Environmental Engineering Reference
In-Depth Information
Chapter 3
Wind power technology
3.1
Introduction
The main purpose here is to explain the technology in common use for large-scale
wind power generation. The evolution of turbine design is first of all placed in
its historical context. The current design choices facing the industry are then
considered. A simple analysis of the basic process of wind energy extraction is
presented, leading to a discussion of the critical area of power regulation. It will be
seen that the options here depend on whether fixed-speed or variable-speed tech-
nology is adopted.
The description of fixed-speed wind turbine technology includes a review of
relevant induction machine theory. The induction (or asynchronous) machine is a
key component of fixed-speed wind generators, as well as forming the basis for
partial variable-speed designs. This section considers some of the shortcomings of
the fixed-speed designs which dominated the industry's initial growth surge.
The final section of the chapter reviews the arguments that have led to the
growing dominance of variable-speed technology. The section includes a detailed
treatment of partial variable-speed (DFIG) and full variable-speed wind turbine
generator configurations.
3.2
Historical review of wind power technology
The wind has been used as a source of power for pumping water and grinding corn
for more than a thousand years and, by the 18th century, the traditional European
windmill had evolved into a sophisticated device capable of developing up to
25 kW in a strong wind (Golding, 1955). It is estimated that before the industrial
revolution there were some 10,000 windmills in England, but these fell into disuse
with the introduction of reliable steam engines. Water pumping windmills were
used widely in the United States from around 1850 for a hundred years (Spera,
1994), only being superseded by electrical pumps following the extensive rural
electrification programmes of the 1940s.
The success of the 'American' water-pumping windmill stimulated investiga-
tion of how the wind could be used to generate electrical energy. Dr C. F. Brush
built a 17 m diameter, 12 kW DC, multi-bladed wind turbine in Cleveland, Ohio
in 1888, while Prof. P. LaCour conducted important experiments that led to the
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