Yaw drive
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The yaw drive is an important component of the horizontal axis
wind turbine A wind turbine is a device that converts the kinetic energy of wind into electrical energy. Hundreds of thousands of large turbines, in installations known as wind farms, now generate over 650 gigawatts of power, with 60 GW added each yea ...
s'
yaw system Yaw or yaws may refer to: Measurement and technology Movement about the vertical axis * Yaw angle (or yaw rotation), one of the angular degrees of freedom of any stiff body (for example a vehicle), describing rotation about the vertical axis * ...
. To ensure the
wind turbine A wind turbine is a device that converts the kinetic energy of wind into electrical energy. Hundreds of thousands of large turbines, in installations known as wind farms, now generate over 650 gigawatts of power, with 60 GW added each yea ...
is producing the maximal amount of
electric energy Electrical energy is energy related to forces on electrically charged particles and the movement of electrically charged particles (often electrons in wires, but not always). This energy is supplied by the combination of electric current and electr ...
at all times, the yaw drive is used to keep the rotor facing into the wind as the wind direction changes. This only applies for
wind turbine A wind turbine is a device that converts the kinetic energy of wind into electrical energy. Hundreds of thousands of large turbines, in installations known as wind farms, now generate over 650 gigawatts of power, with 60 GW added each yea ...
s with a horizontal axis rotor. The
wind turbine A wind turbine is a device that converts the kinetic energy of wind into electrical energy. Hundreds of thousands of large turbines, in installations known as wind farms, now generate over 650 gigawatts of power, with 60 GW added each yea ...
is said to have a yaw error if the rotor is not aligned to the wind. A yaw error implies that a lower share of the energy in the wind will be running through the rotor area. (The generated energy will be approximately proportional to the cosine of the yaw error).


History

When the
windmills A windmill is a structure that converts wind power into rotational energy using vanes called sails or blades, specifically to mill grain (gristmills), but the term is also extended to windpumps, wind turbines, and other applications, in some par ...
of the 18th century included the feature of rotor orientation via the rotation of the
nacelle A nacelle ( ) is a "streamlined body, sized according to what it contains", such as an engine, fuel, or equipment on an aircraft. When attached by a pylon entirely outside the airframe, it is sometimes called a pod, in which case it is attached ...
, an actuation mechanism able to provide that turning moment was necessary. Initially the
windmills A windmill is a structure that converts wind power into rotational energy using vanes called sails or blades, specifically to mill grain (gristmills), but the term is also extended to windpumps, wind turbines, and other applications, in some par ...
used ropes or chains extending from the nacelle to the ground in order to allow the rotation of the nacelle by means of human or animal power. Another historical innovation was the
fantail Fantails are small insectivorous songbirds of the genus ''Rhipidura'' in the family Rhipiduridae, native to Australasia, Southeast Asia and the Indian subcontinent. Most of the species are about long, specialist aerial feeders, and named as " ...
. This device was actually an auxiliary rotor equipped with plurality of blades and located
downwind Windward () and leeward () are terms used to describe the direction of the wind. Windward is ''upwind'' from the point of reference, i.e. towards the direction from which the wind is coming; leeward is ''downwind'' from the point of reference ...
of the main rotor, behind the
nacelle A nacelle ( ) is a "streamlined body, sized according to what it contains", such as an engine, fuel, or equipment on an aircraft. When attached by a pylon entirely outside the airframe, it is sometimes called a pod, in which case it is attached ...
in a 90° (approximately) orientation to the main rotor sweep plane. In the event of change in wind direction the
fantail Fantails are small insectivorous songbirds of the genus ''Rhipidura'' in the family Rhipiduridae, native to Australasia, Southeast Asia and the Indian subcontinent. Most of the species are about long, specialist aerial feeders, and named as " ...
would rotate thus transmitting its
mechanical power : ''For the physics concept, see .'' Mechanical power is a medical term which is a measure of the amount of energy imparted to a patient by a mechanical ventilator. While in many cases mechanical ventilation is a life-saving or life-preserving in ...
through a
gearbox Propulsion transmission is the mode of transmitting and controlling propulsion power of a machine. The term ''transmission'' properly refers to the whole drivetrain, including clutch, gearbox, prop shaft (for rear-wheel drive vehicles), differe ...
(and via a gear-rim-to- pinion mesh) to the tower of the
windmill A windmill is a structure that converts wind power into rotational energy using vanes called sails or blades, specifically to mill grain (gristmills), but the term is also extended to windpumps, wind turbines, and other applications, in some ...
. The effect of the aforementioned transmission was the rotation of the
nacelle A nacelle ( ) is a "streamlined body, sized according to what it contains", such as an engine, fuel, or equipment on an aircraft. When attached by a pylon entirely outside the airframe, it is sometimes called a pod, in which case it is attached ...
towards the direction of the wind, where the
fantail Fantails are small insectivorous songbirds of the genus ''Rhipidura'' in the family Rhipiduridae, native to Australasia, Southeast Asia and the Indian subcontinent. Most of the species are about long, specialist aerial feeders, and named as " ...
would not face the wind thus stop turning (i.e. the
nacelle A nacelle ( ) is a "streamlined body, sized according to what it contains", such as an engine, fuel, or equipment on an aircraft. When attached by a pylon entirely outside the airframe, it is sometimes called a pod, in which case it is attached ...
would stop to its new position).Wind Power Plants, R. Gasch and J. Twele, Solarpraxis, The modern yaw drives, even though electronically controlled and equipped with large
electric motors An electric motor is an electrical machine that converts electrical energy into mechanical energy. Most electric motors operate through the interaction between the motor's magnetic field and electric current in a wire winding to generate forc ...
and planetary gearboxes have great similarities to the old
windmill A windmill is a structure that converts wind power into rotational energy using vanes called sails or blades, specifically to mill grain (gristmills), but the term is also extended to windpumps, wind turbines, and other applications, in some ...
concept.


