Modeling Cable Lines Heating by Currents of Higher Harmonics and Interharmonics

The article discusses the issues of cable lines reliable operation provision. The main factors of the decrease in electric strength affecting the insulating materials used in high and low voltage cables are indicated. The heating temperature of the insulation is distinguished from a set of influencing factors because, when the permissible values are exceeded, various chemical reactions occurring between the insulation materials, internal inclusions, the environment and absorbed moisture are accelerated. The causes of the currents and voltages occurrence with the frequencies other than the main frequency in electric networks are shown. The experimental results of the electrical energy quality measurements confirming the existence of the currents and voltages of both higher harmonics and interharmonics in the power supply systems are given. A model for determining the power losses in the current-carrying conductors of cables, under the action of which the insulation is heated is proposed. This model allows one to take into account heating of the insulation by the currents of the main frequency, higher harmonics and interharmonics.