How to estimate the maximum asymmetric short circuit current?
Hi folks,
I want to determine the maximum asymmetric short circuit current due to a bus fault at a particular bus in my saved case. How do I determine this using the PSSE API?
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Hi folks,
I want to determine the maximum asymmetric short circuit current due to a bus fault at a particular bus in my saved case. How do I determine this using the PSSE API?
Running a short circuit analysis and getting the results back can be difficult with the PSSE API. The documentation doesn't have any examples, and the API is a bit confusing. Here is how to do it:
ASCC_CURRENTS
ascc_currents
in the pssarrays
module will run the short circuit analysis and return the results in a custom made Python type that PSSE refers to as rlst
.
# this script assumes you have already initalised PSSE and loaded a saved case.
import pssarrays
# create a subsystem of buses you will apply the fault to.
DOWNTOWN_SID = 1
psspy.bsys(sid=DOWNTOWN_SID, numbus=2, buses=[2001, 2002])
results = pssarrays.ascc_currents(sid=DOWNTOWN_SID,
all=0,
fltlg=1, # report on line to ground faults.
flat=0) # use prefault voltage from working case
This code will run a line to ground fault on two buses 2001
and 2002
and store the result in the scfilename
file. We don't use flat start conditions, so the pre-fault voltage is the same as the one in the solved case.
Lets unpack the results variable to see what is inside:
# get the phase A current for this line to ground fault
phase_a = [i.ia for i in results.fltlg]
# and match the phase currents up against the faulted buses
fault_currents = zip(results.fltbus, phase_a)
print fault_currents
That final print statement should show something like this:
[(2001, (30.4 + 12.j) ),
(2002, (30.1 + 11j) ]
You asked about how to find the maximum. There are a number of things that contribute to a maximum fault level:
There are a few other things to watch for that will increase your fault currents unrealistically. If you model your SVC units as a synchronous condensor (like we do) then you need to replace it with an equivalent capacitor bank. SVC units behave like a capacitor during short circuits, not like a spinning machine.
I don't have a copy of PSSE here with me (and I wont for a few months). You should check that the code to get phase_a
works. Let me know if it doesn't so I can update the answer with working code!
Jervis, have you attempted to generate any graphical results from an ASCC routine? The PSSE api doc shows command ASCC has a parameter scfile which creates scfile. The PSSE api doc then shows command ASCC_SCFILE can read this file into memory to enable displaying ASCC results onto slider diagrams.
Asked: 2012-06-17 20:47:10 -0600
Seen: 4,544 times
Last updated: Jun 18 '12
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