A high-voltage, direct current (HVDC) electric power transmission system uses direct current for the bulk transmission of electrical power. A long distance point to point HVDC transmission scheme generally has lower overall investment cost and lower losses than an equivalent AC transmission scheme. HVDC conversion equipment at the terminal stations is costly, but the total DC transmission line costs over long distances are lower than AC lines of the same distance. HVDC requires fewer conductors per unit distance than an AC line, as there is no need to support three phases and there is no skin effect.
- Voltage source converters (VSC)