基于CPOD与SMB-BiLSTM降阶的三维非线性瞬态磁场快速计算OA

Large-scale electrical equipment typically involves millions of nodes,leading to prohibitive computational costs in three-dimensional(3-D)nonlinear transient magnetic field simulations and making real-time simulation of elec-tromagnetic performance difficult to achieve.This paper proposes a fast calculation method for nonlinear transient magnetic fields based on cluster-enhanced proper orthogonal decomposition(CPOD)and stepwise multi-branch bidirec-tional long short-term memory(SMB-BiLSTM)reduced-order modeling.A reduced snapshot matrix is constructed via a multi-stage K-means spatial node reduction strategy to achieve efficient feature extraction of the magnetic fields in large-scale electrical equipment,and the dominant modes and their corresponding coefficient vectors are obtained.In ac-cordance with the 3-D transient characteristics,an SMB-BiLSTM network is established to calculate the temporal coefficient vectors under different excitation waveforms,thus the complex field solving problem is transformed into a prediction of the optimal linear combination of different modes,ultimately reconstructing the precise magnetic field dis-tribution.The efficiency of the proposed reduced-order model is verified by establishing fast calculation models for the TEAM Problem 24(a benchmark for nonlinear transient fields in rotating machines)and a 1 000 kVA amorphous alloy distribution transformer,and the results and computation time are compared with those of the full-order models.The re-sults demonstrate that the proposed method can be adopted to maintain high calculation accuracy(with average relative errors of 0.79％and 1.72％,respectively)and significantly improve the calculation efficiency of 3D nonlinear transient magnetic fields,achieving a speedup ratio of over 10 000 times.