RE: [ws-dd] Discovery in Smart Grid applications

Thanks Antoine. That was very useful.

There is no direct access / VPN / … All access to anything inside the Resource is mediated by the application that has an ESI. That application can be as thin as operating a direct hard-wired closure, or as fat as an enterprise application encompassing many business policies.

Energy Interoperation is architected to be symmetrical and recursive. The microgrid behind the ESI (every end node is treated like a microgrid) may sometimes sell energy instead of buying. A microgrid may contain other microgrids. A microgrid may choose to manage its internal energy markets using Energy Interoperation, perhaps with different market rules than outside. An ESI could front an office park or a residential neighborhood, as well as a home, commercial building, or industrial site. An Energy Services Aggregator (ENERNOC, Constellation) or retail chain store may be constructed as a virtual microgrid, a single resource facing the market, and optionally exposing commercial buildings as an “Asset”.

The vast bulk of ESI’s, though, will face commercial buildings and homes. For now, there is no natural discovery inside the Resource. Someone will have to enter Assets into the application. Your water heater does not know how to be discovered. That could change.

It is not hard to imagine that significant home appliances and the smart thermostat could reveal and self-describe themselves. HVAC and major equipment in the commercial building could do the same. The application then would present the [owner] with the opportunity to expose some of these Assets to the energy market, and could negotiate favorable electricity rates for doing so. This could be the basis for self-assembling Energy Management networks within the premises.

ASHRAE SPC 201 (http://spc201.ashraepcs.org/) is developing an information model to be used by premise-based equipment. These could be the basis for the Profiles.

But as I see it, we will move from mandatory Asset participation of dumb devices (This tariff is allowed only with the right to turn off your hot water heater.) to market negotiation on their participation. Either way requires communications about “What assets are you offering for interaction”. If this feels like local discovery and secure remote publishing, well, so much the better.

Thanks again

"It is the theory that decides what can be observed." - Albert Einstein

Toby Considine

Chair, OASIS oBIX Technical Committee
U.S. National Inst. of Standards and Tech. Smart Grid Architecture Committee

Facilities Technology Office
University of North Carolina
Chapel Hill, NC

Email: Toby.Considine@ unc.edu
Phone: (919)962-9073

http://www.oasis-open.org

blog: www.NewDaedalus.com

From: Antoine Mensch [mailto:antoine.mensch@odonata.fr]
Sent: Thursday, February 10, 2011 5:45 AM
To: Considine, Toby (Campus Services IT)
Cc: Toby Nixon (Toby.Nixon@microsoft.com); francois2.jammes@schneider-electric.com; ws-dd@lists.oasis-open.org
Subject: Re: [ws-dd] Discovery in Smart Grid applications

Hello Toby,

let me have a try at answering your questions.

From your description, I assume the networked objects will look like this (hoping that the formatting is preserved):

                         Asset1
                           |
Smart Grid --- Resource ---|--- Asset2
                           |
                         Asset3

<--- Internet ---><------ LAN ------->

where the "Resource" is a kind of gateway that will implement the ESI.

In such architectures, there are several ways in which WS-DD and DPWS may be used:

- The Resource may expose the managed discovery interface defined by WS-DD: this will allow the Smart Grid clients to obtain a list of Asset public addresses, based on some query criteria. WS-DD defines Types and Scopes as standard criteria, but it is extensible. The Resource will still have to take care of the address translation between the exposed public address and the internal address of each Asset (unless you use a VPN or similar technology). Discovery messages are kept small by design, so the usual way of working once a client has obtained a public address for an object is to send a metadata request to the address to obtain more detailed information.

- The Resource may be able to automatically and dynamically gather information about available internal Assets by using WS-DD and DPWS: if each asset implements the Device Profile, then standard mechanisms (including ad-hoc or managed discovery and metadata exchanges) may be used by the Resource to discover Assets and their capabilities, and auomatically build its Asset database.

- Standard metadata exposed by devices compliant with the Device Profile include the list of available services and their WSDL description. If you need to extend this with your own metadata, you have two choices: (i) add a dedicated metadata service to each Asset; (ii) extend the standard metadata exchange mechanisms with your own dialect, using the standard extensibility mechanisms.

- If the Smart Grid clients are WS-Eventing compliant, they will be able to subscribe to events exposed by DPWS-compliant Assets and be asynchronously notified of important changes in the Asset state. Due to the presence of the Resource acting as a gateway, some kind of event brokering mechanisms may need to be added to route events from Assets to clients through the Resource.

Thus, my understanding is that you may use WS-DD and DPWS on both sides of your Resource:
- Externally, to allow clients to discover and access Assets through the Resource.
- Internally, to allow Resources (or energy managers) to discover Assets on the LAN.

From my personal point of view, I think the work you are describing is a great opportunity to highlight the benefits of WS-DD and DPWS in important real-life use cases.

Best regards

Antoine Mensch

Le 09/02/2011 21:45, Considine, Toby (Campus Services IT) a écrit :

Toby, Francois ( or any member of the committee)

I’m working on the smart grid standard Energy Interoperation (and its profiled twin OpenADR). The normal mode in which this operates is that a [home, commercial building] is a Resource. A Resource may choose to respond to economic signals from the grid and use less energy. Service / Results / end of story. We call this the Energy Services Interface (ESI).

A complicating factor is that in many parts of the country, pure economic signals are not allowed. In these, to get rewards, there must be some level of not-quite-direct control of Devices inside a Resource. We call these Assets. Think of an Asset as a virtual device that’s a good place to start. An Asset may be a toaster, a water heater, or an entire production line in a factory. What matters is that a contract allows it to be exposed and its function “directly” monitored.

A potentially interesting spin on Assets is Distributed Energy Resources (DER). A home solar panel, or a roof-top wind turbine, or a grid integrated thermal storage system might all be Assets. In any case, Assets need only a constrained set of interactions (On, off, half speed, set thermostat to 76, is it running now, charge up, discharge, how much electricity is it generating now). Limited metadata is expected as well, largely to let Transmission operators deal with covarying Assets. 500 solar panels on the south side of town might be covarying Assets as the same clouds might take them all out at the same time.

Today, of course, Assets are covered by Tariffs, and this is all closely regulated. In the future, Assets may be offered to the market as tenders, contracted, and exposed.

I am considering how I would incorporate WS-DD and WS-DP into the ESI. The model is the secure proxy discovery of remote devices already incorporated into WS-DD, i.e., the ESI can choose which Assets to expose, and when to expose them. The ESI would them “take Assets off line” when they are not available for “direct” interaction. In this case, Direct is still mediated application exposing the ESI.

I think there are a limited number of profiles (less than 10) to define all possible Assets. An essential part of the profile is the potential Energy effects of the Asset. (Can respond in 10 minutes, and free up 15 KW of power, but cannot be called upon for more than 3 consecutive hours). These Energy Profiles are already largely defined within the EMIX work on Energy Market Resources.

There is similar work going on inside ASHRAE SPC 201, discussing the energy information that would be exposed by Systems in Industrial Sites, Commercial Buildings, and Homes. If we can make this work for Energy Interoperation, we can imagine a [home] energy manager that discovers the energy profiles of all systems in the house. Some of those Assets are later exposed for secure remote access.

I guess this all assumes that Devices might have more than one service, say an Operation Service, as a Printer exposes to me, or an Energy Service, which exposes how it uses Energy.

Toby, can you, or any member of the committee, spare me some time to discuss how this might work, and give me pointers into approaching the WS-DD work for this purpose. (Of course, I may be talking DPWS).

Thanks in advance