As you know for the last couple of months I have been busy writing software for monitoring/logging data from my turbine and Xantrex XW inverter. I now have accumulated about 3 weeks of actual run-time data. I have been working with Xantrex and they have been an invaluable help in working out some issues. If interested more information can be gotten at
http://www.briery.com/wind_turbine/build_log7.html
It has all been a great learning experience! However along the way I realized that I had measurement problems, from bad analog current meter, irregularities in measuring Hz (rpm), as well as anemometer issues (averaging).
One by one I have been addressing them, but still working on making my own digital anemometer. So I still question wind speed.
Also along the way I realized that my wind turbine has a stall issue in that the generator overpowers the blades. To help I have installed a massive .6ohm, 6kw power resistor, this has helped the turbine in medium winds. I still have a bit of a stall issue, but I am also in a pretty good wind area, so better a bit stalled - than a bit loose - as the following numbers will show...
So I know that my turbine is under-performing, but I'm willing to live with it as it appears to have good high-wind survivability. Over the last couple of months we have has 48mph winds two times and once 58mph. Seems that when the wind really blows here that it is a very gusty wind, with huge bursts of high energy, a number of times I have seen output of 5-6kw!
With all explainations, here are some numbers:
Wind
Speed RPM Watts
------ --- ------
6 105 250
10 120 400
14 145 900
18 165 1400
-- -- --
34 240 4400
38 255 6400
You will notice one section not present, it is a gray area as with my anemometer averaging and wind gusting I can't get any good readings.
The top end is pretty apparent! At some point large gusts of wind have caused the turbine to begin to 'break away'!!
So far I have been present when these events have occurred and have manually shorted out my line resistor, that appears to get the turbine back under control and slow it down in quick order.
This is one reason that with the software that I am designing that I will have the ability to have the computer automatically switch out the line resistor for me.
I should add that I got the 17lb, 24" long, .62ohm 6kw power resistor from a guy named Nando, he used to be on this board but is nomore. If anyone is interested in purchasing one (less than $50) contact him at nando37@tx.rr.com
Once I finish up the interface to the anemometer I should be able to get more accurate instanttaneous wind speed measurements. I am working with a PicAxe chip, and will have a wireless ghz transmission that should be easily read for almost a mile...
Hope this helps!
Dan Lenox