rimux's profile - activity

PSSE can do a lot of things - load flow, dynamics, contingency, OPF, short circuit etc. Also it is not clear do you have your network in psse format already - if you need to build your network from scratch - could be not easy task for beginner as well. And PSSE manuals are really large...good luck:)

And when saving raw files, select option "Configure RAW file to Add to working case"

I have created for myself simple solution for automatic creation of sld diagram containing necessary buses placed in the right places. Save following gif file and change extension from gif to zip, inside there are one excel file and one python file. Excel template is for preparing list of buses containing x and y coordinates for each bus. On "buses" sheet put bus numbers in the cells where approximately they should appear on your sld file. Then run macro "PreapreForPython" (to do that you will probably need to enable Developer tab). than copy-paste from another sheet list of buses into python just after "buses=" line. Than open in psse blank sld and run that python script. All buses will be more or less in right places. Of course this thing could be improved, feel free to do that, just don't forget to put better solution here :)

PSSE_SLD.gif

There are no API for building ".mon", ".con", ".sub", but this is text files so would be not big deal to write some python code for doing that. Or you can use excel, I for example have excel template that creates lists of branches in right format for .con and .mon. Regarding second question, I think you should check output results when using the same .dfx and not the same, and you will know is there any difference or not. I think if you are not changing grid topology (connecting/disconnecting branches and other equipment you have described in .con and .mon) there should not be any difference, because you should have correctly solved case before running contingency routines.

You can do it in Excel, 2000 bus bars are not too much for excel for sure :) And from Excel copy those two columns of old/new bus numbers into .trn file in any text editor.

Use standard PSS/E functions. From top menu:

Power Flow -> Renumber Buses -> By Bus Number

Just prepare .trn file which format as far as I remember is very easy:

'old bus number'  'new bus number'

R = branchrx.real
X = branchrx.imag

from API manual:

ierr, rval = brnmsc(ibus,jbus,ickt,string)
’P’ Branch MW flow at the IBUS end of the branch.
’Q’ Branch Mvar flow at the IBUS end of the branch.

You can get P and Q at the desired branch end just by placing correct bus number into ibus place. Formula for MVA:

S=sqrt(P^2+Q^2)

Nice solution from amaity.

Another possibility - use abrncount, abrnint and other API commands for retrieving all branch data for defined subsystem at once. Just use right option FLAG, e.g. FLAG = 1 for only in-service non-transformer branches and FLAG = 5 for only in-service two-winding transformers.

Also if need to check just one branch if it is line or transformer - just get the base voltages form both sides of a branch (by using psspy.busdat(bus,"BASE")) and compare them - if voltages are different - this is transformer.

In savnw.sav 201-204-205 is a multi-section line, so for PSS/E it is the same are you disconnecting 201-204 or 201-205. But I don't have experience with multi-section lines and I newer use them so you need to read PSS/E manual if you want to learn more. As I can see in savnw.sav bus 201 has voltage 500 kV, bus 204 also 500 kV but bus 205 has 230 kV, so this should be power transformer. I would better use normal way of modelling power transformers.

I tested and updated my code and now it should work. I just forgot that command tree needs some special behavior.

Once I also had the same problem with acccwithdsp3, I solved it by using the accc command insted - it works just fine. But you can try also acccwithdsp2 or acccwithdsp - may also work.

I think that after tripping of one generator during ACCC process generation from lost generator would be replaced by increased generation from swing bus, so balance between generation and load in the whole system will be correct and you should not get "blown up" type problem. One fast solution I can propose to you is to try to set up swing bus (type 3 instead of 2) that it should be or the biggest unit in your system or some big hydro unit used to be fast reserve source in your system. You can have many swing buses in the system, e.g. one per area.

How to change production from all generators proportionally during ACCC process I didn't try to do by myself, but maybe you should start to investigate if it is possible not from analyzing API commands in python but trying to do this directly in PSS/E. In ACCC dialog window I see option ''Dispatch mode" and it has options "Subsystem machines (Reserve)" and "Subsystem machines (Pmax)". Maybe this is what you are looking for. From documentation I found description for e.g. "Pmax" option as following:

Participating machines are connected to dispatch subsystem buses and have positive active power generation. Each machine's participation factor is its maximum active power generation with positive values. If a Unit Inertia and Governor Data file is specified, maximum machine active power limits are taken from it; otherwise, the maximum machine active power limits in the working case are used. PT is adjusted by the rules discussed in Dispatch Mode of Machine Reserve.

So you should go and dig deeper and find in documentation about format of Unit Inertia and Governor Data file mentioned before. If you will find that it works, than in python you will need probably acccwithdsp_3 (for PSSE 33) command.

Seems that you are right, contingency list contains even those branches disconnection of which leads to island.

Of course, would be nice that accc_violations_report would do output not only into text report but similar output like accc_solution. Maybe we should write to PSSE support proposing to include such improvement, shouldnt be big deal for them to implement this into next psse version I think.

I am fetching monitored elements by using api command accc_solution, e.g.: sm=pssarrays.accc_summary(accfile=acc) for i in range(len(sm.colabel)): CL = sumry.colabel[i] r=pssarrays.accc_solution(accfile=acc, colabel=CL, stype='contingency', busmsm=bm, sysmsm=sm) mva = r.mvaflow

Also I am not sure you really need to filter those radial lines as psse DFAX command will automatically (I think so, will check this tomorrow) remove those contingencies that leads to formatting islands in the system.

Island means - there are bus or buses which do not have connection to any type 3 bus (swingbus).

