Ingenieur Vol. 75 ingenieur July 2018-FA | Page 36

INGENIEUR
types). Horizontal-axis wind turbines typically have
three blades, are sited upwind and operate with
the blades facing into the wind. Wind turbines
can be built on land or offshore in large bodies of
water like oceans and lakes, depending on the site
wind quality.
Wind Resource Assessment
Figure 3: Horizontal-axis (HAWT) Wind Turbine
(Source: Turbineinfo, 2011)
Figure 4: Darrieus Wind Turbine (VAWT)
(Source: REUK, 2018)
Figure 5: Savonius Wind Turbine(VAWT)
(Source: coolmyplanet.org, 2017)
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The initial and important step for wind energy
exploitation is determining the potential or
the feasibility of wind power development, is
completing a wind resource assessment (WRA).
In addition, WRAs are also used to map the wind
resource potential for a region or a country.
Therefore, it is crucial to have a nationwide WRA
in any particular country or region. WRAs can be
categorized in three basic stages: (i) preliminary
area identification, (ii) area wind resource
evaluation, and (iii) micrositing. These are briefly
explained below:
(i) Preliminary area identification
Existing meteorological wind data is used to
establish a mesoscale wind map (Figure 6) using
spatial modelling, where the modelling consists
of analysing wind flow over complex terrains in
order to understand the physical processes. Wind
power density maps (Figure 7) are established to
estimate wind resources which are expressed in
wind power classes ranging from Class 1 to Class
7 (Table 1).
Wind maps and information about wind
resource characteristics are useful in identifying
potential areas for wind-energy applications. After
process screens have been conducted over a
relatively large region (e.g. state or utility service
territory) for suitable wind resource areas, new
wind measurement sites can be selected.
(ii) Area Wind Resource Evaluation (Wind
measurement campaign)
Area wind resource evaluations are compiled using
the International Electrotechnical Commission
(IEC) IEC 1400-1 and IEC 61400-1. Sampling
intervals to obtain wind data vary with an average
of ten minutes; these temporal intervals are
sufficient enough to determine the local breeze
data. Wind sensors (Figure 8) are installed at