IEC 61850 Edition 1 vs 2 vs 2.1: differences

The three editions over time

IEC 61850 is not one document: it is a series of parts that are published and amended separately. Speaking of an «edition» is therefore a useful simplification.

The table of parts with their current editions is in standards for substation communications and time synchronization.

What Edition 1 brought

The first edition defined what is taken for granted today: the data model with logical nodes, the abstract services, their mapping to MMS and GOOSE messages, sampled values, and the SCL configuration language. Its title referred to communication networks and systems in substations.

In the field, Edition 1 left gray areas: quality handling, test mode and some SCL details were open to interpretation, and each manufacturer resolved them its own way.

What changed in Edition 2

• Scope. The title went from «substations» to «power utility automation». Power plants, distributed energy resources and communication outside the substation were included.
• Test mode and simulation. The logical device modes were organized (on, blocked, test, test/blocked) and simulation was added: an IED can accept GOOSE and SV messages flagged as simulated instead of the real ones, to test with logical isolation. The simulated message is identical to the real one except for the simulation flag in its header.
• Subscription supervision. The logical nodes LGOS (GOOSE subscription) and LSVS (SV subscription) let the IED itself supervise whether each expected message arrives.
• Quality. Mandatory handling of data quality in GOOSE was clarified.
• New logical nodes and data classes, for example for power quality and equipment condition monitoring.
• SCL. New file types and rules were added for exchange between tools from different manufacturers. See SCL files.

The test modes are explained in more detail in the IEC 61850 digital substation guide.

What Edition 2.1 is

In 2020, Amendment 1 to several parts of Edition 2 was published: 7-1 to 7-4, 8-1 and 9-2, among others. IEC sells each part as a consolidated version of Edition 2 with its amendment, and the market calls it Edition 2.1. It fixes errata, clarifies behaviors and extends the model. Recent relays from the main manufacturers offer it, sometimes as an ordering option.

Problems when mixing editions in an expansion

The typical situation is a substation with Edition 1 IEDs to which bays with Edition 2 or 2.1 IEDs are added. What usually fails:

• Configuration tools. One manufacturer’s tool may not import the SCL file of another edition, or may not convert an IED’s configuration file between editions.
• New logical nodes and data that the older IED does not understand when it subscribes.
• Test mode. An Edition 2 IED in test mode publishes with the test flag; an Edition 1 IED may interpret it differently and accept or reject the message unexpectedly.
• Quality. An IED that flags questionable quality can make a subscriber of another edition discard the data, or use it when it should not.
• Names and lengths of objects and references that changed from one edition to the next.

None of this prevents coexistence. It takes engineering: checking the conformance of each IED, preparing the system configuration with a tool that supports both editions, and testing every real exchange.

How to specify the edition in a new project

In a new project it is sensible to require a single edition for all IEDs, normally the most recent one offered by the selected manufacturers, and to require that the system configuration tool supports it. In an expansion, the specification should state which existing IEDs the new ones will exchange messages with, and ask the vendor to demonstrate that interoperability before delivery.

What to check in the conformance documents

• Conformance certificate: IEC 61850 edition tested, version of the UCA International Users Group test procedure, laboratory and certificate level.
• PICS: which services the IED supports (reports, GOOSE, SV, files, control).
• MICS: which logical nodes and data it implements.
• TICS: which technical issues of the standard it implements.
• PIXIT: additional information needed for testing, such as limits, timings and vendor-specific behaviors.

IEC 61850 Part 10 defines conformance testing, and these documents are its basis.

IEC 61850 integration with Tiza Group

Expansions with IEDs of different editions and manufacturers are part of the daily work of our IEC 61850 engineering team: we check conformance, prepare the SCD and test each subscription, in medium-, high- and extra-high-voltage substations and industry, in Colombia, or elsewhere on request. Before starting, you can see which IED publishes and who subscribes in your SCD with our free IEC 61850 SCL viewer tool. If the change is in a relay’s configuration, we make it worldwide through remote relay configuration. Write to us.

Related guides

• IEC 61850 test mode: Mod, Beh, Sim and the test bit
• Configuration management: settings and SCD versions
• Migrating from 103, 101 or Modbus to IEC 61850
• Top-down and bottom-up IEC 61850 engineering: SSD to CID
• Substation communications by voltage level: MV, HV, EHV

References

• IEC 61850 (series), Editions 1 and 2, and the 2020 amendments to Parts 7-1, 7-2, 7-3, 7-4, 8-1 and 9-2.
• IEC 61850-7-4: logical node classes, including LGOS and LSVS.
• IEC 61850-6: SCL configuration language.
• IEC 61850-10: conformance testing.
• UCA International Users Group: IEC 61850 conformance test procedures.

Frequently asked questions