Fibre Optic Based Substation Communications
Electricity North West Limited
Electricity North West Innovation Team
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Innovation Funding Incentive
Comms & IT
The project is a trial of new technology numeric line current differential relays using
digital communications over ENWLs SDH fibre network.
To trial the relays using a number of different communications configurations and
paths. This will inform on the use of such relays over the SDH network and the actual communications requirements. The trial included direct fibre, multiplexed fibre and mixed fibre/copper communications paths.
To ensure that the relays trialled using digital communications operate correctly for in zone and are stable for out of zone faults. (The circuits chosen have poor fault history and are associated with other circuits with poor fault history)
To ensure that with an ageing population of traditional relays and pilot cables, there will be an option that provides a completely new system of unit protection not relying
on unsupervised copper pilot cables.
At 132kV, protection commonly uses rented BT circuits. This is used for line current
differential, distance protection and inter-tripping. Experience gained in the trial will
assist in the migration of these functions to the ENWL fibre network. This is particularly
important as it is becoming apparent that the BT 21st Century Network project may
have an adverse effect on some protection schemes