Citation: Lu, H.; Chen, J.; Li, G.; Xu,
K.; Tan, B.; Tong, X.; Teng, Y.; Li, C.;
Lan, L.; Wen, X. Current Density
Limit of DC Grounding Facilities
Considering Impact on Zebrafish
(Brachydanio rerio). Sustainability 2022,
14, 3942. https://doi.org/10.3390/
su14073942
Academic Editors: João Carlos de
Oliveira Matias and Paolo Renna
Received: 8 October 2021
Accepted: 21 March 2022
Published: 26 March 2022
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Article
Current Density Limit of DC Grounding Facilities Considering
Impact on Zebrafish (Brachydanio rerio)
Hailiang Lu
1,
* , Jiahao Chen
1
, Guanhua Li
2
, Kai Xu
2
, Bo Tan
3
, Xuefang Tong
3
, Yun Teng
1
, Chun Li
1
, Lei Lan
1
and Xishan Wen
1
1
School of Electrical Engineering and Automation, Wuhan University, Wuhan 430072, China;
kevinchan0811@gmail.com (J.C.); clara_yun@whu.edu.cn (Y.T.); lichun_jz@whu.edu.cn (C.L.);
leilan69@163.com (L.L.); xswen@whu.edu.cn (X.W.)
2
State Grid Liaoning Electrical Power Company Limited, Shenyang 110000, China;
18624006262@126.com (G.L.); 13591985462@163.com (K.X.)
3
China Electric Power Research Institute, Wuhan 430072, China; tolbotan@163.com (B.T.);
tongxuefang@epri.sgcc.com.cn (X.T.)
* Correspondence: luhailiang@whu.edu.cn
Abstract:
Grounding facilities, including high-voltage DC grounding electrodes and auxiliary anodes
in impressed current cathodic protection systems, inject current into the ground. This study developed
an experimental platform to determine the safe limit of current density for such facilities through
an analysis of fish behavior on the platform. Zebrafish (Brachydanio rerio) were selected for the
experiment and placed in a tank; two rod electrodes were used to inject direct current into the water.
A wireless camera was focused on the water tank to video record possible changes in fish behavior.
The output voltage of the DC power source was varied, and the trajectories of the fish under various
direct current fields were recorded. A tracking program was developed to analyze the trajectories
and quantify the behavior of the fish. A new method combining the trajectories of fish samples with
the results of current density calculations for analysis was proposed. Results demonstrated that the
zebrafish could sense current in the water and turn when exposed to certain current densities. The
intensity of the current at the turning points was statistically analyzed, and the threshold of current
density at which the fish could no longer tolerate the current and turned was 0.4231 A/m
2
.
Keywords:
underground current; fish behavior; target recognition and tracking; HVDC grounding;
current density
1. Introduction
Direct current grounding facilities have become increasingly common due to the rise in
the construction of industrial projects. An essential aspect of these projects is the application
of high-voltage direct current (HVDC) grounding electrodes. They work under either a
bipolar symmetrical mode or a monopolar mode. When HVDC grounding electrodes
operate under a monopolar mode, the transmission system uses the ground as a return
path for the current, and an extremely high operating current is injected into the ground [
1
].
In addition to HVDC grounding electrodes, sources of underground direct current include
impressed current cathodic protection systems [
2
] and traction power systems in urban rail
transit [3,4].
Both grounding electrodes and auxiliary anodes are constructed directly in the ground,
and the current they release into the earth may affect the surrounding fauna, especially fish
in nearby rivers or ponds. Because water has higher conductivity than soil does, the current
passing through may be larger and may thus affect the lives of fish. Several scholars have
studied the effects of electromagnetic fields on fish. Some of them have focused on electric
fishing because it has become widely practiced over the past century, and some [
5
–
7
]
have focused on electric anesthesia. Others have focused on the electromagnetic effects
Sustainability 2022, 14, 3942. https://doi.org/10.3390/su14073942 https://www.mdpi.com/journal/sustainability
