Calculation method for power cable emergency load carrying capacity

Abstract

The invention discloses a calculation method for power cable emergency load carrying capacity. The calculation method includes the following steps that 1, alternating-current resistor R, environment temperature t0, conductor temperature T1, insulating layer temperature Tn-3, buffering strip temperature Tn-2, aluminum sheath temperature Tn-1 and outer sheath temperature Tn when a circuit fails in a power cable are calculated, the alternating-current resistor R is calculated through an alternating-current resistor formula, the environment temperature t0 is obtained through online monitoring, the conductor temperature T1, the insulating layer temperature Tn-3, the buffering strip temperature Tn-2, the aluminum sheath temperature Tn-1 and the outer sheath temperature Tn are obtained through calculation according to a cable transient state thermal circuit model, and the data is recorded; 2, thermal resistance Rn and thermal capacity from the outer surface of the cable outer sheath to the soil temperature stable point are calculated through an iteration method according to the recorded data. The power grid dispatching under emergency loads of power grid dispatching personnel is provided, it can be avoided that the cable is damaged by loads exceeding the power grid dispatching, and unnecessary rush-repairing power outage can be avoided, which is beneficial for increasing the use ratio of the cable line.

Description

technical field [0001] The invention relates to a method for calculating the influence of the cable ampacity on the temperature of the inner conductor of the cable in a transient state, in particular to a calculation method for the emergency load ampacity of the power cable. Background technique [0002] When there is an accident on the transmission line, it is often necessary to switch the load on the original cable to other cables to maintain the normal power consumption of the user, but too much load will cause a large current and increase the burden on the cable. When the insulation of the cable exceeds a certain temperature, thermal breakdown will occur, so it is not feasible to carry out overload operation for a long time; because the grid dispatcher can generally distribute the load scheduling of the original cable before the accident to other parts of the grid within two hours. Therefore, it becomes particularly important to predict the temperature rise of temporaril...

AI Technical Summary

Problems solved by technology

[0002] When there is an accident on the transmission line, it is often necessary to switch the load on the original cable to other cables to maintain the normal power consumption of the user, but too much load will cause a large current and increase the burden on the cable. When the insulation of the cable exceeds a certain temperature, thermal breakdown will occur, so it is not feasible to carry out overload operation for a long time; because the grid dispatcher can generally distribute the load scheduling of the original cable before the accident to other parts of the grid within two hours. part, so it becomes particularly important to predict the temperature rise of temporarily overloaded cables within two hours under transient conditions

[0003] At present, the temperature rise of the inner conductor of the cable caused by the transient ampacity after two hours is mainly observed through specific experimental data, which lacks versatility and is relatively cumbersome in practical applications.

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