Generator Station transformer

[HamidEle]

We proposed to feed the station transformer from the tap-off the bus duct on the generator side(13.8kV side). However our client expressed their concern of the potential issue with this scheme. Their argument is, if there is a fault on the station transformer, it would trip the generator. They proposed to feed the station transformer from the grid directly. The grid and the on -site generator supply the power to the plant under normal conditions. Any thought of this topic?

Thanks a lot.

 

[7anoter4]

The Station Auxiliary Transformer [SAT] it is also a Black Start transformer and it is usually supplied directly from the Grid.
The Unit Auxiliary Transformer [UAT] will supply only the equipment connected with the Generator and no other.

 

[HamidEle]

The station transformer has three sources of supplies. One is from the grid, the second is from the gas turbine generator. The third is from Emergency generator. The concern is, the faults on the station transformer may trip the gas turbine. This may be avoided by protection schemes.

 

[7anoter4]

The auxiliary equipment in a Power Station as yard lighting and auxiliary pumps [of tank filling or sewing, for instance], office or workshop HVAC and other which is not involved directly in power generation has to be separated from turbine generator circuitry. The protection is a good thing but you cannot trust it any time. I think the Emergency Generator is for fire fighting pumps supply mainly. You can connect it with the Generator Auxiliary as a redundant power supply for Generator facilities.

 

[cranky108]

The emergency generator can also be for black start.

How do you feed the same transformer from three sources, or is it three different transformers?

You should have at least two auxilury sources, one from the generator bus, and the other from the grid. One is for start up, the other is so your auxiluries are not so sensitive to grid disturbances.

You can have another source for the offices and work shops from the grid, but that has nothing to do with power production.

Anyway, transformers don't fail that often. They are probally more reliable that the generator.

 

[HamidEle]

Cranky108,
The CO-GEN Substation SWGR is fed from three different transformers. One is fed the generator bus, the other is from the grid, the third is from the emergency generator.

Yes, I agree with you, aux. transformers don't fail very often and they are more reliable than the generators. To avoid the nuisance trips on the generators, we can set alarms instead of trips on generators from Aux. faults.

 

[cranky108]

Just a comment: But people get very excited about how equipment failures will affect them, but when you tell them the cost of backup equipment, they suddenly are not that concerned.

I guess money talks.