Influence of different arrangement types and number of power cables on the magnetic flux density

Abstract

The development of larger urban areas and the increase in electricity consumption in them require the use of cable lines with increasingly higher nominal voltages. In addition, these are regularly cable line systems that partly or entirely share common cable routes. Because such cable lines are one of the most significant sources of low-frequency magnetic fields, which have potentially harmful effects on human health, they are the subject of numerous studies. Numerical models for calculating magnetic flux density are based on the application of the Biot-Savart law, and in order to achieve the lowest possible values ​​of magnetic induction on the surface of the earth, various compensation methods are used. The limit levels of magnetic flux density are prescribed in the Ordinance on Protection against Electromagnetic Fields (Official Gazette 146/14). This paper describes a mathematical model for calculating the magnetic flux density of cable line systems, which can take into account an arbitrary number and arrangement of single-core cable systems arranged in a triangular bundle or laid in a plane at an arbitrary distance from each other. A matrix of reduction coefficients is used, which takes into account the complete electromagnetic coupling between the respective cable lines. The application of this model allows the calculation of the distribution of currents flowing through metal screens in the cable line system, and then the magnetic flux density at arbitrarily selected points, depending on the geometric arrangement and number of single-core cable systems, which is shown in the selected numerical example. In addition to the well-known factors that significantly affect the amount of magnetic flux density, such as current amounts and laying depth, the results obtained also indicate a significant influence of the laying method and arrangement of phase conductors, which can be used in the planning and design of new cable lines.

Tonći Modrić

Associate Professor | Department of Electrical Intallations and Systems

Researcher and Full Professor at the Faculty of Electrical Engineering, Mechanical Engineering, and Naval Architecture in Split. His research focus is numerical modeling and calculation of the electric and magnetic fields in power systems and transmission lines, with an emphasis on the development of advanced models for interpreting geoelectrical ground survey data. Additionally, he is involved in the analysis of electromagnetic transients in systems with a high share of renewable energy sources, using finite element techniques.