The document proposes automating the design of smart grid solution architectures using a formal model. It introduces an approach used in healthcare to define integration profiles and transactions between actors. This is formalized to automatically evaluate interdependencies and quality attributes. As a proof of concept, secure message exchange in a virtual power plant use case is modeled to check throughput requirements. Future work aims to integrate additional smart grid reference architecture components and quality metrics into the formal evaluation.

1. Automating Smart Grid Solution Architecture
Design
Massimiliano Masi,
Tanja Pavleska (Jozef Stefan Institute, SLO),
Helder Aranha (esPAP, PT)
massimiliano.masi@tiani-spirit.com
IEEE SmartGridComm 2018, Aalborg, October 29, 2018

2. The problem of interoperability
Smart Grids face great interoperability challenges.
Accomodate and coordinate a great number of power sources
featuring different technologies
Virtual Power Plants (VPPs) are a major representative
Interoperability is seen as the key enabler of smart grid.
Masi et al.: SG Architecture CC Massimiliano Masi IEEE SmartGridComm 2018, Aalborg, October 29, 2018 2/15

3. Using standards
Using standards is not enough
“standards alone are not enough to guarantee
interoperability” (G. Lewis)
“The nice thing about standards is that you have so many to
choose from” (A. Tanenbaum)
61850 vs 60870-5-104
Masi et al.: SG Architecture CC Massimiliano Masi IEEE SmartGridComm 2018, Aalborg, October 29, 2018 3/15

4. The SGAM
Smart Grids Architectural Model
Architecture-wise, the design of interoperable energy systems
is supported by SGAM
Introduced by ETSI/CEN/CENELEC in 2011 under the EU
Mandate M/490
Several attempts to build smart grids using SGAM
Design is a full manual task (and error-prone):
Architect shall evaluate all the interdependencies amongst
architectural constructs (e.g., components)
Consider all variability points to provide a cohesive and
interoperable solution
By creating a formal model, we introduce a semantic construct
that automatically evaluates the interdependencies
Masi et al.: SG Architecture CC Massimiliano Masi IEEE SmartGridComm 2018, Aalborg, October 29, 2018 4/15

5. Our Contribution
Our path
Evaluate the use of a cross-sectorial architectural approach
used in other verticals, apply it to SmartGrids using SGAM to
ease solution refactor and design
Provide a formal account of it (alternative syntax and
semantics in denotational style, amenable to automation)
Implement it as Eclipse plugin
Evaluate quality attributes on the resulting architecture
(ex-ante, ex-post) using a logic formula satisfiability solver
(Microsoft Z3)
Masi et al.: SG Architecture CC Massimiliano Masi IEEE SmartGridComm 2018, Aalborg, October 29, 2018 5/15

6. The methodological support
We took inspiration from the CEF and the e-SENS project: we
formalised the architectural model which is in use in eHealth since
decades.
Masi et al.: SG Architecture CC Massimiliano Masi IEEE SmartGridComm 2018, Aalborg, October 29, 2018 6/15

7. Concepts
Reference Architecture is the generic architecture providing
guidelines and options for developing specific architectures
and solution implementations. Here it refers to the set of all
available VPP-related profiles used to build a solution
architecture.
Solution Architecture describes the specific business
operations/activities and the ways in which information
systems and technology support them. It typically applies to a
single project/organization.
Masi et al.: SG Architecture CC Massimiliano Masi IEEE SmartGridComm 2018, Aalborg, October 29, 2018 7/15

8. Concepts / 2
Actor is a functional component of the healthcare, or energy,
organization.
Transaction is a standards-based specification of the
interactions between IHE Actors.
Profile is a high-level functional unit composed of related IHE
Transactions, with the capacity to address specific IT
infrastructure requirements for a single case.
Masi et al.: SG Architecture CC Massimiliano Masi IEEE SmartGridComm 2018, Aalborg, October 29, 2018 8/15

9. Formal Account
We define a grouping function G which takes the integration
profiles previously chosen as input and returns a solution
architecture comprising those profiles and their dependencies.
G P1, . . . , Pn (r) = n
i=1G Pi , ˜P (r), ∀ ˜P ∈ A Pi (r) (1)
By using this approach we enable the evaluation of quality
attributes (e.g., Availability, Security aspects / Cross Cutting
Concerns (through RMIAS)) in the formal model
Masi et al.: SG Architecture CC Massimiliano Masi IEEE SmartGridComm 2018, Aalborg, October 29, 2018 9/15

10. A Smart Grid Use Case
We applied our formal model to a VPP / DEUs use case using
61850 (inspired by ieasaustria.at).
We defined a Functional SCHedule profile (FSCH), dependent
on Evidence and Node Authentication (ENA), providing TLS
We defined a measurement (MMXU) profile
We added a throughput metric
ENA as variability point: software TLS 1000 message/sec,
hardware TLS 3000 messages/sec
Applying our methodology
We grouped FSCH and MMXU and we obtained a solution
architecture for secure message exchange (automatically
evaluating the cross cutting concern)
We have a SMT-LIB file that can answer the question ”does
my architecture support 2000 messages/sec?”
Masi et al.: SG Architecture CC Massimiliano Masi IEEE SmartGridComm 2018, Aalborg, October 29, 2018 10/15

11. Towards the solution architecture
Masi et al.: SG Architecture CC Massimiliano Masi IEEE SmartGridComm 2018, Aalborg, October 29, 2018 11/15

12. Summary
Summary of our contributions
Conjectured that interoperability is compelling (and can’t be
achieved using standards)
Introduced the model use in healthcare since decades (IHE)
Provided and implemented a formal account of the model
enabling semi-automatic creation of solution architectures
Provided a framework based on SMT-LIB to evaluate quality
attributes ex-ante and ex-post
Applied to a Virtual Power Plant use case
Masi et al.: SG Architecture CC Massimiliano Masi IEEE SmartGridComm 2018, Aalborg, October 29, 2018 12/15

13. Future work
Add a function to handle the SGAM BAP to remove
variability and automatically create new BAP
Define a constraint model to enable on-the-fly evaluation of
quality attributes
Apply automatically the RMIAS model
Masi et al.: SG Architecture CC Massimiliano Masi IEEE SmartGridComm 2018, Aalborg, October 29, 2018 13/15

14. Input from Attendees / Discussion
Masi et al.: SG Architecture CC Massimiliano Masi IEEE SmartGridComm 2018, Aalborg, October 29, 2018 14/15

15. Thank You
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