Preliminary Study on the Human Body Electric Shock Criterion Based on FFT and Cubic Hermite Interpolation

doi:10.11985/2023.01.015

Abstract

Abstract:

To address the current situation that residual current protection equipment on transmission lines of low-voltage distribution networks based on TT systems(protection systems where the metal enclosures of electrical equipment are directly grounded) cannot guarantee immediate action after human electrocution, firstly, the in vivo electrocution experiment platform is built, and the electrocution experiment is conducted on the pig epidermis through the power supply with single-phase voltage RMS 220 V and frequency 50 Hz, and the relationship between the electrocution waveform and the electrocution area, the electrocution humidity and the leakage current magnitude at the time of electrocution is studied using the method of control variables to obtain the experimental data; secondly, the experimental data are processed, and the harmonic distortion rate at the moment of touching is calculated using FFT, and the touching waveform envelope is plotted using the cubic Hermite interpolation algorithm to calculate the slope of the envelope at different moments. Finally, the minimum value of harmonic distortion rate and suitable slope are selected, and the simulation platform is built to simulate the human body impedance obtained by fitting the experimental data, and the changes of harmonic distortion rate and peak slope of waveform are used as the basis for judging the electrocution of residual current protection equipment. The feasibility of the proposed criterion is verified.

Key words: TT system, electric shock test, dynamic impedance model, fast Fourier transform, cubic Hermite interpolation

CLC Number:

TM561

WANG Xinyang, WEI Yunbing, XU Hao. Preliminary Study on the Human Body Electric Shock Criterion Based on FFT and Cubic Hermite Interpolation[J]. Journal of Electrical Engineering, 2023, 18(1): 133-142.

