Ultimate Electricity Generation, HV, and Substations Course in Electrical Engineering

1. Generation, Substation, and HV Course Content: Hi, and welcome everyone to our course for electricity generation, high voltage and electrical substations. I am mad Maddie and electrical engineer. And in this course, I'm going to teach you about these three topics. So let's start by learning what are you going to get from this course? First, we are going to discuss the electricity generation. So what I mean by this, we will discuss how can we generate electricity. And we are going to discuss the different types of electrical generators, such as synchronous generators and the induction generators use in the electrical power system. We will discuss how do they work or reserve principle of operation. Then we are going to discuss hydroelectric power plants, which they use ZAP, flow of water to generate electrical power. We will discuss different types of hydroelectric power plants and how do they work. Then we are going to discuss that diesel, fossil fuel, oil and gas or plants. We will discuss how do they work. Or Z is generators, principle of operation and what are the different types? Then we are going to talk about nuclear power plants. And how do they convert the heat energy coming from zion nuclear officials to electrical energy? And we will understand the whys and nuclear energy is important compared to other types of electrical generators. Then we are going to discuss how can we generate electricity from the heat of the earth or thermal power. We will discuss what is the meaning of geothermal power plant and what are the different types of xij annual ceremony power plants. Then we are going to discuss the first or the second renewable energy source, which is that solar energy. We will discuss how can we convert sunlight into electrical power? And is that important concepts regarding xhat solar energy? We will talk about how it's as solar balance that charge controllers that involves those used in that solar energy system. Then we will talk about another renewable energy source, which is wind energy. We will talk about when the energy, how can we convert that went into electrical power. We will discuss the main concepts regarding the wind damage. You will have an excellent knowledge about wind. Then we are going to have another section. We will discuss the important definitions in generation. So in this section about the important definitions, we will talk about what the important definitions such as that characteristics of generators. We will discuss a zap cost of building each power plant. And when do we use this type of project plans and when do we use as our types of power plants? And the difference between using renewable energy sources and non-renewable energy sources. Then we are going to discuss is the high voltage generation. We will talk about how can we generate high voltage, such as DC, high voltage, and high voltage with different frequencies. We will discuss how can we build generator that will produce high voltage? Then we are going to discuss an important component in the electrical system, which is the electrical substations. We will discuss what are the different components inside our electrical substations and the y electrical substations are important in the electrical power system. We will also discuss different types of electrical substations, different types of breakers, circuit breakers, fuses, and much more in this course. Also, we will talk about with overseeing system design or does that grounding systems. We will talk about it as a important definition. Definitions regarding the Earth-Sun system. We will discuss also why. It's important. And we will discuss how can we design an aliasing system. And we will design endorsing system using a tab broken. Finally, we will talk about some basics with the electric console station design. So we'll have a small example which will help us to understand the idea behind the design of electrical substation. So if you are looking for one course that will help you get an excellent knowledge about degeneration substations and the high voltage, then this course is for you. Thank you, and see you in our course for electrical generation substations and the high water. And if you have any question, just to send me a message. Thank you and see you in our course. 2. Introduction to Electricity Generation: Hi and welcome everyone to our course for electricity generation. And this course we are going to talk about with that different generating power stations. And we will talk about with our different generators used in power plants. So first, let's have an overview of the electrical power system. So first, our electrical power system consisting of four main stages. It consisting of generation phase, the transmission phase, distribution phase, which is finally the load consumption. So first, what we are talking about in this course is generation part of electrical power. Okay? So first, here we have different generating power plants. It can be a renewable energy source or non-renewable energy source. Then after generating this electrical power, we are going to transmit it using transmission lines. Two sets Revolution network. In the distribution network, we start distributing our electrical power too different. So in this part we are concerned with generation phase. Heard is another overview of the electrical power system. You can see we have the generating station or the regeneration phase. Then you will find that we have the second phase, which is a transmission. You will find that between generation and transmission, we need to increase our voltage. Let's say e.g. we are generating at 11 kilowatt. Okay? So the power generated from the electrical power station is at a voltage of 11 kilovolt. Okay? Now in order to transmit this electrical power, we need to step up the voltage. We need to increase our voltage from 11 kilo volt to any of these values hundred 38 kilovolt, 270 kilowatt and so on. So what we are doing is that we are stepping up the voltage or we are increasing our voltage. Now why you are doing this? Because we would like to reduce the losses in our transmission lines. Okay? So when the voltage increases using an electrical transformer, the current to transform it shows our transmission line is much lower. Therefore, the power losses will be reduced. Okay? Then you can see that after the transmission system, we have that distribution network. And since we are distributing our electrical power, you'll notice that e.g. in our home, we have a voltage of 120 volt or 240 v, depending on the country. Other countries use as 180 volt line to line voltage or 220 volt phase voltage. Okay? So in order to transform from this large power, larger voltage into smaller value that's suitable for our consumer side. We need a step-down transformer. Step down transformer is used to reduce or decrease the voltage required for the consumer. You will find that we have different voltages domains depending on the customer operating voltage. Okay? Now, here is also another overview can see we have generation. Then we have the transformer. We need a transformer to step up the voltage, right? We said that we have 11 kilovolts, e.g. and we need to increase the voltage coming from the generation up to 220 kilo volt or 500 kilo volt or any value. So in order to do this, we need a step up transformer. Soul finds that we have an intermediate stage between the regeneration phase and the transmission phase. The intermediate stage between these two phases is called substation. The substation contains our transformers, contains is a protection equipment such as circuit breakers, isolators, contains all Sousa fuses, and also contains transformers, relay is, and so on. So all of the equipment which are used for protection and for stepping up or stepping down the voltage are existing in a substation. Okay? Now we will find after transmission system we have another substation which contains the step-down transformer and also contains protection elements or equipment such as circuit breakers, fuses, and so on. Okay, Then we are distributing electrical power to our system. Okay? So what is electricity generation? Electricity generation is the process of generating electrical power from primary energy sources. For electric utilities, it is a first stage, as we have seen in the power system. It is a first stage in delivering electricity to the end user. The other stages, which are transmission distribution, ends our final stage, which is lewd or the consumption of electrical power or consuming electrical power. So why electricity is important? Because, of course, it is used to run your own appliances at home efficiently. E.g. it's used in TV refrigerators, AC fan, and et cetera. It is used also in transportation systems such as electric trains, plans, electric cars, and so on. Also in the medical