by K eith Gray, POWER Engineers – a member of WSP, USA
You will see in this article that IEC 61850 is a living standard that continues to evolve and expand, which leads to improved implementations of digital substations.
In this column, I am carrying on Christoph’s tradition of focusing the first article of the year on WG10 updates. The week of February 8th was our first meeting of 2026 in Seville, Spain. It was a great success and proved to be extremely productive, as is typical of these meetings. You will see in this article that IEC 61850 is a living standard that continues to evolve and expand, which leads to improved implementations of digital substations. For users, vendors, and system integrators, the outcomes of these meetings directly influence long term system maintainability, clarity of models, and alignment across domains.
IEC TC57 WG10 was busy in 2025 and published five documents: IEC TS 61850-6-3 Edition 1, IEC 61850-10 Edition 2 Amendment 1, IEC TR 61850-90-20 Edition 1, IEC TR 61850-90-21 Edition 1, and IEC TR 61850-90-30 Edition 1.
We also circulated various draft stages for another seven documents and initiated sixteen new work items, either updates to existing documents or new documents. Approximately every six months, WG10 publishes an update within the IEC, and this update contains all the details about the current status of all the documents. If you are an IEC member, you can see the latest iteration as document 57/2851/INF.
One area that generated seven of those 16 new work items is the separation of IEC 61850-7-4 into domain-specific parts. This separation is intended to allow models from different domains to have their own maintenance and release cycles. This is primarily an organizational change intended to improve long term manageability of the standard. The initial release of these documents extracted from part 7-4 are expected to be in 2026.
To be clear, there are no technical changes in this update, just the reorganization of the Logical Nodes (LNs) into separate parts will be in the next release.
Part 7-4 will remain a document, but its scope will be cut back to just the core data models. This includes the Abstract LNs and the System LNs (for example, DomainLN, LPHD, LLN0, and LGOS). A new document, 7-40, will contain the common LNs (for example, MMXU, IHMI, and GAPC).
Part 7-43 will contain the primary equipment LNs (for example, XCBR, XSWI, and KFAN).
Part 7-44 will contain the Instrument Transformer LNs (for example, TCTR and TVTR).
Part 7-400 will contain the substation automation LNs (for example, ATCC, CSWI, and CILO).
Part 7-401 will contain the protection and protection related LNs (for example, PDIF, PDIS, PTOC, RREC, and RBRF).
Part 7-440 will contain the power quality and metering LNs (for example, MMTR and QVTR).
These examples are illustrative and not meant to be exhaustive.
In addition to the split of part 7-4, work is continuing in creating a Unified Modeling Language (UML) model for the System Configuration description Language (SCL). The UML model will be used to generate the SCL schema (XSD) in future editions, starting with Part 6-1 Edition 1, which is just a renumbering of the existing Part 6.
Having the UML model will allow us to build upon it in areas such as IEC 61850-6-3, which describes how we can validate SCL files using the Object Constraint Language (OCL). The intention is to have the schema generated from the UML be functionally equivalent to the current scheme with no technical changes.
Finally, a new process for publishing TISSUEs has been agreed to by IEC. A corrigendum will be published for any part that has a TISSUE. This new process closes a couple of known gaps in distributing the latest version of the standard because it notifies those who already own the standard of the published TISSUEs.
It will also ensure that people who purchase the standard after the TISSUEs have been published receive the latest version.
There is a lot of work going on in all three Technical Areas (Communications, Engineering, and Modeling) that I cannot cover in this article. WG10 continues to produce high-quality and high-value work products that support and benefit the digital substation industry.
Topics such as validation using OCL will be explored in more detail in future issues.
Biography:
Keith Gray (P.E.) received his M.S. in Electrical Engineering from Southern Illinois University Edwardsville in 2005. He is a protection, automation, and control engineer with over two decades of experience working for POWER Engineers, a member of WSP. He has focused on digital substations and IEC 61850 since 2014 and is the co-convener of IEC TC57 WG10. He is currently participating in multiple CIGRÉ working groups covering various IEC 61850 topics and he is active in the UCA International Users Group IEC 61850 interoperability events. He is a licensed Professional Engineer in the state of Idaho.
