HVDC converter

An HVDC converter converts electric power from high voltage alternating current (AC) to high-voltage direct current (HVDC), or vice versa. HVDC is used as an alternative to AC for transmitting electrical energy over long distances or between AC power systems of different frequencies.[1] HVDC converters capable of converting up to two gigawatts (GW)[2] and with voltage ratings of up to 900 kilovolts (kV)[3] have been built, and even higher ratings are technically feasible. A complete converter station may contain several such converters in series and/or parallel to achieve total system DC voltage ratings of up to 1,100 kV.

Symbol for HVDC converter

Almost all HVDC converters are inherently bi-directional; they can convert either from AC to DC (rectification) or from DC to AC (inversion). A complete HVDC system always includes at least one converter operating as a rectifier (converting AC to DC) and at least one operating as an inverter (converting DC to AC). Some HVDC systems take full advantage of this bi-directional property (for example, those designed for cross-border power trading, such as the Cross-Channel link between England and France).[4] Others, for example those designed to export power from a remote power station such as the Itaipu scheme in Brazil,[5] may be optimised for power flow in only one preferred direction. In such schemes, power flow in the non-preferred direction may have a reduced capacity or poorer efficiency.

  1. ^ Arrillaga, Jos; High Voltage Direct Current Transmission, second edition, Institution of Electrical Engineers, ISBN 0852969414, 1998, Chapter 1, pp 1-9.
  2. ^ Davidson, C.C., Preedy, R.M., Cao, J., Zhou, C., Fu, J., Ultra-High-Power Thyristor Valves for HVDC in Developing Countries, IET 9th International Conference on AC/DC Power Transmission, London, October 2010.
  3. ^ Skog, J.E., van Asten, H., Worzyk, T., Andersrød, T., Norned – World's longest power cable, CIGRÉ session, Paris, 2010, paper reference B1-106 Archived 2015-09-23 at the Wayback Machine.
  4. ^ Rowe, B.A., Goodrich, F.G., Herbert, I.R., Commissioning the Cross Channel h.v.d.c. link, GEC Review, Vol. 3, No. 2, 1987.
  5. ^ Praça, A., Arakari, H., Alves, S.R., Eriksson, K., Graham, J., Biledt, G., Itaipu HVDC Transmission System - 10 years operational experience, V SEPOPE, Recife, May 1996.