Recently I'm also occupied with R&D on a VAWT, Aerogenatrator X, V-shaped Darrieus type turbine. Now the R&D projects on wind energy and wind turbines is emerging, a Wind Turbine Controls Work Group is launched. However the word Controls is in the work group name, it doesn't mean that it is all about the controls, since controls is about controlling a process.

Once one doesn't understand the process, most likely one doesn't know how to control it. So in this work group all disciplines involved into wind turbines are combined and very welcome. with the disciplines I mean: Aerodynamics, Mechanics, Dynamics, Modeling, Electrics, Electronics, Power Electronics, architecture, Design Engineering, Controls, non-conventional Controls, Artificial Intelligence (ANN's, FLc's etc), Mathematics, etc. so there is too much to name it. It is all into it.

I invite everyone who is interested, to participate into this work group so they can share their knowledge, upload and download papers and publications and back ground information, start, follow and participate into discussions. And there is much more to name and to do.

I hope to welcome and see you all soon on this work group and to support the research and science to gain the best for us and to support and create a better world of energy for all people around the world.

My sincere appreciation for your time.

Best Regards,

Leo de Vos PE

Could u share

Can u share some of the information regarding the work done by you till now.

The first place to start is in the 80 year history of variable-pitch airplane propellers and helicopter rotors. There have been numerous successful (and some not so successful) designs employing mechanical, hydraulic, and electrical mechanisms. Curtis-Wright made electrical pitch controls in the 1940s while Hamilton Standard dominated (and still dominates) the hydraulic designs.

I am not suggesting that airplane propeller technology will translate directly to wind turbines, but it is a good starting place and will save having to re-invent well tested concepts. It will also help eliminate some bad ideas by knowing why they did not work.

Personally I do not like wind energy because there is so much talk of it wasting no resources but look at how much magnetoid rock they use! They could use that in many difference sources of energy too!

Its not about liking or disliking of any renewable energy form.Its about using it and with the maximum efficiency that we can.R&D is a must for that sake.

Well R&D is needed to make any advance in a certain topic. I believe that Geothermal and Solar energy is best because both create electricity directly such as solar uses it's radiotions and geothermal has heat which create the weak force energy.

I do agree with you Mr.Sharma.Best is dependent on the location I suppose.

Indeed because of course solar panels would not be good in a place with little sunshine like Greenland and of course geothermal energy would be hard to acquire in a highland!

I would love to share the R&D. I tried to reply many times and give any comment, but somehow in he first place I couldn't read any comments I received, and in the second place any reply I tried to give didn't go to the server of Researchgate for some reasons. It appears that I'm back on-line by now. I hope you all were not in any sense of desillusion and disappointed.

I do agree with Jonathan Allen. There is a similarity between the variable pitch of propellers of airplanes and rotor blades of helicopters and those for wind turbines. However there are a few very important differences, which make it necessary for a different approach.

1. blades for airplanes and helicopters are designed for propulsion so the air is taken in and pushed away in such a way that the incoming air is coming from a area as wide as possible to realize a desired level of accelaration of air into the direction of the thrust. The blades of a wind turbine are designed for another purpose. There it is the main target that the inbound air moves along the blades in such a way that most of the inbound stream has to pass the blades and will take part into moving the blades. The angle of attack will have a different result caused by different aerodynamics properties. But still there is any similarity with the blades of e.g. helicopters.

2. The rotor blades of large wind turbines are much larger than those from helicopters and airplanes. This implicates that the wind properties can or will vary a lot along the blades. Considering this R&D with horizontal axis turbines, this means that the blades in the lower area experience most likely less wind velocity than the blades in the upper area. R&D considering the wind properties at different heights shows a lot of difference between wind below 40m, from 40m up to 220m, and 220m and higher. The turbulence differs as well at different heights. This causes a lot of difference in blade-torques, blade flapping, blade-stress etc. So a more sophisticated approach will be required to solve this more complicated process of wind with all its stochastic properties.

