DNV GL Recommends Practice for Offshore HVDC Systems

New DNV GL guidelines and practices ensure safe connection of offshore wind to the transmission grid using High Voltage DC technology.

DNV GL has together with the Swedish Transmission Research Institute (STRI) and ten industry players developed a methodology for technology qualification of offshore High Voltage Direct Current (HVDC) technologies through a joint industry project.

As offshore wind farms are being built farther from the coast and more offshore oil and gas installations are powered from shore, there will be an increasing need for long-distance underwater power transmission in the years to come. Use of HVDC transmission allows power transmission through cables over longer distances and higher capacities compared to what is feasible when using AC transmission, and will hence often be the preferred solution for long-distance power underwater transmission. However, to date operational experiences with offshore HVDC transmission technologies are very limited and there is a lack of relevant standards, guidelines and recommendations for stakeholders to rely on.

Peter Vaessen, Segment Director Future Transmission Grids at DNV GL comments: “Implementation of new technology always introduces uncertainties that imply risk for its developers, manufacturers and end-users. With this technology qualification, we enable our customers to provide the evidence that the technology used will function within the specified limits with an acceptable level of confidence. Customers can ensure that each step is agreed in advance with the technology provider and the buyer, whilst delivering projects on time.”

The immature nature of offshore HVDC technologies causes uncertainties and increased risk exposure for stakeholders and makes the projects complicated and costly. As a means to manage the technology risks associated with offshore HVDC transmission projects, DNV GL and STRI have developed a recommended practice on technology qualification of offshore HVDC technologies through a joint industry project with ten industry players.

The new recommended practice is based on DNV GL’s methodology for technology qualification, which has been used extensively for managing technology risks in the oil and gas industry for more than a decade.

Technology qualification is a method for providing evidence that technical equipment will function within specified operational limits with an acceptable level of confidence, both for suppliers and buyers of the relevant equipment. In order to accurately incorporate feedback from all major stakeholders during the testing process, this Joint Industry Project partnered with major industry players including: ABB, Alstom Grid, DONG Energy, Elia, Europacable, Scottish Power, Statkraft, Statnett, Statoil, Svenska Kraftnät and Vattenfall.

With several distinguishing features, a DNV GL recommended practice is more than just a guideline. It is the result of a collaborative effort of an industry-wide consortium. Like all of the 100+ recommended practices DNV GL manages, the recommended practice on technology qualification of HVDC technologies will be extensively peer reviewed, professionally formulated and published, and regularly updated.

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