Research On The Joint Detection And Location Method Of High-resistance Fault In Distribution Network

In recent years,with the continuous improvement of people's living standard,the contradiction between supply and demand of electricity is increasingly prominent,and people have put forward more stringent requirements on power quality and power supply reliability.In order to further improve the power supply reliability,a series of problems such as fault detection and location of distribution network have attracted people's attention.Due to its features of variable topology and weak power frequency signal,the detection and location problems of distribution network are always difficult to overcome,and the research is usually limited to the most common single-phase metallic grounding fault.In contrast,the high-resistance fault has been neglected in the past because it does not cause direct harm to the stable operation of the system due to its long-term existence.Nowadays,people pay more and more attention to the construction of distribution network,especially to prevent the occurrence of such hidden faults.Considering that the power frequency signal of high resistance fault in distribution network is very weak and the characteristics of nonlinear grounding,it is urgent to strengthen the research on the detection and positioning of high resistance fault in distribution network.This paper firstly analyzes the fault characteristics of single phase high resistance ground fault under distribution network failover,and based on this,a quick start method for distribution network high resistance fault is proposed using the zero-sequence current gradient,so unbalanced load and ground fault can be distinguished effectively.Based on the voltage injection caused by the fault phase transfer,the paper puts forward a line selection method applicable to high resistance ground faults in distribution network,using the polarity difference of transient feature and amplitude difference of steady state feature between fault traveling wave caused by single phase arc ground fault and closing traveling wave generated in the process of fault phase transfer grounding,to get accurate and reliable results of line selection.This method overcomes the shortcomings of line selection methods using single steady and ordinary transient signal.A phase selection criterion driven by phase current gradient for high resistance faults of distribution network is presented to improve the accuracy of failover arc extinguishing device.Secondly,a single phase ground fault location method for a mixed feeder based on characteristic distribution of traveling wave along a line is proposed by combining a morphological spectrum-based fault-section identification technique with a fault location method based on characteristic distribution of traveling wave along a line.Simulation results show that the proposed method is flexible and effective under different fault conditions,and can reliably solve the problem of identifying fault segments and reflecting waves at fault points in single-end positioning of hybrid distribution lines.Finally,on the basis of the theory of characteristic distribution of traveling wave along a line above,a method of high resistance fault active-passive location based on voltage injection caused by the fault phase transfer is proposed for radial multi-branch mixed distribution network.This method combines a morphological spectrum-based fault cut set recognition algorithm with a fault location method based on characteristic distribution of traveling wave along a line.And the final fault location can be obtained by synthesizing twice location results using traveling wave and failover closing traveling wave.It is proved that under different high value transition resistances and fault initial angles,all fault errors are within a reasonable range.