Ethernet Redundancy - ABB Relion SMU615 Technical Manual

Section 2
SMU615 overview
2.5.1
24

Ethernet redundancy

IEC 61850 specifies a network redundancy scheme that improves the system
availability for substation communication. It is based on two complementary
protocols defined in the IEC 62439-3:2012 standard: parallel redundancy protocol
PRP-1 and high-availability seamless redundancy HSR protocol. Both protocols rely
on the duplication of all transmitted information via two Ethernet ports for one logical
network connection. Therefore, both are able to overcome the failure of a link or
switch with a zero-switchover time, thus fulfilling the stringent real-time
requirements for the substation automation horizontal communication and time
synchronization.
PRP specifies that each device is connected in parallel to two local area networks.
HSR applies the PRP principle to rings and to the rings of rings to achieve cost-
effective redundancy. Thus, each device incorporates a switch element that forwards
frames from port to port.
IEC 62439-3:2012 cancels and replaces the first edition published in
2010. These standard versions are also referred to as IEC 62439-3
Edition 1 and IEC 62439-3 Edition 2. The merging unit supports IEC
62439-3:2012 and it is not compatible with IEC 62439-3:2010.
PRP
Each PRP node, called a doubly attached node with PRP (DAN), is attached to two
independent LANs operated in parallel. These parallel networks in PRP are called
LAN A and LAN B. The networks are completely separated to ensure failure
independence, and they can have different topologies. Both networks operate in
parallel, thus providing zero-time recovery and continuous checking of redundancy to
avoid communication failures. Non-PRP nodes, called single attached nodes (SANs),
are either attached to one network only (and can therefore communicate only with
DANs and SANs attached to the same network), or are attached through a redundancy
box, a device that behaves like a DAN.
1MRS758407 B
SMU615
Technical Manual