Arc Ground Fault Detection And Early Fault Identification In Distribution Network

The detection and protection actions of distribution network faults are of great significance.Over the past years,many scholars have focused on rapid fault detection,fault location,and line selection protection actions,make a great contribution to the safe and reliable operation of the distribution network,but the understanding of arc ground faults and early faults is not enough.Nowadays,it is possible to use the existing technology to better extract the fault information of the distribution network,and to further study the arc ground fault detection and early fault identification of the distribution network,which is of great significance for the risk assessment and stable operation of the distribution network.Firstly,the theoretical model of arc is briefly analyzed.In the past,scholars have regarded arc fault as a switch simulation.Although this can meet the requirements of distribution network line selection and fault location,it has great interference in analyzing the actual development process of faults and detecting faults.In this paper,from the study of arc micro characteristics,the arc gap energy balance theory is used to build the arc fault model of the distribution network,and the change of arc power dissipation and the scene of the fault are considered.Secondly,PSCAD is used to simulate and analyze the different types of arc faults in the distribution network.According to the theory of thermal breakdown and electrical breakdown,arc faults are divided into two types: stable and unstable.For stable arc faults,the waveform distortion of the fault phase voltage is used.The proportion of harmonic components to determine whether an arc fault occurs.For unstable arc faults,multiple mutations of zero-sequence current,"zero rest period" and multiple mutations of zero-sequence energy are used to form a detection method.The arc fault scenes are divided into the cabinet body and the outdoor.Through the high voltage AC arc test,the arc characteristic spectrum is obtained in the ultraviolet and visible light bands.For the arc fault in the cabinet body,due to the high hazard,the photoelectric integrated detection method is adopted.Finally,according to the content of the early failure in the supplementary part.The identification of early faults focuses on overhead distribution lines with frequent faults,and mainly focuses on fault causes,hidden faults,and fault development characteristics.Regarding the inducement,it is introduced that overvoltage is the main cause of the distribution network failure.According to the test and operating experience,it is difficult for the power frequency voltage to cause the insulation breakdown to cause the failure.Therefore,this article also discusses the lightning induced overvoltage and common operations of the distribution network.Over-voltage simulation analysis,based on the difference in frequency band distribution of zero-sequence current of simulated and measured data,determine whether the cause of the fault is lightning.In the context of a transparent power grid,the mechanism of hidden faults in the distribution network is analyzed,and high-resistance ground faults are mainly studied.Aiming at the development characteristics of the fault,the arc grounding fault is studied,and its extinguishing stage is divided into the transient process and the steady state process,and the zero-sequence volt-ampere curve is used to judge the development trend of the arc fault.For high-resistance grounding faults under ineffective grounding,arc series resistance is used for modeling and simulation analysis,and high-resistance grounding faults in the distribution network are identified by means of active and passive joint detection.