Hybrid Cascaded Modular Multilevel Converter With DC Fault Ride-Through Capability for the HVDC Transmission System
Hybrid Cascaded Modular Multilevel Converter With DC Fault Ride-Through Capability for the HVDC Transmission System
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DOI：
10.1109/tpwrd.2015.2389758
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发表时间：
2015-01
影响因子：
4.4
通讯作者：
Rui Li;G. Adam;D. Holliday;J. Fletcher;B. Williams
中科院分区：
文献类型：
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作者：
Rui Li;G. Adam;D. Holliday;J. Fletcher;B. Williams
提出了一种用于高压直流输电系统的新型混合级联模块化多电平变流器。半桥单元用于主功率级，级联全桥（FB）单元连接到其交流端子。主功率级以相当低的开关频率产生基波电压，从而导致相对低的损耗。级联的FB单元仅衰减主功率级产生的谐波，而不会对功率传输做出贡献。因此，级联的FB单元的能量存储要求低，并且FB单元的电容显著减小。由于级联FB单元的直流故障反向阻断能力，该拓扑结构可以穿越极间直流故障。此外，在故障消除后实现软重启，而不会使系统暴露于显著的浪涌电流。此外，该拓扑的平均值模型的推导，在此基础上提出的控制策略。结果表明，所提出的转换器的可行性。
A new hybrid cascaded modular multilevel converter for the high-voltage dc transmission system is presented. The half-bridge cells are used on the main power stage and the cascade full-bridge (FB) cells are connected to its ac terminals. The main power stage generates the fundamental voltages with quite low switching frequency, resulting in relatively low losses. The cascaded FB cells only attenuate the harmonics generated by the main power stage, without contribution to the power transfer. Thus, the energy-storage requirement of the cascaded FB cells is low and the capacitance of FB cells is reduced significantly. Due to the dc fault reverse blocking capability of the cascaded FB cells, the proposed topology can ride-through the pole-to-pole dc fault. In addition, the soft restart is achieved after the fault is eliminated, without exposing the system to significant inrush current. Besides, the average-value model of the proposed topology is derived, based on which the control strategy is presented. The results show the feasibility of the proposed converter.