How to get the list of Machine inertia from PSSE?

answered Jan 4 '16

danzg
11 ●1 ●2

Hi, instead reading the .dyr file you can retrieve the required values from internal dynamic data arrays. General idea is presented below (not the most elegant code but it serves its purpose). Hope this would help.

import psspy

# ------- SUBSYSTEM DEFINITION AND MACHINE SELECTION CRITERIA ---------
#         (a basic example shown here)
Sid=-1   # All machines
Flag=1   # Only in-service machines at in-service plants
ierr, Nmach=psspy.amachcount(Sid, Flag)           # get no of machines in the subsystem
ierr, iMbus = psspy.amachint(Sid, Flag, 'NUMBER') # get machine bus numbers
ierr, cMids = psspy.amachchar(Sid, Flag, 'ID')    # get machine IDs
iMbus=iMbus[0]
cMids=cMids[0]

fout=open('D:\Examples\Inertia.txt','w') # open a text file at desired location
savFn, snpFn = psspy.sfiles()
fout.write('MODEL: Load flow:     %s\n       Dynamic model: %s\n\n' % (savFn,snpFn))
fout.write(' BUS    NAME                GEN  MODEL    H (sec)\n--------------------------------------------------------\n')
for iM in range(0,Nmach):  # iterate through the list of machines
    ibus=iMbus[iM]
    genId=cMids[iM]
    ierr,busN=psspy.notona(ibus)
    iH=0  # resetting the intertia value index   
    ierr, icon0 = psspy.mdlind(ibus, genId, 'GEN', 'CON') # get initial CON address (index)
    ierr, genMdl = psspy.mdlnam(ibus, genId, 'GEN') # get generator model name
    genMdl=genMdl.strip()                           # remove blanks
#   Find absolute index iH in CONS array using relative CON index in the generator model and
#   previously found starting CON index of the generator model
#  (here shown only for the three most common models)
    if genMdl=='GENCLS': iH=icon0                           
    if (genMdl=='GENSAL')|(genMdl=='GENSAE'): iH=icon0+3    
    if (genMdl=='GENROU')|(genMdl=='GENROE'): iH=icon0+4
#   Get value from CONS array corresponding to the generator inertia
    ierr,H=psspy.dsrval('CON', iH)
#   Write output to the file    
    fout.write ('%6d  %12s   %2s  %6s  %6.3f\n' % (ibus,busN,genId,genMdl,H))

print ' *** END OF FINDING MACHINE INERTIAS ***'
fout.close()

answered Dec 7 '15

SqFKYo
126 ●4

Based on what you get as answers, I'd assume that:

1. You haven't set a bus subsystem, that's why you get error '2' from your first print.
2. The machines are modelled as regular machines instead of induction machines, as when you try to list all of them, you get none.

Solution: I'd assume that the inertia constants are inside the .dyr-file instead of the .sav case. Since amachreal doesn't allow intertia as the search string, I'm not sure if you can access that data directly from PSS/E, but you could iterate through the .dyr text file to find the inertias?