difference between high voltage ac and high voltage dc
High-voltage direct current
A high - voltage , direct current ( HVDC ) electric power transmission system ( also called a power superhighway or an electrical superhighway ) uses direct current for the bulk transmission of electrical power , in contrast with the more common alternating current ( AC ) systems . For long - distance transmission , HVDC systems may be less expensive and suffer lower electrical losses . For underwater power cables , HVDC avoids the heavy currents required to charge and discharge the cable capacitance each cycle . For shorter distances , the higher cost of DC conversion equipment compared to an AC system may still be justified , due to other benefits of direct current links . HVDC uses voltages between 100 kV and 1,500 kV . 
A high - voltage , direct current ( HVDC ) electric power transmission system ( also called a power superhighway or an electrical superhighway ) uses direct current for the bulk transmission of electrical power , in contrast with the more common alternating current ( AC ) systems . For long - distance transmission , HVDC systems may be less expensive and suffer lower electrical losses . For underwater power cables , HVDC avoids the heavy currents required to charge and discharge the cable capacitance each cycle . For shorter distances , the higher cost of DC conversion equipment compared to an AC system may still be justified , due to other benefits of direct current links . HVDC uses voltages between 100 kV and 1,500 kV .
For long distance transmission, HVDC systems may be less expensive and suffer lower electrical losses. For shorter distances, the higher cost of DC conversion equipment compared to an AC system may still be justified, due to other benefits of direct current links.
For long - distance transmission , HVDC systems may be less expensive and suffer lower electrical losses . For shorter distances , the higher cost of DC conversion equipment compared to an AC system may still be justified , due to other benefits of direct current links .