ALGORITHMS FOR SEARCHING FOR AN ACCEPTABLE OPERATING MODE OF A CABLE CHANNEL BASED ON AN ASSESSMENT OF ITS TEMPERATURE STATE

Abstract

The great majority of currently used cable products contain polymer materials in their construction, which tend to degrade their physical and electrical properties over time. This process is aggravated when the temperature of the product increases. The design of cable lines and the conditions of their collective laying, for example, in cable channels, complicate the thermal control of their operation, while the conditions of an isolated channel contribute to the heating of individual lines at the expense of neighboring ones. The existing engineering methods for calculating the cable temperature specified in IEC 60287-1-1-2009 do not allow taking into account all the features of a particular cable structure. Therefore, the task of a quick and accurate assessment of the thermal state of all polymer elements of the lines laid in the channel is very urgent. The paper considers the possibility of replacing direct observation of the thermal field of a cable channel with its equivalent mathematical model capable of determining stable stationary temperature distributions at given current loads of lines. Such a model, in addition to the speed of finding the desired parameters, has such an advantage over a real line as the ability to evaluate the internal temperature field of the cable without violating the integrity of its design. Using a mathematical model, it is proposed to analyze the thermal state of the channel by comparing the temperatures of the elements of cable lines with a predetermined setpoint. When the fact of exceeding the setpoint is detected, an algorithm is started for selecting such a combination of current loads at which the temperatures of the line elements do not exceed the set value. An additional criterion for selecting the mode is the minimum reduction of currents in comparison with their initial value. The algorithms proposed in this paper are universal and can be used for channels of various designs and with different numbers of lines, as well as for analyzing the operation of similar engineering structures, for example, ventilation ducts with transit lines of air conditioning systems, pipelines for hot liquids and gases. The developed algorithms are functionally suitable for creating specialized software operating in the mode of an adviser to the operator of an electricity distribution node. The software is designed to pre-evaluate any change in line loads, checking for possible overheating and giving the operator either approval of the mode, or offering a safe option for long-term operation.