Research On Fault Location Method For Single-phase Grounding Fault In Resonant Grounding Distribution Network

The structure of distribution network is complex and has many branches,which often contains a large number of overhead transmission lines and cable lines.Its environment is relatively bad,and it has a high fault rate in the power system,most of which are single-phase grounding fault.The quick and accurate location of the fault area can reduce the burden of line inspection and shorten the time of fault repair,which is significance to ensure safe and reliable power supply.At present,non-solidly grounding system is widely used in the distribution network of China.Due to the effect of arc suppression coil,the characteristics of the resonant grounding distribution network are not obvious,and it is difficult to locate the fault points when high resistance grounding and arc grounding faults occur.Therefore,this paper focuses on the single-phase grounding fault location technology in resonant grounding distribution network and the following research work is carried out:1.In order to solve the problem of feeder section location in resonant grounding system with single-phase grounding fault,a mathematical model for single-phase grounding fault analysis in resonant grounding distribution network was established.The fault characteristics of ground fault transient process are analyzed based on the model.The analysis results show that under different transition resistances,the attenuation characteristics of the zero-sequence current transient components of the upstream and downstream transmission lines of the fault point are different,and a fault section location method based on the difference of zerosequence characteristic was proposed.The electromagnetic transient fault simulation model of 10 k V resonant grounding distribution network is built by PSCAD / EMTDC.The simulation results show that the proposed fault section location method has a strong adaptability to withstand the transition resistance,achieves accurate section location effect under different transition resistance and arc grounding fault,and it is not affected by the initial phase angle of the fault.2.In order to realize the zero sequence characteristic fault section location method proposed in this paper,the fault location terminal with high sampling frequency,4G communication and synchronous sampling is designed and developed.A 10 k V resonant grounding system model was built in the Intelligent Distribution Network Laboratory of China Southern Power Grid Research Institute,and a physical dynamic simulation experiment was carried out on the terminal.The dynamic mode test results verify the capability of information acquisition,processing and location of the developed terminal,and the effectiveness of the proposed method based on zero-sequence characteristic for single-phase grounding fault location of resonant grounding distribution network.3.The zero-sequence voltage distribution characteristics of hybrid transmission lines and three-terminal transmission lines are analyzed.Based on the double-ended synchronous time domain location method,a mathematic observation model for single phase grounding fault line identification and fault location is established,which is suitable for hybrid transmission lines and three-terminal transmission lines,and particle swarm optimization algorithm is used to quickly search and solve the optimization equation.The PSCAD/EMTDC electromagnetic transient simulation model is used to simulate and test the proposed method,the results show that the proposed fault location method has high accuracy and stability under different fault positions,fault initial phase angles,transition resistances and arc grounding fault.