Parallel‐in‐time‐and‐space electromagnetic transient simulation of multi‐terminal DC grids with device‐level switch modelling

Abstract

The electromagnetic transient (EMT) simulation of multi-terminal DC (MTDC) grids requires a detailed device-level modular multilevel converter (MMC) model, which can have thousands of state variables and complex internal structures. The fast device-level insulated gate bipolar transistor (IGBT) transient requires a very small time-step, making the computational overhead prohibitive. Based on the analysis of the parallel-in-time (PiT) implementation of detailed modelled MMCs, this paper proposes a task-based hybrid PiT algorithm to achieve high parallel efficiency and speed-up of MMC with device-level modelling. Moreover, a transmission line model(TLM)-based parallel-in-time-and-space (PiT+PiS) method is proposed to connect PiT grids to conventional or other PiT grids and exploit the maximum parallelism. Simulation results show greater than 30$\times$ speed-up and 60% parallel efficiency on a 48 cores computer for the hybrid PiT method in a 201-level three-phase MMC test case, and 20$\times$ speed-up in the transient simulation of CIGRÉ B4 DC grid test system for the PiT+PiS method.