A Numerically Efficient and Accurate Model for Real-Time Simulation of Solid-State Transformer Using Implicit-Explicit Integration Methods

Electromagnetic transient (EMT) models of power electronic converters are essential for converter design, control, and fault analysis. This paper proposes a switching-function-based detailed equivalent model (SFB-DEM) using combined implicit and explicit (ImEx) multi-step Gear's integration methods for numerically efficient and accurate EMT simulation. The proposed SFB-DEM integrates the benefits of implicit and explicit solvers, featuring converter circuit decoupling, node number reduction, and constant nodal-network conductance(G)-matrix in the EMT model. The SFB-DEMs employing the ImEx 2ndand 3rdorder Gear's (i.e., ImEx-G2O and ImEx-G3O) methods are implemented for solid-state transformer (SST) simulation. Additionally, a switching interpolation technique is proposed and integrated with the ImEx-G2O and ImEx-G3O solvers to account for intra-time-step switching events. The proposed SST SFB-DEMs greatly accelerate the EMT simulation, compared to the conventional detailed model (DM) and variable conductance(G)-matrix DEM (VG-DEM). For the SST with 60 SMs, the proposed SFB-DEM with ImEx-G3O method achieves the EMT simulation speedup by 171 and 7.5 folds, compared to the DM and VG-DEM, respectively.