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A System Identification-based Modeling Framework of Bidirectional DC-DC Converters for Power Grids

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Journal of Modern Power Systems and Clean Energy 2022年第3期10卷 788-799页

作者： Gabriel E.Mejia-Ruiz Mario R.A.Paternina Juan R.Rodriguez R. Juan M.Ramirez Alejandro Zamora-Mendez Guillermo Bolivar-O. Department of Electrical Engineering National Autonomous University of Mexico(UNAM)Mexico CityMexico Department of Electrical Engineering Center for Research and Advanced Studies(CINVESTAV)GuadalajaraMexico Electrical Engineering Faculty Michoacan University of Saint Nicholas of Hidalgo(UMSNH)MoreliaMexico Engineering Faculty Corporacion Universitaria Minuto de Dios-UNIMINUTOBelloColombia

This paper proposes a system identification framework based on eigensystem realization to accurately model power electronic *** proposed framework affords an energy-based optimal reduction method to precisely identify the dynamics of power electronic converters from simulated or actual raw data measured at the converter’s *** method does not require any prior knowledge of the topology or internal parameters of the converter to derive the system modal *** accuracy and feasibility of the proposed method are exhaustively evaluated via simulations and practical tests on a software-simulated and hardware-implemented dual active bridge(DAB)converter under steady-state and transient *** various comparisons with the Fourier series-based generalized average model,switching model,and experimental measurements,the proposed method attains a root mean square error(RMSE)of less than 1%with respect to the actual raw ***,the computational effort is reduced to 1/8.6 of the Fourier series-based model.

关键词： Dual active bridge eigensystem realization algorithm generalized average model power electronic converter identification

Modal parameter identification for a roof overflow powerhouse under ambient excitation

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Water Science and Engineering 2016年第1期9卷 67-80页

作者： Yan Zhang Ji-jian Lian Fang Liu State Key Laboratory of Hydraulic Engineering Simulation and Safety Tianjin UniversityTianjin 300072China State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin China Institute of Water Resources and Hydropower ResearchBeijing 100038China

Modal parameter identification is a core issue in health monitoring and damage detection for hydraulic structures. For a roof overflow hydropower station with a bulb tubular unit under ambient excitation, a complex unit-powerhouse-dam coupling vibration system increases the difficulties of modal parameter identification. In this study, in view of the difficulties of modal order determination and the noise jamming caused by ambient excitation, along with false mode identification and elimination problems, the ensemble empirical mode decomposition （EEMD） method was used to decrease noise, the singular entropy increment spectrum was used to determine system order, and multiple criteria were used to eliminate false modes. The eigensystem realization algorithm （ERA） and stochastic subspace identification （SSI） method were then used to identify modal parameters. The results show that the relative errors of frequencies in the first four modes were within 10% for the ERA method, while those of SSI were over 10% in the second and third modes. Therefore, the ERA method is more appropriate for identifying the structural modal parameters for this particular powerhouse layout.

关键词： Hydraulic structure Order determination Ensemble empirical mode decomposition Singular entropy eigensystem realization algorithm Bulb tubular unit

Modal Identification of Offshore Platforms Using Statistical Method Based on ERA

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China Ocean Engineering 2005年第2期19卷 175-184页

作者：王树青李华军 T.Takayama Coastal and Offshore Research Institute Ocean University of China Qingdao 266071 China Kyoto University Gokasho Uji Kyoto 611-0011 Japan

Identification of modal parameters of a linear structure with output-only measurements has received much attention over the past decades. In the paper, the Natural Excitation Technique (NExT) is used for acquisition of the impulse signals from the structural responses. Then eigensystem realization algorithm (ERA) is utilized for modal identification. For disregarding the fictitious ‘computational modes', a procedure, Statistically Averaging Modal Frequency Method (SAMFM), is developed to distinguish the true modes from noise modes, and to improve the precision of the identified modal frequencies of the structure. An offshore platform is modeled with the finite element method. The theoretical modal parameters are obtained for a comparison with the identified values. The dynamic responses of the platform under random wave loading are computed for providing the output signals used for identification with ERA. Results of simulation demonstrate that the proposed method can determine the system modal frequency with high precision.

关键词： modal identification eigensystem realization algorithm statistically averaging modal frequency method offshore platform

Vibration analysis and topology optimization of the header of full-feeding rice combine harvester

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International Journal of Agricultural and Biological Engineering 2023年第4期16卷 96-108页

作者： Han Tang Changsu Xu Jianhua Zhu Rui Guan Jinwu Wang College of Engineering Northeast Agricultural UniversityHarbin 150030China School of Water Conservancy and Civil Engineering Northeast Agricultural UniversityHarbin 150030China

The header frame of full-feeding rice combine harvester was characterized by severe vibration due to the excitation force generated by the movement of each working *** order to solve the problem,the parametric model of the header frame was established,and the accuracy of the finite element model was verified by comparison of the results of the free modal analysis and free vibration modal test based on eigensystem realization algorithm(ERA).Then the constrained modal frequencies were calculated and compared with the external excitation source frequencies,the results showed that the first and eighth order modal natural frequencies were coupled with the excitation frequencies of the threshing cylinder and the engine respectively,which were apt to *** avoid resonance and achieve lightweight design,topology optimization,and finite element analysis were carried *** optimization results showed that the strength and rigidity meet the requirements and the weight was 14.17%lower than *** first and eighth order modal natural frequencies were far away from the excitation frequencies range of the threshing cylinder and engine,and the frequencies were far away from the range of each excitation frequency,which effectively avoided the occurrence of *** experiments showed that the peak value of the vibration acceleration in the three directions of the 8 measuring points of the optimized header frame was significantly reduced,which effectively reduced the vibration of the header frame during *** study provides a method for obtaining the vibration characteristics of key components of agricultural machinery and provides a reference for the weight and vibration reduction of header frames of rice,wheat,rape,and other crop combine harvesters.

关键词： eigensystem realization algorithm modal analysis free modal test topology optimization lightweight field experiment

Whole-spacecraft hybrid vibration isolation based on piezoelectric stacks and viscoelastic material

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Journal of Harbin Institute of Technology(New Series) 2011年第5期18卷 1-6页

作者：李明明方勃谭立军黄文虎 School of Astronautics Harbin Institute of Technology

In order to improve the performance of whole-spacecraft vibration isolation systems,choosing piezoelectric stacks and viscoelastic material as the active and passive vibration isolation components,an innovative whole-spacecraft hybrid vibration isolation system (WSHVIS) is designed and *** finite element method is used to establish the dynamic model of WSHVIS and analyze its frequency response *** to the analysis results,eigensystem realization algorithm is applied to obtain the minimum-order state-space model of WSHVIS,which is used to design *** this basis,off-line simulation and on-line realization for the WSHVIS is *** simulation and experimental results showed that WSHVIS can effectively reduce the vibration loads transmitted from launch vehicle to *** with passive vibration isolation system,the hybrid vibration isolation system has a significant inhibitory effect on the low-frequency vibration components,and can greatly increase the safety and reliability of spacecraft.

关键词： whole-spacecraft hybrid vibration isolation eigensystem realization algorithm finite element method piezoelectric stack actuator