I am working in a 110MW thermal power plant.
here we maintain 11KV or less generator terminal. So, i want to know where will be beneficial regarding to auxiliary consumption.

 

You cannot change the nominal voltage of a generator. it has been design for 11kv it should stay at 11kv and all the auxiliary should also be designed for this 11kv (most probably through stepped down transformers)

 

Pascal... I disagree with your position that voltage should be held at the nominal or rated value.

There is benefit to raising the voltage, from 5 to 10%, in most (but not all) cases. The principal gains are a reduction of in-plant wiring losses, and an increase in the efficiency of operating motors and transformers (to a lesser degree)!

I have presented a number of studies to clients that illustrate the point. If you (or anyone else) would like a copy of those studies, please contact me.

Regards, Phil Corso (cepsicon [at] aol [dot] com)

 

> I have presented a number of studies to clients that illustrate the point. If you (or anyone else) would like a copy of those studies, please contact me. <

Regards, Phil Corso (cepsicon [at] aol [dot] com)

Any technical doc is always welcome. maybe you can share with anyone interested or if you please can you send it to passerat1 [at] netcourrier.com

 

Yes you are right nominal voltage can eventually be change within a few percent (to reduce current in order to keep same power). but what about MTBF of auxiliary equipment, in that case do you also have as study about the fact that equipment will be slightly (I do admit) over voltage (even if you keep it within manufacturer admitted range of the nominal voltage). better efficiency of equipment is the good point of it but if it does increase the maintenance rate or even worst the failure rate do it worth to be out of the nominal range? maybe? maybe not?

 

Most synchronous generators and AVRs (exciter regulators; excitation systems) are rated for a specific voltage, plus-or-minus 5%.

Perhaps Mr. Corso could tell us what kind of efficiency improvement could be achieved by running an alternator at approximately 5% higher than rated? Is it a fractional improvement (less than 1% of rated), or something higher? If it is significant, why don't most plants operate at a generator terminal voltage greater than rated?

Can the "load" accommodate the change in power factor? Do the transformers, main and auxiliary, have on-line tap changers which could be used to balance power factor?

There are a lot of mitigating factors in this scenario and, as with most operating decisions, it's a matter of analysis for each specific site and application and a judgement call on the part of management about operating in this mode for this kind of "savings".

Just as pascal says.

But, it would be nice if Mr. Corso would provide a synopsis of his paper, at least with respect to the efficiency improvement.

 

Mea Culpa... The comments I made about voltage increase were for utilization facilities!

Regards, Phil Corso