Background. Currently, mathematical models of power cable lines rated at 110 kV and higher, implemented in various software packages, are based on symmetrical component and phase coordinate methods. These models are not suitable to represent the equivalent circuit of a cable line when considering insulation breakdown between the current-carrying conductor and the shield. It is the most probable type of fault in cable lines within electric power systems with solidly or effectively grounded neutrals. The key limitations of such models include the inability to simulate intermediate grounding of the shield and the simplified representation of the magnetic field generated by the fault current in the damaged section of the shield. Thus, the task of mathematically modeling cable lines rated at 110 kV and higher under single-phase insulation faults between the conductor and the shield is relevant.
Materials and methods. The study employs methods of electrical circuit mathematical modeling, matrix-based solutions of systems of linear algebraic equations, and the calculation of self and mutual inductance coefficients based on the magnetic vector potential.
Results. A mathematical model of a 110 kV power cable line has been developed to simulate insulation breakdown between the conductor and the shield. In contrast to existing models, the developed model allows for intermediate grounding of the shield and represents the shield as a volumetric conductor. The model has been validated using the PSCAD and MathCAD software environments.
Conclusions. The developed mathematical model can be used to design an equivalent circuit of a 110 kV or higher voltage cable line to simulate insulation breakdown between the conductor and the shield.