The Exploitation And Development Of The Distribution Network Single-Phase-to-Earth Fault Disagnosis System

In China, most distribution network currently used small current grounded system. Because of the complexity of the network structure, the small ground current, the weak signal, when single-phase-to-earth fault occured in distribution network, resulting the problem of fault location has not a good solution way. This paper researched the exploitation and development of the distribution network single-phase-to-earth fault diagnosis positioning system. Research the fault features of ungrounded system and arc suppressing coil grounding system. Propose the fault location principle of graph theory method based on a variety of transient features, and complete hardware design and software development for fault diagnosis system.This paper analyzes the features of single-phase-to-earth fault in ungrounded systems and arc suppression coil grounding system. Based on this determined to locate the fault using the transient fault information. Proposed using four methods include wavelet transform, Prony algorithm, transient energy method and the first half-wave method to extract the transient features. And research the two search methods in graph theory tree, breadth-first traversal search and deep-first traversal search; choose the breadth-first search traversal as the search method to fault location.This paper determines to use the fault location principle of graph theory method based on a variety of transient features. That based on the transient features criterion of the four algorithms to breadth-first traversal search the fault line, then locate the fault section of each algorithm, and determine the final fault section by way of poll. And the fault location principle of graph theory method based on a variety of transient features is verified by simulation to suite to both the grounding system and high positioning accuracy.In this paper, complete hardware design of feeder terminal unit. Feeder terminal unit have a practical functional improvements base on the CSC271e feeder terminal unit of Beijing SIFANG Automation. And describe the overall design of the feeder terminal unit, narrowing the chassis; increasing the transient characteristics of the telemetry information upload; modify the zero-sequence voltage and current collection function; increasing the zero-sequence voltage detection function. And the terminals block definition.In this paper, the fault feature extraction algorithm implementation process for feeder terminal unit has been designed in detail. And for hardware situations of feeder terminal unit, choose the VxWorks embedded operating system and describe the development environment Tornado in detail. Completion of feeder terminal unit algorithm program, and introduce variable definitions, main functions and algorithms calculation functions.In addition, the paper design of distribution network fault diagnosis system, run before the actual hanging, on RTDS real-time digital simulation platform experiments were conducted. Experimental results show that the fault positioning principle proposed is effective, design of fault diagnosis system can accurately and quickly locate the fault.