Technology for Improving Backup Protection of Extreme Working Conditions Based on Station Information

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In substations, there is an extreme working condition in which the line interval loses the double main protection and a short-circuit fault occurs again. In this extreme working condition, the backup protection may have problems of slow fault removal or misstepping or refusal of overstepping. This paper analyzes the limitations of the configuration settings of the existing backup distance protection and zero-sequence protection for the above extreme conditions caused by the blocking of protection equipment, communication equipment failure and channel damage. According to the characteristics of different extreme working conditions, an extreme working condition recognition logic based on the shared information of the station domain is proposed. Combining the identification results of the station domain, the backup protection acceleration trigger mechanism of the substation under extreme operating conditions and the passive protection trigger acceleration mechanism of the corresponding interval of the neighboring substation are proposed. After the acceleration is triggered, the operation time of the backup protection is shortened, and the range of the backup protection corresponding to the interval between the neighboring substations is adjusted to realize the remote backup. A simulation platform was built on the RTDS platform in combination with the switching device of the station domain and the optimized line protection. The simulation results verified that the optimized backup protection can quickly and orderly remove the fault when the short circuit fault occurs after the main protection is lost due to different extreme conditions. The level of safety and stability of the UHV transmission system has been improved.