The single-active-part structure of the UHVDC converter transformer with the UHVAC power grid

Abstract

The studied sending-terminal's UHVDC converter transformer with the UHVAC grid is currently one of the largest-capacity converter transformers, which is characterized by strong support for the large-scale grid power delivering out, strengthening grid's fault tolerance and backup capability, improving grid operation's flexibility and security, lowering the short-circuit currents. The proposed single-active-part converter transformer structure is well-designed, including the single-phase five-leg iron core, the special winding arrangement, the special structure of the spacers and angle rings, and so on, which is a smaller footprint, easier to install and test on site, but is more challenging in the structural design due to the critical railway transportation limitations on aspects of both size and weight. The feasibility of the proposed structure schema is verified by a series of tests, concerning the wave process, the short circuit force, the temperature field, the main insulation, and so on. Among them, the main insulation's electric fields at the import positions are verified to be reasonable, including the AC impressed voltage test, the DC impressed voltage test, and the polarity reversal test. It shows that the proposed single-active-part design scheme is practicable and conductive to manufacture and application for the UHV large-capacity converter transformers.