Figures/Tables 24

References 20

[1]	姚天雨. 基于行为安全理论的生产安全触电事故原因归类和统计研究[J]. 工业安全与环保, 2021, 47(5):76-79.
	YAO Tianyu. Causes classification and statistical analysis on work safety electric shock accidents based on behavior-based safety theory[J]. Industrial Safety and Environmental Protection, 2021, 47(5):76-79.
[2]	白云, 余立平. 浅议配网工程管理安全风险管控[J]. 大科技, 2017(24):110-111.
	BAI Yun, YU Liping. A brief discussion on safety risk control of distribution network engineering management[J]. Super Science, 2017(24):110-111.
[3]	王序辰. 低压居民用户频繁停电原因分析与预防应对措施[J]. 农村电气化, 2021(2):16-18.
	WANG Xuchen. Analysis of the causes of frequent power outages and preventive countermeasures for low-voltage residential customers[J]. Rural Electrification, 2021(2):16-18.
[4]	李天友, 郭峰. 低压配电的触电保护技术及其发展[J]. 供用电, 2019, 36(12):2-8.
	LI Tianyou, GUO Feng. Electric shock protection technology and its development of low-voltage distribution[J]. Distribution and Utilization, 2019, 36(12):2-8.
[5]	李奎, 陆俭国, 武一, 等. 自适应漏电保护技术及其应用[J]. 电工技术学报, 2008(10):53-57.
	LI Kui, LU Jianguo, WU Yi, et al. Adaptive technology of leakage current operation protection and its application[J]. Transactions of China Electrotechnical Society, 2008(10):53-57.
[6]	周晓辉. 新农村供配电若干问题简析[J]. 建筑电气, 2020, 39(9):48-53.
	ZHOU Xiaohui. Brief analysis on some problems of power supply and distribution in new countryside[J]. Building Electricity, 2020, 39(9):48-53.
[7]	滕松林. 浅析一种新型触电漏电保护器[J]. 农村电气化, 1999(7):41.
	TENG Songlin. Analysis of a new type of electric shock leakage protector[J]. Rural Electrification, 1999(7):41.
[8]	潘永长, 李紫莲, 凌军, 等. 基于谐波特征的活体触电判据研究[J]. 浙江电力, 2021, 40(1):56-60.
	PAN Yongchang, LI Zilian, LING Jun, et al. Research on live electric shock criterion based on harmonic characteristics[J]. Zhejiang Electric Power, 2021, 40(1):56-60.
[9]	许冠炜, 郑荣进, 邓明在. 低压电网线性负载漏电流的特性分析[J]. 电气技术, 2021, 22(1):29-34,108.
	XU Guanwei, ZHENG Rongjin, DENG Mingzai. Characteristic analysis of linear load leakage current in low voltage power grid[J]. Electrical Engineering, 2021, 22(1):29-34,108.
[10]	陈航宇, 李天友, 杨智奇. 低压配网剩余电流保护运行现状及相关措施分析[J]. 电气技术, 2021, 22(1):104-108.
	CHEN Hangyu, LI Tianyou, YANG Zhiqi. Analysis of current operation status and relevant measures of low-voltage distribution network residual current protection[J]. Electrical Engineering, 2021, 22(1):104-108.
[11]	任龙霞. 活体触电识别研究[D]. 杭州: 浙江大学, 2012.
	REN Longxia. Research on electric shock in vivo[D]. Hangzhou: Zhejiang University, 2012.
[12]	祁才君, 陈隆道, 王小海. 应用插值FFT算法精确估计电网谐波参数[J]. 浙江大学学报, 2003, 37(1):112-116.
	QI Caijun, CHEN Longdao, WANG Xiaohai. High-accuracy estimation of electrical harmonic parameters by using the interpolated FFT algorithm[J]. Journal of Zhejiang University, 2003, 37(1):112-116.
[13]	甘辉, 詹丽萍, 廖丹敏. 基于FFT的电网质量检测关键技术仿真与实现[J]. 电脑知识与技术, 2020, 16(22):14-16.
	GAN Hui, ZHAN Liping, LIAO Danmin. Simulation and implementation of key technology for power network quality detection based on FFT[J]. Computer Knowledge and Technology, 2020, 16(22):14-16.
[14]	GUO Yun, XU Minhu, ZHANG Jian, et al. Research on grid high voltage harmonic detection based on ubiquitous power wireless network[J]. Journal of Physics:Conference Series, 2021, 1865(2):022028. doi: 10.1088/1742-6596/1865/2/022028
[15]	马锐, 贾学翠, 张永康, 等. 基于三次样条插值法的储能锂电池建模与参数辨识[J]. 电源学报, 2023, 21(1):133-141. doi: 10.13234/j.issn.2095-2805.2023.1.133
	MA Rui, JIA Xuecui, ZHANG Yongkang, et al. Modeling and parameter identification of Li-ion battery for energy storage based on cubic spline interpolation[J]. Journal of Power Supply, 2023, 21(1):133-141. doi: 10.13234/j.issn.2095-2805.2023.1.133
[16]	梁英, 贾丹丹, 李强, 等. 基于三次Hermite插值与线性规划的Lorenz曲线逼近方法[J]. 统计与决策, 2017(8):67-70.
	LIANG Ying, JIA Dandan, LI Qiang, et al. Lorenz curve approximation based on cubic Hermite interpolation and linear programming[J]. Statistics and Decision, 2017(8):67-70.
[17]	REKATSINAS C S, CHRYSOCHOIDIS N A, SARAVANOS D A. Investigation of critical delamination characteristics in composite plates combining cubic spline piezo-layerwise mechanics and time domain spectral finite elements[J]. Wave Motion, 2021, 106:102752. doi: 10.1016/j.wavemoti.2021.102752
[18]	李春兰, 叶豪, 王成斌, 等. 基于猪触电试验的人体触电规律研究[J]. 江苏大学学报, 2019, 40(5):553-558,565.
	LI Chunlan, YE Hao, WANG Chengbin, et al. Human electric shock law based on pig electric shock experiment[J]. Journal of Jiangsu University, 2019, 40(5):553-558,565.
[19]	中华人民共和国国家质量监督检验检疫总局, 中国国家标准化管理委员会.GB/T 13870. 1—2008 电流对人和家畜的效应第1部分:通用部分[S]. 北京: 中国标准出版社, 2008.
	General Administration of Quality Supervision,Inspection and Quarantine of the People’s Republic of China,Standardization Administration of the People’s Republic of China. GB/T 13870. 1—2008 Effects of current on human beings and livestock—Part 1:General aspects[S]. Beijing: Standards Press of China, 2008.
[20]	张前领, 马飞, 申翔. 鉴相鉴幅漏电保护器的应用[J]. 科学与财富, 2017(27):246-246.
	ZHANG Qianling, MA Fei, SHEN Xiang. Application of phase and amplitude leakage protectors[J]. Science and Wealth, 2017(27):246-246.

