基于零序电压注入的模块化多电平变流器故障容错控制

Fault-tolerant Control for Modular Multilevel Converter Based on Zero-sequence Voltage Injection

随着模块化多电平变流器(MMC)在高压大功率电能变换领域的应用日渐增多,其故障带来的损失将显著增加。为了解决上述问题,文中提出了一种针对三相三线制系统的MMC容错控制策略。利用电容电压冗余排序方法克服普通载波层叠脉宽调制方法所固有的功率不均衡;在详细阐述不同容错控制方案的基础上,提出零序电压注入方法,以保证线电压恒定为基本思路,对超出临界电压区间的调制波进行重构,使MMC具有可靠的故障穿越能力。最后,以一台4.5kVA的三相MMC样机为例进行了实验验证,实验结果验证了所述方案的正确性和可行性。

As mounting numbers of modular multilevel converters （MMCs） are increasingly applied in the field of high-voltage large-power energy conversion,the loss brought about by MMC failures will be significantly increased.To resolve this problem,a fault-tolerant control strategy for MMC in three-phase three-wire system configuration is proposed.The capacitor voltage redundant sorting method is adopted to overcome the inherent unbalanced power distribution of the phase disposition PWM.The zero-sequence voltage inj ection method is presented on the basis of elaboration of different fault-tolerant control schemes,to ensure the line voltage will remain constant.Then the modulation signals are reconfigured for the case in excess of the threshold voltage range,which enables the MMC system to possess a reliable fault ride-through capability.Finally,a three-phase 4.5 kVA MMC prototype is built for experimental validation.The experimental results have verified the correctness and feasibility of the scheme proposed.