Page 34 - Wind Energy Handbook

8 INTRODUCTION

based turbines connected to a large electricity network. These turbines are the
subject of this book.
Chapter 2 discusses the wind resource. Particular reference is made to wind
turbulence due to its importance in wind-turbine design. Chapter 3 sets out the basis
of the aerodynamics of horizontal-axis wind turbines while Chapter 4 discusses their
performance. Any wind-turbine design starts with establishing the design loads and
these are discussed in Chapter 5. Chapter 6 sets out the various design options for
horizontal-axis wind turbines with approaches to the design of some of the important
components examined in Chapter 7. The functions of the wind-turbine controller are
discussed in Chapter 8 and some of the possible analysis techniques described. In
Chapter 9 wind farms and the development of wind-energy projects are reviewed
with particular emphasis on environmental impact. Finally, Chapter 10 considers
how wind turbines interact with the electrical power system.
The book attempts to record well-established knowledge that is relevant to wind
turbines, which are currently commercially significant. Thus, it does not discuss a
number of interesting research topics or where wind-turbine technology is still
evolving rapidly. Although they were investigated in considerable detail in the
1980s, vertical-axis wind turbines have not proved to be commercially competitive
and are not currently manufactured in significant numbers. Hence the particular
issues of vertical-axis turbines are not dealt with in this text.
There are presently some two billion people in the world without access to mains
electricity and wind turbines, in conjunction with other generators, e.g., diesel
engines, may in the future be an effective means of providing some of these people
with power. However, autonomous power systems are extremely difficult to design
and operate reliably, particularly in remote areas of the world and with limited
budgets. A small autonomous AC power system has all the technical challenges of
a large national electricity system but, due to the low inertia of the plant, requires a
very fast, sophisticated control system to maintain stable operation. Over the last 20
years there have been a number of attempts to operate autonomous wind–diesel
systems on islands throughout the world but with only limited success. This class
of installation has its own particular problems and again, given the very limited
size of the market at present, this specialist area is not dealt with.
Installation of offshore wind turbines is now commencing. The few offshore wind
farms already installed are in rather shallow waters and resemble land-based wind
farms in many respects using medium sized wind turbines. Very large wind farms
with multi-megawatt turbines located in deeper water, many kilometres offshore,
are now being planned and these will be constructed over the coming years.
However, the technology of offshore wind-energy projects is still evolving at too
rapid a pace for inclusion in this text which attempts to present established engin-
eering practice.

References

CEU, (1997). ‘Energy for the future, renewable sources of energy – White Paper for a
Community Strategy and Action Plan’. COM (97) 559 final.