改善杆塔波阻抗对110kV输电线路雷击过电压的影响

Influence of Reducing Tower Wave Impedance on Lightning Overvoltage of 110 kV Transmission Line

杆塔波阻抗是引起输电线路发生反击闪络的一个重要因素。本研究从降低杆塔波阻抗的角度出发,提出了增设拉线减小杆塔波阻抗,进而提升线路耐雷水平的方法,并建立了拉线、杆塔、输电线路、绝缘子、避雷器EMTP仿真模型,研究了工作电压、拉线、接地电阻、避雷器安装方式对线路耐雷水平的影响,以及拉线与避雷器相互配合的防雷效果。结果表明:线路耐雷水平受工频电压相位角影响,近似呈现余弦变化,但整体变化幅度较小,在电压相位角为180°时,输电线路耐雷水平处于最低值;在低接地电阻区域,拉线可以代替避雷器有效提升线路耐雷水平,且拉线数量越多,效果越显著,而雷害严重时可以采用拉线配合避雷器进一步提升线路耐雷水平;对于高接地电阻区域,仅采用拉线改善杆塔波阻抗的方法效果有限,可通过局部安装避雷器的方法提升线路耐雷水平,其中方式12效果最优。

Tower wave impedance is an important factor that causes flashback of transmission lines. From the point of view of reducing the wave impedance of the tower, the author puts forward the method of adding stay wire to reduce the wave impedance of the tower and then improving the lightning resistance level of the line. And EMTP simulation models of stay wire, tower, transmission line, insulator and arrester are established. Then, the influence of working voltage, stay wire, grounding resistance, installation mode of arrester on the lightning resistance level of the line, and the lightning protection effect of the coordination of stay wire and arrester are studied. The results show that: the lightning resistance level of transmission line is affected by the phase angle of power frequency voltage, approximately showing cosine change, but the overall change amplitude is small. When the phase angle of voltage is 180 degrees, the lightning resistance level of transmission line is at the lowest value;in the area of low grounding resis-tance, the guy wire can effectively improve the lightning resistance level of the line instead of the arres-ter, and the more the number of the guy wire, the more significant the effect, and when the lightning damage is serious, the guy wire and arrester can be used to further improve the lightning resistance level of the line. For the area with high grounding resistance, the method of only using guy wire to improve the wave impedance of tower is limited, and the method of installing lightning arrester locally can improve the lightning resistance level of the line, of which the effect of mode 12 is the best.