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Subject: RE: [emix] Plane of Control vv. Transactional Energy
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David: Thanks for the explaination. That
makes perfect sense in that context. I think you are saying that at some point
the business decisions and program decisions are made and passed on down the
hiearchy. The decision point you describe could be defined in a flexible
manner. But there is some point where the actions take place and the physical
load-impacting technology responds appropriately. For example does a
building control system make that decision for the entire building? Or is
the information passed along to a thermostat, as in your example, where that
final translation takes place. Or could it be a group of thermostats
negeotiating for their turn to operate their region? Depending on the
particular system, building, community, appliance etc, that decision could
occur at a different point. I think you were describing these potentially
overlapping points as “planes of control”? Thanks again, Gale Gale R.
Horst Electric
Power Research Institute (EPRI) From: Holmberg, David
[mailto:david.holmberg@nist.gov] 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: 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 301-975-6450 |
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