DC systems with transformerless converters

Abstract

Abstrmt-A technical and economic feasibility study of HVDC systems without converter transformers is presented. The presentation includes proposed solutions to the drawbacks related to the absence of galvanic separation between the ac and dc systems, if the converter transformers are eliminated. The results show that HVDC systems without converter transformers are both technically and economically feasible. The cost savings can be substantial.

Power conversion systems for modern ac–dc power systems

“…The converter transformer produces most losses in the station, typically in the range of 40–50% of the overall losses, and it is considered as the most expensive component in the HVDC station . Table shows that a transformerless converter station provides significant savings in terms of cost and improves the station reliability and availability . A converter transformer, however, acts as a galvanic barrier between the ac and dc systems and mitigates the ac fault current imposed on the valves.…”

Flexible AC Transmission Systems (FACTS)

“…Recent considerations of using DC systems with transformer-less converters [38] indicate possible cost savings could result . These techniques could extend the range of applications for DC systems .…”