Cybersecurity has grabbed the lion’s share of grid security attention, but last year’s attack on a substation in California served as a reminder that physical attacks are still a significant threat.

Legislation to protect the nation’s power grid from a wide range of threats — from extreme weather and solar storms to a cyberattack and nuclear explosions — is gaining more traction in Congress.

Physical threats against the grid have seen a sharp uptick in recent years, according to a POLITICO analysis of DOE data. Rising incidents of domestic terrorism and a surge in state-sponsored cyber ...