The future belongs to dc: Edison will beat Tesla after all

For about a hundred years following the war of the currents (between Edison and Tesla), settled at the end of the 19th century in favor of ac, transmission and distribution (T&D) systems have followed the well-established architecture still in use today. The bulk of the power is generated using large synchronous machines (driven by steam and water turbines) that are connected to step-up transformers operating at 50 or 60 Hz. Then, extra high-voltage and ultrahigh-voltage ac transmission lines carry electric power over long distances to the consumption centers. Next, a series of cascaded step-down transformers reduce the voltage for the different functions (such as subtransmission and distribution) and applications (such as industrial, commercial, and residential). Since the 1950s, various high-voltage dc (HVdc) projects around the world have demonstrated that dc transmission is economically viable for high-power long-distance transmission.