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My 17' Turbine so far
Boss:
Oh BTW where are you located, generally
SparWeb:
Hi Nekit. Isn't it great to see it come alive!
Your 2nd video catches some funny noises and I bet you're curious about that.
Two things: Is there any play in the yaw mount / can rock it slightly on the tower stub? If so then vibrations from various sources can resonate with this freedom of motion. It's not fatal and not even likely to be a problem, but you may see some wear on parts after a few years. Since you have a rather complex mounting system, I would be concerned about other parts being loose (tail hinge). It looks like your tower is a jiffy to lower so this might be easy to inspect. Considering how thoroughly everything's been done on your system, I rather doubt anything was missed.
The other thing is the electrical start-up conditions in the electrical system. Since you've got an Aurora I don't know if this is 100% applicable. Mine makes the same noise at cut-in speed and it seems to be caused by rapidly opening and closing the rectifiers. Let me tell you about why (I believe) it makes noise on my system, and you tell me if that is relevant on an Aurora grid-tie. The AC voltage increases with speed, and at cut-in, only the peaks are high enough to open the diodes. So you get very short "ON" periods where the diodes let current flow on any given phase briefly. The momentary ON is a higher load (torque) than the intervening times before the next phase voltage rises enough to switch ON. These torque pulses cause a similar growling noise. On mine, I find it is louder in Star than when phases are individually rectified, but the noise is there just the same. Only at cut-in.
Hope that helps!
nekit:
--- Quote from: SparWeb on July 03, 2011, 05:48:40 PM ---Hi Nekit. Isn't it great to see it come alive!
Your 2nd video catches some funny noises and I bet you're curious about that.
Two things: Is there any play in the yaw mount / can rock it slightly on the tower stub? If so then vibrations from various sources can resonate with this freedom of motion. It's not fatal and not even likely to be a problem, but you may see some wear on parts after a few years. Since you have a rather complex mounting system, I would be concerned about other parts being loose (tail hinge). It looks like your tower is a jiffy to lower so this might be easy to inspect. Considering how thoroughly everything's been done on your system, I rather doubt anything was missed.
The other thing is the electrical start-up conditions in the electrical system. Since you've got an Aurora I don't know if this is 100% applicable. Mine makes the same noise at cut-in speed and it seems to be caused by rapidly opening and closing the rectifiers. Let me tell you about why (I believe) it makes noise on my system, and you tell me if that is relevant on an Aurora grid-tie. The AC voltage increases with speed, and at cut-in, only the peaks are high enough to open the diodes. So you get very short "ON" periods where the diodes let current flow on any given phase briefly. The momentary ON is a higher load (torque) than the intervening times before the next phase voltage rises enough to switch ON. These torque pulses cause a similar growling noise. On mine, I find it is louder in Star than when phases are individually rectified, but the noise is there just the same. Only at cut-in.
Hope that helps!
--- End quote ---
Thanks for the info. I think your on track with the noise issue, but I think it's the aluminium cover that I made that goes over the slip rings. I'm going to bring it down and add some rubber and some other tweaks.
As for the startup, that makes sense. I'll have to watch it and see if that's the case over time.
Thanks
halfcrazy:
My neighbors 17 ft machine was doing the same growling noise at cut in on the Classic. We bumped the first two steps of the power curve up a few volts and that made it cut in a little later maybe 1mph? This basically eliminated the growl. We where originally trying to cut in around 4-4.5 mph I think that may just be to low now it is closer to 6 mph. I have talked to people that have had issues with towers resonating at a certain power output say 1000 watts and they did the same thing with the Aurora inverter they tuned around that spot by making one step a little high and letting the turbine free up a bit there.
nekit:
Here's the power curve I am currently using. This was compiled with the help of Rob Becker's info and some math crunching on my own. Seems to be working ok so far, but winds have been pretty low since my turbine went up. Time will tell.
Wind mph Wind (m/s) Watts Rotor RPM Hz Unloaded AC I Phase Loaded AC P Loss P Out Eff DC Volts MPPT Watts Out MPPT
4.48 2.0 30 44 5.9 58 0.3 57 0 30 99% 75 0
5.6 2.5 59 55 7.4 72 0.5 71 1 58 99% 93 30
6.72 3.0 102 66 8.9 86 0.7 85 2 101 98% 111 81
7.84 3.5 163 77 10.3 101 0.9 99 3 159 98% 129 151
8.96 4.0 243 89 11.8 115 1.2 113 5 237 98% 147 245
10.08 4.5 346 100 13.3 129 1.5 126 9 337 98% 165 365
11.2 5.0 474 111 14.8 144 1.9 140 13 461 97% 183 513
13.44 6.0 819 133 17.7 173 2.7 167 27 792 97% 219 911
15.68 7.0 1301 155 20.7 201 3.7 194 50 1251 96% 254 1461
17.92 8.0 1942 177 23.6 230 4.9 220 86 1856 96% 288 2188
20.16 9.0 2765 199 26.6 259 6.2 246 137 2628 95% 322 3114
22.4 10.0 3793 221 29.5 288 7.6 272 209 3584 94% 356 4261
24.64 11.0 5049 243 32.5 316 9.2 297 306 4743 94% 389 5651
25.536 11.4 5620 252 33.6 328 9.9 307 353 5267 94% 403 6280
Sorry Chart gets a little messed up when posted.
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