The service life of a wind power installation should be at least 20 years, and the amount of maintenance and servicing work required in order for this to be achieved depends on a range of factors. Turbulent air flows in inland areas create difficult wind conditions that may cause damage, and while the wind usually blows in a favourable direction in coastal areas, the salty air and moisture here also have an impact on the installations. Matters are further complicated by issues of accessibility in the offshore sector, where service technicians need to be transported to their destinations by boat or helicopter.
“Wind energy is a challenging field of application in terms of servicing and maintenance. Accordingly, our customers rank among the pioneers in this area as regards to condition monitoring,” explains Olaf Prein, Global Segment Manager Energy. “In the field of wind energy, essential tasks include making sure that any overloads or anomalies, such as in the motors or brakes, are detected at an early stage, and responding quickly to poor cooling fan performance or the risk of the rotor blades icing up. In order to achieve this, we combine our industry-related and technological expertise to create a range of solutions that give operators the necessary transparency and methods of automated countermeasure implementation.”
In future, screw connections will be tested using ultrasound, with alarms triggered automatically in the event of deviations
Ultrasound-based screw monitoring
In the development of specific system solutions, Weidmüller focuses on various issues, including that of screw monitoring. The application of conductive paint onto a plastic sensor on the screw nut combined with a signal transmission in continuous loop allows for permanently reliable monitoring. As soon as the paint cracks, which is a sure sign of a precarious or already broken screw connection, an automatic alarm is issued, which also includes information on which screw is affected.
“Connections are our core business, and making sure that they remain intact is our ultimate aim. When this objective is applied to the screw connections found in a
wind power installation, this means that we are of course already thinking ahead about ways in which screw defects can be detected at an even earlier stage,” claims Prein. “In future, an ultrasound signal will be sent to the connection and the signal propagation time measured in order to monitor the screw pre-tension force. If deviations from the permissible measurement corridor are noticed, then this will trigger an immediate alarm. The software for transmitting the corresponding measured values will be integrated into u-remote, our remote I/O solution, making it part of a flexible industrial system.”
Increased yield thanks to anti-icing
The material monitoring solution on the rotor blade is also designed to ensure early detection. Visual strain gauges record any changes to the shape of component surfaces caused by strain, pressure or vibrations. If deviations are detected, the system immediately initiates defined measures in order to prevent failures and keep damage to a minimum.
The rotor blade is also the focus of the anti-icing system. As soon as the system detects climate conditions that could potentially lead to the formation of ice, it activates special rotor-blade heating systems developed by Weidmüller in cooperation with ADIOS Patent GmbH. “This means that system yields don’t need to be ‘put on ice’ even in cold regions,” explains Prein. “Current studies show that without anti-icing mechanisms, we could experience losses in yield of up to 50 % during the winter months. To ensure that our customers don’t lose out on this yield, we have designed our system solution so that it can easily be retrofitted to existing systems.”
As well as the cold, lightning strikes are another climate-related risk that needs to be anticipated. As part of the Weidmüller lightning-measurement system
Application-specific solution for recording the blade status and automatically starting a heating system if ice is forming
with integrated surge protection, elevated current pulses are detected wirelessly and documented. As well as the purely quantitative measurements, the results are also automatically recorded with the corresponding dates and times, meaning that the strain on the protection systems can be tracked precisely and the service technician requirements planned accurately.
Finally, the optimal positioning of the blade in the wind allows for a sensor-based solution for recording the blade’s position, delay angle and vibration. Based on the recorded data, the pitch and rotor angles can be automatically adapted to the specific wind conditions, thereby effectively countering a mechanical overload.
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Published in November 2015