Sensor Knowledge
Anemometer Knowledge
Anemometers measure the horizontal wind speed (velocity). This parameter is crucial for any wind site assessment.
Cup anemometers are the general standard type of anemometer. They are robust and resistant to turbulence and skew winds caused by masts and traverses.
Each anemometer should be individually calibrated and equipped with a certified calibration report according to international standards (e.g. MEASNET).
At least two anemometers have to be installed on a met mast. Most anemometers can be equipped with electronically regulated heating.
Wind Vane Knowledge
- Wind vanes determine the wind direction. The evaluation of the wind direction ensures the best possible position of wind turbines.
- It is essential that a wind vane covers an entire 360° degree radius, without a north gap.
- Cheaper wind vanes often have lower quality internal electro-mechanic fittings, which limit their life span, and a considerable north gap.
- Most wind vanes can be equipped with electronically regulated heating.
- Digital (TMR) and potentiometric (POT) wind vanes are available.
Temperature Humidity Sensor Knowledge
Temperature sensors measure air temperature, while humidity sensors measure air humidity. Both sensors are often applied in combination to reduce cost.
The calculation of the air humidity does not directly influence a wind site assessment, but knowing this parameter helps assessing the potential danger of ice build-up at the measuring location.
Air Pressure Sensors Knowledge
Air pressure sensors (barometers) measure the air pressure. Air pressure and air temperature should be evaluated for an accurate wind site assessment, although this data could be obtained from nearby weather stations and thus they are not considered an essential part of a measuring system.
Precipitation Sensor Knowledge
Precipitation sensors are designed to measure the quantity and intensity of precipitation striking the earth’s surface.
Precipitation is best measured with a tipping bucket device.
Ultrasonic anemometers Knowledge
Ultrasonic anemometers measure the horizontal wind speed and direction as well as the acoustic virtual temperature.
Pyranometer Knowledge
Pyranometers (global radiation sensors) measure global radiation. They are also used as reference instruments due to their measurement precision.
The use of this sensor is crucial for measurements with solar-powered applications. It is advisable to use only classified and calibrated pyranometers to ensure accurate results. Adjustable feet and a level allow easy horizontal adjustment.
LiDAR Knowledge
Remote sensing systems have become more and more popular in the wind industry as a supplement to the traditional met mast. Remote sensing systems can be applied to complement a wind site assessment campaign or for wind farm monitoring.
The systems measure the wind conditions from the ground up to a height of 200 meters. Thus the wind speed and wind direction up to rotor blade tip-height or for the whole rotor blade area can be used to calculated the wind energy yield forecast.
