Study Of Fault Location Method In Single-phase Grounding System

Power energy occupies a very important position in the national economic system of our country.With the rapid development of our national economy and industrial construction,the demand for electricity consumption is increasing,At the same time,distribution networks have gradually become more intensive.In the power system,due to the different operation mode,it will have an impact on the economy,security and reliability of the power system.Most of the medium-voltage distribution networks in our country adopt neutral point non-effective grounding system,which ensures the reliability of power supply through this grounding mode.But when the single-phase grounding fault occurs,the fault current is small,the electrical quantity is not obvious,the operation mode of the system is flexible and the structure of the line is more complex,which will cause certain obstacles to the accurate judgment of the fault point.So far,the problems mentioned above are still the difficult problems,which need to be solved urgently.At first,according to the difference between zero-sequence current values on both sides of the fault point,a single-phase grounding fault location method based on sample entropy is studied.The fault parameter is defined,that is,by obtaining the sample entropy of each point of the line,the maximum absolute value of the difference between the two adjacent detection points is the fault section.Then the simulation is carried out by electromagnetic transient software,the method is studied in two cases,respectively,the initial phase angle is fixed,grounding resistance changes and the grounding resistance is fixed,the initial phase angle changes.The feasibility of this method is verified through a large amount of experimental data.Secondly,according to the feature that high similarity of transient zero mode power on both sides of the single-phase grounding fault section,while low similarity of transient zero mode power on both sides of the non-fault section,a method of single-phase grounding fault location based on improved transient mode zero power correlation coefficient is studied.In this method,the power frequency zero mode power is introduced,which corrects district positioning misjudgement at the fault demarcation point and its vicinity due to polarity reverse connection of current transformer at detection point.Through a large number of simulation experimental data,this method has a wide range of application,furthermore,the neutral grounding method has little effect on it,which can improve the correct rate of positioning.