电工技术学报  2023, Vol. 38 Issue (4): 1010-1022    DOI: 10.19595/j.cnki.1000-6753.tces.220423
电力电子 |
基于自适应滑模观测器的中点钳位型三电平并网逆变器开路故障诊断
许水清1, 黄文展1, 何怡刚1, 胡友强2, 程庭莉1
1.合肥工业大学电气与自动化工程学院 合肥 230009;
2.输配电装备及系统安全与新技术国家重点实验室(重庆大学) 重庆 400044
Open-Circuit Fault Diagnosis Method of Neutral Point Clamped Three-Level Grid-Connected Inverter Based on Adaptive Sliding Mode Observer
Xu Shuiqing1, Huang Wenzhan1, He Yigang1, Hu Youqiang2, Cheng Tingli1
1. College of Electrical Engineering and Automation Hefei University of Technology Hefei 230009 China;
2. State Key Laboratory of Power Transmission Equipment and System Security and New Technology Chongqing 400044 China
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摘要 为提高中点钳位型(NPC)三电平并网逆变器故障诊断的准确性和鲁棒性,该文针对其开关管单管和双管故障,提出一种基于自适应滑模观测器的开路故障诊断方法。该方法首先建立逆变器在正常状态和开关管故障状态下的混合逻辑动态模型;其次设计收敛速度快且显著抑制抖振的自适应滑模观测器精确估计正常状态下的三相电流值;然后利用实际系统和观测器的输出电流提出基于电流形态因子的故障检测方法;最后根据电流残差来构造故障定位变量进行故障定位。在此基础上,通过建立前次故障状态的自适应滑模观测器实现双开关管开路故障诊断。该文提出的方法能够同时实现单管和双管开路故障诊断,诊断速度快、鲁棒性强,且避免增加额外传感器。实验结果验证了该文所提诊断方法的鲁棒性和有效性。
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许水清
黄文展
何怡刚
胡友强
程庭莉
关键词 NPC三电平并网逆变器开路故障自适应滑模观测器电流形态因子    
Abstract:Neutral-point-clamped (NPC) three-level grid-connected inverter plays a pivotal role as an effective interface connecting new energy generation system and grid. However, the failure of any switch will cause the inverter to fail to work normally, resulting in significant economic losses and safety accidents. Some open-circuit fault diagnosis methods of NPC three-level inverters are proposed in recent years. However, these methods are heavily dependent on the quantity of the data, have a long diagnosis time, or only realize single switch fault diagnosis. This paper proposed a diagnosis method based on an adaptive sliding mode observer for single-switch and double-switches faults.
In this method, the mixed logic dynamic models of the inverter in the normal state and the open-circuit fault state were established at first, respectively. Then, an adaptive sliding mode observer with fast convergence and significant chattering suppression was designed to estimate the three-phase current in normal states. Subsequently, a fault detection method based on the current form factor was proposed using the output current of the actual system and the observer. Finally, the fault localization variable was constructed according to the current residual for fault localization. On this basis, the open-circuit fault diagnosis of double switches was realized by establishing an adaptive sliding mode observer of the previous fault state.
A hardware-in-loop experiment platform is built to verify the effectiveness and robustness of the proposed method. When the inverter works normally, the fault detection variable Ma is smaller than the adaptive threshold Ta, and the detection variable ηa=ηb=ηc. When Qa1 open-circuit fault occurs, the output currents are distorted to a certain extent, and the detection variable Ma exceeds the adaptive threshold Ta. Meanwhile, the detection variable ηa>ηb,ηc indicates that fault occurs in phase-a of the inverter. At the same time, the fault location variable Pa=3/2 can locate the open-circuit fault according to the fault diagnosis criteria. After the Qa1 fault is detected, replace the switch function δa1 in the Qa1 fault state with the original switch function δa, and the adaptive sliding mode observer under Qa1 fault state is constructed. Then the fault detection variable Ma is lower than the adaptive threshold Ta, which verifies the accuracy of the first fault diagnosis result. When an open-circuit fault occurs in Qa3, the fault detection variable Ma begins to exceed the adaptive threshold Ta, and the fault detection variable ηa also increases and is greater than ηb andηc. In contrast, the fault location variable meets Pa=-3/2, indicating that fault occurs in Qa3. It can be seen that the diagnosis method can realize the open-circuit fault diagnosis of double switches. In addition, after the grid voltage is increased from 220V to 305V, although the fault detection variables Ma, Mb and Mc all fluctuate to a certain extent, they are still far less than their corresponding adaptive thresholds and will not produce false alarms. Therefore, the robustness and reliability of the proposed diagnosis method are verified.
Through experimental verification and analysis, the proposed fault diagnosis method has the following advantages. (1) An adaptive sliding mode observer is established. An adaptive sliding mode observer with fast convergence speed and significant chattering suppression is constructed by designing a new adaptive reaching law. (2) A method for fault detection and localization is proposed. According to the designed current form factor, two fault detection feature quantities are constructed, and the adaptive threshold is designed. Meanwhile, the fault localization variable is constructed by combining the current residuals for fault localization, and the fault diagnosis results are more accurate and robust. (3) A double switches fault diagnosis method is proposed. After the first fault occurs, the adaptive sliding mode observer of the previous fault state is established by replacing the original switch function with the fault switch function, which verifies the accuracy of the first fault diagnosis and diagnoses the double switch open-circuit fault.
Key wordsNeutral-point-clamped (NPC) three-level grid-connected inverter    open-circuit fault    adaptive sliding mode observer    current form factor   
收稿日期: 2022-03-24     
PACS: TM464  
基金资助:国家重点研发计划项目(2016YFF0102200)、国家自然科学基金重点项目(51637004)、国家自然科学基金联合基金重点项目(U2034209)、国家自然科学基金面上项目(62273128)、国家自然科学基金青年项目(61803140)和中国博士后科学基金面上项目(2020M682474)资助
通讯作者: 胡友强 男,1977年生,博士,副教授,研究方向为新能源发电系统及其故障诊断。E-mail: yqhu@cqu.edu.cn   
作者简介: 许水清 男,1991年生,博士,副教授,研究方向为电气设备的在线监测与故障诊断。E-mail: xsqanhui91@gmail.com
引用本文:   
许水清, 黄文展, 何怡刚, 胡友强, 程庭莉. 基于自适应滑模观测器的中点钳位型三电平并网逆变器开路故障诊断[J]. 电工技术学报, 2023, 38(4): 1010-1022. Xu Shuiqing, Huang Wenzhan, He Yigang, Hu Youqiang, Cheng Tingli. Open-Circuit Fault Diagnosis Method of Neutral Point Clamped Three-Level Grid-Connected Inverter Based on Adaptive Sliding Mode Observer. Transactions of China Electrotechnical Society, 2023, 38(4): 1010-1022.
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https://dgjsxb.ces-transaction.com/CN/10.19595/j.cnki.1000-6753.tces.220423          https://dgjsxb.ces-transaction.com/CN/Y2023/V38/I4/1010