Thank u very much sir for explaining this difference

Some basic considerations in advance:

Rotational wind field by design of the blades:

This R&D does not consider the blade designs, therefore there is assumed that the blade shapes have the properties as comparable with the properties acquired by circulation control. This means, to acquire the highest aerodynamic efficiency the shape of the blades and design of the rotor is such that every particle of inflowing air is actually passing the blades and by then taking part in the propulsion of the blade (the energy conversion from wind into rotational movement). Assuming this will happen at the standard rotations per minute (about 27 rotations/minute), the controls will have to control the pitch angle of each rotor blade separately without causing any deviation and variance of the rotor speed.

The main target of this R&D is reducing any mechanical wear without compromising the efficiency. Secondly the target of this R&D is increasing the efficiency by eliminating or reducing energy loss caused by mechanical distortions and dynamical influences.

The controller has to be a template for other turbines, which means that larger systems can be entered just by entering the new wind turbine parameters into the controller.

The amount of sensors has to be minimized to prevent any extra maintenance and system failure by sensor failure. An increase of robustness and reliability is desired. Data clustering might be required to achieve this.

Mr. de Vos, Your latest comment is most useful. While I was aware that wind speed varies (generally increasing) with altitude, I had not made the connection to realize that a large wind turbine subtends a significant velocity difference. One therefore has to employ cyclic pitch control. (I borrow the term "cyclic pitch" from helicopters where the forward airspeed is added vectorially to the tangential velocity of each blade. Unless one reduces the pitch of the advancing blade and increases it for the retreating one, the greater lift on the advancing side would cause the aircraft to roll toward the retreating side. If I remember correctly, it was Igor Sikorsky who solved this problem.) In a big wind turbine a blade must, in general, increase pitch at the top of its rotation and decrease it at the bottom.

I gather from your description that the wind farm would have a sensing tower with anemometers at various heights in order to derive the wind speed profile and use it to control both the cyclic pitch and collective pitch of all the turbines. Do we assume the profile is pretty constant over the area of the wind farm so we would not need sensors for each unit?

You are quite right. This control problem is considerably more complicated that that of an airplane propeller where one adjusts only collective pitch. Even the helicopter, although it has cyclic pitch control does not have to deal with the varying profiles that you anticipate in a wind farm.

Question: Do existing wind turbines routinely use cyclic pitch? If so, how much does it increase the effective power output compared with only collective pitch control?

Dear Jonathan, answering your questions, yes they have cyclic pitch control in a certain way, by each blade seperately. Not derrivated from the rotation angle, but related to the experienced wind. I cannot tell you how much the efficiency increases by this type of control.

In the R&D I accomplish, I borrowed ofcourse some relevant aspectss from the helicopter controls, like you mentioned. There, according a helicopter I'm familiar with, the pitch of the blades is corrected at a rate of 400 times per second, when the rotor is at full speed. So I determined to have the pitch of each blade corrected every 6 degrees of rotation, so 60 times per revolution. Considering the amount of inputs and the count of itterations to accomplish the calculation of the right decission, there is a lot of computing for each correction to do. So a very efficient algorithm will be required.

In case of a wind turbine blade there are a lot more parameters in the algorithm just because of the length of the blades and the variance in wind specs they experience along the blades. More considering this is to come.

At some points I do agree with Aryankumar Sharma. Considering the magnetiod rock I can say that an enormuos amount of other applications are already using and requiring that resource and therefore the application of magnotoid rock by wind turbines is not as significant as we might think. Next to this, recent R&D has discovered other methods to produce permanent magnets from composite materials which have even better permanent magnetic properties than the current magnets. About the application of wind turbines, a report of some years ago, stated that the production and assembly of a wind turbine (inclusief production of its materials and transportation etc) probably costs more energy than the turbine will produce in its entire life. I didn't figure out if this is true and never have read any comments on this. Nevertheless referring to other kind of renewables like solar, geothermal and hydrothermal, it is common knowledge that they are not always under any condition available. So best way is to consider the paramters of the location and environment to determine what is required and what is best possible. Even combination of those will provide best solutions. For solar energy you need battery storage in case of power needs after sunset. Geothermal is not possible at any location. And wind is very stochastic and hard to predict. You can count on its yearly average, but not what it will be tomorrow or the next week. So one has to consider all the advantages v.s. disadvantages and finacial resources on a location to determine the best solution. I'm not a big promoter of wind turbines and do more into solar for my region, but I admit the convienience of the conversion of wind energy, since there is wind at night times and by that means can reduce the amount of battery storage for solar-PV aplications, signifficantly. Geothermal can convert 24/7, but cannot be applied on any location, neither solar. Solar isn't very suitable at arctic regions, and geothermal is hard to apply into some metropolitan areas or in the region of oil fields. So every situation is different and has it's own characteristics and demands. In most cases combinations make the best fit.

