Thank you sir Poul Ejnar Sørensen I have a question on the last slide, because as I know, the losses (HEAT) are interesting when using DC cables not AC cables ?
First of all thank you very much for this lecture and the course in general! I have a question regarding Type 3 configuration of a wind turbine generator: it is shown on the picture that it uses asynchronous generator, which means that it should be drawing reactive power from the grid. However you've stated, that because of the converter it is possible to adjust reactive power flow from the generator to the grid which contradicts the previous statement. I'm sorry if i misinterpreted some information but could you please address this? Also i'm curious about controlling the rotor speed of the generator using the converter: does that mean that the converter is connected to the pitch control mechanism drive? Thank you very much!
Dear Eugene Thank you for your good and relevant questions. Regarding the asynchronous generator, it is correct that if the asynchronous generator has a short circuit rotor then it will consume reactive power. In that case, I would say that the asynchronous generator is working as an induction generator, which courses it to consume reactive power. But if you connect the rotor through a controllable converter, then it is possible to adjust reactive power flow from the generator to the grid by controlling the converter as you mention. Many places in the literature this is called a DFIG (Doubly fed induction generator) which I (and other even more qualified experts) think is a bad naming because the generator with rotor converter is not based on induction but rather on magnetizing through the converter. But the generator is still asynchronous because the rotor is not synchronized with the grid. Regarding control of rotor speed using the converter: The rotor speed can be controlled from two sides: either by changing the (low speed) aerodynamic torque or by changing the (high speed) generator torque. You change the aerodynamic torque by changing the pitch angle, while the generator torque can be changed by means of the converter control. If those two torques (normalized because of the gearbox) are equal then the rotor speed is not changing. If the generator torque is higher than the aerodynamic torque then the rotor speed reduces because you take out more torque to the grid through the generator than you feed in through the aerodynamics. Finally, if the generator torque is less than the aerodynamic torque then the rotor speed will increase. Hope that answers your questions. Poul Ejnar Sørensen DTU Wind Energy
A very late and short answer, sorry: An asynchronous generator only draws reactive power if it has a short circuited rotor, so in that case we often call it an induction generator, which must consume reactive power. The converter sets and controls the voltage on the rotor terminal instead of short circuiting it. Controlling the rotor terminal voltage, the converter can generate reactive power for the magnetizing of the generator, and in additon to that reactive power to flow to the grid. There is much more to say to this to really understand it, but I am not able to communicate that on this chat. Regarding the connection to pitch control, it is the same work-share as for type 4: What the converter actually does is to control the generator torque, while the pitch system controls the aerodynamic torque. When aerodynamic torque is greater than generator torque then the rotor accelerates, and if it is less then the rotor speed decelerates. So you can control the speed either by changing generator torque or by pitching. At low wind speeds you are normally changing generator torque to get desired rotor speed, but at high wind speeds the generator torque is limited, so you need to use the pitch system to decrease aerodynamic torque.
Thanks for the course. Can you please let me know where am I wrong in the following thinking: It is known that Ns = Nr + 120*f_rotor/p, where the symbols have the usual meanings. The rotor frequency, f_rotor, is determined by the switching of the rotor converter. Therefore, the rotor speed is completely dependent on the switching frequency of the rotor converter. The developed generator torque depends on the slip (or rotor speed), and so is the power output of the generator. Of course, the power balance equation must come into the picture. Turbine output = rotor output +stator output. What am I missing.
Dear Sir, The connection points just above the wind turbines are shwon like RMU, are those connections provided by a RMU or with a simple tap on cable connector panels? Because some worls wide vendors are including in their wind power solutions simple cable connector panels, I am askng this question.
Hi Could you please explain how each turbine output is synchronized while combing one turbine output power to other turbine power in a group say 4 or 5 turbine finally from where single feeder is coming to the point of POC.
Great video! May I ask if (for the case of on-shore wind turbines) the power converter is usually mounted inside the nacelle or at the base of the wind turbine, close to the transformer? Thank you in advance!
Some turbines have the power converter on a separate deck, above the main entry level. Others have the power converter in the nacelle behind a arc flash rated door.
Thank you for this detailed course, DTU. A very useful resource, indeed. Prof. Sorensen, what about Power Electronics converters connected to synchronous generators? As far as I know there are HAWTs using them, am I correct? How do they work?
Thank you Roger for your question. Yes, for the type 4, synchronous generators are used by several manufacturers, but some also use asynchronous generator in type 4. The main advantage of using synchronous generators instead of the cheaper asynchronous generators is that this is more feasible if we want to omit the gearbox, meaning that the generator rotational speed must be very slow. This requires a multipole generator, which has a much higher diameter than conventional (2 or 3 pole-pair) generators. In principle, multipole generators can be either synchronous or asynchronous, but the latter will be extremely heavy and expensive, so in a practical wind turbine application, multipole synchronous generators are used.
