IEC 61850 and Ethernet redundancy

Communication services in the substation

– IEC 61850-8-1 part allows the elimination of copper wires between relays on a horizontal level, i.e. relay-to-relay communication – substation bus;

IEC 61850-9-2LE allows the sharing of digitised information from transformers or sensors with other relays in a standardised way – process bus.

These services are categorised as client-server services:

– The MMS traffic, defined in IEC 61850-8-1. allows MMS clients such as SCADA, OPC servers or gateways to access all IED objects “vertically”.

This traffic flows on the station bus and the process bus.

Real-time services:

– The GOOSE flow, as defined in IEC 61850-8-1. which allows the IED to exchange data “horizontally” between machine rooms, or “vertically” between the process level and the machine room level.

In particular, status signals and trip signals are usually also used for interlocking. These information flows are usually transmitted via the station bus and/or the process bus.

– The SV (Sampled Value) flow is defined in IEC 61850-9-2 and is used to transmit voltage and current samples.

This flow is usually on the process bus, dcs-sis.com but can also flow via the station bus, e.g. for busbar protection, centralised protection and control, and phase measurement.

Generic Object-Oriented System Events (GOOSE)

– Standardised horizontal communication

– Replaces hard wiring between relays and controllers

– GOOSE is used to broadcast events between relays in a substation.

– The GOOSE communication link between relays is monitored and controlled by cyclically sending data.

– Ethernet technology provides a fast and reliable station bus for data transfer.