The secondary circuit of the intelligent substation adopts fiber optic digital transmission

and its "virtual circuit" characteristics result in opaque physical connections

making fault diagnosis difficult. Therefore

this article proposes an intelligent warning and fault diagnosis method. This method first models physical entities such as process layer switches

IEDs

and optical cables to construct a complete physical link topology; Secondly

by parsing the SCD file

the logical virtual circuit is accurately mapped to the physical topology

forming a panoramic view of virtual real fusion; Furthermore

a diagnostic model based on multi-source information correlation analysis is established

which utilizes the link alarms and real-time communication status sent by the device

combined with the coupling relationship between virtual and real topology

to achieve probabilistic sorting and accurate positioning of faulty physical nodes. Engineering applications have shown that this method does not require additional hardware and can significantly improve operational efficiency.