sector, we use electricity for X-ray machines and other medical equipment or devices that work on electricity. So what are the different sources that we use to generate electrical power? You'll find is that we have two primary sources. We have renewable energy sources and non-renewable energy source. So that renewable energy sources, which does not end these types of resources don't end. They last forever, such as e.g. Zao, wind energy, hydro-power energy, solar energy, geothermal, and biomass. This, these resources never ends or never end. For the non renewable energy resources such as oil, coal, and nuclear, natural gas. All of these have a certain time in which a will end, okay, So you don't last forever. So we are concerned with renewable energy is a wallet, is trying to depend more on the renewable energy source. Why is this? Because, as you know, that's a non-renewable energy will not exist forever. And at the same time, you will find is that these sources causes global warming or releases too much carbon dioxide, which causes the global warming effect. So we have non-renewable energy sources such as coal. When it is born, it, it produces electricity. We have our photovoltaic or solar energy, which results from the sun rays. We have wind energy which is produced with the help of Zao when the miles. We have the waterfall energy or the hydropower which is used to generate hydroelectric energy. So before we go to the types of electrical generators, we have to understand that. We are going to give a small hint of how words are non-renewable energy sources. In general, how we generate electrical power from them. And we are more concerned about that renewable energy sources such as solar and wind energy. We are going to give you in this course that pays X of generating electrical power from solar energy. And how can you generate electrical power from wind energy? We are going also to add in the future more about Z is the other types of renewable energy sources. So since we are talking about with electricity generation, we need to understand what are the different types of electrical engineering. So we'll find is that there are many, many types of electrical generators. However, if you look at electrical power system in general, you will find that we have two main types, two main types of electrical genital, which are widely used in electrical power systems. The first one is a synchronous generators. Second one is the induction generators. So these two types, we are going to discuss them in details in this course. So what is the difference between them? You'll find that synchronous generator produces or generates active and reactive power. So active power is simply, if you don't know what active power is, you have to go to my own course for electric circuits, because it is important to understand what does an active and reactive power means. For active power, active power is the power which we consume, e.g. which we consume in resistors, which we consume in. Providing electrical, mechanical power, in providing motion, and in electric bulbs and so on. So any of these powers is called active power is a power which consumes or does work. However, the reactive power Q is related to the magnetic field. So you have to understand that any electrical machines requires magnetic field, okay, in order to operate or all in order to generate electrical power. So some types of electrical machines absorb reactive power or require reactive power. Other types you can generate reactive power, e.g. is a synchronous generator, can produce reactive power, which is required to buy any electrical machines. However, the induction generator can only generate act of power. It absorbed bit skew, or requires the active power in order to operate. It cannot generate reactive power. Don't worry, we'll understand how does this work. The synchronous generator ends induction generator. In the next lessons, we will find that most of the power system generators are synchronous generators. And the Z are used in the hydro and non-renewable source, non-renewable sources of energy. Okay. So funds that most of our generators are synchronous generators. However, the inductions and it does not exist too much. It exists this rally in the electrical power system. It is used in electrical generators, produce or provide variable power, such as wind energy. You will understand that when the energy itself is a variable or a change with depending on the velocity of wind. So since it is changing with velocity of wind, it produces variable power. That's why it provides this variable power to the electrical power grid. And in this case we use induction generators. Okay? You will find that synchronous generator have zero on magnetic fields. It means that they don't absorb or take reactive power from grid. Remember, reactive power is related to the magnetic field. So they have their own magnetic fields so they don't react apart from grid exam, magnetic field can exist in the form of permanent magnets or a field winding, as we will see in the construction of the synchronous generators. In the next lessons. For induction machines, they don't have their own magnetic field. They need to be connected to the grid to be magnetized, or we need to add capacitor banks to make itself x-height. Okay, Don't worry, all of this will be discussed in details in each lesson. So what are we going to do in the next lesson? In the next lesson, we are going to study how can we generate electrical power or how is electricity generated. Okay, so we are going to discuss is our Faraday's law of induction and Lenz law. They will help us to understand how can we transform and mechanical motion into electrical power, which is, of course, most of our generators walk on the same principle. The principle of converting mechanical power into electrical power. 3. Faraday's Law of Induction and Lenz’s Law: Hey everyone. In this lesson we are going to talk about with the Faraday's law of induction and Lenz law. You have to understand that Faraday's law is really, really important because you will find it in every electrical machine. So Faraday's law of induction is used to help us understand how can we convert mechanical energy, mechanical energy, into electrical energy, into electrical energy. So find that this concept of four a day will help you understand how can we do this from mechanical to electrical or from electrical to mechanical, e.g. from mechanical to electrical, we are talking about electrical generators and the conversion of electrical to mechanical. We are talking about with electric motors. Okay? So let's understand what does this law states and what does it mean? For today's law of electromagnetic induction states that any change in a magnetic field, any change in a magnetic field will induce an electromotive force in a conductive coil that is directly proportional to the rate of a change in the inducing magnetic field. So what does this even mean? That's, let's continue for now and then we will understand everything. So it will induce an electromotive force, The call the EMF and the measured in volts, which will also create a current flow. And here is what does it mean? Okay? So first, the Faraday law says that any change in the magnetic field, so our magnetic field is measured or denoted by Phi. Phi is the magnetic flux, which you can represent the magnetic flux or Z lines of magnetic field. So the Faraday's law says that any change in a magnetic field, any change it change, any change, we represent it as a differentiation. So we'll say is that any change in the magnetic field, d phi over DT, or variation of magnetic field will induce an electromotive force. An electromotive force means E or a voltage. Okay? So any change in the magnetic field will lead to an electromotive force. The value of the electromotive force is directly proportional to the rate of change of a inducing a magnetic field. So what we learn here is that the voltage is produced is directly proportional to d phi over DT, or the rate of change of the flux. Okay? So we can remove this direct proportional to E equal to N d phi over d t, which is this low. Faraday is a positive sign. Okay? You will understand that there is a negative sign due to Lenz's law. Okay? So here E or the voltage are produced, or the electromotive force means the voltage are produced inside a coil, is equal to n, which is the number of turns of the coil. How many tones for this coin? D phi over d t is a variation of magnetic field. So it means that if there is no change in magnetic field, it means that there will be no voltage. Okay? So how can we understand this? Okay, you can see here we have a magnet. In a magnet produces magnetic field. This magnetic field is constant, okay? So this magnetic field, magnetic field is constant. Okay? So if we put a magnet like this besides a coil, okay? Is there any change in magnetic field? There is no change in magnetic field. D phi over d t is equal to zero. So no voltage is produced at the terminals of the coil. Why? Because the magnet itself is at, it's a place. It is, fix it, it produce a fix-it value of magnetic field. So the variation of magnetic field is equal to z. So there is no voltage between these two. However, however, if we take this magnet and the store to moving to the right or to the left, or move it to the right, you will find is that this coil, we will have an induced EMF. Why is this? Because the motion of the magnetic field, or motion of the magnet itself produces mixes, this coil sees the magnetic field as a variable feed. So in this case, you will find that we have a variation in magnetic field, which means that we will have a voltage. So let's see this figure to understand the idea. So if you look here, we have a magnet and then we have a coil like this, a coil like this one, which have two wires, two terminals, several coils. How many donors? 