Operations and maintenance of wind turbines. Professor: By: Peter Lund Ishtiaq Muhammad Advanced wind power technology Msc Mech Student Asst Professor: Juuso Lindgren. Topics discussed Today. Three parts: 1- Operation of wind turbine 2- Maintenance of wind turbine
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Peter Lund Ishtiaq Muhammad
Advanced wind power technology MscMech Student
1- Operation of wind turbine
2- Maintenance of wind turbine
3. Condition monitoring
Wind Mechanical energy Electricity
A video clip (3,5 minutes) for better show up :)
» Minimizing operational and maintenance costs
» Improving turbine performance/yield
» Lowering insurance risk
» Protecting assets
Generator and gearbox housings
Wind generator and gearbox repair
Bearing change outs and upgrades
Slip ring change outs, upgrades & turning
Grounding system upgrades
Rotor lead change outs
Housing and component rebuilds
Brush holder upgrades
Wind turbine and blade cleaning – via rope access
Wind turbine main shafts
Blade inspection–via rope access
Offshore maintenance is much and more difficult than onshore maintenance
Offshore is much and more costly than onshore maintenance because of the usage of heavy ships, helicopters and cranes etc.
Weather conditions matter too both in offshore and onshore
1- Highly variable load and speed:
Wind is an intermittent energy source. It alternates between gusting and still. Therefore, the load that these gearboxes are trying to transmit is a lot more variable than it is in a plant operation (causes accident)
2- Low gearbox safety factors: The drive system in wind turbines is designed to be compact. "They try to make things as small as they can, so that means the safety factors are lower than usual.
3- Flexible foundation: Typically, a plant gearbox and motor are mounted on a large concrete foundation or a steel structure that’s bolted to a concrete foundation. The nacelle is flexing and the rotor itself is causing lots of loads in the whole structure. This causes misalignment between the generator and the gearbox."
4- Extreme operating environment:
The turbines have to operate in extremely cold or extremely hot settings. Although the gearbox is in a nacelle and protected from rain it can still be subjected to extreme temperatures.
5- High operating temperature:
Manufacturers are resistant to adding large radiators to wind turbines. They allow these gearboxes to run pretty hot, and that means the oil viscosity gets low. When they’re rotating slowly, you don’t get a thick oil film between bearings and gears, so you get metal-to-metal contact — and that’s a problem.
Condition monitoring is a strategy where by physical parameters (such as vibration,temperature, lubrication particlesand others) are measured regularly to determine equipment condition.
This procedure makes it possible to detect machine and component problems before they can result in unexpected downtime and the high costs associated with maintenance and interrupted production.
Today's monitoring systems can handle any number of turbines and multiple data points. Using vibration sensors mounted on a turbine's main shaft bearings, gearbox and generator, systems (in tandem with software) will continuously monitor and track a wide range of operating conditions for analysis. Wireless capabilities allow operators to review data from any location with a computer or hand-held device with Internet access
An integrated on-line condition monitoring system within a typically difficult-to-reach wind turbine nacelle (like the one shown in Fig on next page) offers a powerful tool for managing day-to-day maintenance routines and consolidating risky, costly maintenance activities.
Condition monitoring is done to detect:
Unbalanced turbine blades
Generator rotor/stator problems
The following techniques, available from different applications, which are possibly applicable for wind turbines, have been identified:
1. Vibration analysis
2. Oil analysis
4. Physical condition of materials
5. Strain measurement
6. Acoustic measurements
7. Electrical effects
8. Process parameters
9. Visual inspection
10. Performance monitoring
. Vibration Analysis
Vibration analysis is the most known technology applied for condition monitoring, especially for rotating equipment. The type of sensors used depends more or less on the frequency range, relevant for the monitoring:
- Position transducers for the low frequency range
- Velocity sensors in the middle frequency area
Accelerometers in the high frequency range
Examples can be found for safeguarding of:
Oil analysis may have two purposes:
- Safeguarding the oil quality (contamination by parts, moist)
- Safeguarding the components involved (characterization of parts)
Oil analysis is mostly executed off line, by taking samples. However for safeguarding the oil Quality, application of on-line sensors is increasing.
Thermograhyis often applied for monitoring and failure identification of electronic and electric components. Hot spots, due to degeneration of components or bad contact can be identified in a simple and fast manner. Thermals cameras are used for thermography purpose
. Strain measurement
Strain measurement by strain gauges is a common technique, however not often applied for condition monitoring. Strain gauges are not robust on a long term. Especially for wind turbines, strain measurement can be very useful for life time prediction and safeguarding of the stress level, especially for the blades.
A short video clip (1 min)
Following list of references was used for this presentation.