Full
Outline
In a high-voltage flexible DC power transmission system, the modular multilevel converter (MMC) has unique advantages. Compared with those of the ordinary MMC, the output voltage levels of a hybrid-leg MMC (HL-MMC) consisting of submodules (SMs) and IGBT are doubled, the harmonic content of output voltage is reduced, and the DC bus voltage utilization is also doubled under the condition of the same number of SMs. The series-connected HL-MMC (SC-HL-MMC) is composed of three single-phase HL-MMCs, and its number of SMs is reduced by 2/3 under the condition of the same DC bus voltage. To be equipped with a DC short-circuit fault-tolerant capability, a hybrid SC-HL-MMC consisting of half bridge SMs (HBSMs) and full bridge SMs (FBSMs) is applied, and the scheme of optimal ratio between FBSMs and HBSMs is analyzed to satisfy the short-circuit fault ride-through requirement. To verify the performance of the proposed topology, a simulation model is built. Simulation results show that the stable three-phase output voltage from the SC-HL-MMC contains less harmonic under the rated operation condition, and it can block the short-circuit current rapidly under the DC short-circuit fault condition, thereby verify the validity of this topology.
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| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |
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