Method for measuring thunderbolt shielding failure of overhead power transmission line under condition of unequal heights of both span ends

Abstract

The invention discloses a method for measuring a thunderbolt shielding failure of an overhead power transmission line under the condition of unequal heights of two span ends, comprising the following steps of: firstly, measuring relevant parameters of the transmission line with the thunderbolt shielding failure to be measured; secondly, determining the projected area of an exposed cambered surface; thirdly, determining the projected area of a lightning-stroke cambered surface; and fourthly, determining the thunderbolt shielding failure. The method overcomes errors generated by the traditional method for calculating by adopting the average height of conducting wires and can be used for lightning-protection estimation and design of transmission lines in complicated terrains and districts, thereby saving the lightning-protection construction expenses of the transmission lines.

Description

Technical field [0001] The invention relates to a method for measuring the lightning shielding rate of a transmission line, in particular to a method for calculating the shielding probability of a transmission line when the conductors at both ends of the span of an overhead transmission line are not equal in height, and belongs to the field of overvoltage and insulation coordination. Background technique [0002] Power outages caused by lightning strikes on overhead transmission lines are the main cause of unplanned power outages. In order to evaluate and design the lightning protection performance of overhead transmission lines, it is often necessary to determine the probability of the lightning shielding conductor of the transmission line, referred to as the lightning shielding rate. At present, the methods for measuring the lightning shielding rate of transmission lines mainly include the rule method, the electrical geometric model method, and the pilot method. Among the...

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Problems solved by technology

Among them, the regulation method believes that the shielding rate has nothing to do with the magnitude of the lightning current amplitude, and the consideration of the terrain is only distinguished by mountainous areas and flat areas; the leader method believes that lightning strikes occur due to the encounter between the downlink lightning leader and the uplink leader produced by objects on the ground , is related to the lightning current amplitude and the height of the structure, but the calculation is complicated; the electric geometric model method based on the concept of striking distance believes that the shielding tripping rate is related to the lightning current amplitude and the structural object struck by lightning, and the calculation is usually Bring the average height of the wires into the formula of the electrical geometric model method for calculation

However, the actual transmission line often passes through mountains, hills and other terrains, and it is very rare that the wires at both ends of the span are of the same height. The unequal height of the conductors will cause a large error, and it is difficult to truly reflect the lightning shielding rate of the transmission line, which will affect the lightning protection evaluation and design of the complex terrain of the transmission line, resulting in a lightning strike failure ratio design during the operation of the transmission line. The higher the value, the higher the proportion of lightning faults to unplanned outages

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