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It is standard practice to utilize meteorological masts to measure wind data for a potential future wind farm. High-quality data from a site is a key requirement for optimizing the design of the wind farm, predicting the future energy production of the wind farm and also as an input to selecting the type of wind turbines for your particular wind farm.

A wind turbine obtains its power input by converting the force of the wind into torque acting on the rotor blades. The amount of energy which the wind transfers to the rotor depends on the density of the air, the rotor area, and the wind speed.

The wind speed is extremely important for the amount of energy a wind turbine can convert to electricity: The energy content of the wind varies with the cube (the third power) of the average wind speed, e.g. if the wind speed is twice as high it contains 23 = 2 x 2 x 2 = eight times as much energy.

In practice this means that it is really important to carefully select all the equipment that you are planning to use for your wind measurement campaign. Keep in mind that the level of uncertainty in the energy yield prediction will be estimated based on all inputs to the energy yield prediction. Consequently, your wind measurement campaign should represent the wind climate across the entire site. At complex sites this often means several wind measurement masts must be deployed.

A typical wind measurement system:

  • Data logger
  • GSM/GPRS communication system
  • GPS module for precision timing and synchronization
  • Anemometers
  • Wind vanes
  • Barometric pressure sensor
  • Temperature / humidity sensor

Wind Resource Assessment

Industry standards

There are several standards and guidelines helping developers to perform an adequate evaluation of the wind conditions. However, the industry is also following some general industry standards when it comes to which sensors to use. Feel free to contact our technical sales team for recommendations and advice on instrumentation.


IEC 61400-12-1

The IEC 61400-12-1 is the most important standard for wind measurement. This standard identifies how a met mast must be installed including boom length as well as the quality of the sensors. It also defines a set of criteria with regard to data quantity and quality.



Power Performance Measurement

Power Performance Measurement is a standard measurement to determine the compliance of the measured turbine power curve with the guaranteed power curve. It is done to verify the turbine manufacturer’s power curve because without this measurement, an underperformance claim on the contractual power curve warranty is unlikely to succeed.
A meteorological mast installed upstream from the turbine is used to gather hub height measurements of wind speed, wind direction, temperature, pressure and other variables in relation to the power produced by the turbine.

Power Performance Test



Site Calibration

In complex terrains and according to the international standard IEC 61400-12-1, a site calibration must be carried out on sites where wind speeds at the meteorological mast location are not the same as at the center of the wind turbine rotor. The flow distortion factors will then be used during the power curve test.

Site Calibration


Measnet

MEASNET is a co-operation of companies which are engaged in the field of wind energy and want to ensure high quality measurements, uniform interpretation of standards and recommendations as well as interchangeability of results.
MEASNET plays a vital role in harmonizing multiple requirements and standards to ensure that the measurements across different companies are comparable, and maintains a high quality. There are several guidelines set by Measnet:

The anemometers we supply are all calibrated by a Measnet-certified wind tunnel together with a certified calibration report according to international standards. Example of a Measnet calibration certificate.