When defining network communication architecture, it’s worth considering using a mixture of both of these forms of active redundancy. I’m suggesting the use of a single-ring HSR for IEDs that share the same application, and a double star PRP to connect the overall large number of IEDs.
This idea of this recommended protection scheme is to gather the HSR rings with a PRP network optimized by two Redundant Boxes per interconnection:
These HSR rings are created by sub-application, such as per feeder or bay. This allows easy physical disconnections from the PRP network whenever needed.
This design mirrors the same communication principle as today’s relay to optically isolated inputs but with the advantage of an additional technological safeguard. When the two PRP fibers (or communication cables) from the RedBoxes are disconnected, all communications from that bay to the other ones stop. If the fibers or cables remain disconnected, the other IEDs or HMI trigger an alarm for that situation—which is not the case if a wire from a relay to an optically isolated input has not been reconnected.
Because both protocols are plug & play, no special engineering is necessary. Singly attached equipment such as a laptop or HMI can be connected to the PRP network.
Further, if equipment jams and overflows the network, the problem is limited to this single bay ring as normally filtered by the RedBoxes. Even if this is not the case, a simple remedy is to disconnect the two connections.
For more details, read my latest white paper about Optimizing Protection and Control Schemes Based on GOOSE Messages.