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

Abstract

Offshore wind turbines are an attractive source for clean and renewable energy for reasons including their proximity to population centers and higher capacity factors. One obstacle to the more widespread installation of offshore wind turbines in the USA, however, is that recent projections of offshore operations and maintenance costs vary from two to five times the land-based costs. One way in which these costs could be reduced is through use of a structural health and prognostics management (SHPM) system as part of a condition-based maintenance paradigm with smart loads management. This paper contributes to the development of such strategies by developing an initial roadmap for SHPM, with application to the blades. One of the key elements of the approach is a multiscale simulation approach 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. A case study of a trailing edge disbond is analysed to demonstrate the multiscale sensitivity of damage approach and to show the potential life extension and increased energy capture that can be achieved using simple changes in the overall turbine control and loads management strategy. The integration of health monitoring information, economic considerations such as repair costs versus state of health, and a smart loads management methodology provides an initial roadmap for reducing operations and maintenance costs for offshore wind farms while increasing turbine availability and overall profit.

Effects of power reserve control on wind turbine structural loading

“…De-rating tends to reduce the fatigue loads of all components. This is not an unexpected result, as de-rating has been described in the literature as a method for reducing fatigue loads at the expense of power capture (Griffith et al 45 ). Additionally, all controllers are shown to reduce the loads of blade-root-flap bending and tower-base fore-aft bending.…”

Failure Mode Identification and End of Life Scenarios of Offshore Wind Turbines: A Review

“…According to [60], the cost of offshore O&M activities currently varies from two to five times the cost onshore. One of the reasons might be the additional effort that is being put in building WTs that will resist the environmental harshness of the offshore environment and avoid these specific environmental risks, which makes not only CAPEX, but also O&M costs even more expensive [61,62].…”

“…One of the best ways of enhancing efficient operation and therefore, life extension, is by using Structural Health Monitoring and Condition Monitoring (SHM/CM) Systems, as part of a Condition Based Maintenance (CBM) paradigm with smart loads management [63]. CBM strategies allow the planning of maintenance activities and inspections based on the data of SHM/CM Systems [64].…”

“…This will reduce the power production but at the same time it will increase the service life of the WTs, decrease maintenance costs and increase WF's efficiency. Some simulations carried out by [60] showed that when a turbine is deareated, diminishing the power production by 5%, a fatigue life extension in the blades reached 300% due to a decrease of 10% in the equivalent loading.…”

Wind Turbine Fault Detection through Principal Component Analysis and Statistical Hypothesis Testing

“…The SHM techniques are based on the idea that the change in mechanical properties of the structure will be captured by a change in its dynamic characteristics [5]. Existing techniques for fault detection can be broadly classified into two major categories: model-based methods and signal processing-based methods.…”