In Low Voltage Distribution Network Is Single-phase Ground Fault Detection Technology And Equipment

Single-phase to earth fault happens the most frequently in the medium/low voltage distribution network. How to locate the fault line as soon as possible is an important task for ensuring the continuity of power supply. The enlargement of medium/low voltage distribution network makes the diagnosis and location of fault line become an important task especially. Power systems with unearthed or a compensated neutral are popular in China, which can improve the reliability of power supply. Long-time earthing operation, however, will destroy the systematic safe operation as the result of two-point, more seriously, multipoint earthing as well as the systematic over voltage caused by arc light. Thus how to detect the fault line quickly and accurately is an important subject in power system protection, which has not been solved completely.In order to deal with this problem, this thesis, at first, stable and transient features of single-phase to earth fault in power system with floating neutral, as well as traits and restrictions of various selecting criteria are analyzed in detail. The research has been carried out on the line selecting criteria based on different aspects of fault characteristics for many years. Many line selecting equipments on which based some of these criteria have been put into use. However, theoretical analysis and operating experiences indicate that each criterion has limits and shortages; no one can select the fault line correctly in all kinds of conditions.In this paper, we have analyzed and improved the synthetic criterion based on fuzzy principle. The "S" criterion is accessioned. The multi-criteria is integrated with several individual criterion; the selecting results can be evaluated with weight in real-time. The disadvantages of individual criteria can be overcome. It's an adaptive and dynamic method. It is independent withgrounding mode of neutral, operation mode of power distribution and the number of outgoing lines.On the basis of the BF-03 and BF-04 earth-fault-line selecting equipment, the earth -fault-line selecting equipment adopted DSP chip-TMS320C32 has been developed. This thesis has introduced software, hardware and main technological characteristic of the equipment in detail. Mainly, has reported the preliminary experiment and result debugged...