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Subject: RE: [emix] Plane of Control vv. Transactional Energy
David, Excellent, I will fold these concepts into the next
draft of the white paper. Thanks, Ed Edward G. Cazalet, Ph.D. 101 First Street, Suite 552 Los Altos, CA 94022 650-949-5274 cell: 408-621-2772 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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