The Research on Multi criteria Locating Strategy for Single phase to ground Fault of Non utility Grounded System Based on the Fuzzy Theory

The current caused by single phase to ground fault in NUGS is very small, and to select line correctly is a hard issue. Some proposed methods that are used to select line have their limitations and shortcomings, such as low reliability. In order to solve this problem, the fuzzy fusion decision making based on fuzzy theory is used to deal with multiple kinds of line selecting intelligently. By multi line selecting for branch line from substation to load, the single phase to ground fault in NUGS can be located. In addition, taking three kinds of line selecting modes that include amplitude comparison method for zero sequence current, wavelet analysis method and 5th harmonic component method as example, the simulation is carried out by fusion decision making. Results show that the proposed method of fuzzy data fusion from multiple line selecting has higher credibility. .