Affiliations: [a] State Key Laboratory of Power Transmission Equipment
and System Security and New Technology, School of Electrical Engineering,
Chongqing University, Chongqing, China | [b] Chongqing Electric Power College, Chongqing, China | [c] Chongqing Electric Power Research Institute, Chongqing, China
Correspondence:
[*]
Corresponding author: Fan Yang, State Key Laboratory of Power
Transmission Equipment and System Security and New Technology, School of
Electrical Engineering, Chongqing University, Chongqing, 400040, China. Tel.:
+86 23 65106977; E-mail: yangfancqu@gmail.com, hewei@cqu.edu.cn
Abstract: When the current distribution changes due to the breakage in the
grounding grid, the magnetic field in the vicinity of the grounding grid will
change, hence the magnetic field on the ground above the grounding can be used
to detect the breakage of the grounding. In the paper, the magnetic field
forward problem of the grounding grid is described firstly, and simulations
were carried out when the breakage was located at different position. Results
indicate that the maximum change of the magnetic flux density occurs at
different measuring point when the breakage was located at different position.
To achieve a more convenient method to detect the grounding grid fault, the
magnetic field inverse problem of the grounding grid is presented, which is the
process to calculate the current flowing in the grounding grid according to the
magnetic field strength, and the method based on the global regularization and
Damped Gauss-Newton method to solve the inverse problem is described, with
which the ill-posed and ill-conditioning characteristic of the inverse problem
can be diminished. Then the fault state of the grounding grid can be confirmed
in the following way. Firstly, inject a 10∼30A current
into the grounding grid, measure the magnetic field strength or the magnetic
flux density at the measuring points on the ground above the grounding grid,
then the current distribution can be obtained by solving the inverse problem.
If the parameters of the soil are known, the resistance distribution can be
obtained, with which the fault state of the grounding grid and the location of
the fault can be confirmed. An equivalent model to verify the inverse problem
was set up, and results indicate that the global regularization can diminish
the ill-posed and ill-conditioning characteristic of the inverse problem.
Keywords: Grounding grid, magnetic field, forward problem, inverse problem
