Faulty Line Detection Method Based on Optimized Bistable System for Distribution Network

The noneffectively neutral grounded distribution network is called small current to ground system (SCGS) in China. When single-phase to ground fault occurs in SCGS, the fault current is weak, and the noise impairs the feature of fault current, both of which make faulty line detection difficult. This paper presents a faulty line detection method for SCGS, based on optimized bistable system. The proposed method consists of two steps: 1) The optimized bistable system, whose potential function parameters are optimized by particle swarm optimization algorithm, is used to extract transient zero-sequence current (TZSC) in strong noise background; 2) the optimized bistable system and cross correlation coefficient are used to propose a faulty line detection criterion, it based on squared distance, which contains the waveform difference and energy of TZSC. Simulation and field experiments prove that the method can detect faulty line exactly with various fault situations, such as different signal-noise ratios, grounding resistances, initial angles, faulty lines and unbalanced load.