Description: In early invention of electric energy, dc power was used but due to limitations of low voltage dc systems, ac systems become popular. With increase interconnection and loading of power system, the factors such as are reactive power, stability, power control, etc, impose limitations on the amount of power to be transmitted over ac lines. With advent of high voltage semiconductor devices, it has been possible to go for high voltage dc (HVDC) transmission for long distance power transfer. Semiconductor technology enabled the manufacture of powerful thyristors and later of new elements such as the gate turn-off thyristors (GTO) and gate bipolar transistors (IGBT). Development based on the semiconductor devices first established high voltage DC transmission (HVDC) technology as an alternative to long distance ac transmission.
Resources: OpenCourseware from NPTEL (India), Sheridan College, MIT, UC Berkeley, Stanford & many other of the World's finest University's
Professors: Michael Williams