Fuzzy Comprehensive Evaluation for Electromagnetic Loop in China Ultra-high Voltage Grid

In initial period of ultra-high voltage grid, 1000 kV/500 kV loops, perhaps even 1000 kV/500 kV/ 220 kV loops, will turn up. The hazards caused by electromagnetic loop are discussed from two sides involving power transfer and short-circuit current level. Multi-level electromagnetic loop of North and Central China power grid in the planning year 2010 are analyzed. A method combining analytic hierarchy process with fuzzy logic theory is employed to comprehensively evaluate opening schemes for electromagnetic loop. Evaluation results indicate that multi-level electromagnetic loops should be avoided by opening extra-high/high voltage loops promptly. Furthermore, it´s also necessary to open ultra-high/extra-high voltage loops reasonably.