A Study on Progress of Accuracy in Estimation of Sparkover Rate of Medium-Voltage Line

中压线路跳火率估算精度的研究进展

• 批准号: 13650302
• 负责人: MICHISHITA Koji
• 金额: $ 2.3万
• 依托单位: Shizuoka University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2001
• 资助国家: 日本
• 起止时间: 2001 至 2003
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13650302/
• 关键词: Lightning; Medium-Voltage Line; Direct Stroke; Lightning-Induced Voltage; Surge Arrester; Insulator; Sparkover Rate; Overhead Ground Wire; 帰還雷撃; フラッシオーバ率; 電界; 磁界; 雷被害率

A model of a pole-type transformer is developed by taking account of resonance, and the insulation characteristics of a solid-core insulator are investigated. In the analysis of the sparkover rate of a medium-voltage line, it is recommended that a model of a transformer developed by taking account of resonance is used. For the accurate estimation of the sparkover rate, it is better to take account of V-t characteristics of the insulator for steep-front and short-tail lightning impulse, however, the 50% sparkover voltage for the impulse might be reasonable criteria for the estimation since calculation by using the V-t characteristics is time-consuming. The sparkover rate of the line over lossy ground caused by an indirect stroke is more than 10 times higher than that over perfectly conducting ground. The sparkover rate due to a direct stroke to the line is more than 10 times higher than that due to an indirect stroke even when the line is over lossy ground. Therefore, it is confirmed that the sparkover associated with a direct stroke to the line is more frequent than that associated with an indirect stroke. The fact that the estimated sparkover rate is 10 times higher than the practical rate indicates the necessity of the further study on the striking distance and the mechanism of the outages. The waveform parameters of negative strokes of natural lightning estimated based on measured electric field waveforms are in good agreement with those evaluated from direct measurement of the current waveform. This infers the possibility that that the return stroke current parameters including the parameters on wave tail can be estimated from the electric field measurement.

建立了考虑谐振的极型变压器模型，研究了实心绝缘子的绝缘特性。在分析中压线路的火花击穿率时，建议采用考虑谐振的变压器模型。为了准确估计闪蒸率，最好考虑陡前和短尾雷击时绝缘子的V-t特性，但由于使用V-t特性计算比较耗时，因此该脉冲的50%闪蒸电压可能是合理的估计标准。线路在有损耗的地面上由间接冲击引起的火花率比在完全导电的地面上高10倍以上。即使线路在有损耗的地面上，直接冲击线路所引起的火花率也比间接冲击线路所引起的火花率高10倍以上。因此，可以肯定的是，与直接冲程相关的火花比与间接冲程相关的火花更频繁。估计的电火花率是实际电火花率的10倍，这表明有必要进一步研究电火花击穿距离和停电机理。根据实测电场波形估计的自然闪电负冲程波形参数与直接测量电流波形的结果吻合较好。由此推断，从电场测量中可以估计出包括波尾参数在内的回冲电流参数的可能性。

项目成果

K.Michishita, M.Ishii, A.Asakawa, S.Yokoyama, K.Kami: "Voltage induced on a test distribution line by negative winter lightning strokes to a tall structure"IEEE Transaction on Electromagnetic Compatibility. Vol.45,No.1. 135-140 (2003)

K.Michishita、M.Ishii、A.Asakawa、S.Yokoyama、K.Kami：“冬季负雷击对高层结构在测试配电线上感应的电压”IEEE 电磁兼容性交易。