Practical Solutions for Ground Grid Circulating Currents Caused by Air-Core Reactor

This study describes an actual problem with circulating current at the ground grid of an actual power system that has an air-core reactor. Such reactors generate a large amount of magnetic flux whose path can be closed through its underneath ground grid. This magnetic flux induces a voltage on the ground meshes and thus results in considerable circulating currents that pass through the ground meshes. Indeed, the main novelty of this study is investigating the effect of air-core reactors on the other nearby equipment and considering the air-core reactor's flux underneath ground meshes. This phenomenon occurred in a steel industrial plant and practically leads to severe damages to equipment through which the current has been flowing, including ground grid conductors, cable shields, and foundation armatures. This study addresses the origins of problems raised by the manufactured equipment in a reputable company based on both simulations and experimental studies. Based on the obtained results, several practical approaches are proposed and implemented to overcome the problems mentioned above.