Research On Fault Diagnosis Of Distribution Network Based On Network Impulse Response

In China,most 10 kV distribution networks are small-current grounding systems.For this system,most of the faults are single-phase ground faults.For this kind of fault in the system,because the current is relatively small when the fault occurs,it will not affect the normal operation of the system,but once it is converted into a short-circuit fault,it will seriously endanger the normal operation of the system.Therefore,it is very important for the safe operation of the power grid to select the appropriate line selection and distance measurement method,find the exact fault point and remove the fault.Based on the research of the existing fault location method,this paper divides the fault location into two steps,adopts the impulse response method to select the fault line,and validates the correctness of the fault line selection based on the impulse response method in SIMULINK.Impulse response method is used to fault location.The accuracy of fault location by impulse response method is verified in PSCAD.For the problem of fault line selection,the steady-state and transient characteristics of single-phase grounding faults in the two different neutral grounding methods in the existing small-current grounding systems are compared and analyzed.Through analysis,it is found that single-phase grounding occurs.The zero-sequence voltage and the zero-sequence current have obvious changes in the transient process after the fault.On this basis,the impulse response method is proposed to be used for fault line selection.Through simulation and verification in SIMULINK,this method avoids the short time of transient components,difficulty in sampling,and the use of transient components.When the steady-state component selects the line,the zero-sequence current amplitude is small and the fault feature is insufficient,which has high accuracy and feasibility.For the problem of fault location,the principle of the impulse response method and the transmission characteristics of the impulse in the cable model are described in detail.At the same time,the selection of pulse waveform and parameters is introduced.The impulse response method is used in the 10 kV distribution network for faults.Ranging.A simulation model of 10 kV distribution network was built using PSCAD.The simulation was carried out under different fault conditions.The error signals before and after the fault were analyzed and compared.Through a large number of simulation examples,the fault distance and fault resistance influence the accuracy of the method.Very small,without the influence of distribution network topology,with high accuracy and feasibility.A large number of simulation examples show that the fault line selection method based on the impulse response method and the fault location method based on the impulse response method are accurate.