| The problem is that the customer returns this energy within the period (1/60
| second) that it he used itIt is not an "energy charge"- loaned or
| otherwise. What interest would be charged on a loan for 1/2 of a cycle? It
| is being charged through the energy metering. In addition, as I have said
| earlier this evening- KVARH metering does not reflect the actual losses seen
| by the utility.
| In the case above it is not an energy related issue but a voltage control
| issue which so far is quite a specific situation.
It is hard to tell from your writing whether your are saying that it is,
or is not, an energy charge. kVAR is certainly not energy used. But a
fraction of it is energy wasted, such as in voltage drop over the lines.
In these days of separate energy providers, accounting for that energy
waste is now important because a different company has to generate it.
-----------
The demand charges that I have seen are not energy charges but simply a
measure of the highest 15 minute or 30 minute) peak in the billing period.
As I said, it doesn't account for system losses. Nor is kVAR a measure of
energy wasted. If the pf is poor, the kVA/kW ratio will be higher and the
losses higher but kVARH or kVAH does not provide a measure of this.
However, a very good point that you have is that de-regulation (in addition
to wipig out proper load forecasting and optimisation of the generation mix)
does present problems in accounting for where the losses occur and whose
responsibility they are.
-----------
| My initial comment was "Does the size and cost of a utility transformer and
| lines feeding a specific plant depend on the time of day? If it were so,
| then your suggestion would be great." However, I think that you are going
| beyond this - doing "time of day" to bias the demand rate as is now done in
| many cases for energy rates. Interesting but considering that the demand
| charges are mainly related to the cost of equipment to supply a particular
| load ( further back in the system the effect becomes more diffuse so the
| costs of the immediate feed to the customer is the only one that can fairly
| be attributed to that particular customer- the more diffuse costs are built
| into the energy rate) and the equipment isn't going to change on a 15 minute
| cycle- there is a problem. What sort of "demand" metering most accurately
| represents costs?
Of course further back is more diffuse. With one supplier and distributor
as the same company, it wasn't much to worry about. Today it is more so.
And there is some fraction where the distrbution costs are increased due to
industrial users who make extra demands on the system and don't get metered
for it (if that is the case, which I think it is in many cases).
-------------
If all industrial users do have demand charges then that is one way to get a
handle on the problem-it doesn't cure all but the cure-all depends on a hell
of a lot of information to be transferred and interpreted. There will be
situations where more complex specific metering is needed to provide a fair
assessment.
| You are absolutely right in suggesting that such testing be done at night or
| off-peak times- The KVA demand is reduced and if time of day metering of
| energy is in place, the energy cost would also be reduced.
| Note that many large industries negotiate energy contracts which have a kVA
| limit- if the peak kVA is below a certain value then a "good" energy rate is
| available:-BUT if the kva demand exceeds this limit- the energy charge
| increases drastically. Many industries with their own generation, use such
| generation to shave the peaks and keep the charges from the utility down. If
| one has such capability it works well to the advantqage of both the utility
| and the customer. Many moe utilities use some form of pf correction-
| reduction of kVA demand as well as improved voltages.
And of course there should be a drastic increase, since the utility has to
invest in a specific level of capacity to provide the service. If you now
expect them to just supply you with more energy or more VARs or whatever,
they have to gear up for it.
| The idea is great but the problem is that back in the system- your load is
| absorbed into a melting pot. What demand that is measured at a customer
| level can be isolated as chargeable to that customer. How much effect that
| it has further up the chain depends on the size of that customer with
| respect to the sum total of all customers. Load diversity rears its head as
| well. Demand charges are meant to address costs associated with supply to a
| specific customer rather than overall system costs. .
| Can this be extended to consider overall system costs - in theory - Yes.
| However, in practice, when the cost of getting the data exceeds the saving
| gained from use of the data- don't bother.
Things like load diversity can actually be figured out with all that data.
Overall system costs need to be considered, and those costs apportioned to
customers properly based on their usage, demand, waste, etc. But yes, if
the cost of getting and working with the data exceeds the cost, then don't
do it. But those costs _are_ getting lower while the costs of maintaining
an electric grid go up (especially with the reliability and security issues
now days being raised). Electric utilities will be expected to invest in
more capacity, more reliability, etc. Those who are served more by that
are the ones that should pay more for it.
-----
True. I think we agree. However, one could measure each and every load kW,
kVAR,kVA, and all of these with H attached as well, but still not have a
proper assessment of system losses - where, when and how much, that is
sufficient for proper charging of losses to the customers.
I would respectfully submit that KISS (keep it simple, stupid) still has a
place. Utility x has %y of the total load and gets %y of the cost of
losses - I bet the utility would then look at its customers and bill
accordingly.
However, I am from the era where each utility had its own area and customer
base. They could buy bulk from other suppliers and did but were able to plan
their generation and transmission needs on a long term basis. Nowadays the
planning horizon has shrunk, and optimisation of generation, along with
economic dispatch and emphasis on reliability has been compromised.
--
--
Don Kelly
[email protected]
remove the urine to answer
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| Phil Howard KA9WGN |
http://linuxhomepage.com/ http://ham.org/ |
| (first name) at ipal.net |
http://phil.ipal.org/
http://ka9wgn.ham.org/ |
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