Foundation Monitoring Systems for optimized O&M and lifetime assessment on offshore wind turbines

50 %
50 %
Information about Foundation Monitoring Systems for optimized O&M and lifetime assessment...
Technology

Published on January 30, 2014

Author: pieterjanjordaens

Source: slideshare.net

Foundation Monitoring Systems for optimized O&M and lifetime assessment PO.ID 201 Christof Devriendt (1-4) Yves Van Ingelgem (1-5) Gert De Sitter (1-4) Daan De Wilde (1-5) Kristof Verlinden (2) Cedric Vanden Haute (2), Pieter Jan Jordaens (3-4), Stefan Millis (3-4) (1)Vrije Universiteit Brussel (2) Belwind NV (3) Sirris (4) Offshore Wind Infrastructure Lab, (5) Zensor Abstracts Corrosion Monitoring The Offshore Wind Infrastructure Lab (OWI-lab) has a mutual partnership with Parkwind to perform foundation monitoring. A first monitoring system, which is installed on a monopile foundation of a 3 MW Vestas turbine at the Belwind wind farm, has now been running for almost two years. Recently two additional monitoring systems were installed at the Northwind wind farm. The motivation is gaining the insights that are crucial to minimize construction and installations costs of the future planned wind turbines at the Belwind concession and to extend the lifetime of existing structures and reduce their operation and maintenance costs. Offshore Wind Farms The foundation monitoring system has been installed at the Belwind and NorhWind windfarm in the Belgian North Sea. Facts Belwind: 55 Vestas 3MW V90 turbines, Monopile foundations, 46 km offshore, Water Depths : 16 – 30m The corrosion monitoring consists of the continuous monitoring of the corrosion rates, corrosion potential and oxygen concentration inside the monopile. Figure 2: Schematic picture of TP, MP, grouted connection and brackets (left) relative displacement between TP and MP during monitor period (right) Retrofit installed brackets and bearings now prevent the transition piece to completely slip downwards. The monitoring system however continues to measure the slippage of the transition piece and the loads taken by the installed brackets and bearings. An advanced grout monitoring system has recently been installed in two turbines of the Northwind wind farm. This system will allow to measure the strains inside the grout. This will be done by using optical strain sensors embedded in reinforced bars that have been installed inside the grout during installation. Facts Nothwind: 72 Vestas 3MW V112 turbines, Monopile foundations, 37 km offshore, Water Depths: 16 – 29m Figure 1: Belgian offshore windfarm-concessions Figure 3: Setup for strain-monitoring inside the grout (left) optical fiber embedded in reinforced steel bar (right) Approach Corrosion management inside the monopiles has been based on the assumption that no oxygen is present within the confined space of the monopile. The monitoring-setup at Belwind has however been able to detect that the level of oxygen inside stays high. Based on installed electrodes that are lowered inside the monopile structure measurements of corrosion rates at multiple depths are conducted. These measurements confirmed that active corrosion is present inside the monopile. It is currently being investigated how the corrosion management for these type of structures needs to be adapted and how the presented monitoring system can play a crucial role within this. Dynamic Monitoring The purpose of the monitoring campaigns at the Belwind farm and the Northwind farm is to get a precise view of how the wind turbine is changing over time and what causes the changing behavior. Several parameters are being monitored, among them: 
• Loads, displacements, strains temperatures in the grouted connection Figure 4: Measurement setup corrosion monitoring inside monopile (left) example measured corrosion rate (top right) example measured oxygen level (bottom right) and The dynamic monitoring consists of the continuous monitoring of the vibration levels, resonant frequencies and damping values of the wind turbine structure. local Life Time Assessment Continuous monitoring of stresses is essential for life time assessment. Direct measurements of the stresses at the e.g. the mud-line, 30 meter below the water level are expensive and practically unfeasible. In this case a response estimation techniques will be used to estimate Stress prediction Application the response at unmeasured locations by combining a limited set of response measurements (accelerations, Modal Analysis strains, etc.) and a Finite Element (FE) model. The FE • extraction o model will be updated based on the dynamic properties Stress prediction Application • extraction o identified by the dynamic monitoring system. • extraction o 1st Fore-Aft f=0.35748 Hz • vibration and strain levels on tower and foundation • resonance frequencies, damping values and mode shapes of the offshore structure 1st Fore-Aft f=0.35748 Hz Identifying Dynamic Parameters Measuring Accelerations • oxygen levels and corrosion rates inside the monopile 2nd Fore-Aft f=1.3849 Hz Modal Analysis in FEA software Updating FEM model Prediction Stresses • 2nd Fore-Aft f=1.3849 Hz 3rd Fore-Aft f=3.3671 Hz extraction of mode shapes • Stress prediction Application 1st Fore-Aft f=0.35748 Hz extraction of natural frequencies • extraction of displacement mode shape vectors and stress mode shape vectors Modal Analysis in FEA software • …
 Figure 4: Measurement locations accelerometers (left) example measured vibrations during 10 minutes (top right) 5 dominant mode shapes during parked conditions Grout Monitoring The grout monitoring consists of the continuous monitoring of the loads taken by the grout connection and the relative displacement between the monopile (MP) and the transition piece (TP). Those parameters are necessary to see if the grouted connection is deteriorating. Following sensors have been installed: •12 displacement sensors •6 load sensors The dynamic monitoring solution is able to detect daily variations in the vibration levels due to changing ambient conditions e.g. wave periods, wind speed and wave heights. Also small changes in resonant frequencies due to e.g. tidal level are detectable. These parameters can be exploited to asess structural integrity of the offshore wind turbine and detect changes in the dynamic behavior due to e.g. scour. Real damping ratios are very difficult to predict by numerical tools and therefore measurements on existing offshore wind turbines are crucial to verify the existing design assumptions. Damping ratios are crucial for lifetime predictions as the amplitude of vibrations at resonance are inversely proportional to these ratios. •1 temperature sensor Life-Time Assessment • extraction of mode shapes • 2nd Fore-Aft f=1.3849 Hz shape vecto shape vecto extraction of natural frequencies 3rd Fore-Aft f=3.3671 Hz • extraction of 3 tower modes Figure 6: work-flow for life-time assessment (top) Firstdisplacement mode from FE-model shape vectors and stress mode shape vectors O&M Optimization 3rd Fore-Aft f=3.3671 Hz The final step is to combine the output of the foundation monitoring system with the weather data and the business plan to achieve an optimal and informed decision to plan O&M activities on the foundations. Figure 7: Building-blocks towards O&M optimization Acknowledgements The most important observation made by the monitoring system was the confirmation that the transition piece was indeed slipping downwards on the monopile foundation as a result of the failing grout-connection. Figure 5: Evolutions of resonance frequencies of 5 dominant modes during 2 weeks of parked conditions (left) Statistics of damping values of 5 dominant modes during parked conditions with wind speeds of 0-5m/s EWEA OFFSHORE 2013 This work has been founded by the Institute for the Promotion of Innovation by Science and Technology in Flanders (IWT) in the framework of the “Offshore Wind Infrastructure Application Lab” (www.owi-lab.be).

