Could you also look at the wind speed STD per direction? May be south wind has more gusts and the furling is too slow to respond. We here use an overhang value of about 1.5-1.8 of the offset value and it allows for rapid response of the furling and a slower return.
It seems that the main difference is in the furling region between 10 to 16 m/s. In the south direction there is less effect of the furling and at 16 m/s the power increases again. This happened to us here and was corrected by allowing the tail to be parallel to the blade plan (change in the high stop). AS for the furling difference it could be from high tension of the wires in one direction of rotation or some unexplained friction in the yaw bearing in one direction.
Yes it’s an issue with furling that i am highlighting. I am happy with performance generally. The main feature of the south wind is the fact that it blows up a steep slope and I suspect this is the cause but I don’t know the actual mechanism. The reason I suspect the slope is causative is that Bergey windpower have the same experience.
The guy wires must be the same tension in both directions or the tower would move to equalise the guy tensions. Of course it’s always tighter on the windward side. In both cases the tail lifts as normal only it lifts sooner and higher with the north winds allowing less power output.
I will take a look at the turbulence theory. I do have standard deviation data but I will have to dig it out. I think I threw it out of the spreadsheet.
Could you also look at the wind speed STD per direction? May be south wind has more gusts and the furling is too slow to respond. We here use an overhang value of about 1.5-1.8 of the offset value and it allows for rapid response of the furling and a slower return.
It seems that the main difference is in the furling region between 10 to 16 m/s. In the south direction there is less effect of the furling and at 16 m/s the power increases again. This happened to us here and was corrected by allowing the tail to be parallel to the blade plan (change in the high stop). AS for the furling difference it could be from high tension of the wires in one direction of rotation or some unexplained friction in the yaw bearing in one direction.
Thanks Noam, Happy New Year
Yes it’s an issue with furling that i am highlighting. I am happy with performance generally. The main feature of the south wind is the fact that it blows up a steep slope and I suspect this is the cause but I don’t know the actual mechanism. The reason I suspect the slope is causative is that Bergey windpower have the same experience.
The guy wires must be the same tension in both directions or the tower would move to equalise the guy tensions. Of course it’s always tighter on the windward side. In both cases the tail lifts as normal only it lifts sooner and higher with the north winds allowing less power output.
I will take a look at the turbulence theory. I do have standard deviation data but I will have to dig it out. I think I threw it out of the spreadsheet.
cheers
Hugh
Iwas probably not very clear. I meant the electrical wire tesion…
OK I get it you mean the wires were maybe twisted inside the tower, but no they are not in this case.