I want to understand but still don't. I'm trying to find an explanation behind why a house-wind-turbine looses it's efficiency (slows down) when the house uses energy (increased energy demand)? Can anyone help please?
I like it but the only problem with Windturbins is that you have to build a new building every time when you are already having a lot of buildings everywhere. Just need to add the fans to generate power and connect them all back to the grid. Would that be possible in this world? Too many buildings are collapsing and too many different buildings styles and types that's not suitable to carry extra weights. Imagine every building can be a Windturbins stand.
I am interested in battery storage. How does that fit into your models? Is it best to have the batteries near the wind farm or is it best to place closer to the user? What about a country that uses tri-phase current? I am taking this course but I am in the health field. I have a renewable energy dream and so I get to ask stupid questions.
I am currently studying renewable energy engineering at uni so my knowledge is not comprehensive and I am in no position to give expert advice, but I would think from the outset it would be easier and cheaper to build and maintain a storage system nearer the point of use, especially if the power is from an offshore wind farm or an onshore wind farm high up in mountainous terrain. Battery storage, at least in the short term is being used mostly to iron out peaks in the demand due to its cost and its high reaction speed, making me think that nearer the point of use might be better. I would also try and put it at some point along the DC line before the electricity is converted back into AC for grid use, to avoid unnecessary conversions that create losses as batteries themselves are DC. Hope this is mostly correct and that it helps.
An excellent description-demonstration Teaching of how wave-packaging operates in a resonant frequency modulated network.
You can find very detailed designs and specifications as well as step-by-step instructions on Avasva.
Site loads very slowly.
Stop disturbing our 👀 with this "avasva" of a thing
Thanks for the clear list, exactly what I was looking for
@Jordan Rayan dont, its fishing
Thank you sir Poul Ejnar Sørensen
I have a question on the last slide, because as I know, the losses (HEAT) are interesting when using DC cables not AC cables ?
First of all thank you very much for this lecture and the course in general!
I have a question regarding Type 3 configuration of a wind turbine generator: it is shown on the picture that it uses asynchronous generator, which means that it should be drawing reactive power from the grid. However you've stated, that because of the converter it is possible to adjust reactive power flow from the generator to the grid which contradicts the previous statement. I'm sorry if i misinterpreted some information but could you please address this?
Also i'm curious about controlling the rotor speed of the generator using the converter: does that mean that the converter is connected to the pitch control mechanism drive?
Thank you very much!
Dear Eugene
Thank you for your good and relevant questions.
Regarding the asynchronous generator, it is correct that if the asynchronous generator has a short circuit rotor then it will consume reactive power. In that case, I would say that the asynchronous generator is working as an induction generator, which courses it to consume reactive power. But if you connect the rotor through a controllable converter, then it is possible to adjust reactive power flow from the generator to the grid by controlling the converter as you mention. Many places in the literature this is called a DFIG (Doubly fed induction generator) which I (and other even more qualified experts) think is a bad naming because the generator with rotor converter is not based on induction but rather on magnetizing through the converter. But the generator is still asynchronous because the rotor is not synchronized with the grid.
Regarding control of rotor speed using the converter: The rotor speed can be controlled from two sides: either by changing the (low speed) aerodynamic torque or by changing the (high speed) generator torque. You change the aerodynamic torque by changing the pitch angle, while the generator torque can be changed by means of the converter control. If those two torques (normalized because of the gearbox) are equal then the rotor speed is not changing. If the generator torque is higher than the aerodynamic torque then the rotor speed reduces because you take out more torque to the grid through the generator than you feed in through the aerodynamics. Finally, if the generator torque is less than the aerodynamic torque then the rotor speed will increase.
Hope that answers your questions.
Poul Ejnar Sørensen
DTU Wind Energy
A very late and short answer, sorry: An asynchronous generator only draws reactive power if it has a short circuited rotor, so in that case we often call it an induction generator, which must consume reactive power. The converter sets and controls the voltage on the rotor terminal instead of short circuiting it. Controlling the rotor terminal voltage, the converter can generate reactive power for the magnetizing of the generator, and in additon to that reactive power to flow to the grid. There is much more to say to this to really understand it, but I am not able to communicate that on this chat.
Regarding the connection to pitch control, it is the same work-share as for type 4: What the converter actually does is to control the generator torque, while the pitch system controls the aerodynamic torque. When aerodynamic torque is greater than generator torque then the rotor accelerates, and if it is less then the rotor speed decelerates. So you can control the speed either by changing generator torque or by pitching. At low wind speeds you are normally changing generator torque to get desired rotor speed, but at high wind speeds the generator torque is limited, so you need to use the pitch system to decrease aerodynamic torque.
