ABB energises final outgoing circuit as NEDL’s new 132kV GIS Norton project nears completion
2005-11-30 - The new 132kV Norton substation is not only one of the first to be constructed by a customer DNO (Distribution Network Operator) under new regulations, it is also probably the largest and most strategically important project ever undertaken by NEDL.
ABB has successfully energised and transferred to National Grid the 14th and final outgoing circuit at NEDL’s new indoor GIS (gas insulated switchgear) 132kV substation at Norton, near Stockton on Tees, with the major works completed in just over two years since first breaking ground on the £9 million project in April 2003. ABB is now completing the work by demolishing the old AIS (air insulated switchgear) substation to create the space for the next phase, the construction of a new 11kV substation.
Norton 132 kV substation serves a population of over 250,000 - a significant part of the NEDL (Northern Electric Distribution) load base - so secure and reliable operation of the site is of vital importance. The overall site is actually home to four substations ranging from NGT’s 400kV and 275kV substations to NEDL’s 132kV and 11kV local distribution network.
The ABB project has focused on the 132kV substation, which interconnects the National Grid and NEDL’s distribution network. The existing AIS (Air Insulated Switchgear) substation was built in the late 1930s and had reached the end of its economical working life. Previously, National Grid would have been responsible for building and project managing the replacement. However, a recent relaxation of regulations now allows a customer DNO such as NEDL to build a substation and have the relevant circuits transferred to National Grid on completion.
NEDL’s original plan was to carry out a ‘like for like’ replacement and it was put out to tender as a turn-key project on this basis. However, ABB then provided an alternative bid, based on its compact ELK-04 GIS (gas insulated switchgear) technology, at around the same cost as a new AIS substation.
The main advantage of the GIS approach is that it has enabled the joint NEDL/ABB team to work with a ‘brown field’ site, with the main construction and installation of switchgear completed off-line and the circuits switched-in in a controlled way, so that outages could be planned well in advance. In comparison, the AIS approach would have involved the greater risk of working in a live compound and direction of outages would have been much more challenging.
A further benefit of the GIS approach is that the new substation is housed indoors, in a purpose built building occupying around one sixth of the space occupied by the existing AIS substation. In the long-term this will significantly improve the aesthetics of the site as the AIS substation can now be demolished, and the indoor substation also requires less maintenance as well as offering greater reliability.
The new 132kv substation, rated at 540MVA, features 20 bays of switchgear (four of which have been transferred to National Grid) with four incoming circuits fed by Supergrid transformers and 14 outgoing circuits, two of which feed local grid transformers.
Ray Puryer, NEDL’s project engineer, said: 'This has been probably the largest and most strategically important project ever undertaken by NEDL. And the key to the success of this mammoth task has been in ABB and NEDL’s thorough approach to planning, coordination and attention to detail at every phase, from initial design, through civil works to installation of the equipment and commissioning. The team has been particularly strong, especially in the way that every party involved has been encouraged to work together right from the very first site meeting. It has been refreshing to see the traditional customer-supplier relationship evolve into a true partnership between ABB and NEDL based on mutual support and flexibility. National Grid has also played a very important role by taking an equally flexible approach to its own requirements and offering help and assistance as required.'
In addition to this contract, NEDL has also asked ABB to replace two of the grid transformers and to construct a new 11kV substation in the space created by the 132kV GIS project. So by 2006 ABB will have revamped a significant part of the whole Norton site.