Harmonic-based 3D thermal analysis of thyristor-controlled reactor's power cable joints considering external electromagnetic fields

•3D thermal analysis of TCR's power cables joints considering the current harmonics.•FEM-based accurate thermal analysis of power cable joints.•Considering the external electromagnetic field of air-core reactors on thermal behaviors.•Studying the sheath bonding method impacts on thermal behaviors.•Investigating the free and forced convection method on thermal behaviors. The power cable system of thyristor-controlled reactors (TCRs), particularly their terminations and joints, experience severe electro-thermal conditions because of current harmonics and external electromagnetic fields due to air-core reactors. Although several research works have been introduced for thermal analysis of power cable systems, there is a research gap in thermal analysis of special industrial cable systems, like the TCR's cables. This paper tries to fill such a research gap by proposing the harmonic-based 3D thermal analysis of TCR's cable joints considering the impacts of external electromagnetic fields. The superposition of thermal effects of current harmonics and external electromagnetic fields besides implementation defectiveness, such as imperfect connections, could make an extreme thermal condition, which is studied in this article. The evaluation of sheath bonding impacts on the thermal behavior of TCR's cable joint is another contribution. The proposed study is applied to an actual test system that previously experienced a fault in TCR cable joints by the COMSOL Multiphysics. The simulation results emphasize the effects of current harmonics on the thermal behaviors of the TCR's cable joints. Moreover, test results show that the implementation defectivenesses besides current harmonics and external electromagnetic fields could raise the joint temperature up to 100 °C.