Arc Flash Analysis in Wind Farms 1

[rockman7892]

I have recently come across a possible opportunity to perform and Arc Flash Analysis on a wind farm and wanted to see if there were others out there that have previously completed an Arc Flash analysis on a wind farm and if so what kind of modeling techniques were used?

Obviously in a wind farm that fault at any point in the sysetm will be a function both the fault current coming from the utility grid as well as the fault current coming from all the other wind turbine generators located on a given string. I know that some of these wind farms can have upwards of 500 or so wind turbines which I would see as a very cumbersome task to model each individual wind turbine in a sofware package for purposes of Arc Flash Analysis.

I am trying to think or reasonable asssumpitions or modeling techniques that can be utilized to reduce the amount of modeling necessary on the wind farm for arc flash analysis purposes. I realize that with Arc Flash we essentially want to find a maximum and minium arcing fault current at a given location in order to determine the worst case Incidnet Energy level resuling from the assocaited proective devicses based on these max and min arcing fault currents. With that said I am wondering if there are modeling assumptions that can be made in order to represent these maximum and minimum scenarios.

For instance rather than modeling each individual WTG can the generators be lumped inso some sort of lump sum contribution for a given string (obviously cable distance would be ingored in this case). For calcultions within individual wind turbines perhaps an infinite bus on the primary of the padmount transformer can be used to represnet the maximum case and then some other scenario for the minimum case?

I'm very curious to hear if others have had a similar experience and what approach or assumptions were taken.

Thanks

 

[wbd]

Hi,
Not sure what country you are in but here in the USA, this would be considered a utility like installation even if it is not owned by a utility. Therefore, it would be subject to OSHA 1910.269 regulations and a new 1910.269 was issued earlier this year which contains arc flash hazard assessments. OSHA states that the utility needs to make a reasonable estimate of the incident energy available.

I would think that you could reasonably lump some of the wind turbines together as nodes based on some sort of reasonable method (maybe a geographical distance) and then perform an analysis with different scenarios such as utility source only, utility plus 25%, etc. and see how much the incident energy changes.

 

[racookpe1978]

Be very aware that many wind turbines are 'auto-start/auto-synch" ... If the proper wind farm 'section" is not completely tagged out and isolated from ANY generated voltage, an "off' turbine in the group may suddenly come up to power and feed it the lines with ANY operator action or intervention or ability to prevent.

 

[crshears]

Depending on control sophistication, it may be possible for the WT farm operator to apply shutdown over-rides to specific WTGs to mitigate fault current infeed. Knowing that this can be done can greatly simplify arc flash analysis; actually doing it can be applied day-at-hand to reduce the short circuit capability at the point of work so as to comply with the regulations. Whether an electronic lockout will suffice for this purpose or if local manual lock-out and tag-out WTG disabling is deemed to be required is something to be decided locally.

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]