Faced with multiple large-scale development demands in Yiwu, several 110 kV dedicated substations were required. The nearby 220 kV Southwest Substation was operating at a load rate of 68%, with insufficient spacing for 110 kV outgoing lines. Meanwhile, construction had to proceed without interrupting busbar operation, under strict space and scheduling constraints.

With government funding support, State Grid Corporation of China required the completion of the No. 4 main transformer and bay expansion within six months. By adopting a prefabricated cabin-based modular solution, the project enabled rapid deployment, minimized on-site construction, and ensured safe and efficient expansion under live conditions.