限制电流/mA	触电面积/cm²	谐波畸变率(%)
限制电流/mA	触电面积/cm²	干燥情况	半湿润情况	湿润情况
30	0.5	5.49	25.72	83.33
100	0.5	71.52	16.49	15.48
300	0.5	18.97	41.93	49.97
500	0.5	15.07	10.16	68.93
30	5	154.52	43.46	9.81
100	5	14.65	44.26	33.83
300	5	11.25	100.01	75.15
500	5	138.52	39.60	66.10
30	10	30.28	16.66	9.81
100	10	43.67	137.77	93.29
300	10	43.60	44.78	340.09
500	10	51.63	5.75	243.47

限制电流/mA	触电面积/cm²	干燥情况		半湿润情况		湿润情况
限制电流/mA	触电面积/cm²	斜率1	斜率2	斜率1	斜率2	斜率1	斜率2
30	0.5	0.359 6	0.251 6	0.201 0	0.242 5	1.057 2	0.107 8
100	0.5	0.822 4	0.066 5	1.348 3	1.183 2	2.293 1	1.150 0
300	0.5	2.719 1	3.024 2	7.879 3	2.576 9	4.399 4	4.400 8
500	0.5	4.227 9	4.859 3	13.647 5	3.510 7	7.407 5	3.521 4
30	5	0.451 3	0.113 2	0.134 9	0.052 3	0.748 7	0.056 0
100	5	2.705 3	2.075 6	0.949 1	0.566 9	1.424 0	0.303 1
300	5	2.297 6	2.096 4	2.485 9	0.924 1	2.666 2	0.811 4
500	5	5.655 8	1.561 7	9.334 0	3.501 8	10.530 0	0.994 8
30	10	0.650 2	0.328 1	0.650 2	0.075 1	0.748 7	0.013 2
100	10	3.103 5	1.653 2	1.575 0	0.538 1	2.313 9	0.227 3
300	10	7.746 3	2.126 5	8.286 2	6.976 5	11.152 0	6.153 8
500	10	7.087 8	5.018 6	9.457 8	4.604 1	16.395 0	4.920 2

仿真模块参数	数值
三相电源线电压/V	10 000
三相电源容量/(V·A)	100 000
频率/Hz	50
变压器变比/(一次/二次)	10 000/400
变压器绕线方式	DYn11
线路电阻/(Ω/km)	0.012 73
线路电感/(H/km)	0.933 7×10^-3
线路电容/(F/km)	12.73×10^-9
负载功率/W	30 000
故障开关通断时间/s	0.08~0.22
人体阻抗并联电容/F	2.2×10^-7

判据	特点
文献[8]双重触电判据	能够实时计算THD，并通过THD和电流整定值判断人体触电，但会造成误判，导致误动
文献[20]JD6型漏电保护器判据	能够计算各半周波幅值幅度变化大小，并通过幅度大小判断人体触电，但仅通过幅值幅度变化判断，灵敏度低，容易造成拒动或误动
本文判据	能够实时计算THD，判断人体触电开始时刻，并通过计算各周波间的变化来进一步判断是否是人体触电，增加了可靠性和灵敏度