基于SMA-VMD和优化神经网络的逆变器开关故障诊断  

Fault diagnosis based on SMA-VMD and optimization of neural networks for NPC three-level inverters

作　　者：李冉 邢砾云 庞娜 沈建强 王策 Li Ran;Xing Liyun;Pang Na;Shen Jianqiang;Wang Ce(College of Electrical and Information Engineering,Beihua University,Jilin 132021,China;State Grid Liaoyuan Power Supply Company,Liaoyuan 136200,China)

机构地区：[1]北华大学电气与信息工程学院,吉林132021 [2]国网辽源供电公司,辽源136200

出　　处：《电子测量技术》2024年第10期1-9,共9页Electronic Measurement Technology

基　　金：吉林省科技发展计划项目(YDZJ202201ZYTS601);吉林省教育科学“十四五”规划2022年度重点课题(ZD22091);国家自然科学基金(42004153);北华大学青年科技创新团队项目(202016003)资助。

摘　　要：为解决基于电流的中点箝位式三电平逆变器开路故障诊断易受负载变化影响的问题,本文从提升故障特征区分度入手,首先,基于SMA优化VMD的最佳模态数K及惩罚系数α,改善模态混叠现象,提高了故障特征的独立性。其次,基于小波包能量分布相对平稳,能有效克服负载影响的特点,将各IMF的两层小波包能量最大值作为故障特征量,在克服负载影响的同时,使时频特征信息更集中,进一步提高了故障特征区分度。最后,将上述故障特征应用于神经网络进行训练,并引入SSA对模型的权值和阈值进行优化,解决了模型局部最优问题,提升了故障辨识的准确性。通过NPC三电平逆变电路模拟17种开路故障的仿真实验,结果表明,该方法的诊断准确率达到98.99%,适用于变负载工况下NPC三电平逆变器在线故障诊断。In order to solve the problem that the current-based midpoint-clamped three-level inverter open-circuit fault diagnosis is easily affected by the load changes,this paper mainly improves the accuracy from the fault feature differentiation.Firstly,VMD improves the modal aliasing phenomenon,and its optimal modal number K and penalty coefficientαare optimized by SMA,which improves the independence of fault features.Second,due to the relatively smooth distribution of wavelet packet energy,which can effectively overcome the characteristics of load influence,the maximum value of the two-layer wavelet packet energy of each IMF is taken as the fault feature quantity,so that the time-frequency feature information is more centralized which further improves the fault feature differentiation without the influence of varying loads.Finally,the fault features are applied to the neural network for training,and the weights and thresholds of the model are optimized by SSA,which solves the problem of local optimum of the model and improves the accuracy of fault identification.Through the simulation experimental results of 17 open-circuit faults in the NPC three-level inverter circuit model,the diagnostic accuracy of this method reaches 98.99%,which is applicable to the online fault diagnosis of NPC three-level inverters under variable load conditions.

关 键 词：NPC三电平逆变器 开路故障诊断 VMD 小波包能量 神经网络 

分 类 号：TN306[电子电信—物理电子学]