Abstract: A fault phase selection method considering the impedance characteristics of single-phase contact bamboo is proposed to solve the problem of mountain fire caused by single-phase contact bamboo fault in flexible grounding distribution network. Firstly, a 10 kV single-phase bamboo fault test platform was built, and the ignition characteristics and fault evolution rules of bamboo were systematically analyzed, as well as the correlation between ignition threshold and leakage current, transition resistance and other parameters, revealing the mechanism of mountain fire caused by dead time in the traditional phase selection process; Then, based on the constructed flexible grounding distribution network model, the active phase selection trigger mechanism is introduced to significantly improve the ability of the protection to withstand the transition resistance by continuously injecting the characteristic current and monitoring the characteristic variation; Furthermore, the phase selection process is optimized, the quick response function of trigger phase selection is realized, and the problem of dead time in the phase selection process is solved; Finally, simulation analysis and field tests show that the proposed method effectively reduces the risk of mountain fire caused by single-phase bamboo contact fault.

Key words: flexible grounding device, impedance, single phase bamboo contact, active phase selection