How Wind Turbines Really Work: The Hidden Secrets

sponsored by brilliant why are there three blades why are they so high why are they so slow and how does it even generate electricity grab a pad and paper to make notes and sip from your engineering mindset mug let's find out this basic wind turbine can power a small LED this larger one can power a small home but these Mega turbines can power entire towns a wind turbine simply converts the kinetic energy of of the wind into mechanical energy and that is converted into electrical energy we can feel the energy of the Wind on our hand we know that it can turn a windmill we can turn that into motion like this strange wind powerered walking thing or we can attach a generator to it and it will produce electricity try it yourself take a simple DC motor spin the shaft and you'll notice it produces a voltage so just attach a blade to it and it will spin in the wind and generate electricity the speed of the wind increases the higher we go and it's also less turbulent the larger the blades the more wind energy we can capture large blades need to be higher off of the ground but the speed of the wind is the largest influencer in power generation large turbines are difficult to transport so we often find the largest turbines out at Sea where space isn't a problem although it is a lot cheaper and easier to install them on land but they do Mark the landscape they cast long flickering shadows and they can also create Some Noise the wind turbines need a deep strong Foundation we can extend down into the seabed but some waters are so deep it's easier to just float the wind turbines on a platform you might notice that smaller wind turbines have a towel fin at the back but large ones don't I'll explain why later in the video video the wind turbine needs to face the wind and the wind changes direction we could use a vertical wind turbine and that will work in any wind direction there are many designs but they are usually less efficient in comparison and they don't scale up very well the wind turbine can be upwind or downwind upwind is more efficient because the wind hits the blades before the tower and then the cell but the blades need to be stronger so that they don't 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 section down below when we look at a large wind turbine we notice the Ste tubular Tower rising up out of the ground we see it reduces in diameter as it reaches the top it rises high up into the sky to reach the strongest wind inside the tower we have an access ladder for engineers there's some power cables and we often find a Transformer at the the base on the top of the tower we find a large bearing and a ring gear attached to this bearing is the bed plate and this is the main support a set of Y Motors are bolted onto the bed plate and their gears into lock with the large bearing gear this will control the direction of the turbine a small encoder counts how far the turbine has rotated I'll explain this part later on in the video we also find a set of hydraulic brakes and a large disc brake which will hold the turbine in position at the back of the bed plate we find the electrical generator there will usually be an electrical and a controls panel here too the generator connects to a gearbox via the high-speed shaft attached to the shaft is a disc brake which is hydraulically controlled this will be powered from the hydraulic control set the gearbox then connects to the main low speed shaft this is supported by the main bearing this connects to the Hub at the very front of the tur turbine the blades will then bolt onto the Hub via some geared bearings the metal Hub is covered with a nose cone to protect it and also improve the aerodynamics inside the Hub we typically find three motors these are attached to the hub and their gears into lock with the geared bearings this allows the blades to be tilted the bed plate and all the main components are covered with a fiberglass housing and this forms the the cell the case protects the components from the winds the Sun the rain Etc on the top of the Nel we find a wind vein which will determine the wind direction and there's also an anemometer to measure the wind speed the wind vein will determine the wind direction and the controller releases the brakes this allows the motors to turn the the cell to align it with the wind once aligned the brakes are reapplied the wind flows over the blades forcing them to rotate this rotates The Hub which rotates the shaft the shaft rotates slowly but with high torque the bearing supports this and allows the low friction rotation the shaft will rotate the gears in the transmission and then the output shaft connects onto the electrical generator's rotor the rotor turns and induces a voltage generating electricity we will see this in detail in just 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 the towns and houses other power generators such as solar or nuclear will also feed into the grid you can also see our video on how solar panels actually work wind and solar are a great combination of renewable energy because it's always either sunny or windy the blades are typically made from reinforced glass fiber which makes them very strong and very lightweight that allows them to be longer so we can capture more wind energy metal or wooden blades are expensive they're heavy and they're more likely to fail heavy blades are hard to turn and they're also harder to stop the blades will have an aerofoil shape to them the shape changes along the length of the blade and often twists along the length to improve the aerodynamic efficiency smaller wind turbines usually have a fixed angle blade but large turbines can change the angle of the blade the front of the aerrow foil is known as the Leading Edge the rear is called called the trailing Edge the line between these two points is the cord line when the blade tilts the difference between the cord line and the relative wind direction 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 foil air is a fluid and when an object passes through fluid we get friction across the object's surface and also get resistance from the shape of the object we call these forces Dr drag and they act parallel to the wind slowing the blade down the