Research on hidden problems of old protection based on bus protection remote trip and failure start-up loop

Abstract

Combined with the hidden failure of misfiring remote trip when the double buses junction bypass pending, it was analyzed of bus protection operation without line protection function platen and remote trip on the opposite side without cause. Meanwhile processing strategies of bus protection about disconnect switch position, secondary circuits of optical-fiber longitudinal difference protection and the opposite side to receive remote trip were studied, and rectification measures such as withdrawal platen of bus protection for tripping circuit breaker when the circuit breaker was overhauled and the renovations for old protection were proposed;in the verification of the failure start circuit of power plants, it was found that standby transformers were not designed to start the failure and release the voltage blocking circuit, and the current settings for double sets of bus protection were inconsistent. And then different functional modes and the considerations for the rectification of the settings were introduced to avoid the special points of the protection in terms of devices, circuits and functions in different periods and to provide an reference for the operation and maintenance of many similar substations and power plants with old protection.