一种基于桥臂电流畸变及自适应观测的MMC子模块开路故障诊断定位方法

Diagnosis and Location Method for Open-circuit Fault in MMC Sub-module Based on Bridge Arm Current Distortion and Adaptive Observation

模块化多电平换流器的子模块数量较多,增大了系统发生故障的概率,因此子模块故障的快速诊断和准确定位是保障换流器持续运行的关键。针对MMC子模块开路故障,提出了一种基于桥臂电流畸变及自适应观测的故障诊断和定位方法。通过对故障后桥臂电流的特征提取,判断出故障发生的桥臂以及开路故障的类型;然后利用自适应观测器得到子模块电容电压观测值与实际值的残差,从而实现故障子模块的快速和准确定位;最后利用Matlab/Simulink软件搭建MMC变换器仿真平台,通过对不同相、不同桥臂和不同类型的故障进行仿真,验证了所提故障诊断和定位算法的正确性与有效性。

A modular multilevel converter(MMC)consists of a large number of sub-modules,which increases the pro-bability of system fault.Therefore,the rapid diagnosis and accurate location of sub-module fault is the key to ensuring the continuous operation of the converter.Aimed at the open-circuit fault of MMC sub-modules,a fault diagnosis and location method based on bridge arm current distortion and adaptive observation is proposed.By extracting the characteristics of the bridge arm current after fault,the damaged bridge arm and the type of open-circuit fault are determined.Afterwards,the residual between the estimated and actual values of sub-module capacitor voltage is obtained by utilizing the adaptive observer,so that the faulty sub-module can be located rapidly and accurately.A simulation platform of MMC is built using software Matlab/Simulink,and the correctness and effectiveness of the proposed fault diagnosis and location method are verified by simulations of fault of different phases,different bridge arms,and different types.