Recently, the four-year retrofitting of unit protection devices for all 22 hydro-generators at Gezhouba Hydropower Plant was successfully completed. This milestone marks a comprehensive plant-wide upgrade of the plant's relay protection system, significantly boosting both operational safety and regional power supply reliability. This also lays a solid foundation for a successful start and solid progress to the 15th Five-Year Plan.

As the first dam on the Yangtze River, Gezhouba HPP shoulders the critical missions of flood control, power generation, and navigation. As the core "guardian of safety" for the power plant, the unit protection devices perform critical functions: real-time monitoring of operating parameters, alerting to abnormal unit conditions, and rapidly isolating equipment faults. Its response speed and precision directly determine the safe and stable operation of the entire facility. To further enhance the performance of unit protection devices and better meet the demands of the new power system, Gezhouba HPP, owned and operated by CYPC, launched a comprehensive retrofitting project in December 2021 to upgrade the protection devices for all 22 generating units and their auxiliary equipment.

“In relay protection, it's a binary outcome, either 0 or 100—there's no middle ground between success and failure. Every connection and every calibration leaves zero margin for error," said SHI Benteng, Director of the Protection Division of Electrical Maintenance Department at Gezhouba HPP. "This retrofit was a tough battle. We faced technical hurdles like a vast range of equipment vintages, diverse models, and the complex integration of new and old systems. On top of that, we had to work around strict water flow and power generation schedules. But we had to rise to the challenge.

The project team adopted a precise, step-by-step approach to tackle each challenge head-on. To overcome the challenges of integrating new and old systems, the team optimized the legacy system configurations and built an interoperability "bridge", ensuring a seamless transition and smooth compatibility between the old and new equipment. For the different unit types, the team developed tailor-made "one unit, one plan" commissioning strategies. By scientifically selecting new protection devices and meticulously calculating setting parameters for each unit, they effectively "custom-fit" the upgrades. This ensured consistent protection standards and perfectly matched operating logic before and after the retrofitting. Meanwhile, leveraging their independently developed system for dynamic setting value calculation and documentation integration, the team achieved fully automated verification of protection setting values. This technical innovation significantly boosted the efficiency of the retrofit, ultimately cutting the commissioning cycle for a single unit by nearly 30% and ensuring the project was completed with both high quality and exceptional efficiency.

This retrofitting is not only the upgrading of protection equipment, but also an intelligent leap of the traditional operation and maintenance mode. In the past, operation personnel relied solely on the central signal panel in the central control room for limited information. Today, thanks to the deep integration of the Protection Fault Information System with the holographic monitoring platform—and the comprehensive data access of non-grid-connected units—staff can now achieve panoramic, remote oversight of the protection status of all units right from their offices. They can retrieve fault reports and operating waveforms in real time, marking a true shift in monitoring from "local" to "plant-wide". This establishes a dual barrier of "intelligent monitoring + active defense" for unit safety, while also providing replicable and scalable practical experience for similar large-scale protection retrofits.

As the 15th Five-Year Plan is fully underway, strengthening energy infrastructure and enhancing the resilience of the power system have become key initiatives for safeguarding national energy security. The successful retrofit of the unit protection devices at Gezhouba HPP stands as a concrete and robust implementation of these strategic requirements. This time-honored major national infrastructure is injecting surging momentum into serving the national energy security strategy and promoting high-quality development with enhanced reliability.