1234567. So we have n, which is the number of turns of the coil equal to seven. Now, if we keep this magnet as it is in this position, you will find that the voltage are produced at the two terminals is equal to zero. There is no variation in magnetic field. However, if you start moving this one like this, you will see that the voltage starts to be produced. Or if you move it like this in the other direction, you can see a positive, then gets back negative and so on. So you can see this motion of the magnet itself produces a voltage across the cohort, okay? If this magnitude is constant or standing in its place, it will not produce any voltage. So the Faraday's law say is that when we have a variation in magnetic field, we will have a voltage which will be produced as this voltage will produce an electric current. Okay? So let's see enormous opposition here as legs, as you can see here, that when we have a magnet like this, Okay, Let's see it. You can see when we move the magnet like this to the left and then stand still, you will find that the voltage is zero. When we start moving, you will find that the current is produced because we have an induced voltage, voltage which is produced at the terminals of the coil. Okay, so the current is formed only on the movement of the magnet itself because the magnetic field is changing with respect to this coin. The magnetic field as seen by this coil, is it changing? When we are becoming close to the coil, the magnetic field is increasing. More fluxes cutting is a coil. And the, when we start going away, the amount of flux cuttings or coil decreases. So you will see that this motion will lead to production of magnetic, production of electromotive force. When it is standard, still not moving, you will find that the voltage is zero. When we start moving, we will have and induced EMF. Okay? So the idea of Faraday's law is that when we have three elements, three elements, number one, when we have a magnetic fields, when we have a mechanical motion, mechanical motion we are moving left and right, left and right. So we have motion. When we have a wire which will take the output current. When we have this three elements, we can generate electricity. What we can do is that we can take an electric generator is, electric generator is formed of a rotor and stator. The rotor is rotating part. So when we add a magnet on the router and this rotor is rotating due to mechanical force. You will find that we will have a varying magnetic field, or a d phi over d t. And the stator is the one which will take the output voltage. We will see this in the synchronous generators and induction generators. Okay? So what about Lenz's Law? Lenz's Law is pretty, pretty simple. You will find that, that Lindsay Law states that when a changing magnetic field produces or induces a current in a conducting required. So what is the value of this current over? What is the direction of this current? Or why do we have a current? We have a current because this current will produce a magnetic field that opposes the induced magnetic field. But it's simply the induce, the current opposes the changing magnetic field, which is producing it, as shown in the figure we will see here. So as you can see, we have a magnet like this. Okay? Let's say it is in this position, North and South. So we have some flux lines here like this. Let's say it is reaching here until here. Okay? So let's say it is a standstill. So there will be no voltage here because there is no motion. Now, let's assume that we are moving from here to war this coin. What will happen is that if this magnet from this position becomes in this position, this position you will see that it cuts more of the coin. More magnetic flux will cut the coin. Okay? This motion will produce a varying d phi over DT, or a variation in magnetic flux, which will lead to production of voltage. Okay? So what do you think is phi or the amount of magnetic flux see him by the coil increasing or decreasing. Actually it is increasing because we are going close to this coin. So coming close, it means a more flux will cut this coin. So what does a solution now, I would like to produce a magnetic field that opposes this effect. So you can see magnetic field is increasing like this. We are coming close. So the magnetic field is affecting more and more zach coin. So the current will be produced the like this. Okay, So we will find that the current flowing like this, like this. Okay? So we'll find that when we use are all called Zap Fleming right-hand rule, you will find that this coil, due to the presence of a currently exists. It will produce a magnetic field in this direction, like this, north and south. So when does current flow is like this? It will produce North and South. Why is this? Because we have here north and south. North here means that it will pose, it pushes this one away, stay away from me. Okay? Now it's the same idea for this one. You see here we have north and south. Now if we have some flux cutting here like this. Now when this one moves in the other direction like this, you will find that e.g. it becomes in this position. So find that in this case you will find that it will cut like this. It will just the cost, e.g. here and here and here. The magnetic field seen by this coin is much lower, much lower. So what will happen is that a current will be produced like this. Like this by exist, I exist. Okay? According to the Fleming's right-hand rule, you will find that this one will produce a magnetic flux in this direction, like this, North and South. So what will happen is that we have this mega which is north and south. So this sounds will try to attract the snow, so it will oppose the effect. It will just try to get it back to its original position. So in the end, zach currently produced or the voltage produced in other direction produces a magnetic field in a direction that opposes the change. If this one tries to get closer and increases the magnetic field, the current will produce a magnetic field that opposes this effect. Stay away from me. If this one stays away and go away from the coil, the current will be produced here to attract it, please come back so it will produce a magnetic field in this direction to attract this magnet back again to its position. Okay? So Windsor North of the pole of the magnet in the figure above moves closer to or farther from the rope. And EMF will be produced to produce a current that will produce a magnetic field that opposes the changing magnetic field from the magnet. So here you can see this is the ID, exactly what happens. So here, when this one starts to come and get close to it, you will see that a current will be produced. The current will be produced another direction which will produce north and south. So if you have a current in this direction and this direction like this, okay? So we will have like this, okay? So the magnetic field will be like this. And we will have north and south. You can see when this one twice to come closer, a current will be produced the legs this. Why is this? Because you will see that the current Like this, like this, moving down, down, down. Which means that according to Fleming's right-hand rule, the magnetic field will be in this direction. Of course, if you don't know about Fleming's right-hand rule or all of this. You can get back to our goals of electrical machines, okay, in which we discussed in more details about magnetic flux and the magnetic circuits. So we have North and South, and this one is north and south. So as you can see, when this one tries to come closer to the coil, the current will be produced, will produce a magnetic field north and south, which opposes this magnet. When it starts going away from it, it will start reversing its direction to produce a magnetic field that will have as house and tunnels here, so it will attract this one. Please come back. So as you can see, when it comes closer, it produces a repulsion