Study of leakage current in underground mine power network: a case study in mining in Vietnam

Abstract

Purpose. To determine DC leakage current in mine power network with long DC power transmission. Methodology. Nowadays, the increase in capacity and working depth leads to the use of DC power transmission, which has many benefits both economically and technically in mining. However, the appearance of DC power transmission changes the structure of the network. In the underground mine power network, there will be electrical networks with industrial frequency 50 Hz, DC power networks, and power networks after variable frequency inverters. The correlation of these network parameters complicates leakage protection in the mine power network. For DC power transmission in mining, the DC network parts have a large length, so during the working process, electricity leakage in these parts of the network often occurs. Leakage current in a DC network depends not only on DC network parameters but also on AC network parameters. The article uses analytical methods and simulation methods on Matlab/Simulink software to determine leakage currents in underground mine power networks with DC transmission when there is a change in power network parameters. Findings. The research results show that the leakage current value of the DC network is greatly affected when the insulation parameters of the electrical network change, not only in the DC power network but also in the AC network before and after the inverter. This causes the unreliable operation of the leakage protection device in this DC transmission network. Originality. Calculation model and simulation of DC leakage current in underground mine power networks with long DC transmission in mining in Vietnam Practical value. The research results are the basis for calculating and selecting leakage protection equipment for the purpose of improving safety in underground mining in Vietnam.