7. The future of high-voltage direct current transmission

It's worth remembering that the first power transmission lines were powered by high-voltage direct current. The very first experiments in transmission over tens of kilometers were carried out by Marcel Deprez between 1881 and 1883, first at the Munich International Exhibition, then at Le Bourget and later between Vizille and Grenoble. At the time, direct current was supplied by generators in which it was difficult to raise the voltage between brushes without quickly causing a flashover at the commutator.

Aware that the higher the voltage itself, the higher the efficiency of a transmission line, the pioneers of electrical engineering first tackled the problem by arranging several generators in series; at the same time, the various appliances were also connected in series in the circuit, operating at constant...