ABB Relion® Protection and Control REX640 Fiber-optic communication link

The relay also supports IEC 61850 process bus concept by

sending and receiving sampled values of currents and voltages.

With this functionality the galvanic interpanel wiring can be

replaced with Ethernet communication. The analog values are

transferred as sampled values using the IEC 61850-9-2 LE

protocol. REX640 supports publishing of one and subscribing

of four sampled value streams. The intended application for

sampled values are current-based differential protection

functions or sharing the voltage values with the relays that have

voltage-based protection or supervision functions. The relay

can receive up to four sampled value streams and totally 16

measurements can be connected into the protection relay

application.

Relays with process bus based applications use IEEE 1588

edition 2 for high-accuracy time synchronization.

For redundant Ethernet communication in station bus, the relay

offers either two optical or two galvanic Ethernet network

interfaces. An optional third port with optical or galvanic

Ethernet network interface is also available. The relay also

provides an optional fiber-optic port for dedicated protection

communication which can be used for up to 50 km distances

depending on the selected fiber transceiver. The intended

teleprotection applications for this port are line differential and

line distance protection communication or binary signal

transfer. The optional third Ethernet interface provides

connectivity for any other Ethernet device to an IEC 61850

station bus inside a switchgear bay, for example connection of

a remote I/O. Ethernet network redundancy can be achieved

using the high-availability seamless redundancy (HSR) protocol

or the parallel redundancy protocol (PRP), or with a self-healing

ring using RSTP in the managed switches. Ethernet

redundancy can be applied to the Ethernet-based IEC 61850.

Modbus and DNP3 protocols.

The IEC 61850 standard specifies network redundancy which

improves the system availability for the substation

communication. The network redundancy is based on two

complementary protocols defined in the IEC 62439-3 standard:

PRP and HSR protocols. Both protocols are able to overcome a

failure of a link or switch with a zero switchover time. In both

protocols, each network node has two identical Ethernet ports

dedicated for one network connection.

The protocols rely on the duplication of all transmitted

information and provide a zero switchover time if the links or

switches fail, thus fulfilling all the stringent real-time

requirements of substation automation.

In PRP, each network node is attached to two independent

networks operated in parallel. The networks are completely

separated to ensure failure independence and can have

different topologies. As the networks operate in parallel, they

provide zero-time recovery and continuous checking of

redundancy to avoid failures.