China’s Gezhouba Hydropower Station has recorded a 100% correct operation rate for its relay protection systems for 14 consecutive years, according to operator Gezhouba Power Plant.
The record covers more than 5,000 days of operation without an incorrect relay protection response. The systems monitor the power station and grid for faults such as short circuits and are designed to initiate protective action within milliseconds when abnormal conditions are detected.
Located at the Gezhouba complex on the Yangtze River, the hydropower station has been operating for more than 40 years. The operator said maintaining the protection record has required a combination of equipment monitoring, standardised operating procedures and upgrades to ageing systems.
Gezhouba Power Plant archives information including the condition of wire cores and equipment temperature data, while operation and maintenance activities are recorded to provide traceability.
The plant has also developed Standard Operating Procedure Cards for relay protection work, replacing processes that previously relied heavily on the experience of individual personnel with defined and traceable procedures. These are supported by typical work orders, standard operating procedures and three-level acceptance cards, which are updated according to equipment operating conditions.
Technical measures include internal resistance measurements of wire cores and dual verification of protection setting values. Work is also subject to a three-tier acceptance process at team, department and plant level.
The operator said the standardisation programme is intended to reduce the potential for human error while maintaining consistent procedures as personnel and technologies change.
Equipment modernisation has also formed part of the strategy. Working with universities and design institutes, Gezhouba Power Plant has carried out assessments of the relay protection system and used alternative scheme comparisons and simulation verification when developing upgrades.
During the 14-year period, the plant has completed two rounds of upgrades and renovation work on generating unit protection devices.
Construction of a new-generation 500kV intelligent substation is also underway as part of the wider modernisation programme.
Gezhouba Power Plant said it is now accelerating further intelligent upgrades, including the integration of digital technologies into its existing operation and maintenance systems, as it seeks to maintain the reliability of protection equipment at the long-serving hydropower facility.
