In order to solve the problems of long development time

poor expansibility and small application scope in the digital design of secondary system of intelligent substation at present

this paper puts forward the 3D assembly techniques based on the expanded model by analyzing the integration of secondary model files of intelligent substation.In the design process of this method

the relationship between primary equipment and secondary equipment

the mapping between logical circuit and real circuit are fully considered.By using standard family library techniques

file analysis techniques and automatic mapping techniques

the coupling between physical model and logical relationship is realized.Taking the actual 220 kV intelligent substation as the pilot

the three-dimensional model in secondary system simulation analysis

online monitoring and The application of fault diagnosis shows that the techniques can effectively improve the efficiency of three-dimensional design and maintenance of secondary system.