Effect of voltage flicker on leakage current in mine electrical networks containing power electronic devices

Purpose. To build a mathematical and simulation model to evaluate the effect of voltage flicker on leakage current in an underground mine AC power network containing power electronic devices. Methodology. The research methods used in this study include theoretical method to build the equation of leakage current and simulation modeling method on Matlab/Simulink software to determine the leakage current values in each case of voltage flicker. Findings. In addition to the theoretical analysis on the mine power network model, the paper also evaluates the mine power network model containing the converter on Matlab/Simulink with the model parameters U = 1,140 V, C = 0.19 uF/phase, R = 168 k/phase. The research results show that in the case of low voltage flicker with voltage amplitude lower than 50 % of rated voltage in ½ network cycle, the leakage current before the inverter decreases by the largest 19.7 % and the leakage current after the inverter decreases by the largest 5.2 % compared to the leakage current value at normal voltage. In the case of overvoltage flicker with voltage amplitude higher than 150 % of rated voltage in ½ network cycle, the maximum leakage current before the inverter increases by 33.6 %, the maximum leakage current after the inverter increases by 47.4 % compared to the leakage current value at normal voltage. This problem causes the phenomenon of mistaken operation of the leakage protection relay and causes unsafety in mining. Originality. The study includes the introduction of a leakage current model in an underground mine’s AC power network containing power electronic devices and the simulation to find out the influence of voltage flicker on the leakage current in that power network using Matlab/Simulink software. Practical value. The research results indicate the need for measures to minimize voltage flicker, thereby improving the reliability of leakage protection and improving safety in mining.