Thanks for the course. Can you please let me know where am I wrong in the following thinking: It is known that Ns = Nr + 120*f_rotor/p, where the symbols have the usual meanings. The rotor frequency, f_rotor, is determined by the switching of the rotor converter. Therefore, the rotor speed is completely dependent on the switching frequency of the rotor converter. The developed generator torque depends on the slip (or rotor speed), and so is the power output of the generator. Of course, the power balance equation must come into the picture. Turbine output = rotor output +stator output. What am I missing.
So nice explanation. Thank you
Thanks, that was great, nice and clear!
thanks hitler
Excellent presentation thank you
Why is Thyristor ,IGBT used in Wind turbine for Grid Connection
thank you for this video
Dear Sir,
The connection points just above the wind turbines are shwon like RMU, are those connections provided by a RMU or with a simple tap on cable connector panels? Because some worls wide vendors are including in their wind power solutions simple cable connector panels, I am askng this question.
Great video....Thanks!! DD
Hi
Could you please explain how each turbine output is synchronized while combing one turbine output power to other turbine power in a group say 4 or 5 turbine finally from where single feeder is coming to the point of POC.
What would you say if I claimed a whole new design that would make wind a base load without chemicals?
What type of systems are the wind turbine electric generator and electricity storage battery systems?
Excuse me I need an explanation on how to boost the Voltage from the output of an alternator please......
Use a transformer, I used one too a three phase transformer to be precise. Cos the output was very low. Jos plateau, state 🇳🇬
Thank you for the lecture
Can we use very high number of poles for the generator in type 1? so we can avoid using the gearbox.
good morning sir
i have a small doubt what is 2 degree of freedom in emulation of wind turbine
Sir can we take state space model for wind load frequency
Greater teaching power
Great video!
May I ask if (for the case of on-shore wind turbines) the power converter is usually mounted inside the nacelle or at the base of the wind turbine, close to the transformer?
Thank you in advance!
Some turbines have the power converter on a separate deck, above the main entry level. Others have the power converter in the nacelle behind a arc flash rated door.
Thank you for this detailed course, DTU. A very useful resource, indeed.
Prof. Sorensen, what about Power Electronics converters connected to synchronous generators? As far as I know there are HAWTs using them, am I correct? How do they work?
Thank you Roger for your question. Yes, for the type 4, synchronous generators are used by several manufacturers, but some also use asynchronous generator in type 4. The main advantage of using synchronous generators instead of the cheaper asynchronous generators is that this is more feasible if we want to omit the gearbox, meaning that the generator rotational speed must be very slow. This requires a multipole generator, which has a much higher diameter than conventional (2 or 3 pole-pair) generators. In principle, multipole generators can be either synchronous or asynchronous, but the latter will be extremely heavy and expensive, so in a practical wind turbine application, multipole synchronous generators are used.
I want to understand but still don't. I'm trying to find an explanation behind why a house-wind-turbine looses it's efficiency (slows down) when the house uses energy (increased energy demand)? Can anyone help please?
I like it but the only problem with Windturbins is that you have to build a new building every time when you are already having a lot of buildings everywhere. Just need to add the fans to generate power and connect them all back to the grid. Would that be possible in this world? Too many buildings are collapsing and too many different buildings styles and types that's not suitable to carry extra weights. Imagine every building can be a Windturbins stand.
Sir I need model for ac_dc_ac data converters for small wind turbine connectivity to smart grid.for my year project ,plz help me if you can
I am interested in battery storage. How does that fit into your models? Is it best to have the batteries near the wind farm or is it best to place closer to the user? What about a country that uses tri-phase current?
I am taking this course but I am in the health field. I have a renewable energy dream and so I get to ask stupid questions.
I am currently studying renewable energy engineering at uni so my knowledge is not comprehensive and I am in no position to give expert advice, but I would think from the outset it would be easier and cheaper to build and maintain a storage system nearer the point of use, especially if the power is from an offshore wind farm or an onshore wind farm high up in mountainous terrain. Battery storage, at least in the short term is being used mostly to iron out peaks in the demand due to its cost and its high reaction speed, making me think that nearer the point of use might be better.
I would also try and put it at some point along the DC line before the electricity is converted back into AC for grid use, to avoid unnecessary conversions that create losses as batteries themselves are DC. Hope this is mostly correct and that it helps.
Why does he only show half the wires?
Thanks
nice bro
Thank you!
why is there no power poles, no wires, no evidence of a trench with all of these systems? how do they connect to the grid? theres no wires
Type 4 generator does not contribute to the frequency stability of the grid.