Types

The main categories of yaw drives are: * The
Electric Electricity is the set of physical phenomena associated with the presence and motion of matter that has a property of electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as described by ...
Yaw Drives: Commonly used in almost all modern turbines. * The
Hydraulic Hydraulics (from Greek: Υδραυλική) is a technology and applied science using engineering, chemistry, and other sciences involving the mechanical properties and use of liquids. At a very basic level, hydraulics is the liquid counte ...
Yaw Drive: Hardly ever used anymore on modern
wind turbine A wind turbine is a device that converts the kinetic energy of wind into electrical energy. Hundreds of thousands of large turbines, in installations known as wind farms, now generate over 650 gigawatts of power, with 60 GW added each yea ...
s.


Components


Gearbox

The
gearbox Propulsion transmission is the mode of transmitting and controlling propulsion power of a machine. The term ''transmission'' properly refers to the whole drivetrain, including clutch, gearbox, prop shaft (for rear-wheel drive vehicles), differe ...
of the yaw drive is a very crucial component since it is required to handle very large moments while requiring the minimal amount of
maintenance Maintenance may refer to: Biological science * Maintenance of an organism * Maintenance respiration Non-technical maintenance * Alimony, also called ''maintenance'' in British English * Champerty and maintenance, two related legal doct ...
and perform reliably for the whole life-span of the
wind turbine A wind turbine is a device that converts the kinetic energy of wind into electrical energy. Hundreds of thousands of large turbines, in installations known as wind farms, now generate over 650 gigawatts of power, with 60 GW added each yea ...
(approx. 20 years). Most of the yaw drive
gearboxes Propulsion transmission is the mode of transmitting and controlling propulsion power of a machine. The term ''transmission'' properly refers to the whole drivetrain, including clutch, gearbox, prop shaft (for rear-wheel drive vehicles), differe ...
have input to output ratios in the range of 2000:1 in order to produce the enormous turning moments required for the rotation of the
wind turbine A wind turbine is a device that converts the kinetic energy of wind into electrical energy. Hundreds of thousands of large turbines, in installations known as wind farms, now generate over 650 gigawatts of power, with 60 GW added each yea ...
nacelle A nacelle ( ) is a "streamlined body, sized according to what it contains", such as an engine, fuel, or equipment on an aircraft. When attached by a pylon entirely outside the airframe, it is sometimes called a pod, in which case it is attached ...
.


