High Quality Content by WIKIPEDIA articles! An HVDC converter converts electric power from high voltage alternating current (AC) to high-voltage direct current (HVDC), or vice-versa. HVDC is used as an alternative to AC for transmitting electrical energy over long distances or between AC power systems of different frequencies. HVDC converters capable of converting up to 2000 megawatts (MW) and with voltage ratings of up to 900 kilovolts (kV) have been built, and even higher ratings are technically feasible. A complete converter station may contain several such converters in series and/or parallel.