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:
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
Edward G. Cazalet, Ph.D.
101 First Street, Suite 552
Los Altos, CA 94022
650-949-5274
cell: 408-621-2772
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 |
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 | | |
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
________________________________________________________________________
This email has been scanned for SPAM content and Viruses by the MessageLabs Email Security System.
________________________________________________________________________
--------------------------------------------------------------------- To unsubscribe from this mail list, you must leave the OASIS TC that generates this mail. Follow this link to all your TCs in OASIS at: https://www.oasis-open.org/apps/org/workgroup/portal/my_workgroups.php
******************************************
* Frances M. Cleveland
* Xanthus Consulting International
* 369 Fairview Ave
* Boulder Creek, CA 95006
* Tel: (831) 338-3175
* Cell: (831) 229-1043
* fcleve@xanthus-consulting.com
* www.xanthus-consulting.com
******************************************
________________________________________________________________________
This email has been scanned for SPAM content and Viruses by the MessageLabs Email Security System.
________________________________________________________________________