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Added Turbulence and Optimal Power Distribution in Large Off-Shore Wind Farms

Clevenhult, Thomas Alexander and Himmelman, Fredrik (2010) In MSc Theses
Department of Automatic Control
Abstract
Wind power is subject to intensive research in the development of using more renewable energy. With a growing number of countries aiming at reducing carbon dioxide emissions, increasing investments are being made in wind turbines and wind farms. An intriguing option is to build large wind farms at sea. There are many challenges with building large offshore wind farms. This Master's thesis addresses the challenge of the wind turbines interacting with each other within the farm. Observations and measurement data indicate that wind turbines standing in rows behind other turbines experience a lower mean wind speed and a higher level of turbulence. With the wind turbines controlled individually, this means that upwind turbines will produce more... (More)
Wind power is subject to intensive research in the development of using more renewable energy. With a growing number of countries aiming at reducing carbon dioxide emissions, increasing investments are being made in wind turbines and wind farms. An intriguing option is to build large wind farms at sea. There are many challenges with building large offshore wind farms. This Master's thesis addresses the challenge of the wind turbines interacting with each other within the farm. Observations and measurement data indicate that wind turbines standing in rows behind other turbines experience a lower mean wind speed and a higher level of turbulence. With the wind turbines controlled individually, this means that upwind turbines will produce more power than downwind turbines, and downwind turbines will be subject to a higher degree of fatigue than the upwind turbines, as a result of the higher level of turbulence. The starting point of the thesis is the proposition that controlling the wind turbines in the farm as a team, taking the interaction with the other turbines into account, forms an optimization problem of finding power references to each turbine, such that total power output of the farm is maximized and the total fatigue is minimized. The ambition is to present a way of formulating the optimization problem and finding the optimal power references, in order to investigate if this proposition is plausible. A model for the added turbulence induced by turbines upwind from other turbines is presented, along with a model for the wind deficit. These models are then used to formulate the optimization problem, which is solved using a gradient descent algorithm. Our results indicate that there is a potential benefit in controlling wind turbines in a farm with respect to the other turbines. By including the wind deficit and added wake turbulence in determining the power references, we have found that the total power output could be increased while at the same time reducing the total amount of turbulence experienced by the turbines. (Less)
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author
Clevenhult, Thomas Alexander and Himmelman, Fredrik
supervisor
organization
year
type
H3 - Professional qualifications (4 Years - )
subject
publication/series
MSc Theses
report number
TFRT-5867
ISSN
0280-5316
language
English
id
8847492
date added to LUP
2016-03-16 12:29:47
date last changed
2016-03-16 12:29:47
@misc{8847492,
  abstract     = {Wind power is subject to intensive research in the development of using more renewable energy. With a growing number of countries aiming at reducing carbon dioxide emissions, increasing investments are being made in wind turbines and wind farms. An intriguing option is to build large wind farms at sea. There are many challenges with building large offshore wind farms. This Master's thesis addresses the challenge of the wind turbines interacting with each other within the farm. Observations and measurement data indicate that wind turbines standing in rows behind other turbines experience a lower mean wind speed and a higher level of turbulence. With the wind turbines controlled individually, this means that upwind turbines will produce more power than downwind turbines, and downwind turbines will be subject to a higher degree of fatigue than the upwind turbines, as a result of the higher level of turbulence. The starting point of the thesis is the proposition that controlling the wind turbines in the farm as a team, taking the interaction with the other turbines into account, forms an optimization problem of finding power references to each turbine, such that total power output of the farm is maximized and the total fatigue is minimized. The ambition is to present a way of formulating the optimization problem and finding the optimal power references, in order to investigate if this proposition is plausible. A model for the added turbulence induced by turbines upwind from other turbines is presented, along with a model for the wind deficit. These models are then used to formulate the optimization problem, which is solved using a gradient descent algorithm. Our results indicate that there is a potential benefit in controlling wind turbines in a farm with respect to the other turbines. By including the wind deficit and added wake turbulence in determining the power references, we have found that the total power output could be increased while at the same time reducing the total amount of turbulence experienced by the turbines.},
  author       = {Clevenhult, Thomas Alexander and Himmelman, Fredrik},
  issn         = {0280-5316},
  language     = {eng},
  note         = {Student Paper},
  series       = {MSc Theses},
  title        = {Added Turbulence and Optimal Power Distribution in Large Off-Shore Wind Farms},
  year         = {2010},
}