Construction Of Pig Body Impedance Model And Experimental Verification Of Electric Shock

As a vital clean energy in the production and life of residents,electric energy promotes the progress of the world economy.Meanwhile,electric shock accidents often occur due to the leakage of transmission lines or improper operation of power equipment.With the large-scale use of the residual current protection device in the low-voltage distribution network,the electric shock accidents are reduced at certain extent.However,the operation practice shows that the current residual current protection device has the problem of misoperation or rejection operation in bad weather or heavy load input.In view of this,some scholars propose to develop a current separation protection device,but the key problem is the acquisition of electric shock signal.In this paper,pig body is taken as the research object,and the impedance model of pig body is constructed to obtain the electric shock signal by electric shock simulation experiment.The main research contents and conclusions are as follows:(1)The study and acquisition of the electric parameters of pig tissues at low frequency.According to the electrical parameters of human body tissues measured by Gabriel et al,a single-order Cole-Cole model of human body tissues is established based on the dispersion characteristics.Five characteristic parameters of the model are obtained by combining the Newton iteration method and the least square optimization technology.The electrical parameters of 12 main human tissues are further obtained.The average relative error between the calculated value of human body tissue electrical parameter model and the measured data of Gabriel is less than 6%,the results show that the biological parameters can be obtained at low frequency by constructed single-order Cole-Cole model.Considering that the dielectric properties of pig body and human body tissues are similar,a single-order Cole-Cole model of pig body tissue was constructed to obtaui the dielectric constant and conductivity of pig body tissue at low frequency.(2)The three-dimensional model of pig body was established based on the finite element method.The collected model pig body image was preprocessed,further the edge curve of pig body image was extracted and to be make smooth processing.The feature points of model pig body contour curve was extracted by combine the arc fitting method and dynamic planning algorithm.According to the basic idea of stereo vision,the three-dimensional spatial coordinates of the model pig body feature points was obtained,and transformed into the feature points of experimental pig body by the stretching transformation method.71 7 key points are defined by the method of finite element solid modeling.According to the anatomical structure of the pig body,the key points are connected into 466 smooth lines or curves by B-spline curve.Finally,266 surfaces are generated,and the three-dimensional solid model of the pig body is synthesized by Boolean operation.(3)Simulation analysis of three-dimensional electrical model of pig body.Under power frequency condition,36V voltage is applied to the three-dimensional electrical model of pig body to carry out electric shock simulation research.The current density distributed in pig body under the line contact mode is smaller than that under the surface contact mode,and the current density in the same-side electric shock channel is higher than that in the different-side electric shock channel.The change curve of the simulated electric shock current in the frequency range of 10～10000Hz is basically in accordance with the research results of CF Dalziel.Comparative analysis between 60 groups electric shock simulation results with pig’s electric shock physical test data,the results show that the established pig body electrical model has high reliability.(4)Construction and experimental verification of pig body impedance model.According to the heat obtained from the electric shock simulation of the pig body electrical model,combined with the Biegelmeier equivalent circuit model,the skin resistance and capacitance of the pig body based on Joule heat were respectively 719.83 Ω and 27.90 μF,and then the pig body impedance model was constructed.The electric shock experiment was carried out by the low voltage electric shock simulation system based on MATLAB platform and the established laboratory simulation electric shock experiment platform.The results show that in the second half of the electric shock,the simulation waveform of pig body impedance model fluctuates slightly compared with the signal waveform of pig body electric shock physical test,and the waveform curve is basically consistent after 0.05 s.The average relative error between the electric shock current obtained from the simulated electric shock experiment in laboratory and the electric shock current obtained from the physical electric shock experiment in pig is 3.8%,which verified the feasibility of pig body nmpedance model in acquiring electric shock signal.