Wind power is a natural part of Sweden's energy supply and could play an important part in the conversion of the energy system.

Today's expansion is becoming more frequent by setting up new wind farms. In order to maximize the return there is a strive to achieve high energy production combined with low costs for maintenance and repairs. This can be achieved in particular by optimizing the turbines positions in relation to each other within the wind farm. The purpose of this master’s thesis is, with focus on Lillgrund wind farm to study the significance that the distance between wind turbines, the layout of the park and the tower heights has on energy production, the farm efficiency and each individual wind turbine. An economic assessment for some of these configurations will also be made.

The goals for this work are to;

1)            Design and simulate Lillgrund wind farm. Simulate with different wake models to investigate the differences between the wake models and see which one provides results of an energy production most consistent with the available production data for Lillgrund wind farm.

2)            Examine how the individual wind turbine energy production is affected when the number of wind turbines in the same area is reduced and the distances increased.

3)            Investigate how much the energy production and farm efficiency differs when the wind farm area expands. Also making an economic assessment of costs for this park expansion.

4)            Study the wind farm’s energy production and farm efficiency when the turbine height is modified.

5)            Simulating cases where a row of wind turbines in the farm is removed and how this affects the energy production for individual turbines aswell as the entire farm and its efficiency.

The results show that N.O. Jensen is the wake model that provides an energy production closest to that of Lillgrund. While the number of turbines are reduced on Lillgrunds area, the individual wind turbine energy production increases To simulate the park with the original number of wind turbines on a larger area, thus with larger column and line distances resulted in both cases in an increased energy production and farm efficiency. The results show that the estimated costs of cables will be twice as large in the second case in which both row and column spacing is increased in comparison to the first case where only the row spacing increased. Even when comparing the increase in energy production, the results show that the second case has twice the increase of the first case.

In the case where the height was modified in the wind farm, the results show that both the energy production and farm efficiency increased. 376 GWh of energy production when the whole park was elevated to 85 m of height, and 355 GWh where half the park was elevated, costing 35 million SEK or 17 million SEK for the steel of the towers. Results from the case where different rows in the park are removed, show in all cases an increase in farm efficiency and an average production for the individual wind turbine, but it also shows a reduction in farm production.

The action that increases the farm efficiency and energy production the most is to expand both the row and column spacing in Lillgrund. The row and column spacing affected the energy production and farm efficiency equally. To elevate the farm to a hub height of 85 meters is an expensive investment that will not yield much greater energy production or higher farm efficiency. The row that reduces Lillgrund wind farms efficiency and individual turbines energy production the most is row 3.