New forms of instrumentation can have a significant impact on reliability engineering of wind turbines. By using techniques for synchronized measurements on wind turbines, their subsystems, as well as on the wind field in front of turbines, makes it possible to see the correlation between the wind fields and their loading on turbine components, as well as instrumenting the downwind wind field flow and turbulence in a wind farm.
The instrumentation is based on precisely synchronized data acquisition (hereafter referred to as nanosynchronization) and has already been demonstrated on several previous wind turbine projects as described in other sections of this blog.
The following are examples of how this technology could contribute to the Reliability of wind turbines:
1. Mapping of input wind field: By using multiple synchronized wind/pressure/turbulence transducers arranged in an array in front of a wind turbine, it will be possible to map the dynamic wind field impacting the turbine. Such an array could be mast mounted, or transducers can be hung from one or more tethered balloons in front of a turbine.
2. In situ wind turbine data acquisition (structural, drive train, electrical sub-systems) . Pressure/strain/transducers on the impacted wind turbine can acquire precisely synchronized data thus showing the dynamic loading on turbine wings, tower, nacelle. The synchronized data can be used for verification of analytic models (FEM) as well as for building of high resolution modal analysis models, including ODS (Operational Deflection Shapes) . In addition, by mounting pitot tubes on wind turbine blades, the “instantanenous” power of the turbine can be derived. The transducers can also be mounted various places on or inside the structure using advanced wireless synchronization techniques, also inside structures where the GPS signal may not be accessible. Transducers and their associated high speed data logging systems may be placed on rotating sub-systems, where wireless data transfer, or transfer via slip rings may not be feasible. Any electrical sub-system of the turbine can also be instrumented, since the instrumentation package is battery operated and hence will float relative the any voltage present.
3. Correlation between input wind field and structural/electrical/drive train loading: by combining points 1 and 2 above (wind field mapping and turbine data acquisition) more advanced models of real world behavior can be derived. In addition, the synchronized transducers can also be coupled to the electrical control signals of the wind turbine as well as the generator output signals and to various points along the electrical chain from power converters to the power grid and include flicker and other power quality metrics. Thus a complete instrumentation chain can be created showing the causal relationships from the wind field input to the electrical output to the grid, as well as the intermediate sub-systems in the wind turbine(s).
4. Fatigue Loading: The nanosynchronized instrumentation techniques can give data of multiple point fatigue loading, including driver trains, on the front-line turbines, as well as the downstream turbines in wind farms.
5. Scaling of instrumentation to larger, multi-point arrays: The instrumentation systems already demonstrated in practical field trials, can be down-sized significantly by simply re-engineering the existing demonstrator models using more compact design techniques. This makes it possible to deploy measurements on a greatly increased number of points, and the reduced size, weight, and cost per point makes it possible to place transducers/data acquisition systems in previously inaccessible places, or places where the weight of the system may have had a negative impact on the performance of the system being instrumented. An example of this would be loading of rotating devices, or downsizing the balloons carrying airborne transducers, thus reducing the impact on the wind field being instrumented.
Finally, many other aspects of nanosynchronization for wind turbines also include noise radiation measurements, real time control, and power quality measurements.