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Abandon the direct drive wind turbine

Abandon the direct drive wind turbine

Abandon the direct drive wind turbine

Use hydraulics. I am not suggesting a 100% hydraulic drive such as attempted by Parker Hannifin, or Mitsubishi with their Sea Angel. These, and all other such attempts, failed. Not technically, but economically.

In my proposal, analysis attached, a variator would handle as little as 11% of the total power. A hydraulic variator would be the most effective. Most of the power is handled by a gearbox.

This technology is not only simple, it would be the most important improvement possible in wind turbines because it would eliminate the power electronics. Power electronics are inefficient, delicate and expensive, and they produce dirty power. Wind power cannot reach its full potential so long as it requires power electronics, as every current commercial turbine does whether geared or direct drive.

Excepting DeWind, which demonstrated a way to eliminate the power electronics with their 8.2 and 9.2 turbines. I am proposing a different way.

It is not possible to eliminate the power electronics with direct drive. Furthermore, direct drive is the heaviest and most expensive technology. It has other serious problems that cannot be solved, such as the requirement for huge quantities of expensive rare earth magnets which will become ever more expensive and difficult to obtain. Direct drive should be relegated to the museums.

But the folly of direct drive is maintained by a powerful cult whose members insist that it is more reliable than geared turbines because it has fewer parts. This is a specious argument. It ignores at least two other important factors that determine reliability: the reliability of each part and the method of mounting and operating the parts.

One reason that gearboxes have unjustly acquired a bad reputation in wind turbines is because of the way in which they are mounted in a typical wind turbine. In these arrangements, the gearbox serves as a bearing for the rotor shaft. This imposes harmful external forces on the gearbox that it should not be required to handle. Some manufacturers such as Alstom, now owned by GE, recognized this problem and invented a solution:


Another reason is that, so far, all wind turbine gearboxes have been of the planetary type, which suffers from numerous inherent faults. That subject requires a doctoral thesis, so I won’t try to explain it here. I have written a paper on it. I will provide it upon request. It is a short paper.

A third reason is the effect of reverse or transient torque on wind turbine gearboxes. If it is not eliminated, gearboxes cannot achieve their potential life. See the excellent articles on the Windpower Engineering & Development website about torque reversal, for instance:




and others of which there are many, such as:



Gearboxes can be extremely reliable. A ship’s gearbox can outlast three ships if treated properly. A wind turbine gearbox can be made as reliable as that by adopting a few simple changes in the way in which it is mounted and operated, and by replacing the planetary type with the far more effective multi-branch parallel shaft type.

The only way to greatly improve wind turbines is to give up the fanatic, false belief in direct drive and come to our senses about the value of geared turbines.

The best way to bring wind power to its fullest and most effective use is to combine hydraulic power with a gearbox, as explained in the attachment.

RE: Abandon the direct drive wind turbine

Is there a question here?

RE: Abandon the direct drive wind turbine

Good question. Since I did not ask any questions, why did I post this stuff?

One reason is legal. I wanted it in the public record so that others could not claim it. There is a chance of that.

Another reason is that I think it is valuable information. It is the result of many years of work. So far, I have had no success in my effort to interest others in it. Maybe it would help to publish it here. Anyone who uses it would be under no obligation of any kind whatsoever to me or anyone else.

The technology requires hydraulics. Anyone who studies the information will find that it presents an important opportunity for the hydraulics industry.

It would also allow for a vast improvement in wind power. This is essential in the fight against global heating.

There is an implied question in my posts. Why does direct drive exist? It is clearly foolish for wind turbines of about 1 MW or higher. Wind turbines of 15 MW will soon be common. They will be direct drive. It is long past time to abandon this technology.

RE: Abandon the direct drive wind turbine

The only thing I see that is different is the CVT and that isn't hydraulic.
Have you built a prototype yet?
My company sells motion hydraulic motion controllers. We have been involved two projects controlling wind turbines. Non have been successful so far for various reasons. In both cases I saw that the people were not good enough engineers to really understand the problem and have the financial backing to get prototype to work where the motion controller could be applied.

I didn't see anything about feather the propellers when the wind gets too high. There is a video of a Vestas wind turbine flying apart in high winds because it is spinning too fast.
Vestas is laying off people. I wonder if wind power has a future or is it just a cool idea.

I don't see the need for a CVT or gear boxes.

The tricky part is the turbine blade pitch control. The turbine blades can turn a hydraulic pump but the hose can't get twisted to much. Down below a couple of motors on one shaft can turn an electric generator. The speed of the generator is crude but can be easily kept in a safe range. The hydraulic motors are on the same shaft connected by simple clutches. The motors are turned by oil but the flow is controlled by only a simple on-off valve to reduce pressure drops. This part is easy. No servo control here. The magic is converting the generator power to line power. It can be done but I wonder about the efficiency of everything.

Peter Nachtwey
Delta Computer Systems

RE: Abandon the direct drive wind turbine

PNachtwey, I thank you for your post. It is interesting. Partly wrong and partly promising, with an attitude.

For what is wrong, see your first sentence. The ENTIRE difference in my proposal is that I am using a CVT in the wind turbine. Only DeWind has done this before with any success, and the CVT I am proposing is different from DeWind's. Your claim that the CVT is the "only" difference is, to say the least, astonishing.

So is your objection that I didn't mention blade feathering. I didn't mention the color of the paint on the gearbox either, which is about on the same level of concern so far as my analysis goes. Yes, blade feathering is an important means of control. It would be part of the design. But we can take care of that later. First thing is to determine the basic arrangement.

You seem to confuse the variator with the entire CVT, which is the combination of the gearbox, the variator and the control system. How do you know that it "isn't hydraulic"? If you have read the CVT paper I posted, you would know that I recommend a hydraulic variator and give my reasons.

Anyone who has studied CVTs will understand that the principle of my arrangement is not new. But my analysis is, so far as I know. It works out important details I have never seen elsewhere. One reason for my post is the possibility of learning that my proposal is not new and may have already been tested.

Also new is the information about a new kind of gearbox, which I presented in the other paper. I propose to use this new gearbox as part of the CVT I described.

One of the interesting parts of your post is that your company provides wind turbine controls. That knowledge would be essential if my proposal is to be put to the test. I have no expertise in control systems.

Your last paragraph is also interesting and good. It provides useful technical information.

If you have the time, I hope you will explain why you believe that we should forget about CVTs, gearboxes and wind power.

I attach a photograph of a working model that demonstrates not only the principles of the papers I posted earlier, but some others.

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