INSPECTION, REPAIR & MAINTENANCE FEATURE SPONSOR
The value of temporary instrumentation and measurement
The purpose of a measurement system is to provide the quantitative data necessary to make educated decisions. Temporary measurement methods are often utilised with wind turbines due to the large scale of components, remote location and the dozens of turbines making up a single wind power plant. Temporary measurements can be as simple as using a scale to measure distance, whilst temporary instrumentation systems may record measurements at 25,000 samples per second from multiple sensors.
TEMPORARY INSTRUMENTATION SYSTEMS Wind turbine owners and operators are beginning to use temporary instrumentation systems to measure wind turbine loads. Many wind turbine manufacturers are offering modifications that will increase a windfarm’s AEP. These methods include: blade modifications (vortex generators, tip extensions), micro-siting and turbine controller software changes. Increased energy production is tempting to the owner but comes with the uncertainty of negatively effecting the loads on the drivetrain. Increased loads could reduce life or cause premature failures.
Some operators are choosing to validate the OEM’s modification by measurements of main shaft torque and bending – this can be supported by use of data loggers and strain gauges which can be installed uptower in a day. The measurement period is continuous for multiple weeks, ideally before and after the performance modification. The data is remotely accessed over cellular network and analysed for torque, tilt and yaw moments in time series, frequency spectrums and loading histograms (LDDs) which can be validated against IEC Standard 61400-13.
CAUSE AND EFFECT EXERSISE
Temporary measurements are often used during Failure Root Cause Analysis (RCA) to determine primarily failure cause and corrective action. Failures of wind turbine components can be costly, especially if impacting a batch or an entire fleet. A cause and effect exercise can be used to identify all possible causes and a strategy for addressing each of them.
Temporary measurement systems can be used to investigate the more complex contributors to the failure. Relatively simple static measurements with dial indicators, digital calipers and laser measurement can determine drivetrain alignment, mainframe mounting position, bearing preload.
Jesse Graeter
Specialised data acquisition systems can be used to collect dynamic measurements while a turbine is operating, for example portable vibration systems, can be used to assess rotor imbalance or shaft misalignments. Proximity sensors can monitor component displacements, such as the gearbox’s motion relative to the mainframe. Measuring the main shaft torque and bending can also benefit an RCA investigation.
In some instances a simple physical dimension is desired, yet the limited access or large size of wind turbine components, can make these measurements challenging.
SIMPLE MEASUREMENTS The ability to simply measure the length, width and depth of the feature could be enough to responsibly manage the continued operation of the gearbox.
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www.windenergynetwork.co.uk
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