Analysis of Hybrid Modular Multilevel Rectifier Operated at Nonunity Power Factor for HVDC Applications
Analysis of Hybrid Modular Multilevel Rectifier Operated at Nonunity Power Factor for HVDC Applications
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DOI：
10.1109/tpel.2022.3164099
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发表时间：
2022-09
影响因子：
6.7
通讯作者：
Jian Liu;Di Zhang;D. Dong
中科院分区：
文献类型：
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作者：
Jian Liu;Di Zhang;D. Dong
混合模块化多电平整流器（HMMR）是一种用于高压直流输电的单向模块化电压源换流器（VSC）。与模块化多电平换流器（MMC）相比，高达50%的子模块（SM）和电容器可以被单位功率因数（PF）的简单高压工频二极管堆取代。非统一PF操作也有利于整流站支持电网。为此，本文提出了两种新的电流换流方法，以减少在不统一的PF的SM数HMMR。此外，平均模型给出了揭示HMMR的内在功率流关系。研究发现，部分有功功率通过二极管直接从交流侧传递到直流侧，降低了储能要求。对HMMR的性能进行了评价，并与MMC进行了比较。这两种方法都可以成功地减少30%的低压器件。方法1可以减少32%的电容，方法2实现了52%的减少。从200 kV 200 MVA高压直流模型的仿真结果验证了所提出的转换器的可行性。最后，一个缩小的400-V的HMMR原型开发，以验证所提出的控制方案的有效性。
Hybrid modular multilevel rectifier (HMMR) is a type of unidirectional modular voltage source converter (VSC) that has been proposed for the high-voltage (HV) dc transmission applications. Compared to the modular multilevel converter (MMC), up to 50% of the submodules (SMs) and capacitors can be replaced by the simple HV line-frequency diode stacks at unity power factor (PF). The nonunity PF operation is also favored for the rectifier station to support the grid. Therefore, this article proposes two new current commutation methods for HMMR to reduce the SM number at nonunity PF. In addition, an average model is given to reveal the inherent power flow relationship of HMMR. It is found that part of the active power is delivered from ac to dc side through the diode directly, which reduces the energy storage requirement. The performance of HMMR is also evaluated and compared with MMC. Both methods can successfully decrease the 30% low voltage devices. Method 1 can reduce 32% capacitor and method 2 achieves 52% reduction. The feasibility of the proposed converter is verified by the simulation results from a 200-kV 200 MVA HVdc model. Finally, a scale-down 400-V HMMR prototype is developed to validate the effectiveness of the proposed control scheme.