On May 27, with the successful commissioning of the No. 1 main transformer at the 220kV Wenfeng Substation, State Grid Anyang Power Supply Company concluded its largest spring inspection project of the 2025 main grid after 15 days of comprehensive maintenance. The project provides a strong guarantee for the stable operation of the western Anyang power grid during the upcoming summer peak.

Comprehensive Preparation to Lay a Solid Foundation

According to the overall plan, the company carried out oil replacement and routine maintenance on the No. 1 main transformer at Wenfeng Substation. To ensure the success of the project, a dedicated task force was established and preparations began 40 days in advance. Maintenance personnel conducted five on-site surveys, analyzing historical defects, operational conditions, and grid load characteristics. Each maintenance task was broken down into detailed steps with clearly defined technical standards, safety protocols, and responsibilities. A tailored maintenance plan and contingency measures were also formulated.

Key components such as insulating oil and on-load tap changer parts underwent three rounds of quality checks, and tools and equipment were strictly managed to ensure all parameters met safety and performance standards—fortifying the first line of defense before operations began.

Multidimensional Efforts to Overcome Challenges

Faced with a tight schedule, numerous complex tasks, high risks, and the need for cross-disciplinary coordination, the company implemented scientific and precise strategies. Dedicated supervisors were appointed at each work site to build a comprehensive safety management system, ensuring the project progressed safely and efficiently.

During the oil replacement process, the team worked around the clock, performing vacuum extraction and hot oil circulation, operating in 24-hour rotating shifts while continuously monitoring key data to ensure smooth oil replacement. For internal transformer maintenance, workers overcame heat and confined conditions to meticulously inspect every contact and winding. New insulating oil underwent chromatographic analysis to ensure quality, safeguarding the maintenance outcome from all angles.

During inspection, technicians detected erosion on the grounding switch contacts of Wen 221 and Wen 111, which seriously affected conductivity. The team swiftly allocated spare parts and eliminated the defects on-site. Additionally, a crack in the A-phase bushing on the low-voltage side posed a potential oil leakage risk. It was promptly identified and resolved with a replacement, followed by monitoring to confirm the issue was fully addressed—securing the transformer’s safe and stable operation.

End-to-End Quality Control

The company implemented a full-cycle “planning-execution-acceptance” quality control system with a three-tier quality inspection framework. Each stage of the process was strictly monitored, including transformer withstand voltage and partial discharge tests to ensure optimal equipment condition before being put back into service.

This maintenance project demonstrated State Grid Anyang Power Supply Company’s dedication to work ethic and risk management. Moving forward, the company will continue enhancing equipment reliability, injecting new momentum into the power grid's safe and stable performance during the peak summer season and laying a solid foundation for its high-quality development. (By Yang Xinkang)