Within the massive body of the power system lies a hidden yet critical line of defense — relay protection. Serving as a round-the-clock loyal sentinel, relay protection constantly monitors power grid operational safety. In the event of sudden grid faults such as lightning strikes and short circuits, it will deliver accurate judgments and instantaneous responses within milliseconds without delay.

Nestled within the Gezhouba Hydrocomplex Project, hailed as the First Dam on the Yangtze River, Gezhouba Hydropower Station also boasts a reliable team of "safety sentinels". Performing steady, low-profile duties on a daily basis, the station has achieved an outstanding operational record. It has maintained a 100% correct operation rate of relay protection for 14 consecutive years. This achievement testifies that over more than 5,000 days and nights, amid numerous on-site operational tests, the relay protection system has always operated with precise responsiveness and zero failures.

From Zero to Perfection: Treading the Life-and-Death Line Between "Zero" and "Hundred"

What makes this 100% accuracy rate so hard-won?

An RCCB tripping in a household circuit protects a single electrical device. If such household protection is regarded as an individual defense unit, the protection system of a large-scale hydropower station is comparable to a multi-service army conducting coordinated operations. Slight electromagnetic interference, minor code vulnerabilities, or even trivial wiring deviations during calibration may render the protection system unresponsive amid actual grid faults or trigger false alarms under normal operating conditions.

 The system faces an all-or-nothing scenario: A flawless performance consolidates the grid's safety line, while inaccurate judgments will escalate operational risks. The relay protection system perpetually operates on the razor's edge of success and failure. To sustain this 14-year record of zero operational errors, Gezhouba Power Plant has enforced rigorous source control and lean operation & maintenance. The condition of wire cores and equipment temperature data are fully archived and recorded. All operational procedures and equipment O&M activities follow standardized protocols with complete traceability, ensuring full-process compliance and sound operational status of all equipment.

From Exclusive Experience to Standardized Manuals: Embedding On-site Expertise into Institutional Mechanisms

The 14-year zero-error record is attributable to abundant on-site experience. More importantly, its long-term stable and reliable operation is underpinned by systematic management.

Gezhouba Power Plant has summarized and refined years of frontline practical expertise into a complete standardized operation system. It has innovatively developed Standard Operating Procedure Cards, breaking down complex, variable protection work that once relied heavily on individual proficiency into clear, quantifiable and traceable standard procedures. In addition, supporting management systems including typical work orders, standard operation procedures and three-level acceptance cards have been fully implemented and dynamically updated in light of equipment operating conditions.

From internal resistance measurement of each wire core and dual verification of each setting value to stringent checks via the three-tier acceptance mechanism at team, department and plant levels, the plant eliminates uncertainties in manual operations through institutional certainty. This core logic addresses variable challenges such as personnel turnover and technological upgrading, and underpins the safe and stable operation of the relay protection system.

From Passive Defense to Active Prevention: Eliminating Risks at the Germinal Stage

If standardized procedures serve as the shield for passive defense, rigorous quality control at the source acts as the sharpest spear for active risk prevention.

As a veteran hydropower station in operation for more than 40 years, Gezhouba inevitably faces operational challenges arising from long-term equipment service. Instead of relying on passive emergency disposal, Gezhouba Power Plant adopts a proactive risk pre-control strategy and advances equipment upgrading. In collaboration with universities and design institutes, the plant conducts comprehensive hazard investigation and systematic assessment of the relay protection system. Multi-scheme comparison and simulation verification are used to ensure that every technical upgrading eliminates potential hazards and covers blind spots in system defense from the structural level.

Over the past 14 years, the plant has completed two full rounds of upgrading and renovation for generating unit protection devices, with the construction of a new-generation 500 kV intelligent substation well underway. Adopting a collaborative operational framework, the upgraded system features high reliability from commissioning onward. Its forward-looking planning and design have eliminated potential risks at the initial stage.

Fourteen years of zero-error safe operation marks a remarkable milestone and a new starting point for future development. In response to higher requirements for the new power system, Gezhouba Power Plant is accelerating the intelligent upgrading, integrating digital-intelligent technologies into traditional operation and maintenance systems. Empowered by such improvements, this strategic national asset, having withstood the test of time for over four decades, continues to operate with safety, reliability, and efficiency, making its due contribution to the high-quality development of the new power system.