What is Wind Turbine?
A wind turbine, or alternatively known as a wind power converter, is a mechanism that converts the kinetic energy of the wind in electrical energy. The blades of a wind turbine difference between 13 and 20 spins per minute, at their method, at a constant or variable velocity, where the rotor velocity changes to reach varying efficiency with respect to the wind velocity.
Wind turbines have an average life measure of over 25 years, although the largest accounting criteria are set for a period of 20 years. The rapid development of wind technology has increased the stability of wind turbines.
- What is Wind Turbine?
- History of Wind Turbine
- How Do Wind Turbine Work?
- Components of Wind Turbine
- Types of Wind Turbine
- Important facts about wind turbine
History of Wind Turbine
In the first century Heron of Alexandria, a Greek engineer, and mathematician, made the earliest accounts of using a wind wheel.
William Cubitt was an English engineer and inventor who invented the self-regulating windmill sail in the early 1800s.
Daniel Halladay “the father of the American windmill” invented the self-regulated windpump in 1854. His version seen in Argentina, South Africa, and New Zealand.
In 1887 Professor James Balth of Scotland built the first textile sail wind turbine for electricity generation. This generated enough electricity to illuminate their house.
Charles F. Brush in Cleveland Ohio built the first large-scale wind turbine in America in 1888 with a gearbox.
In 1890s, Paul La Court a Danish inventor and scientist studied the aerodynamics of windmills and methods of storing electrical energy in batteries. He invented a regulator to produce a stable power supply
William Heronmess “the father of modern wind energy” and inventor of wind turbine arrays, wind ships, wind furnaces, and offshore flotilla ideas – in the late 1960s, he correctly predicted the future energy crisis and had a vision on a grand scale. Renewable Energy Development.
Vestas and Siemens Wind Energy are Danish manufacturers that supply a substantial share of wind turbines worldwide.
How does a wind turbine work?
Wind turbines operate on a simple principle: fan-like wind turbines use the wind to create electricity, rather than using electricity to produce electricity. The wind rotates the propeller-like blade of a turbine around the rotor, which rotates a generator, generating electricity.
The wind is a form of solar energy due to a combination of three concurrent events:
- The sun is heating the atmosphere unevenly
- Irregularity of the surface of the earth
- Earth revolves.
Wind flow patterns and activities vary considerably over the United States and are adjust by bodies of difference in water, flora, and localities. Man utilizes this airflow, or movement energy, for various destinations: generating electricity sailing, and flying kites.
The terms “wind power” and “wind energy” both describe the process by which wind use to generate mechanical power or electricity. This mechanical power can implement for a specific task or a generator can convert this electricity from mechanical power.
When air passes from the blade, the air pressure on one side of the blade reduces. The difference in air pressure on either side of the blade generates both lift and drag. The force of the lift is more effective than that of drag and this makes the rotor spin. The rotor connects to the generator, both if it is a direct drive turbine or through a shaft and a series of a gearbox that speeds up a rotation and allows for physically smaller generators. This translation of the aerodynamic energy to the rotation of a generator creates electricity.
Components of Wind Turbine
How do wind turbines produce energy? The functioning of the wind turbine can explained in the following steps:
1) Automatic orientation
The wind turbine is automatically located to take maximum advantage of the kinetic energy of the wind, from the data recorded by Vane and the anemometer connected at the top. The Naxalite revolves around a top located at the end of the tower.
2) Turning to the blade
The wind bends the blade, which begins moving with a wind speed of about 3.5 m / s and produces maximum power with a wind speed of 11 m / s. With really heavy winds (25 m / s), the blades fanned and the wind turbines slow down to limit excessive voltages.
The rotor (a unit of three blades installed in the hub) bends a slow axis that attaches to a gearbox that lifts a turn velocity of 13 to 1,500 revolutions per minute.
The gearbox conveys its energy within a fast axis that connected to the generator, which generates electricity.
The created energy moves from inside the tower to the bottom. From there, the energy moves from an underground line to the substation, where its voltage increase to inject into the electrical grid and it is issue to the points of consumption.
In this section, all important functions of the wind turbine are control and manage by substations and control centers to detect and fix any disturbances.
