The X-Energy sub-project X-Eptance Impulse has set itself the goal of increasing the sustainability and acceptance of wind turbines. To this end, a low-cost, synchronous, multi-channel measurement system for acoustic signals is being developed using state-of-the-art, highly integrated components. This is used for the permanent measurement of noise emissions from wind turbines and their minimization by the turbine control system. In addition, a noise database is being developed for early acoustic fault detection.
At the Curslack Research Wind Farm, measurements are carried out using a commercially available acoustic camera. The data obtained forms the basis for the noise database currently being developed and provides initial indicators for individual noise patterns. In the next step, measurements will be carried out with the prototype and the results compared with the existing acoustic camera.
Acoustic camera
The acoustic camera is a versatile measuring device: it can be used to measure both sound levels and immissions of the sounds occurring at the camera's location. The latter can be localized and analysed separately according to the individual sound sources. With up to 120 microphones, the acoustic camera records the noise from all wind turbines and other sources in the vicinity. It determines the time differences of the individual sounds between the microphones. With this additional information, the origin of one or more sounds can be determined using a process called beamforming. Depending on the application, a different arrangement (array) of microphones is required. Accordingly, there are different arrays that are particularly suitable for certain frequency ranges and distances.
Data evaluation
The acoustic camera can display the sound levels of individual sources in color, just like a thermal imaging camera. This makes it possible to visualize individual sound sources of a machine, a room or an entire environment. In addition to visualization using 2D or 3D images, other analysis options are also available. The observation of individual frequencies over time in the spectrogram, for example, makes it possible to visualize recurring noises from a wind turbine or to distinguish them from the rising and falling roar of a passing aircraft. With these and other tools, a comprehensive analysis of ambient and turbine noise is possible.
