East-West Interconnector, Co Meath and Flintshire

Doran Consulting were appointed to lead the Design Team by power and automation experts ABB, on this project which saw the construction of a 500 MW ±200 kV HVDC (‘high voltage direct current’) light transmission system, connecting the electrical grids of the Republic of Ireland and Britain as part of a €600m investment by the Republic of Ireland transmission system operator EirGrid.

ABB was awarded the overall contract and appointed Doran Consulting to design converter stations comprising of the converter building, control building, AC switchyards and ancillary buildings, including a Portan Building, spare transformer base, spare parts building, generator buildings and MV transformer buildings.

The station buildings are steel-framed structures with reinforced concrete fire wall enclosures constructed around each transformer area. The steelwork frame has been designed to suit the various equipment loadings and deflection limits. Careful detailing of the earthing requirements was essential for this ‘energised’ building. The form of the roof structure varies from roof rafters to fabricated trusses, depending on the spans and loading requirements. The maximum height to eaves in the Valve Hall is approximately 24m.

The AC switchyard design involved detailed foundation design for filters, surge arrestors, earth switches, circuit breakers and disconnectors. Numerous buried conduits were required to service the equipment and a closely spaced copper grid was required to meet the earthing requirement.

The Republic of Ireland site is located at Woodland, Co Meath and the mainland Britain site is located at Shotton in Flintshire, Wales. The ground conditions varied between the two sites, with traditional pad and strip foundations being adopted for the Irish site and piled foundations for the Welsh site. Close liaison with both Meath County Council and Flintshire County Council was necessary to complete the drainage design and meet with their requirements.

The East-West Interconnector is the largest voltage sourced conversion High Voltage Direct Current scheme currently in operation in the world today. It is approximately 260km in length and the underground and undersea link has the capacity to transport 500 megawatts of electricity which is enough energy to power approximately 300,000 homes.