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253 results on '"Cai, Guowei"'

1. Fault Diagnosis for Power Electronics Converters based on Deep Feedforward Network and Wavelet Compression

Author

Kou, Lei, Liu, Chuang, Cai, Guowei, and Zhang, Zhe

Subjects
Electrical Engineering and Systems Science - Signal Processing, Computer Science - Machine Learning, 68T07, I.2
Abstract

A fault diagnosis method for power electronics converters based on deep feedforward network and wavelet compression is proposed in this paper. The transient historical data after wavelet compression are used to realize the training of fault diagnosis classifier. Firstly, the correlation analysis of the voltage or current data running in various fault states is performed to remove the redundant features and the sampling point. Secondly, the wavelet transform is used to remove the redundant data of the features, and then the training sample data is greatly compressed. The deep feedforward network is trained by the low frequency component of the features, while the training speed is greatly accelerated. The average accuracy of fault diagnosis classifier can reach over 97%. Finally, the fault diagnosis classifier is tested, and final diagnosis result is determined by multiple-groups transient data, by which the reliability of diagnosis results is improved. The experimental result proves that the classifier has strong generalization ability and can accurately locate the open-circuit faults in IGBTs., Comment: Electric Power Systems Research

Published
2022
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2. Review for AI-based Open-Circuit Faults Diagnosis Methods in Power Electronics Converters

Author

Liu, Chuang, Kou, Lei, Cai, Guowei, Zhao, Zihan, and Zhang, Zhe

Subjects
Electrical Engineering and Systems Science - Systems and Control, Computer Science - Artificial Intelligence, 68T99, I.2
Abstract

Power electronics converters have been widely used in aerospace system, DC transmission, distributed energy, smart grid and so forth, and the reliability of power electronics converters has been a hotspot in academia and industry. It is of great significance to carry out power electronics converters open-circuit faults monitoring and intelligent fault diagnosis to avoid secondary faults, reduce time and cost of operation and maintenance, and improve the reliability of power electronics system. Firstly, the faults features of power electronic converters are analyzed and summarized. Secondly, some AI-based fault diagnosis methods and application examples in power electronics converters are reviewed, and a fault diagnosis method based on the combination of random forests and transient fault features is proposed for three-phase power electronics converters. Finally, the future research challenges and directions of AI-based fault diagnosis methods are pointed out., Comment: Power System Technology

Published
2022
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9. A Three Phase Voltage Restorer Based on Bipolar Direct AC/AC Converters

Author

Wang Yibo, Zhang Xinyi, Liu Chuang, Cai Guowei, Liu Yu, Liu Kaipu, and Wang Yuan

Subjects
Distribution network, voltage sag/swell, voltage restorer, bipolar direct AC/AC converter, amplitude, phase angle control, Electrical engineering. Electronics. Nuclear engineering, TK1-9971
Abstract

A new topology is proposed to regulate voltage sags/swells in the distribution network in this paper. Voltage sags and swells are a serious power quality problem faced by the power industry. Based on energy storage devices, the major traditional voltage restorer is not adequate for compensating deep and long-duration voltage sags/swells. To solve this problem, a novel bipolar direct AC/AC type voltage restorer (AC/AC-VR) topology is proposed, with bipolar regulation ability and no storage device. The restorer of each phase is connected to the other two phases and the power is tapped from them. By controlling the duty cycle of each AC/AC converter, the required voltage is realized to maintain stability. Analysis, simulation, and experimental results are presented to demonstrate the proposed topology.

Published
2023
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11. Research on the deep peak-shaving cost allocation mechanism considering the responsibility of the load side

Author

Zhao Yang, Wang Yibo, Liu Chuang, Cai Guowei, Ge Weichun, Xu Yueyang, and Xiang Ziwei

Subjects
deep peak-shaving, value assessment, benefit distribution, load side, market rules, General Works
Abstract

