Research On Key Technologies Of Single Phase To Ground Fault Indicator Based On Wireless Communication

Power grid is an important part of the power system.It has been extended from the substation to the end user,bearing the power transmission and distribution of the important tasks.The distribution network has long line and a large number of branch.The number of installed insulators and the number of arrester is large.The number of connected devices is large and the load is varied,and the geographical environment of the line is complicated.These cause the frequent occurrence of distribution network failure,and the user’s power failure is mostly caused by the distribution network fault.As an important part of the construction of smart grid,the intelligent distribution network faced with the occurrence of small current single-phase grounding fault,and how to locate the fault section of line quickly and accurately can be a huge problems to us.At present,there is a series of difficult problems such as refusal and malfunction of single-phase short-circuit fault by the traditional fault indicator.This thesis studied the single-phase-to-ground fault detection technology of distribution lines,and the validity of transient method is verified by MATLAB Simulink modeling and simulation;Fault indicator,using GPRS and ZigBee wireless networking solutions,can greatly improve the communication efficiency;The thesis puts forward the working example to verify the practicability of the technology;And the measurement error of current transformer based on Rogowski coil is studied.The advantages of the measurement accuracy of the Rogowski coil are verified by modeling and simulating the linear saturable current transformer;A shielding scheme of current transformer based on winding shielding principle is proposed to reduce the influence of stray flux on the measurement accuracy of current transformer;This thesis made a mathematical derivation for the contrast difference and angle difference and designed a compensation scheme achieved by the Labview 2016 programming software;The digital integrator of the current transformer is obviously designed,and then a digital integrator algorithm is proposed and the validity of the algorithm is verified by Simulink module simulation of MATLAB;In the fault indicator self-power program selection,the thesis used current transformer based on the self-power technology and super capacitor together to ensure that the fault indicator can have a normal operation,and then the mode of current transformer is analyzed.In this thesis,according to the problems of traditional grounding fault indicator,the fault indicator is designed to improve the programming.And the indicator using transient method to detect small current single-phase ground fault can make a small current single-phase ground fault judgement more accurate.The online monitoring terminal made of fault indicator and communication terminal can accurately measure the line current and carry on a high-speed recording.And through the help of the Rogowski coil,the monitoring terminal can further achieve the purpose of accurate detection of line failure.Through the above improvement measures,the operation and maintenance personnel of the distribution network can locate the fault section more quickly,thus shorten the query time of the line fault and further shorten the response and processing time of the line fault.Finally,the above measures can reduce the power failure time and improve the power supply reliability.