Study On Traveling Wave Propagation Characteristics And Fault Location Method Of Distribution Network In Engineering Environment

With the rapid development of the national economy,the structure of distribution network is becoming more and more complex,and load density is continuously increasing.The safe and stable operation of distribution network is especially important to ensure the reliable supply of electricity.Distribution network fault accounted for a large proportion in the entire power system fault,and there is an increasing trend year by year,so the precise fault location of distribution lines is of great significance for the quick recovery of power supply.The traditional fault location methods are not able to meet the accuracy requirements of fault location,which increases the difficulty of maintenance and extends the power outage time,so traveling wave fault location method has been paid much attention and widely studied.At present,traveling wave fault location of distribution network is usually a direct reference to the location method of transmission line.At present,traveling wave fault location of distribution network is usually a direct reference to the location method of transmission line.The consideration of actual engineering environment for distribution network is insufficient,related analysis is simplistic.For example,not taking full account of the complicated situation that distribution network has many branches,overhead lines,cable lines and hybrid lines coexist and substation bus hangs various compensation equipment.Thus,the accurate analysis of the transient characteristics of fault traveling wave and the improvement of traveling wave fault location method have been affected.In this thesis,traveling wave propagation characteristics of distribution network are analyzed in close combination with the actual engineering environment,and fault location method for networked distribution lines is studied.First,in accordance with the actual engineering conditions of substation and the typical structure of distribution line,the simulation model of distribution network is built and the transient characteristics of fault traveling wave are studied.According to the frequency characteristics of overhead line parameters,the influence of fault distance,transition resistance and fault phase angle on the transient characteristics of modal traveling wave are analyzed.Moreover,the propagation characteristics of fault traveling wave under different bus configurations are also analyzed by the reflection law of traveling wave,which are verified by simulation test.On the basis of these results,the propagation characteristics of modal traveling wave for cable are simulated.Then,based on the concept of wavelet transform,the relationship between the mutation point of signal and the modulus maxima is discussed.According to the characteristics of modal initial traveling wave,the selection principle of the wavelet function and the scale factor is determined.The influence of Gaussian white noise on the traveling wave singularity detection is analyzed.In the light of the wavelet transform results of linear mode and zero mode components,an improved algorithm for traveling wave singularity detection is proposed,which can effectively extract the arrival time of initial traveling wave under white noise interference.Finally,the comprehensive strategy of traveling wave fault location for complex distribution network with overhead,cable and hybrid lines is studied.According to the propagation characteristics of fault traveling wave under different line structures,the principle of selecting the voltage or current traveling wave as fault location signal is determined.Aiming at improving the accuracy of fault location,the layout scheme of traveling wave detection elements of each type of distribution lines is discussed,and the network method is used to correct the results of fault location.In the foundation of the above research,a comprehensive strategy of traveling wave fault location for complex distribution network is proposed,and the simulation results attained by the typical distribution network model verify its validity and practicability.