Danish transmission systems operator Energinet.dk has invited tenders for a marine warranty surveyor for its Kriegers Flak AC and Combined Grid Solution (CGS) projects.
Energinet.dk wants to purchase marine warranty services to ensure that marine operations carried out by sub-contractors are performed in a sound and good manner in accordance with good practice and international standards such as DNV-GL Noble Denton and DNV standards.
The contract is valued at EUR 500,000, and the tender will remain open until 11 August 2016.
The procurement documents are available for unrestricted and full direct access, free of charge, here.
The Kriegers Flak AC and CGS projects comprise three topsides and two gravity based substructures to be installed in the Danish waters of the Baltic Sea. The topside and gravity based substructure fabrication site is located in northern Europe. Hollandia Offshore and Energinet.dk signed a contract for the engineering, procurement and commissioning of the Kriegers Flak substations on 31 May.
The Kriegers Flak CGS is a joint venture project between Energinet.dk and the German TSO, 50Hertz Transmission.
The project, which holds the status of a “project of common interest” (PCI) given by the European Commission, aims to establish the world’s first offshore interconnection by using the national grid connections to offshore wind farms in the Baltic Sea.
The Kriegers Flak CGS will connect the Danish region of Sjaelland and German Mecklenburg-Western Pomerania. It should have a capacity of 400 megawatts (MW).
Germany already has two offshore wind farms in the area, the 48MW Baltic 1 and the 288MW Baltic 2, while Denmark is currently preparing to erect the 600MW Kriegers Flak. Kriegers Flak and Baltic 2 are located less than 30 kilometres away from each other and will be connected by two submarine cables to establish the interconnector.
As eastern Denmark and Germany are two different synchronous areas, a frequency transformation is necessary. This will be done by two voltage source converters (VSC) that convert the alternating current (AC) from the Nordic synchronous area into direct current (DC) and directly back to AC, now adapted to the European synchronous area.
The so-called back-to-back converter will be installed in Bentwisch near Rostock, Germany.
Due to the different voltage levels of the Danish and German offshore wind farms, an offshore transformer (150 to 220 kV) is required which will be placed on an additional offshore platform located in the vicinity of one of the Danish offshore platforms.
The project partners expect construction to begin in late 2016 or early 2017. Operation is planned to start by the end of 2018.