arrow foil is designed to minimize drag forces and maximize lift the air will have a longer distance to travel over the top due to the curved profile that means the speed has to increase along the top and it can slow down along the bottom resulting in the two streams arriving at different times as the air speed increases the pressure decreases therefore a lower pressure region develops over the top and a higher pressure region along the bottom the higher pressure side naturally pushes the blade into the lower pressure region creating some of the lifting Force we also have air colliding with the underside of the blade providing a force the air on the top and the bottom are being deflected downwards this downwards momentum creates an equal and opposite upward force and this helps push the blade into the lower pressure region also adding to to the lifting Force the tip of the blade has a higher velocity through the incoming Windstream than the Hub so the lift and the drag will be different the shape of the blade is Twisted to try and 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 streams will separate and become turbulent this reduces the lift and increases the drag which slows the rotation down we can see with this model wind turbine that if the blaze are perpendicular to the wind then the maximum drag occurs with no lift and so the blades do not turn and therefore no voltage is generated but there's a lot of force on the tower if the blades are parallel to the wind then very little lift is generated the rotation is slow and only a small voltage is generated it's also very easy to stop this rotation but if if we tilt the blades to an optimal angle we generate a large amount of lift the Hub spins very fast and so we generate a few volts the blades design will have an optimal angle of attack and we can find that on the design chart we can see with this DC generator the faster the Sha rotates The More Voltage is generated but if it beens too fast for too long it becomes very hot and it will eventually destroy itself our generator might be rated for say 2 megaw so we have to tilt the blades to control how fast the blades rotate and that controls how much power we generate and that helps us to stay under the maximum rating of the generator the wind turbine won't 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 will be applied to protect the wind turbine this is known as the cutout speed the anemometer measures the wind speed and the controller changes the angle of the blades so how many blades do we need the blades will each generate lift which causes rotation but they also generate drag which will slow the blades down using this model wind turbine we can change the number of blades to find out with one blade it's very slow the structure is also very unstable it doesn't produce much voltage and it's very easy to stop plus it didn't self-start so this is not a very good design with two blades we notice that it will self-start it's much more stable and it can produce a much higher voltage with three blades it produces only a slightly higher voltage but it is now much harder to stop because it's catching much more wind energy with four blades it again produces a slightly high higher voltage but with five blades the voltage has started to drop slightly and at six blades again this produces an even lower voltage but it is very hard to stop so the three four and five blade versions produce the most energy the three-blade version is very stable and it also costs the lease to build so this is the obvious choice two blades is also common in mediumsized turbines and that's because it's cheap and fairly stable micro wind turbines might have many blades and that's because they are installed lower so that they experience slower and weaker wind speeds large wind turbines rotate quite slowly the blades are very long so the tip of the blade is traveling much faster than the Hub at a certain point the blade tip will travel so fast they will break the sound barrier this creates a sonic boom and the forces will start to rip the blades apart even at low speeds there's large centrifugal forces acting on the blades Additionally the generator needs to rotate 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 doesn't need to rotate very fast to achieve this small wind turbines have a large taal finin which allows them to align their blades into the wind without this they will turn away from the wind and so the wind energy will hit them the cell and the tower first Which is less efficient vertical wind turbines do not need a your system they will work in any wind direction but large wind turbines don't use a talin and that's because they would need to be so ridiculously large to work and that's going to add a lot of moving weight they also swing in turbulent winds which is a lot of uncontrolled force on the structure the bearings and the blades so Engineers instead opted to use a wind vein which indicates the direction of the wind and a computer then controls some motors which will rotate the bed plates around the large gear on the tower to change the direction of the cell so that it always faces the wind for Optimal Performance some brakes will then hold the turbine in position once the the cell is aligned with the wind a small encoder tracks the rotation of the the cell in large turbines that's because the power cables need to connect from the generator down into the tower if it rotates too far it will twist the cables and eventually snap them often then the cell will turn in the wind but a short time later the wind direction will change back and so then the cell turns to realign with this and undoes the twist the cables are suspended to reduce the twisting and the computer controls how far th the cell can turn to avoid twisting them it will stop and rotate in the opposite direction if needed small turbines just use slip rings to avoid that but large turbines produce a lot more power making it cheaper safer and easier to just use a cable and track the rotations small wind turbines are typically direct drive they often use permanent magnet generators like this one large wind turbines turn much slower so we use gears to increase the speed of the rotor to produce sufficient power and output frequency at the