force. When it goes away, it produced an attraction force because it wants it to be in its own position, is the original position. Here is an example of the Fleming's right-hand rule. So as you can see here, here we have our code. Let's say it's a current going like this. Not like this. Let me have it in the other direction. We have positive here. So let's say the current is like this, going down like this, like this. So if you put your hand like this, you can see in the direction of the current, this hand is in the same direction of the current law exists. So we'll find that this, some of your own hand will produce the direction of magnetic field, which is in this direction. So this is the direction of current. This is the direction of magnetic fields. So the current up magnetic field on the right or the nodes, since it's the magnetic field that exists. So we have North and South. So by using this Fleming right-hand rule, you can apply it here to find the direction of the magnetic field. Here is more about eight. You can see we have a coil according to the direction of motion. This will happen. So you can see we have, this magnet is moving. So we have moving towards it. So it will produce a current that will produce a magnetic field that will oppose this motion. So e.g. in this one, it is moving like this, so it will produce north and south to oppose the effect, to tell it to go away. Here if the magnet is moving away. The same idea. This will produce North and South in order to attract it. Come back. Please come back here for this example, it's the same idea if we have North and South. But this one is the one which is moving the coil is the one which moves. This one is a stationary. So since this one is moving, it is also seeing this magnetic field as varying. Toilet try to attract it. So it will produce north and south to lead this one come to me. Okay? Same idea. If it is moving like this, it will produce also South and the North to attract this one. Okay? So in the end, it will try to keep the magnetic field is same as before. So what we learn from this, or what is the purpose of all of this, you will understand that in order to generate electricity in magnetic field, generate electricity in electrical machines, we need three elements. One, we need a mechanical force or motion. Number two, we need a magnetic field. Number three, we need a wire that will carry the output current or the wires that will have an induced voltage. So you can see here we have this magnet, which contains magnetic field, and it is moving left and right. So we have a mechanical force. Then we need the wires, the wires which will carry the output voltage or output current. Okay? So we have three elements that you will always find in every electrical machine. Okay, so let's go to the next lesson and start understanding the forest, the type which is a synchronous generators. By understanding the synchronous generators, you will be able to find disease three elements. You will find the mechanical force, magnetic field, and the wires. Okay? 4. Synchronous Generator Working Principle and its Types: Hey everyone. In this lesson we will talk about with the first type of generators, which is a synchronous generate. The same idea as before. We said we need three elements. We need forest and magnetic field. We need mechanical motion, and we need a wire that will carry the output electrical power. So how does the synchronous generator looks like? It is something like this. So the first element that we have is that we have a magnetic field. And magnetic field which will be formed using field winding. We add, we connect it to a DC supply that will provide current to a field, and this field will produce magnetic field. Okay? So this is a forest. My second semester is that we will have magnetic poles on the rotor itself, the part which is rotating. So first, we have here now and magnetic field. Second element, we need mechanical force or mechanical motion. So we have a rotating part here, which is magnetic field, and it is rotating. How it is rotating, it says connected to a shaft or connected to a prime mover, such as diesel generator or a hydropower plant, which rotates atropine and electrical turbine. And this turbine, when it rotates, it will produce this form of rotation. So rotation of this machine is due to the rotation of the prime mover, which is due to the Zao prime mover itself. So now we have a mechanical force. So this is a magnetic field and the mechanical force, the Soviet government, we need wires that will carry the output power. Will find that we have another component here, which is called the state or state or because it is in fix it, it is not moving at all. So this part is called stator, rotating part, called rule to the state or has windings. You can see one and 2.3 winding. Each of these winding represent the phase, phase a, phase b, and phase c. They are 120 degrees. You can see mechanically the angle between here and here, hundred and 20 degrees. Between here and here, hundred and 20 degrees. And then between here and here, 120 degrees. So finds that due to this rotation, each, each of these coils see different magnetic fields. Sometimes they find the phone dissolve. They get the highest value. Also times he gets the lowest value of zero times zero. So this is corresponding to a three-phase voltage output. Due to the rotation of the magnetic field. You will find that we have three phase shifted from each other by 120 degrees. This waveform is the waveform which we have in our electrical power system. Our electrical power system is operating on a three phase voltage. And the three-phase voltage is, three voltages have the same value but shifted from each other by 120 degrees. Again, if you don't know about three-phase system or the magnitude and phase shift, you need to go to our course for electric circuits. So here's the same idea. Can see we have a rotating part which is rotating due to the hydro-power plant or due to diesel generator, whatever it is, it is causing a mechanical motion. This mechanical motion. And do we have here a magnetic field on it? This rotation of the magnetic field will produce a d phi over d t, which will lead to induce the math on that state or itself on the coils of the state. You will see that due to this rotation, each one will have a different magnitude according to the position of this root. Okay? So here's the same idea. We have three equals a, b, c shifted from each other by 120 degrees. So if you don't know how you can see it likes us. Let's say here exists. We have phase a and phase C like this. And FASB is like this. If you look at this positions, it is something like this. So you can see that between here and here, 120 degrees between here and here, hundred and 20 degrees between here and here, hundred and 20 degrees. So what we can learn from this, we can learn is that the three voltages are shifted from each other mechanically by 120 degrees. And this led to what? Led to a voltage. The three phase voltages are shifted from each other by 120 degrees. Okay? So this representing our synchronous generator, we have the stator, which has a three-phase winding, which is a three-phase output of the system. You can see three-phase like this. You can see here we have the rotor which is rotating. We have two poles, e.g. it can be more than two poles. And how can we generate magnetic fields simply, we add a coil around it and we connect it to a DC supply. This DC supply, or DC voltage provides a current goal, the field, the current. This field, the current will produce magnetic fields. So when the current goes like this, goes like this or in the other direction, it will produce magnetic fields. Of course, we have discuss this in our course for electrical machines. So if you don't know about this or you don't have any knowledge about electrical machines, you can go through this course. Okay? So we have this a and b and c shifted from each other by 120 degrees. As you can see, that system, we have the field winding, which will produce a magnetic field supplied with a DC current, which gives us the excitation or the magnetic field required. So we said the first element, we need magnetic field. How did we obtain this? By connecting this rotating part to add DC supply to produce a fix-it magnetic field. Then is our root will field is rotated by an external chuffed adds a synchronous speed. The rotor itself, as this one, is rotating by an external shaft. This external shaft is connected to a prime mover, such as diesel. Working by diesel or working by hydro. Or waterfall energy. At what is the speed at which it is rotating? Speed at which it is rotating is a synchronous suite. All we say n s, you will understand what does the synchronous speed mean? That Nick has to slide the rotating magnetic field. So we have a fixed set magnetic field and it is rotating, rotating. This magnetic field, fixed and