Add a comment

Related presentations

Presentación que realice en el Evento Nacional de Gobierno Abierto, realizado los ...

In this presentation we will describe our experience developing with a highly dyna...

Presentation to the LITA Forum 7th November 2014 Albuquerque, NM

Un recorrido por los cambios que nos generará el wearabletech en el futuro

Um paralelo entre as novidades & mercado em Wearable Computing e Tecnologias Assis...

Microsoft finally joins the smartwatch and fitness tracker game by introducing the...

Related pages

Foundation Monitoring Systems for optimized O&M and ...

×Close Share Foundation Monitoring Systems for optimized O&M and lifetime assessment on offshore wind turbines
Read more

Foundation Monitoring Systems for optimized O&M and ...

Foundation Monitoring Systems for optimized O&M and lifetime ... Grout Monitoring Life Time Assessment Offshore ... offshore wind turbines are ...
Read more

PO.ID for optimized O&M and lifetime assessment - Owi-lab

Foundation Monitoring Systems for optimized O&M and lifetime ... Grout Monitoring Life Time Assessment Offshore ... offshore wind turbines are ...
Read more

Belwind - Structural Health Monitoring (SHM) | Owi-lab

... monitoring systems for offshore wind turbines ... for optimized O&M and lifetime assessment" ... of offshore wind turbines for foundation ...
Read more

Monitoring offshore structures for optimized lifetime ...

Monitoring Systems for Offshore Wind Turbines ... structures of offshore wind turbines from the foundation to the ... monitoring for optimized ...
Read more

Structural health monitoring of offshore wind turbines: A ...

Structural health monitoring systems for offshore wind turbines ... assessment of offshore wind ... for foundation SHM of an offshore wind ...
Read more

Design verification of offshore wind turbines for ...

... for foundation optimization and scour monitoring. ... O&M and lifetime assessment on offshore wind ... of Offshore Wind Turbines from ...
Read more

Christof Devriendt | LinkedIn

... (SHM) and Condition Monitoring Systems (CMS) for wind turbines, ... optimized O&M and lifetime assessment ... Foundation Christof Devriendt, ...
Read more

Condition Monitoring of Wind Turbines - Techniques and ...

... of condition monitoring systems for wind turbines ... Foundation Monitoring Systems for optimized O&M and lifetime assessment on offshore wind ...
Read more

Gert De Sitter | LinkedIn

View Gert De Sitter’s ... of the foundation monitoring systems of offshore wind turbines. ... for optimized O&M and lifetime assessment
Read more