The efficiency of multiterminal dc (MTDC) grid simulation decreases with an expansion of its scale and the inclusion of accurate component models. Thus, the variable time-stepping scheme is proposed in this paper to expedite the electromagnetic transient computation. A number of criteria are proposed to evaluate the time-step and regulate it dynamically during simulation. Meanwhile, as the accuracy of results is heavily reliant on the switch model in the modular multilevel converter, the nonlinear behavioral model with a greater accuracy is proposed in addition to the classic ideal model, and their corresponding variable time-stepping schemes are analyzed. Circuit partitioning is effective in accelerating the MTDC grid simulation via fine-grained separation of nonlinearities. A subsequent large number of identical circuits enabled a massively parallel implementation on the graphics processing unit, which achieved a remarkable speedup over the CPU-based implementation. The inclusion of variable time-stepping schemes eventually makes the simulation of MTDC grid with highly detailed nonlinear switch models feasible. The results are validated by commercial device-level and system-level simulation tools.

中文翻译：

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多端直流电网快速并行瞬态仿真的可变时间步进模块化多电平转换器模型

多端直流 (MTDC) 电网仿真的效率会随着其规模的扩大和包含准确的组件模型而降低。因此，本文提出了可变时间步长方案以加快电磁暂态计算。提出了许多标准来评估时间步长并在模拟过程中对其进行动态调节。同时，由于模块化多电平转换器中结果的准确性严重依赖于开关模型，因此除了经典的理想模型外，还提出了精度更高的非线性行为模型，并对其相应的可变时间步长方案进行了分析。电路分区通过非线性的细粒度分离在加速 MTDC 电网仿真方面是有效的。随后大量相同的电路实现了在图形处理单元上的大规模并行实现，这比基于 CPU 的实现实现了显着的加速。包含可变时间步长方案最终使具有高度详细非线性开关模型的 MTDC 电网仿真变得可行。结果由商业设备级和系统级仿真工具验证。