Research On Calculation Method For Analysis Of Power Frequency Electric Field Based On Boundary Element Method In Substaion

With the expansion of power grid scale and the development of UHV technology, increasing attention to electromagnetic pollution has been paid by people, and much stricter environmental standard of electric field has been commanded by the state. So analysis and governance of power frequency electric field (PFEF) in substations has been extremely important, substantial difficulties such as high computation and storage capacity, low computational efficiency and slow convergence speed has been caused by the existing boundary element method (BEM) for solving the problem. For the PFEF of technical difficulties in substations, the main research work of this dissertation is as follows①Calculation characteristics of PFEF in substation has been analyzed, the BEM integral equation based on Green function has been derived, the physics model for PFEF of substation has been simplified while the engineering reality is considered, the indirect boundary element mathematics model for electrode, suspend conductor and insulation dielectric is constructed, and the discrete model has been derived though surface six node element.②Coefficient matrix resulting from BEM for PFEF is densely populated, the generalized minimal residual(GMRES) algorithm combining the orthogonal Arnoldi method and the least square method is presented, higher convergence rate can be gotten by precondition which decompose the coefficient matrix by the way of incomplete LU or Cholesky. The model has been presented to demonstrate higher rate of convergence and less computational tine can be acquired than that of Gaussian seidel, conjugate gradient, quasi-minimal residual iteration.③Fast multipole BEM, which can improve the efficiency of matrix-vector multiplication while the PFEF in substation is solved by preconditioner GMRES algorithm, has been presented. This algorithm based on multipole expansion of Green function can accelerate the calculation of interaction between a large number of elements by the way of polymerization, transference and configuration. Implement steps can be given when oct-tree data structure is built according to the basic information of elements and bodes. Reliable accuracy and computation cost decreased substantially by this algorithm can be clearly demonstrated by electric field problem of dual dielectric and substation, so this algorithm is practical value for the solution of large-scale and multi-media PFEF problem.④The optimal fast mutipole BEM based on surface transformation for polymerization, transference and configuration has been presented, which is aimed to overcome the substantial acquirement of calculation time and storage when the accuracy is enhanced. Numerical results has found that the reliable accuracy and less computational cost can be achieved under the same accuracy, it is found that the optimal fast mutipole BEM is significantly better convergence rate than charge simulation method and boundary element charge simulation method, which are the currently used to analyze PFEF in substation.⑤The application software, which can establish model in an easier way, mesh automatically and display electric field distribution for regular activities and working area of staff in different way, has been developed for the analysis of PFEF in substation. It is useful for the following theoretical analysis and engineering application.