The use of induction generators in wind power applications has been common since the early development of the wind industry. Most of these generators operate at fixed frequency and are connected directly to the utility grid. Unfortunately, this mode of operation limits the rotor speed to a specific rpm. Variable speed operation is preferred in order to facilitate maximum energy capture over a wide range of wind speeds. This paper explores variable speed operating strategies for wind turbine applications. The objectives are to maximize energy production, provide controlled start-up, and reduce torque loading. This paper focuses on optimizing the energy captured by operating at maximum aerodynamic efficiency at any wind speed. The control strategy we analyze uses rotor speed and generator power as the feedback signals. In the normal operating region, rotor speed is used to compute a target power that corresponds to optimum operation. With power as the control objective, the power converter and generator are controlled to track the target power at any rpm. Thus, the torque-speed characteristic of the generator is shaped to optimize the energy capture. The target power is continuously updated at any rpm. In extreme areas of the operating envelope, during start-up, shutdown, generator overload, or overspeed, different strategies driven by other system considerations must be used.
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November 1996
Research Papers
Variable Speed Operation of Generators With Rotor-Speed Feedback in Wind Power Applications
E. Muljadi,
E. Muljadi
National Renewable Energy Laboratory, 1617 Cole Boulevard, Golden, CO 80401
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C. P. Butterfield,
C. P. Butterfield
National Renewable Energy Laboratory, 1617 Cole Boulevard, Golden, CO 80401
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P. Migliore
P. Migliore
National Renewable Energy Laboratory, 1617 Cole Boulevard, Golden, CO 80401
Search for other works by this author on:
E. Muljadi
National Renewable Energy Laboratory, 1617 Cole Boulevard, Golden, CO 80401
C. P. Butterfield
National Renewable Energy Laboratory, 1617 Cole Boulevard, Golden, CO 80401
P. Migliore
National Renewable Energy Laboratory, 1617 Cole Boulevard, Golden, CO 80401
J. Sol. Energy Eng. Nov 1996, 118(4): 270-277 (8 pages)
Published Online: November 1, 1996
Article history
Received:
October 1, 1995
Revised:
June 1, 1996
Online:
February 14, 2008
Citation
Muljadi, E., Butterfield, C. P., and Migliore, P. (November 1, 1996). "Variable Speed Operation of Generators With Rotor-Speed Feedback in Wind Power Applications." ASME. J. Sol. Energy Eng. November 1996; 118(4): 270–277. https://doi.org/10.1115/1.2871793
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