IEC 61850 and the Revolution in Substation Communications

The days of substations filled with heavy copper cables are coming to an end. Smart grids require smart communications. Peer-to-peer communication within and between substations is quickly becoming business as usual for power networks.

Facilitating this transition is IEC 61850. This global standard provides a completely new approach to automation and communication in substations.

What is IEC 61850?

IEC 61850 is a single unified protocol for substation automation. It allows devices from different vendors to talk to one another directly over an Ethernet connection. This operates in a similar way to a local area network (LAN) in an office.

The standard is divided into several parts dealing with data, communications, and compliance. Taken together, it enables distributed automation and significant information exchange. This is vital for the rollout of modern smart grids.

The Architecture: Abstract Data

The architecture of IEC 61850 is based on the principle of “abstract” data. This means data groupings and naming conventions are separated from the underlying protocols.

The result is a universal language. It stays the same regardless of which manufacturer made the device. Creating such a vendor-neutral standard is a major step forward for interoperability. It offers speed, security, and significant cost benefits.

Randolph Brazier, head of innovation and development at the Energy Networks Association, explains the impact: “With this standard… you can set up a LAN within either the control room or the whole substation. You essentially have a network like you would have in an office, and that allows devices within that substation to talk directly to each other.”

Key Benefits of the Standard

The advantages of switching to IEC 61850 are multiple and immediate:

Reduced Copper Cabling: Traditionally, devices used copper cables running between them. Now, there may be just one or two point-to-point cables connected to an Ethernet ring. This can save hundreds of thousands of pounds per substation and cut labor costs.
Interference Immunity: Communications happen over fiber optic cables, which are not susceptible to magnetic interference. Faults in the substation do not affect the data stream.
Interoperability: In the past, manufacturers often locked you into their ecosystem. With this common protocol, any device can talk to any other device.
Future-Proofing: When a device fails, it can be replaced with a new one that speaks the same language, rather than reinventing the whole communications system.
Improved Security: Signals are prioritized and repeated. Unlike old systems where a message could get lost due to a fault, this protocol ensures the signal gets through.

Technical Components: GOOSE and Ethernet

GOOSE Messaging

One of the most powerful features of the standard is GOOSE (Generic Object-Oriented Substation Event). These are high-speed messages optimized to be multicast over an Ethernet network.

GOOSE allows for digital representations of hardwired inputs/outputs (I/O). The major benefit is flexibility. Adding new logic variables requires the engineer to modify only the device configurations, not the physical wiring. This allows for complex, distributed protection schemes that were previously impossible.

Ethernet Architectures

Modern systems rely on fast Ethernet networks. These can be built within a substation or interconnected across dispersed sites. The correct selection of Ethernet switches—robust devices designed for harsh environments—enables various topologies like ring, star, or mixed architectures.

Redundancy Protocols: PRP vs. HSR

Reliability is non-negotiable in power networks. IEC 61850 supports advanced redundancy protocols defined in IEC 62439-3.

PRP (Parallel Redundant Protocol)

PRP is based on duplication. Any device is attached to two completely separate Ethernet networks (LANs).

The source sends a frame simultaneously on both LANs.
The destination uses the first one that arrives and discards the second.
Benefit: If one network fails, there is zero data loss and zero recovery time (0ms).
Cost: It requires more switches to build the double infrastructure.

HSR (High-Availability Seamless Redundancy)

HSR applies a similar principle but uses a ring topology. Data is sent in both directions around a single ring.

Benefit: It does not require additional switches, making it cheaper to deploy than PRP.
Limitation: It is generally limited to about 16 communicating devices because each device must pass along messages from others, consuming bandwidth.

Both solutions offer “plug and play” redundancy, ensuring that if an Intelligent Electronic Device (IED) fails, the rest of the network continues to operate safely.