Study On Selective Of Short-circuit Protection Of Mine High Voltage Network Based On Traveling Wave Test

Nowadays the country's mine high-voltage power network with neutral not direct grounding are mainly consisted by multi-level radiation cable circuit, but the more difficult issue of the network consisted by cable is the selective of longitudinal over current protection. The breaker often operate with no choice when the short circuit fault occurred at the lower cable line, this is because the cable's resistance is smaller and the range of the instantaneous protection might become zero if adjust according to the normal, after adjust the setting value, the line of the lower short-circuit current value might exceed the higher breaker's instantaneous setting value and lead to the protection operate with no choice.The paper study the issue use the wavelet transform to analysis the fault traveling wave and by comparing the wavelet transform modulus'polarity and energy to accurately capture the time of the initial wave and the first reflected wave that come from the fault point arrival the protection installation, and according to the cable's characteristics using real-time on-line to measure the fault cable parameters to calculate the traveling wave's velocity, so as to determine the exact distance between the point of failure and the protection installation to achieve accurately fault location.Using the principle of selective and by computer's logical recognition technology to realize the selective operation of the cable's longitudinal over current protection, avoid information interactive among protections and improve the sensitively and reliability of the selective operate of the protection, and proving the way is correct by simulation.