Ampacity of bus bar sections

[Mbrooke]

Is it possible, or ever practiced in the real world to push more MVA through a substation than its bus bar rating? Ie, if I have a 5000amp rated 345kv bus, is my substation rating limited to 3000MW, or can I push more power through it by alternating incoming and outgoing load elements such that any bus section is only carrying the resultant phase angle differences? Ie 6000MW+ power flo in/out. In such a case is bus bar protection necessary and if so how would I go about doing it?

 

[waross]

You should be using MVA rather than MW. 3000 MW at 50% PF = 6000 KVA.

Ie 6000MW+ power flo in/out. In such a case is bus bar protection necessary and if so how would I go about doing it?

At 6000 MW what is the MVA? What is the actual current in the bus?
At what temperature is the bus current rating stated?
Is it possible to re-rate the bus at a higher temperature?

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[bacon4life]

Yes, alternating sources and loads does allow larger amounts of power as long as no section is loaded to more than the amp rating. There was a thread a while back discussing the implications of this approach. The bus protection would be provided more by design and operation of the power system rather than by relaying. One of the reasons utilities are moving to more detailed transmission modeling is to be able to simulate and/or monitor flows through all sections of a bus bar.

 

[Mbrooke]

My bad- MVA- not MW- was thinking load pocket rather than power flows.

Station can not be re-rated, 5000amp is the final continuous number. Anything over that goes into LTE and STE action limits.

 

[7anoter4]

If the point A switchgear is 10 kA rated the bus could be 5 kA rated.

 

[Mbrooke]

@7anoter: Yup- close to what I was thinking.

 

[Mahmoud-Abdullah]

according to above photo, yes you can implement that configuration if the loads are halfed on the two sides of incoming but there is one issue. Will the connection from incoming to bus bar withstand the overall ampacity??

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