East West Interconnector

At the time of commissioning, it was the largest voltage source converter (VSC) scheme in operation in the world, carrying enough energy to power 300,000 homes over a length of 164 miles (264 kilometers).

Acting on behalf of EirGrid, we were the employer’s representative on this landmark 500MW high voltage direct current (HVDC) scheme. The interconnector represents a significant portion of the energy infrastructure of the Irish transmission system, enabling cross-border electricity flows between Ireland and Britain, and enhancing grid reliability and security of supply. 

The scheme comprises a number of key elements: two 400kV connection points into the existing AC networks; converter stations in each country and ±200kV XLPE DC cables from the converter stations to the coast and then 116 miles (187 kilometers) across the Irish Sea. For the extensive marine portion of the works, we collaborated with a marine environmental design and risk management specialist.

As employer’s representative, we were engaged at an early stage of the project and provided support for: site selection, permitting, stakeholder management, preparation of the technical specification, tender evaluation, design review, project and programme management, health and safety coordination, test witnessing, quality inspections during construction, commissioning support, demonstration of grid code compliance and review of operations and maintenance documentation.

Since going into commercial operation, the interconnector has increased security of supply and competition in the Irish electricity market.