenoids
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Wind Turbine Systems

14. Tower Primary tower types
Tubular steel
Lattice (truss)
Guyed
Height: want at least 20m up to 1.5 times the rotor diameter; tallest towers are around 110m
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Wind Turbine Systems