I suggest you not to use python IDLE if possible as it is very simple and not very programming-friendly enviroment. I would recommend to use PyScripter or Notepad++, both of them are free and much better shells for writing in python. In PyScripter you can terminate running program by pressing Ctrl-Alt-F9 ('Abort debugging'). In Notepad++ for running python programs you will need to install plugin NppExec and run python scripts by pressing F6 (for the very first time you will need to enter this line for make it work: C:\Python27\python.exe "$(FULLCURRENTPATH)" ). After program starts, if you'll press F6 again "Terminate" button appears and you can kill active process. Try this and you will never ever want to come back using native python IDLE :)

I would suggest to go through a list of branches and disconnect them one by one. After disconnection of the branch, check if there are no islands - if you will get an island this means that branch is radial. e.g.:

import psspy

branches=[[101,102,'1'], [201,202,'1']]

psspy.progress_output(6,"",[0,0])

List=[]
for b in branches:
  ierr, status = psspy.brnint(b[0], b[1], b[2], "STATUS")
  if ierr==0 and status==1: #branch is on
    ierr = psspy.branch_chng(b[0], b[1], b[2], 
               [0,_i,_i,_i,_i,_i], [_f,_f,_f,_f,_f,_f,_f,_f,_f,_f,_f,_f,_f,_f,_f])   
    if ierr==0:
      ierr, n = psspy.tree(1,0)
      if ierr==0 and n>0: #island detected
        # b is radial branch...
        print 'branch',b[0], b[1], b[2],'is radial'
        ierr, n = psspy.tree(2,-1)
      else:
        #branch is not radial 
        print 'branch',b[0], b[1], b[2],'is not radial'
        List.append(b)              
      ierr = psspy.branch_chng(b[0], b[1], b[2],
                 [1,_i,_i,_i,_i,_i],[_f,_f,_f,_f,_f,_f,_f,_f,_f,_f,_f,_f,_f,_f,_f])  
#List will contain only non-radial branches (and only with status=on)

psspy.progress_output(1,"",[0,0])
print 'Non-radial branches:',List

Regarding 1st question - just write in the top of A.py:

import B
import C

than if you have e.g. in B.py some function1, you can reach it in A.py :

B.function1()

Check the API.pdf manual file - abusreal command will give to you results from all buses at once.

#List of generatorts for investigation:
Gen=[[bus1,id1],
     [bus2,id2],
     [bus3,id3]] #and so on

#Loop through all generators:
for g in Gen:

  bus=g[0]
  id=g[1]

  #remember initial generation:
  e1, Pold = psspy.macdat(bus, id, 'P')

  #getting generator Pmax:
  e2, Pmax = psspy.macdat(bus, id, 'PMAX')

  #changing generation to Pmax
  e3 = psspy.machine_data_2(bus,id,[_i,_i,_i,_i,_i,_i],[Pmax,_f,_f,_f,_f,_f,_f,_f,_f,_f,_f,_f,_f,_f,_f,_f,_f])

  e4 = psspy.fnsl() #solving

  #some code here - doing something, output results, etc.
  #...

  #restore initial generation:
  e5 = psspy.machine_data_2(bus,id,[_i,_i,_i,_i,_i,_i],[Pold,_f,_f,_f,_f,_f,_f,_f,_f,_f,_f,_f,_f,_f,_f,_f,_f]) 

  e6 = psspy.fnsl() #solving again

  if (e1+e2+e3+e4+e5+e6)!=0: print "got some errors ! ",g

Hi, I am not sure I understood the problem you are facing. This code should be run from within PSSE - just open PSSE, open desired sav, open python program with e.g. notepad++, change bus numbers in buslist (and add more), in psse create new empty diagram, and "run automation file". Thats it. About importing buslist information from excel - thats another story

I am doing like this:

from win32com.client import Dispatch
xlApp = Dispatch("Excel.Application")

def XLSReadValue(xbook,xsheet,cell,x,y): #x,y - offset from cell
  value = xlApp.Workbooks(xbook).Sheets(xsheet).Range(cell).Offset(x+1,y+1).Value
return value

def XLSWriteValue(xbook,xsheet,cell,x,y,value): #x,y - offset from cell
  xlApp.Workbooks(xbook).Sheets(xsheet).Range(cell).Offset(x+1,y+1).Value=value

Than, if I want to get from excel value from cell A1:

n=XLSReadValue('book.xls','sheet1','A1',0,0)

try to use function str, e.g.

print str(u'R3')

gives for me result 'R3'

if you have list of the lines, all currents from them you can get very easy:

lines=[[5001,5013,"1"],
       [5001,5035,"1"]] #put here as many lines as you want

l=len(lines)
for i in range (l):
  error, amp =  psspy.brnmsc(lines[i][0],lines[i][1],lines[i][2],"AMPS")
  if error==0:
    print str(i+1)+". Line: ",lines[i][0],lines[i][1],lines[i][2]," : ",round(amp,2)," A"
  else:
    print str(i+1)+". Line: ",lines[i][0],lines[i][1],lines[i][2]," : ","error in brnmsc"

I got the same in psse32.
I see 2 solutions for that: use not filled busbars - in this case printing is ok. Or use export to jpg - if quality of the picture sutisfy you. And of course - write email to psse support - they can make patch for psse32 to fix that issue.

I am not sure what problem did you get running my program, it runs on psse 32 just fine. By the way, I am using this program in connection with excel - in one excel sheet I am putting bus numbers in different cells that corresponds aproximately places where they should appear on sld diagram. Later run little excel vba code that generates buslist for the python program. Formulas for x and y coordinates are simple: x=(cell column number)x1.5 , y=-(cell raw number)x1.5 . Constants 1.5 can be different - depends what distance between buses in the diagram you need.