Application of GTO voltage source inverter in a hybrid HVDC link

This paper investigates the application of a GTO voltage source inverter in a two-terminal HVDC link, which is fed at the sending end by a line-commutated rectifier. This type of HVDC link may be applied when power transfer is predominantly unidirectional, especially to a weak AC system. The investigations are based on analytical studies and digital time-domain simulations with the Electromagnetic Transient program for DC systems (EMTDC). Control method and protection requirements are studied, together with dynamic behavior of the system following disturbances, e.g. DC fault, AC fault, start-up etc. The studies are aimed at exhibiting the technical feasibility of the proposed HVDC scheme. Need for further studies is pointed out when necessary