How Wind Turbines Really Work: The Hidden Secrets

sponsored by bright why are there three blades? why they are so high why they are so slow and how it generates electricity grab a notebook and a piece of paper to take notes and take a sip from your engineering-minded mug let's find out that this basic

wind

turbine can power a small LED, this one larger It may power a small house, but these mega

turbines

can power entire cities. A

wind

turbine simply converts the kinetic energy of the wind into mechanical energy and that is converted into electrical energy. We can feel the energy of the wind in our On the other hand, we know that you can turn a windmill, we can turn it into motion like this strange thing that walks powered by the wind or we can connect a generator to it and it will produce electricity, try it yourself, take a simple DC motor, turn the shaft and you will see.

Notice that it produces a voltage, so simply attach a blade to it and it will spin with the wind and generate electricity. The wind speed increases the higher we go and it is also less turbulent the larger the blades the more wind energy we can capture large blades. Large

turbines

are difficult to transport, so we often find the largest turbines at sea, where space is not an issue, although it is much cheaper. and are easier to install on land, but they punctuate the landscape, cast long flickering shadows, and can also create some noise. Wind turbines need a strong, deep foundation.

We can extend to the bottom of the sea, but some waters are so deep that it is easier to just float the wind turbines on a platform, you may notice that the smaller wind turbines have a towel fin on the back, but the large ones do not. . I will explain why later in the video the wind turbine needs to face the wind and the wind changes direction. We could use a vertical wind turbine and it will

work

in any direction of the wind. There are many designs, but they are generally less efficient in comparison and do not scale very well.

The wind turbine can be downwind or downwind. Against the wind it is more efficient because the wind hits the blades before the tower and then the cell, but the blades must be stronger so that they do not bend in the wind and hit the tower. How do you feel about wind turbines? Would you live next to one? Tell me in the comment. In the section below, when we look at a large wind turbine, we notice that the tubular Ste tower rises from the ground, we see that it reduces its diameter as it reaches the top, it rises towards the sky to reach the strongest wind inside of the tower. we have an access ladder for engineers, there are some power cables and we often find a transformer at the base at the top of the tower, we find a large bearing and a ring gear attached to this bearing is the base plate and this is the main support.

A set of Y motors is bolted to the base plate and its gears lock with the large bearing gear. This will control the direction of the turbine. A small encoder counts how much the turbine has turned. I will explain this part later in the video. You will also find a set of hydraulic brakes and a large disc brake that will keep the turbine in position. At the back of the base we find the electric generator. Generally there will be an electrical and control panel. Here also the generator is connected to a gearbox through the high speed shaft attached to the shaft is a hydraulically controlled disc brake, it will be driven from the hydraulic control assembly, the gearbox is then connected to the main shaft of low speed, it is supported by the main bearing and connects to the hub at the Very forward of the turbine turbine, the blades will be bolted to the hub through some gear bearings.

The metal hub is covered with a nose cone to protect it and also improve the aerodynamics inside the hub. Normally we find three motors that are attached to the hub and their gears are locked with the gear bearings, this allows the blades to tilt, the base plate and all the main components are covered with a fiberglass casing and this forms The cell, the box protects the components from winds, sun, rain, etc. At the top of the Nel we find a wind vein that will determine the direction of the wind and there is also an anemometer to measure the wind speed.

The wind direction will determine the direction of the wind and the controller releases the brakes, allowing the motors to rotate the cell into alignment. with the wind, once aligned the brakes are reapplied, the wind flows over the blades forcing them to rotate, this rotates. The hub that rotates the shaft, the shaft rotates slowly but with high torque, the bearing supports it and allows low friction rotation, the shaft will rotate. the gears in the transmission and then the output shaft connects to the rotor of the electric generator the rotor rotates and induces a voltage generating electricity we will see this in detail in a moment the output of the generator flows through a cable and down the tower to the Transformer where it will be sent to the electrical grid and distributed to towns and homes.

Other energy generators, such as solar or nuclear, will also be injected into the grid. You can also watch our video on how solar panels

really

work

. Wind and solar energy are a great combination. of renewable energy because it is always sunny or windy the blades are generally made of reinforced fiberglass, which makes them very strong and very light, allowing them to be longer so that we can capture more wind energy, metal blades or wood are expensive and heavy. and are more likely to fail heavy blades are difficult to turn and are also more difficult to stop the blades will have an aerodynamic shape the shape changes along the blade and is often twisted along its length to improve aerodynamic efficiency wind turbines Smaller ones generally have a fixed angle blade, but large turbines can change the angle of the blade.

The front part of the arrow blade is known as the leading edge. The rear part is called the trailing edge. The line between these two points is the chord line When the blade is tilted, the difference between the chord line and the relative direction of the wind is known as the angle of attack, the blade will obstruct the path of the wind, forcing it to go under and over . The arrow blade air is a fluid and when an object passes through the fluid we get friction across the surface of the object and we also get resistance from the shape of the object.