With the goal of carbon reduction, China has carried out a series of institutional reforms and innovations in renewable energy consumption. However, the existing allocation rules for peak-shaving costs concentrate on the power side only. In the context of high energy penetration rates, peak-shaving cost significantly increases, and the economic pressure on the power side sharply increases. As the beneficiaries of peak shaving, the load side, while enjoying clean energy, also needs to bear the responsibility of peak shaving and share part of the peak-shaving cost. In this regard, this paper proposes a peak-shaving cost allocation mechanism considering load-side participation. First, it uses the marginal contribution theory to establish the peak-shaving value evaluation model of the power and load. Then, based on the waveform similarity theory, it sets two indicators “Fluctuation Trend Similarity” and “Waveform Amplitude Difference” to evaluate each load’s renewable energy consumption responsibility. Finally, the peak-shaving cost allocation rules on the power source side and the load side are obtained. An example shows that the proposed allocation mechanism can initially realize the uniform distribution of power and load in peak-shaving cost. Furthermore, the method can promote the fairness of the peak-shaving market and guide users to reasonably participate in the peak-shaving market.

Published
2023
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20. Novel Bidirectional High-Frequency Isolated Direct AC/AC Converter With Unipolar Phase-Shifted Modulation Strategy

Author

Guo, Dongbo, Wang, Aoran, Liu, Chuang, Zhang, Pinjia, Yan, Guanyu, Pei, Zhongchen, Cai, Guowei, Wang, Rutian, and Wang, Yibo

Abstract

This article introduces a novel bidirectional high-frequency isolated direct ac/ac converter with unipolar phase-shifted modulation strategy based on double dc modulation indexes. The main idea of topological construction is that the non-isolated two-level nondifferential bipolar direct ac/ac converter is combined to the bidirectional phase-shifted full-bridge converter, which inherits the advantages of no commutation problem, zero voltage switching, simple control, bipolar output voltage gains, et al. The operating principles of this converter and the design considerations for the key parameters are given in detail. Moreover, the application in voltage sag/swell compensation is simply analyzed. Thanks to the high-frequency isolation capability, it satisfies needs of distribution networks in terms of sensitive loads protection, voltage resilience control without applying the bulky line frequency transformers. Finally, the feasibility of this proposed topology is verified by the various experimental results of the prototype.

Published
2024
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23. Power‐frequency oscillation suppression algorithm for AC microgrid with multiple virtual synchronous generators based on fuzzy inference system

Author

Zhang, Liang, Zheng, Hao, Cai, Guowei, Zhang, Zhe, Wang, Xuesong, Koh, Leong Hai, School of Electrical and Electronic Engineering, and Energy Research Institute @ NTU (ERI@N)

Subjects
Frequency Oscillations, Renewable Energy, Sustainability and the Environment, Electrical and electronic engineering [Engineering], Fuzzy Inference Systems
Abstract

In the microgrid, virtual synchronous generator technology can significantly enhance the anti-interference characteristics of the system frequency and bus voltage, as well as solve the problems of insufficient damping and low inertia. However, the system frequency and active power oscillation caused by power fluctuations and grid faults threaten the stable operation of the grid seriously. Therefore, for an alternating current (AC) microgrid multi-virtual synchronous generator (VSG) parallel system, an improved virtual synchronous generator control algorithm based on a fuzzy inference system is proposed, which adjusts the values of virtual inertia and damping coefficient dynamically through fuzzy logic rules to realize the coordinated control of the two. The enhanced VSG algorithm described in this research has a substantial influence on power-frequency oscillation suppression, decreases active power and frequency overshoot, shortens the adjustment time, and improves system frequency stability active power, according to simulation and experimental findings. Published version This research was supported in part by the International Science and Technology Cooperation Project of Jilin Province Science and Technology Department, grant number 20210402080GH, the author hereby expresses his gratitude to the abovementioned institution for their support.

Published
2022

24. Mechanism Enhanced Data-Driven Method for Reliability Improvement of Load Margin Estimation

Author

Gao, Han, Wang, Lixin, Yang, Deyou, and Cai, Guowei

Abstract

The data-driven method for security monitoring is promising for power system voltage stability estimation, whereas the reliability of such method is greatly affected due to the generalizability weakened by operational variability. In this article, a mechanism knowledge enhanced machine learning method for load margin estimation is established by integrating power system mechanism into intelligent neural network (NN) model. Firstly, the correlation between the load power factor and load margin explored from curve P-V were analyzed, from which the mechanism knowledge of voltage stability is extracted. Then, the mathematical logical representation of mechanism knowledge is given, which was further integrated into the loss function of the NN model. The proposed enhanced model constrains the NN model to provide mechanistically consistent results, as well as helps achieve an excellent generalizability performance. The effectiveness of the proposed method is verified by numerical simulations using the IEEE 39-bus test system and the IEEE 145-bus test system, the results of which shows that the generalization ability of the enhanced NN is significantly improved with the proposed method, thus the accuracy, reliability and robustness of the load margin estimation are greatly enhanced.

