Smart grids collect a wealth of intelligence, beginning at the edge with Intelligent Electronic Devices (IEDs) that collect valuable information such as fault location, relay targets and customer usage in increasingly fine granularity which then is transmitted to the central control area to support the smart grid. Protective relays, meters, remote terminal units, LTC/regulator controllers, and predictive maintenance equipment also are becoming rich sources of data that can be made readily available to remote users. This new information requires increased communications bandwidth and a secure strategy for transporting the information to its destination points throughout the utility.

As power utility stakeholders address the challenges of creating end-to-end security for their smart grids, operations groups can benefit from a “Zones of Protection” strategy protection relay engineers have employed for some time to keep utility grids and equipment safe from fault and system unbalances.

In deploying the Zones of Protections, operations groups divide the grid into zones and provide each with its own protection scheme; overlapping zones provide backup protection. Key to the successful deployment of the Zones of Protection strategy is Ethernet, which is an ideal protocol for supporting communications Zones of Protection to address the rich information that is collected in the course of operation today. The figure depicts a typical substation with overlapping substation Zones of Protection, which provide backup protection should a primary zone fail.


In Figure 1, there are five Zone of Protection. Zones cover each feeder breaker (blue dotted lines), each low-side bus, each transformer (green dotted lines), each high-side bus and each incoming transmission Line (yellow dotted lines). The Transformer Zone acts as a primary zone for faults internal to the transformer and a backup zone is primary to faults on the low-side bus and feeders.

As the amount of information increases, the benefits of Ethernet-base transport become increasingly clear. Ethernet provides a seamless integration of networks on the corporate and operations side; in fact, it is the only transport protocol that supports an integrated IP communications strategy from the smart grid—and data generated in the substation itself—to the central office. Ethernet makes it easy to build a powerful cyber—and physical—security umbrella.

To learn more about Ethernet architectures with multiple zones of protection, check out Substation Security with Strategic Zones of Protection – Part 2.

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