Time of Use Metering at Higher Voltages

[maxPE]

It has been suggest in this forum that I use 4800 or 4160 voltage for a 1.5 mile service extension. I'm am planning on installing a wind turbine (induction motor/generator) at the site to reduce my energy costs. California will allow zero net type of generation buy back. My question: is the higher voltage metering (4800) incompatable with TOU meters? Do TOU meters have the capability of recording the generated power by the wind turbine and subtracting that from the usage. This could be rather complex depending on the tariff TOU structure and the 'buy back' rules. I hate being a trail blazer!

Max

 

[busbar]

Bidirectional TOU metering in most of California is duck soup and is even used on residential photovoltaic E-NET applications.

 

[busbar]

Oops—didn’t address your question directly. Metering at the service voltage for any level is very common and done with instrument transformers—they scale everything down to nominally 120 volts and 5 amperes.

 

[dpc]

It could be expensive soup, though. In most cases, if the utility has to do anything related to you generating power, you must pay all of the costs associated with their work.

Maybe there are some exemptions for residential service, but for industrial customers, the utility charges for their modifications related to customer generation can be a real shocker.

 

[busbar]

Nowadays, “4-quardant” energy and power measurement is routine for microprocessor-based watthour meters, so they can register real and reactive quantities simultaneously [in either direction.] With induction generators, exporting kilowatts while importing kilovars can be metered with high accuracy, at multiple rate schedules changing hourly, daily and seasonally.

 

[mazhar123]

Dear friend

The following meter can solve your problem.

1] TOU meter from GE[USA] type 10A vector meter.

2] TOD meter Schlumberger [France] type A21E.

They all have [ Export + Import ] and [Export - import] facilities.

I mean can be programmed according to your requirements.


Mazhar ali[ Islamabad]

 

[ulibra]

Hi,

I deal with TOU meters dialy. We have a customer that has their own windturbine where they are metered with a TOU meter and TOU rates. Using a electronic meter and having it meter both directions of power for each TOU rate. In the
billing department they take these readings and calculate the total power consumed or produced. For example (assume one rate), if the meter read 115 KW del(or KVA, doesn;t matter same priniciples), and 156 KW rec that means you used 115 KW of the power corp energy and you gave 156 KW back to the power corp. The power corp would owe you $$ for 41 KW. This is a simple way of doing it. At high voltages the meter would be a secondary metering application where insturment transformers are used to step down the voltage and current to a meter level, usually 120 volts and 5 amps. If you wanted to figure out what you are actually using by reading the meter, take the register reading for each rate and multiply it by the ratio of the current and potential transformers and the meter multiplier (usually 1), this would give you the primary power usage, do this for each TOU register and for both del and rec.
Electrical Engineer
Nova Scotia, Canada

 

[SidiropoulosM]

Not directly related to your question but still relevant: the power company may require you to supply unity power factor at the generator terminals. This will add to your cost because you'll have to install capacitors or even a dynamic var source. (Induction generators are heavy consumers of reactive power, "var suckers" as we call them). Michael Sidiropoulos

 

[maxPE]

Thank you all for you helpfull advice. I recently ran into a fellow alt energy produce that verified the TOU metering with buy back. I was astounded that the utility give them a price factor of 3 on power produced in summer peak periods! Great. I am concerned about the reactive power produced by the wind turbine. From my limited college power class I seem to remember that reactive had to do with leading current or maybe just the opposite. I seem to remember in the tariff schedule that I would get charged if I produced vars of a certian magnitude or quanity. I hope that capacitors can do the corrections since a 'dynamic var source' sounds expensieve! Its just a little 30kw unit! Well, maybe two of them.....

 

[SidiropoulosM]

maxPE, wind turbines do not produce but consume reactive power, which must be supplied by the power company. The power company may require that you provide unity power factor, or something like 98% power factor. This means that you need to install a capacitor to supply the reactive power. The problem is that the wind turbine output fluctuates widely and so does its reactive consumption. The capacitor, therefore, will not be effective unless it's switchable in stages. Now that you mention that your output is only 30 kw, it seems unlikely there will be much of an effect and you should be fine. Michael Sidiropoulos