The power system is a key infrastructure that can be targeted by cyber attacks. Many modern armies have cyber warfare divisions that prepare for attacking the key IT infrastructures. Presumably, power systems could be among the targets. For example, cyber attack against the power system was used in the Ukrainian conflict. Smart Grid is in many aspects reliant on communication between the devices and thus could be more vulnerable to various attacks.
The attached (relatively old) video displays how white hackers (hired by the power company) from Red Team Security penetrated different substations and gained access to the system.
Have you noticed some other hacking cases besides Ukrane? Some other nice video on the topic? Someone among us working on the field?