PLANT DESIGN AND ENERGY PRODUCTION ESTIMATION - Wind Resource Assessment: A Practical Guide to Developing a Wind Project - page 231

Figure 16-1. Screenshot of the main screen of the openWind wind power plant design and
optimization software. Source: AWS Truepower.

import wind frequency distributions from one or more monitoring towers;

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create or import the results of a wind flow simulation;

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characterize turbines according to a number of parameters including hub height,
rotor diameter, and power output and thrust over a range of speeds;

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place the turbines within the project area;

estimate gross energy production (without losses);

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calculate wake losses and apply other losses to arrive at the net energy production.

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These features constitute the basic elements of an energy production simulation.
Most software packages also have the ability to adjust the turbine positions auto-
matically to maximize the net energy production while meeting certain constraints
(such as respecting property boundaries and setbacks). This process is called optimiza-
tion . It generally involves striking a balance between placing turbines close together
in the windiest locations and spacing them far enough apart to keep wake losses
(and the extra wear and tear caused by wake-induced turbulence) to a minimum.
Although there are exceptions, this usually means, for projects on land, that turbines
are spaced no closer than about 6-10 rotor diameters apart along the most frequent
wind directions and 3-4 rotor diameters apart along the least frequent directions.
Offshore, the spacing is usually larger because wakes tend to persist for a greater
distance.