Wind Turbines' Acoustic Emission Assessment Theory & System Based On IEC Standard

Focusing on IEC 61400-11 based wind turbine's acoustic emission assessment theory, a QLV-WTA-01 assessment system specially used for wind turbine's acoustic emission measurement has been presented.As an engineering project based on multiple subjects, background knowledge such as wind turbine's basic structure, sources of wind turbine sound, the history of IEC 61400-11, labs&enterprises which can perform the MEASNET approved measurements, instruments used and their characteristics have been introduced summarized from quite a lot of relevant materials, depending on which a better scheme to perform reliable and efficient measurement with a low cost.Specifications given in IEC 61400-11 to ensure this process'consistency and accuracy have been introduced. A conclusion that the correlation of nacelle wind speed and electrical power output is typically better than the mast one. Theory elements of the calculation formula used for the apparent sound power level of wind turbine have been discussed for the first time, and detailed calculation procedure of tonality and audibility integrating narrowband analysis and psychoacoustics is described, based on which an improved wind turbine's acoustic tonality analysis using an IFE based order analysis approach has been presented. During this time, an improved algebra based resampling-time-flag algorithm has also been obtained. Besides which, methods on standard wind speed calculation, average turbulence intensity, and type A uncertainty have been discussed.A virtual instrument architecture based QLV-WTA-01 IEC assessment system specially used for wind turbine's acoustic emission measurement has been developed, functions of which includes: dynamic&DC signal measurement, data file management, standard wind speed calculation, sound power, 1/3 octave analysis, tonality and audibility at integer wind speed, turbulence, uncertainty, etc.Mass field experiments have been carried out in Dabancheng No. 2 Wind Farm (Xinjiang, China) during July 2007, analysis results of which agree with the design parameter and the subjective judgment, and the assessment result acts in accord with the one given by MEASNET member.