330kV绝缘子串电压分布和屏蔽环位置的优化

为计算330kV线路绝缘子串电压分布和优化屏蔽环的位置,建立了考虑屏蔽环、分裂导线、杆塔、联板、悬垂线夹和其它连接金具的三维静电场有限元模型。计算并讨论了带和不带屏蔽环、带和不带联板的绝缘子串电压分布以及屏蔽环位置变化对电压分布的影响。结果表明,导线和杆塔侧绝缘子承受较高电压,屏蔽环可有效改善其附近绝缘子上承受的电压,理论上有一最优位置;导线侧金具对电压分布影响较大,计算模型中应考虑。

Calculation of Voltage Distribution Along Insulator String of 330 kV Transmission Line and Position Optimization of Grading Ring

Supporting conductors and insulation are the main functions of insulator string of transmission line, and the insulator stable operation is very important to the power system stability. Voltage is very irregularly distributed along insulator string with the AC high voltage. First insulator of glass, porcelain insulator string and composite insulator string nearby conductors has high voltage, and this high voltage does harm to the insulator's operation. Voltage distribution along transmission line's insulator string is related to the type and number of insulator, grading ring's position and the selection of hardware fittings' configuration. So, voltage distribution along insulator string is very important to insulator design, operation and maintenance. Grading ring is necessary to uniform the voltage distribution along insulator string, and the uniform effect is related to the type and position. The study on voltage distribution along insulator string and position of grading ring is beneficial to insulator's stable operation. Experiments of voltage distribution along insulator string have many disadvantages, such as great workload, long working period and high costs, while, numerical calculation method can deal with these disadvantages and calculation results can satisfy the precision requirements of practical engineering. Finite element method (FEM) is applied to the calculation of voltage distribution along insulator string of a 330 kV transmission line,and the results are applied to position optimization of grading ring. 3D electrostatic model is established; grading ring, bundle conductors, tower, yoke plate, suspension wire clips and other hardware fittings are considered, suitable exterior boundary length is selected too, which ensure the precision of calculation results. The voltage distribution of insulator string with and without grading ring, with and without yoke plate is calculated and compared; and the influence of grading ring's position variation on voltage distribution is discussed too. It can be found that hardware fittings nearby conductors and the position of grading ring influence the calculation result greatly, it is necessary to consider hardware fittings in the calculation model,and the grading ring has an optimal position in theory.