High Voltage Direct Current (HVDC)

For bulk transmission of electrical power between two station a high voltage direct current is used refer as high - voltage , direct current (HVDC). This type of power transmission system is more efficient and cost effective as compare to AC transmission systems for long distance transmissions.

For underwater cables or also called submarine cable this type of transmission system is very much helpfull to reduce the overall cost and power loss between transmission. As wire under water consume too much power while charging and recharging its capicitance per cycle.

For long distance current transmission HVDC is always cost effective and benificial than AC current system. However for short distances again HVDC is more usefull over AC by various other advantage factors of direct current (DC).


For AC unsynchronised systems HVDC allowed very efficient power transmission when power flow can be controlled without affecting the phase angle between source and destinace load. Even in case of rapid change HVDC can stablized immidiatly. HVDC can also transfer power between two power grids where there is diffrenct in power frequncies.

Examples of HVDC

In 1930s between sweden and Germany
in 1951 between Moscow and Kashira
During 1954 a 20 MW system between Gotland and Sweden
Between Xiangjiaba and shanghao ( 2nd largest largest 2071 Km)

Rio Madeira in brazil (largest 2,375 KM)