My total power generation, distribution and energy management is within my industry.
You can say it's like island mode..
What may be the cyber security measures to me to take?
Air gaped mode from a network perspective but the environment requires updates and configuration change - these must be carefully performed with robust control of temporarily connected assets for the actual configuration or transfer of configuration files or any data that must enter into your air gaped environment.
Today there is no islands from point of view of Cyber Security. There are zones and segmentation, and the power generation and distribution should be treated as a critical one area and protected like this. Independently where it is inside.