The yaw drive is an important component of the horizontal axis wind turbines' yaw system. To ensure the wind turbine is producing the maximal amount of electric energy 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 turbines with a horizontal axis rotor. The wind turbine 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).
When the windmills of the 18th century included the feature of rotor orientation via the rotation of the nacelle, an actuation mechanism able to provide that turning moment was necessary. Initially the windmills 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. This device was actually an auxiliary rotor equipped with plurality of blades and located downwind of the main rotor, behind the nacelle in a 90° (approximately) orientation to the main rotor sweep plane. In the event of change in wind direction the fantail would rotate thus transmitting its mechanical power through a gearbox (and via a gear-rim-to-pinion mesh) to the tower of the windmill. The effect of the aforementioned transmission was the rotation of the nacelle towards the direction of the wind, where the fantail would not face the wind thus stop turning (i.e. the nacelle would stop to its new position). [1]
The modern yaw drives, even though electronically controlled and equipped with large electric motors and planetary gearboxes have great similarities to the old windmill concept.
The main categories of yaw drives are:
The gearbox 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 and perform reliably for the whole life-span of the wind turbine (approx. 20 years). Most of the yaw drive gearboxes 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 nacelle.
The gear-rim and the pinions 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 of the wind turbine around the tower axis (z axis). The main characteristics of the gear-rim are its big diameter (often larger than 2 m) and the orientation of its teeth.
The gear-rims with teeth on the outer surface have the advantage of higher reduction ratios in combination with the pinions as well as reduced machining costs over the gear-rims with inner teeth.
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 parts of the English speaking world. The term wind engine is sometimes used to describe such devices.
A windpump is a type of windmill which is used for pumping water.
A transmission is a mechanical device which uses gears to change the speed or direction of rotation in a mechanical device. Many transmissions have multiple gear ratios, but there are also transmissions that use a single fixed gear ratio.
Yaw or yaws may refer to:
Enercon GmbH is a wind turbine manufacturer based in Aurich, Lower Saxony, Germany. It has been the market leader in Germany since the mid-1990s. Enercon has production facilities in Germany, Brazil, India, Canada, Turkey and Portugal. In June 2010, Enercon announced that they would be setting up Irish headquarters in Tralee.
Turbomachinery, in mechanical engineering, describes machines that transfer energy between a rotor and a fluid, including both turbines and compressors. While a turbine transfers energy from a fluid to a rotor, a compressor transfers energy from a rotor to a fluid.
A reduction drive is a mechanical device to shift rotational speed. A planetary reduction drive is a small scale version using ball bearings in an epicyclic arrangement instead of toothed gears.
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 mechanical rotation into electrical power, and other systems to start, stop, and control the turbine.
Unconventional wind turbines are those that differ significantly from the most common types in use.
Wind power has been used as long as humans have put sails into the wind. For more than two millennia wind-powered machines have ground grain and pumped water. Wind power was widely available and not confined to the banks of fast-flowing streams, or later, requiring sources of fuel. Wind-powered pumps drained the polders of the Netherlands, and in arid regions such as the American mid-west or the Australian outback, wind pumps provided water for livestock and steam engines.
A spiral bevel gear is a bevel gear with helical teeth. The main application of this is in a vehicle differential, where the direction of drive from the drive shaft must be turned 90 degrees to drive the wheels. The helical design produces less vibration and noise than conventional straight-cut or spur-cut gear with straight teeth.
This glossary of mill machinery covers the major pieces of machinery to be found in windmills, watermills and horse mills. It does not cover machinery found in modern factories.
A wind turbine is a device that converts the kinetic energy of wind into electrical energy. As of 2020, hundreds of thousands of large turbines, in installations known as wind farms, were generating over 650 gigawatts of power, with 60 GW added each year. Wind turbines are an increasingly important source of intermittent renewable energy, and are used in many countries to lower energy costs and reduce reliance on fossil fuels. One study claimed that, as of 2009, wind had the "lowest relative greenhouse gas emissions, the least water consumption demands and the most favorable social impacts" compared to photovoltaic, hydro, geothermal, coal and gas energy sources.
The yaw system of wind turbines is the component responsible for the orientation of the wind turbine rotor towards the wind.
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 provide smooth rotation characteristics for the orientation of the nacelle under all weather conditions. It has also to be corrosion and wear resistant and extremely long lasting. It should last for the service life of the wind turbine) while being cost effective.
GE Offshore Wind is a joint venture with Alstom and a subsidiary of GE Renewable Energy, created in 2015 when most of that company's other electrical power and generation assets were acquired. GE's stake in the joint venture is 50 % plus 1 share.
Starting in 1975, NASA managed a program for the United States Department of Energy and the United States Department of Interior to develop utility-scale wind turbines for electric power, in response to the increase in oil prices. A number of the world's largest wind turbines were developed and tested under this pioneering program. The program was an attempt to leap well beyond the then-current state of the art of wind turbine generators, and developed a number of technologies later adopted by the wind turbine industry. The development of the commercial industry however was delayed by a significant decrease in competing energy prices during the 1980s.
Seawind Ocean Technology B.V., a Netherlands based company, is a manufacturer (OEM) of integrated floating wind turbine and green hydrogen systems. Seawind is developing two-bladed floating wind turbines suitable for installation in all seas, including hurricane regions and ultra-deep waters. Founded on original research and development work by NASA, Hamilton Standard, Enel, and Aeritalia; Seawind's offshore wind power turbines with integrated foundations have been patented, proven at 1.5 MW, and achieved Type D DNV certification in December 2019. The company is now planning the launch of its Seawind 6 demonstrator to be followed by the pre-series Seawind 12, a project earmarked for installation as early as 2024-25 that seeks to obtain DNV's highest certification level.
The Gamma 60 wind turbine, a 1.5 MW two-bladed upwind horizontal axis wind turbine, was installed by Wind Energy Systems Taranto S.p.A. (WEST) at Alta Nurra, Sardinia, Italy in April 1992. Founded on original research and development work by NASA and Hamilton Standard, the Gamma 60 wind turbine was the world's first variable speed wind turbine with a teetering hinge.
A vertical-axis wind turbine (VAWT) is a type of wind turbine where the main rotor shaft is set transverse to the wind while the main components are located at the base of the turbine. This arrangement allows the generator and gearbox to be located close to the ground, facilitating service and repair. VAWTs do not need to be pointed into the wind, which removes the need for wind-sensing and orientation mechanisms. Major drawbacks for the early designs included the significant torque ripple during each revolution, and the large bending moments on the blades. Later designs addressed the torque ripple by sweeping the blades helically. Savonius vertical-axis wind turbines (VAWT) are not widespread, but their simplicity and better performance in disturbed flow-fields, compared to small horizontal-axis wind turbines (HAWT) make them a good alternative for distributed generation devices in an urban environment.