Breakdown Characteristics of Oil-Paper Insulation in UHVDC Converter Transformer Under AC/DC Voltage and Its Selection of Oil and Paper

Abstract

s the core equipment of UHVDC system, the UHVDC converter transformer of home manufacture will be significant to the development of UHVDC technology. According the complicated operation condition of UHVDC converter transformer and the compound voltage breakdown characteristics of different oil-paper combinations, this article researches the selection work of oil and paper. The results show that the breakdown voltage of oil declines smoothly with the decrease of AC voltage components, while the breakdown strength of oil-impregnated paper increases rapidly and the insulation performance of oil-paper is mainly decided by the paper instead of oil. Meanwhile, consider the distribution characteristics of AC and DC voltage in the oil-paper insulation and based on the valve and line side of UHVDC converter transformer, this paper analyzes the factors which will influence the selection work. Finally, according the results that KI-50X oil and DPE paper are the best choice. In a word, this paper can provide some relevant reference dates to the manufacture of UHVDC converter transformer.