The emerging voltage source converters (VSCs) such as hybrid cascaded multilevel converters (HCMCs) are promising converter technologies which enable higher converter efficiency, compactness, and DC fault resilience for high voltage direct current (HVDC) transmission. However, the large number of switching events due to the converters' submodules introduces a heavy computational burden for electromagnetic transient (EMT) simulations. Efficient and accurate EMT-type converter models play a vital role in the control and design of HVDC converters. Several computationally efficient models for the HCMCs are proposed in this paper, including the detailed equivalent model (DEM) and several average value models (AVMs) of varying accuracy. Additionally, a combined model is proposed which allows the users to switch among the DEM and AVMs during dynamic simulations. The proposed models are validated against the DEM for dynamic transients. The simulation results demonstrate good modeling accuracy of the proposed models. The AVMs are also shown to significantly improve simulation efficiency compared to the DEM, which is very desirable especially for HCMCs with a large number of submodules.

中文翻译：

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用于高效、准确 EMT 型仿真的混合级联多电平转换器的详细等效模型和平均值模型


混合级联多电平变流器 (HCMC) 等新兴电压源变流器 (VSC) 是很有前途的变流器技术，可为高压直流 (HVDC) 传输提供更高的变流器效率、紧凑性和直流故障恢复能力。然而，转换器子模块导致的大量开关事件给电磁瞬态 (EMT) 仿真带来了沉重的计算负担。高效、准确的EMT型换流器模型在HVDC换流器的控制和设计中发挥着至关重要的作用。本文提出了 HCMC 的几种计算有效的模型，包括详细的等效模型（DEM）和几种不同精度的平均值模型（AVM）。此外，还提出了一种组合模型，允许用户在动态仿真期间在 DEM 和 AVM 之间切换。所提出的模型针对动态瞬态 DEM 进行了验证。仿真结果表明所提出的模型具有良好的建模精度。与 DEM 相比，AVM 还被证明可以显着提高模拟效率，这对于具有大量子模块的 HCMC 来说是非常理想的。