Fast Fault Section Locating Method Of Small Current Grounding System

The distribution network in China mainly uses the small current neutral grounding system. A good solution for location of single-phase-to-earth faultin distribution network has not been proposeddue to the small grounding current and complex networkstructure. This paper researchesmainlyon both application of the key technologies of automation system in Shenyang distribution network and fault features of non-grounded system as well as arc suppression coil grounding system,putting forward the steady state characteristics as the positioning principle of fault location, and hardware design and software development ofthe fault diagnosis systemhas been accomplished.This paper analyzes distribution automation of Shenyang power grid, and also the fault feature of non-grounded system and arc suppression coil grounding system. On this basis, method for fault location by the steady state fault information is determined.This paper presents a fault location principlebased on variety ofsteady state characteristics,obtainsthepositioning section from each algorithm,andthese results can accurately determine the fault section. Through the simulation experiment, it’s verified to suit both the two types of system and high positioning accuracy.Then,in this paper,thehardware design of two remote-type feeder terminal unit iscompleted. "Two remote" type terminal mainly design four important parts including the CPU chip, A/D signal acquisition system, RF module and GPRS communication module. For chip selection and hardware design,this paper does in-depth analysis and research.In this paper, the fault feature extraction algorithm’ programming realization of terminal has been designed indepth.Based on hardware’s characteristics of "two remote" type terminal, theembedded operating system has been chosen, and development environment is introduced in detail. Program structure of "two remote" type terminal is accomplished with multithreading modulardesign.In addition,before being put in the actual operation ofdistribution network,the fault diagnosis system has been demonstrated effective and accurate by theall sections of different types of faultssimulation test on the RTDS platform.