The Effect Of 10kV High Voltage Transmission Line On Magnetotelluric Data And Data Processing

In the fieldwork,we can artificially avoid very serious sources of interference,such as power plants.However,due to the development and popularization of social science technology,even in villages and towns,the impact of 10 kV high-voltage transmission lines can't be avoided.Due to the unavoidable environmental interference,it is very difficult to obtain high signal-to-noise impedance for the field acquisition of magnetotelluric sounding,which also has an impact on inversion and geological interpretation.Therefore,it is very meaningful to study the data processing of magnetotelluric sounding under the common 10 kV noise interference environment.High quality data is the basis of later inversion,and also improves the accuracy of interpretation.This paper will focus on the characteristics of magnetotelluric sounding data from Xiong'er Mountain area affected by 10 kV high voltage transmission line.In the field experiment,moving acquisition system to change the distance between interference source and acquisition point to study the influence characteristics of 10 kV high voltage transmission line on acquisition experiment,and the data obtained are processed traditionally.By comparing the time series,apparent resistivity curve and phase curve of data from different distances of 10 kV high voltage transmission line,we can obtain the characteristics of interference on 10 kV high voltage transmission line.Finally,through the data acquisition of several similar interferences,we can get a number of data affected by 10 kV noise,and find a more effective method to deal with the interferences.The processing of magnetotelluric sounding data mainly includes time series preprocessing,spectrum estimation,power spectrum calculation,tensor impedance estimation and apparent resistivity and phase curve acquisition.In this paper,I will improve the traditional data processing methods from the aspects of time domain and impedance estimation,so as to obtain higher signal-to-noise ratio data.Under the traditional processing system,the influence of 10 kV noise has not been eliminated,so EMTF processing system is used to process the collected data.After processing by EMTF,a more smooth apparent resistivity curve and phase curve can be obtained,and the effect of data recovery in medium and low frequencies is very good.Compared with traditional processing methods,there are more steps.However,more reliable data can be obtained,and the artificial influence of manual selection of power spectrum can be avoided,which is more efficient than manual selection of power spectrum.After choosing the appropriate processing system,the independent component analysis(ICA)method is used to separate the signal and noise from the time series of magnetotelluric sounding data in the time domain.After obtaining the new time series,the above processing system is used for Fourier transform,and Robust estimation method is used for tensor impedance estimation.Finally,a smoother apparent resistivity and phase curve can be obtained.