Situation

NEMO Link, a joint venture between National Grid and Belgian transmission system operator Elia, is the UK’s first subsea electricity interconnector to Belgium, capable of transmitting up to 1,000 MW (1GW) at 400 kV for an annual transmission capacity of 8.76 TWh, enough to serve 500,000 homes. NEMO Link plays a key role in delivering cleaner energy to UK consumers, while also making supplies more secure and competitive.

Due to discrepancies between the UK and European electricity networks the interconnector has AC/DC – DC/AC bi-conducting rectification equipment to provide synchronisation.

The interconnector stations at Richborough Kent and Zeebrugge Belgium are mirror images of each other. These interconnectors stations are extremely complex and the specialist high power electronic conversion equipment generates substantial waste heat.

Installation of the 130kM of the subsea HVDC cross-linked polyethylene (XLPE) cable system

Task

Working closely with Murphy Construction, IESworks were to deliver a turnkey solution of LV switchgear, bespoke control equipment and software programming of an integrated control system for specialist HVAC equipment within the converter and reactor halls.

The physical layout and varying equipment sizes of the 1000 MW inverters and ancillary equipment created a large and complex heat profile to control, balance and dissipate. With such high power equipment, effective control of water condensation was a key safety function of the system.

Action

IESworks collaborated extensively with all the key design stakeholders to understand the functional requirements and ensure a successful solution. Complex software programming of control algorithms and HVAC models were used to calculate and balance the heat profiles. IESwork had to ensure that the design components met the particular safety requirements of the entire system.

Detailed research was carried out by IESworks, concluding the most effective solution required Siemens control system components. This research included calculations for the overall reliability of individual component mean time to failure (MTTF) rates into a final performance value that exceeded the reliability requirements of the project. The uncertainty of the prolonged effect of the challenging environment required careful selection of components within the technical design.

NEMO LINK Link cross channel route (Note: due to security restrictions IESworks cannot display actual images of the station or provide information on products used.)

Result

IESworks designed, manufactured, programmed, installed and commissioned a LV electrical distribution system and an integrated HVAC control system as a turnkey solution to meet European Functional Safety standards IEC 61508 (SIL) and Performance Level Standard EN ISO 13849-1. IESworks integrated the HVAC control system with the station C&P master controller, supplied by Siemens GMBH in Germany.

A detailed project plan ensured all information and manufacturing proceeded on a scheduled basis and helped identify milestones and key dates within the project lifecycle. This project was delivered safely, on time and in budget to specification with regulatory compliance all client specified performance requirements . IESworks are proud to have been part of the construction team to have delivered Nemo Link Link ahead of schedule and under budget.

https://www.nationalgrid.com/nemo-link-open-business

A further order has since been received for the Eleclink Interconnector at Folkestone.