Identification method of cable current-carrying capacity and identification device

Abstract

The invention relates to an identification method of cable current-carrying capacity and an identification device; after relative performance parameters of the cable are measured, the temperature endvalue of the conductor is calculated by setting current initial value of the conductor and the temperature initial value of the conductor, and the temperature initial value of a conductor is correctedaccording to the difference of the temperature end value and the temperature initial value of the conductor, until the difference of the two-time conductor temperature is less than a first presettingdeviation range, at the moment, the temperature end value of the conductor is the conductor temperature under the action of the current initial value of the present conductor; the current initial value of the conductor is continuously corrected according to the difference of the temperature end value of the conductor and 90 (the highest insulating working temperature of XLPE), until the absolutedifference of the temperature end value of the conductor and 90 is less than a second deviation range, the current initial value of the conductor, corresponding to the end value of the conductor temperature, is determined into the final cable current-carrying capacity. By initializing the value of the conductor current and temperature and adopting an iteration process which is continuously carriedout, the problem that the obtained result in the existing method is inaccurate, so as to determine the cable current-carrying capacity accurately.

Description

technical field [0001] The invention relates to the field of electric power technology, in particular to a method for determining the ampacity of a cable and a device for determining the ampacity of a cable. Background technique [0002] The 100% load factor ampacity of the cable (referred to as the cable ampacity) is one of the most important parameters in the cable line. The accurate calculation of the cable ampacity is important for both the design of the power cable and the operation of the power system. Significance, which is usually reflected in: the power design department selects the cable type and cable line design according to the cable ampacity, while the power operation department controls the load of the cable line according to the cable ampacity, so the calculation of the cable ampacity The determination method plays an important role in the operation of the entire power system. [0003] Considering that the long-term allowable maximum working temperature of t...

AI Technical Summary

Problems solved by technology

After calculation, for a cross-sectional area of ​​630mm 2 For the copper conductor of the cable, when the conductor temperature drops from 90°C to 80°C, the conductor resistance will decrease by 3.1%. It can be seen that the influence of the temperature coefficient on the copper conductor resistance cannot be ignored. If the right side of the equation (3) is combined with the conductor temperature-dependent terms, including W c , lambda 1 , lambda 2 and so on, are calculated by using 90°C or estimated values, which will inevitably lead to large errors. On the other hand, if the parameters related to the conductor temperature in formula (3) are expressed as a function of the conductor temperature and sorted out, The result will be a very complex expression, it is difficult to realize the analytical calculation of the cable conductor temperature, and the complexity is high, which in turn brings complexity to the calculation of the cable current carrying capacity

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