Comment Acknowledgement for Matter Number - 21-00749 : Msg. Tracking No.: 58

 Noise from Cassadaga June 26 LEAF OFF RSG Report . Case # 14-F-0490 DMM 891.


Cause1 - icing remedy was to shut down turbine.  Please note shut down is required. A new software detection was added.
Cause2  -inflow turbulence due to close configuartion of multiple turbines. Wind WAKE?

Under its Certificate of Environmental Compatibility and Public Need (“Certificate”), the 126 MW Cassadaga Wind project (“Project”) is required to conduct post construction sound monitoring to assess compliance with specified noise limits. Sound monitoring was initially conducted during the 2021/2022 “Leaf-Off” season. This found that the Charlotte Town noise standard was exceeded around the Nordex wind turbines during certain periods when the blades were iced. In 2022, Cassadaga Wind took steps to implement mitigation to shut down certain wind turbines when icing was detected. The Project was retested in the 2022/2023 Leaf-Off season. During that monitoring period, one hour at monitoring location 3443P was found to exceed the Charlotte noise limit, also due to icing. In addition, two hours at 3443P were found to exceed the 65 dBZ certificate limit at the 16 Hz octave band. This was either due to icing or windscreen self-noise. In response, RWE implemented an additional minimization measure in October 2023 in the form of more accurate icing detection software for the Nordex wind turbines. Sound monitoring was tested again in the 2023/2024 Leaf Off season to evaluate the effectiveness of the new icing detection software during the entire icing season. The icing detection system was effective in shutting down the Nordex and SGRE wind turbines leading into icing events during the monitoring period. Five hours at 3443P exceeded the Certificate limit of 65 dBZ at the 16 Hz 1/1 octave band however. These exceedances were not related to icing and were hypothesized to be due to inflow turbulence along the T20/T19/T21 turbine string during the relatively rare times when winds are out of the south-southeast and winds speeds are above 8 m/s. In response, RWE placed T20, T19, and T21 in NRO Mode 5 when hub height winds were measured above 7 m/s and wind directions measured between 140° and 160°. This is likely the only location at Cassadaga wind that is prone to these conditions. The reason this happens at this location is the relatively close spacing between these three turbines and the way they are lined up in a row. There is only one other turbine string that has similar spacing, that is T40/T34/T26. At that location, receptors are further from the ends of the strings, which will reduce low frequency sound levels, and the closest receptors are all participating. This report discusses sound monitoring conducted during the winter (Leaf-Off) of 2024/2025 to test mitigation measures implemented for inflow turbulence conditions. Mitigation measures generally worked, maintaining sound levels in the 16 Hz 1/1 octave band to 65 dBZ or below. There were some periods when some turbines were not recognized as being inside the inflow range that were above the 65 dBZ permit condition, and a couple periods were directly adjacent to the inflow range that were above the limits. When the turbines were not recognized as being within the wind direction range, the solution is to ensure that the north offsets are correct. To solve the issue with periods just outside the inflow range, we recommend Cassadaga Wind widen the NRO range for T20 to from 130° to 170°. The directional NRO at m~SG® 1 Sound Mitigation Monitoring 2024-2025 T19 and T21 will remain at the current setting and within the current directional range of from 140° to 160°. As of the publishing of this report, both solutions have been implemented.

What are the implications for PROVISIONAL Vestas 117 4.2 when separation is less than TWO DIAMETERS and aligned within TYPHOON Wind WAKES.


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