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1.3 WIND TURBINE AND ITS TYPE
Horizontal-axis wind turbines (HAWTs) and vertical-axis wind turbines (VAWTs) are the two types
of wind turbines in which they can be classified into.
Figure 7: Types of wind turbine [16]
Initially, there was a perception that VAWTs are not economically suitable for large-scale electricity
generation. For this reason, HAWTs have been in focus for the last few decades. However, there are
several advantages of VAWTs over HAWTs. First, VAWT does
not require complex yaw-
mechanism. Secondly, VAWTs are omnidirectional and can generate electricity from wind from all
directions.
For these reasons, VAWTs offer energy solutions to remote locations which are
disconnected from main distribution lines. Recently, mass production of VAWTs is started as small-
scale wind turbines to provide electricity for remote locations.
1.4 A BRIEF OVERVIEW OF VAWT
VAWT has several advantages over other wind turbines. It was introduced
by French engineer
Darrieus first in 1931. However, it was not developed until the 1970s because of perception that,
VAWT are not good for electricity generation. VAWTs are independent of wind direction, and have
simplified yaw system. It is less expensive and requires lower maintenance cost. VAWTS are
suitable and a cost-effective option for remote and rural environments.
VAWT are classified into
two major categories: lift-type (Darrieus) turbines and drag-type (Savonius). The Drag-type VAWT
are normally not utilized for generation of electricity applications, because of it low efficiency.
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Mainly, lift-type or Darrieus VAWT are used to generate small scale wind turbines. So, Darrieus
VAWT is focused on in this study.
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