National Grid Electricity System Operator
National Grid TO Innovation Team
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Live Line working was initially introduced in the 1960s and actively utilised in the
1990s on the Overhead Lines (OHL). The project will enable National Grid use to use
innovative techniques to deliver benefits to the system operator. These benefits
are primarily around minimising system outages to carry out work and reducing
system operator costs. The transmission system is likely to become
increasingly constrained over the next 5-10 years, based on forecast constraint
costs, new access arrangements, continued asset investment requirements and
new generation connections. Live Working in substations offers significant
opportunities in enabling certain maintenance and defect work to be carried out
against this background, however to provide assurance that the long term
investment and commitment is workable on the existing network, a more in depth
assessment of the substations is required in order to establish the criteria for live
working can be met. This assessment would be undertaken by the French
Electricity Company RTE who are one of the worlds experts on live working at
High Voltage (HV).
The re-establishment of Live Line Working on OHLs within National Grid has
already been approved by governance groups within National Grid and
discussions with Ofgem on this matter have already taken place. Substation
live working is the next logical step to undertake.
Historically the HV equipment maintenance work in substations has been
undertaken on circuits which have been de-energised, isolated and earthed. This
requires longer return to service times of circuits and limited access availability.
Because of the way the network is being developed and enhanced to facilitate
the build of new generation and asset replacement etc it will become
increasingly more constrained and hence even more difficult to get system
access for essential maintenance and defect repairs.
To fully undertake live working in substations, further investment in staff training
and specialist equipment is required and hence, to justify this investment, the
existing substations will need to be assessed to see if the configurations used
will be compatible with the established criteria for live working.