The refrigerated container ship with AC440 V main distribution network cannot achieve the maximum loading capacity of the reefer container during the handling of the reefer containers at port or must turn on the main generator for power supply, due to the maximum capacity limitation of 6 300 A for the AC440 V air circuit breaker (ACB) and the limited capacity for the 4 800 kVA single step-down transformer. In the current study, the power can be supplied independently on both sides of the low-voltage main distribution board by adding one output panel on the traditional high-voltage shore power change-over panel and a step-down transformer to the main circuit. The capacity limitations of the ACB and the step-down transformer can then be solved to maximize the total capacity of the shore power system and achieve automatic safety interlocking protection and operation process guidance. It can effectively improve the safety of ship operation and economic benefits.