IEC 61400-25

IEC 61400-25 is the wind-power extension of IEC 61850. It reuses the 61850 architecture — abstract data models, logical nodes, communication profiles — and adds wind-specific logical node classes (WROT for the rotor, WTRM for the transmission, WGEN for the generator, WCNV for the converter, WMET for meteorological sensing) so that a wind turbine generator presents the same interface shape to a control system as a conventional IED in a substation.

It is the standard that lets a wind farm be wired into the same SCADA / ADMS / EMS stack as the rest of the network, rather than being a vendor-proprietary island.

Why wind needed its own family

Wind turbines have device classes that don’t exist in conventional substations:

• The rotor has a pitch-angle controller, a speed sensor, an aerodynamic state.
• The transmission (gearbox or direct-drive) has temperatures, vibrations, lubricant condition.
• The generator has electrical and thermal state familiar to a substation engineer but mechanically coupled in ways a transformer is not.
• The converter (typically a back-to-back IGBT setup for variable-speed turbines) has its own switching state, harmonic profile, and grid-following or grid-forming logic.
• The meteorological mast measures wind speed, direction, temperature, pressure — inputs the turbine controller and the energy market both consume.

Forcing all of this into the substation-flavoured 61850 logical-node catalogue would have produced something unidiomatic. 61400-25-2 defines the wind-specific logical nodes that compose with 61850’s existing ones to describe a complete WTG.

What it carries over from 61850

Most of the 61850 architecture is unchanged:

• The hierarchical naming convention (Server / Logical Device / Logical Node / Data Object / Data Attribute).
• The publish/subscribe model for events.
• The use of SCL for engineering and configuration exchange.
• The mapping to MMS over TCP/IP for the client/server traffic.

A wind farm SCADA system using 61400-25 looks structurally like a substation SCADA system using 61850. That is the point.

Communication profile differences

61400-25-4 specifies multiple mappings, of which MMS over TCP/IP is the dominant one used at scale. Older deployments and some smaller turbines also expose data via web services (SOAP / XML) or OPC XML-DA, both of which were intended to be more friendly to the IT-side of the wind operator’s stack than MMS is to a typical IT engineer.

The web-services and XML-DA mappings have aged poorly — both are 2000s-vintage technologies that nobody is excited to integrate against in 2026 — and most new wind deployments default to the MMS profile, with 62351-3 and -4 for security on top.

Where the substation architect intersects it

For a transmission or distribution operator, wind farms are a connected source whose internal communications are someone else’s problem (the wind operator’s) but whose external interface to the grid SCADA is very much the operator’s business. That external interface — the substation that connects the wind farm to the transmission network — is conventional 61850 territory, but the data flowing through it from the wind farm uses 61400-25 logical nodes the operator’s SCADA may or may not understand.

The integration question that arises in practice is: does the operator’s ADMS consume the 61400-25 model directly, or does the wind farm gateway translate it into a more conventional 61850 substation profile? Both patterns exist. The first preserves more information; the second is simpler to integrate against legacy ADMS systems that don’t have 61400-25 logical-node libraries.

Why this matters now

The corpus’s transmission/distribution context historically did not need to think about 61400-25 — wind was a small fraction of the connected generation. By 2026 the GB transmission network is regularly run with wind providing more than half of demand for hours at a time, and the operational role of wind farms has shifted from “non-dispatchable injection” to “active grid participant providing reactive support, frequency response, and synthetic inertia”. That participation is mediated by the 61400-25 interface; an ADMS that does not understand it cannot dispatch the resource it is sitting beside.

61400-25 is one of the standards that the substation architect can no longer treat as someone else’s standard.