Method for calculating power cable real-time emergency carrying capacity

Abstract

The invention discloses a method for calculating power cable real-time emergency carrying capacity. The method includes the steps of firstly, establishing a cable system transient state thermal circuit model; secondly, establishing a heat balance equation; thirdly, obtaining a general solution of the heat balance equation; fourthly, obtaining the expression of the temperature of a conductor according to the initial condition; fifthly, converting the expression of the temperature of the conductor into the expression of the real-time emergency carrying capacity; sixthly, measuring or calculating the environment temperature and the temperature of the conductor at the initial moment; seventhly, determining the time of the N-1 fault repairing period or the time of the peak electricity consumption period and the limit value of the temperature of the cable conductor; eighthly, calculating real-time emergency carrying capacity of a cable. The method has the advantages that the maximum carrying capacity, namely, the real-time emergency carrying capacity, which enables the temperature of the cable conductor to rise to the limit value in a certain period of time is calculated, the scientific and reasonable decision foundation is provided for power grid dispatch and power line repairing in the emergency situation, and the calculation can be easily and conveniently conducted.

Description

technical field [0001] The invention relates to a calculation technology of the maximum ampacity during power cable operation, in particular to a calculation method of the real-time emergency ampacity of the power cable. Background technique [0002] With the development of the economy, more power cables are used in urban power grids for power transmission and distribution. Generally, the daily load characteristic of the power grid is a bimodal characteristic. Whether the power grid can bear the overload during the peak period and whether it needs to cut power depends on the carrying capacity of the line. According to statistics, the power grid operates at peak value for 2 to 3 hours. If the temperature of the cable conductor does not exceed 90°C during this period, the cable line can fully carry these loads without special operations. In addition, when an N-1 fault occurs on the cable line, whether the remaining lines can bear the full load or how much temporary emergency ...

AI Technical Summary

Problems solved by technology

These studies only focus on the calculation of overcurrent under short-circuit conditions, but there are few studies on other emergency situations, such as N-1 faults or power peak conditions. Once these situations occur, during the N-1 fault repair period or During the peak period of power consumption, the maximum current carrying capacity that the cable can withstand, that is, the real-time emergency current carrying capacity, is of great significance for power grid dispatching and power repair

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