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Subject: RE: [emix] Plane of Control vv. Transactional Energy
Hi Gale, My quoted statement below was in
reference to within the customer domain there is some plane of control below
which there is no control. At that point there must be programming that
translates price to control. Some human must set some boundaries on how that
control maps to a price. Does that make sense? If in a market bid arrangement,
say with individual offices competing for cool air, then I might program an
agent at each thermostat to bid a higher price with some relationship to the
number of degrees above normal. Thanks, From: Horst, Gale
[mailto:ghorst@epri.com] David: The plane of control description you mentioned is an
interesting element to consider. The description, along with the
“other priorities” mentioned, seem to indicate there are multiple
intersecting planes of control and locations for the human interface. We
need to have some elegant simplicity to have a managable system that still
leaves the desired planes intact. There was one statement that seems a bit delicate.
“If some loads must shut down, then we must have rules that say
‘you go to this mode at this price, and shut down at that price’
for all such loads/systems/devices. “ This seems to be trying
to force a price system to behave like direct load control program. In my
opinion, we need to be very cautious of this idea of using price for a forced /
absolute response. In the human dynamics process of making significant changes,
there is a tendency to want to make the new system function like the old system
to which we have grown accustomed. Sometimes this indicates that we have
not adapted to the change and the benefits or features it entails. In
this case there may be reason to also have DR/DLC signals or emergency signals
separate from price. However, we may want to hesitate on the expectation
of having price system with a point where a system “must” shut
down. It may be more realistic to assume that, over time, we will
develop are reasonable amount of statistical reliability based on experience
with pricing. Gale Gale R. Horst Electric Power Research
Institute (EPRI) From: Holmberg, David
[mailto:david.holmberg@nist.gov] So, I wanted to think more about this “plane of
control” concept as it relates to Ed’s doc on TeMIX http://www.oasis-open.org/apps/org/workgroup/energyinterop/download.php/37301/Transactional%20Energy%20White%20Paper%20Draft%20004.pdf A refrigerator can be smart enough to monitor a price and
see that the price is higher or much higher than normal and take energy saving
measures. It can learn a daily routine and plan accordingly. It really
doesn’t need any higher level control, because no human is going to
bother to tell it “I have a load of groceries coming this evening with
some potentially warm milk, so please pre-cool before 6pm.” A home thermostat can have a pre-programmed schedule that is
used to adjust temperature. That is the control plane for the different
components of the heat pump/furnace/AC. But the thermostat may pay attention to
other inputs, like a door sensor that indicates an occupant’s arrival and
need to lower the temp, or certainly an occupants direct override. The
thermostat watches the price and the house temp profile may be adjusted
accordingly. There may also be DR signals that effectively move the plane of
control outside the home (even though the homeowner has essentially contracted
some grid-side service partner to handle energy management). A commercial HVAC controller takes this to a higher level,
with more sensor and human inputs, and variability in schedules. A building may
define common operation modes for different zones. A schedule for facility use
determines which modes apply at a given time. The price of electricity will be
cross-cutting input, adjusting each of the operation modes, perhaps bumping
operation from one mode to another, or into additional cost-saving modes. Microgrids somehow imply local power management: maintaining
voltage, managing load/storage/generation, and ability to go
“off-grid”. Some microgrid controller may micro-manage these things
or instead use a market mechanism to manage. We can have algorithms on the
storage that indicate when to store or deliver based on price. The real test is
when we lose the big-grid supply and can we manage voltage and phase.
It’s not clear to me that price messaging/markets can do that. Besides
the electrical challenges, to make the load/gen/storage balance work, we will
need significant pre-programmed rules for load flexibility. If some loads must
shut down, then we must have rules that say “you go to this mode at this
price, and shut down at that price” for all such loads/systems/devices.
Is the question of “plane of control” the same
as “where is the human interface?”, unless (as in the case of the
refrigerator) there is no human interface? And in the case of a campus or
microgrid there are effectively multiple human inputs that impact a single
system. There is the building operator and the human resources office and the
Energy management director’s office and the “how green we want to
be” CEO office. Each of these impacts decisions about conditions on
energy use, and how and when and why. Hopefully they all work together to have
a consistent policy for response to price signals and other priorities. It’s the “other priorities” that Toby
brought up on the call. Price is not all that matters. Maybe source matters.
Maybe local matters—that might be factored in as a price adder on
external power. Other priorities might be reflected as exceptions in the policy
for a particular system, like “the bowling alley will never go into reduced-power
mode when the director has bowling league”. Perhaps some of this ought to be discussed in the TeMIX
paper. David Holmberg NIST Building and Fire Research Lab 301-975-6450 |
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