500kV架空线直击和感应雷暂态过电压计算

Calculation of Transient Overvoltage Induced by Direct Lightning Flash and Lightning Induction along 500 kV Overhead Transmission Lines

目前中国大多省区已形成以特高压和超高压为骨干的输电网络,输电线路距离长、跨度大、分布广,所经过地域气象条件十分复杂,遭受各种雷电过电压的概率很高。通常将雷击过电压划分为直击和感应过电压,针对直击和感应过电压进行系统对比研究,对预防雷击事故、保障电网安全运行具有重要意义。将架空线等效为无限长载流导体,并在直击雷频域模型下采用ATP-EMTP建立500 k V架空线雷击瞬态响应模型,考虑多根导线的耦合关系,分别得出同塔双回和单回路杆塔上载流导线过电压波形及幅值。另一方面,利用Agrawal方程组建立了雷电电磁辐射模型,计算得出了雷击点附近线路上感应过电压。通过所计算结果,表明考虑线路耦合等多因素后,所得计算结果较经验公式计算结果偏低,符合实际情况。

At present, extra - high voltage and ultra - high vohage transmission grids have formed in most provinces of China. These transmission lines always have long distance, long span and wide distribution, and the weather condition is very complex where the transmission lines pass through. It is a high probability to be influenced by kinds of lightning overvohage. The comparative study of overvohage induced by direct lightning flash and lightning induction is carried out, which is of great significance to prevent lightning strike accidents and guarantee the safe operation. The overhead line is equivalent to an infinite con- ductor, and the transient response model is established under direct lightning flash frequency domain with ATP - EMTP. Con- sidering the coupling between multiple wires, the overvohage waveform and amplitude of double - circuit and single - circuit transmission lines are calculated. On the other hand, the lightning electromagnetic radiation model is established by using Agrawal equations, and the induced overvoltage on transmission lines near by the lightning strike spot is calculated. By com- paring the obtained calculation results with the results of empirical formula, it shows that the obtained calculation results is lower because of lines coupling and other factors, which conforms to the actual condition.