Harnessing IEC 61850: Efficient, Robust Substation Control

Communication between devices is crucial in utility control systems—even basic serial communication between controllers and devices like relays and transformers.

As these systems increase in complexity, standardized approaches to communication become critical to ensure compatibility and communication.

While standardized protocols like Modbus RTU and Modbus TCP organize communication, they don't greatly improve how data is managed. Identifying important data and handling system issues remained difficult.

But this changed when DNP3 protocol was introduced in 1993 to help utilities classify and manage data efficiently, especially in substations.

Today, however—more than three decades years later—the future of modern substation performance lies with IEC 61850, which aims to further improve data communication and handling.

What is IEC 61850?

IEC 61850 is an international standard for communication networks and systems in power utility automation, encompassing power generation, transmission and distribution.

It defines a framework of parameters, functions and features that enable devices from different manufacturers to work together to ensure efficient communication.

Unlike other communication protocols, IEC 61850 specifies not only the communication process but also the structure in which data must be stored and managed in participating devices. These devices, known as intelligent electronic devices (IEDs), can replace the need for redundant control devices, such as remote terminal units (RTUs) and programmable logic controllers (PLCs).

IEC 61850’s information model is categorized into five levels:

1. Server Level: corresponds to the IED and represents the actual communicating device, encompassing all its informational properties.
   
   
2. Logical Device Level: within the server level, it represents a controllable device or function of the IED, such as a relay in a switchgear.
   
   
3. Logical Node Level: represents a functional unit of the logical device, like a measurement unit or a circuit breaker.
   
   
4. Data Object Level: contains data objects, which are collections of related data of distinct types, sizes or structures.
   
   
5. Data Attribute Level: actual data captured within the data attributes.

This standardized approach enables asset-to-asset communication, eliminating redundant control devices and improving data handling.

IEC 61850 also:

• Facilitates integration of different devices in control applications to improve safety and resilience
  
  
• Supports time-sensitive control data so critical information is prioritized and transmitted with minimal latency to maintain power system reliability and stability
  
  
• Provides a unified framework that enhances interoperability, reduces integration costs and simplifies modern technology deployment

By adopting IEC 61850, utilities can futureproof their infrastructure and improve operational efficiency.

How IEC 61850 drives substation efficiency

IEC 61850’s standardized data structure enhances substation communication and coordination through three key messaging functions:

• Manufacturing Message Specification (MMS)
• Generic Object-Oriented Substation Event (GOOSE)
• Reporting

MMS uses an efficient binary protocol to give devices a way to communicate quickly and efficiently. IEC 61850 organizes data into different security levels to enhance data security and management. For example, regular measurement data can use the less resource-intensive MMS, while sensitive control data can use SecureMMS.

GOOSE provides real-time, peer-to-peer communication so control devices can perform interdependent tasks without a central control unit. This supports critical functions like fault location, analysis and protection coordination to boost substation reliability and efficiency.

Reporting transmits specific data subsets to higher-level systems when relevant events (faults or disturbances) occur. This reduces processing demands and network load, ensuring that only essential information is communicated during crucial moments.

Improving efficiency and reliability for better substation operation

IEC 61850 offers features that significantly enhance the efficiency and reliability of substation operation and maintenance.

For flexibility and futureproofing, IEC 61850’s Abstract Communication Service Interface (ACSI) separates how devices talk to each other (communication stack) from how they’re controlled and managed (control model).

This makes application modifications and enhancements possible without affecting communication protocols. Scalability and adaptation to support modern technologies are possible, enabling upgrades and expansions without major overhauls.

IEC 61850 also provides robust diagnostics and monitoring so operators can resolve issues quickly to reduce downtime.

The standard’s Sampled Values (SV) protocol rapidly exchanges digitized power system measurements like voltage and current samples between substation devices over an Ethernet network. This reduces traditional wiring needs, simplifies installation and improves measurement accuracy and synchronization.

Finally, its Substation Configuration Language (SCL) allows devices to describe their own capabilities and configurations. This simplifies configuration, reduces the potential for human error and speeds up deployment and maintenance.

Designing resilient control networks

To help IEDs manage key control tasks in substations, IEC 61850 establishes strict rules to ensure a strong, reliable network.

Devices are synchronized using precision time protocol (PTP), which ensures that data is current and relevant. GOOSE enables seamless, timely exchange of information between devices. Critical data from process devices, such as transformers and switchgears, is constantly transmitted as real and sampled values. Due to the importance of this data, especially on the process bus that carries measurement traffic, seamless redundancy essential. The system cannot tolerate frame loss.

IEC 61850 supports resilient control networks through features like parallel redundancy protocol (PRP) and high-availability seamless redundancy (HSR). Enhanced fault tolerance is achieved through PRP and HSR, which provide alternative paths for data transmission to increase resilience and ensure quick recovery mechanisms to minimize data loss. They ensure robust communication even during network failure.

These two protocols are embedded in IEDs that function as dual attached nodes (DANs). IEDs with embedded PRP and HSR capabilities simplify network design and enhance reliability by enabling built-in redundancy without additional hardware.

Parallel Redundancy Protocol (PRP)

• Redundancy: Uses two independent network paths (LAN A and LAN B).
  
  
• Simultaneous Transmission: Sends duplicate data over both paths.
  
  
• Zero Recovery Time: Ensures uninterrupted operation during network failures.
  
  
• Data Integrity: Processes the first received packet, discarding duplicates.

High-Availability Seamless Redundancy (HSR)

• Ring Topology: Connects each IED in a closed loop.
  
  
• Dual Frame Transmission: Sends duplicate frames in both directions around the ring.
  
  
• Fault Isolation: Quickly isolates faults and reroutes data to maintain communication.
  
  
• Network Integrity: Ensures continuous, high-availability communication for resilient control networks.

By incorporating PRP and HSR features, IEC 61850 ensures that substation control networks are highly resilient and can maintain reliable, uninterrupted operation even under fault conditions.

Powering future advancements in utility performance

As you adopt IEC 61850 to revolutionize substation communication, Belden helps you improve data handling, interoperability and network resilience so your substations operate efficiently and reliably.

Our Customer Innovation Centers, run by power transmission and distribution experts who serve as invaluable technical resources, collaborate with you to develop complete connection solutions tailored to your scenarios and needs.

We can help you power future advancements in utility automation.

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