Power curve measurement for wind turbines (IEC 61400-12-1)
Power curve measurement for wind turbines: objective, manufacturer-independent and metrologically sound, for more yield and security in the wind farm.
Every wind turbine makes a technical promise: its power curve. But what about actual performance in operation? Are the expected yields achieved? Are there undetected losses? Is the turbine running efficiently? With power curve and performance measurement you get clear answers, objective and metrologically sound. The power curve describes how much electrical power a wind turbine delivers at which wind speed. The turbine starts up in productive wind, reaches its rated power from the rated wind speed and shuts down when the wind is too strong. Because the power available in the wind rises with the cube of the wind speed and the turbine follows this curve below rated power, even small deviations of the curve have a marked effect on the annual yield.
The IEC 61400-12-1 standard specifies how the power curve of a single turbine is measured at the site: meteorological quantities and turbine signals are recorded simultaneously, over a period long enough to produce statistically reliable data. The wind measurement mast stands at a defined distance from the turbine, according to the standard roughly two to four rotor diameters, and must have free inflow. In difficult terrain or with disturbing neighbouring turbines, a site-specific calibration may be necessary. From the measured curve, the annual energy yield can be calculated for reference wind distributions, assuming 100 percent availability. Every result is reported with a consideration of measurement uncertainty.
The standard describes procedures for measuring the power curve of individual grid-connected wind turbines; its scope depends on the edition used. It creates a common, reproducible measurement basis for manufacturers, planners, authorities and operators. The measurement assesses a specific turbine at a specific site; for comparisons between turbine types, site conditions and data filtering must be taken into account. The measurement is carried out by our accredited testing body, the EWS Testing Center, to internationally recognised standards (IEC 61400-12-1). We adapt the measurement concept individually to your site and use current measurement sensors. This way you identify optimisation potential, secure yield claims against the manufacturer and increase the profitability of your wind farm. With the turbine manufacturer we communicate technically soundly and solution-oriented on an equal footing, and you receive concrete recommendations for increasing yield.
In supply contracts for wind turbines, power curve, availability and noise are often guaranteed. Tests after takeover show whether the guaranteed values are achieved, and where they are not met, contractual penalties are often provided. Anyone who wants to assert claims needs reliable data before warranty and liability periods end. An independent power curve measurement provides this data basis, for operators as well as for investors. How such guarantees are negotiated is shown by the tender for wind turbines. Before regular operation, the turbines are inspected during technical acceptance. For wind farm operation we offer further measurements, such as sound emission measurement and frequency analysis and partial discharge measurement. The wind data from planning are based on wind measurement using mast, LiDAR or SoDAR.
