While not directly related to hacking, this was partly addressed in Executive Order 13920 [federalregister.gov] which banned equipment and investment in the bulk-power system from foreign adversaries. Enforcement of this was suspended in section 7 (c) buried in Executive Order 13990 [federalregister.gov] that was the high profile EO that stopped the KeystoneXL pipeline project.

For those not interested in reading the full EOs, there is a FAQ [energy.gov] on the DOE website.