Research and Optimization of blocking schemes of Backup Power Switch-in equipment Using Bus-bar Differential Protection in 110kV Substations

The blocking schemes of backup power switch-in equipment using bus-bar differential protection under the enterprise standard Q/GDW10767 are likely to cause whole substation blackouts. In order to solve this problem, two configurations and setting schemes of 110kV power line protection were compared, and two blocking schemes of backup power switch-in equipment using bus-bar differential protection are analyzed in this paper, and the optimal solution is obtained by a combination of both. According to the analysis, the approach of equipping 110kV power supply lines with optical fiber current differential protection, and setting the protection range of power line protection (inter-phase distance protection I and grounding distance protection I) to cover 70%~80% of the whole power line is the most favourable solution. In addition, the method of tripping section breaker before tripping all the breakers in the faulty bus and only blocking the related breakers instead of all the 110kV breakers of backup power switch-in equipment is the most satisfying blocking scheme.