How to perform power flow after network reduction with SCEQ?

asked 2019-05-10 11:10:50 -0500

drsgao
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Dear all, I found this very useful post for network reduction: https://psspy.org/psse-help-forum/que...

The problem is that since it needs to convert the generator and loads to perform SCEQ, how do you later do a power flow with the reduced network?

Network reduction in PSSE is becoming a headache for me. I need to make sure the fault level at the boundaries remain more or less similar after the reduction while making sure the active power flows are more or less the same. I have done this manually before and I am trying to use PSSE's built in feature to automate it. For my applications, other reductions do not seem to be able to the job since the fault currents after reduction are very different from before.

Any idea? Thanks a lot

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answered 2019-05-11 02:50:38 -0500

perolofl

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Is is just to write the write a RAW-data file of the whole converted network and read the file to create a new case. The generators will now be "unconverted".

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Hi, thanks for that. It kind of work, but now after reduction, the power flow cannot converge and it is always blown up after like 2 iterations. Any idea how to solve it?

drsgao ( 2019-05-13 05:02:57 -0500 )edit

Look för large shunts and loads at same bus with opposite sign. Test to simplify by merging them together.

perolofl ( 2019-05-13 09:19:54 -0500 )edit

Hi, I tried that and did not succeed. Now I think maybe there is more to do with the "Classical fault assumption" thing. Since once I set the fault condition to that, in the original network, the case cannot converge. And it seems like this setting would break the case and it non-converge.

drsgao ( 2019-05-13 12:31:19 -0500 )edit

Hi, try to look for equivalenced branches having very large impedance. When no current is flowing in the equivalenced branch, you can remove it and re-run the load flow.

ffl ( 2019-05-16 21:41:41 -0500 )edit

The network prepared with SCEQ cannot be used for load flow calculations since classical fault assumptions removes the load.

perolofl ( 2019-05-17 00:41:19 -0500 )edit

Thanks! So, if I want to do both load flow and fault level studies after the reduction and maintain similar levels of load flow and fault levels on key buses, and then perform dynamic studies, do I have to manually reduce the network?

drsgao ( 2019-05-17 04:04:51 -0500 )edit

You can first do a load flow reduction of positive sequence system with EEQV. Then reduce the original network with SCEQ in order to get equivalent generators, representing the Thevenin impedance of the reduced network in all three sequences. Then insert those generators in the EEQV network.

perolofl ( 2019-05-17 12:41:34 -0500 )edit

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How to perform power flow after network reduction with SCEQ?

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