Poseidon power substation PX-01 is a location in the Forest region of Appalachia in 2102.
This fenced off power station has one shack containing some junk items. It is populated with several Scorched. Two copper veins can be found next to the station.
There is also a power box which requires activating the Poseidon Energy Plant WV-06 here, but otherwise there's very little loot.
The Poseidon power substation PX-01 appears only in Fallout 76.