Controller for Windmill Generator

Please rephrase the question so as to convey a clearer meaning.

I would definitely phase it into the wind, but you will have to get out of your auto to do it whenever the wind changes direction.

Hope this helps.

I think that the Gentleman concerned needs equipment (the best...he said) for taking the 3 phase electrical output of a windmill and making sure that it is correctly phased to the local grid before being attached to it for power generation.

(Done incorrectly it could happen that the whole generator head could get severely damaged or even physically ripped off its pedestal if for example it was connected 180° out of phase.)

Conversely, when the wind drops and the generator output or the frequency starts to drop, the windmill must be taken off the grid, or you could end up with current from the grid driving the windmill into becoming the world's largest hair (field?) dryer!!!!

Therefore good reliable equipment is needed for such a job. Please contact him if you know of such equipment.

Andy,

Just when I was laughing over Guest's post of "phasing into the wind" ......

You may well be right in what he is looking for.

However I would expect that equipment to be attached to his inverter, or be part of it, since I don't see how he could sync a wind driven alternator to a fixed frequency grid. Normally the windmill output would be rectified and fed to the batteries and the inverter which would supply the AC at a fixed frequency.

To achieve a fixed frequency from a windmill is certainly possible, but would require some complicated controls, variable pitch blades and would end up being a lot less efficient at capturing wind energy overall, unless one used a kind of reverse VFD, where the input frequency can vary but the output is fixed. I would assume these are available but I don't know for an installation such as his. This type of frequency converter would prevent power from being fed into the windmill from the grid.

Greg

Xantrex has a facility in Berkley that designed and built high power solid state inverters and controllers for the wind farm located near Palm Springs. These units could control megawatts of power. And as Andy said, the windmills on line do sync with each other although the prop orientation never quite matched each other. <grin> being a car enthusiast who is used to cams, cranskshaft, and pistons being mechanically locked in step I felt this was sloppy looking. <grin> but what the hey! it works don't it?

Elnav

Its actually quite simple when you know how.

The windmill is brought up to a speed (through control of the blade angles) so that for example in a 50HZ country, the generator is revolving at a speed of 50 HZ + a tiny bit more. The phase angle is measured simply with three voltage detectors for the following:-

(Here assume that the phases are labelled red, yellow and blue for simplicity). One voltmeter is connected between Red of the windmill and Red of the grid, the next is connected to yellow of the windmill and Blue of the grid, the last is connected between blue of the windmill and yellow of the grid. (We used to do this with bulbs via transformers in the Royal Navy many, many years ago!!)

Think of lamps for a second instead of voltmeters:-The lamps will only light when there is a phase difference over the lamp, eg a voltage difference. When a lamp is connected over the same phase on both generator and grid (the red lamp for example) and the phase difference is 0° there will be no voltage difference, therefore it will be off.

At the same point in time, there will be a maximum voltage difference between yellow Gen and blue Grid and blue Gen and yellow Grid, eg these lamps will be fully on....

Due to the minor plus speed difference, the red to red phase will be not lit when all three phases match (in phase with each other), but the other two lamps will light at a max together, the lamps that are on will be "revolving" slowly due to the speed difference that exists at that time between grid and generator.

We used to use a clockwise direction for oncoming generator having a slightly faster rotation than the grid and anti-clockwise for when it was too slow.

Wait till the situation is exactly as I said - lamps on revolving clockwise, top lamp off, both bottom on and then connect the generator and grid via a breaker. If you are really clever, you switch just before "Top dead center", a few degrees only though.

Once connected, the phases lock into each other and remain together. To transfer power to the grid, the blades of the windmill will now adjust themselves to make maximum torque with the avialable wind.

No generator is around that could supply enough power to physically raise the frequency of the grid, the only effect is that the current flow from the generator is now raised to the max possible - eg. you are now supplying the grid, in phase with the grid.

I am sure that modern electronics have taken the place of the lamps and phase meter that we had!!!

Note.Have you ever seen a wind farm where several windmills (of exactly the same design type of course) can be seen revolving exactly in phase with each other? Never one going faster or slower than the rest (except when starting up or shutting down of course!)....Well now you know the reason why!

Also, this makes design easier as there is only one speed/frequency to really worry about!!!

I hope that this makes the problem clear in a relatively simply fashion, but if not, ask again and I will do my best for you. With regard to the modern electronics, I am afraid I have no contact anymore with such things, but there must be many companies who make and supply such equipment.

In simple terms the question now refers to synchronising the windmill with the grid.

There must be electronic whizz-bangs that do this task, available over-the-counter to add to a home-brew windmill. Package windmills will have the whizz-bang already fitted.

Exactly!

Victron Energy makes a power manager for marine use that syncs a generator with incoming shore power so you can use both at the same time. I don't know if it has the versatility to mange a wind generator...

No it doesn't! I use Victron products in my system designs and make use of the power line sync feature. There is no control in these inverters that would directly control a wind generator.

