5.5 SELF HEALING PROTOCOL
The Self-Healing Protocol (SHP) implemented in the REB is a proprietary protocol that responds to the constraints
of critical time applications such as the GOOSE messaging of IEC 61850.
It is designed, primarily, to be used on P
ACiS Substation Automation Systems that employ the C264-SWR212
and/or H35x switches.
SHP is applied to double-ring network topologies. If adjacent devices detect a break in the ring, then they re-route
communication traffic to restore communication as outlined in the figure below.
C264
Px4x
MiCOM
H35
C264
Px4x
Px4x
MiCOM
H35
E01011
Px4x
DS Agile Ethernet
IEC 61850 ring network
under normal conditions
DS Agile Ethernet
IEC 61850 ring network
self healed
Figure 176: IED, bay computer and Ethernet switch with self healing ring facilities
A Self
-Healing Management function (SHM) manages the ring.
Under healthy conditions, frames are sent on the main ring (primary fibre) in one direction, with short check frames
being sent every 5 μs in the opposite direction on the back-up ring (secondary fibre).
If the main ring breaks, the SHMs at either side of the break start the network self-healing. On one side of the
break, received messages are no longer sent to the main ring, but are sent to the back-up ring instead. On the
other side of the break, messages received on the back-up ring are sent to the main ring and communications are
re-established. This takes place in less than 1 ms and can be described as “bumpless”.
The principle of SHP is outlined in the figures below.
Switch
A B D
1 2 3
Switch
C
1 2 3
Switch
E
1 2 3
Hx5x IED C264 IED Hx5x
Primary Fibre
S
econdary Fibre
Tx (Ep)Rx (Ep)
Rx (Rs)Tx (Es)
V01013
Figure 177: Redundant Ethernet ring architecture with IED, bay computer and Ethernet switches
Chapter 17 - Communications P54A/B/C/E
354 P54xMED-TM-EN-1
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