the main limiting factor for long AC cables is the capasitive current tha depends on the voltage and capacitanse of your cable.
The worlds longest AC cable (as of today) is the 162 km 3~ subsea cable connecting the Martin Linge oil platform to the Norwegian main grid.
Shunt compensation will increase the maximum length, but by how much depends on the cable system and layout, thus a general answer to that is not possible to give.