Types of Wind Turbine Generator
There are mainly 4 types of wind turbine generators that can be recognized for different wind turbine systems, they are:
- Direct current (DC) generator
- Alternating current (AC) synchronous generator
- AC asynchronous generator, and
- Switched Reluctance Generator.
Each of those generators can operate at fixed or unsteady speeds. Due to the active nature of wind power, it is ideal for working wind turbine generators at variable speeds.
Operating a generator at Different speeds reduces the physical stresses on the turbine blades and drives, and which increases the efficiency and torque transient behavior of the aerodynamic system.
1) Dc generator
A DC wind generator method consists of a DC generator, a wind turbine, an insulated gate bipolar transistor a transformer, an inverter, a controller, and a power grid. For shunt-wound DC generators, the field current increases with operating speed, while the balance between the wind turbine drive torque determines the actual speed of the wind turbine.
The power removes through a brush, which joins the commentator that use to turn the generator AC power to the DC output. These generators require regular maintenance and are comparatively expensive due to utilizing commutators and brushes. The use of DC wind turbine generators is different in wind turbine purposes except in situations of low power demand.
2) AC synchronous generator
AC synchronous wind turbine generators can use continuous or DC excitation from strong magnets or electromagnets. This is why they name both “electrically excited synchronous generators ” and “permanent magnet synchronous generators”.
When the wind turbine drives the rotor, three-phase power creates in the stator windings that attache to the grid through transformers and power converters. In the state of fixed-speed synchronous generators, the rotor velocity must be at exactly synchronous speed. Or, synchronization will be lost.
When using fixed-speed synchronous generators, irregular fluctuations of wind-speed and periodic disorders are due to the tower-shedding effect. In addition, synchronous wind turbine generators have a smaller impact, so that they do not allow the drive to train consumers to be electrically absorbed.
When synchronous wind turbine generators integrate into the power grid, a delicate operation required by synchronizing their frequency with the grid. Besides, these generators are more complex, costly, and prone to collapse than induction generators. During the last decades, PM generators have applied in wind turbine applications due to their high-power density and low mass.
The structure of the PM generator is relatively simple. Rugged PMs are installing on the rotor to generate a constant magnetic field, and the power production is collect from the stator utilizing a slip ring, commutator, or brush.
PMs are sometimes integrating into a cylindrical mold aluminum rotor to decrease costs. The basic principle of operation of PM generator is related to the synchronous generator except that PM generator can be operated asynchronously. Some of the advantages of permanent magnet synchronous generators are the removal of commutators, slip rings, and brushes so that the machines are strong, stable, and manageable.
Due to the variability of actual wind speeds, permanent magnet synchronous generators cannot produce electricity with a set frequency. For this, the generator must connect to the power grid through correcting AC-DC-AC by power converters.
This means that the generated AC power with unsteady frequency and magnitude is first corrected to a fixed DC, and then converted back to AC power. In addition, these sturdy magnet machines can be useful for direct-drive applications, in which case, they can relieve the troubles, gearboxes that cause failures for the majority of wind turbines.
One of the potential alternatives of synchronous generators is a high-temperature superconducting generator. Superconductor generators have parts such as stator back iron, stator copper winding, rotor cooling system, HTS field coils, rotor core, rotor support structure, and others.
The superconducting coil can about 10 times greater than the current resistance and conductor losses compared to conventional copper wires. In extension, all field circuits using superconductors can limit power loss. In addition, an improvement in current density allows for higher magnetic fields, which will result in a larger scale and a significant reduction in size for wind turbine generators.
Therefore, superconducting generators may have higher capacities and weight reduction possibilities and may be preferable for wind turbines of 10 MW or more. Nearly in 2005, Siemens introduced the first superconducting wind turbine generator into the world, a 4MW synchronous generator.
With high capacity, synchronous generators can encounter many technical difficulties, especially for low-maintenance, long-life, wind turbine systems. Such a challenge is, for example, restoring operation and cooling the system after a technical impediment.
