Reducing wear on wind generator

[tonig123]

I was just sitting watching my generator spin under cut-in speed (low winds lately) and thought that it would be a good idea to break the generator until the wind speed gets to cut-in speed.

Using a PIC controller (like gizmos great data logger) it should be easy to have the generator shorted until the windspeed gets over cut-in speed.

This would make the generator spin only when its worth spinning, reducing wear on all the mechanical parts (bearings, etc).

¿Does this make any sense?

[scottsAI]

Hello tonig123,

Interesting idea!

Not much load on it then, but around here that may be 50% of the time.

Is nice to watch it spin, even if not producing.

Of course Now you will need along with the micro a separate device to measure wind speed. I plan on using pitch control, so have the micro.

Now I have something else to put on my list! to find an answer I can accept.

Have fun,

Scott.

[tonig123]

Yes, you would need an anemometer. Very simple to build and to interface to the PIC. Take a look at gizmos data logger.

[SamoaPower]

I fully agree. In fact, I've already incorporated this into my proposed pitch control algorithm. No sense in putting more wear on the machine than necessary. I would set it to average the wind data for about five minutes or so and start it up a little below cut-in to allow spin up time. I don't think you would want it starting and stopping for every little gust.

I found Scott's comment about needing an anemometer interesting. I thought all wind users had one of these.

Go for it!

[elt]

Or you could just let it go every few minutes and see what happens. I wouldn't think that you'd even need to wait for it to come up to a steady voltage ... I assume that the blade would accelerate faster in faster wind so you could just take two or three voltage measurements at a fix time interval, see the rate of increase in voltage and get an idea whether it was worth letting it spin up to full speed or not.

- Ed.

[DanG]

Contrairian opinion - All you're doing is designing in more complexity thus higher risks of unintended operation or failure, plus the parasitic load of maintaining relay logic and controller circuits isn't the best investment of your watt-hours.

Rotor bearings and seals need to be excercised to keep them lubed so properly adjusted and shielded from moisture and grit they should outlast the stator encapsulent and insulation on the wires. The free turning rotor tracking into low speed winds is zilch flex-moment stress on tower and furl bushing, the constant seeking helps displace moisture and may help keep accumulated grit ground fine enough to keep it from gougeing or scoring the furling bushings when real work gets done.

Anyhow - keep it simple principle applies doubly; if there isn't enough energy in the wind to make power passively make sure its spun up and ready for when it has by not 'overcontrolling', and not to power equipment 24/7 monitoring 'not enough' wind power.

~

[tonig123]

If you use a charge controller you are already having a load for logic and controllers. You could design a circuit that does charge controlling, data logging and low-wind breaking all with one PIC.

Anyhow, you've got a good point there, DanG.

You could always put a switch on this feature so you can turn it off and let it spin if you want.

[powerbuoy]

I believe that you might be over estimating the wear and tear in light winds, properly sized bearing can last a long time. I assume that you use a PMG?

Powerbuoy

[ghurd]

Me too.

Not sure how a good bearing for 20MPH winds would be harmed with rotation at 4MPH winds.

A hand held 3 foot prop, in both situations, would explain why I feel that way,

but it is dangerous.  Certainly not something I will recommend.

I was knocked off my feet in a gust under 20MPH, with a hand held 32"D prop.

If the bearing can not take the small vertical stress, it's probably not up to the horizontal stress.

Then again, I don't know about bearings.

G-

[paradigmdesign]

I agree.  Also, a rotor kept moving is a lot less likely to freeze up in the winter.    

I bet doing that will actually increase your cut in speed a little, because they will have to get the inerta all at once, once the coils let go to get the rotor spinning.

I don't think that the loads, ie. wear and tear is high enough at low wind speeds to justify that sort of device.

[scottsAI]

Hello SamoaPower,

Just down the street is an anemometer with a web page.

I check it daily if not more. Until I get my own wind gen that will do!

I looked at your three diary entries. Interesting.

I do very strongly believe in the Keep It Simple Scott:-)

I to like efficiency and not worried by complexity.

I have a 10kw wind turbine to design, with average 12mph winds.

Electric bill is $500/mo, expecting $100/mo savings. Goal is to spend less than $6K.

I started with an axial machine. Concluded not going to make it $ with any efficiency.

Current plans are to use 15+ HP induction motor as a generator back feeding the utility meter (netmetering) Battery is not large enough to store the wind gen output.

To use the induction motor requires pitch control. (for most)

To reduce ware, will be running a 24' blade at nearly fixed speed of 80 rpm. TSR will be adjusted based on the wind speed. Hope to get cutin at 5-6 mph with TSR 14, TSR 2 at 35mph.

Furling is done by Pitch control. Plan to always produce power even in 70 mph winds, TSR 1.

Have fun,

Scott.