The Smart Energy Grid Architecture Model (SGAM) is a three-dimensional architectural framework described in the IEC 63200 document. This model can be used to model the exchange of information between different entities located within the smart energy arena. The three dimensions are Domains, Zones, and Layers. Of primary interest for communication concepts are the Interoperability Layers – a slice through this 3-D model to show it more easily as two dimensions.

  • Domains identify a set of roles associated with 5 different areas of the energy grid: bulk generation, transmission, distribution, distributed energy resources, and customer
  • Zones represent the 6 hierarchical levels of power system management: Market, Enterprise, Operation, Station, Field, and Process
  • Layers represent the 5 aspects of information exchanges: Business Objectives, Functional Processes, Information Models, Communication Protocols, and Components

Communications involve more than the traditional concept of communication protocols (e.g. just bits and bytes going over a wire). The exchange of information involves multiple layers of interactions, involving business purposes down to the various media that could transport the information (including carrier pigeons). As an example, the GWAC Stack model and the SGAM model are different: the GWAC stack has 8 layers, while the IEC’s Smart Grid Architecture Model (SGAM) identifies 6 communication layers, but these two models were easily “mapped” to each other. The following are the primary layers:

  • Business Objectives, Economic/Regulatory Policy, Business Layer: This layer covers the business purposes for communications, including providing information for business decisions, meeting regulatory requirements, and requiring interoperability.
  • Business Context and Procedures, Function Layer: This layer addresses the functionality and use of the data within business contexts, such as “this collection of settings, monitored information, commands, defaults, timing, etc. provide the information exchange requirements for the voltage-reactive power function” or “this is the sequence of steps with specific data exchanged in each step for a DER to perform the frequency ride-through function”.
  • Semantic Understanding, Information Layer: This layer provides the meaning of the data and acts as “nouns” in the sense of “this is the three-phase rms voltage measurement on Feeder A in Substation Z”, “this is the maximum active power rating of DER B right now”, or “this is the updated setting for reactive power for power plant Y”.
  • Syntactic Interoperability, Application Layer: This layer provides the communication services and acts as “verbs” in the sense of “getting data”, “monitoring data”, “controlling data”, “setting data values”. It does not cover the meaning of the data, only the services.
  • Network Interoperability, Transport Layer: This layer transports the information, usually in message packets, from one end to the other end. This may involve going through multiple nodes, gateways, routers, etc.
  • Basic Connectivity; Component Layer: This layer encompasses the physical media, such as wires, wireless, fiber optics, coaxial cable, LANs, WANs.

IEC 61850-7-420 is the information model for Distributed Energy Resources, and those data objects can be mapped directly to different protocols, such as the IEC 61850-8-1 MMS protocol, the IEC 61850-8-2 XMPP protocol, the IEC 60870-5-104 (based on IEC 61850-8-1), and the IEEE 1815 (DNP3 protocol), based on the MESA Specification mapping.

IEC 61850-7-420 is also used by other protocols as a source of data objects, even though they modify the data objects to fit their protocols. Examples include IEEE 2030.5 for DER and SunSpec Modbus Specifications for DER. There are additional efforts on “harmonizing” the Common Information Model (CIM) with the IEC 61850-7-420 to provide support for DERMS and utility Energy Management Systems.