Gear rim and pinions

The gear-rim and the
pinions A pinion is a round gear—usually the smaller of two meshed gears—used in several applications, including drivetrain and rack and pinion systems. Applications Drivetrain Drivetrains usually feature a gear known as the pinion, which may ...
of the yaw drives are the components that finally transmit the turning moment from the yaw drives to the tower in order to turn the
nacelle A nacelle ( ) is a "streamlined body, sized according to what it contains", such as an engine, fuel, or equipment on an aircraft. When attached by a pylon entirely outside the airframe, it is sometimes called a pod, in which case it is attached ...
of the
wind turbine A wind turbine is a device that converts the kinetic energy of wind into electrical energy. Hundreds of thousands of large turbines, in installations known as wind farms, now generate over 650 gigawatts of power, with 60 GW added each yea ...
around the tower axis (z axis). The main characteristics of the gear-rim are its big
diameter In geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints lie on the circle. It can also be defined as the longest chord of the circle. Both definitions are also valid fo ...
(often larger than 2 m) and the orientation of its
teeth A tooth ( : teeth) is a hard, calcified structure found in the jaws (or mouths) of many vertebrates and used to break down food. Some animals, particularly carnivores and omnivores, also use teeth to help with capturing or wounding prey, t ...
. The gear-rims with
teeth A tooth ( : teeth) is a hard, calcified structure found in the jaws (or mouths) of many vertebrates and used to break down food. Some animals, particularly carnivores and omnivores, also use teeth to help with capturing or wounding prey, t ...
on the outer surface have the advantage of higher reduction ratios in combination with the
pinions A pinion is a round gear—usually the smaller of two meshed gears—used in several applications, including drivetrain and rack and pinion systems. Applications Drivetrain Drivetrains usually feature a gear known as the pinion, which may ...
as well as reduced machining costs over the gear-rims with inner
teeth A tooth ( : teeth) is a hard, calcified structure found in the jaws (or mouths) of many vertebrates and used to break down food. Some animals, particularly carnivores and omnivores, also use teeth to help with capturing or wounding prey, t ...
. On the other hand, the former configuration requires the yaw drives to be mounted far apart from each other thus increasing the wind turbine main frame dimensions and costs.


See also

*
Wind turbine A wind turbine is a device that converts the kinetic energy of wind into electrical energy. Hundreds of thousands of large turbines, in installations known as wind farms, now generate over 650 gigawatts of power, with 60 GW added each yea ...
*
Windmill A windmill is a structure that converts wind power into rotational energy using vanes called sails or blades, specifically to mill grain (gristmills), but the term is also extended to windpumps, wind turbines, and other applications, in some ...
*
Yaw bearing The yaw bearing is the most crucial and cost intensive component of a yaw system found on modern horizontal axis wind turbines. The yaw bearing must cope with enormous static and dynamic loads and moments during the wind turbine operation, and ...
*
Yaw system Yaw or yaws may refer to: Measurement and technology Movement about the vertical axis * Yaw angle (or yaw rotation), one of the angular degrees of freedom of any stiff body (for example a vehicle), describing rotation about the vertical axis * ...
*
Wind power Wind power or wind energy is mostly the use of wind turbines to generate electricity. Wind power is a popular, sustainable, renewable energy source that has a much smaller impact on the environment than burning fossil fuels. Historically ...
*
Wind turbine design Wind turbine design is the process of defining the form and configuration of a wind turbine to extract energy from the wind. An installation consists of the systems needed to capture the wind's energy, point the turbine into the wind, convert ...
*
Electric motor An electric motor is an electrical machine that converts electrical energy into mechanical energy. Most electric motors operate through the interaction between the motor's magnetic field and electric current in a wire winding to generate for ...
*
Gearbox Propulsion transmission is the mode of transmitting and controlling propulsion power of a machine. The term ''transmission'' properly refers to the whole drivetrain, including clutch, gearbox, prop shaft (for rear-wheel drive vehicles), differe ...


References


Further reading

* Wind Power Plants, R. Gasch and J. Twele, Solarpraxis, * Wind Energy Handbook, T. Burton
t al. T, or t, is the twentieth letter in the Latin alphabet, used in the modern English alphabet, the alphabets of other western European languages and others worldwide. Its name in English is ''tee'' (pronounced ), plural ''tees''. It is der ...
John Wiley & Sons, Ltd, {{DEFAULTSORT:Yaw Drive Aerodynamics Electric power Electrical generators Electromechanical engineering Energy conversion Wind turbines