Design Of A Fault Indicator In Distribution Network Based On LoRa Wireless Technology And Optimal Configuration

At present,the intelligent degree of 10kV distribution network in our country is low,and the grid structure is poor.Distribution network can distribute electric energy,So it directly has impact of the reliability of the power supply system.Distribution network covers a wide range and have a lot of branches.When the fault occurs,especially the single-phase ground fault,it is difficult to find the fault location.In order to help crews locate the fault section and short fault time,the fault indication device has been widely used in distribution network.However,most of the fault indicators on the market have the following problems:First of all,some fault indicators need to work with FTU,with the help of FTU high precision voltage transformer measurement voltage to achieve fault judgment,but all installed fault indicator location are additional FTU will undoubtedly increase the cost,it is also unrealistic to add FTU for overhead line;Second,most of the fault indicator are use GPRS realize communication with monitoring station,but the distribution network is spread all over the city and countryside,the GPRS signal is not stable and reliable in some places.In addition,for the long line overhead line,the method of configuring the fault indicator is also rarely studied,the way to install fault indicators in our country is to install them superfluously.This approach is not only costly,the effect may not be obvious.A fault indicator based on LoRa wireless communication is designed in this paper.Firstly,The characteristics of fault current of distribution network short circuit and single-phase-to-ground fault are analyzed,and the fault judgment and fault line selection principle are introduced.Secondly,this paper detailed the design of its hardware and software,including Single-chip control module,power supply module,current signal acquisition module,alarm output module,LoRa wireless communication module etc.On the basis of the application of the fault indicator,the adaptive principle is used to identify the fault,And set up the short circuit experiment platform to verify the design of the fault indicator can identify the short-circuit fault and anti false alarm waveform.Single phase to ground fault is used the "S" method to determine the fault point,and the effective value of the injection signal is calculated by the differential filter and Fourier series algorithm.Communication on the use of LoRa communication and GPRS communication method,to achieve the 1 data collector management of 30 set of fault indicator.the disadvantages of GPRS communication are avoided.Using VC + + design PC interface,to achieve the fault indicator information collection and command control.In addition,this paper also studies indicator installation configuration problem in the long line overhead line.Based on the principle of economy,considering the cost of fault indicator's installation and the efficiency of the outage time,the objective function is presented.The objective function is solved by genetic algorithm based on the example,the feasibility and significance of the optimal configuration are proved,and the advantages of the fault indicator based on LoRa communication are analyzed.