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| | === Aerodynamics<br> === | | === Aerodynamics<br> === |
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| − | === [[Image:Wind turbine blade aerodynamics.jpg|frame|center|Aerodynamics of a wind turbine blade]]Stall<br> ===
| + | [[Image:Wind turbine blade aerodynamics.jpg|frame|center|Aerodynamics of a wind turbine blade]]Stall<br> |
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| − | [[Image:Wind turbine blade aerodynamics - stall control.jpg|frame|center|Wind turbine blade aerodynamics - stall control]]Stall Control:<br>– Passive Stall:<br>Power of the wind turbine is limited by the aerodynamic characteristics<br>of the turbine.<br>– Active stall:<br>Power of the wind turbine is limited additionally by decreasing the pitch<br>angle (increasing the inflow angle ).<br> | + | [[Image:Wind turbine blade aerodynamics - stall control.jpg|frame|center|Wind turbine blade aerodynamics - stall control]]Stall Control:<br>– Passive Stall:<br>Power of the wind turbine is limited by the aerodynamic characteristics<br>of the turbine.<br>– Active stall:<br>Power of the wind turbine is limited additionally by decreasing the pitch<br>angle (increasing the inflow angle ).<br> |
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| | === Pitch<br> === | | === Pitch<br> === |
Revision as of 15:01, 27 August 2011
Wind turbine control concepts
Aerodynamics
Aerodynamics of a wind turbine blade
Stall
Wind turbine blade aerodynamics - stall control
Stall Control:
– Passive Stall:
Power of the wind turbine is limited by the aerodynamic characteristics
of the turbine.
– Active stall:
Power of the wind turbine is limited additionally by decreasing the pitch
angle (increasing the inflow angle ).
Pitch
Aerodynamics at a wind turbine blade during control through pitching
Pitch Control:
– Power of the wind turbine is limited by increasing the pitch angle
(decreasing the inflow angle
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Wind turbine operation
Operation of Fix Speed Wind Turbine (passive stall)
• Start up (with open breaker) if wind speed > cut-in wind speed
• Close breaker
• Operation at constant blade angle over the whole wind speed range
• In case of large wind speeds: Power limited by aerodynamic profile.
Operation of Variable Speed Wind-Turbines
Start up (with open breaker) if wind speed > cut-in wi
Typical power curves of wind turbines.jpg
nd speed
• Close breaker
• Below rated wind-speed
– Maximum power coefficient (Max. Power Tracking)
– Evt: Speed Limitation
• Above rated wind-speed:
– P=Pr
ated (Limited by power electronics converter)
– Pitching
• Advantages of variable speed operation:
– Lower cut-in wind speeds
– Higher efficiency, especially at low wind speeds
– Lower power variations (compared to fixed speed turbines)
• Disadvantage: More expensive!
Generator concepts
Overview Wind generator concepts.jpg
Fixed Speed Induction Generator
Fixed speed induction generator.jpg
Only fix speed operation possible (stall control required)
• Reactive power compensation required
• No reactive power control capability. Additional devices required:
– TSCs (Thyristor switched capacitors)
– STATCOMs
• Risk of dynamic voltage collapse
GTZ Expert Workshop 2010: Grid and System Integration of Wind Energy, 22/23.11.2010, Berlin/Germany
y g p
– > Typically, wind generators based on induction generators are asked to
disconnect in case of voltage dips
Induction Generator with Variable Rotor Resistance
Induction Generator with Variable Rotor Resistance.jpg
Simple concept for variable speed operation.
• Reactive power compensation required.
• No reactive power control capability. Additional devices required:
– TSCs (Thyristor switched capacitors)
– STATCOMs
• Limited LVRT capability. Dynamic voltage collapse problems have to
GTZ Expert Workshop 2010: Grid and System Integration of Wind Energy, 22/23.11.2010, Berlin/Germany
be mitigated by:
– Fast increase of rotor resistance during faults
– Additional reactive power compensation devices (typically TSCs)
Doubly-Fed Induction Generator
Doubly-fed induction generator.jpg
Doubly fed induction generatorf Power flow over- and subsyncronous speed.jpg
Generator with Fully Rated Converter Kopie.jpg
Generator with Fully Rated Converter and direct drive.jpg
Directly Coupled Synchronous Generator with Variable Gear Box
Directly Coupled Synchronous Generator with Variable Gear Box.jpg
