To continue this
excellent discussion.
First, for the benefit of
Francis below is a link to White Paper on Transactional Energy that, in part,
deals with ancillary services in a way that I think levels the field between
generation, storage and loads as providers of ancillary services. The idea is to facilitate energy transactions
on shorter intervals including 4-second intervals for frequency regulation.
Download Document:
http://www.oasis-open.org/committees/download.php/37464/Transactional%20Energy%20White%20Paper%20Draft%20007.pdf
With respect to David's quest for simplicity, I think we are
closer than it might seem.
David wrote (italics) :
So my real time scenario would run something
like this:
1) Power source queries grid for status of
existing available storage devices with surplus capacity
2) From responses and my available power - I
commit with a couple of them to push power to them
- to determine this I just need ROM
calculations that tell me they can absorb the power at the rate I'm generating
it.
- their availability should be immediate,
or time when to commence charging
- indicate status update refresh
period for 20% change in stored power or full - depending on anticipated
storage rate - this you can calculate - either from history of previous service
to that device - or device itself can give you estimate - if you are off by a %
it won't be a big deal.
3) Commence power distribution
4) Receive regular status updates from devices
of their new storage level and remaining capacity.
5) Compute decision - continue power supply or
loop back to 1)
6) If no storage devices available - then scale
back power generation - until receive storage notification from device
available.
My revision.
1) Power source queries storage providers or
brokers for quotes to store (buy) 25 MW per hour from 2 am to 5 am ( 100 MWh)
2) Generator accepts the
best quote of $25 per MWh.
3) Generator requests
quote to store another 100 MWh for the same hours.
4) Storage providers are
full and provide no further quotes.
5) Generator scales back
generation to store only 100 MWh.
Note your example talked
about where the power was stored and not what the generator got back ( money or
energy) and when. My example assumes the
generator gets money for the stored energy.
Perhaps a better transaction
with storage is as follows: Generator
requests a quote for storing 100 MWh from 2 am to 6 am and drawing 80 MWh from
2 pm to 6 pm, ( accounting for a rough 80% round trip storage efficiency).
The storage provider
might quote $50 per MWh stored for this service.
Ed
From: David RR Webber (XML) [mailto:david@drrw.info]
Sent: Tuesday, April 27, 2010 8:02 AM
To: Considine,Toby (Campus Services IT)
Cc: fcleve@xanthus-consulting.com; Phil Davis; Toby.Considine@gmail.com;
emix@lists.oasis-open.org
Subject: RE: FW: [emix] Power storage strategies
I'm still urging for
keeping this really simple!
From the perspective of
the supplier for the surplus power to push to the storage device - how much
precision do you really need!?!? Frankly I really don't need to know much
about the device beyond how much capacity to a ROM (Rough Order of Magnitude).
Why over engineer this - if you can use simple tracking messages to see
how you are progressing? Remember when a 5Mb hard drive was a big deal?!
Expect market to drive demand for low cost buckets of storage in
future...
So my real time scenario
would run something like this:
1) Power source queries
grid for status of existing available storage devices with surplus capacity
2) From responses and my
available power - I commit with a couple of them to push power to them
- to
determine this I just need ROM calculations that tell me they can absorb the
power at the rate I'm generating it.
- their
availability should be immediate, or time when to commence charging
- indicate
status update refresh period for 20% change in stored power or full - depending
on anticipated storage rate - this you can calculate - either from history of
previous service to that device - or device itself can give you estimate - if
you are off by a % it won't be a big deal.
3) Commence power
distribution
4) Receive regular
status updates from devices of their new storage level and remaining capacity.
5) Compute decision -
continue power supply or loop back to 1)
6) If no storage devices
available - then scale back power generation - until receive storage
notification from device available.
What I would anticipate
is that scenario 6) is really about always having enough storage capacity available
to balance demand.
From our XML perspective
- so long as our simple message designs contain enough information to drive the
decision making - we don't need more. E.g. we want minimalistic message
design. People will always think of more and more exotic information that
can be added - we want to strongly resist that - and require ONLY the
information needed to drive a working process - nothing more. Remember -
the messages do NOT need to contain information that can be obtained elsewhere.
Otherwise you end up with a standard that is extremely tough to implement
- and then even worse to have consistent interoperability across vendors.
Plus break the messaging down into small discreet purposes. For
example - I do NOT need to send device profile but once - first time device is
available.
