How to choose the busbar after SFC? 1

[jyj982001]

SFC is widely used in pumped storage power plant,but how to choose the busbar which is located in the output of SFC?
Any special characteristic of the busbar?how about its working status in low frequency electrical system?Are there any standards for the isolated phase enclosed busbar used in such enviroment?

P.S. SFC is static frequency converter.
the busbar is used in the starting circuit.

 

[TurbineGen]

The SFC is simply to get the generator up to synchronous speed correct? After that you are closing in the breaker to the GSU transformer?

Have you calculated how much power is required to turn the machine? Are you starting the machine with the draft tube/tail race purged? How much time do you calculate the SFC will be running?

We need more information to help you with this.

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If it is broken, fix it. If it isn't broken, I'll soon fix that.

 

[jyj982001]

The SFC is to start the motor.
Due to the SFC which the busbar is connected to,there will be low frequency electrical system in the busbar when the SFC takes fuction to start the motor.
I wonder how to define the charcteristic of the busbar because of this low frequncy system.
Just characteristic of the busbar used as the feeder of the SFC,nothing to do with others.
Thanks!

 

[TurbineGen]

So this bus bar is going to be an insulator supported isophase bus? In my experience, the isophase bus ws comprised of a bus bar system supported by insulators every couple of feet. The are specified by how much current they must carry, and how much mechanical stress they can take (such as in the event of a fault). Lower frequencies are seldom a problem for an isophase bus system, but then again, the ones I have used have been permanently connected to the machine so they were sized for several hundred Mega Watts, not just the starting power.

Here's what you need to do assuming you are using an iso phase bus:

Figure out how much power and current the bus bars will be carrying.
Calculate the maximum fault current in the event there is a failure in the generator on start up.
Calculate the forces on the insulator network that hold the Bus bar in the fault condition.

Usually, the continuous current designates the size of the bus bar, and the fault current determines the size, strength and spacing of the insulators. If you are not using an Iso phase bus, it might be helpful to include a starting reactor since forces during a fault would be increased significantly.

I hope that helps. If you can provide a little more information, I can be of more assistance.


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If it is broken, fix it. If it isn't broken, I'll soon fix that.

 

[GEORGE2311]

I agree with TurbineGen. For your info, just in case you can change design, a GE 6FA 102MVa turbine generator SFC is connected to the sfc disconnector with 3 per phase 400mm2 cables (GE design). In any case the cost is less than a bus bar.

 

[ScottyUK]

Normally the mechanical requirements to survive a fault will dictate a far heavier bar than the electrical requirements suggest. An overall diff scheme will provide rapid fault clearance which reduces the withstand time, but the assymmetrical peak fault current at the generator bus is among the highest you will find anywhere on the system and this determines the bracing required.

GE's design for their auxiliary packages tends to be the bare minimum that they can get away with, not necessarily the best engineering solution for the client. Can't really blame them for that I guess - the clients should take care when writing the spec!


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