IEC 61850

IEC 61850 is an international standard for communication in substations and power systems. Unlike the older protocols it is not only a communication protocol but also a data modelling standard — it describes a device’s functions, data and behaviour in a standard structure.

inSCADA supports the MMS (Manufacturing Message Specification) communication layer of IEC 61850 in both the Client and the Server role.

Note

GOOSE and Sampled Values are not supported; communication is over MMS only.

About the standard

Where it is used

• Substations (the primary plant)
• Power generation plants
• Distribution automation
• Wind and solar plants
• Industrial energy management

What it gives you

• Vendor independence: IEDs from different manufacturers interoperate through a common data model
• Self-description: a device’s configuration can be discovered automatically from its SCL file
• An object-oriented data model: a physical device’s functions are represented by logical nodes
• Performance: fast data access over MMS

The IEC 61850 data model

IEC 61850 models a physical device as a hierarchy of logical parts:

An example object reference: IED1/LLN0.Mod.stVal

• IED1 — the physical device
• LLN0 — the logical node (LN0: the base node)
• Mod — the data object (Mode — the operating mode)
• stVal — the data attribute (status value)

Some logical nodes

Logical node	Description
LLN0	The logical device’s base node
LPHD	Physical device information
XCBR	Circuit breaker
XSWI	Disconnector
MMXU	Measurement unit (voltage, current, power)
CSWI	Switch control
PTOC	Overcurrent protection
PDIS	Distance protection

Functional constraint (FC)

Every data attribute is classified by a functional constraint, which states what the data is for:

FC	Meaning	Used for
ST	Status Information	Reading state
MX	Measurands (analogue values)	Reading measurements
CO	Control	Writing a command
SP	Setpoint	Writing a setpoint
SE	Setting Group Editable	Editing a setting group
CF	Configuration	Configuration data
DC	Description	Descriptive data
SG	Setting Group	A setting group
SV	Substitution	Substituted values
BL	Blocking	Blocking
OR	Operate Received	Operation-received information
RP	Unbuffered Reporting	Unbuffered reporting
BR	Buffered Reporting	Buffered reporting
EX	Extended Definition	An extended definition
SR	Service Response	Service response and tracking

Tip

In a typical SCADA application the three you will use most are ST (reading state), MX (reading measurements) and CO (writing control).

SCL (Substation Configuration Language)

IEC 61850 describes a device’s configuration in SCL files. SCL is an XML-based format carrying the device’s whole logical structure (LD, LN, DO, DA).

The file extensions:

• .icd — IED Capability Description (what the device can do)
• .scd — Substation Configuration Description (the plant’s configuration)
• .cid — Configured IED Description (a configured IED)

When you create the connection, inSCADA imports the SCL file and discovers the device’s data model from it.

The inSCADA data model

An IEC 61850 connection is configured in this hierarchy:

Supported data types

Data type	Description
Boolean	A single-bit value
Int8 / UInt8	An 8-bit integer
Int16 / UInt16	A 16-bit integer
Int32 / UInt32	A 32-bit integer
Int64	A 64-bit integer
Int128	A 128-bit integer
Float32	A 32-bit floating-point value
Float64	A 64-bit floating-point value
Visible String	An ASCII string
Unicode String	A Unicode string
Octet String	A byte string
Timestamp	A timestamp
Quality	Quality information
Double Bit Pos	A double-bit position (breaker or isolator state)
Check	Control validation
Tap Command	A tap-changer command

Sub-pages

• IEC 61850 Client — configuring the MMS client
• IEC 61850 Server — configuring the MMS server