Calculating for surface electric field of converter valve shield system with fast multipole curved boundary element method

The accurate and fast calculation of surface electric field of DC converter valve shield system have guiding significance in the designing process. However, the electrostatic field analysis is a large-scale problem with low efficiency using the conventional numerical algorithm. In order to solve this problem, fast multipole curved boundary element method (FMCBEM) was proposed. The FMCBEM is based on the indirect boundary integral equation of electrostatic field. Galerkin curved boundary element method based on coordinate transformation is used to improve the accuracy, then fast multipole method is used to improve the calculation speed and reduce the memory usage. Through simple examples, the accuracy and efficiency of the algorithm were verified. Compared with finite element method, it was found that the accuracy can meet the requirements of engineering. The efficiency was obviously better than the conventional boundary element method. Applying this algorithm, the surface electric fields of different shield systems of +/- 160kV converter valve, which the degree of freedoms is more than 220 thousand, were analysed using desktop computer. This algorithm can calculate the large-scale electric field problem fast and accurately, which is an effective tool for the optimisation design.