Published
2024
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25. Sparse Measurement-Based Modelling Low-Order Dynamics for Primary Frequency Regulation

Author

Wang, Bo, Zhu, Shishuai, Cai, Guowei, Yang, Deyou, Chen, Zhe, Ma, Jin, and Sun, Zhenglong

Abstract

Developing a low-order model for a target with dynamic analysis and control of the primary frequency regulation (PFR) is critical for power system stability. Measurement-based modelling is an important way to improve the model fit with practical systems. The traditional interpretation of PFR is based on the combined effect of each generator unit on the system frequency, so the response of each unit needs to be measured for modelling. With the integration of a large number, distribution and diversified frequency regulation of units into a power system, it will be a burden to measure the response of all generation units. Instead of revealing the PFR dynamics based on each generation unit, this paper illustrates the impact of all units on the frequency dynamics from the perspective of the system response. Only the system frequency is needed to construct a dataset for identifying the PFR model so that the measurement required is sparse. The effectiveness of the proposed method is verified using a test system containing multiple types of units in numerical simulations and real measurements of an actual power system.

Published
2024
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26. Ambient Data-Driven Online Tracking of Electromechanical Modes Using Recursive Subspace Dynamic Mode Decomposition

Author

Zhou, Shuyu, Yang, Deyou Y., Cai, Guowei, Wang, Lixin, Chen, Zhe, Ma, Jin, and Wang, Bo

Abstract

The extraction of electromechanical modal parameters from ambient data is a useful and practical method that can monitor the modal properties of power system oscillations online. This paper proposes a recursive subspace dynamic mode decomposition (RSub-DMD) algorithm for online monitoring power system modes using wide-area synchronized ambient data. By introducing Givens rotation to the recursion process, the computational capability of subspace dynamic mode decomposition has been significantly improved without compromising accuracy. The shorter sliding data window enables the proposed RSub-DMD to quickly track the electromechanical modal parameters and participation factors (PFs), with low estimation variance. IEEE 16 generator 68 bus test system and measurement data from real system are used to verify the performance of the proposed RSub-DMD algorithm. The tracking results in different operating environments verify the effectiveness of the proposed algorithm.

Published
2023
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39. Imaging Study on Acupuncture Inhibiting Inflammation and Bone Destruction in Knee Osteoarthritis Induced by Monosodium Iodoacetate in Rat Model

Author

Tan,Qian, Cai,Zhengkun, Li,Jia, Li,Jing, Xiang,Hongchun, Li,Bocun, Cai,Guowei, Tan,Qian, Cai,Zhengkun, Li,Jia, Li,Jing, Xiang,Hongchun, Li,Bocun, and Cai,Guowei

Abstract

Qian Tan,1,* Zhengkun Cai,2,* Jia Li,3 Jing Li,1 Hongchun Xiang,1 Bocun Li,1 Guowei Cai1 1Department of Acupuncture, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, People’s Republic of China; 2Department of Public Administration, Huazhong University of Science and Technology, Wuhan, People’s Republic of China; 3College of Acupuncture and Orthopedics, Hubei University of Chinese Medicine, Wuhan, People’s Republic of China*These authors contributed equally to this workCorrespondence: Guowei CaiDepartment of Acupuncture, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, People’s Republic of ChinaEmail cgw645@163.comObjective: We aim to explore whether acupuncture inhibits inflammation and bone destruction in rat model monosodium iodoacetate (MIA)-induced knee osteoarthritis (KOA) by 18F-fluorodeoxyglucose (18F-FDG) small-animal positron emission tomography (PET) and micro-computed tomography (CT) imaging.Methods: KOA was induced in rats by intra-articular injection MIA (2 mg/50 μL) through the right knee of the rats. Forty male Sprague Dawley rats weighing 280 to 340 g (12 weeks old) were randomly divided into four groups including Control group, KOA group, KOA plus manual acupuncture group (KOA+MA), KOA plus sham acupuncture group (KOA+SA). The acupuncture treatment lasted for three weeks (one-day rest after six days of treatment). Paw withdrawal threshold test and open-field test were used to assess mechanical allodynia and locomotor activity respectively for once a week. Hematoxylin and eosin (H&E) staining was used to assess the damage of the cartilage, synovium and infrapatellar fat pad (IFP). 18F-FDG PET was performed to quantify joint inflammation. The influence on the subchondral bone in these rats was confirmed by micro-CT.Results: Mechanical hyperalgesia, joint inflammation, and obvious bone destruction were observed in the KOA group

