Unfortunately, as of today I don't think you can easily model substation equipment in Revit. I think you can certainly export models from something like Inventor into models/families that will work with Revit, but I'm afraid that there are no IFC or BIM data structures for high voltage equipment today. We are looking at this ourselves at my company, and although I think the possibilities are there, I don't think that Revit can do Substations very well today. Visually, sure, I think you can get there, but I don't think that the data is there, nor the connectivity.
I'd be very happy to be wrong here, so don't worry about calling me out and telling me that I'm wrong.