BritNed

BritNed is a high-voltage direct current (HVDC) submarine power cable interconnector between the United Kingdom and the Netherlands. This 1,000 MW capacity link connects the Isle of Grain in Kent, UK, to Maasvlakte in Rotterdam, Netherlands, spanning 260 km across the North Sea.

Project Overview

The BritNed project was announced in May 2007 and began operation on April 1, 2011. It is a joint venture between National Grid plc (UK) and TenneT (Netherlands), operating independently from their regulated businesses. The total cost of the project was approximately €600 million, completed on time and within budget.

Technical Specifications

BritNed utilizes a bi-pole 450 kV interconnector consisting of two bundled HVDC cables. The system employs HVDC technology to efficiently transport electricity with a loss factor of only 3%. This means that when 1030 MW is transmitted from Great Britain, 1000 MW arrives in the Netherlands.

Converter Stations

Two converter stations are located at each end of the cable link. These stations are essential for converting between AC and DC, as the electricity networks in both countries operate on AC. The Isle of Grain converter station serves as the primary site for daily operations monitoring.

Transformers

Each site houses six transformers, with three for each of the two 500 MW poles. These massive structures weigh 282 tonnes each and measure approximately 10m x 4m x 5m.

Valve Halls

The conversion between AC and DC occurs in the valve halls, which contain 1200 thyristors (solid-state valves) for this purpose.

Subsea Cables

Two HVDC cables, one for each pole, connect the converter stations. These cables are buried up to 3m below the seafloor for protection. Each meter of cable weighs 44kg, with a total combined weight of approximately 23,000 tonnes for both cables.

Project Significance

BritNed plays a crucial role in enhancing the European energy market by facilitating electricity trading between the UK and Netherlands, improving security and diversity of electricity supplies in both countries, enhancing competition in the northwestern European energy market, and contributing to the development of the European super grid project.

Market Operations

BritNed enables over 70 participating organizations to trade power between the British and Dutch markets. The interconnector's capacity is allocated through various auction mechanisms, including long-term, day-ahead, and intraday auctions. This allocation process ensures transparency and open access for all market participants.

Environmental Considerations

The project underwent thorough environmental analysis, including biodiversity assessments, and received approvals from both British and Dutch authorities. The cable route was carefully chosen to minimize environmental impact.

Challenges and Outages

BritNed has faced some operational challenges, notably experiencing several outages due to undersea cable faults in 2020 and 2021. A significant outage occurred on March 9, 2021, with restoration delayed until June 7, 2021.