Environmental Engineering Reference
In-Depth Information
Chapter 12
Site Assessment and Installation
12.1 Introduction
This chapter considers some of the main aspects of turbine installation: site
assessment, optimal tower height, and the loads during erection and lowering
which are part of Load Case J of the IEC simple load model. Installation loads are
similar to those for transmission structures which are covered by IEEE Std
951-1996. Some brief comments are made on foundations for which a very useful
reference is the IEEE Std 691-2001 on transmission structure foundation design
and testing.
Site assessment normally involves mapping the wind resource and choosing the
best locations for the turbine(s). For large wind farms, anemometer masts up to
50 m high are often used. Monitoring for periods up to 1 year or longer is followed
by sophisticated modeling of power production and optimal layout of the individual
turbines, e.g. Kusiak and Song [
1
]. A similar assessment may be prohibitively
expensive for a single small turbine so it could be installed without detailed
knowledge of the wind resource. If the turbine is the only source of power (or shares
that role with PV) then resource assessment may be irrelevant. Nevertheless,
neglecting site assessment, or doing it poorly, has often resulted in under-per-
forming turbines, e.g. Encraft [
2
]. One important aspect of site assessment is
selecting the best tower height. Tower costs obviously rise with increasing height as
shown by Fig.
10.9
and many manufacturers offer a range of heights, so there will
be an optimal height that provides, say, the cheapest electricity per unit capital cost.
The management and cost of installation can often be a major component of a
wind turbine project, particularly if there are difficult site features, like reclaimed
ground that requires extensive foundations, or a large distance from the turbine to
its load. It is not possible to give general guidelines, apart from noting that once
the turbine and tower loads—the total mass (vertical load), horizontal force, and
base overturning moment—are known, then the design of the tower foundation is
no different in principle from any other foundation. (Only lattice towers can
possibly cause significant torsional loads on the foundations.) Determination of
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