magnetic fields that rotates will produce voltages in the stator at a, B, C depending on its opposition. Okay? Why? Because this magnetic field, when it rotates, each coil, will see the magnetic field as it is it changing or as a varying magnetic field. Now, what is the frequency of the output voltage? You know that any voltage is equal to V maximum cosine omega t plus phi, which is a phase shift. So e.g. Va is maximum voltage, maximum value cosine omega t plus phi phase shift here is equal to zero starting from the zero position, omega t Omega is the angular frequency. Omega is equal to two pi multiplied by the frequency. Now, the frequency here is the frequency of the output voltage is equal to. This frequency can be 50 hz or 60 hz. This is the value of the frequencies that we produce from our electrical system. Will find that in our electrical power system, it is operating at ease, or 50 hz or 60 hz. Okay? So we have to make sure that the output three-phase voltage is 50 hz or second service. So how can we do this by controlling the rule to frequency? Or to be more specific is our role to speed. So we need to understand what is the relation between the rotor speed and the frequency of the output voltage? So here you will find an important relation. You will find that N, S, or the synchronous speed. Synchronous speed is the speed at which our rotor is rotating. Okay? So the synchronous speed is equal to hundred and 20 F divided by P. So finding that f is the frequency, alternating current frequency or the AC frequency, the frequency of this signal. So what is frequency? How many cycles in 1 s? Okay? So 50 hz, this means that our waveform will make 123 and so on, 50 of these cycles in 1 s. And the B indicates the number of poles of the rotor, you can see here and we have North and South. How many poles that we have two ports. It can change from one machine to another. So as an example, if I would like, if I would like to produce 50 hz, let's say I would like to produce 50 yd. So I need to control the rotating speed of the rotor itself. So we have 120 f a over b. So let's say I selected that the output voltage frequency is 50 hz. So I will make F equal to 50. Okay? And we see here how many poles we have North and South. So we have two poles. So we'll make B equal to when we divide this two together, we will have a speed of 3,000 rpm, or say thousand revolutions, revolutions per minute. How many revolutions in 1 min? Okay, so we need to make this rotor rotates at a larger speed of 3,000 rpm in order to have the output voltage equal to 50 hz. So you can see now that that rotor speed effect as the frequency of the output voltage. Okay? So this will lead to two types of synchronous generators. The first one which is called as salient generator, and the other types called xenon salient generate. So you can see here that two types, what are the differences between them? The difference in the router itself. So we'll find that that state or in both types is the same. Nothing has changed in the state. However, if you look at Zap Router itself, you will find that it, e.g. in the salient pole, you will find that it consisting of large pools. You can see all of moles, pool of South Pole of North pole of cells. So large pools. However, if you look at the MSA consisting of slots, this load, so we add our wiring like this. We connect the wires here so we can produce magnetic flux, unlike this one which consisting of foods. Okay? So here's another image you can see this is as salient pole and this one is unknown CDN. So we add wiring here so we can produce magnetic fields directly like this. So we have north and south, north and south. You can see it like this. Okay? We have North and South. However, this one, we can have multiple north and south. We can have many nodes and diminished house as we would like. You can see that this phi, which is a sealant, is looked like this. You can see large pool of nodes, large pool of sours, large magnets, several magnets. Or we can have a pole and we can add a wire here so we can produce flux, okay, as we would like. So that's the difference between these two types. Now, the most important thing is that when do we use the salient and when do we use among CBN. So we have the salient here you can see two, another two images for the sealant, unknown cilia. The cilia and as you can see, consisting of large number of bolts that non salient and sometimes we call it cylindrical root. Okay? You can see that this one is having large number of poles. This one has very low number of poles. So if you look at the synchronous speed, the speed at which this rule tool will rotate. Hundred and 20 F over B. Let's say e.g. I. Need an output frequency of 50 hz. Okay? Now, e.g. if you look at the sealant that we have very large number of poles. So very large number of poles, it means that we have very low speed. So you can see the salient to have a low speed or has a low speed. If you look at the cylindrical, you can see North and South poles or very low number of pores. So very low number of poles means that we will have very large speed. So you can see cylindrical rotor or the amount salient having high speed. Okay? So what we can learn from this week alone is that salient has larger number of poles, which is corresponding to very low speed. That cylindrical has low number of poles, which is corresponding to a very high speed. So this one has applications and this one has other applications. So the salient pole or the synchronous cilium to pour root or generator. We use it in that diesel generators and we use it in the hydro power plants. So when we, when we talk about z is x and we talk about the hydropower plants, we understand that the type of generate reused is as in Crohn's generate. Okay? Unlike this type which is a cylindrical water, when we talk about steam generators, we use the cylindrical rotor or the synchronous generator with a cylindrical. Okay, so I hope you now understand the difference between them. High number of poles, low-speed, low number of bolts leads to high-speed. Okay? So in this lesson, we talked about with that synchronous generator principle of operation. And we also talked about the different targets. 5. Wound Rotor and Squirrel Cage Induction Machines: Hi and welcome everyone to this lesson in our course for generation. In this part, we are going to talk about the induction machines and different types of induction machines. So what is an induction machine? Induction machine is similar to a synchronous machine. But the difference is that it has zero auto is different from the synchronous machine. Will find that as a synchronous machine has two main types. First one is called the wound rotor induction machine, and second type is called the squirrel cage induction machine. So the first type is a wound rotor induction machine. So if you look at this system, you will find that we have the wound rotor induction machine or induction generator to be more specific. Here we have this part, which is our router, the router or the rotating part. And do we have here, this part is our estate. So similar to the synchronous machine is estate or has a three-phase winding, a, B, and C, which are all connected to the power grid. Okay? Now we will find that as our router itself or the rotating part is not like the synchronous machine, consisting of three phase winding two. So it has three phase winding. Now, this three-phase winding are usually short circuit with each ours have a short circuit between each other. Or sometimes we can add a resistance to each branch, then we make a short circuit. Now what is the function of this resistor? If you have seen my own course for induction machine, you will learn is that the rotor resistance here controls the speed of the generator itself. Okay? So we can control the speed of the generator by controlling the value of the resistance. And at the same time, it has our problem is that it causes power losses. You will see some. So we have resistance here, all resistors here, we have a power losses, okay? Okay, You can see that the router itself is connected to the generator or the turbine itself. You can see as an example. As an example, the induction machine is used in the application which has variable speed. As an example, we have this when the turbine is this when the turbine rotates, depending on the velocity of wind. Now when this one rotates, we have here our router which will rotate. And at the same time we have our state. So when this one rotates and this one produces magnetic field, we will be able to generate electrical power, as we will see. So here is this type which is called wound rotor. We can see it as a wound rotor. As you can see, it is wounded router or wanted windings. This figure and this figure representing the rotor of this induction machine. You can see that we have the three phases. We have a, b, and c inside the rotor itself. Now, what we