Research On Fault Warning And Localization Of Cable Terminations And Its Software Development

With the development of Electric utilities,user's demand for power energy has increased dramatically.Recent years,the coverage area of distribution network in our country has tended to enlarge,the line has been more complicated,and the power supply ability has tended to be stable.The consequent failure problems seriously affect the power increase level.The fault of distribution network in our country is mainly single phase to ground.The short circuit current of single phase grounding can only be formed by the small current loop through the line to ground capacitance.The weak signal causes the recognition difficulty.Because of more and more complex distribution network,the location of the fault occurs more difficult.This seriously affects the reliability and economy of power supply,and has become an important issue concerned by the current power research.In this dissertation,the signal change of single phase to ground fault in radial distribution network is analyzed and the fault feature is studied.Based on the characteristic that the transient signal is much larger than the steady signal,we first analyze the transient zero sequence current of the first terminal of each branch by using the wavelet analysis modulus maximum theory,then the fault section is found by the method of the relative entropy of the wavelet packet energy spectrum in the current signal of each node on the fault line.According to these researches,the fault can be located successfully,which provides a theoretical basis for the rapid monitoring and troubleshooting.We establish the distribution line fault model through MATLAB/SIMULINK,and the accuracy of the fault location method is verified by simulation.In this dissertation,a fault locating and positioning software for medium voltage cable terminals is developed.The software can monitor the short circuitgrounding fault at the corresponding line node with acquisition device.At the same time,the software can monitor the temperature overrunning,ground fault,zero sequence current and so on when the cable line node is in operation,and locate the fault zone in time accurately.So it can quickly troubleshoot and restore line power supply.