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Weird bug in user defined contingency list

asked 2014-08-21 13:02:40 -0500

ypwang gravatar image

Hi everyone,

I came across a very weird bug in my contingency analysis, where I created several two-branch contingencies in the .con file to feed into "ACCC_with_dsp_2”. I got message as below:

 Processing contingency "BRANCH 201-204(1)" (#1 of 1):
 OPEN BRANCH FROM BUS 201 [HYDRO       500.00] TO BUS 205 [SUB230      230.00] CKT &1
 *** Successful solution not achieved: Iteration limit exceeded ***
 Largest mismatch is     172.19 MW or Mvar at bus 205 [SUB230      230.00]
 Total mismatch is       749.22 MVA

While, the actual content (written by one of my function in order to exclude those radial lines) of my .con file is as follows.

/PSS(R)E 33
COM
COM CONTINGENCY description file entry created by PSS(R)E Config File Builder 
COM

CONTINGENCY 'BRANCH 201-204(1)'
OPEN BRANCH FROM BUS 201 TO BUS 204 CKT 1 
END 

END

Note that this test is based on "savnw.sav" case.

So the ACCC modifies the second toBusId from 204 to 205 and change CKT number from to "&1". I am confused because, in my defined subsystem (area1 and area2 with bus base kv>=10), branch 201 - 205 (1) doesn't exist and 201-204 does exist. My confusion are: 1) why does ACCC change 204 to 205? 2) why change ckt (circuit id for parallel branches) from '1' to '&1'

I didn't know ACCC actually can recognize '&1' as a valid circuit id. And I tried to replace the original command with "OPEN BRANCH FROM BUS 201 TO BUS 205 CKT 1 " and ACCC complained that " branch not found", which makes sense since there is no such branch in the subsystem. While when I experiment changing the command to "OPEN BRANCH FROM BUS 201 TO BUS 205 CKT &1 " and ACCC recognize it and process successfully.

Could any one see what is going on here?

Appreciate it.

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answered 2014-08-22 02:22:05 -0500

rimux gravatar image

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.

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answered 2014-08-22 19:15:50 -0500

jconto gravatar image

A multisection line is a group of branches in series representing a breaker-to-breaker link of branches. Branches internal to the multisection line cannot be opened in practice, instead the whole breaker-to-breaker link will have to be opened during maintenance or any other kind of event. The character '&' is reserve for the id of these multisection lines. member branches are define in the branch section with standard id characters.

It seems ACCC recognize that an internal branch is called to be outage therefore 'reverts' to outage its corresponding multisection line. Being a grouping of lines, you can delete such entry from the multisection table, without changing the true network topology, allowing member branches to be evaluated in explicit contingency definitons. I do not think this feature is a bug.

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Asked: 2014-08-21 13:02:40 -0500

Seen: 865 times

Last updated: Aug 22 '14