The offshore grid connection BorWin3 in the German Bight near the island of Borkum has been operational since August 2019. The twelfth offshore grid connection project of TSCNET shareholder TenneT, the Dutch-German transmission system operator (TSO), extends TenneT’s transmission capacity for offshore wind farms in the German North Sea by a further 900MW, so that the total capacity already amounts to 7.132GW – and since the German government’s expansion targets for wind energy in the North Sea by 2020 are only 6.5GW, the TSO has clearly exceeded them.
After several weeks of trial operation, BorWin3 has now been handed over to TenneT by the general contractors. The consortium of Siemens and Petrofac was responsible for the construction, transport, installation and commissioning of the two BorWin3 converters (offshore and onshore). The transfer of operations represents a further major contribution to the energy transition in Germany and Europe.
At the same time, TenneT is pursuing ambitious goals for its Dutch offshore projects. The TSO is planning on a large scale, as the Dutch government has set a target in its “Offshore Wind Roadmap 2030” to reach a cumulative offshore wind capacity of 11.5GW by 2030, so that 40% of the Dutch electricity demand will then come from offshore wind farms. In the IJmuiden Ver wind energy area, off the coast of the region of North Holland, the company intends to implement two 2GW offshore grid connections to complement the eight 0.7GW AC grid connections already planned in the Dutch North Sea. As there is currently no 2GW grid connection, a new platform design and a high-voltage direct current (HVDC) transmission system that enables increased power transmission are required.
Furthermore, given the long distance to the coast and the size of the IJmuiden Ver wind energy area, a 2GW HVDC solution based on 525kV seems to be the most economically solution. It requires only one cable system per 2GW, which limits the impact on the environment and surroundings. The technology is by no means fundamentally new to TenneT. The TSO can draw on its extensive HVDC experience with offshore grid connections in Germany and with interconnectors. TenneT also uses the 525kV level for NordLink, the new offshore connection between Germany and Norway.
To implement such an innovative DC system, TenneT has initiated the design phase with five HVDC suppliers based on an innovation partnership. These suppliers will develop the advanced 2GW-525kV HVDC solution based on the criteria defined by the company and the technical capabilities of the partners.