Temperature Analysis of Cable Lines Distributing Power under Changing Loads

Due to the constant growth in electricity consumption, increasing density of underground cable communications, and growing cost of cable products, the design and operations of cable lines are exhibiting a trend toward enhancing the efficiency of electricity distribution. Determination of the long-term permissible current of a cable line based on an analysis of cable temperature, taking into account the uneven loading of the entire unit, enables an increase is the transmitted power, thereby alleviating the need for the construction of new lines. The efficiency of cable lines under an emergency increase in electricity consumption can also be enhanced by using a partial reduction in load rather than the complete shutdown of lines. However, to determine the control actions for regulating the load regime, an analysis of a large number of combinations of operating currents and their corresponding temperature fields is required. To this end, a software package has been developed that makes it possible to calculate a large number of load options for cable lines and choose the optimal one. The developed program can be used for cable blocks with any number of lines. It does not require large computer resources and time, which is of importance when running the program in real time and maintaining existing cable structures. The optimal mode is selected from the condition of maintaining the operating temperature of the cable insulation within acceptable limits and the maximum possible value of the power transmitted over the lines.