Fraunhofer Institute for Wind Energy SystemsAt a glance
- Starting situation: Wind turbines and hybrid energy farms (e.g., wind & electrolysis) often have to operate in noise-reduced and power-reduced modes across the board in order to comply with noise limit values specified by the German Federal Immission Control Act (BImSchG) and the Technical Instructions on Noise Abatement (TA Lärm). This results in significantly lower energy yields.
- Project objective: Development of a methodology enabling simple shutdown rules to be derived from short-term acoustic and environmental measurements. For this purpose, a compact sound module (retrofit add-on) is planned, which will be installed on the turbine and transmit a binary signal (normal operation/noise-reduced operation) to the control system.
- A demonstrator deployment at the Hydrogen Lab Bremerhaven (HLB) of Fraunhofer IWES (project coordination) and the AD8 wind turbine in Bremerhaven is planned. It is expected that fewer unnecessary shutdowns will be required, which translates to higher annual operating hours and energy yields. As a consequence, hydrogen production in hybrid farms would also become more efficient. The technical solution could make an important contribution to improving economic viability and advancing regulatory development within the framework of the BMWE’s 8th Energy Research Program.
The challenge
At present, noise evaluation of wind turbines and hybrid energy farms is based on conservative forecasts in accordance with the BImSchG/TA Lärm with simplified point source models. Key parameters such as wind direction, vertical wind profiles, temperature, humidity, stability, built environment, orography, and the overlapping of multiple sources (wind turbines, electrolyzers, compressors) are not taken into consideration sufficiently. As a consequence, the turbines are often shut down across the board at night or continuously operated in reduced noise modes – even though the noise limits at the immission site would not actually be exceeded. However, high-end solutions involving continuous immission monitoring and AI-based analysis are expensive, complex, and depend on manufacturer interfaces. To date, there is no practical method enabling robust operating rules to be derived from short-term measurements at the immission site. In particular, which measurement variables are relevant, what measurement duration is required, how large the uncertainties in short measurement campaigns are, and how meteorological effects (e.g., the atmospheric boundary layer) can be simply integrated into a control logic system still needs to be clarified. A proposed solution must be low-cost, retrofittable, and accepted by permitting authorities.
The solution
The SOUNDMODUL research project addresses the problem by performing field measurements (initially for a period of one year) at multiple wind and hybrid energy farms (including AD8 and HLB), recording sound immissions, meteorological data, and turbine data in parallel, and supplementing them with microphone array measurements. The data will then be technically processed, and statistical evaluations will be employed to determine relevant parameters and necessary measurement periods. Reanalysis data and sound propagation models are utilized to record meteorological effects quantitatively and transfer them into a simple model.
The added value
From this, shutdown logic will be developed that utilizes a few locally measurable parameters to deliver a yes/no decision regarding noise-reduced operation. This logic will be implemented in a compact sound module, which can be retrofitted to turbines, integrates sensor and evaluation technologies, and transmits a binary switching signal to the turbine control system. The demonstrator will be set up in the lab, tested in the field on the AD8/HLB turbine, and validated in terms of its compliance with noise limits and potential energy yield. In parallel, authorities and stakeholders will be actively involved, results published openly, and the way prepared for widespread use and subsequent incorporation into regulations.
