Modelica‐AeroDyn: Development, benchmark, and application of a comprehensive object‐oriented tool for dynamic analysis of non‐conventional horizontal‐axis floating wind turbines

Abstract

AbstractThe exploitation of offshore wind energy by means of floating wind turbines is gaining traction as a suitable option to produce sustainable energy. Multi‐rotor floating wind turbines have been proposed as an appealing option to reduce the costs associated with manufacturing, logistics, offshore installations, and operation and maintenance of large wind turbine components. The development of such systems is forestalled by the lack of a dedicated tool for dynamics and load analysis. Standard codes, such as FAST by NREL, offer the desired fidelity level but are not able to accommodate multi‐rotor configurations. A few experimental codes have been also proposed, which may accommodate multi‐rotor systems, but low flexibility makes them impractical to study a vast range of innovative multi‐rotor FWTs concepts. To close the gap, this work presents the development and comprehensive benchmark of a fully coupled aero‐hydro‐servo‐elastic tool able to easily accommodate arbitrary platform and tower geometries and the number of wind turbines employed. Development is carried out in Modelica, which allows for the employment of the same code functionality in a virtually unlimited number of physical configurations. Full blade‐element momentum capabilities are achieved by integrating into Modelica the well‐established NREL aerodynamic module AeroDyn v15 within FAST v8. Structural dynamics of tower and blades are implemented through a lumped‐element approach. Hydrodynamic loads are computed by employing the DNV software SESAM WADAM. Thorough benchmark is performed against FAST, and positive results are obtained. The dynamic performance of a two‐rotor floating wind turbine is finally assessed considering different turbulence spectrums.