Perform frequency scan using Thevenin impedance

Hello everyone,

My question here lies on the method to change the parameters corresponding to the interested frequency: 1. Export to raw then change parameters corresponding to the interested frequency in raw. Then import to PSSE and get Thevenin impedance. 2. Change the parameters in PSSE, then get Thevenin impedance.

I have tried the 1st one, but it took about 20s to execute a scan (one N-0 loadflow case of about 500 buses, scan in range of 5 to 50, step 0.5). It seems forever when you want to do N-1 and N-1-1 analysis.

Which way is better, in your opinion? Do you have another way to do the job? Anyone has a benmark or test system to validate the results?

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Cao Huy

asked 2018-04-19 03:22:32 -0500

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Use parallel processing. Using the multiprocessing module, 'creating' the fi-cases (i=5, 50, 0.5) or run a frequency scan for one contingency assigned to one CPU, and so on. Increasing the frequency step size from 0.5 to 1 would also reduce overall study time.

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jconto

answered 2018-04-20 14:38:15 -0500

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Thanks for your reply. By creating fi-cases first instead of for each iteration will reduce a lot of time. I will also check for multiprocessing, havent done a parallel running before. Of course I'll give it a try.

Cao Huy (2018-04-22 22:56:17 -0500) edit

Check the posting "Python Parallel Dynamics Simulations." Also download my tool MPjobs that allows multiple runs of psse in parallel.

jconto (2018-04-24 09:20:24 -0500) edit

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PSSE is a tool for conducting power systems analysis at the fundamental frequency, usually 50Hz or 60Hz.

It seems that you are looking to do a frequency scan, which is typically part of a harmonics analysis study. Adjusting the base frequency and doing several calculations in PSSE will give you a frequency scan, but it will not be a very accurate one since it will not take into account the distributed parameter nature of overhead lines and cables.

If you want to do harmonics analysis then I suggest that you use a different software package.

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jfconroy

answered 2018-04-23 01:42:40 -0500

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Changing the base frequency is not a solution. The only way is to recalculate all impedances and susceptances to the new frequency, as described above. Frequency scan in the sub-synchronous frequency range can be done in PSSE, using the simple R,X,B model.

perolofl (2018-04-23 02:44:02 -0500) edit

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Perform frequency scan using Thevenin impedance edit

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