Construction and verification of 3D electrical model of pig body

At present, due to the complex nature and weather environment in the vast rural areas, protective devices of electricity has defects, and users' awareness of power safety is not strong, so electric shock accidents frequently happens. The wide application of residual current protection devices in low-voltage power grids can effectively prevent electric shock and fire accidents. However, the current setting value of the residual current protection device currently used is not directly related to the magnitude of the electric shock current. In the case of external disturbances and changes in the atmospheric environment at the installation site, the operation rate and correct operation rate of the residual current protection device in the rural power grid are far from meeting the actual requirements. Since the early 1980s, the hardware materials and control circuits of residual current protection devices have been continuously improved worldwide. However, there is little research on the detection and extraction of electric shock current, so the problem of residual current protection device is not solved fundamentally. In brief, in order to ensure personal safety and normal operation of the low-voltage power grid, it is necessary to develop a new residual current protection device based on the action of electric shock current. This requires a large number of electric shock signals to study the relationship between the electric shock current and the residual current. In this paper, the electrical model of the constructed organism was used instead of the physical electric shock test to obtain the electric shock signal. Because human specimens are difficult to obtain and are subject to ethical and moral constraints, the use of animals for electric shock tests to extract current and voltage signals can cost a lot in finance, material and manpower. On this basis, the research team established a model of pigs that was very similar to human anatomy, tissue and physiological characteristics, conducting an electric shock simulation experiment. Taking pigs as the research object, Otsu algorithm was adopted to binarize the standard images collected by CCD camera. Canny edge method was utilized to extract the image contour and refinement. On the basis of image normalization, arc fitting method was used to obtain the key points of contour, and global transformation method was used to obtain the 3d coordinates of 514 key points. The 3d solid model of pig was built by solid modeling method from bottom to top of point, line, surface and body on ANSYS platform. Based on the study of the relationship between dielectric properties of biological tissues and frequency, according to the dielectric properties of the main tissues of human in the whole frequency band and the known dielectric properties of the main tissues of pig in the high frequency band, the electrical parameters of the main tissues of pig in the low frequency band were obtained based on the correction coefficient method. By loading the electrical parameters of the main tissues on the three-dimensional solid model of pig, the electrical model of pig was constructed and the electric shock simulation experiment was carried out. The results showed that when the frequency was constant, the current density increased with the increase of the electric shock voltage. The relationship between electric shock current and frequency basically coincided with the current-frequency characteristic of CF Dalziel. When surface contact with electric shock, the average current density under the electric shock path of the left forelimb-left hind limb and left forelimb-right hind limb was 0.973 and 0.641 A/m2, respectively, and the line contact was 0.782 and 0.579 A/m2. When the electric shock voltage and the electric shock mode were the same respectively, the current density of the left forelimb-left hind limb contact circuit diameter was greater than that of the left forelimb-right hind limb contact circuit diameter. When the electric shock voltage and the electric shock path were the same respectively, the current density of the surface contact mode was greater than that of the line contact mode. There were 30 groups of data in each of the two electric shock methods. The average relative error between the simulated electric shock current and the obtained electric shock physical test current was 3.5%, the electrical model was feasible in the simulation study of biological electric shock. The research results can provide reference for further study of human electrical model.