The Study Of Icing Composite Insulators' Configuration Characteristics Based On Electrical Field Distribution

Icing poses a great threat to safe operation of power system. Compared with traditional ceramic and glass insulators, composite insulators have the advantages of less weight, higher strength, more excellent anti-contaminated characteristic, and easier to be maintained. Consequently, it is widely used by power utilities in many iced areas. Icing influences the distribution of electric field and potential greatly because of the short sheds and height of sheds. Therefore, it is significant to study the impact of icing and arc on the distribution of electric field and potential.Based on the asymptotical boundary condition, open domain problem is transformed into a finite domain one, and finite element method is adopted to calculate the distribution of surface electric field and potential of composite insulator. By using the software FEMLAB, iced composite insulator in 220kV is analyzed and, as a consequence, distribution of electrical field and potential under the condition of icing and post-arcing are obtained respectively.The electrical field mathematical model of composite insulators in two-dimension axial symmetry is established; The author calculates distribution of electric field and potential under three cases: both the high voltage and grounding end with and without corona ring, and only the high voltage end with corona ring. For composite insulators of 220kV and above grade, installation of corona ring has great effect to improve the distribution of electrical field and potential of composite insulators; The author researches the influence of the length of icicle in ice bridge connection and the position of air gap in the composite insulators to the distribution of electrical field and potential. The result indicates the icicle of composite insulators makes the distribution of electrical field and potential extraordinary non-uniform, and the different position of air gap in icicles has different influence to the distribution of electrical field and potential. The water film further aggravates distortion of the distribution of electrical field and potential along iced composite insulators, the flashover voltage in wet icing is much lower than the flashover voltage in dry icing; The author analyses the relationship between the distribution of electrical field and potential and big shed diameter, space distance of two sheds and, obtains the appropriate corona ring installation site.