are going to do is that we do a short circuit on them. So you can see that this part is rotating all the time. And we have, inside this winding, we have a and B and C, we have three phase winding, a, B, and C, which are rotating because the whole time. And I would like to make a short circuit with Zoom, or I would like to connect them to a variable resistor to control the speed. In order to do this, we use slip rings. You can see we have rings here. You can see we have slip rings. And we have here process made of carbon in order to connect them together. Okay? So when this part is rotating, this part is constant. And at the same time you can see it's connected to a resistor and all of them are short circuit with EHRs. So you can see here we have the water itself can be represented by a three phase ABC for Xarelto. And we have the slip ring, which is the spot. Okay. Is this report is 12.3 and then we have the process 12.3. As you can see here, 12.3. Usually we make a short circuit inside our induction machine. So we can, after taking all of these branches, we will make a short circuit like this. Other times if I would like to control the speed, then I'm going to add variable resistor here, so I can add a resistor here, another resistor here, another one here. Okay, Now, the same figure for this part in real life, you can see here the rotor itself, which is connected to the gearbox, so it keeps rotating depending on the velocity of wind. And we have 12.3 the slip rings, each of these rings is connected to one phase, this one to a, b, and c. And this process will be formed with a short circuit between them, as you can see here. Okay, So here we discussed the construction itself. In the next slide, we will talk about how does this machine works. So here, here's an equivalent circuit for the system. So we have stator and we have root. We have a three-phase of the state are 12 and 3abcabc and D we have false or water, a, B, C. Okay. And this router is short-circuits with each other using the slip rings as we discussed before. Okay? Now what happens exactly in this system? So if you remember, we said we need three components. We need number one, that mechanical force or the rotational force. The mechanical force is coming from the wind turbine. Wind turbine provide the z rotation or the mechanical force to the rotor. Second part which we need, we need wires. Wires to carry the output power. So we have the stator which will provide the electrical current or the power to the power system or the grid. Now the third component which we need is the magnetic field. Okay? So the question is, where's the magnetic field? You can see that the rotor itself is a three-phase winding. So where is the magnetic field? There is no magnetic field here. Okay? So how can I excite this machine or provide magnetic fields? So here comes the idea. So first, we are connecting this machine tools, a power grid. Okay? Now this, in order for this machine to start talking, it will absorb Q2 from the grid, Q, or reactive power. Now why is this in order to provide the excitation of the machine. So it absorbs, adds the beginning q naught active power about Q or R reactive power. So it absorbed this current from the grid. So we have a three-phase balanced set current shifted by 120 degrees, IA IB IC, or IE IB IC shifted from each other by 120 degrees. So we have a three-phase balanced supply coming from the grid. These currents are equivalent to Q, or the active power absorbed bit from the grid. Then what happens is that this three-phase current supply current sensors, they are three-phase current, three-phase currents. And at the same time the audit changing with time. So this three-phase current will produce a rotating magnetic field, similar to the magnetic field. If you remember, we have a magnetic field in the synchronous generator inside the rotor, we had a magnetic field and it was rotating, rotating at the speed of the synchronous speed. That rotating magnetic field to produce the from the synchronous machine. As similar to that obtained from here. The three-phase current, which are varying Goldstein will produce a magnetic field similar to the one of the router inside the synchronous machine. So what will happen is that, that rotating the magnetic field produced from this three-phase when cut. So we have a magnetic field going through the machine, through the air gap between the stator and rotor, going to the router itself. So what will happen is that this rotating magnetic field will cut that three-phase winding of zero to sows are rotating. Magnetic field weld cuts the router causing as three-phase current. So we will vision, we will generate IA, IB, IC. Remember we have a magnetic field, the calming going to lose our router. So it will produce a voltage here, voltage here, voltage voltage here, and voltage here like this. So we have IA, IB, IC since we are short circuit, remember, wish we made a short circuit so we can produce currents. Now, this current, what will happen when we have three-phase current? This three-phase current will produce another magnetic field, another rotating magnetic field. So we have a three-phase are rotating magnetic field here. As a rotating magnetic field here, then the interaction between these two magnetic fields will lead to production of torque, okay, will lead to production of torque. So our router will start rotating. Remember this is Austin zoster. Remember this point that the rotor will start rotating. Despite having a, when the turbine that rotates. We will understand how can we differentiate between a motor and generator. Okay, So we are talking here about the principle of operation of the induction motor. Neglect as a presence of a wind turbine and assumes that we connected here in the mechanical route. But before we discuss how does induction machine operates in there? Generation mode, we will discuss first is the other type of induction machines, which is a squirrel cage. You often know that's a wound rotor and the squirrel cage operate with the same principle. So here we have the squirrel cage. If you look at the router itself, you will find that it is in the form of a squirrel cage, a cage of the square root. Like here. The phase three phase of the state or ends or water itself is in the form of squirrel cage. Okay? So we'll find that the rotor, which is used in the squirrel cage induction motor or the induction generator is known as squirrel cage rotor. The squirrel cage rotor consisting of a cylindrical laminated core. So it is format of lamination. The core itself, you can see it is cylindrical and format of laminations. Having slots for carrying, conducting parts. You will find that here the squirrel cage is formed of one. To all of these are conducting paths. Like here. All of these bars are conducting polls. And do we have here slots so we can insert this conductors. Now, this conductors are made of aluminum or made of copper. You'll find that all of these pores are zoned together at each end by a large shorting rings known as end rings. So you can see here we have a large ring here and our lungs are larger in here. You can see that both of them are short circuit with each ours. Okay? So what does this mean? How can we see is, as you can see the slides, as you can see, we have a bar, bar, bar like this, which is this conductors, and it's a short-circuit by two rings. Okay? Now, since there's a rotor part of the squirrel cage is permanently short circuit by n drinks. Hence, it is not possible to add any, any external resistance. We can not add any external resistor. So as you can see if you remember in the wound rotor, which I have discussed before, we said that we have, we had a three-phase winding like this. And we get back to understand this idea here. If you'll get back here, you will see that here for the wound rotor here, we had a, B, C, and D. We had brushes, which will make a contact between this ring and the short-circuit here. So in this pulse, I can add any resistor in external resistor. Okay? However, if you look at this one here, you will find that I cannot add any resistor. I don't have any access to that cage itself, as you can see here. So that's why it is not impossible to add an external resistance in order to have a large starting torque. You have to know that from the CEO of induction machines or from the lessons of induction machines, we said before that in order to have a lower starting torque for the electrical machine, one of the methods is that we can add an external resistor. So by changing that resistor, we can increase the starting torque of the machine. However, since we don't have any access to this cage and I cannot add any resistance. This squirrel cage does not have any, does not have a large starting torque. Your funds at the core of the rotor, why it is made of laminations and you'll find this in lots of electrical machines in order to reduce the eddy current