Research Of Transient Characteristic After Opening Single-Phase Earth Fault On UHV Transmission Line

The ultra-high-voltage (UHV) transmission system takes an important part in China electrical power development. The issue of insulation becomes more and more outstanding with the increase voltage classification. The restriction of overvoltages and the proper selection of insulation coordinations are the key subject in UHV transmission engineering construction. Therefore the research on overvoltage and adaptive auto-reclosing technique for UHV transmission line is of great practical significance.The paper focuses on the transient characteristics of single-phase earth fault on UHV transmission line. Several aspects of overvoltage are studied in-depth on UHV power grid, including transient recovery voltage, line induced voltage, extinction characteristic of secondary arc. Several research aspects as the following:According to structural characteristics of the actual line and interal structure of GIS to set up the simulation model of the whole system. The paper first analyzes the effect electrostatic induction and electromagnetic induction on the transient recovery voltage, and conducts a detailed theoretical derivation. The paper simulates and analyzes transient recovery voltage under different fault types and different fault locations, and transient recovery voltage parameters changes after considering the effect of induced voltage. Analysis showed the induced voltage can increase the peak of transient recovery voltage, which bring forward higher requirements for the circuit breaker insulation level and provide theoretical basis for structural design of circuit breaker.The paper adopts frequency related parameter model on the transmission of UHV to analyze the physical process secondary arc and carry on the detailed theoretical derivation of the secondary arc parameters, and analyze the variation regularity of recovery voltage and secondary arc current, analyzes the mathematical models of the primary arc and the secondary arc under the temporary single-pole fault, and establishes the simulation models of arc. The computation results in this paper are testified by theformer test results and the maturity results. It is feasible that the idea based on establishing arc model and circuit model, and the calculation result is reasonable.The paper simulates and studies characteristic of secondary arc of the actual transmission line through establishing system model UHV demonstration project. The waveform of the voltage of faulty phase under the different type of fault is simulated by EMTP-ATP. Then, the voltage of faulty phase is transformed by the Fourier transform. In order to extract the key features which can be used to distinguish the type of fault, the transformation of the voltage of faulty phase in the period of secondary arc should be pay more attention to. Finally, training samples and the testing samples are obtained by lots of simulation, and single-pole adaptive reclosure based on transient component is realized by fuzzy neural network. The finally simulation results show that the method proposed in this paper of single-pole adaptive reclosure is correct and effective.