-------- Original Message --------
Subject: RE: FW: [emix] Power storage strategies
From: "Considine, Toby (Campus Services IT)"
<Toby.Considine@unc.edu>
Date: Tue, April 27, 2010 9:44 am
To: Phil Davis <pddcoo@gmail.com>, "Toby.Considine@gmail.com"
<Toby.Considine@gmail.com>, "emix@lists.oasis-open.org"
<emix@lists.oasis-open.org>
Cc: "fcleve@xanthus-consulting.com"
<fcleve@xanthus-consulting.com>
Well, I think you are
correct.
The discussion of the
performance attributes or an offering that we skated around last month are
really about ancillary services….
Time to respond after
request?
Ramp time after
response?
Maximum sustained
response (define sustained)
These are all aspects
of being able to fit DR to ancillary markets, not just to “traditional” DR. As
most of them are some sort of “meet or exceed” expectations, the same DR could
be offered to different markets. Alternately, the building owner could easily
see how system augmentation to improve a performance metric would allow the
building to play in a more lucrative market…
"If flies are
allowed to vote, how meaningful would a poll on what to have for dinner be, and
what would be on the menu?" - Unknown
Chair, OASIS oBIX
Technical Committee
Co-Chair, OASIS Technical Advisory Board
Facilities Technology Office
University of North Carolina
Chapel Hill, NC
|
|
blog:
www.NewDaedalus.com
|
From: Phil Davis [mailto:pddcoo@gmail.com]
Sent: Monday, April 26, 2010 9:10 PM
To: Toby.Considine@gmail.com; emix@lists.oasis-open.org
Cc: fcleve@xanthus-consulting.com
Subject: RE: FW: [emix] Power storage strategies
Frances is right of
course. John Kueck at Oak Ridge feels there will come a time that the
demand side is the total resource for reliability and regulation. Though
I'm not sure of the 100% level, there are aspects of ancillary service participation
that properly implemented and managed would (I think) be more appealing to
commercial buildings than would traditional DR programs. I have
been assuming, perhaps wrongly, that our discussions energy communications
would include support of ancillary services. Is this correct?
From: Toby
Considine [mailto:tobyconsidine@gmail.com]
On Behalf Of Toby Considine
Sent: Monday, April 26, 2010 3:35 PM
To: emix@lists.oasis-open.org
Cc: fcleve@xanthus-consulting.com
Subject: FW: FW: [emix] Power storage strategies
I forwarded this
conversation to Frances Cleveland, who is working on electrical standards for
storage management (the complicated process we are trying to stay out of). Thee
followed back with a an interesting analogy of the more valuable types of
response dictated by ramp time, response time, et al.
"If something is
not worth doing, it`s not worth doing well" - Peter Drucker
OASIS Technical
Advisory Board
TC Chair: oBIX & WS-Calendar
TC
Editor: EMIX, EnergyInterop
|
|
|
From: Frances Cleveland [mailto:fcleve@xanthus-consulting.com]
Sent: Monday, April 26, 2010 3:06 PM
To: Toby.Considine@gmail.com
Cc: emix@lists.oasis-open.org
Subject: Re: FW: [emix] Power storage strategies
Toby -
Just to add to the mix, I did not see "ancillary services" in this
discussion - these are services like var management, frequency deviation
mitigation, load following, etc. These are huge issues for utilities, and just
like derivatives are often more "valuable" than stocks in the stock
market, are often of more value to the utility than just energy.
If I can't send this directly to the emix list, please forward .....
Frances
At 11:52 AM 4/26/2010, Toby Considine wrote:
Sharing the conversation
that broke out today in EMIX…
"If something is
not worth doing, it`s not worth doing well" - Peter Drucker
Toby Considine
TC9, Inc
OASIS Technical Advisory Board
TC Chair: oBIX & WS-Calendar
TC Editor: EMIX, EnergyInterop
Email: Toby.Considine@gmail.com
Phone: (919)619-2104
http://www.tcnine.com/
blog: www.NewDaedalus.com
From: Ed Cazalet [mailto:ed@cazalet.com]
Sent: Monday, April 26, 2010 2:50 PM
To: 'Phil Davis'; 'David RR Webber (XML)'; Toby.Considine@gmail.com
Cc: emix@lists.oasis-open.org
Subject: RE: [emix] Power storage strategies
David,
Thanks for getting an informative debate going.
I assume that you are suggesting that storage can be generically modeled as a
device with a MWH capacity, a power ratio for both charge and discharge of say
4 MW per MWH (4 to 1 ratio) and a current state of charge (% of the MWH energy
capacity) with some updating of these parameters as necessary.
Further, I assume you are suggesting that this information be used by
other parties ( and possibly the owners ) to dispatch the storage.
However you have not mentioned how third parties would be charged or contract
for the use of the storage.
