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Ph. Aupetit

Post subject: IEEE 1584 downstream a power unit with full converter Posted: Thu Apr 08, 2021 7:46 am 

Joined: Thu Nov 26, 2020 2:45 am Posts: 8 Location: France

Hello all,
In IEEE 1584, the arcing current and the reduced arcing current are calculated from the bolted shortcircuit current to take into account the arc impedance. This method is relevant when the different sources supplying the shortcircuit are voltage sources.
But what about when the one or one of the sources feeding the shortcircuit is a power station unit with full size converter (for instance large UPS or PV or wind power station unit with full converter)? In this case, for the calculation of the shortcircuit current (see IEC 609090_2016), the source is modeled in positivesequence system by a current source. The value of the shortcircuit current is therefore independent of the downstream impedance, in particular of the arc impedance.
My question is then the following: is it relevant to use the IEEE 1584 method when one of the sources feeding the shortcircuit is a power station unit with full size converter?
Thank you for your contributions on this topic. Best regards
Philippe Aupetit Trace software International


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Jim Phillips (brainfiller)

Post subject: Re: IEEE 1584 downstream a power unit with full converter Posted: Fri Apr 09, 2021 8:14 am 

Plasma Level 

Joined: Mon Sep 17, 2007 5:00 pm Posts: 1575 Location: Scottsdale, Arizona

Great question! Looking at the scope of IEEE 1584, it is the model for calculating incident energy, arcing current, and working distance  very limited. The question is often raised: How do you model this source, that source, etc. We always came back to: you provide a bolted short circuit current and other variables and that's it. How you derive those values is not addressed within IEEE 1584.
I coauthored an IEEE paper several years ago comparing ANSI and IEC short circuit calculation methods and how it might affect IEEE 1584 results. Although most results tracked closely, as you might expect if the calculated arcing current was close to a transition from instantaneous to time delay, different methods could have an impact on the arc duration and incident energy.
So, IEEE 1584 is the model for incident energy etc. but it does does not address methods for determining the bolted fault current or clearing time.
Hope that helps clarify!


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Ph. Aupetit

Post subject: Re: IEEE 1584 downstream a power unit with full converter Posted: Wed Apr 14, 2021 6:09 am 

Joined: Thu Nov 26, 2020 2:45 am Posts: 8 Location: France

Thanks Jim for your response, your opinions and comments are always valuable.
Unfortunately, I do not know enough about the ANSI standard to appreciate precisely the differences in the calculation of shortcircuit currents with the IEC standard.
But, notwithstanding the standard for calculating shortcircuit currents, my question is that if the source feeding the shortcircuit is a current source (for example power station unit with full size converter), I would tend to think that the arcing current should be taken equal to the bolted shortcircuit current as the shortcircuit current is then independent of the arc impedance. But what, in that case , of the reduced arcing current ?
Philippe Aupetit Trace software International


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