Mar 2013
Electricity Transmission
Alternative Bus Bar Protection Solution
Mar 2013
National Grid Electricity System Operator
National Grid TO Innovation Team
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Innovation Funding Incentive
Gas Distribution Networks
A policy for single digital bus bar protection has been employed on the National Grid Transmission network since 2002 either as a replacement system (for duplicated high impedance schemes) and for all new build double bus bar substations. These systems have a distributed architecture with remote bay units (interfacing to the plant) for each protected circuit with ruggedized cross site fibre connections to a central processing unit. Where a substation has a centralised relay room (e.g. GIS) layout, the bay units are co-located in a suite of cubicles and connected with a network of fibre patch cords.

A number of systems and versions have been installed from National Grid's preferred protection suppliers and Alliances over the past 20 years and these have required additional support through contracted Post Delivery Support Agreements (PDSA) to provide field staff with the resources to manage faults and defects. A recent protection policy change also requires a second (hot standby) central processing unit to be deployed (with it own dedicated fibre connections) to better manage contingency issues for central processing unit failures.

The systems installed to date have proven to be generally reliable; however each system is bespoke to each supplier with a limited technical life, leading to issues with future substation extensions and potentially the need to consider equipment upgrades and early asset replacement of the complete system. This will have major issues on future system access to carry out this work across a complete substation.

Through work with CIGRE, contacts with other utilities and National Grid, United States, it has been found that an alternative centralised bus bar protection system may offer greater asset management benefits in the longer term, especially when managed and supported by well trained internal staff. This project is desk top evaluation of an alternative bus bar protection design and the interface and application on the UK Transmission system.

This project aims to deliver an evaluation and desk top design solution of an alternative digital bus bar solution architecture. This will help formulate a future technical and procurement strategy for bus bar protection, potentially leading to a pilot installation, evaluation and deployment as a replacement (or new) bus bar protection system.