Design And Implementation Of Single-phase Faulty Line Detection Device In Small Current Grounding System Based On Multiple Criteria Fusion

Small current grounding system single-phase ground fault occurs in the highest probability, can be accounted for80%total failure. When single-phase ground fault occurs, relay protection can selectively send a signal and do not have to trip immediate, power system continues to run the1-2h according to safety rules. However, with the large-scale use of the cable line, the system capacitor current increases, long ground run may develop into a two-phase short circuit, affecting a wide range of intermittent arc easy to induce overvoltage, damaging the safe operation of the equipment, destructing system. Therefore, the research on the small current grounding fault line selection device helps to find the faulty line in time and to be removed to reduce the impact of the failure of the powered.Active power is the only current line selection method for original grounding fault line selection device in Qian Steel. The faults of incomplete fault information in this method make missing and error often occur when applied. Therefore, the improvement is necessary for the small current grounding fault line selection device in Qian Steel.The main works of this dissertation are as follows:(1) Small current grounding fault line selection device in Qian Steel was introduced, and the defect of the principle of the original line selection device line selection was analyzed;(2) On the basis of the research on the principle of the line selection method of five harmonic, active power and energy, the small current grounding fault detection method based on multi-criteria fuzzy control decision-making fusion is proposed, which makes the fault information more comprehensive; (3) In order to achieve the small current grounding fault line selection device based on the proposed method, based on the80C198microcontroller to design the hardware and the software of the system, which including the central unit, data acquisition module, power module, the man-machine interface module, and communication module;(4) Run the improved small current grounding fault line selection device in the industrial field, the accuracy rate of the designed small current grounding fault line selection device reached95%.The results of industry application showed that the improved single-phase faulty line detection device in small current grounding system based on multiple criteria fusion was suitable for the power supply system in Qian Steel.