Electricity Generation Using Wind Power

The following sections are included:

• Foreword and Acknowledgements for the Second Edition
• Foreword and Acknowledgement for the First Edition
• About the Authors
• Contents

The following sections are included:

• Nature and Origin of the Wind
  • Atmospheric pressure
  • The Coriolis effect
• Development of Wind Converters
• References

The following sections are included:

• Power and Energy Basis of Wind Converters
  • Origin and properties of the wind
  • Power and energy
• Theoretical Power Available in the Wind
• Theoretical Maximum Power Extractable from the Wind
• Practical Power Extractable from the Wind
  • Power coefficient
  • Torque versus rotational speed
  • Shaft power versus rotational speed
  • Tip-speed ratio (TSR) and torque coefficient (C_τ)
• Mechanical and Aeronautical Features of Wind Machines
  • Aeronautical forces on the turbine rotor blades
  • Axial thrust (pressure)
  • The “Yaw” effect
  • Gyroscopic forces and vibrations
  • Centrifugal forces
  • Solidity factor
  • Two rotor blades or three rotor blades?
  • Shaft torque and power
• Fixed Rotational Speed or Variable Rotational Speed?
  • Constant speed operation
  • Variable speed operation
• Efficiency Considerations of Wind-Powered Electricity Generation
• Worked Numerical Examples on Wind-Turbine Operation
• Problems and Review Questions
• References

The following sections are included:

• Nineteenth-Century Windmills
• Early Twentieth-Century Wind-Energy Turbines
• Later Twentieth-Century Wind-Energy Turbinest
• Modern Large Wind Power Installations
• Worked Numerical Example
• Vertical Axis Wind Machines
  • The Savonius design
  • The Darrieus design
  • Other forms of vertical axis machine
• References

The following sections are included:

• The Availability of Wind Supply
  • Global survey
  • Energy content of the wind
  • Wind-energy supply in Europe
  • Wind-energy supply in the USA
• Statistical Representation of Wind Speed
• Choice of Wind Turbine Sites
  • Identification of suitable areas
  • Selection of possible sites within the chosen area
• Effects of the Site Terrain
• Spacing Effects of Wind Farm Arrays
• Problems and Review Questions
• References

In most electrical power systems, the bulk of the power is supplied by rotating machine generators. These can be of many types, but those used for windpower generation are mainly the following:

• direct current (DC) machines,
• alternating current (AC) synchronous machines, and
• induction machines.

The following sections are included:

• Types of Semiconductor Switching Converters
• Three-Phase Controlled Bridge Rectifier
• Three-Phase Controlled Bridge Inverter Feeding an Infinite Bus
  • Output voltage
  • Real power output
  • Reactive power
  • RMS output current
  • Inverter power factor
• The Effect of A.C. System Reactance on Inverter Operation
• Three-Phase Cycloconverter Feeding an Infinite Bus
• Matrix Converter Feeding an Infinite Bus
• Worked Numerical Examples
  • Three-phase bridge rectifier
  • Three-phase bridge inverter feeding on infinite bus
• Problems and Review Questions
  • Three-phase controlled bridge rectifier, with ideal supply, feeding a highly inductive load
  • Three-phase, full-wave, and controlled bridge inverter feeding an infinite bus
• References

Wind power generator systems convert energy from the wind into electrical energy. They must operate as effectively as possible whilst providing safety to the entire system construction and requiring least maintenance cost. These can be achieved by adequate design and construction of the entire turbinegenerator system, especially for small systems with only stall control and an induction generator connected directly to the grid. For most other types of turbine-generator systems it is important to employ properly designed controllers for regulating power and speed.

The wind blows intermittently. Irregularity of the wind is reflected into an irregular supply of energy from wind generators. This means that no electricity supply can rely wholly on wind generation but requires backup from a regular and reliable source…

The British Wind Energy Association (BWEA) has issued a set of best practice guidelines, including environmental features, of wind turbine and wind farm operation. Other countries operate corresponding systems and these also normally take the form of voluntary advice rather than legislated prescriptions. The BWEA guidelines topics are summarised in Table 9.1, with comments in a separate column. Some environmental features listed in the table are discussed in greater detail in further sub-sections of this chapter.

In order to be economically worthwhile, the income produced from a windgenerated electricity plan has to exceed the total cost of installing and operating the plant. The manufacturing and selling of electricity is the same, economically, as any other business. Both the “income” and “expenditure” sides of the balance sheet involve the detailed consideration of several important variables and features that are discussed in appropriate sections below.

The following sections are included:

• Answers to the End of Chapter Problems
• Index