Ellipses

Hey Nick,

Have you noticed that the turbine seperation ellipses in openWind don't match the ellipses in other programs? 

Any chance you could put in a feature that allows us to export your ellipses?

Thanks!

Alicia

Hey Alicia,

I don't use any other software than openWind

What do you mean? In openWind, each turbine maintains it's own separation criteria regardless of the separation criteria of other turbines around it. I have had requests to take the average but that I'm not sure how to do that and still allow each site to set it's own separation criteria.

I don't think coding up an export for the ellipses would be hard but I'm interested to know if you think openWind is performing correctly or not.

Nick

Hey Nick,

I noticed it on a project that was optimized in openWind and then exported to another program for energy capture (due to specific requrements in a particular RFP).  In openWind, the site was optimized for a 3D x 6D spacing, and everything was peachy keen.  When we set it up in the other software with the same settings, the layout was no longer valid because of turbine spacings.  So, we checked the spacings with an ArcGIS extension (military analyst), as well as an internal code that we used prior to getting military analyst, and the ellipses from both of those GIS tools seemed to match up better with the other software than with openWind.  I'm not going to gander as to which algorithm is correct, because the other 3 could just happen to use the same code.  But, from our point of view, we'd need to take the more conservative of the assumptions and that is not openWind in this case. 

That being said, the ellipses aren't really a hard setback anyways in most cases, it's about turbulence and wake.  But we do work with one manufacturer that locks into very specific spacing requirements, and it is also sort of necessary to make sure we aren't using a wake model at distances for which it wasn't intended.

I can set up a screen share so I can show you what I mean if that would help.

Alicia

Hi Alicia,

Yeah I'd like to see it please. When I measure them they seem right. Ellipses are not so complicated (which makes me even dumber if I've got this wrong) and so its hard to imagine what the difference is. I treat the turbine location as a point. Does the other software treat it as a circle as this would make a difference. Also, the ellipses I draw have no safety factor. They can nudge right up to each other.

Nick

Hi Nick!

Good seeing you at AWEA!  Glad we figured this out!

Talk to you soon!

Alicia