What Is IEC 61850?

IEC 61850 is an international family of standards developed for the automation of electrical power systems. It was developed particularly to facilitate the interoperability of protection relays, control devices, measurement devices, and other IED (Intelligent Electronic Device) devices used in substations.

In traditional systems, much of the information exchanged between devices could be transmitted through separate cables, vendor-specific protocols, or different communication methods. IEC 61850 aims to make devices from different manufacturers easier to integrate by defining their information within a standardized data model.

One of the most important features of IEC 61850 is that it does not simply define "which byte means what"; it also standardizes the meaning of information within the electrical system. This allows an electrical status, measurement, or protection function within a device to be represented using a standardized model.

Although IEC 61850 was initially developed primarily for substation automation, its use has expanded to areas such as distributed energy resources, hydroelectric and wind power plants, distribution automation, and other energy systems.

Why IEC 61850?

Standardized Communication

Enables IEDs, protection relays, control devices, and SCADA systems from different manufacturers to communicate through a standardized architecture.

Standardized Data Model

A standardized data model is used for electrical equipment and functions. This means that not only the value of the data, but also its meaning, is defined.

High-Speed Communication

Communication services such as GOOSE enable very fast device-to-device communication for protection, interlocking, and control applications.

Vendor-Neutral Architecture

Standardized data models and engineering methods make it easier to use devices from different manufacturers within the same automation system.

Ethernet-Based Communication

IEC 61850-based systems can use modern Ethernet networks to create high-speed and flexible communication infrastructures.

Standardized Engineering

SCL files allow IED capabilities, system structures, and communication information between devices to be defined in a standardized format.

IEC 61850 Addressing for EOS Software (B#)

In the EOS SCADA IEC 61850 client, the data address is created using the IEC 61850 Logical Device, Logical Node, Data Object, and Data Attribute structure.

B#LD:LN:DO:SDO:SDO:FC:FC:FC:DATA_TYPE

The address structure specifies the Logical Device, Logical Node, Data Object, and Data Attribute information, as well as the functional constraints and data type.

For example:

B#TestIEDGenericIO:GGIO1:AnIn1:mag.f:t:q:MX:MX:MX:FLOAT

Values such as MX, ST, SP, CO, OR, CF, DC, SG, SE, CB, ALL, and NONE can be used as functional constraints.

Supported data types include BOOLEAN, INTEGER, FLOAT, and BITSTRING.

What Is an IED?

One of the most important concepts in IEC 61850 systems is the IED (Intelligent Electronic Device).

An IED can be a protection relay, bay control unit, measurement device, control device, or any intelligent device capable of collecting data from an electrical system and sharing that information over a communication network.

For example, a protection relay in a substation can measure current and voltage values, monitor the status of a circuit breaker, execute protection functions, and transmit the resulting information to other devices or a SCADA system through the IEC 61850 network.

A Simple Example

Whether a circuit breaker is open or closed is not considered simply as "0" or "1" in IEC 61850. This information is represented within a standardized data model associated with a specific piece of electrical equipment and its function.

IEC 61850 Data Model

One of the major differences between IEC 61850 and many other industrial protocols is its standardized data model. This model provides a common structure for defining information within devices.

In the IEC 61850 data model, devices and functions are represented at several hierarchical levels. The most common concepts include Logical Device, Logical Node, Data Object, and Data Attribute.

Logical Device

A logical device structure within an IED that represents a specific group of functions.

Logical Node

A standardized logical node representing a specific electrical function or piece of equipment.

For example, XCBR can represent a circuit breaker, XSWI a disconnector, MMXU three-phase measurements, and PTOC overcurrent protection.

Data Object

A data object within a Logical Node that represents a specific piece of information or status.

Data Attribute

Represents more detailed properties of a data object. Information such as value, quality, and timestamp can be found at this level.

IEC 61850 Communication Services

Different communication mechanisms are used in IEC 61850 systems for different purposes. The best-known ones are MMS, GOOSE, and Sampled Values.

MMS

Manufacturing Message Specification (MMS) is one of the fundamental mechanisms used for client-server communication in IEC 61850 systems.

