Sea Technology

APR 2017

The industry's recognized authority for design, engineering and application of equipment and services in the global ocean community

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www.sea-technology.com April 2017 / st 25 network and SCADA or through dedi- cated systems where appropriate. Data can be made available to other opera- tional sites if required. Instrumentation is typically con- nected to a data acquisition unit (DAQ) located on each wind turbine, and each DAQ provides local storage and ability to forward the data in cases of communications failure. An Ethernet data connection supports high-speed data acquisition. The number, type and position of sensors to be installed are designed for each application, depending on the details of the structure and wind tur- bine equipment. Typically, the data to be collected are environmental, struc- tural, mechanical and electrical. The sensors for environmental data acquisition include those for mois- ture and humidity, temperature, wind speed direction, wave height and di- rection, water current speed and di- rection, and levels of scour. Typical structural sensors include strain gauges and accelerometers. Sensors for the mechanical systems measure vibra- tion of equipment and particulates in lubricants, with the electrical systems also monitored. Additional data can be added to the overall picture that may include metrology and date-time infor- mation from satellite communications. The key to extracting real value from the monitoring system is to integrate the acquired data with mathematical models of the systems. As an example, consider the structures supporting the wind turbine. Potential problems that might be of interest are grout slippage at tower- foundation interfaces, degradation of the foundation, and change of sup- port to the foundations from scour. Sensors for monitoring the structure can acquire data on strains within the tower (strain gauges) at multiple loca- tions. The inertial sensors can gather data on the acceleration and position of the tower as it moves. The real value of these data comes when they are compared to the predicted behavior of the structure using methods such as ambient vibration monitoring (AMV). AMV uses the measured response of the structural system to environmental or other ambient loads. The natural fre- quency and damping can be calculated from acceleration data and the current condition of the structure determined by comparison to models. If there are sufficient sensors, then the location of potential problems can be determined. The appropriate position, number and type of sensor are determined in ad- vance by structural modeling. Special- ist knowledge of structural mechanics is required to design and build the ap- propriate mathematical models. Sonar Systems info@edgetech.com USA 1.508.291.0057 CHOOSE THE LEADER IN UNDERWATER TECHNOLOGY Acoustic Releases and Transponders USBL Positioning and Tracking An Aquaterra IMU unit, supplied by Aquaterra and Proeon and installed on an offshore facility.

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