In the field of cable system design and electromagnetic transient analysis

the rapid and accurate calculation of the wideband sequence impedance of three-core cables is of vital importance. However

the traditional calculation model generates errors due to the failure to consider the proximity effect. The electromagnetic transients program (EMTP) model focuses on single-frequency analysis

and the finite element model has poor calculation efficiency under wideband conditions. Therefore

in this paper

a fast calculation method of sequence impedance considering the proximity effect is established for three-core cables

and the current density of the conductor is decomposed by introducing the surface admittance operator. Meanwhile

the electric field integral equation is introduced to obtain the impedance of the conductor. The current density at multiple points and the impedance of the conductor are combined by using the method of moments

and the impedance matrix related only to the parameters of the conductor itself is obtained. This method can be called surface operator-enhanced electric field integral equation method of moments (SO-EI-MoM). On this basis

the unit impedances of two parallel conductors under wideband conditions are solved through the traditional analytical model

EMTP model

finite element model and SO-EI-MoM model

and their performances are compared to verify the significant advantages of the SO-EI-MoM model in terms of computational efficiency and accuracy. Furthermore

taking the YJV22-220 kV-3×500 mm² three-core cable as the empirical object

it is found that its computational efficiency is 88 times higher than that of the finite element method and 2 times higher than that of EMTP. At 50Hz

the average error between its calculation result and the actual value is 2.89%

which is better than the result of EMTP. Finally

based on this model

the variation law of the wideband sequence impedance of the three-core cable at different temperatures is analyzed and compared with the finite element simulation

further confirming its universality.