SCADA systems and control centers can read measurement values from IEDs, monitor status information, receive events, and perform control operations when properly authorized.

  • IED data reading
  • Status monitoring
  • Measurement acquisition
  • Report mechanisms
  • Control operations
  • File transfer

GOOSE

GOOSE (Generic Object Oriented Substation Event) is a communication mechanism used to transmit events and status information between IEDs with very low latency.

It can enable direct communication between devices for applications such as protection tripping, interlocking, and fast control.

  • Protection trip signals
  • Interlocking
  • Circuit breaker status
  • Fast control signals
  • IED-to-IED communication
  • Multicast Ethernet communication

Sampled Values

Sampled Values (SV) enable sampled values of analog electrical quantities to be transmitted over a communication network.

They are particularly used for transmitting measurements from current and voltage transformers into digital systems and for digital substation architectures.

  • Current samples
  • Voltage samples
  • Process Bus applications
  • Merging Unit communication
  • Digital measurement

Station Bus and Process Bus

In IEC 61850-based digital substations, the communication infrastructure can generally be considered at different levels. Two of the most commonly used concepts are Station Bus and Process Bus.

Station Bus

Used for communication between IEDs, SCADA systems, HMIs, gateways, engineering stations, and other higher-level systems.

MMS-based communication plays an important role at this level.

Process Bus

Provides digital transmission of measurement and control information at the process level.

High-speed communication mechanisms such as Sampled Values and GOOSE play an important role in Process Bus applications.

What is SCL?

SCL (Substation Configuration Language) is an XML-based standardized language used for the engineering and configuration of IEC 61850 systems.

SCL allows IED capabilities, the structure of devices within the system, communication connections, and various configuration parameters to be defined in a standardized file format.

This approach aims to facilitate the exchange of configuration information between engineering tools from different manufacturers and to standardize the system engineering process.

ICD

IED Capability Description. Describes the capabilities of an IED and the functions it supports.

SSD

System Specification Description. Used to describe the system and the functions required for the substation.

SCD

Substation Configuration Description. Contains the overall configuration of the substation and the relationships between IEDs.

CID

Configured IED Description. Contains the configuration information prepared for a specific IED.

How Does GOOSE Work?

In GOOSE communication, information published by an IED can be received by other relevant IEDs on the network. Unlike the traditional client-server approach, this structure is based on a fast publish/subscribe model.

For example, when a protection relay detects a fault, it can send a GOOSE message to another IED or control device to initiate the opening of a circuit breaker.

The retransmission of GOOSE messages and the use of Ethernet multicast communication help critical events to be transmitted quickly and reliably.

Example Application

In a substation, Protection Relay A detects a fault. Relay A publishes a GOOSE message. Relay B receives this message, executes the required control logic, and can initiate the opening of the associated circuit breaker.

Sampled Values and the Digital Substation

In conventional substations, analog signals from current and voltage transformers are transmitted to protection and measurement devices through various copper cables.

In an IEC 61850-based digital substation, these measurements can instead be digitized and transmitted over the communication network.

Devices known as Merging Units play an important role in this process. A Merging Unit can sample analog electrical quantities and generate a Sampled Values stream.

  • Digitization of current measurements
  • Digitization of voltage measurements
  • Measurement transmission over Ethernet
  • Process Bus architecture
  • Digital protection applications
  • Digital measurement and monitoring

IEC 61850 and SCADA

IEC 61850 is an important technology for SCADA systems, particularly for acquiring data from and monitoring IEDs installed in substations.

A SCADA system can communicate with protection relays, bay control units, and other IEDs through IEC 61850 and transfer measurement, status, alarm, event, and control information to the central system.

This allows SCADA operators to monitor not only raw data received from a device, but also meaningful electrical information represented within the IEC 61850 data model.

Monitoring

IED statuses, measurements, circuit breaker and disconnector information can be monitored on SCADA screens.

Alarms and Events

Protection and device status information can be transferred to alarm and event management systems.

Measurements and Trends

Current, voltage, power, frequency, and other measurements can be archived in the SCADA system and displayed as trends.