3) AC Asynchronous Generators
When the common method of power generation utilizes synchronous generators. Advanced wind power systems use induction machines, frequently in wind turbine applications. Induction generators are classified into two types. Double-fed induction generators with wound rotors and fixed-speed induction generators with squirrel-cage rotors.
Generally, induction generators are easy, dependable, cheap, and excellently designed. These generators have a high degree of damping and can absorb rotor speed fluctuations and drive train customers. In the case of a constant speed induction generator, the stator connects to the grid via a transformer, and the rotor connects to the wind turbine via a gearbox.
By 1998, most wind turbine companies began fixed-speed electricity generators of 1.5 MW and below. These generators were normally operating for a 50 Hz utility grid at 1500 revolutions per minute (rpm), along with a three-phase gearbox.
Squirrel cage induction generators can use in variable speed wind turbines, as used in controlling synchronous machines. In such cases, the output voltage cannot control, and external supply of reactive power required. This indicates that fixed-speed induction generators are outlawed when it comes to working only in a small range of discrete speeds.
Other disadvantages of these generators are machine low efficiency, size, noise, and safety.
These days, more than 85% of installs wind turbines use dubbed-fed induction generators, and the largest capacity for commercial wind turbine product is increase capacity for 5MW. The increased capacity provides several advantages including high energy yield, low mechanical stress, power fluctuations, and controllability of reactive power.
Induction generators also suffer from voltage instability. Additionally, the soaking impact can cause power loss in the rotor. There is no direct control over concluding voltage, nor constant lapse currents. In these cases, it is possible to regulate the speed and torque of a doubly-fed induction generator by controlling the rotor side converter.
In sub-synchronous operation, the rotor-side converter acts as an inverter and the grid-side converter as a rectifier. On the other hand, in the case of super-synchronous operation, the rotor side converter acts as a rectifier and the grid-side converter as an inverter.
4) Switched Reluctance Wind Turbine Generator
The switched qualm wind turbine generator has a strong rotor and stator-like features. The objection of magnetic circuits connecting stator and rotor changes with rotor winding. This, in change, induces currents in the winding at the stator.
The reluctance rotor is made of laminate steel sheets and has no electric field winding or permanent magnets.
For this reason, the reluctance generator is simple, easy to perform, and join. Another noticeable feature of these generators is their high dependability. This is because they can operate in hard or huge-temperature environments.
Because the reluctance torque is only a fraction of the electrical torque, the rotor of a switched reluctance generator. It is usually larger for a given rate of torque than the other with electrical excitations.
When reluctance generators combined with direct drive equipment, the machines are significantly bigger and more complex, making them less valuable in wind power applications.
Types of Wind Turbine
Wind turbines can rotate about either a horizontal or a vertical axis, the former being both older and more common. They can also include blades, or be bladeless. Vertical designs produce less power and are less common. There are main Two Types of Wind turbine:
- Horizontal Axis Wind Turbines
- Vertical Axis Wind Turbine
1) Horizontal Axis Wind Turbines
Horizontal axis wind turbines are a common style most of us think about when we think of wind turbines. A horizontal axis wind turbine is a design related to a windmill, it has blades that seem like a propeller that rotates on the horizontal axis.
The horizontal axis wind turbine consists of the central rotor shaft and electric generator. At the tip of a tower and must show in the wind. Smaller turbines indicated by an easy wind vane square with a rotor (blade). While larger turbines typically use a wind sensor coupled with a servo motor to turn the turbine into the air. Since a tower creates turbulence behind it, the turbine is usually pointing upstream of the tower. The wind turbine blades hardened to prevent them from the push into the tower by strong winds. Additionally, the blades located a considerable distance in front of the tower and are sometimes slop to a small extent.
Downward machines are built despite the turbulence problem, as additional mechanisms. That is not required to keep them in line with the wind. Additionally, blades may be permitted to bend in powerful winds which reduces their running area and thus their wind resistance. Since turbulence leads to fatigue failures, and reliability is so important, most horizontal axis wind turbines are inverted machines.
Advantages and disadvantages of horizontal axis wind turbines
Advantages of a horizontal axis wind turbine
- The tall tower base allows strong wind access in sites with wind shears. In some wind shear sites, wind speeds can increase by 20% every ten meters and power output by 34%.
