Abstract: The real-time and reliable transmission of substation protection trip information is critical for power grid dispatch centers to respond swiftly to faults and ensure the stable operation of the power grid. By analyzing case studies of transmission interruptions in substation protection trip information, this study identifies the power supply chain and the information transmission chain. By analyzing the operating principles of UPS systems and mathematically modeling reliability block diagrams, we quantitatively analyze the mechanisms of redundancy failure in secondary power supply circuits and propose solutions such as phase-separated power supply retrofits, UPS equipment upgrades, and optimization of the operation and maintenance system. The research findings indicate that enhancing the power source independence of the secondary power supply system, as well as the availability and monitorability of backup power equipment, is central to improving the reliability of telecontrol communications.