The greatest advantage of most renewable energy systems beside being environmental benign is that they are also site specifics in a decentralized manner to reach greater number of people that would ordinarily be left out of the energy cycle because of their locations or otherwise. On blade pitch controller, since we all know lift or drag of turbine blades depends majorly on the pressure difference between the upper and lower surfaces of the blade, a system that can maximize this variables may not be a bad idea. I support more study on cyclic pitch control and a reduction in the number of electronic sensors that are prone to failure in the least expected time.

Dear Dr. AJAO K.R. I fully agree with the amount of sensors, which should be reduced because of reasons to eliminate the chance of malicious inputs, which will result in unreliable control outputs. Therefore I apply clustering and pattern recognition. In the initial model I use 72 sensors, 24 on each blade. With the results I'll try to profile the pattern of measurements and will accomplish R&D to consider if any kind of pattern recognition or paatern clustering will be suitable to reduce the amount of sensors. I even try to correlate a relationship between the pattern of these sensors and the axis torque readings. I know for now that there will be a relation between those, but now it is more to develop an algorithm for the computing system, which can bond the relationship in a reliable way.

That would make the system a lot cheaper and the controls even more reliable. Going on in this process of R&D on the new approach of a pitch controller for large turbines with large blades, a long way of unexplored issues occur, which take part of the final solution. I knew before I started that this was a long way to go. But nevertheless, the results will be valuable, even for any next development.

We are lucky that now today, we have the computing capacity to explore and evaluate those algorithms, which we couldn't use in a small environmental space like the nacelle just 20 years ago. I'm running simulations right now within a few minutes, where they took several days of computing time 2 decades ago.

I'm lucky to be not the only one to recognize these problems, and so many others have brought and publicated parts of the solution, or at least created a vision which points to possible solutions. On first sight the complicity of this cyclic control might not appear to be a large scale complicity, but reading all the papers and considering the amount of papers comparing next to the inventory and initial simulation and pre-R&D, one cannot deny anymore that this subject is really a challence to defeat.

So I continue in the spirit of engineering to make the world a better world (IEEE) and to succeed in paving the pathway to a solution to higher efficiency and improved reliability without compromising any quality.

Aspects to consider about efficiency and mechanical wear.

Some basic considerations in advance:

Rotational wind field by design of the blades: This R&D does not consider the blade designs, therefore there is assumed that the blade shapes have

the properties as comparable with the properties acquired by circulation control. This means, to acquire the highest aerodynamic efficiency the shape

of the blades and design of the rotor is such that every particle of inflowing air is actually passing the blades and by then taking part in the

propulsion of the blade (the energy conversion from wind into rotational movement). Assuming this will happen at the standard rotations per minute

(about 27 rotations/minute), the controls will have to control the pitch angle of each rotor blade separately without causing any deviation and variance of the rotor speed.

The main target of this R&D is reducing any mechanical wear without compromising the efficiency. Secondly the target of this R&D is increasing the efficiency by eliminating or reducing energy loss caused by mechanical distortions and dynamical influences.

The controller has to be a template for other turbines, which means that larger systems can be entered just by entering the new wind turbine parameters into the controller.

The amount of sensors has to be minimized to prevent any extra maintenance and system failure by sensor failure. An increase of robustness and reliability is desired. Data clustering might be required to achieve this.

