The Electric Reliability Council of Texas serves as an independent system operator (ISO), managing the flow of electrical power over transmission infrastructure in the state of Texas.

A combination of automated and manual controls grid operators adjust to maintain grid reliability by ensuring a balance between supply (generation) and demand (load). They generally consist of three main aspects:

• frequency response – short-term adjustments to maintain the grid’s oscillations at 60 hz), 
• balancing – related to frequency response but on longer time frames, to, for e.g., plan for energy resource outages due to maintenance, and 
• voltage control – involves magnetic waves to allow for the movement of watts of energy

Midcontinent Independent System Operator, serves northern Midwest, southeast, and parts of Canada