Research Of Detection Method On Small Current Fault Location Based On Technology Of Internet Of Things

Most of distribution networks in China are resonance grounding system. In various types of overhead line failures, single-phase ground fault takes the largest proportion. Online fault detection and location are the basis of self-healing function of smart grid, the application of fault-line-selection is relatively mature. Based on fault-line-selection, online fault location was proposed. It aimed at quickly identifying, eliminating single-phase groundfaults while ensuring the electricity supply. The ultimate goal is to improve power supplyreliability.Sampling accurate run-time information is the most important step of fault location.Distribution networks run within large area and have a lot of branches, many methods andtechniques of internet of things could help to accurately, efficiently capture the runtime state of power grid. Studied the DMTS algorithm which is a time synchronization method in wireless network. Analyzed the delay of wireless data transmission, modeled the delayby introducing Gaussian distribution. Using the maximum likelihood estimation method to get an unbiased estimation of the time offset, finally proposed a time correction algorithm.This article mainly focus on resonant neutral grounding system. Analyzed the characteristic of zero-sequence voltage/current when single phase ground fault occurs. Use wide-area amplitude comparison method as the basic theory to achieve online fault location. Then developed the online fault location system. This system is constituted by wide-area synchronized phase measurement, remote bilateral communication, automatically buildingand maintaining data communication network, using DMA to parallel computing and datatransmission. Used stm32f103re as the main micro control unit, which is based on ARMcortex-m3series cores. Signal sampling was triggered by GPS signals. Computed voltage/current information by using Fast Fourier Transform. By analyzing internal and externalinterrupt events, determined the interrupt priority and programmed the interrupt routines.Designed the hardware/software unit of the system. Tested the whole system in both laboratory and real distribution lines.