The Single-phase Ground Fault Research Of Well Supply Network In Small Current Grounding System

China’s distribution network is generally small current grounding system, most of theneutral grounding are ungrounded or suppression coil grounding system. The incidence ofsingle-phase ground fault is biggest in failures of the power system, and after a fault, lineselection accuracy will be affected by many external factors. So the single-phase ground faultline selection is worthy for further study and explore.Firstly, the author analysis and study the principle of single-phase ground fault, also withline selection method in small current grounding system, elaborate the transient andsteady-state characteristics of the system when a fault occurs. According to the situation ofDaqing Oilfield grid, power lines from the substation to the oil well are so many that whensingle-phase ground fault occurs, the staffs depend mainly on the way of line-by-line wind upto detect the fault, this method can not find the fault line timely. When single-phase groundfault occurs in single-supply of electricity radial networks, the negative sequence currentphase angle difference in fault line and non-fault line tend to be180degrees, based on thenegative sequence current characteristics of the grid the author proposed the negativesequence current method of line selection. Because of the need to determine is only the phaseangle of the negative sequence current, so this selection method is convenient and easy. Andthe author verifies the correctness and validity of the method by a large number of simulations.The location of oil well is generally more remote, and that the grid transmission line is longer.Then he studies the characteristics of Zigbee wireless communication technology, just likepower consumption, latency, high reliability and so on. These characteristics are suitable forusing Zigbee in the oil field power system grid for data acquisition. After using Zigbee totransmit and aggregate data, the host computer uses the VB technology for data processing.The author combines negative sequence line selection method with the fifth harmonic methodto writes the fault line selection procedures, and also builds the intuitive PC display interface.