DNV DNV-SE-0422 PDF

This service specification describes the certification of floating wind turbines considering the complete lifecycle. It includes concept, basic design, project, in-service, prototype and type certification for floating wind turbines, floating wind farms and related components, e.g. hull, mooring lines, ballast system. In addition, it includes prototype certification intended for demonstrators, type certification intended for subsystems and components of a floating wind turbine manufactured in series, and guidance for certification of dynamic power cables. Further, this document specifies the DNV deliverables and the validity of these.

Figure 1-1 shows the certification phases during the lifecycle of a floating wind turbine (development, construction, operation and maintenance). The certification phases are applicable both for a prototype (demonstrator) or for several units of a floating wind farm. For further certification phases like certification of lifetime extension, decommissioning, repowering, see DNV-SE-0190.

Below follows a high-level description of the different certification levels covered in this service specification.

— Concept certification: certification of an early phase design e.g. pre-front end engineering design (pre- FEED) , typically for generic conditions and under consideration of a generic rotor-nacelle assembly (RNA) or components.

Guidance note:

The early phase assessment of feasibility of floating structures may be called AIP (approval in principle).

— Basic design certification: certification of basic design of a floating wind turbine or components, e.g. front end engineering design (FEED), either for generic site conditions or a specific site. It is applied prior to a detailed design and should allow material order.

— Project certification: certification of the asset(s) floating wind turbine within a wind farm or a single installation at a dedicated site. For obtaining a project certificate, the phases design basis, design, fabrication surveillance, transport and installation surveillance and commissioning surveillance including operation and maintenance manuals are evaluated.

— In-service certification: certification of in-service of one or several wind turbines in a wind farm. Follow-up after project certification during operation including periodic on-site inspection.

— Prototype certification: certification of a single or up to five (5) floating wind turbines or their components for an operational period of maximum three (3) years to allow testing and demonstration of new designs. Prototype certification may also be recognized as a project certification with a reduced scope.

— Type certification: certification or approval of a component or subsystem of a floating wind turbine manufactured in series, either for generic conditions, an envelope of conditions or for a specific site.

DNV's scope of work depends on different aspects such as development stage, degree of novelty of design and uncertainties. This is described in Sec.2. The level of involvement by DNV for the different certification levels and project phases have been indicated in Table 1-2.