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All You Need To Know About Wind Turbines - Definition, History, Working Principle, Manufacture Process, Future

Humans have used windmills to capture the force of the wind as mechanical energy for more than 1,300 years. Unlike early windmills, however, modern wind turbines use generators and other components to convert energy from the spinning blades into a smooth flow of AC electricity.
Today we’ll be looking at the definition, history, working principle, manufacturing process, types, as well as futures of wind turbines.

wind energy

 

What is a wind turbine?

A wind turbine is a machine that converts the wind's kinetic energy into rotary mechanical energy, which is then used to do work. In more advanced models, the rotational energy is converted into electricity, the most versatile form of energy, by using a generator.

History of wind turbines

Wind power has been used as long as humans have put sails into the wind. King Hammurabi's Codex already mentioned windmills for generating mechanical energy. Wind-powered machines used to grind grain and pump water, the windmill and wind pump, were developed in what is now Iran, Afghanistan, and Pakistan by the 9th century. 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.

The first windmill used for the production of electric power was built in Scotland in July 1887 by Prof James Blyth of Anderson's College, Glasgow (the precursor of Strathclyde University).Blyth's 10 metres (33 ft) high cloth-sailed wind turbine was installed in the garden of his holiday cottage at Marykirk in Kincardineshire and was used to charge accumulators developed by the Frenchman Camille Alphonse Faure, to power the lighting in the cottage, thus making it the first house in the world to have its electric power supplied by wind power. Blyth offered the surplus electric power to the people of Marykirk for lighting the main street, however, they turned down the offer as they thought electric power was "the work of the devil." Although he later built a wind turbine to supply emergency power to the local Lunatic Asylum, Infirmary, and Dispensary of Montrose, the invention never really caught on as the technology was not considered to be economically viable.

Across the Atlantic, in Cleveland, Ohio, a larger and heavily engineered machine was designed and constructed in the winter of 1887–1888 by Charles F. Brush. This was built by his engineering company at his home and operated from 1886 until 1900. The Brush wind turbine had a rotor 17 metres (56 ft) in diameter and was mounted on an 18 metres (59 ft) tower. Although large by today's standards, the machine was only rated at 12 kW. The connected dynamo was used either to charge a bank of batteries or to operate up to 100 incandescent light bulbs, three arc lamps, and various motors in Brush's laboratory.

With the development of electric power, wind power found new applications in lighting buildings remote from centrally generated power. Throughout the 20th century parallel paths developed small wind stations suitable for farms or residences. The 1973 oil crisis triggered the investigation in Denmark and the United States that led to larger utility-scale wind generators that could be connected to electric power grids for remote use of power. By 2008, the U.S. installed capacity had reached 25.4 gigawatts, and by 2012 the installed capacity was 60 gigawatts. Today, wind-powered generators operate in every size range between tiny stations for battery charging at isolated residences, up to gigawatt-sized offshore wind farms that provide electric power to national electrical networks.

How Do Wind Turbines Work?

Wind turbines produce electricity from wind. Sensors at the top of the turbine measure wind speed and direction to signal to the motor which way to point the nose (so it points towards the wind). The kinetic energy of the wind causes the blades to rotate, which spin a shaft connected to a generator that coverts the kinetic energy to electricity.

Raw Materials
A wind turbine consists of three basic parts: the tower, the nacelle, and the rotor blades. The tower is either a steel lattice tower similar to electrical towers or a steel tubular tower with an inside ladder to the nacelle.

Most towers do not have guys, which are cables used for support, and most are made of steel that has been coated with a zinc alloy for protection, though some are painted instead. The tower of a typical American-made turbine is approximately 80 feet tall and weighs about 19,000 pounds.
The nacelle is a strong, hollow shell that contains the inner workings of the wind turbine. Usually made of fiberglass, the nacelle contains the main drive shaft and the gearbox. It also contains the blade pitch control, a hydraulic system that controls the angle of the blades, and the yaw drive, which controls the position of the turbine relative to the wind. The generator and electronic controls are standard equipment whose main components are steel and copper. A typical nacelle for a current turbine weighs approximately 22,000 pounds.

The most diverse use of materials and the most experimentation with new materials occur with the blades. Although the most dominant material used for the blades in commercial wind turbines is fiberglass with a hollow core, other materials in use include lightweight woods and aluminum. Wooden blades are solid, but most blades consist of a skin surrounding a core that is either hollow or filled with a lightweight substance such as plastic foam or honeycomb, or balsa wood. A typical fiberglass blade is about 15 meters in length and weighs approximately 2,500 pounds.

Wind turbines also include a utility box, which converts the wind energy into electricity and which is located at the base of the tower. Various cables connect the utility box to the nacelle, while others connect the whole turbine to nearby turbines and to a transformer.

How are wind turbines manufactured?

Before consideration can be given to the construction of individual wind turbines, manufacturers must determine a proper area for the siting of wind farms. Winds must be consistent, and their speed must be regularly over 15.5 miles per hour (25 kilometers per hour). If the winds are stronger during certain seasons, it is preferred that they be greatest during periods of maximum electricity use. In California's Altamont Pass, for instance, site of the world's largest wind farm, wind speed peaks in the summer when demand is high. In some areas of New England where wind farms are being considered, winds are strongest in the winter, when the need for heating increases the consumption of electrical power. Wind farms work best in open areas of slightly rolling land surrounded by mountains. These areas are preferred because the wind turbines can be placed on ridges and remain unobstructed by trees and buildings, and the mountains concentrate the airflow, creating a natural wind tunnel of stronger, faster winds. Wind farms must also be placed near utility lines to facilitate the transfer of electricity to the local power plant.

