Application Of Composite Insulators Technology In Lanzhou Power Network

This thesis is based on the reconstruction project of strain tower insulator string in the Lanzhou power company. In order to improve the wiring insulation, the insulator electric arc distance for the Lanzhou power company is required up to 1200 mm through improving the 110 kV overhead transmission line's outer insulation. But the long distance of electric arc means the composite insulators structural height would be increased. Compared to the original plan of the insulator, to replace the new insulators would cause excessive relaxation in the wire on both sides of strain towers, and then the insulation distance between phase to phase and phase to ground would to be inadequate. If demanding the wire's relaxation is unchanged, the method of truncating strain tower connection hardware and reconnect the wire could be adopted. But this method would not only greatly add the amount of construction work, but also raise the effects of the connection hardware on the wire relaxation, and even change the mechanical strength of the wire and the forces for tower arm further. To achieve the purpose of the transformation, it is required to adopt the new composite insulators whose structure length remain the same and electrical properties also meet the requirements. The main task of this thesis is to analyze the applicability of composite insulators selection.Firstly, the usage of the composite insulators in Lanzhou area and the connection method of composite insulators in tension tower are introduced in this thesis. The mechanical properties of composite insulators for strain tower are analyzed. Through analyzing the operating environment of external insulation equipment at Lanzhou, the creepage distance method for insulation configuration is considered to adopt, and the insulator configuration is analyzed by combing with the method of fouling resistance voltage. At last, the relationship between the shed structure and the creepage distance and the influence of the shed structure to flashover voltage are all studied. Considering the affecting factors of this area atmospheric environment, the experiment analysis of the electrical performance for different shed structure composite insulators is achieved. Moreover, the selection criteria for composite insulators is obtained. When the composite insulators remain the same of its highly original structure, the composite insulator could meet the requirements of the level D and E polluted area level grade and the requirements of electrical, mechanical and chemical in Lanzhou atmospheres.At present, the rationality of the design scheme proposed in the thesis is confirmed, and the anticipated goal of the research is achieved by tracking the application of the composite insulators in Lanzhou.