The Study Of Single-phase-to-earth Fault Selection And Fault Location Based On The Model Parameter Identification Method In Non-grounded Neutral System

The non-effectively grounded system is used in the distribution net of 6-66kV. It has the virtue of proving power supply's reliability. But fault selection and fault location are not solved when single-phase permanent grounded fault appears. Through reviewing of the existing theories on fault line selection systematically, it points out the defects and drawbacks of those in this paper. It proposed a new approach to the single-phase-to-earth fault selection and fault location based on the model parameter identification method in the non-effectively neutral system.When single-phase earth-fault appears we establishes mathematical model of the zero sequence equivalence networks for every line under non-fault, then established corresponding differential equation on unknown variable of line parameters. The model parameter estimation of least square can be solved by the zero sequence voltage and the current of real-time gathered. According to the line zero sequence capacitance value to the ground and the zero sequence inductance from the fault point to the bus, the fault line can be selected and the location of fault can be measured. This principle has been verified via the EMTP simulator, and it is correct and reliable.We design a suit of equipment of fault line selection and fault location according to this project .The device's hardware and software is explained in detail.