The transmission system operator TenneT has already reconnected the DolWin2 offshore grid connection, which has been disconnected since 07 November 2016, on 07 January 2017. Since then, the offshore wind farms it connected were able to transfer power back to shore. This meant that reconnection took place more than 11 weeks earlier than the expected date of 27 March 2017. This significant reduction in switch-off time was made possible thanks to tremendous efforts on the part of all participating companies as well as the involvement of the involved landowners and authorities. The dry weather during the months of November and December, which was very unusual for the time of year, was also a decisive factor in the rapid progression of work.
Essential for this acceleration was the close and constructive cooperation between TenneT and ABB, the general contractor commissioned for this project. These include, among others, the establishment of additional resources and the optimisation of the efficiency of repair work in the field of cable routes. This interaction enabled a decisive time optimisation of the repair process. The result was that DolWin2, and therefore also the connected offshore wind farms, were reconnected to the grid considerably earlier than initially assumed.
During the test phase, a DolWin2 cable component failed repeatedly. In June 2016, TenneT took the decision to temporarily take the system offline and requested ABB to remedy the defects. This work was immediately started at full speed. The preparations for the acceptance process can now be continued after the successful conclusion of this rectification work. By means of this, TenneT was able to fulfil responsibility as a transmission system operator to ensure there are no problems later on during grid operations and that subsequent charges for electricity consumers are avoided to the greatest possible extent. In this regard, TenneT will also consistently carry on working to keep the possible burden on electricity customers as small as possible. TenneT fully relies on ABB, the general contractor for this project, to ensure that the DolWin2 offshore grid connection is brought up to acceptance condition.
Facts and figures regarding DolWin2
- 135 kilometre-long cable in high voltage direct current transmission technology (HVDC) with a maximum transmission capacity of 916 megawatts
- 90 kilometres of land cable, 45 kilometres of subsea cable
- Grid connection point: Dörpen-West