Experiment Study On Oil-flow Electrification Of Typical Insulation Under Combined AC-DC Electric Field Of Converter Transformer

With the developing highly of HVDC transmission project, the application ofHVDC transmission system in far distance of transmission in China is increasing,and the security and stability of converter transformer is more and more concerned.According to practical requirement and the applied field characteristic of convertertransformer insulation, this article launched the work of oil-paper insulation flowelectrification under AC-DC field, in order to analyze comprehensively oil-flowelectrification characteristic and regular pattern of oil-paper insulation under AC-DC field.According to research and trend of oil-flow electrification in convertertransformer currently, this article analyzed formation process and mechanism ofoil-paper insulation and its mathematical model of oil-paper insulation flowelectrification and influencing factors; and then designed the tentative system ofoil-paper insulation flow electrification、founded AC-DC tentative equipment、elaborated pretreatment method of materials、measurement grounds and methodof streaming current; finally analyzed and summarized oil-flow electrificationtendency regular pattern on effect of factors under AC-DC field.The experiment result showed that oil-flow electrification tendency increasesas veloticy improves under DC field and AC-DC field; oil-flow electrificationtendency under field is higher than tendency without field. Oil-flow electrificationtendency increases as voltage amplitude improves, and increases as DCcomponent improves; oil-flow electrification tendency increases first anddecreases next as temperature improves.Study of oil-paper insulation flow electrification provided theory and datasupport for the restraining of streaming current, and have important practicalsignificance to the security and stability of converter transformer.