In many instances

the analysis of equipment electromagnetic environment in the power system can be regarded as electrostatic field analysis

encompassing converter valves

transformers

transmission lines

and other components. As a numerical analysis tool

the boundary element method(BEM) can effectively calculate electrostatic field problems due to the advantages of reduced problem dimensions

high adaptability to open domain problems

high computational accuracy

etc. Notably

when combined with the fast multipole method(FMM) and the curved boundary element method(CBEM) based on coordinate transformation

the fast multipole curved boundary element method(FMCBEM) can quickly and accurately analyze large-scale practical engineering problems. To address the issue of needing to provide surface model feature parameters before computation in CBEM

and to minimize the preparatory work

we extract the surface model parameters using surface fitting. This approach enhances the convenience and efficiency of fast multipole curved boundary element method(FMCBEM) when dealing with large-scale problems. The method employs the normal vectors and curvatures of partial nodes to determine typical surface types and use the least square method to fit regular surfaces. The accuracy of fitting parameters by using different models is verified

thereby ensuring the practicality of using fitting parameters for FMBEM in large-scale problems.