Study On The Natural Contamination Characteristics Of Insulators On UHVDC Transmission Line

Insulator natural contamination characteristics are the important reference to the amendment of relative standards and the design, operation and maintenance of electrical equipment external insulation. UHVDC transmission project has the features of high voltage level and complex transmission environment, and its external insulation design is a hot topic in recent years. However, due to the lack of operating experience of UHVDC transmission project, the researches at home and broad on the natural contamination characteristics of UHVDC line insulators are relatively few.Based on the Henan Province section Hamilton South to Zhengzhou UHVDC transmission line, the natural contamination test has been designed. The program discuss four areas in detail, which are sampling protocol tower selection, test insulator installation, test cycle, the test content & test methods. In addition to the general test items of insulator surface contamination, this test will also determine the chemical composition of the contamination as an important content.Based on the insulator natural contamination depositing tests of the Henan segment of Ha-Zheng UHVDC transmission line, the datum and change rules of UHVDC negative line insulator surface contamination in this area are analyzed. Besides, the contamination depositing differences among the uncharged insulators at different heights on the same tower and at similar height on the UHVDC tower is analyzed. According to the surface contamination component test datum of negatively charged insulators, combined with the enrichment factor method, the impact of pollution around the tower on the contamination of insulators is analyzed.In order to compare the natural contamination characteristics rules of UHVDC line insulator and UHVAC line insulator, the natural contamination test has been carried out in the parallel section of UHVDC and UHVAC transmission lines in Henan. The salt density ratios of DC insulator and AC insulator were obtained, the NSDD ratios were also gotten. Moreover, compared to of UHVAC transmission line insulator in the same region, the upper and lower surface contamination of UHVDC transmission line insulator is more uneven. Electric power and rainfall led to this phenomenon together.