Abstract: In the light of the problem that the prefabricated substation can not extend the secondary system function with effective information,a prefabricated cabin comprehensive protection system for secondary function expansion and centralized protection is proposed based on the advantage of information centralization of prefabricated cabin substation. A new strategy of transformer overload protection is proposed based on low importance lines and low-frequency load shedding strategy considering the importance of load and frequency regulation characteristics. The proposed system can optimize the protection configuration of prefabricated substation,and improve the implementation and performance of conventional protection. Based on PSCAD/EMTDC simulation software,a 110 k V prefabricated substation simulation platform is built. The simulation results verify the effectiveness and feasibility of the prefabricated substation integrated protection system.