Override trip-prevention protection method and system

The invention relates to an override trip-prevention protection method and system and belongs to the field of relay protection. According to the override trip-prevention protection method and system of the invention, all the protection devices of substations at all levels of an underground power supply system are divided into a plurality of blocks with bus-bars adopted as basic units; a pluralityof intervals are determined according to the blocks of adjacent levels; the intervals judge whether faults exist in the intervals or not; if faults exist in the intervals, upper-level side protectiondevices in the intervals trip, locking information is sent to the upper-level side protection devices; and if faults do not exist in the intervals, the upper-level side protection devices in the intervals are locked, locking information is sent to the upper-level side protection devices, meanwhile, lower-level side protection devices in the intervals carry out fault detection, and the lower-levelside protection devices sen