圆环形接地体与人字形接地体的冲击特性量化比较

Quantitative Comparison of Impact Characteristics Between Circular Grounding Body and Herringbone Grounding Body

为深入研究不同形状接地体的冲击特性差异,指导输电线路杆塔的接地设计,笔者分别对圆环形接地体与人字形接地体进行研究。先利用CDEGS软件,对二者进行建模仿真,通过正反傅里叶变换,得到其各自的时频域冲击特性响应,再进行量化比较。结果表明:当土壤电阻率为200Ω·m时,圆环形接地体的冲击接地电阻、地电位升高、跨步电压均高于相同周长下人字形接地体;而当土壤电阻率为1200Ω·m时,圆环形接地体的冲击接地电阻、地电位升高、跨步电压均低于相同周长下人字形接地体。当入地电流频率低于10kHz时,两种接地体的接地阻抗值与频率变化基本无关,且两种接地体的接地阻抗角始终小于10°。当入地电流频率高于10kHz时,两种接地体的接地阻抗值和接地阻抗角都随频率上升而迅速增大,且人字形接地体的接地阻抗值与接地阻抗角增长更快。现场测试结果与仿真结果一致。

In order to deeply study the impact characteristics of different shapes of grounding bodies and guide the grounding design of transmission line towers,the circular grounding body and herringbone grounding body are studied.Firstly,the CDEGS software is used to model and simulate the two,and obtain their respective time-frequency domain impulse response through forward and reverse Fourier transform.Then carry out quantitative comparison.The results show that when the soil resistivity is 200Ω·m,the impulse grounding resistance,ground potential rise and step voltage of circular grounding body are higher than those of herringbone grounding body under the same perimeter;when the soil resistivity is 1200Ω·m,the impulse grounding resistance,ground potential rise and step voltage of the circular grounding body are lower than those of the herringbone grounding body under the same perimeter.When the frequency of grounding current is lower than 10kHz,the grounding impedance values of the two grounding bodies are basically independent of the frequency change,and the grounding impedance angle of the two grounding bodies is always less than 10°.When the frequency of grounding current is higher than 10kHz,the grounding impedance value and grounding impedance angle of the two grounding bodies increase rapidly with the increase of frequency,and the grounding impedance value and grounding impedance angle of herringbone grounding body increase faster.The field test results are consistent with the simulation results.