We call these forces Dr drag and they act parallel to the wind, which slows the blade down. The arrow blade is designed to minimize drag forces and maximize air lift. It will have to travel a longer distance over the top due to the curved profile, meaning the speed has to increase at the top and may decrease at the bottom, causing the two streams to arrive at different times as As air speed increases, pressure decreases. therefore, a region of lower pressure develops at the top and a region of higher pressure develops along the bottom. The higher pressure side naturally pushes the blade toward the lower pressure region creating some of the lifting force.

We also have air hitting the bottom of the blade providing a force. The air at the top and bottom is diverted downward. This downward momentum creates an equal and opposite upward force and this helps push the blade towards the region of lower pressure, which also increases the lifting force. The tip of the blade has a higher speed through. the incoming wind stream than the shaft, so the lift and drag will be different, the shape of the blade is twisted to try to account for this and improve the angle of attack, we tilt the entire blade to alter the amount of Lift produced as the angle of attack increases, more lift is generated, but at a certain point the currents will separate and become turbulent, this reduces lift and increases drag, slowing down rotation.

We can see with this wind turbine model that if the flames are perpendicular to the wind, then the maximum drag occurs without lift, so the blades do not rotate and therefore no voltage is generated, but there is a lot of force in the tower, if the blades are parallel to the wind, then very little lift is generated, the rotation is slow and only a small one. Voltage is generated, it is also very easy to stop this rotation, but if we tilt the blades to an optimal angle we generate a large amount of lift, the hub rotates very fast and therefore we generate a few volts, the design of the blades will have an optimal angle of attack and we can find that from the design table we can see that with this DC generator, the faster the Sha spins, the more voltage is generated, but if it has been too fast for too long, it gets very hot and eventually will be destroyed.

Our generator might be rated for, say, 2 megaw, so we have to tilt the blades to control how fast they spin and that controls how much power we generate and that helps us stay below the maximum rating of the generator, the wind turbine It will not start until a minimum. wind speed is reached, this is the cut in speed, the wind speed increases and the power output also increases at a certain wind speed, the wind turbine will tilt its blades to stop generating power and the brakes will be applied to protect the wind turbine. Known as shear speed, the anemometer measures the wind speed and the controller changes the angle of the blades.

So how many shovels do we need? Each of the blades will generate lift, which will cause rotation, but will also generate drag, which will slow down the blades with this model. wind turbine we can change the number of blades to find out that with one blade it is very slow the structure is also very unstable it does not produce much voltage and it is very easy to stop also it did not start automatically so this is not a Very good design with two blades, we noticed that it turns on automatically, is much more stable and can produce a much higher voltage.

With three blades, it produces only a slightly higher voltage, but it's now much harder to stop because it picks up so much more wind. power with four blades, again produces a slightly higher voltage, but with five blades the voltage has started to drop slightly and with six blades again this produces an even lower voltage, but it is very difficult to stop it, so all three versions of Four and five blades produce the three blade version is the most energy consuming and very stable and also costs the lease to build so this is the obvious choice. Two blades are also common on medium-sized turbines and that is because they are cheap and quite stable.

Micro wind turbines can have many blades and that is because they are installed lower, they experience slower and weaker wind speeds. Large wind turbines spin quite slowly. The blades are very long, so the tip of the blade travels much faster than the hub. At a certain point the tip of the blade will travel so fast that it will break the sound barrier, this will create a sonic boom and forces will begin to tear the blades apart even at low speeds, there are large centrifugal forces acting on the blades. Additionally, the generator needs to spin at a certain speed to produce 50 or 60 hertz electricity, which will be supplied to our homes.

The gearbox increases the speed so the rotor does not need to spin very fast to achieve this. Small wind turbines They have a large fin that allows them to align their blades with the wind without deflecting the wind, so the wind energy will reach the cell and tower first, which is less efficient. Vertical wind turbines don't need your system, they will work in any direction of the wind, but large wind turbines don't use talin and that's because it would have to be so ridiculously big to work and that will add a lot of moving weight. They also swing in turbulent winds, which generates a lot of uncontrolled force on the structure, bearings and blades, so engineers chose to use a wind vein that indicates the direction of the wind and then a computer controls some motors that will rotate the base plates around the large gear on the tower to change the direction of the cell so that it always faces into the wind for optimal performance.

Then some brakes will hold the turbine. In position, once the cell is aligned with the wind, a small encoder tracks the rotation of the cell in large turbines, this is because the power cables must be connected from the generator to the tower, if it rotates too much it will twist. the cables and eventually breaks them frequently, then the cell will rotate with the wind, but shortly after the wind direction will change again and then the cell rotates to realign with this and undoes the twist, the cables are suspended to reduce the twist and the computer controls how far the cell can rotate to avoid twisting them,It will stop and turn in the opposite direction if necessary.

