Study On Fault Location Of County Distribution Network

With the development of economics and the progress of technology,the increasing demand of electricity has drawn a lot of attention on the dependence of electric energy.All social life and production activities put forward higher requirements on the reliability of power supply and the quality of electric energy.Therefore,the power supply department is required to improve the level of distribution automation.To locate,isolate and restore immediately from fault can reduce outage time when it occurs in distribution network.The research and application on rapid location of fault in distribution network play an important role on the improvement of the reliability of distribution network.First,the analysis and mathematical modeling on county distribution network have been processed in this paper.The theory and universal algorithm of the location and isolation of fault in county distribution network have been discussed and analyzed in detail.The unified matrix algorithm is mainly studied and an algorithm based on “over-current intensity” is proposed.This algorithm refrains from the problem that the terminal node could not be located by setting number 0 node.What's more,the problem of huge calculation and low efficiency is avoided by calculating the section of “over-current intensity”.This hierarchical algorithm leads to the gradual improvement of fault location.Through the above method,the rapid and accurate location of fault and the power supply of the non-fault areas are both achieved.Second,considering the characteristic of county distribution network with huge nodes and wide areas,the location and isolation of fault through FTU and DTU installed on the switch and circuit breaker will lead to disadvantage such as huge investment,long period and low precision.The proposed method with FTU and fault indicator is realized to locate faults by detecting short-circuiting and ground fault.Firstly,a large fault area could be located with FTU information.Secondly,a more accurate fault section could be located with fault indicator.The above method could improve the reliability of power supply and realize the rapid location and isolation of fault with available resources.Most county distribution networks are neutral ungrounded or grounded by arc-suppression coils which cause difficulties to detect single-phase grounding faults.In view of the above fact,the application of the dynamic resistive load which could produces specific fault signal and the combination with fault indicator are proposed to determine the fault area of the single phase grounding.In view of the current situation of the existing distribution network equipment in Rongcheng,the characteristics and deficiencies of the traditional fault location method are analyzed.The new requirements for the function of fault location in the next distribution automation system are presented.On the basis of theory research,the establishment of fast fault location system for county distribution network is illustrated by the distribution network of Rongcheng power supply company.It is analyzed in detail from aspects of the communication system,hardware equipment,software system and so on.Finally,the actual operation of the county distribution network of Rongcheng is studied.The practicability and economy of the fault location scheme are analyzed.What's more,the problems that need to be addressed in pilot stage are also discussed.