After the Merah DC Transmission Project in Pakistan was put into commercial operation, the first large-scale comprehensive

maintenance work was successfully completed. The maintenance was carried out in the “4+4+2″ bipolar wheel stop and bipolar

co-stop mode, which lasted 10 days. The total bipolar power outage time was 124.4 hours, saving 13.6 hours compared with the

original plan. During this period, the maintenance team performed a total of 1,719 maintenance tests on converter stations and

DC lines, and eliminated a total of 792 defects.

China Electric Power Technology and Equipment Co., Ltd. and Pakistan Merah Transmission Company jointly formulated a

maintenance plan through careful planning and collaboration. At the same time, both parties actively mobilized the maintenance

resources of State Grid Shandong Ultra High Voltage Company, Jilin Provincial Power Transmission and Transformation

Engineering Co., Ltd., and domestic equipment manufacturers, and gathered more than 500 technical elites from China and

Brazil to participate in the maintenance work. After careful arrangements, the maintenance strategies and procedures were optimized,

and detailed emergency response measures were formulated to ensure that the entire maintenance process was carried out safely,

orderly and efficiently. This successful maintenance has accumulated valuable experience for the operation and maintenance of large

overseas DC transmission projects.

Up to now, the Mera DC transmission project has been operating stably for 1,256 days, with a cumulative transmission of 36.4 billion

kilowatt-hours of electricity. Since it was put into operation, the project has maintained a high availability of more than 98.5%, becoming

a key artery in Pakistan’s “South-to-North Power Transmission” strategy, and has been highly recognized and praised by the local

government and owners.