In order to reduce the CO2-emissions and to increase the energy efficiency, the operating temperatures of power plants will be increased up to 720°C. This demands for novel high-performance steels in the piping systems. Higher temperatures lead to a higher risk of damage and have a direct impact on the structure stability and the deposition structure. Adequately trusted results for the prediction of the residual service life of those high strength steels are not available so far. To overcome these problems the implementation of an online monitoring system in addition to periodic testing is needed. RWE operates the lignite power plant Neurath. All test and research activities have to be checked regarding their safety and have to be coordinated with the business operation of the plant. An extra bypass was established for this research and made the investigations independent from the power plant operating. In order to protect the actuators and sensors from the heat radiated from the pipe, waveguides were welded to the bypass. The data was evaluated regarding their dependencies on the environmental influences like temperature and correction algorithms were developed. Furthermore, damages were introduced into the pipe with diameters of 8 mm to 10 mm and successfully detected by the acoustic method.
To operate wind turbines safely and efficiently, condition monitoring for the main components are of increasing
importance. Especially the lack of access to offshore installations increases inspection and maintenance costs.
The current work at Fraunhofer IZFP Dresden in the field of monitoring of wind turbines is focused on the development
of a condition monitoring system for rotor blades.
A special focus lies on the application of optical technologies for communication and power supply. It is not possible to
introduce electrical conductors into the rotor blade since it might cause tremendous damages by lightning.
The monitoring concept is based on a combination of low frequency integral vibration monitoring and acoustic
monitoring techniques in the frequency range between 10 and 100 kHz using guided waves. A joint application of
acousto ultrasonics and acoustic emission techniques will be presented. Challenges and solutions of such a field test like
sensor application, data handling and gathering as well as temperature variation are described.
For comprehensive fatigue tests and surveillance of large scale structures, a vibration monitoring system working
in the Hz and sub Hz frequency range was realized and tested. The system is based on a wireless sensor network
and focuses especially on the realization of a low power measurement, signal processing and communication.
Regarding the development, we met the challenge of synchronizing the wireless connected sensor nodes with
The sensor nodes ware realized by compact, sensor near signal processing structures containing components for
analog preprocessing of acoustic signals, their digitization, algorithms for data reduction and network
communication. The core component is a digital micro controller which performs the basic algorithms necessary
for the data acquisition synchronization and the filtering. As a first application, the system was installed in a
rotor blade of a wind power turbine in order to monitor the Eigen modes over a longer period of time. Currently
the sensor nodes are battery powered.