Mechanical wear and loss of efficiency:

- Teeter;

- Blade flapping;

- Blade oscillations;

- Blade inner torsion and stress;

- Dynamic torques in rotational plane;

- Dynamic torques in the azimuth plane;

- Pitch bearings;

- Train bearings;

- Dynamic shaft torques;

Loss of efficiency:

- Shaft torque fluctuations;

- Accelerations - decelerations;

- Rotor speed, wing tip velocity;

- Turbulence behind the blades;

- Angle of attack;

- Circulation of the wind field;

Mr de vos

Your last comment was actually the most useful!

Recently I'm also occupied with R&D on a VAWT, Aerogenatrator X, V-shaped Darrieus type turbine. Now the R&D projects on wind energy and wind turbines is emerging, a Wind Turbine Controls Work Group is launched. However the word Controls is in the work group name, it doesn't mean that it is all about the controls, since controls is about controlling a process.

Once one doesn't understand the process, most likely one doesn't know how to control it. So in this work group all disciplines involved into wind turbines are combined and very welcome. with the disciplines I mean: Aerodynamics, Mechanics, Dynamics, Modeling, Electrics, Electronics, Power Electronics, architecture, Design Engineering, Controls, non-conventional Controls, Artificial Intelligence (ANN's, FLc's etc), Mathematics, etc. so there is too much to name it. It is all into it.

I invite everyone who is interested, to participate into this work group so they can share their knowledge, upload and download papers and publications and back ground information, start, follow and participate into discussions. And there is much more to name and to do.

I hope to welcome and see you all soon on this work group and to support the research and science to gain the best for us and to support and create a better world of energy for all people around the world.

My sincere appreciation for your time.

Best Regards,

Leo de Vos PE

To all participants and those who want to participate,

I would be grateful to invite you to the work group of Wind turbine Controls. For those who are not invite yet, I would kindly ask to accept or send an contact request, so i will be able to add you to the work group. If there are any questions, please feel free and don't hesitate to contact me at any time.

I wish you all the best and prosperity in your scientific careers.

Best regards,

leo de Vos PE

Dear Mr. Alexander Viehweider,

this is my particular interest as well. an iteresting point of view is that Europe and the U.S. have both a quit opposite interest into this. E.g. Europe wants to have their renewable sources connected to the grid to reduce the CO2 emissions, meanwhile the U.S. want to use grid connections to improve the grid stability and improve the quality of the distribution. Most interesting and quite opposite is the vision of most electricity suppliers and distributers in Europe, because they suppose that grid connections by wind farms might do any harm to the quality of their electricity distribution. There are many papers published about this. The IEEE has forums wich pay special attention to these opposite visions.

My personal vision is that it only will improve the grid. I have an almost infinite desire to prove this. If I had a few million dollars in my pocket, I surely would demonstrate this to the scientific world.

Recently the work group on Wind Turbine Controls experienced some file uploading issues. I am very glad to pronounce that these issues are solved.

We were working on the upload issues. I examined and studied the code and the routines with their class, modules. And only found that there was a certain hangup once the save button was clicked. The code returned again to the file selection routine instead of stepping to the submit routine. I couldn't find out why since I'm not the IT programmer. Nevertheless I suspected that the issue was on my side so I fixed and re-installed the latest versions of Flash Player and Java. But the result remained the same.

In the meanwhile I informed the ResearchGate team about my progress, and that I couldn't go any further than this.

I couldn't sleep very well without this being solved, because I want to run with the work group, so I started once over with some more advanced programming tools and figured uot that on the windows 7 platform I run on this moment, with IE9, the code forced for some reasons the "document mode" to the IE7 standard. I made that inadvertent switching impossible by configuring the IE9 to disable the possibility to switch to the "IE& Standards" Document mode. And guess what, the problem was solved.

This issue only occurs in Work Groups "file uploading" and nowhere else.

The reason I write this to all of you, that is if you experience the same problems, you know by know what the solution is, so you don't have to have any frustration about this, and upload your documents as you want.

i have already made a folder structure that you can use. 41 documents with background information are already in the "Background Information" folder.

