A digital twin solution for floating offshore wind turbines validated using a full-scale prototype

Abstract

Abstract. In this work, we implement, verify, and validate a physics-based digital twin solution applied to a floating offshore wind turbine. The digital twin is validated using measurement data from the full-scale TetraSpar prototype. We focus on the estimation of the aerodynamic loads, wind speed, and section loads along the tower, with the aim of estimating the fatigue lifetime of the tower. Our digital twin solution integrates (1) a Kalman filter to estimate the structural states based on a linear model of the structure and measurements from the turbine, (2) an aerodynamic estimator, and (3) a physics-based virtual sensing procedure to obtain the loads along the tower. The digital twin relies on a set of measurements that are expected to be available on any existing wind turbine (power, pitch, rotor speed, and tower acceleration) and motion sensors that are likely to be standard measurements for a floating platform (inclinometers and GPS sensors). We explore two different pathways to obtain physics-based models: a suite of dedicated Python tools implemented as part of this work and the OpenFAST linearization feature. In our final version of the digital twin, we use components from both approaches. We perform different numerical experiments to verify the individual models of the digital twin. In this simulation realm, we obtain estimated damage equivalent loads of the tower fore–aft bending moment with an accuracy of approximately 5 % to 10 %. When comparing the digital twin estimations with the measurements from the TetraSpar prototype, the errors increased to 10 %–15 % on average. Overall, the accuracy of the results is promising and demonstrates the possibility of using digital twin solutions to estimate fatigue loads on floating offshore wind turbines. A natural continuation of this work would be to implement the monitoring and diagnostics aspect of the digital twin to inform operation and maintenance decisions. The digital twin solution is provided with examples as part of an open-source repository.

Enhancing Reliability in Floating Offshore Wind Turbines through Digital Twin Technology: A Comprehensive Review

“…Offshore wind turbine structures represent a pioneering frontier in renewable energy, harnessing the power of wind over vast expanses of the ocean to generate clean and sustainable electricity [8,10,11,14,15,18,21]. These structures, typically consisting of towering masts anchored to the seabed, support massive turbine blades that capture wind energy and convert it into electricity through rotational motion.…”

“…Engineering applications of semi-submersible platforms include the WindFloat platforms by Principle Power, Saitec's SATH (Swinging Around Twin Hull) platforms, BW Ideol's Damping Pool floating foundation, the OC4-DeepCwind platform, and the W2Power Platform [39]. In addition to the semi-submersible platform, Spar and tension leg platforms (TLP) are also used in offshore wind projects [4,11,18].…”

“…In the examination of the aforementioned 5 MW NREL virtual wind turbine [81], wind and ambient profiles were imported from supervisory control and data acquisition (SCADA) data. Subsequently, the loading profile was integrated into FAST (now OpenFAST) [11,12] or similar aero-elastic-servo-control models to generate inputs (e.g., torque and speed) for the generator. Within the DT framework, virtual sensors were generated for structural locations without strain gauges, utilising a blend of aeroelastic models and finite element methods (FEM).…”

“…Energies 2024, 17,1964 2 of 23 The expansive oceanic expanse presents favourable conditions for the development of large-scale wind farms and turbines [7,8]. Offshore wind power benefits from faster wind speeds, greater uniformity, and extended operational availability compared to onshore counterparts [9][10][11][12]. While the upper tower components of an offshore wind turbine (OWT) resemble their onshore counterparts, the primary distinction lies in the design of the lower platforms [8,13].…”

Digital Twin-Based Approach for a Multi-Objective Optimal Design of Wind Turbine Gearboxes

“…The work referred to in [38] developed a DT virtual sensor for online load monitoring and subsequent RUL assessment of WT gearbox bearings, which makes use of a SCADA system with a physics-based gearbox model. The work referred to in [39] implemented, verified, and validated a physics-based DT and applied it to a floating offshore WT to estimate the aerodynamic loads, wind speed, and section loads along the tower for estimating the fatigue lifetime of the tower.…”