SCREEN SELECTION FOR THE POWER FREQUENCY MAGNETIC FIELD SHIELDING OF UNDERGROUND POWER CABLES.

Abstract

ABSTRACT: This paper introduces one of the most used techniques to mitigate the magnetic field generated by underground power cables, such as screen shielding. Due to the complexity of these systems, it is difficult to choose the type of screen to use in a particular situation and its dimensions. Therefore, numerical methods, such as the finite elements method, are required to solve the coupled electromagnetic-thermal problem. To show the recommended steps to follow in the selection and design process of a screen, the case of a 132 kV underground power line in flat formation is studied, where different open screens shapes made of aluminium are considered, taking into account the impact of the screen in the ampacity rating of the power line. In the selection process, an economic study is also developed as a function of the screen dimensions, considering the material cost and the cost related to the power losses induced in the screen. As a consequence, the type of screen and its dimensions are selected to meet the mitigation requirements in the final placement, the lower cost and the lower derating of the ampacity of the mitigated line.