Introduction  In order to connect isolated data between various stages of the entire life cycle of substation projects and achieve the flow of geometric model and engineering information, a graph-based data model for substation projects is proposed in this paper.

  Method  Firstly, the flow of geometric and engineering information of the model in each stage of the substation project was analyzed, and the data model was divided into core model and scene model. Secondly, the topological structure of graphs was organized according to the civil part and electrical equipment of the substation project. Then, the relationship between the components of IFC model with a tree structure was converted into the form of "edge", the model components were converted into the form of "node", and the graph structure was then constructed and imported into the graph database. Finally, a data model structure for substation projects at the component level of electrical equipment was designed, and the model was associated with the components of the core model to form a graph-based data model for substation projects.

  Result  The test results show that the graph-based data model for substation projects can achieve flexible combination and decomposition of geometric model and engineering information model after being imported into the graph database. It can realize efficient modification and query of model component information in the face of complex relationships between a large number of geometric structures and attribute information.

  Conclusion  The graph-based data model can simultaneously carry geometric information and engineering information scene models. It meets the requirements for adjusting the granularity of models and supplementing and removing engineering information at various stages and can provide users with an intelligible data flow process comparing with the COBie (Construction Operations Building information exchange) standard based on form management.