IEC 61970 (EMS-API) Core CIM — transmission
The energy management system application program interface. IEC 61970-301 defines the core Common Information Model; the -45x parts define CIM/XML model exchange. The transmission-grid heart of CIM.
IEC 61970 / 61968
CIM, the grid's common information model
IEC 61970 and IEC 61968 define the Common Information Model (CIM): a shared, UML-based description of the objects in a power system. IEC 61970 covers the energy management system (transmission); IEC 61968 covers distribution management; IEC 62325 covers markets. Together they let utility systems exchange grid models without point-to-point mapping — the basis of Europe's CGMES.
Document structure
IEC 61968 CIM for distribution (DMS)
Application integration at electric utilities. Extends the core CIM with distribution packages — assets, work, customers, metering, network operations — and IEC 61968-100 for message integration.
IEC 62325 CIM for markets
A framework for energy market communications built on CIM, standardising the documents exchanged between market participants and operators.
CGMES (ENTSO-E profile) European grid model exchange
The Common Grid Model Exchange Standard — an ENTSO-E profile of CIM used by European TSOs to exchange interconnected network models. The most visible operational use of CIM.
Key concepts
- Common Information Model (CIM)
(CIM) - A UML-based, vendor-neutral model of every major object in an electric utility — lines, transformers, breakers, measurements, assets. It gives different systems one shared vocabulary for the same network.
- One model, three domains
- IEC 61970 serves the EMS (transmission), IEC 61968 the DMS (distribution), IEC 62325 the market. They share the same core model and extend it, so a transformer means the same thing everywhere.
- CIM/XML model exchange
- Networks are serialised as CIM/XML (RDF) files and exchanged whole — a complete, self-describing grid model — instead of mapping field-by-field between systems. This is what removes brittle point-to-point integration.
- Profiles and CGMES
- The full CIM is huge, so real exchanges use profiles — agreed subsets for a purpose. CGMES is the ENTSO-E profile that lets European TSOs merge their network models for interconnected operation and capacity calculation.
- Semantic interoperability
- CIM targets meaning, not just format. Two systems agreeing on CIM agree on what the data represents, which is why it underpins EMS, DMS, ADMS, GIS and market integration alike.
- CIM vs IEC 61850
- 61850 models data inside the substation, on the wire, in real time. CIM models the whole network for enterprise and control-centre applications. TC 57 maintains both and is harmonising the boundary between them.
Notes & guidance
One shared model for the whole grid
A utility runs dozens of systems — energy management, distribution management, GIS, asset management, markets — and each has its own idea of what a “transformer” or a “feeder” is. Integrating them one pair at a time is endless and brittle. The Common Information Model (CIM), defined by IEC 61970 and IEC 61968, replaces that with one shared, vendor-neutral model of the power system.
Three series, one model
CIM is split by domain but built on a common core. IEC 61970 is the energy management system API: its part 61970-301 defines the core CIM, and the -45x parts define how a network is exchanged as CIM/XML. IEC 61968 extends that core for distribution — assets, work, customers, metering, network operations — and adds message integration in 61968-100. IEC 62325 extends it again for electricity markets. Because all three share the same core, a transformer modelled in the EMS means the same thing in the DMS and in the market.
Profiles and CGMES
The complete CIM is far too large to use whole, so real exchanges rely on profiles — agreed subsets for a specific purpose. The most important in Europe is CGMES (Common Grid Model Exchange Standard), the ENTSO-E profile that lets transmission operators merge their individual network models into one interconnected model for operation, capacity calculation and planning. CGMES is the clearest proof that CIM is operational, not academic.
CIM versus IEC 61850
CIM is often set against IEC 61850, but they live at different levels. 61850 models data inside the substation, on the wire, in real time; CIM models the whole network for control-centre and enterprise applications. Both are maintained by IEC TC 57, which is harmonising their boundary. Alongside them, OPC UA (IEC 62541) carries data to analytics platforms, ISO 55000 governs the assets the model describes, and IEC 62443 secures the systems that exchange it.
Applicable industries
- Transmission and distribution system operators (TSO/DSO)
- EMS, DMS and ADMS software vendors
- Electricity market operators and exchanges
- GIS, asset-management and network-planning systems