Control

When appropriate authorization and security conditions are provided, control operations can be performed through the relevant IEDs.

How Is IEC 61850 Different from Traditional Communication?

One of the most important differences of IEC 61850 is that communication is not regarded merely as a means of transferring data. The meaning of devices and electrical functions is also defined within a standardized data model.

Feature Traditional Approach IEC 61850
Data Model Usually device- or manufacturer-specific Standardized data model
Device Communication Dependent on the protocol and application Standardized services and models
Fast Event Communication Separate wiring or dedicated solutions GOOSE
Analog Measurement Transfer Analog wiring Sampled Values
Engineering Manufacturer-specific tools SCL-based configuration

IEC 61850 Network Architecture

The communication infrastructure is extremely important in IEC 61850-based systems. For time-critical communication such as GOOSE and Sampled Values, network design, switching equipment capabilities, redundancy, and time synchronization must be carefully considered.

Large and critical systems may require dedicated engineering studies for network topology, redundancy, time synchronization, and network performance.

  • Ethernet switches
  • VLANs and traffic prioritization
  • Multicast communication
  • Network redundancy
  • Time synchronization
  • Network monitoring

IEC 61850 and Cybersecurity

As power systems become increasingly connected to communication networks, cybersecurity has become an important part of system design.

Within the IEC 61850 ecosystem, cybersecurity is addressed together with the IEC 62351 family of standards.

When designing an IEC 61850 network for an actual power facility, it is important to consider not only communication functionality, but also access control, network segmentation, reliability, device security, monitoring, and secure engineering processes.

Where Is IEC 61850 Used?

Substations

IEC 61850 can be used in protection, control, and automation systems of transmission and distribution substations.

Power Generation Facilities

It can be used in electrical automation applications in hydroelectric, thermal, wind, and other power generation facilities.

Distributed Energy Resources

It can be used for integrating distributed energy resources such as solar and wind power into the electrical grid.

Distribution Automation

It can be used for monitoring, control, and automation applications in electrical distribution systems.

Advantages of IEC 61850

  • Facilitates interoperability between devices from different manufacturers.
  • Provides a standardized data model for representing electrical information.
  • Enables fast peer-to-peer event communication between devices using GOOSE.
  • Enables analog measurements to be transmitted over a digital network using Sampled Values.
  • SCL can help standardize engineering and device configuration processes.
  • Can help reduce the amount of wiring and traditional point-to-point connections.
  • Enables the use of modern Ethernet infrastructures and network redundancy.

What You Should Know When Learning IEC 61850

Learning IEC 61850 involves much more than simply connecting to an IP address and reading data. Its data model, Logical Node structure, communication services, and engineering processes need to be understood together.

Learning the following concepts provides a good starting point for understanding IEC 61850 systems:

  • IED
  • Logical Device
  • Logical Node
  • Data Object
  • Data Attribute
  • DataSet
  • Report
  • MMS
  • GOOSE
  • Sampled Values
  • SCL
  • ICD
  • SSD
  • SCD
  • CID
  • Station Bus
  • Process Bus

IEC 61850 Tools

Tools that can be used to learn, test, analyze, and develop IEC 61850 systems will be shared in this section.

This section will be expanded over time with free tools for analyzing IEC 61850 communication, testing IED devices, analyzing GOOSE and Sampled Values traffic, viewing SCL files, and developing IEC 61850 applications.

IEC 61850 Tools Coming Soon

This section is currently under development. Free IEC 61850 utilities, testing tools, example applications, and developer tools will be shared here.

IEC 61850 in Brief

IEC 61850 is a comprehensive family of standards designed not only to enable communication between devices in power systems, but also to standardize the modeling of electrical information and provide a common engineering approach for system configuration.

MMS plays an important role in SCADA and client-server-based data exchange; GOOSE is used for fast peer-to-peer event and control communication; while Sampled Values is used to transmit digitized current and voltage measurements.

This architecture makes IEC 61850 an important standard for modern power automation, particularly in terms of high-speed communication, standardized data modeling, interoperability between manufacturers, and the development of digital substation architectures.