Abstract: Large capacity hydroelectric generating units face dual technical bottlenecks of short-circuit current exceeding limits and transient recovery voltage distortion during grid connected operation. The rational configuration of generator outlet circuit breakers (GCB) and deep optimization of electrical main wiring topology have become the core paths to improve the operational reliability of hub power stations. The article analyzes the technical and economic feasibility of GCB configuration schemes for large and medium-sized hydropower station units, and proposes a topology optimization strategy for the main connection considering the dynamic characteristics of GCB, aiming to improve the thermal stability margin and power supply continuity of the main connection system.