Study on the voltage-sharing performance of porcelain insulators on 750kV compact double circuit transmission line

Having three-phase conductors arranged in inverted-delta mode in the same tower window,750 kV compact double circuit transmission line, which is built in China for the first time, has the seriously distorted voltage and electric field distribution of insulator strings, because of great mutual influence among three phases due to small phase spacing, so it is important to carry out the research on voltage-sharing performance of porcelain insulators on it. In this paper FEA (finite element analysis) method was utilized to calculate the distribution of voltage and electric field of porcelain insulators on 750 kV compact double circuit transmission line, and the mutual influence among three phases was considered. Meanwhile, the influence came from the conductors, tower and external environment was fully considered. By optimizing the structure parameters of grading ring, the influence, came from diameter, caliber and position of grading ring, on voltage distribution and electric field was calculated and analyzed. Based on the analysis above, reasonable configuration scheme of grading ring was proposed. Finally the calculation results were compared with the experimental ones, and the results showed the feasibility of FEA method in voltage distribution calculation of porcelain insulator strings, which provided evidence for the design of 750 kV compact double circuit transmission line.