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Subject: RE: [emix] EMIX Approach
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Below is my pass on Toby's latest pass to simplify the EMIX Approach
in Section 3.1 related to EMIX
Product Definitions and WS-Calendar.
Comments? An energy product typically has elements that vary over
time. Five kW at 2:00 AM does not
provide the same energy services as five kW at 2:00 PM. EMIX describes
products for which time is an essential characteristic. For example, the price
and quantity (rate of delivery) of energy in each time interval of a sequence
of intervals may vary for energy transactions made in a sequence of intervals. An EMIX Product Description describes the elements of an energy
product for one time interval or a sequence of time intervals. An EMIX Product Description for a constant rate of delivery power
product over a single interval of time comprises a(1) start time, (2) duration,
(3) rate of delivery, and (4) price. If the rate of delivery(kW) and price ($/kWh)
have been messaged in advance, the message to deliver the product is simply
“start (reference Uri to product) at 3:00 AM for 0.75 hours.” A Product Description over a sequence of interval could describe
elements again and again for each interval. Only a few elements, perhaps only
price, or quantity, may change per interval. EMIX specifies product elements
once, and then specifies which elements may vary by the time intervals of a
sequence. For example, a responsive load may require 15 minutes lead
time before a load reduction. This characteristics may hold true whether a
response is requested for a run-time of 10 minutes or 10 hours. EMIX specifies
these invariant characteristics as part of a product, while offering the
variable run-time to the market. EMIX defines an EMIX Sequence as a sequence of EMIX Intervals.
An EMIX Sequence has a single start
time and a duration for each EMIX Interval. Each EMIX Interval carries those product elements,
such as price, that vary by the interval.
EMIX uses WS-Calendar as a standard for describing an EMIX Sequence and
an EMIX Interval.
For example, a Product Description may have sequence of 10
consecutive 15 minute intervals, each with a different quantity (or different
price). Rather than describing a start time, a quantity, and a price, 10 times,
EMIX uses an EMIX Gluon associated with the sequence, letting you put the product
description, start time, and price in the EMIX Gluon, and have only the
quantity in each EMIX Interval. EMIX Product Descriptions using EMIX Intervals and EMIX Gluons
provide a very flexible information model for describing any energy product.
This means that new or specialized energy products can be defined without
changing the EMIX standard. EMIX Product Descriptions also minimize the size of product
descriptions and messages by efficiently
describing how elements of a Product Description may or may not vary by time.
This reduces communication overhead. EMIX Product Descriptions use WS-Calendar which embodies the
same calendaring standards used by most business and personal calendaring systems. This enables greater interoperability between grid systems and business and
personal systems. Edward G. Cazalet, Ph.D. 101 First Street, Suite 552 Los Altos, CA 94022 650-949-5274 cell: 408-621-2772 From: Toby Considine [mailto:tobyconsidine@gmail.com] On
Behalf Of Toby Considine At the walk-though, it was suggested that the entire section
3.1 was confusing and seemed to over emphasize WS-Calendar Here is another pass… Energy is a product that varies over time. Five KW at 2:00
AM is not the same product as Five KW at 2:00 PM. EMIX describes products for
which time, the interval in which it is delivered, is an essential attribute.
For energy purchases made in consecutive intervals, prices and quantities may
vary for each interval. EMIX describes products for which a key characteristic
is variance over time, whether the product is generation or load reduction, wind
or coal, power or regulation. For the simplest product, the dispatch of power, EMIX is
simply a product description (constant power), a start date and time, a
duration, a quantity, and a price. If the rate and price have been set in
advance, the dispatching communication might be simple “start at 3:00
(reference uri to product), for 45 minutes.” It is often desirable to discuss a sequence of intervals in
which to purchase electric energy. In any set of intervals, most information
would be redundant. The same product could be described again and again, once
for each interval. Only a few characteristics, perhaps only price, or quantity,
might change per interval. EMIX specifies product information once, and then
specifies only the changes in each interval. Some energy products have characteristics that present a
consistent pattern over time, whenever purchased. A generator may run at half
speed for an hour while warming up. A responsive load may require 15 minutes
before load reduction. These characteristics may hold true whether generation
or response is requested for 15 minutes of 15 hours. EMIX specifies these
invariant characteristics as part of a product, while offering the variable
run-time to the market. The EMIX Product Description specifies the characteristics
of a product at a given instant in time. The EMIX Products uses WS-Calendar to
express how that product varies over time. WS-Calendar describes how a single
specification can be shared between a sequence of time intervals, and a gluon,
which describes aspects of the specification shared by all, including, perhaps,
the schedule for the sequence. WS-Calendar also another gluon can associate
with the another gluon to influence a gluon-sequence information set. A sequence could also have 10 consecutive 15 minute
intervals, each with a different quantity (or different price). Rather than
expressing a product description, a start date and time, a quantity, and a
price, 10 times, EMIX uses a gluon associated with the sequence, letting you
put the product description, start date and time, and price in the gluon, and
have only the quantity in each interval. If a market rule stated that there was no price for a ramp
period, the first interval could have a price of zero. In that case, that first
interval could have a price of zero (blocking the price coming from the gluon).
All other intervals could get the price from above. The same override capabilities go to any variable. If the
ramp periods have a fixed time, but the run time is variable (describing a
typical generation resource, and perhaps most DR assets) then the duration can
be expressed in the gluon, inherited by all intervals that themselves do not
have a duration, i.e., the generation load, and ignored by those that do, i.e.,
the ramp times. But the simplest (one price, one time, one interval, one
duration, one amount) explicit invocation, and the simplest implicit (do that
thing, one time) invocation are still invoking the EMIX Product, consisting of
a Gluon holding a Product Definition, Start Time, and a sequence. “It is difficult to get a man to understand something,
when his salary depends upon his not understanding it” -- Upton Sinclair.
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