Method considering influence of multiple factors for predicting fatigue life of large span power transmission wire

Abstract

A method considering influence of multiple factors for predicting fatigue life of a large span power transmission wire is disclosed; first, considering the influence of wind speed, ambient temperatureand current carrying capacity on the temperature of the wire, and calculating the actual temperature of the wire; then establishing a mechanical equilibrium equation of the power transmission wire, considering the influence of the temperature on the stress of the wire, and calculating the stress of a steel core aluminum strand of the wire under tension and temperature effects; using an energy method to establish an energy balance equation of the power transmission wire, and calculating the dynamic stress amplitude of the power transmission wire; calculating the equivalent alternating stress of the power transmission wire, and calculating the number of times of vibration resistance of the power transmission wire; calculating the annual vibration cycle number of the power transmission wireunder different frequencies according to the probability distribution of wind speeds and wind directions at each level; and finally, improving a traditional Miner method, considering the influence ofthe interaction between stresses of each level of the wire on the fatigue of the wire, and calculating and evaluating the fatigue life of the wire. The method for calculating the fatigue life of the large span power transmission wire is high in precision and high in speed, and is more in line with the engineering practice of the power transmission wire.

Description

technical field [0001] The invention relates to a method for predicting the fatigue life of a long-span power transmission conductor considering the influence of multiple factors, and belongs to the field of long-span power transmission engineering. Background technique [0002] Long-span overhead transmission lines have the characteristics of large spans, high suspension points, and complex operating environments. When subjected to the crosswind of 0.5m / s-10m / s, the leeward side of the transmission wire is prone to produce a stable Karman vortex, which makes the transmission line withstand the alternating up and down cyclic stress for a long time, which will cause fatigue of the overhead transmission wire and anti-vibration fittings Damage, and even cause the fatigue and broken strands of transmission wires, seriously affecting the safe operation of large-span transmission lines. Therefore, the prediction and calculation of fatigue life of transmission lines has become an ...

AI Technical Summary

Problems solved by technology

This calculation method has the following defects: First, it does not consider the influence of temperature changes caused by factors such as wind speed, ambient temperature, and ampacity on the average stress of the conductors.

The interaction between the stresses at different levels of the conductor under different wind speeds is not considered, and the influence of small loads below the fatigue limit stress is ignored

Therefore, the existing calculation method of conductor fatigue life based on Miner’s linear damage accumulation theory has large errors, which is not conducive to the anti-vibration design of overhead transmission lines. calculation method

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