- High efficiency, since the blades always move vertically for air, gaining power through the entire winding. Indifference, all vertical axis wind turbines, and most difficult airborne wind turbine devices involve a wide variety of communications, requiring part of the cycle to rear the airfoil surfaces opposite the wind. The back against the air naturally leads to lower efficiency.
Disadvantages of a horizontal axis wind turbine
- Giant tower construction is required to support heavy blades, gearboxes, and generators.
- The components (gearbox, rotor shaft, and brake assembly) of a horizontal axis wind turbine are lifted into position.
- Their height gives them noticeable over large areas, disturbing the landscape’s features and sometimes creating local opposition.
- The downward variant suffers from fatigue and structural collapse when a blade passes through the winding darkness of the tower.
- The horizontal axis wind turbine needs an additional yaw control mechanism to convert the blade.
- Horizontal spindle wind turbines usually require a braking or yawing device in high winds to prevent the turbine from spinning and destroying or self-harming.
- Cyclic tautness and shake When the turbine turns to face the wind, the rotating blades work like a gyroscope. As it pivots, the gyroscopic precession attempts to bend the turbine forward or backward into the corset. For every blade on the wind generator’s turbine, the force is lowest when the blade is horizontal and greatest when the blade is vertical. This cyclic twisting can quickly fatigue and crack the blade roots, hub, and axle of the turbine.
2) Vertical axis wind turbine
In vertical axis wind turbines, the main rotor shafts are arranged vertically. The major benefit of this arrangement is that the wind turbine does not need to be pointed in the wind. This is an improvement at sites where the wind direction is highly variable or there are violent winds.
Along a vertical axis, generators and other primary components can be placed near the ground. So the tower does not need to support it, also making maintenance easier. The main drawback of a vertical axis wind turbine is that it usually creates drag when moving in the wind.
Vertical-axis turbines are difficult to mount on towers, meaning they are often installed near the base. On which they rest, such as the ground or the roof of a building. Wind speeds are slower at low altitudes, so less wind power is available for a given size turbine. Airflow near the spot and different objects can produce turbulent flow. That can include vibration problems including noise and bearing wear that can enhance maintenance or reduce its service life. However, when the turbine is mounted on the roof, the building usually redirects air to the roof, doubling the wind speed on the turbine. If the height of the roof-mounted turbine tower is about 50% of the building height. It is near-optimal for maximum wind power and minimum wind turbulence.
Types of vertical-axis wind turbines
- Darius wind turbine
- Savonius Wind Turbine
1) Darius wind turbine
The “Agbutter” turbine, or Darius turbine, was named after the French inventor, Georges Darius. They have good efficiency but produce large torque ripples and cyclic stresses on the tower, which contributes to poor reliability. They typically require some external power source, or an additional Savonius rotor to initiate turning, as the starting torque is very low. Torque ripple is minimized using three or more blades, resulting in greater solubility of the rotor. Density is measured by the blade area divided by the rotor area. The new Darius type turbines are not held by male-wires but have an external superstructure. That is connected to the top bearing.
2) Giromill Wind turbine
A subtype of Darius turbine with straight, as opposed to curved, blades. The cycle turbine variation has a variable pitch to reduce torque beats and is self-starting. The advantages of unsteady pitch are high rising torque; A broad, almost flat torque curve; A high coefficient of production; more efficient operation in turbulent winds; And a lower blade speed ratio that reduces the bending of the blade. Straight, V or curved blades may be used.
3) Savonius Wind Turbine
These are drag-type devices with two (or more) scoops used in anemometers, flattener vents (typically seen on the bus and van roofs), and in some high-reliability low-efficiency power turbines. They are always self-starting if there are at least three scoops.
The twisted Savonius is a modified savory, with long helical scoops to provide smooth torque. It is often used as a roof-mounted wind turbine and has even been adapted for ships.
4) Parallel Wind Turbine
A parallel turbine is similar to a crossflow fan or centrifugal fan. It uses ground effect. This type of vertical axis turbines has been tried for years. The unit producing 10 kW was built by Israeli wind forecaster Bruce Brill in the 1980s.
