A Calculation Method for the Trip Rate of 35kV and Below Distribution Lines Directly Struck by Lightning

Abstract

The invention relates to a method for calculating the direct lightning tripping-out rate of a distribution line up to 35kV. In the method, firstly, the lightning damage condition of the region where the distribution line is arranged, and the line parameters and the tower parameters are obtained, and the probability of the event that the lightning current hits the towers and the probability of the event that the lightning current hits the wires are obtained. Secondly, in view of the special neutral point grounding manner of the distribution line, when the lightning current directly hits wires, and two phase flashover and three phase flashover of insulators occur, and the amplitude of the lightning current is calculated through a brand new formula. the simulation model that the lightning current hits towers and lightning conductors under the condition of a specific tower shape and a specific loop is established by means of electromagnetic transient simulating calculation software, the amplitude of the lightning current which causes two phase flashover and three phase flashover of the insulators is obtained, furthermore, the straight hit tripping-out rate is calculated through a new formula, the back flashover tripping-out rate is calculated through a new formula, and by adding the straight hit tripping-out rate to the back flashover tripping-out rate, the total straight hit tripping-out rate can be obtained. The method for calculating the direct lightning tripping-out rate of the distribution line up to 35kV is suitable for calculating the tripping-out rate of the distribution line under the condition of different tower shapes and loops, and can provide basis to lightning damage assessment and line reconstruction.

Description

technical field [0001] The invention relates to the field of lightning damage level evaluation and protection of distribution lines, in particular to a method for calculating the tripping rate of direct lightning strikes on distribution lines of 35kV and below. Background technique [0002] The power distribution line is the level closer to the user in the power system. It is responsible for the important responsibility of supplying power to industrial and agricultural production and residents' daily life. It has the characteristics of complex line structure, large number of lines, and wide coverage area. In the past, the idea of ​​focusing on the main network and ignoring the distribution network existed for a long time, resulting in a large gap between the equipment status and technical level of the current distribution network compared with the main network. The insulation level of distribution lines is low, and there are generally no special lightning protection measures...

AI Technical Summary

Problems solved by technology

In the past, the idea of ​​focusing on the main network and ignoring the distribution network has existed for a long time, resulting in a large gap between the equipment status and technical level of the current distribution network compared with the main network.

The insulation level of distribution lines is low, and there are generally no special lightning protection measures. Not only are they affected by direct lightning strikes, but also insulator flashovers occur due to the influence of induced overvoltages generated by lightning strikes on the ground.

Compared with high-voltage transmission lines, distribution lines are more prone to lightning flashover tripping, which seriously affects the reliability of power supply

[0003] At present, the focus of lightning protection research on domestic power grids is mainly concentrated on the main network. Due to the low voltage level of the distribution network, related lightning protection research issues have not been paid attention to, and the overall lightning protection research on the distribution network is relatively weak.

Overvoltage reaching a certain level may cause line tripping, affect the safe and stable operation of distribution lines, and adversely affect residents' lives and social production

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