Identification Of EHV Line Single Phase Ground Fault

EHV transmission line faults are mainly single phase to ground faults, of which occurredvast majority are transient. The traditional reclosures cannot determine fault types beforereclosing which possibility results in blindfold reclosure of permanent fault. Therefore, it isnecessary to determine the fault type before reclosure. A new fault determining method has beraised based on the different components of recovery voltage to make up the disability oftraditional reclosures.Due to secondary arc as the major factor for the successful operation of reclosure, and itcan be restricted by shunt reactor and neutral reactor for HV shunt reactors.In this paper, therelation between value of shunt reactor and series resonance, the value range of neutral reactorfor HV shunt reactors are analyzed as the influence of different neutral reactors on secondaryarc current and recovery voltage, meanwhile, for the EHV transmission line with seriescapacitor, the influence of arc resistance on secondary arc current need to be analyzed andcalculated.Transient fault of recovery voltage with free component and frequency component andpermanent fault with only frequency component can be obtained by calculating the phase toearth fault of transmission line with shunt reactors on frequency domain, meanwhile, lowfrequency component also existed in transient fault and permanent fault for the EHVtransmission line with series capacitor. ESPEIT algorithm is used to evaluate each componentof fault phase voltage and to put forward different criterions for transmission line with shuntreactors and series capacitor.In this paper, circuit simulation model with shunt reactors and series capacitor has beenbuilt in ATP-EMTP to estimate recovery voltage of fault phase voltage by algorithm and thento validate criterions. A great many of simulations results proves that those criterions share a good results with high reliability and which has a remarkable potential in engineeringapplication for different fault types, noise-signal ratio as well compensation of shunt reactorsand series capacitor.