How to distinguish and regulate the voltage level of transmission power?

How to distinguish and regulate the voltage level of transmission power?
There is no particularly strict standard, and as the line voltage level becomes higher and higher, the distinction between voltage levels also changes somewhat. At present, generally speaking: 35kV, 110kV, 220kV, and 330kV are high voltages; 500kV, 660kV, and 750kV are ultra-high voltages. High voltage; 800kV and 1000kV are UHV.