This functionality aims to help users come up with a legal and efficient noise reduced operating mode strategy for sites which are noise constrained and for turbine types which can be operated in noise reduced mode (e.g. Vestas, Nordex, etc.)
This can be particularly useful for sites in areas which have different noise regulations during day and night. The layout can be designed for the daytime noise limit and then an NRO mode strategy can be developed to comply with the stricter night-time noise limit. Openwind can come up with strategies for switching off turbines but is generally a lot more effective when there are several NRO modes available. In order to use this functionality, the various NRO modes need to be defined as separate turbines types and then associated with a primary turbine type which is the same turbine but without any noise abatement. This is the purpose of the Noise Reduced Operating Modes dialog. Once the NRO modes have been associated with a primary turbine type, running the menu item Operations->Check Legality will trigger NRO mode strategy creation starting with the closest turbines to any environmental sensors whose noise limit is not compliant. Turbines will have their turbine types changed in order to comply with the noise limits at all environmental sensors. If the noise limit only applies for night-time, the turbine scheduling interface can be used to copy the current turbine types into a schedule using a button on the site layer turbine scheduling tab.
The NRO mode creation process triers to minimise the hit to the energy capture whilst only downgrading the turbine operating modes just enough to meet the noise limits at the environmental sensors. This process is not guaranteed to be optimal.
When optimising with noise limits set and NRO modes enabled, turbines can be placed in areas where they don’t comply with noise restrictions and they are then downgraded (and potentially switched off, thus generating no energy) until the sound limits are all respected. To disable this behaviour, simply disable the automatic noise strategy creation until layout optimisation is complete.