and hysteresis losses. So how does it work? The same idea when a balanced three-phase supply is fed to the stator winding. So we add as three-phase balanced supply to it. This will produce a rotating flux or rotating magnetic field with a constant in magnitude and speed. It is beat and the magnitude, of course, dependent on the frequency of the system, pays a frequency which is 50 or 60 hz. The rotating magnetic field will pass through the air gap. And the coaches are rotor conductors. Rotor conductor parts which are stationary. This is similar to the rotating magnetic field, which is coming from the state or in the wound rotor. And the cutting is a three-phase. So you can see that they have the same ID are rotating magnetic field. The cutting is a root. So this will lead to an induced EMF or voltage in this conductors, leading again to presence of a current and the production of another magnetic field. This magnetic field of the state or the interaction between these two magnetic fields, will lead to the rotation of the rotor. Okay? So again, squirrel cage, we add three-phase supply, which will produce a rotating magnetic field. This rotating magnetic field cuts or auto, leading to currents. These currents will cause a rotating magnetic field and the interaction between these two fields will lead to rotation of the root. Same idea in the three-phase wound rotor, three-phase current lead to a rotating magnetic field. Cuttings or auto, lending to three-phase current leading to rotating magnetic field. And again, the interaction will lead to a torque. Okay? So this is a principle of operation of what? Of the induction motor. Now the question is, how can I generate electrical power? How can I generate electrical power in the squirrel cage or inside the induction as a one rotor induction machine. So the idea is pretty, pretty simple. You will find that for the induction machine, we have this curve which consisting of a torque and the speed of the generator will find that from speed of zero up to the synchronous speed. So if you remember the n asynchronous is equal to 120 f over a b. F is the frequency which we are alternating current. So if you remember, we supply three-phase current from the grid. This grid have a frequency of 50 hz. And the number of poles here, representing number of poles of the state are not zeros. Now why is this? Because the source of the magnetic field is coming from the state. Okay? So the number of poles will be for the state. Let's say we have a two poles on the state, so that synchronous speed is 3,000 rpm. Okay, remember this. So we have a 50, 50 hz supply and the synchronous speed equivalent to this is 3,000 rpm. Okay? Now, so we have here that curve from zero to the same constant speed, which is e.g. 3,000 rpm, which is what? Here we are talking about torque and speed of what? The router itself, the rotor of the induction generator or the induction machine in general. Now, if the speed of this road, the speed of this route, is what is between from zero to the synchronous speed in this range. So when n or the speed of the rotor is less than the synchronous speed. You will find that our machine is operating as a motor. You can see that the torque here is positive, which means it consumes electrical power or provide this mechanical power. It is converting the electrical power into mechanical power. Now, if you look at this curve, wins as b, it becomes great or Zan, or beyond the synchronous speed in this region, Windsor speed become higher than the synchronous speed. You will find that the torque produced by the generator is negative. What does this mean? It means that our generator is over. Our induction machine is working as a generator, providing electrical power. So in the end, what determines if the induction machine is a generator or motor? Speed of the generator itself, or the speed of the induction machine. If this bit is less than the synchronous speed, it will be motor. If the speed is greater than the synchronous speed, it will be generate. Okay. That's why if you look here at this curve, let's say Get back here. If you look here at this system for the wound rotor, it is connected to a wind turbine that rotates. So when does this one operates as a generator? Note motor operates at a generator wins as bead of water is greater than the synchronous speed. So how can we achieve this? We achieve this using the gear box. So we have a low speed of wind. When we connect this to a gearbox, it will produce a very large speed, will make this one rotates at a very largest speed beyond the synchronous speed. So in this case, you will find that our machine will start to providing electrical power to the grid. As this is the same idea in the squirrel cage. Nothing changes except that the shape of the rotor or the shape of the rotating part. Okay? Okay, So now you will find another concept here which is called the slip, slip of generate. The slope is equal to n synchronous synchronous speed and S minus a mechanical speed, mechanical speed here is the en route are also rotational speed of the water divided by the synchronous speed. Okay? Now why slip is important? Because in induction machine we use a slip or a lot. In the equations of induction machines. You will find also a relation between the frequency of the current and the slip. You will find that the frequency of the current, rotor current is equal to Fs, which is a slope multiplied by the supply frequency, let's say 50 hz. So it will be 50 yd multiplied by S, which is 3,000 minus the speed of the rotor divided by the synchronous speed sensor. We have learned that we need to increase the speed beyond the synchronous speed. Let's see how it will work as a generator. So again, if the router is accelerated to the synchronous speed by a prime mover, let's say e.g. that when the turbine the slip or dizzy and the torque will be zero. If you get back here, you will find that when the synchronous speed equal to the rotor speed, the slip will be equal to zero. If you look at this graph, is that when the speed is equal to the same chromosome speed, torque produced is equal to zero. Now why is this? Because rotating magnetic field and the rotor itself are rotating at the same speed, which is the synchronous speed. So that magnetic field widths respect to the rotor. There is no relative speed, Zr as if it is constant with respect to it. Okay? So if you have this one rotating at synchronous speed ns zero to itself. And the magnetic field rotates at what is speed at the synchronous speed. So if you have something rotating at a certain speed and another object rotating at the same speed, the relative speed between them will be equal to zero or as if it is a standard style, it is standing in its place. Okay? So in this case, d phi over d t is a variation in flux will be equal to zero and the motor torque will be produced. Okay? So the rotor current will become zero when the rotor is rotating at synchronous speed. Now when we start accelerating at a speed more than the synchronous speed, the slip will become negative in the synchronous minus n over n asynchronous will be a negative value. So we'll find that the rotor current itself will be generated in the opposite direction because it's a speed became now higher than the synchronous speed due to the rotor conductors cutting the stator magnetic field. Okay? So now we have two magnetic fields, one which is in the state are and one inside the rotor. The rotor is for me due to their status itself. Now, when the rotor itself is rotating at a speed beyond this as synchronous speed, the magnetic field itself, all start of the rotor will start the cutting against the state or magnetic field, which will lead to an induced the voltage on the stator, which will lead to generation of electrical power. Generated rotor current will produce a rotating magnetic field in the rotor, which pushes or forces in opposite way onto the state or field. This course is an induced the voltage on the stator here, on the stator itself, which will push a current flowing out of the stator winding and guinness is applied voltage. So remember that we have a voltage coming from the grid. And the wins, this one rotates at a speed higher than the synchronous speed. It will produce another voltage here, which is higher than the grid. So it will push power tools is a great. Okay, So in this case, it is working as an induction generator, or sometimes we call it as synchronous generator. Okay? So why does a synchronous machine called a synchronous machine because it is rotating at synchronous speed. Now why does induction machine called the asynchronous generator? Because it is not rotating at the synchronous speed. It is rotating at different speeds. Okay? This is beat depends on the speed of the wind itself. Okay? So what is the problem of induction machine? If you listen carefully to what I said, you will find that the first problem, it does not self-excite it. So it requires the queue from the grid to provide excitation for zero. It does not have excitation inside it. So that is the first problem, so we need to solve it. Therefore, when running as a generator, the machines will take reactive power required for excitation and installed the supplying active power back into the line. So when this one rotates at a speed higher than the synchronous speed, it will start giving electrical power or active power. So we need reactive power for producing the rotating magnetic field. Unlike the synchronous machine, which had permanent magnet or had the balls inside it, which will produce a magnetic field. However, here, we need to absorb the queue in order to produce that acquire the magnetic field. Zack, the power supplied back in that grid is proportional to the slip above the synchronous speed. So the higher the synchronous means, the more power we are going to give back to the grid. So in this lesson, we discussed the principle of operation of induction machine, types of induction machines, and how can we make our induction machine as a generator? Now what is the next lessons? We will talk about power with how can we make our machine, sulfur excited machine. And we'll talk also about what's WT fit induction machine. 