Advantages and Disadvantages of Vertical Axis Wind Turbines
Advantages of Vertical Axis Wind Turbines
- They can generate electricity in every wind direction.
- Strong auxiliary towers are not required because the generator, gearbox, and other components are grounded.
- Lower production costs than horizontal axis wind turbines.
- As there is no need to be efficient to point the turbine in the wind direction therefore yaw drive and pitch mechanism are not required.
- Easy installation compared to another wind turbine.
- Easy to move from one place to another.
- Low maintenance cost.
- They can be installed in urban areas.
- There is less risk for humans and birds as the blades move at relatively low speeds.
- They are particularly suitable for areas with extreme weather conditions, such as in mountains where they can supply the electricity in mountain huts.
Disadvantages of Vertical Axis Wind Turbines
- As only one blade of a wind turbine works at a time, the efficiency is much lower than that of a horizontal axis wind turbine.
- They require an initial push to start; This initial push that the spinning starts on its own to form the blade must be initiated by a small motor.
- When they are much less efficient than horizontal axis wind turbines, they are pulled extra when their blades rotate.
- They have relatively high vibrations, as airflow near the ground creates turbulent flow.
- Due to vibration, there is an increase in bearing wear resulting in an increase in maintenance costs.
- They can cause noise pollution.
- Vertical axis wind turbines may require male wires to hold it (man wires are impractical and heavy in field areas).
Important facts about wind turbine
There have been various improvements in wind turbine technology after the first wind turbine was built in 1887 in Scotland. The first in America held Charles F. Brush in 1887 in Cleveland Ohio. It was considered a mountain. And it had a rotor diameter of 17 meters and had 144 rotor blades made of cedar. It had a capacity of 12kW and lasted 20 years. The presence and operation of wind turbines today are quite different.
- A gigawatt wind power plant is about the same output as a new large natural gas plant.
- A wind turbine has around 8000 components.
- The average capacity of the wind turbine is 1.9 MW.
- The average height of the hub is 82.7 m.
- The average rotor diameter is 99.4 m.
- Fiberglass with a hollow core is the most common material used to make blades. Wooden blades are solid. Other blades have a skin that is either hollow or filled with a lightweight material such as plastic foam or honeycomb or balsa wood.
- Three-bladed wind turbines have a better balance than two blades. Some wind turbines have the appearance of an oval animal.
- The latest version of windmills do not have rotor blades, but they are thinly inverted cone-shaped, almost like the sky joint ‘in front of the sky’.
- Designers always design long turbines with long blades. This is because more energy is produced when air is exposed to the greater surface area of the blade.
- The biggest wind turbine is in Geldorff, Germany. It is 178 meters long and has a blade length of 68.5 meters. It is a part of a quartet of turbines expected to produce an average of 10500 MW / h. every year.
How do wind turbines work when it not windy?
If there is too little wind and the blades are moving too slowly, the wind turbine no longer produces electricity. The turbine starts to create power at what is known as the cut-in speed. Power output continues to grow as the wind speed increases, but at a slower rate than it does right after the cut-in point.
How long does it take a wind turbine to pay for itself?
Writing in the International Journal of Sustainable Manufacturing, they conclude that in terms of cumulative energy payback, or the time to produce the amount of energy required of production and installation, a wind turbine with a working life of 20 years will offer a net benefit within five to eight months of being.
Can wind turbines be placed anywhere?
In order for wind turbines to be economically viable, they need to be installed in a place where they will produce enough electricity. Wind farms are best suited for coastal areas, the tops of hills, and open planes essentially anywhere with strong, reliable wind.
Are wind turbines worth it?
Despite the high initial cost, however, well-placed wind turbines particularly those in exposed coastal areas and which receive an average wind speed of above 6m/s can generate a significant amount of energy and therefore present an excellent return on investment.
Do wind turbines really kill birds?
Wind Turbines Kill Birds. This Incredibly Simple Trick Has Saved Them. A study finds painting windmill blades reduced bird fatalities by over 70 percent. Scientists are always looking for ways to reduce bird deaths from turbines.