scope:

General

Global performance analyses determine the global effects of environmental conditions and other loads on the Floating Offshore Wind Turbine (FOWT) and its components including the tower, hull structure, mooring lines or tendons, anchors, export electrical cable, etc. Global performance analyses should be carried out for all critical conditions in the pre-service and in-service phases, represented by the design load conditions specified in Chapter 5, Section 2 of the ABS Guide for Building and Classing Floating Offshore Wind Turbine Installations (FOWTI Guide).

Because significant interactions could occur among the Rotor-Nacelle Assembly (RNA) and control system, the floating support structure and the stationkeeping system, an integrated ('coupled') model including all these components is recommended to be used for global performance analyses. An alternative method, where the dynamic analyses of the stationkeeping system are performed separately by using the responses of the floating support structure as boundary conditions, may also be acceptable, provided that the coupling effect of the stationkeeping system and the floating support structure is adequately taken into account.

The global performance analysis software should have the capability of considering complex interactions among aerodynamic loads, hydrodynamic loads, actions of turbine safety and control systems and structural dynamic responses of the FOWT. The analysis procedures should reflect the application limits of the selected software. Both publically available, industry-recognized software and in-house software may be used for the analyses. However, in-house software has to be adequately calibrated against model tests, field tests or the industry-recognized software.

General guidance on global performance analyses of the floating support structure and the stationkeeping systems can be found in:

• ABS Rules for Building and Classing Floating Production Installations (FPI Rules), API RP 2T, API RP 2FPS and ISO 19904-1 for the design of floating offshore structures API RP 2SK, API RP 2SM and ISO 19901-7 for catenary mooring and taut leg mooring systems.

• API RP 2T for TLP tendon systems. References are also made to other appropriate ABS Rules, Guides and Guidance Notes such as those listed in Subsection 1/7.