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Start by
Bill Swingle, P.E.
08-03-2014 11:42 PM

Transient Stability study

A client just requested the price to perform a transient stability study. For a low voltage system at a building.

Well, I've never done one of these but I THOUGHT they were intended for medium and high voltage systems.

Anyone care to share an overview of a Transient Stability Study?
08-04-2014 02:19 AM
Top #2
Alan Maltz
08-04-2014 02:19 AM
Bill, I have to agree, on the face of it it's an odd request. I would ask more information, the requester may have some local generation and/or large motors that he's trying to start, maybe he's at the end of a long radial line with poor regulation. Maybe he's using the term incorrectly and means power quality, voltage dip/surge, etc. As we often say in these posts, more information is required.

08-04-2014 04:40 AM
Top #3
Bill Swingle, P.E.
08-04-2014 04:40 AM
Thanks for answering. The site is merely a utility fed build in San Jose. I suspect the engineer just selected the wrong spec. I'll figure it out. But it does point out my ignorance.
Care to to enlighten me on Transient Stability Studies? Unfortunately I've never seen one!
08-04-2014 07:00 AM
Top #4
Matthew Pilgrim
08-04-2014 07:00 AM
Hi Bill,

I agree with Alan, the client could be concerned about switching transients for large reactive loads, or stability of on-site power generation, particularly if it synchronises with the mains supply. Or, it could be a combination of both (i.e. the response of on-site generation to switching of large loads).

Best to have a conversation with the client to find out exactly what their concerns are, then get hold of the single-lines and any other information for the site and advise them which studies you believe are appropriate.

IEEE Std 399 (the Brown Book) is a good reference for the various types of studies.
08-04-2014 09:43 AM
Top #5
Bill Swingle, P.E.
08-04-2014 09:43 AM
Of course The Brown Book! What was I thinking? Or not obviously.

It's discussed in chapter 11. Thanks for the tip!
08-04-2014 12:15 PM
Top #6
Enrique Gallegos
08-04-2014 12:15 PM
Sometimes when induction motors constitute a main portion of the system load, stability analysis is performed not only when there are on-site generation.

"Stability analysis of Induction Motor Networks" by D.H Popovic, Electrical power and energy systems, Vol 20, No. 7, 1998.

Agree with other comments: Have a detailed conversation with your client.

08-04-2014 02:25 PM
Top #7
Sujit Lande
08-04-2014 02:25 PM
I am also agree with others comments on stability. If anybody has performed stability study on large no. Small genset/ captive power plants then share the report with group members.
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