Structural health and prognostics management for offshore wind turbines :

Abstract

Operations and maintenance costs for offshore wind plants are expected to be significantly higher than the current costs for onshore plants. One way in which these costs may be able to be reduced is through the use of a structural health and prognostic management system as part of a condition based maintenance paradigm with smart load management. To facilitate the creation of such a system a multiscale modeling approach has been developed to identify how the underlying physics of the system are affected by the presence of damage and how these changes manifest themselves in the operational response of a full turbine. The developed methodology was used to investigate the effects of a candidate blade damage feature, a trailing edge disbond, on a 5-MW offshore wind turbine and the measurements that demonstrated the highest sensitivity to the damage were the local pitching moments around the disbond. The multiscale method demonstrated that these changes were caused by a local decrease in the blade's torsional stiffness due to the disbond, which also resulted in changes in the blade's local strain field. Full turbine simulations were also used to demonstrate that derating the turbine power by as little as 5% could extend the fatigue life of a blade by as much as a factor of 3. The integration of the health monitoring information, conceptual repair cost versus damage size information, and this load management methodology provides an initial roadmap for reducing operations and maintenance costs for offshore wind farms while increasing turbine availability and overall profit.

Aerodynamic Sensitivity Analysis of Rotor Imbalance and Shear Web Disbond Detection Strategies for Offshore Structural Health Prognostics Management of Wind Turbine Blades

“…Intermediate airfoil shapes were developed that preserve the blending of camber lines as well as a smooth blade thickness profile. Figure 1 shows the finite element model of the blade developed at Sandia 12 in ANSYS with the colored sections representing different composite materials. This high degree-of-freedom model was translated into a model consisting of several beam elements using Sandia's Blade Property Extraction tool (BPE) 22 .…”

Structural health and prognostics management for the enhancement of offshore wind turbine operations and maintenance strategies

“…In this paper, an initial development and integration of SHPM into the O&M process for offshore wind power plants are addressed in several ways. First, relevant damage cases are identified for simulation.…”

Wind turbine blade shear web disbond detection using rotor blade operational sensing and data analysis

“…Basic specifications of the model are listed in table 1. A new blade model was developed in Sandia's Numerical Manufacturing and Design (NuMAD) tool to be used with the NREL 5 MW turbine model, which is the same model used in the initial studies [16]. A detailed blade model did not exist and was needed so that damage could be introduced into the blade structure within the multi-scale modelling and simulation framework (as described above).…”

“…In the area of the blade in which the shear web disbond existed, the constraints were removed so that there was no connection between the top of the blade and the shear web. A similar approach was used by Griffith et al [16] to simulate a trailing edge disbond on the same blade model. While this modelling disbond methodology is effective in modelling a disbond in which the blade and shear web do not come into contact, it fails to take into account the possible interaction of the top and bottom surfaces of the disbond.…”