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Auxiliary Consumption and Limits

03/15/2021 7:30 AM

The topic of recent discussion in our Power system is the auxiliary consumption.
In our power stations meters are installed at generator terminals,at source of Auxiliary for power station and at exit points for power evacuation i.e transmission line.
Our Audit party says that the difference between reading of generator terminals and transmission lines(difference between generation and net electrical output) is our Auxiliary consumption.While our plea is that this difference includes losses in bus ducts,losses in excitation system,losses in power transformers which can not be counted towards Auxiliary consumption.
I want to know opinion of forum.
Also are there any standards set for these losses

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#1

Re: Auxiliary consumption and limits

03/15/2021 8:03 AM

<...plea is that this difference includes losses in bus ducts,losses in excitation system,losses in power transformers which can not be counted towards Auxiliary consumption...>

Well, what are they then? If they're not going through the meters, then they're not supplied to the <...transmission line...>.

Of what value is the <...opinion of forum...>?

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#2

Re: Auxiliary Consumption and Limits

03/15/2021 11:20 AM

Well we the public have to pay for efficiency losses as well...efficiency losses are part of any electrical system....

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#3

Re: Auxiliary Consumption and Limits

03/15/2021 11:41 PM

If it is not charged to Auxiliary Systems, then it would be charged to Unit Efficiency, which is another variable that changes with unit output, and is heavily dependent on the original design and design operating points. There is some value in tracking this operating variable, although all of the comparable units in the system should be evaluated the same way.

The only value we care about is cost per unit energy delivered to the transmission system (assuming operation within design life parameters). Breaking these costs down into categories is just for diagnostic purposes, so the more categories you have, within reason, the more effective your diagnostic activities will be. I would posit that your method would be superior for effective diagnosis of your operations, and simple enough to do.

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#4

Re: Auxiliary Consumption and Limits

03/16/2021 12:47 AM

I agree that it has to be charged but how can we charge it to auxiliary.for us there is a limit allowed in generation licence for Auxiliary consumption.When these losses are included that limit is crossed.

Another question.Is there any standard like IEEE which sets limit to such losses

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#5
In reply to #4

Re: Auxiliary Consumption and Limits

03/16/2021 1:55 AM

It seems strange that there would be a legal limit for auxiliary consumption, perhaps due to some shady operators using public money or resources to support operations not dedicated to power generation. The authority granting the license appears to be your only recourse, which may require a legal opinion on the intent and perhaps the basis of the auxiliaries limit. I would think that perhaps pollution control measures that weren’t considered in the original license calculation language could be the source of the discrepancy, and perhaps the limit needs to be adjusted, or perhaps removed as a clumsy method to ensure ethical business operation.

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#6

Re: Auxiliary Consumption and Limits

03/16/2021 1:58 AM

How can one set limits for Auxiliary loads in the power station. I have worked in a number of power stations and the Auxiliary load is the load supplied to generate the power as sold to the transmission company.

It is what it is, thinking of coal fired power station the auxiliary loads are the ID fans, FD fans, Boiler feed pumps, Condenser pumps, Hydrogen circulating system (assuming you are running H2 cooling) Precipitation or bag filter system, Conveying system, pulverising system, compressed air, RO water system, condenser cooling water pumps, ash handling and so on, every one of these systems is an auxiliary load and everyone is critical to the production of electricity. Remove one and the generator has to be wound back in output or islanded.

Every system has an efficiency factor an these create losses. The power generated minus the power sold is the auxiliary load of the station to generate the power.

This to me seems to be an introspective navel gazing effort by a bunch of bean counters trying to justify their self adulating positions.

As I said it is what it is and it takes what it takes to generate the power which seems to be about 10% of the generator output used in creating the power

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#7
In reply to #6

Re: Auxiliary Consumption and Limits

03/16/2021 3:51 AM

<...This..seems to be an introspective navel gazing effort by a bunch of bean counters trying to justify their self adulating positions...>

Quite.

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#8

Re: Auxiliary Consumption and Limits

03/17/2021 5:22 AM

Conditions defined in the contract will decide the items those are covered in the auxiliary equipment list. If it is a turnkey contract then each and every component that consumes power will be part of this list. In split contracts, like boiler, turbine generator, power transformers and auxiliary transformer etc., each contract defines the equipment to be accounted for auxiliary power consideration. I found in many contracts where the auxiliary power limit is specified or guaranteed by the equipment suppliers and penalty for each extra KW of auxiliary power is charged as penalty as per the conditions of the contract . This auxiliary power is measured under standard working conditions and demonstrated by the equipment suppliers.

In your case, your contact with the equipment suppliers would have given the figures of guaranteed auxiliary power and the equipment included for accounting the same. This may help you defend the audited results.

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#9

Re: Auxiliary Consumption and Limits

04/19/2021 2:29 PM

Late in the day, but an important point no-one mentioned.

Suppose the generator metering A and the delivered from station fiscal metering B have +/- 1% error at rated power and auxiliary power X is 5% of delivered power.

The A - B error is 2 %, as an estimate of auxiliary power. That is 2%/5% = 0.4 X error in the supposed auxiliary power. Error of +/- 1% in the metering on the auxiliary transformers High Voltage side is negligible in comparison.

As an engineer, I would never deceive myself into thinking the small difference between two meters was more accurate than actual measurement at the T-off point.

It seems to me to be accountants trying to shift costs from one part of organisation to another - rather than contributing to actual efficiency of generation with real costs.

67model

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