The Design Of Power Cable Fault Detection And Positioning System

The fault of power cable can exert tremendous influence on the urban electricity supply. The power cable fault detection and positioning system is dedicated to providing accurate information of fault location in a short time. In this thesis, a new detection and positioning system with accuracy, intelligence and portability was presented. The overall design of the system and the prototype design of the core equipment positioning device were also introduced.The system consists of three functional parts:Devices, Network and Service. Devices include locator, cable path detector, and high voltage generator. The locator processed detection of open-circus fault and low resistance short-circus fault by Low Voltage Pulse method based on the Traveling Wave Principle and achieved positioning by Wavelet Singularity Detection method. The cable path detector was used to fulfill diagnose of the on-the-spot faults under method of the Signal Injection. In conjunction with locator, the high voltage generator accomplished detection and positioning of high resistance short-circus fault by Twice Impulse Process. Network contained a server and a terminal module, functionally supporting Devices and Service part. Service provided remote service, historical data management, system update, system expansion and etc.The locator was equipped with Xilinx Zynq-7000 processing platform, which integrates an ARM-based processor into a FPGA instead of traditional dual core architecture (FPGA +ARM), in order to realize high speed acquisition and obtain better expansibility. The locator software was developed by Xinlinx Vivado Design Suite. The Verilog language was utilized for the block design at the FPGA level while the C language was used to develop the embedded software at the ARM level. In addition, the design of simulation server program and simplified human-computer interaction program were completed as well.For data analysis, the application of the Wavelet Singularity Detection Algorithm on the locator was fully discussed. Meanwhile, the quadric B-spline wavelet was applied to decompose the signal. Through searching the modulus maxima of the wavelet detail coefficient, the fault positioning and distance calculation were automatically implemented. For the purpose of excluding some judgment errors, the signal polo power was defined to pre-process the signal, finally leading to precise positioning.