6. Doubly Fed Induction Generator: Hey everyone, In this lesson, we are going to talk about what WE fed induction generator. So in the previous lesson, we discussed the wound rotor induction generator. We discussed this squirrel cage induction generator. Now we have a double effect induction generator. Now what does our lovely fit induction generator? If you remember, if you remember from the previous lesson, we said that for any induction generator we have a stator, which is this part. And then we have the rule itself. Okay? We said that the stator is a three-phase system. A three phase system, as you can see, 12.3 connected to the grid. So the stator connection is to the grid. Now, if we talk about with the router itself, we said before it is also as three-phase. Okay? Like this. And we said it is short circuit using slip rings and brushes, right? So you can see that they'll double if it induction generator is also at wound rotor. It is format of a three-phase. You can see 12.3. But instead of making a short circuit on this three-phase, we connect them into a back-to-back converter, which is connected to the grid. So as you can see that now the induction generator is supplied or connected to the grid from two sides. It's connected from the grid, from the stator side. And it's also connected to the grid from the root or site. However, the rotor is connected to the grid using a back-to-back Converters. That's why it's called double effect induction generator because it is fed from the stator and fed from the root. Okay? So it's connected from two sides. Okay? So now let's discuss how does this type of generators work and why do we use it. So in order to connect that, WE FIT induction generator to the electrical grid, there is a back-to-back converter. You can see here is a back-to-back converter or this one. This image is similar to this one. So the converter is formed of two voltages. Source converters link it through a common DC circuit. You will find that the voltage source control converter as a volt source converter is connected to the rotor terminals, is called Zap Router side converter. And the one which is connected to the transformer or the grid is called as a grid side convert. So if you look at here, we have two converters. We have between them. We can add here a DC link like this. As you can see here. That DC link is the one which link is between this converter and this converter. So what happens exactly? You can see we have here grid, which is a scene. So we have a converter which converts from AC to DC, takes at ASU of the system and converts it into DC, DC link. Then we have another converter that takes DC. And the converse is to AAC require the forest as three-phase root or the three-phase of the road. The same process can happen in the reverse direction. We can have a three-phase current coming from the induction generator router. Then we convert AC to DC, owns a DC link. Then from that DC, we can convert AC and supply electrical power to the grid. So it is bi-directional. It can provide power and Q, or absorbed per power and the q from the grid due to the presence of the back-to-back converter with a DC link. Now, as you can see here, we have our C, which is a router side converter, and the GSC, which is the grid side converter or auto side because it is close to the router. You can see this is our router. And this is a converter which is close to the router. That's why we call it the auto side converter. If you look at the other one here, it's called dread side converter because it's close to the grid. You can see we have here a filter and we have here our transformer. And this transformer is connected to its connected here to the grid. This transformer is used to step up the voltage for connection to the electrical grid. Okay? Okay, is this depends of course, on the generation voltage of this converter or the output voltage of this converter. So what is the function of these two converters? Why do we need them? Why do we add this converters? Because the converter, or SSE, which is a router side converter, this converter is responsible for. Controlling the reactive power exchange with the grid. And the variable is speed of the rotor that determines the active power flow. So it is use the tool, this one is used to control the reactive power Q, which is exchanged with the grid. And since we, if we remember before that we said we need q or reactive power in order to magnetize our row two. So instead of taking from stator and producing a rotating magnetic field, that will cut the router to produce the three phase voltages. And since I'm rotating magnetic field, we take Q directly from the grid using this two converters. Okay? So the first converter, which is a root of psi converter, is concerned with the active power exchange. That is the first function. Second function is that it is used to control the speed of the road. Now, if you join my uncle's for when the energy, you will have learned that the converter here, when we control the cannons inside the router itself, we can, we can control the speed of the root. So by controlling the speed of the rotor, we can control the act of power output from the machine itself. Okay? So you have to understand that in wind energy in general, when we have a wind turbine at a certain speed of wind, the velocity of air or velocity of wind. At each velocity of wind. As zeta is, one, optimum is speed of the rotor that will produce maximum power, okay? For each wind speed, we have one is B that is required to produce the maximum power. Okay? So we have tables and then we have graphs that will help us to determine what is the value of the speed that we need. Okay? So let's say V1 is e.g. two meter per second or five meter per second or whatever it is, there is a corresponding speed of the rotor, let's say 500 RPM as an example. Okay? So in order to achieve this optimum is speed, we have to control the output currents from this converter. Okay? So we control in general, in order to achieve these two functions of the reactive power and speed, we do a vector control over, we control the id and the IQ of the three-phase current. The three-phase current of the router. Idea, unlike you are the direct access current and the quadrature axis current, these two elements. So when we control them, we will be able to control the reactor power exchange and the variable speed or the speed of the generator itself in order to reach the maximum power. A second converter here, which has seen it is responsible for keeping that DC voltage constant and at the same time can keep the voltage output here from the converter similar to the grid, or to be more specific, synchronize with the grid. So we can say is that this converter will keep this DC link voltage at a constant value of one per unit. Or let's say any value, let's say 51500 volt. So we keep the DC link voltage of Pi controlling the pulses of this convert. So our second function is a synchronization with the current. Okay, so as you can see this two converters, one which controls speed and reactive power as other on which controls the DC link and the connection with the grid. You will find that this system back-to-back converter is available a lot in electrical power system. You'll find it e.g. in them. When the turbines, such as e.g. the squirrel cage. Also in the wave energy systems. You will also find it in the audible effect induction generator in the state, or sometimes instead of adding to the router a converter like this with us to add to the state or here, the converters here, okay? And then make a short circuit here. So there are lots, lots of co