Development of thermal equivalent circuits for calculating the temperature transients of underground HVCL with XLPE insulation

The authors present a study that validates the typology and methods for calculating parameters of a thermal equivalent circuit and describing temperature transients in the cross section of a three-phase high voltage cable line. The method of calculating circuit parameters was examined as a principal methods of cable laying, namely, in trefoil and flat core formations. The resulting circuit takes into account cables' thermal mutual effect and explicit heat release in screens. The proposed circuit will facilitate prediction of cable heating in real time to prevent thermal breakdown of insulation. To this end, we have demonstrated the necessity of considering total earth impact on thermal transients, as forecasting requires knowledge of initial conditions.