| With the rapid development of HVDC transmission technology,the noise problem in the operation of HVDC converter station has been gradually concerned by the public.The converter transformer in the station is the main noise source,and its noise prediction accuracy directly affects the noise prediction model of the whole converter station in the later period.Therefore,it is particularly important to accurately obtain its sound power,which is of great significance to accurately predict and effectively control the noise of the converter station in the later period.At present,sound intensity method,sound pressure method and vibration velocity method are used to directly measure sound power of sound source,but the process is complicated,the measurement requirements are high,and the measurement error is large in complex environment due to factors such as coherent sound field,so it is not suitable for practical engineering application.At the same time,sound barrier is the main noise reduction measure in the converter station,but its structure size mostly adopts empirical method and trial and error method,which has high cost and poor economy.To solve the above problems,this paper proposes an acoustic power inversion algorithm based on the measured values of multiple measurement points.Based on reliability probability and statistics,the algorithm identifies and removes the measured points with large measurement errors,so as to achieve more accurate acoustic power inversion calculation.In addition,based on optimization design theory,an optimization design method of sound barrier size is proposed,which takes the cost of sound barrier engineering as the objective function and has the lowest cost under the premise of ensuring the noise reduction effect.The results of this paper can improve the prediction accuracy of the converter station and the economic benefit of the implementation of the control scheme.It mainly includes the following contents:Firstly,the noise source of transformer is analyzed and its radiation characteristics are briefly introduced.By collecting sound pressure level of transformer near point measurement point,it is found that the noise is mainly broadband noise of 100 Hz,200Hz,400 Hz,500Hz and 600 Hz,and several methods for directly measuring sound power of sound source are described in detail: sound pressure method,sound intensity method and vibration velocity method.Secondly,according to ISO9613-2 calculation method of outdoor sound propagation,based on equivalent source method,the mathematical model of sound power of sound source is established.Use transformer field around A large number of measuring point measured sound pressure level data,and through the establishment of transformer noise prediction software Cadna/A prediction model for acoustic attenuation of each measuring point for sound power source based on the genetic algorithm inversion stability to solve mathematical model,so as to realize sound power transformer inversion calculation,combined with the reliability theory,identify and eliminate these points,in this way,the calculation accuracy of sound power of sound source is improved,and the number of measuring points is preliminarily studied and optimized.Then,based on the principle of noise reduction of finite-length sound barrier and the attenuation algorithm of engineering sound barrier,a simplified algorithm of insertion loss of finite-length sound barrier considering diffraction is proposed.In order to minimize the comprehensive cost of sound barrier in practical engineering,the optimization design model of structure size of sound barrier was established,and the optimal value of the objective function was solved by using Matlab optimization toolbox.Finally,COMSOL acoustic diffusion equation physical field interface was used to verify the finite element simulation of the transformer.The measured data of the transformer was compared with the software simulation value.The results showed that the errors of other measuring points were less than 1d B except those which were greatly affected by the coherent sound field;The noise prediction software Cadna/A is used to verify the noise reduction effect of the optimized sound barrier.The results show that the optimized scheme is feasible in practical engineering and the cost of the project is saved about 20.6%. |