  • Preparing the site
    Wherever a wind farm is to be built, the roads are cut to make way for transporting parts. At each wind turbine location, the land is graded and the pad area is leveled. A concrete foundation is then laid into the ground, followed by the installation of underground cables. These cables connect the wind turbines to each other in series and also connect all of them to the remote control center, where the wind farm is monitored and the electricity is sent to the power company.
  • Erecting the tower
    Although the tower's steel parts are manufactured off-site in a factory, they are usually assembled on-site. The parts are bolted together before erection, and the tower is kept horizontal until placement. A crane lifts the tower into position, all bolts are tightened, and stability is tested upon completion.
  • Nacelle
    The fiberglass nacelle, like the tower, is manufactured off-site in a factory. Unlike the tower, however, it is also put together in the factory. Its inner workings—main drive shaft, gearbox, and blade pitch and yaw controls—are assembled and then mounted onto a base frame. The nacelle is then bolted around the equipment. At the site, the nacelle is lifted onto the completed tower and bolted into place.
  • Rotary blades
    Aluminum blades are created by bolting sheets of aluminum together, while wooden blades are carved to form an aerodynamic propeller similar in cross-section to an airplane wing.
  • By far the greatest number of blades, however, are formed from fiberglass. The manufacture of fiberglass is a painstaking operation. First, a mold that is in two halves like a clam shell, yet shaped like a blade, is prepared. Next, a fiberglass-resin composite mixture is applied to the inner surfaces of the mold, which is then closed. The fiberglass mixture must then dry for several hours; while it does, an air-filled bladder within the mold helps the blade keep its shape. After the fiberglass is dry, the mold is then opened and the bladder is removed. Final preparation of the blade involves cleaning, sanding, sealing the two halves, and painting.
  • The blades are usually bolted onto the nacelle after it has been placed onto the tower. Because assembly is easier to accomplish on the ground, occasionally a three-pronged blade has two blades bolted onto the nacelle before it is lifted, and the third blade is bolted on after the nacelle is in place.
    Installation of control systems
  • The utility box for each wind turbine and the electrical communication system for the wind farm is installed simultaneously with the placement of the nacelle and blades. Cables run from the nacelle to the utility box and from the utility box to the remote control center.

What are the Different Types of Wind Turbines?

Modern wind turbines fall into two main categories:
Horizontal Axis Wind Turbines (HAWT)
Horizontal-axis wind turbines are those most common in the UK. They have three blades and operate "upwind," with the turbine pivoting at the top of the tower so the blades face into the wind.
Vertical Axis Wind Turbines (VAWT)
There are several types of vertical-axis wind turbines (VAWT), including the Darrieus model, where the blades revolve around a vertical shaft.
VAWTs have some advantages. They have fewer components, can be grouped closer together as they can operate in turbulent winds and can catch the wind in any direction - as opposed to HAWT which needs to be pointed into the wind.
However, VAWT’s tend to be less reliable and less efficient so not as well suited to large scale energy production.

The Future and Challenge of Wind Turbines

The future can only get better for wind turbines. The potential for wind energy is largely untapped.

Extreme winds challenge turbine designers. Engineers have to create systems that will start generating energy at relatively low wind speeds and also can survive extremely strong winds. A strong gale contains 1,000 times more power than a light breeze, and engineers don't yet know how to design electrical generators or turbine blades that can efficiently capture such a broad range of input wind power. To be safe, turbines may be overbuilt to withstand winds they will not experience at many sites, driving up costs and material use. One potential solution is the use of long-term weather forecasting and AI to better predict the wind resources at individual locations and inform designs for turbines that suit those sites.

Climate change will bring more incidents of unusual weather, including potential changes in wind patterns. Wind farms may help mitigate some of the harmful effects of climate change. For example, turbines in cold regions are routinely winterized to keep working in icy weather when other systems may fail, and studies have demonstrated that offshore wind farms may reduce the damage caused by hurricanes. A more challenging situation will arise if wind patterns shift significantly. The financing for wind energy projects depends critically on the ability to predict wind resources at specific sites decades into the future. One potential way to mitigate unexpected, climate-change-related losses or gains of wind is to flexibly add and remove groups of smaller turbines, such as vertical-axis wind turbines, within existing large-scale wind farms.

About Openex

Openex is your complete machining and steel fabrication solution — a one-stop shop — for critical wind turbine parts, such as large housings, torque arms, flanges, and more. And we help you seamlessly navigate the entire process from CNC machining and welding to painting and coating.

Components we've manufactured for wind energy:
Rotor hub
Large housing
Gearboxes
Torque arms
Wind power towers
Flanges
Gears
Bearings
Other metal structures.

Contact us at sales3@openex.com.cn or call us at +86 186 5928 0806 for more information about fabrication for your projects and to receive a free project quote today.

About Openex

Openex is home to a full-service, one-stop-shop, contract manufacturing company producing custom large machined parts and fabrications. Our full large fabrication services including large machining, cutting, welding, rolling, punching, braking, testing, painting, and others.
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