Power flow mismatch calculation fdns

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Hi, I have a question about power flow mismatch calculation in psspy when I use this code psspy.fdns and the IERR = 4 "buses in island(s) without a swing bus; use activity TREE". I am using the following code for power flow mismatch calculation. It is wondering that when the IERR = 4, I also get some value for mva however I don't know what this value is and how it is calculated! I appreciate your sharing your experience with this issue.

psspy.fdns([0,0,0,1,1,0,99,0]) mva = psspy.sysmsm()

asked 2023-02-19 13:38:36 -0500

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The system mismatch is calculated from the actual values of bus voltages (magnitude and angle).

The solution with FDNS is aborted since there is at least one island in the network.

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perolofl

answered 2023-02-20 03:08:45 -0500

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The mismatch value from sysmsm should be approximately less than 10. For a small network, the value is often less than 1. For a large network (thousands of buses) up to 5 might be common. If you get a value in the thousands or greater, the loadflow solution is very bad. To me, it is very good practice to consider the system mismatch to check that the results are valid.

If you are getting the message to run TREE, then you need to run TREE to switch off the isolated buses before running a load flow.

Alex P

answered 2023-02-20 09:21:51 -0500

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Power flow mismatch calculation fdns edit

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