摘要
杆塔接地装置的冲击电阻是影响输电线路耐雷水平的重要参数之一,研究接地装置的冲击特性对输电线路的雷电防护具有重要意义。高幅值雷电流作用下,接地装置周围土壤会发生火花放电,使得其冲击特性与工频特性有显著的区别。为解决频域电路理论在对雷电流和响应电压进行傅里叶变换过程中需要忽略掉大量高频分量的问题,该文建立了考虑土壤火花放电的接地装置暂态特性全时域电网络模型。针对低阶精度时域差分法计算得到的响应电压存在局部锯齿状波形的问题,推导出了电网络模型的p-order精度时域差分解。结果表明,(3~5)-order精度时域差分法计算得到的响应电压波形平滑没有波动,能够提高计算精度,并减少计算时间。在武汉特高压试验基地对杆塔接地装置进行了大电流冲击试验,验证了该仿真算法的准确性。
The impulse resistance of the tower grounding devices is one of the key factors that affect the lightning withstand level of the transmission lines. Therefore, study of the impulse characteristics of grounding devices is important for the lightning protection of transmission lines. The sparkover occurs in the soil around the grounding devices under the lightning current of high-amplitude. It makes the impulse characteristics of grounding devices strikingly different from its power-frequency characteristics. The frequency-domain circuit theory had to ignore a large number of high-frequency components during Fourier transformation process of lightning current and response voltage. In order to solve this problem, the time-domain electrical network model of the transient characteristics of grounding devices considering soil sparkover was established in this paper. In order to solve the problem that the response voltage calculated by the low-order time-domain difference method had local zigzag waveforms, the difference solution of p-order accuracy of the proposed model was derived in time domain. The waveform of the response voltage calculated by the time-domain difference method of(3~5)-order accuracy was smooth. It could improve the precision and reduce the computing time. The large current tests of the tower grounding devices were carried out in Wuhan Ultra-High Voltage Test Base. The accuracy of the proposed simulation method is validated by those experiments.
引文
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