Small turbines only use slip rings to avoid that, but large turbines produce much more power, making it cheaper, safer and easier to use just one cable and track the rotations. Small wind turbines are usually direct drive. They often use permanent magnet generators like this one. Large wind turbines spin much slower, so we use gears to increase the speed of the rotor to produce enough power and frequency output in the generator. Three stage gearbox consisting of one set of planetary gears and then two straight stages the input shaft is low speed but high torque the gearbox converts it to high speed low torque the rotation speed is controlled by the pitch of the blades, so the input speed can be just 18 RPM and the output speed is 1800 RPM.

We need to reach this speed to control the output of the generator. We also have a hydraulic disc brake at the rear of the gearbox because the shaft has low torque, so it is easier to stop the blades first. It is used to stop rotation, the brakes will hold it in place, for example during maintenance, double fed induction generator is the most common generator for large wind turbines, smaller home wind turbines could use a three phase motor brushless like this one or they could just use a brushed DC generator like this one. Small DIY wind turbines can use a basic DC motor when we pass DC current through a coil of wire an electromagnetic field is produced but when we pass AC current through the coil a magnetic field is produced which changes the polarity the rate of changedepends on the frequency of the alternating current applied to the coil a basic generator has a magnet in the center of the rotor and a coil of wire in the stator when the rotor rotates the magnetic field interacts with the electrons in the wire pushing them forward and then pulling them back as the magnet rotates, this will create an alternating current with a sine wave that repeats each time the north and south poles of the magnet rotate past the coil.

The electrical outlets in our homes provide 50 or 60 hertz, that is, the sine wave. It is repeated 50 or 60 times per second to achieve that the magnet would need to rotate thousands of times per second but if we add another magnet and a coil we can reduce the distance and the time it takes for the north and south poles to pass a coil and thus the speed of rotation is reduced to only 1,800 RPM, the gearbox increases the speed about 100 times, so we only need 18 RPM of the hub to achieve the fire. We can see with this simple bipolar AC generator that the frequency produced depends on the rotation speed. rotor shaft speed in the wind turbine the rotor connects to the blades the faster the wind the faster the shaft rotates, although we have some control over the speed Sha by turning the blades to change the amount of lift or drag that occurs if the wind speed is too fast the turbine shuts down and that is our cut off speed, a generator spins quite easily and will produce voltage but when we connect a load to the generator it is much harder to spin, this will add load mechanical to the blades and will decelerate.

Lower them so that the wind turbine does not start until a minimum wind speed occurs and that is the cut-off speed. The doubly fed induction generator consists of a rotor that is attached to the high-speed output shaft of the gearbox. The rotor has three sets of coils. attached to it, these connect to some slip rings at the end, the stator surrounds the rotor, this also has three sets of coils inside when the blades rotate, the Sha rotates and the rotor rotates, but the stator remains stationary, the rot is connected to a three-phase system. Electrical supply through the collector rings.

Each coil produces an alternating magnetic field at slightly different times depending on the AC frequency being applied. These are placed around the rotor so that they combine and create an equivalent rotating electromagnetic field. The direction of rotation depends on the phase synchronization, a controller determines the frequency and also the direction of the rotating electromagnetic field. As the electromagnetic field rotates it induces a voltage in the stator coils and this generates an alternating current which we then export to the grid if we apply a We supply 60 HZ to the rotor, then we generate and export 60 HZ back to the grid because the wind controls the speed of the rotor.

It could spin at 1,800 RPM, but it could also spin slower than that or it could spin faster than the magnetic field. is rotating and is attached to the shaft that is also rotating, so they will combine if the rotor speed drops to, say, 1600 RPM, which is equivalent to 5333 Hertz, so we would need a frequency of 6.67 hertz at the rotor coils to compensate for the difference and achieve At 60 hertz the speeds will combine and that will produce a rotating magnetic field equivalent to 60 hertz which produces 60 hertz in the stator if the shaft speed is increased to perhaps 2000 RPM which is equivalent to 66.67 Hertz and that's too fast, so we need to subtract 6.67 Hertz and we get that by rotating the electromagnetic field in the opposite direction to the rotor, if the rotor had exactly the required 1800 RPM, then we need zero Hertz, which is DC electricity, so we apply a constant current to the rotor and the The magnetic field rotates only with the shaft at the same speed as the shaft, so we get 60 HZ in the rotor and 60 HZ in the stator.

The controller constantly makes adjustments to the rotor current frequency to ensure that a 60 HZ output is maintained. The engineering design of a wind turbine is complex, but with our brilliant sponsor you can learn the basics of engineering. They have many amazing courses and even a 30-day free trial so you can learn about electricity, magnetism, planetary gears, mathematics, Python programming, and even data analysis. all the key skills you need to become a brilliant engineer, the courses provide hands-on interaction with problem solving and regular progress monitoring, which I found made learning fun and easy to visualise, they even have an app for learning in person on the progress.

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