Bushings are the key equipment in a high voltage direct current (HVDC) project. During this webinar, we will illustrate the theory of electric field adaptive grading in high voltage equipment by using nonlinear materials at first. Then, the nonlinear material, ZnO microvaristors-based composites, adopted in the HVDC bushing is introduced. The source and the adjusting methods for the nonlinear conductivity of the composite have also been discussed. Thirdly, the structure and the electric field distribution in the traditional bushing and the bushing with electric field adaptive grading structure are compared to highlight the advantages of the electric field adaptive grading structure. At last, the prototypes of a ±100 kV transformer bushing and a ±200 kV wall bushing are presented.

Presented by: Zhikang Yuan, Tongji University, China