while learning about hvdc, I read that high voltage dc cannot be generated due to commutation problems. can anyone please explain me, what does that commutation problem refer to?
Switching off a DC current powered by a high voltage source produces an electric arc much stronger than in case of AC.
In case of AC, the strength of this high electric field that is built between the switch contacts (to cut off the current) is reduced automatically when the AC voltage (its absolute value) decreases and crosses zero volt.