适用于声源定位的气体绝缘输电线路超声导波传播特性研究

Research on Propagation Characteristics of Gas-Insulated Transmission Line Ultrasonic Guided Wave for Sound Source Localization

基于到达时间差(TDOA)的声源定位方法是当前气体绝缘输电线路(GIL)故障定位的主要方式,声波在GIL结构上的传输特性深刻影响着定位结果的准确性。为进一步提升故障定位精度,该文提出了考虑导波频散与多模态特性的GIL壳体声传输分析模型,以典型220 kV GIL管段为研究对象,建立声波传输有限元模型,研究了导波特性对故障定位的影响,确定了适用于故障定位的超声导波模态以及GIL非直管结构对该模态导波的衰减与时延量,通过现场定位试验验证了分析模型的可行性,为GIL声源故障定位系统的传感器配置与定位阈值设置提供了计算依据。结果表明,在20~60 kHz频带内,F(1,1)模态导波具有能量高、波形形状稳定、抗干扰能力强等特点,使用该模态导波进行故障定位精度较高。GIL非直管结构会对F(1,1)模态导波造成较大的幅值衰减与一定程度的时延,在故障定位中考虑非直管结构衰减与时延影响可以使定位误差降低60%以上。

The sound source localization method based on time difference of arrival(TDOA)is currently the mainstream method for fault location of gas-insulated transmission line(GIL).The GIL shell is similar to the cylindrical shell,and the acoustic wave propagating along the shell has the dispersion and multi-modal characteristics,which increases the difficulty of precise positioning.In recent years,people have studied the acoustic wave transmission process on GIL,but most of the studies have ignored the influence of guided wave characteristics on the transmission of acoustic wave,and the research results are deviated from the actual situation.In order to solve these problems,this paper proposes a GIL shell acoustic transmission analysis model considering guided wave dispersion and multi-modal characteristics,determines the guided wave mode suitable for GIL fault location and the attenuation and time delay caused by GIL non-straight tube structure,which effectively improves the fault location accuracy of GIL.Firstly,the dispersion curve of guided wave in the typical 220 kV GIL shell is drawn,and the guided wave modes in the frequency range of 0~100 kHz are determined.Secondly,a finite element model of acoustic wave transmission in the long-distance GIL straight pipe is established,and the propagation characteristics of guided waves are studied by applying different excitation to the model.According to the simulation results and the requirements of GIL sound source localization,the effective frequency band and guided wave mode suitable for fault location are determined.Thirdly,in order to study the location advantages of the selected guided wave mode in the GIL non-straight pipe section and the attenuation and time delay by the GIL non-straight pipe structure,the expansion joint,gas basin insulator and other non-straight pipe structures are added to the long-distance GIL straight pipe model.Finally,the selected guided wave mode is used for GIL field location test,and the influence of the attenuation and time delay of the GIL non-straight pipe structure are considered in the localization algorithm.The effectiveness of the analysis model is verified according to the location results.The results show that the propagation distance required for F(1,1)mode to separate from the original wave packet is within 2 m in the 20~60 kHz frequency band.In the GIL straight pipe section,the amplitude of F(1,1)mode is about 20 times that of the front modes,and the amplitude is attenuated up to 30%after 10m of propagation.In the process of propagation,the shape of F(1,1)mode is more stable than the modes of the rear secondary acoustic wave.In terms of temporal and spatial distribution,it is easy to distinguish with the front and rear modes,and can be used as the preferred mode for fault location.For F(1,1)mode,GIL non-straight pipe structures such as single-stage expansion joints,double-stage expansion joints,and gas basin insulator will cause 90%,96%,and 60%attenuation,and 0.6 ms,1.1 ms,0.03 ms delay.The error of using F(1,1)mode for fault location in an interval with the length of 20 m is about 1 m.Further considering the influence of the attenuation and time delay of the GIL non-straight pipe structure,the positioning error can be reduced to about 0.3 m,which proves the effectiveness of the analysis model in improving the fault location accuracy of GIL.The following conclusions can be drawn from the results:(1)The GIL shell acoustic transmission analysis model can effectively consider the influence of guided wave dispersion and multi-modal characteristics on GIL sound source localization,and the F(1,1)mode has great fault location advantage.(2)The location frequency band of 20~60 kHz reduces the interference of guided wave dispersion and environmental noise to GIL sound source localization,which helps to improve the accuracy of fault location.(3)The GIL non-straight pipe structure will cause a large amplitude attenuation and a certain degree of time delay to the F(1,1)mode.Considering the influence of the attenuation and time delay of the GIL non-straight pipe structure in fault location can make the positioning error is further reduced by more than 60%.