Client: SP Energy Networks

Value: £2.4m

Contract: NEC3 Eng & Construction Contract, April 2013, Option B

Project Description:

Demolition works, concrete bases, footings, slabs, formwork, reinforcement, ducting works, precast concrete duct units (FP McCann) drainage, piling, steel handrails & palisade fencing, kerbs and sub-base & capping works.

The displacement and disconnection of large synchronous generation from the National Electricity Transmission system and the decommissioning of Hunterston Power Station will have a detrimental impact on the system strength at Hunterston Converter Station. This therefore will affect the power flow of the Western HVDC link and its capability to transfer bi-directional power between Scotland and England.

To maintain system strength after the closure of Hunterston Power Station, it is proposed to reconfigure the overhead line circuits between Hunterston East, Neilston and Devol Moor 400kV substations to create a second Hunterston East – Neilston 400kV circuit.

Works Included:

This will be achieved by carrying out the following works.

• Refurbish 10km (approx.) of currently de-energised overhead line between towers ZN63 and ZN93 (ex INKI – NEIL circuit). The existing quad conductor system shall be replaced with a twin Totara 400kV conductor system.
• Disconnect and de-energise approximately 3km of the 400kV double circuit ZF route (ZF123 to ZF131).
• The existing 400kV cables at Marshall Moor compound shall be removed whilst the OHL connections shall be reconfigured by installing a new double circuit terminal tower.
• A new single circuit terminal tower including its span and downleads shall be installed at Neilston 400kV substation.
• Neilston 400kV substation layout reconfigured to a single switch arrangement. This will consist of new 400kV circuit-breakers, rotating centre post disconnectors with/without earthing switches, current transformers, capacitive voltage transformers, surge arresters, free standing earthing switch and post insulators. Some of the existing equipment installed in the 400kV compound shall be reused. This shall include 400kV earthing switch, surge arresters, post insulators, capacitive voltage transformers and current transformers.
• Reuse the strategic spare 1000MVA 400/275kV auto transformer at Neilston substation which is currently stored at Windyhill. The existing cooler banks including marshalling kiosk, multicore cabling etc. shall be replaced as detailed in the Level 6 Condition Assessment report carried out by Polaris Diagnostics and Engineering limited in April 2019.
• Create a new 275kV mesh corner at Neilson substation. This shall include new 275kV circuit breaker, rotating centre post disconnectors with earthing switches, current transformers and post insulators.
• A new set of 275kV cables shall be installed between sealing ends located in the 400kV and 275kV compounds to connect the 275kV side of the new 1000MVA transformer to the new 275kV mesh corner.
• Civil and structural works shall include new foundations, bund(s), plinth(s), support structures, construction of new and/or modification of the existing trenches, replacing any damaged trench covers (where applicable) and reinstatement of the ground. This shall also include demolition and removal of concrete gantries incl. its foundations, post insulators, busbars and over sail conductors including connectors/strain sets.
• All new equipment incl. its support structures shall be installed in a staged manner.

< Back to projects