756 / 2022-03-31 20:45:45

Conducting Impedance Analysis of Grounding Conductor

On-resistance, moment method, finite element method, sweep impedance

IEEE ICHVE 2022 / 1-PAGE ABSTRACT

Conducting Impedance Analysis of Grounding Conductor

WANG Yan,LI Huiqi,PAN Zhuohong,WANG Haocheng,TIAN Yang,GAO Lei

North China Electric Power University

1853715694@qq.com,huiqili@263.net,panzhuohong@ncepu.edu.cn,wanghaocheng814@163.com,2585824441@qq.com,GL1071947368@163.com

Purpose/Aim

The conductor impedance reflects the parameters and basic state of the grounding grid, so it is necessary to study the characteristics of the unit impedance of the substation grounding conductor. In order to solve the calculation problem of the conduction impedance of the irregular conductor section, the paper uses the method of moments and the finite element method to solve it. Conductor impedance characteristics are studied by simulating the current distribution on the conductor cross-section and considering the conductor's nonlinearity.

Experimental/Modeling methods

The conductors in the grounding grid of the power system generally use round steel. In the impedance calculation of the solid cylindrical conductor, it is found that there is a good agreement between the measured value of the AC resistance of the copper wire at 50 Hz and the calculation result of the theoretical formula. In the case of irregular conductor cross-section, the calculation and analysis of the conduction impedance can only be carried out by means of the numerical calculation method. The ground grid sweep conduction model can be established by using the HIFREQ module by the method of moments, and the nonlinear simulation of the steel conductor can be carried out by the finite element method calculate.

Results/discussion

The conductor impedance is calculated by the method of moments and the finite element method. The method of moments uses the HIFREQ module to establish a frequency sweep conduction model of the ground grid, and the electromagnetic field value can be obtained. The finite element method is used to calculate the conductor impedance, and the calculation result of the DC resistance is consistent with the theoretical formula. At the same time, the simulation calculation is carried out under the HIFREQ module, and the change curve of the conduction impedance with the frequency can be obtained. With the increase of the frequency, the AC impedance increases obviously. But currently the HIFREQ module is only suitable for linear problems, and nonlinear conductor materials are analyzed using finite element software.

Conclusions

The swept-frequency on-impedance was analyzed based on the method of moments, and the finite element method was used for simulation, the calculation results of the DC resistance and the swept-frequency results of the on-impedance were obtained. The results show that the calculated value of the DC resistance is consistent with the theoretical value, and the change curve of the on-resistance with frequency shows that the AC impedance shows an increasing trend with the increase of the frequency. The HIFREQ module is only available for linear materials, while the finite element method can be applied to swept-frequency impedance analysis of nonlinear materials.