Leakage protection scheme of coal mine low voltage distribution network based on parameter identification

Due to the small fault current and unstable arc, the fault location problem of low power coal mine phase-to-ground fault has not got thoroughly solved. The existed leakage judging method of coal mine low voltage distribution network has the disadvantages of large error and long action time, so it is unfavorable for safety operation. This paper give a new methods which based on the model parameter identification to the location problem of low power coal mine, establish the mathematical model of each line´s external fault, use the zero sequence voltage and current to estimate model parameters in the least-square method, judge whether did the actual fault conform to the model by the line´s capacitance c and insulation resistance r, and further identify the fault lines and use the method of additional DC source to be a protective device of back-up protection. In the end introduced the hardware diagram and software flow of the protection device which selects the leakage based on this method. This method is not affected by the factors of leakage resistance, leakage angle, leakage location, and have the ability of anti-noise interference.