• As part of the approval of your wind park under immission control law, you want to verify the compliance with sound power levels and document their correct determination?
• The newly developed prototype of your wind turbine requires the measurement of acoustic emissions as a basis for the type certification?

As a member of the Fördergesellschaft Windenergie (FGW e.V.) (Society for the Promotion of Wind Energy) we perform measurements of emitted acoustic noise and measurements for acceptance tests according to IEC 61400-11 and FGW guidelines. Sound immission control particularly deals with questions of noise propagation outdoors. The objective is to ensure compliance with limit values (Technical Instructions on Noise Abatement) in order to protect the people in the vicinity.

The central success factor for sound emission measurements is a fast reaction time under favorable wind and weather conditions. With branches in Höchberg near Würzburg, Hamburg and Berlin, we can carry out measurements flexibly and efficiently in both southern and northern Germany.

The efficiency of our measurements has also significantly increased with our wireless measuring system RoBin (link to Tab): The time from our arrival at the wind turbine to the start of the measurement is only about 30 minutes due to the simple setup. For example, several wind turbines and several operating modes can be measured in accordance with standards on one measuring day.

• You want to know exactly which parts of the wind turbine increase the noise level or cause tonalities? You also want to know how these tonalities can be eliminated?

In order to be able to plan and initiate noise abatement measures, it is necessary to know the exact source of the noise. We have various measuring systems to cover almost all cases. The acoustic camera Noise Inspector locates sound sources and displays the results as an acoustic photo or video.

We support you when you are confronted with acoustic issues – whether you just have to locate a sound source or want to develop noise abatement measures.

Our references in the area of sound source location (extract):

• Rhein Energie AG
• GE Wind Energy GmbH
• Enercon
• Vensys Energy AG
• MAC Energysystems GmbH & Co. KG

The main component is a sound level meter for detecting noise via a double-shielded external microphone. A flexibly applicable data logger with six freely configurable analog interfaces, a USB and a fieldbus connection registers the operating parameters of the wind turbine. Weather data is recorded with meteorological sensors with the required class of accuracy.

Data transfer and power supply are provided via WiFi and lithium battery technology. A radio remote control is used to mark the status of the measurement (operating or background noise) and to identify interfering noises. The wind bins are managed automatically in real time. The course of the measurement can be conveniently monitored remotely via tablet.

The evaluation of the data necessary for the sound power determination is done with our sound analysis software RoBin.Post, which is tailor-made for wind energy. Here, both the data recorded directly with RoBin and measurement data recorded elsewhere can be processed. The data evaluation according to IEC 61400-11 and FGW TR1 (Edition 2.1 and 3) works at the push of a button. The automatic report output – directly after the measurement – makes the process particularly efficient.

Vibrations in the gearbox of a wind turbine can cause tonalities (noise with a fixed frequency, e.g. whistling noise). These tonalities are particularly unpleasant for people and thus they have to be specifically considered in the evaluation of noise emissions. In accordance with legal standards, surcharges are therefore assigned to the determined sound power level of the wind turbine. With this surcharge, the authorized limits for noise emissions or the contractually agreed noise levels may be exceeded.

Therefore, tonalities have to be reduced. In the wind energy sector, Wölfel has many years of experience in the application of active and passive absorbers, which compensate the vibrations at their source before they can spread. This is achieved with precisely applied counter-vibrations.

By moving the black dots you can calculate your individual payback period with our interactive tool:

Noise-reduced operation of your WTG can massively reduce the yield of your wind farm. With ADD.Soundyou minimize tonality and can return to the normal operation mode. This calculation includes all costs including installation.