I hope I have you all informed in an appropriate way. I wish you all the best and effrots into this work group.

Best regards,

Leo de Vos

It is an interesting subject and several years ago I got involved in a pre-project which was not lead to a positive end due to lack of understanding exactly of the aspects you mention. I insisted that the subject is in fact much more complex but the financial support was not open enough. I would be interested to get more input and may be within some time availability limits do some thing.

I'm trying to get some funds. But funraising in this time with the Euro and Dollar crisis is not really easy. And 2012 isn't even more promising.

The work group on wind turbine controls is emerging in a good pace. I still miss some of my followers. The work group is now reaching a more interesting level. Documents are uploaded and there are already many discussions and refers to interesting links for simulations. see my latest comment below: I hope to see the rest of my followers soon into the work group to welcome everyone.

I wish a good day for all members,

Like all discussions are for all members, I want to send this information extra to all members so everyone can go on with building, modelling and simulate their R&D. I sincerely hope that this is very helpful.

If there are any questions, comments or remarks, please don't hesitate and feel free to ask me at any time.

There are already about 86 back ground files and papers uploaded and Mr. Amer kareem, recently uploaded a 134 pages Msci thesis, which is very contributing.

I pray for us all that this may lead to excellence in the R&D of this work group.

Below are the links I refer to.

http://wind.nrel.gov/

https://wind.nrel.gov/forum/wind/viewtopic.php?f=2&t=363

http://www.ict-aeolus.eu/SimWindFarm/tmodify.html

http://www.ict-aeolus.eu/SimWindFarm/index.html

http://www.ict-aeolus.eu/SimWindFarm/download.html

Contact Information

The SimWindFarm toolbox is currently maintained by Maryam Soleimanzadeh Automation and Control at Aalborg University. Any questions or bug reports please contact Maryam.

The last major revision of the SimWindFarm toolbox, where the assumption of Taylor’s frozen turbulence was removed, has been developed by Martin Nygaard Kragelund. The wind generation in this version (No Taylor) has been based on an implementation provided by Vedrana Spudic at the University of Zagreb.

Thanks goes to Jacob D. Grunnet who developed the toolbox, Mohsen Soltani who created the case study the toolbox is based on, Torben Knudsen for providing the wind field generator, Gerrit M van der Molen for his many contributions, comments and suggestions as well as the entire Aeolus project team.

I hope this is enough information at the moment.

Note: It requires MatLab 10 and Simulink 7. At a lower version you can do the original blocksets, but once you are going to build your own code, there will occur all ind of incompatibillity issues.

I have made the wind model 3D, have placed all kind of sensors on the blades, created an individual pitch control (on which I will do R&D on different kind of controls) several control loops and now I'm building the teeter with its sensors and hydraulic compensators.

Best regards,

Leo de Vos PE

The statement of Alan Tricklebank, "With wind turbine sizes now scaling up to 5MW and beyond, the top-head mass is virtually double that of the current mainstream sizes,” says Alan Tricklebank, author of the latest Wind Energy Update" declares clearly that the top head mass doubles with 5 MW turbines and upward. So will will be the efects of excessive vibrations caused by less optimized pitch controlls. By the adapted ne approach the foundation can be reliefed of a significant extra load, resulting in a cost saving product.

See the link: http://www.windenergyupdate.com/offshorereport/?utm_source=WEU-portal&utm_medium=pressrelease&utm_campaign=1945

It's a pitty that the full report is very expensive (1395 UK pounds, more than 2500 USD) for just over 100 pages. I will look what the IEEE has to offer, within a similar context.

Leo de Vos PE

I like it

https://web.stanford.edu/~boyd/papers/pdf/wind_turbine_pitch_opt.pdf

http://ethesis.nitrkl.ac.in/2430/1/Pitch_Control_of_Horizontal_Axis_Wind_Turbine.pdf

http://mragheb.com/NPRE%20475%20Wind%20Power%20Systems/Control%20of%20Wind%20Turbines.pdf

http://shodhganga.inflibnet.ac.in/bitstream/10603/30/9/chapter%204.pdf