Keeping with your idea to keep the storage model simple. we would need at least
also specify a round trip efficiency of storage devices since this efficiency (
MWH Out / MWH in) can vary between 50% and over 90% for various storage
technologies. Additionally, some compressed air energy storage devices
(CAES) also require natural gas as an input energy source in addition to
electric energy. ( Note: round trip efficiency is also a function of state of
charge and rate of charge and discharge, but let's say we ignore that for
simplicity.)
A fixed power ratio is also problematic for many storage devices. Many
batteries have asymmetric charge and discharge ratios, so that we would need to
specify different ratios for charging and discharging. Additionally, many
batteries are able to charge or discharge at high rates for short time periods
or when they are not near full or not near empty and then at much lower rates
on a sustained basis.
Another critical parameter is response ramp rate. Some devices such as
batteries and flywheels have an almost instant response whereas pumped hydro
and CAES have a much slower response, limiting their value for frequency
regulation.
Battery life is also an issue. A battery typically might be able to
discharge a fixed number of MWH over its life depending somewhat on how
charging and discharging is done. So charging and discharge for small
economic benefit must be avoided to save the battery for situations where such
use has high value.
What information we provide about storage also depends on what side of the
plane of control (energy services interface) we might be on. On the
storage device side of the interface, the physical models that you suggest may
be useful, however the need to over simplify is less.
On the inter domain side of the interface communicating even a simplified
storage model to other parties and then figuring out how to dispatch that
storage in coordination with generation and load is challenging. US ISOs
are currently working on tariffs and software to allow limited energy devices
such as flywheels and batteries with 15 to 30 min of storage to participate in
frequency regulation markets. It is a significant software and market
design challenge to recognize the limitations of storage (which vary by device
type) in comparison to generation while at the same time given storage the
benefit to the system of the much faster response of storage in providing
regulation services. And most have not yet fully implemented the economic
dispatch of deeper storage devices into their economic dispatch and locational
pricing models.
If avoiding over complication by engineers and striving for simplicity is a
goal, then I recommend the pure simplicity of Transactional Energy outside of
the plane of control of specific devices. What is done inside the plane
of control is another matter, where the specifics of each device are much
easier to accommodate.
With Transactional Energy a storage owner can make or accept an offer to buy
MWH at a given rate and at given low price at night or when the wind is blowing
hard. The amount and price will depend on many factors such those we have
discussed above. The storage owner can also make or accept an offer to
sell energy at a higher price in the afternoon or when the wind is not
blowing. A party could perhaps simultaneously enter into a transaction to
sell in the morning and buy in the afternoon from the storage owner. This
is real simplicity and it is the way we buy and sell almost everything else in
our life..
Perhaps as both an economist and an engineer, I can revise your statement
" Never under estimate an engineer's ability to add complexity!
to say, "Never underestimate the ability of an economist's market to make
simple what an engineer can make complex!"
Ed
Edward G. Cazalet, Ph.D.
101 First Street, Suite 552
Los Altos, CA 94022
650-949-5274
cell: 408-621-2772
ed@cazalet.com
www.cazalet.com
From: Phil Davis [mailto:pddcoo@gmail.com]
Sent: Monday, April 26, 2010 8:27 AM
To: 'David RR Webber (XML)'; Toby.Considine@gmail.com
Cc: emix@lists.oasis-open.org
Subject: RE: [emix] Power storage strategies
Actually, GE announced such a system last week and is hiring 400 people in
Atlanta to staff the new business. It's a substation level product. Also,
I have spoken personally with people at Hitachi and Samsung who are testing a 1
MW battery. Such a battery from another vendor is in test operation
behind PJM's main offices. So local here takes on a new meaning depending on
whether it is truly behind the customer meter, or behind the distribution grid
meters (substations and the like), or on a transmission system.
Theoretically, batteries of this size could replace generators used for voltage
or frequency support.
Phil Davis
From: David RR Webber (XML) [mailto:david@drrw.info]
Sent: Monday, April 26, 2010 10:58 AM
To: Toby.Considine@gmail.com
Cc: emix@lists.oasis-open.org
Subject: [emix] Power storage strategies
Toby,
It occurs to me that local storage can potentially play a role here - depending
on its efficiency of course. One can anticipate that future technology
will offer higher % there - especially if market forces drive that equation.
Therefore - a future system could offset power surges by drawing on locally
stored resources that were captured during off-peak or excess capacity.
In fact such a system may notify suppliers that they can "push"
excess power to local storage at some pre-determined cost point - and of course
also need to indicate that the storage facility is at a certain % level, or if
empty - accept units at a higher cost rate.
DW
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