#1 2017-03-06 12:46:02

Clanker
Member
Registered: 2017-03-02
Posts: 7

Negative Wake Effects

Sometimes I see negative wake effects. Especially when looking at the production tab and showing results by sector. How should I interpret these?

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#2 2017-03-07 17:56:32

Morten
Administrator
From: DTU Wind Energy
Registered: 2009-11-02
Posts: 107
Website

Re: Negative Wake Effects

Hi Clanker,


If you select the single-wake page and display a crosswind profile of the velocity deficit you will usually see some undulations outside the main wake. A slight deficit (actully a speedup) next to the wake might be realistic, but it is hard to believe such effects further away so we think that the undulations are caused by a numerical problem in the progam. This undeciered 'model feature' might explain small errors in sector-wise AEP results. You are welcome to send a test case to WAsP support if you see errors are significant and suspect that something else might be wrong.


Cheers,
Morten

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#3 2017-03-08 11:06:02

Clanker
Member
Registered: 2017-03-02
Posts: 7

Re: Negative Wake Effects

Thank you for the reply Morten. That might be the explanation. I will experiment a little bit more. Also. I'm sometimes getting error messages when I try to open my workspaces in Fuga. Could you enlighten me on what they mean? The errors look like this.

Exception occurred in Fuga-64 'allWakesAndFarmAvail' routine while checking windfarm availability
Tlogger.stop>MemoryUsed>Range check error

or

Exception occurred in Fuga-64 'ComboBox2Change' routine
Tlogger.stop>MemoryUsed>Range check error

Among other routines(showCombinedWakeProfile, etc.)
All seem to be related to different routines, but they end in >MemoryUsed>Range check error.
Does this have to do with my computers RAM?

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#4 2017-03-08 13:31:27

Morten
Administrator
From: DTU Wind Energy
Registered: 2009-11-02
Posts: 107
Website

Re: Negative Wake Effects

This is a known bug in a routine gauging the memory use. It is a simple integer overflow and may happen even though you still have not used all the RAM memory. I already fixed it in the developer version.

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#5 2017-03-09 11:22:47

Clanker
Member
Registered: 2017-03-02
Posts: 7

Re: Negative Wake Effects

Ok. How do I get around it?

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#6 2017-03-09 11:50:55

Morten
Administrator
From: DTU Wind Energy
Registered: 2009-11-02
Posts: 107
Website

Re: Negative Wake Effects

You could try to reduce the memory usage following the Fuga help file section 'Further information>Fuga speed and memory usage'. The most important tip is that Fuga consider turbines with different hub heights as distinct turbine types, so it is a bad idea to specify individual hub height if these are on the order of a few centimeters.

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