Fault-Tolerant Control of Medium-Voltage Modular Multilevel Converters With Minimum Performance Degradation Under Submodule Failures
Fault-Tolerant Control of Medium-Voltage Modular Multilevel Converters With Minimum Performance Degradation Under Submodule Failures
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DOI：
10.1109/access.2018.2811904
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发表时间：
2018
期刊：
影响因子：
3.9
通讯作者：
Binbin Li;Zigao Xu;Jian Ding;Dianguo Xu
中科院分区：
文献类型：
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作者：
Binbin Li;Zigao Xu;Jian Ding;Dianguo Xu
模块化多电平变换器（MMC）作为一种新型的电压源型变换器，在中、大功率场合具有广泛的应用前景。在MMC中，可靠性和不间断运行一直被视为首要关注点，这要求MMC即使在某些子模块（SM）发生故障时也能继续运行。本文提出了一种新的容错调制和控制策略的MMC在中压应用。与以前的作品相比，该策略提供了最佳的性能在健康的条件下和SM故障后的性能下降最小。在健康条件下，冗余SM被充分利用，以降低SM电容器电压以获得更高的可靠性，并降低开关频率以获得更高的效率。而在容错操作期间，通过适当修改调制和控制器，不需要旁路额外的健康SM，并且MMC的输出电压谐波保持不变，而不会引起电压失配。通过MATLAB/Simulink仿真和缩小的三相MMC样机实验验证了该控制策略的可行性和有效性。
As the state-of-the-art voltage-source topology, the modular multilevel converter (MMC) is attractive for various medium- or high-power applications. In MMC, reliability and uninterruptable operation are always seen as primary concerns, which requires the MMC can continue operating even though some of the submodules (SMs) are failed. In this paper, a novel fault-tolerant modulation and control strategy is proposed for MMC in medium voltage applications. Compared with previous works, the proposed strategy provides optimum performances under healthy conditions and minimum performance degradation after SM failures. During healthy conditions, the redundant SMs are fully utilized to decrease SM capacitor voltage for higher reliability and to reduce switching frequency for higher efficiency. While during fault-tolerant operation, by appropriate modification of the modulation and controllers, no extra healthy SMs need to be bypassed and the output voltage harmonics of MMC remain unchanged without causing voltage mismatches. Feasibility and effectiveness of the proposed strategy have been verified by simulations in MATLAB/Simulink software and experiments on a downscaled three-phase MMC prototype.