ABSTRACT
The first high-voltage, direct current (HVDC) commercial transmission system was introduced in 1953. The cumulative megawatts of HVDC systems around the world approach 100 GW. The choice of ac transmission versus dc transmission depends upon the cost. For submarine cable, the ground electrodes are in the form of sea or shore electrodes. The three-phase converter transformers have, usually, grounded neutrals. Under normal operation, the rectifier maintains CC and the inverter maintains constant extinction angle (CEA) with adequate commutation margin to prevent commutation failure. The voltage-dependent current order limit (VDCOL) addresses the problems with under-voltage conditions. The schematics of equidistant firing control (EFC) are provided. Voltage converter-based HVDC, also called HVDC light, consists of a bipolar two-wire HVDC system with converters connected pole to pole. The IGBT valves comprise series connected IGBT positions. The complete IGBT position consists of an IGBT, an anti-parallel diode, a voltage divider, and water-cooled heat sink.
