Parallel Virtual Impedance Based Fluctuation Power Delivery Strategy For MMC Based SST

2023 IEEE 14th International Symposium on Power Electronics for Distributed Generation Systems (PEDG) Pub Date : 2023-06-09 DOI:10.1109/PEDG56097.2023.10215131

Jaiyi Li, Jianqiao Zhou, Jianwen Zhang, G. Shi, Xu Cai, Y. Wang, Xiaofeng Dong, Wei Bao

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Abstract

Modular multilevel converter (MMC) based solid state transformer (MMC-SST) shows promise in hybrid AC/DC distribution grid. This paper introduces a topology consisting of cells made of directly coupled MMC sub-modules (SMs) and isolated SAB modules forming a multi-port SST for grid interconnection. Due to the large SM capacitors for low frequency fluctuation power handling, the device power density is low, which will limit its application. This paper proposes an MMC-SST SM capacitor optimization method based on fluctuation power delivery. It reduces the equivalent low frequency impedance of the SAB by parallel virtual impedance. Low frequency fluctuation power will be delivered into SAB circuit and naturally eliminated in low-voltage DC side due to three-phase symmetrical MMC-SST structure. Therefore, the SM capacitance could be optimized where the power fluctuation flowing into it are reduced. The feasibility of the proposed method is verified by a simulation model.

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基于并联虚阻抗的MMC型海温波动输电策略

基于模块化多电平变换器(MMC)的固态变压器(MMC- sst)在交直流混合配电网中具有广阔的应用前景。本文介绍了一种由直接耦合的MMC子模块(SMs)和隔离的SAB模块组成的多端口SST组成的拓扑结构，用于电网互连。由于用于低频波动功率处理的SM电容器体积较大，器件功率密度低，限制了其应用。提出了一种基于波动功率分配的MMC-SST同步电容优化方法。采用并联虚阻抗的方法，降低了等效低频阻抗。由于三相对称MMC-SST结构，低频波动功率将被送入SAB电路，在低压直流侧自然消除。因此，可以通过减小输入电容的功率波动来优化SM电容。仿真模型验证了该方法的可行性。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

2023 IEEE 14th International Symposium on Power Electronics for Distributed Generation Systems (PEDG)

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