generator typically we find a three stage gearbox consisting of a planetary gear set and then two spur stages the input shaft is low speed but high torque the gearbox converts this into highp speed low torque the rotational speed is controlled by the pitch of the blades so the input speed might be just 18 RPM and the output speed is 1,800 RPM we need to achieve this speed to control the output of the generator we also have a hydraulic disc brake at the back of the gearbox because the shaft is low torque so it's easier to stop the blades are first used used to stop the rotation the brakes will then hold it in place for example during maintenance the doubly fed induction generator is the most common generator for large wind turbines smaller domestic wind turbines might use a three-phase brushless motor like this one or they might just use a brush DC generator like this one tiny DIY wind turbines can just use a basic DC motor when we pass DC current through a coil of wire it produces an electromagnetic field but when we pass AC current through the coil it produces a magnetic field that changes polarity the rate of change depends on the frequency of the AC current applied to the coil a basic generator has a magnet at the center of the rotor and a coil of wire on the stator when the rotor rotates the magnetic field interacts with the electrons in the wire pushing them forwards and then pulling them backwards as the magnet rotates this will create an alternating current with a sine wave which repeats every time the North and South Pole of the magnet rotates past the coil the electrical outlets in our homes provide either 50 or 60 hertz meaning the sine wave repeats 50 or 60 times per second to achieve that the magnet would need to rotate thousands of times a second but if we add another magnet and coil we can reduce the distance and time taken for the North and South Pole to pass a coil and so the rotational speed reduces to just 1,800 RPM the gearbox increases the speed by around 100 times so we only need 18 RPM of the hub for the blaze to achieve that we can see with this simple two- pole AC generator that the frequency produced depends on the rotational speed of the rotor shaft in the wind turbine the rotor connects to the blades the faster the wind the faster the shaft rotates although we do have some control over the Sha speed by rotating the blades to change the amount of lift or drag which is produced if the wind speed is too fast the turbine shuts down and that is our cutout speed a generator rotates quite easily and it will produce a voltage but when we connect a load to the generator it's much harder to rotate this will add mechanical load to the blades slowing them down so the wind turbine won't start until a minimum wind speed occurs and that is the cut in speed the doubly fed induction generator consists of a rotor which is attached to the highspeed output shaft from the gearbox the rotor has three sets of coils attached to it these connect onto some slip rings at the end the stator surrounds the rotor this also has three sets of coils inside when the blades turn the Sha turns and the rotor rotates but the stator remains stationary the rot is connected to a three-phase electrical supply via the slip Rings each coil produces an alternating magnetic field at slightly different times based on the AC frequency which is applied these are positioned around the rotor so that they combine and create an equivalent rotating electromagnetic field the direction of the rotation depends on the timing of the phases a controller determines the frequency and also the direction of the rotating electromagnetic field as the electromagnetic field rotates it induces a voltage into the coils of the stator and this generates an AC current which we then export to the grid if we apply a 60 HZ supply to the rotor then we generate and Export 60 HZ back to the grid because the wind is controlling the rotor speed it might rotate at 1,800 RPM but it might also rotate slower than that or it might rotate rotate faster than that the magnetic field is rotating and that is attached to the shaft which is also rotating so these will combine if the rotor speed drops to say 1,600 RPM that's equivalent to 5333 Hertz so we would need a 6.67 hertz frequency on the rotor coils to make up the difference and achieve the 60 hertz the speeds will combine and that will produce an equivalent 60 Herz Herz rotating magnetic field which produces 60 HZ at the stator if the speed of the shaft increases to maybe 2,000 RPM that's equivalent to 66.67 Hertz and that is much too fast so we need to subtract 6.67 Hertz and we achieve that by rotating the electromagnetic field in the opposite direction to the rotor if the rotor was exactly the required 1,800 RPM then we require zero Hertz which is DC electricity so we apply a constant current to the rotor and the magnetic field rotates only with the shaft at the same speed as the shaft and so we get 60 HZ on the rotor and 60 HZ of the stator the controller is constantly making adjustments to the frequency of the rotor current to ensure a 60 HZ output is maintained the engineering design of a wind turbine is complex but with brilliant our sponsor you can learn core engineering principles they have so 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 that you need to become a brilliant engineer the courses provide Hands-On interaction with problem solving and regular progress monitoring which which I found made learning fun and easy to visualize they even have an app for on the-go learning personally I've enjoyed their algorithm 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Channel: The Engineering Mindset

Views: 493,262

Keywords: wind turbine, betz's limit, offshore wind, wind turbine for home, wind energy, renewable energy, electricity, electrical engineering, wind farm, betz limit, renewable, wind sensors, rotor diameter, blade orientation, green economy, sustainability, mechanical engineering, explainer, power supply, electricity and magnatism, tesla, efficiency, wind turbin brake, wind turbine design, doubly fed induction generator working principle, yawing mechanism, kinetic energy, rooftop wind, ted

Id: Hf875eOVrVI

Length: 22min 2sec (1322 seconds)

Published: Mon Nov 20 2023