Study On Faulted Line Detection Based On Transient And Steady Characteristics And Adaptive Protection

Non-effective grounded mode improves reliability of power supply significantly,security for devices and workers and reduces electromagnetic interferences tocommunication system. But insulation of power system is damaged by run with faultsfor long time, especially when intermittent arcing grounded fault events occurs.Over-voltage is most likely to cause the extension of fault events for other groundedpoints, meanwhile, fault current is probable to result in phase-to-phase fault. Reversepolarity connection of TV and TA results in line selection error based on comparisonof polarity and direction in practical applications. So study on line selectiondependently of polarity of TV and TA improves line selection reliability and accuracy,decides severity of fault and insulates faults if necessary.Thesis analyzed reverse connection TV and TA and its impact of polaritycomparison of transient current and direction of reactive power. Transient and steadycharacteristics are considered after single phase earth fault event in resonant groundedsystem, a novel line selection procedure is proposed based on transient and steadycharacteristics. A procedure is proposed for adaptive grounded fault protection inneutral point non-effectively grounded system. Suppose reliability of line selection ishigh, some factors are considered, type and insulation condition of transmission line,severity of fault events and power supply reliability demand for loads. Thenreasonable fault line selection decides whether or when to trip based on factorsmentioned above. Adaptive trip realization is designed. Reliability of line selection isverified by simulation and data on site, adaptive protection procedure proposed istested by data on site.The proposed procedure makes up defects of line selection failure for reverseconnection of TV and TA. Simulation analysis and data on site verified accuracy and practicality. Adaptive tripping protection retains advantages of run with faults andavoids over-voltage in non-effective grounded systems, meanwhile reliability andsecurity of power supply is considered. Test on site verified reasonable and necessityof adaptive protection procedure.