Installation of wind measurement systems
The measuring system should always be installed by professionals - no matter whether it is a met mast or a remote sensing system.
The correct set up of the met mast and its booms as well as position, type and quality of the measurement instruments has been defined in internationally accepted standards and guidelines: IEC 61400-12-1, MEASNET and the German TR6 guideline.
The evaluation of wind speed is crucial for wind site assessments. At least four anemometers are required to determine a wind profile that enables wind speed to be evaluated. The anemometers should be mounted onto the mast at different heights. The “top” anemometer should be mounted at the very top of the mast, and ideally should be at the same level as the hub height of the planned turbines. It is essential that unobstructed wind can reach anemometers from every direction.
Servicing high-level anemometers is not always possible, as masts can be very high; a second, back-up anemometer should be installed slightly below the top anemometer. At least two additional anemometers should be mounted at the middle and the lower level on the mast. On taller masts, several anemometers are installed at regular height intervals to give the most accurate wind meas-urement data.
Wind vanes are installed to determine the wind direction. A wind vane is best positioned just below the top anemometer. It is recommended installing 2 or 3 additional wind vanes into the system. For very wide masts (e.g. a converted radio mast) sensors should be installed in pairs (1 on each side of the mast) to ensure that at least one sensor delivers the correct wind data.
Humidity-temperature sensors should be mounted with a weather and radiation shield at a height of 10m.
Air pressure sensor
The air pressure sensor should be installed inside the data logger’s steel cabinet, provided that the cabinet is permeable to air.
Data loggers are the core of every wind measuring station and should be safely installed in a weatherproof and robust CE certified steel cabinet.
Several potential components could be added in the steel cabinet, such as GSM/GPRS communication module, barometric pressure sensor, battery and surge protection. The steel cabinet offers protection against damage from weather, condensation and vandalism.
Finally the obstacle lights should be mounted at the top of the tower. The regulations on installation of obstacle lights vary largely from country to country.