Research On Fault Location Of Transmission Line Based On Single-ended Transient Travelling Waves

In recent years,with the continuous expanding of the scale of power network,the topology of high voltage transmission line becoming complicated,the lines increasing,causing the probability of transmission line fault is more and more big.In order to avoid widespread blackouts caused by transmission line fault,we must take measures.When the line failure,how to find fault and troubleshoot quickly,which is of significance for the safe and stable of the power system.Seeking a effective method of fault location has become a hot spot of current research.Single-ended traveling wave fault location method is widely applied to fault diagnosis of transmission lines because of its reliability and accuracy.Meanwhile,it is not influenced by line type,fault resistance and the systems theoretically.However,the traditional fault location method generally does not consider the uncertainty of traveling wave speed and influence of current transformer’s transmission circuit,this thesis proposes a fault location method with four-partitions and wavelet scale transformation,which mainly completes the following aspects:Through the research on the detection method of Fourier analysis,Hilbert-Huang transform and wavelet transform,we know the advantages and disadvantages of the three methods.And we carried out traveling wave detection simulation by the three methods mentioned above,the simulation results shoe that the wavelet transform is the best method to realize the traveling wave.Based on the traveling wave polarity combination theory,a fault location method which is not affected by the wave speed is proposed based on the four-fault-partition method.The method mainly consists of three parts:four-fault-partition method,polarity combination of traveling wave,fault location.First of all,dividing each fault interval according to the categories of traveling wave traveling wave reflection and refraction principle;secondly,using wavelet modulus maxima method in-depth analysis of fault traveling wave,traveling wave polarity difference based on judgment as the location of the fault interval;finally,according to the fault interval formula verify fault distance.The method is not affected by the wave speed.In view of the traditional fault distance method is usually not considered effect of traveling wave speed and current transformer transmission circuit,the accuracy of fault location is low.Firstly,we research on current transformer circuit and propose a method of filtering the interference wave based on wavelet scale,which improves the accuracy of fault location.Meanwhile,we propose a adaptive fault location method to avoid the disadvantages of traveling wave method and impedance method,improving the accuracy of the fault location.