摘要
针对剩余电流保护装置因保护死区造成的投运率低和误动作问题,构建生物体的电学模型,获取大量的触电信号,进一步研究触电电流与剩余电流间的相互关系,可为解决保护装置存在的上述问题奠定基础。该文以猪为研究对象,采用Otsu算法将CCD相机采集的标准图像二值化,利用Canny边缘检测法提取图像轮廓并细化,在对图像归一化处理的基础上采用圆弧拟合法获取猪体轮廓关键点,并运用整体变换法获得猪体514个关键点的三维空间坐标,在ANSYS平台上建立猪的三维实体模型;基于修正系数法研究猪体组织介电特性的基础上,构建猪的电学模型并进行触电仿真试验。结果表明:触电电压相同时,面接触触电方式,左前肢-左后肢和左前肢-右后肢触电路径下平均电流密度分别为0.973和0.641 A/m^2,线接触触电时分别为0.782和0.579 A/m^2;相同触电方式下,左前肢-左后肢触电路径中的电流密度大于左前肢-右后肢触电路径中的电流密度,相同触电路径下,面接触触电方式触电电流密度大于线接触触电的电流密度;2种触电方式下各30组数据,触电仿真电流与触电物理试验获得电流的平均相对误差为3.5%,该电学模型在生物体触电仿真研究中可行。研究结果可为进一步研究人体电学模型提供参考。
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.
作者
李春兰
王海杨
张亚飞
杜松怀
叶豪
高阁
罗杰
Li Chunlan;Wang Haiyang;Zhang Yafei;Du Songhuai;Ye Hao;Gao Ge;Luo Jie(College of Mechanical and Electrical Engineering,Xinjiang Agricultural University,Urumqi 830052,China;College of Information and Electrical Engineering,China Agricultural University,Beijing 100083,China)
出处
《农业工程学报》
EI
CAS
CSCD
北大核心
2019年第20期185-193,共9页
Transactions of the Chinese Society of Agricultural Engineering
基金
国家自然科学基金资助项目(51467021)
关键词
有限元法
仿真
介电特性
Canny边缘检测法
圆弧拟合法
电学模型
电流密度
finite element method
simulation
dielectric property
Canny edge detection method
arc fitting method
electrical model
current density