However there is another method. On the wind generator controls I used to design and build way back when; the interface between wind gen and grid was a Gemini sync inverter. It took variable frequency AC from the wind gen and chopped it up, then used a regulated stage to convert to grid voltage and a clock circuit synced to the grid, regulated the output frequency of the inverter output. Power transfer from wind gen to grid was accomplished by adjusting the output voltager to cause a current flow towards the grid. In the event of a grid power outage the frequency was lost and this triggered a disconnect. Something the power utility was quite emphyatic about.

This same kind of power regulation is used in simplified form inside many universal voltage / frequency battey chargers. The charger doesn't care about incoming power since it chops it up and then regulates it as is done in any switch mode power supply.

Xantrex merged three companies into one in an effort at dominating the alternative power market. In the process they dismissed much of the surplus staff.

These unemployed engineers formed new company called Outback. This company is in the forefront of grid-tie and off-grid power generation and control.

Their inverters already have the capability to manage wind generators, solar panels and water turbines and then synchronizing to the grid for selling back surplus power to the utility.

elnav

Andy,

I understand matching the phases, however the OP didn't mention the size of his wind generator, and I am assuming it is of the smaller variety, (1-15 kW) in which case the blade angle servo controls, brakes, etc, to maintain a given rotor speed in varying winds is not the most efficient way to go at all, in terms of cost, complexity, and the average amount of power you could extract from the wind at lower velocities. Most smaller wind generators have limited blade angle control, or just the ability to "feather" them in the event of very high winds, to avoid damage. The concept is to extract the maximum amount of energy from whatever wind is available at the moment, rather than controlling the rotor speed, and the inverter approach is far superior for this in smaller units. Larger units typically have 1 or 2 speeds that they operate at in order to synchronize with the grid using electronic controls as you stated. The OP may well be asking about a larger unit of 15 kW and up, in which case you are right.

In the meantime, we are left guessing as to what size he means.

A few links to wind generators:

http://www.bergey.com/

http://store.altenergystore.com/Wind-Systems/Wind-Turbines-Electric/Grid-Tie-Wind-Turbine-Kits/Bergey-Windpower-Excel-S50-10Kw-220Vac-50Hz-Wind-Turb/p210/

http://store.altenergystore.com/Wind-Systems/Wind-Turbines-Electric/Grid-Tie-Wind-Turbine-Kits/WHI-500-GT-Whisper-500-with-Magnetek-Aurora-Grid-Tie/p2574/

Greg

My friend built a 2 kw windmill and they 3 phased. They used batteries to stabilise the output.

This is the dilema with windmills, too much or not enough. it is my belief that windmills should be used only to pump, when speed rpm doesn't matter , either water (or liquid matter) into a reservoir that will in turn stabilize the output with a water turbine. Depending on your location and your needs, you will be certainly find a way for combining few or many needs and possibilities at the same time. For instance, if you have a small water stream in your lot, it may be combined with the input of the windmill pumping water into a pond (like fishing ?)or pool (like swiming ?) or flower garden falls (adds value to your house and keeps the air clean). If you need drinking water, that pump can serv you well into the well as well ...

Another pump could be air. Build up air pressure into a tank and you have power to do things, many things. Remember that the old locomotives were powered by pressure. You could have your own cogeneration plant ... burn trash, wood, coal, methane (sceptic tank) , solar , etc and filter the particles with your garden falls compost ashes into the garden, poor concrete with ashes ...

So many possibilities. The key is to combine as many needs as possible, so that one builds less infrastructure (costly) for many uses.

Believe me, matchine 3 phases is not difficult even 40 years ago, with modern technology its probably a piece of cake!

I would even say personally that in large windmill power generators, its probably easier to manage AC than DC, whereas in small Windmills, DC is easier to manage than AC......personal opinion only.

But all he wanted to know was the name of a manufacturer of such AC equipment and only one of us has given him a name! Shame on the rest of us!! Including me......

Any e-mail me your address as I have some questions about name brand wind generators for home use. thanks Todd Glockzin U.S.A. glockzinheating@sbcglobal.net

talk to my friend

mike.vittori@tetrapak.com

he has all the scoop on this - tell him his "lunch buddy" recommended him.

Are you asking about the mechanical control of the wind generator orientation to the wind. That would depend on the style of wind mill. I had a regular three bladed prop on a horizontal shaft and a tail vane to control the propshaft direction relative to wind direction. The prop was taken out of the wind by mechanically adjusting the vind wave tail using a spring loaded cable. This was an old swiss design made by Elecktro and I doubt it's still in use. Most modern props are now using feathering blades. The hub mechanism is somewhat complex and relatively fragile compared to the wagging wind vane tail.

Modern composite materials also allow the use of flexing prop blades which in turn allow a much wider effective range of wind speeds. This seems to be the preferred approach of the Danish designs used in the Norht Sea.

regards

Elnav