Published
2022

42. Acupuncture reduces pain in rats with osteoarthritis by inhibiting MCP2/CCR2 signaling pathway

Author

Li Jia, Cai Guowei, Huang Zhongsheng, Tan Qian, Bocun Li, Chen Jianyi, Zhou Xiaohong, and Li Jing

Subjects
Cartilage, Articular, Male, CCR2, Knee Joint, Receptors, CCR2, Alternative therapy, Acupuncture Therapy, Pain, Osteoarthritis, Bioinformatics, General Biochemistry, Genetics and Molecular Biology, Rats, Sprague-Dawley, 03 medical and health sciences, 0302 clinical medicine, Ganglia, Spinal, Nerve Growth Factor, Acupuncture, Animals, Medicine, Spiro Compounds, Receptor, trkA, Chemokine CCL2, Original Research, Neurons, 030203 arthritis & rheumatology, Mechanism (biology), business.industry, Synovial Membrane, medicine.disease, Benzoxazines, Hyperalgesia, Cytokines, Inflammation Mediators, Signal transduction, business, 030217 neurology & neurosurgery, Signal Transduction
Abstract

Acupuncture is an emerging alternative therapy that has been beneficial for the pain of osteoarthritis (OA). However, the underlying mechanism of protective effect remains unclear. MCP1/CCR2 axis can be stimulated in various periods of OA, and we hypothesize that acupuncture may treat OA by regulating the MCP1/CCR2 axis. This study aimed to explore the effect of acupuncture at points ST35 and ST36 on the effects of hyperalgesia and cartilage in OA rats including the expression of chemokines, nerve growth factor (NGF), and inflammatory-related proteins. OA was induced in male Sprague–Dawley rats by anterior cruciate ligament transection at the right knee. The first acupuncture intervention was performed on the seventh day after surgery and once a day for seven weeks. The knee-pain-related behaviors, histology, and related protein were examined in this study. We have found that electroacupuncture at ST35 and ST36 can significantly alleviate the hyperalgesia and cartilage degeneration as well as reducing nerve sprouting in OA knee joint. Moreover, acupuncture treatment may inhibit the MCP1/CCR2 axis as well as down-regulate inflaming factor and NGF in cartilage and synovial tissue. The data presented here indicate that acupuncture exerts a protective effect against hyperalgesia and cartilage degeneration, and the mechanism might involve in chemokines and NGF pathway.

Published
2020

43. Additional file 1 of Mining and characterization of the PKS–NRPS hybrid for epicoccamide A: a mannosylated tetramate derivative from Epicoccum sp. CPCC 400996

Author

Zhang, Tao, Cai, Guowei, Rong, Xiaoting, Xu, Jingwen, Jiang, Bingya, Wang, Hao, Li, Xinxin, Wang, Lu, Zhang, Ran, He, Wenni, and Yu, Liyan

Abstract

Additional file 1: Table S1. NMR Data for epicoccamide A (1). Table S2. Comparison of the signature residues for amino acid selection by adenylation (A) domains of fungal PKS-NRPS (NRPS). Figure S1. The 1H NMR spectrum of compound 1. Figure S2. The 13C NMR spectrum of compound 1. Figure S3. The 1H-1H COSY spectrum of compound 1 (in DMSO). Figure S4. The HSQC spectrum of compound 1 (in DMSO). Figure S5. The HMBC spectrum of compound 1 (in DMSO). Figure S6. HRESIMS spectrum of compound 1. Figure S7. ESI MS/MS (-) spectrum of compound 1.

Published
2022
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