1000kV特高压交流复合绝缘子耐张串均压特性研究

Study on Optimization Characteristic of Composite Tension Insulators for 1000 kV UHVAC Lines

交流电压作用下,由于复合绝缘子导线侧和杆塔侧的杂散电容不同,绝缘子的沿串电压分布不均匀。采用三维有限元方法分别计算了特高压交流1 000 kV单回和双回输电线路一字型4联550 kN复合绝缘子耐张串的沿面电位和电场分布,比较了大环屏蔽深度、管径、外径等均压环结构参数对电场分布的影响,给出了均压环的推荐配置方案。结果表明,当中相施加相电压峰值时,各关键部位场强值最大;单回和双回耐张串均压环表面最大场强分别为2.06 kV/mm和1.8 kV/mm,绝缘子伞裙护套表面最大场强分别为0.33 kV/mm和0.31 kV/mm,满足均压环表面场强在峰值下不超过2 kV/mm,复合绝缘子伞裙护套表面场强在有效值下不超过0.4 kV/mm的电场控制要求。

Due to the different stray capacitance at conductor and grounding top of composite insulators under AC voltage, the electric potential distribution along the insulators is un-uniform. The three-dimensional finite element method is used to calculate the potential distribution and electric field distribution of line-shape 4~550 kN composite tension insulators for 1 000 kV UHVAC transmission lines, where single and double circuit is calculated respectively. The impacts of structural parameters of grading ring, including shielding depth, ring diameter and tube diameter, on the distribution of electric field are compared and a recommended configuration scheme of grading ring is suggested. Calculation results show that when peak phase voltage is applied to the middle phase, the electric field strengths at key positions reach to their maximum; on single circuit 1 000 kV transmission line, the maximum electric filed strength on grading ring surface and insulator surface are 2.06 kV/mm and 0.33 kV/mm respectively, while they are 1.8 kV/mm and 0.31 kV/mm of double circuit 1 000 kV transmission lines respectively. All the calculation results under the suggested grading ring configuration meet the electric filed requirements, which are 2 kV/mm on grading ring surface under peak phase voltage and 0.4 kV/mm on insulator surface under effective value.