MMC子模块单管开路故障的新型诊断方法研究

A New Method for Fault Diagnosis of Single-tube Open-circuit Fault in Modular Multilevel Converter

针对模块化多电平换流器(MMC)的子模块单管开路故障,分析了开路故障后的现象,提出一种新型的故障诊断方法。首先,说明了执行基于排序法的电容电压平衡算法(CVBS)对故障子模块电容电压上升的抑制作用。并阐述当执行CVBS时,根据电容电压是否超过阈值进行故障诊断的这一诊断机制可能失效的原因。接下来,提出了一种对于执行CVBS依旧有效的故障诊断方法。最后,搭建了8模块的单相MMC平台,实验结果验证了CVBS对子模块电容电压的影响和所提故障诊断方法的正确性和有效性。

Aiming at the single-tube open-circuit fault of the modular multilevel converter（MMC）, the phenomenon of open-circuit fault is analyzed, and a new fault diagnosis method is proposed.Firstly, it explains that the implementation of capacitor voltage balance algorithm based on the sorting method （CVBS） on the fault sub-modules＇ capacitor volt- age rise suppression.Then, it explains why this diagnostic mechanism may fail due to whether the capacitor voltage exceeds the threshold when performing CVBS.Next, a fault diagnosis method for performing CVBS is proposed.Finally, the 8-module single-phase MMC platform is built.The experimental results verify the effect of CVBS on the capaci- tance voltage of the sub-module and the correctness and validity of the proposed fault diagnosis method.