考虑后续回击的500 kV单回交流线路耐雷水平研究

Study on Lightning Resistance Level of 500 kV Single Circuit AC Transmission Line Considering Subsequent Lightning Return Stroke

雷电严重威胁着电力系统的安全稳定运行,随着电力系统的不断发展,传统的线路防雷评估技术已无法满足目前线路的雷击风险评估需求.基于此,本文利用变异系数法对华中区域十条500 kV省间联络线重要输电通道10 km范围内近年来的落雷数据进行分析,发现后续回击会对线路的雷击跳闸率产生较大影响,同时多起线路实际雷击跳闸故障与后续回击相关.据此,本文在传统绝缘子串闪络模型的基础上,提出了考虑后续回击的绝缘子串闪络判据模型,分析考虑后续回击的500 kV重要输电通道的线路耐雷水平.研究结果表明:后续回击会使500 kV输电线路的耐雷水平降低,降低程度与工频电压周期有关,且后续回击对反击耐雷水平的影响程度与绕击耐雷水平相比更为显著.本文的研究结论可以辅助提升高压输电线路的雷击风险评估准确度,为高压输电线路防雷预警提供帮助.

Lightning seriously threatens the safe and stable operation of power system. With the continuous development of power system, the traditional line lightning protection assessment technology has been unable to meet the requirements of lightning risk assessment. Based on this, this paper uses the coefficient of variation method to analyze the data of lightning falling in recent years within 10 km of ten important transmission channels of 500 kV inter-provincial connection lines in central China, and finds that subsequent lightning return strokes have a great impact on lightning strike trip. At the same time, many circuit actual lightning trip faults are related to subsequent lightning return strokes. Accordingly, this paper proposes a flashover criterion model of insulator string considering subsequent return stroke. The influence of subsequent lightning return stroke on lightning resistance level of 500 kV transmission lines is analyzed. The results show that the lightning resistance level of 500 kV transmission line will be reduced by the follow-up return stroke, which is related to the power frequency voltage cycle, and the impact of the subsequent lightning return stroke on the lightning back-flashover resistance level is more significant than the lightning shielding resistance level. The conclusion of this paper can help improve the accuracy of lightning risk assessment of high-voltage transmission lines and provide help for lightning protection and early warning of highvoltage transmission lines.