Optimization Design and Engineering Application of Switching Modes for 10 kV Medium-voltage Sectional Busbar Backup Power Automatic Transfer

Aiming at the requirement of power supply reliability for the single-busbar sectional structure of the 10 kV medium-voltage distribution system in nuclear reactors, combined with the provisions of the "Technical Code for Relaying Protection and Security Automatic Devices" (GB/T 14285-2022), this paper carries out research on the optimization of backup power automatic transfer switching modes. A mathematical model of the power grid-motor coupled distribution network is established, and the residual voltage decay characteristics of motor loads are analyzed through field measurement and simulation, revealing the dynamic evolution law of the voltage difference between the residual voltage and the power supply voltage. Engineering application verification shows that the optimized BZT system achieves a power supply continuity of 99.98%, and the motor impact voltage is ≤1.1 times the rated voltage, which meets the requirements of equipment insulation safety. This research can provide theoretical support and engineering examples for nuclear engineering and high-reliability industrial distribution systems.