基于子模块电压分组检测的MMC子模块开路故障诊断定位方法

模块化多电平变流器(MMC)子模块数目较多时，系统结构复杂且发生故障概率较高。针对子模块的开路故障诊断问题，提出一种基于子模块电压分组检测的MMC子模块开路故障诊断定位方法。分析子模块故障特性，通过对比子模块组输出电压的预测值和实际值获得检测判据，根据检测判据诊断故障发生的子模块组及故障类型；改变子模块的工作状态，根据检测判据进行故障定位；定量分析分组检测时子模块电容电压的测量误差，为子模块电压分组提供依据。通过MATLAB/Simulink搭建49电平MMC仿真平台，在电容值偏移的情况下对不同类型的故障进行仿真，仿真结果表明，所提故障诊断定位方法能在减少电压传感器数量的情况下实现子模块开路故障诊断定位，提升系统的可靠性。

Sub-module open fault diagnosis and location method of MMC based on sub-module voltage packet detection

With a large number of sub-modules of MMC(Modular Multilevel Converter),the system structure is complicated and the probability of failure is high. Aiming at the problem of sub-module open fault diagnosis, a sub-module open fault diagnosis and location method of MMC based on sub-module voltage packet detection is proposed. The fault characteristics of sub-modules are analyzed, the detection criterion is obtained by comparing the predicted value and actual value of the output voltage of the sub-module group, and the sub-module group and fault type are diagnosed according to the detection criterion. The working state of the sub-module is changed, and the fault is located according to the detection criterion. The measurement error of the sub-module capacitor voltage is analyzed quantitatively during the packet detection to provide a basis for sub-module voltage packet detection. A 49-level MMC simulation platform is built with MATLAB/Simulink, and different types of faults are simulated under the condition of capacitance value deviation. The simulative results show that the proposed fault diagnosis and location method can realize the sub-module open fault diagnosis and location when reducing the number of voltage sensor, so as to improve the system reliability.