Page 184 - Fluid Power Engineering

Advanced W ind Resource Assessment 157

Wind resource map at a detailed level of granularity, a 50 m x

50 m granularity is recommended for wind farm layout. This
resource map specifies the mean wind speed in each 50 m x
50 m cell.
Turbine details like rated power, tower height, rotor diameter,

and others
Wind farm details like desired size of wind farm in terms of

megawatt and type of layout (regular grid versus random).
Constraints of the wind farm. There will be several site-

specific constraints, a few examples are presented below:
Boundary of the wind farm

Outline of roads, transmission lines, microwave paths,

water bodies, residential/office/industrial/recreational
areas, and other features that require a setback
Setback distances from each marked feature. In some ar-

eas, local wind ordinances specify the setback distances
from different features. For instance, setback from property
boundary may be 1.25H; setback from roads, transmission
lines, and water bodies may be 1.5H; inhabited areas may
be 500 m, where H is the total height = tower height +
blade radius. The setback conditions are discussed in more
detail in Chapter 11.
An elliptical exclusion zone around a turbine. The ellipse is

defined using distances between turbines perpendicular to
and parallel to the predominant direction of wind. To speed
up the layout optimization, these constraints are specified
so that the algorithm treats the elliptical region around the
center of a turbine as an exclusion zone for placing other
turbines. As mentioned in the wake section, 9D and 3D are
guidelines for the major and minor radius of the ellipse.
Exclusion areas because of environmental constraints like

noise, shadow flicker, visual impact, wetlands, wildlife,
and others.
Exclusion areas because of flight safety and interference

with long-range radars
Wind resource assessment applications, like WindPRO and
WindFarmer, have implemented tools to specify the constraints and
compute an optimal layout using discrete optimization methods. A
general optimization problem of this type will have multiple local
maxima and the challenge is to find the global maximum or an ac-
ceptable local maxima. An optimization of large 100+ MW wind farm
may take a few hours to run. The results include a layout of turbines,