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Transient Stability analysis of Grid-connected Converters in Wind Turbine Systems Based on Linear Lyapunov Function and Reverse-time Trajectory

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Journal of Modern Power Systems and Clean Energy 2024年第3期12卷 782-790页

作者： Mohammad Kazem Bakhshizadeh Sujay Ghosh Guangya Yang ?ukasz Kocewiak ?rsted Wind Power A/S the Technical University of Denmark

As the proportion of converter-interfaced renewable energy resources in the power system is increasing, the strength of the power grid at the connection point of wind turbine generators(WTGs) is gradually weakening. Existing research has shown that when connected with the weak grid, the stability of the traditional grid-following controlled converters will deteriorate, and they are prone to unstable phenomena such as oscillation. Due to the limitations of linear analysis that cannot sufficiently capture the stability phenomena, transient stability must be investigated. So far, standalone time-domain simulations or analytical Lyapunov stability criteria have been used to investigate transient stability. However, the time-domain simulations have proven to be computationally too heavy, while analytical methods are difficult to formulate for larger systems, require many modelling assumptions, and are often conservative in estimating the stability boundary. This paper proposes and demonstrates an innovative approach to estimating the transient stability boundary via combining the linear Lyapunov function and the reverse-time trajectory technique. The proposed methodology eliminates the need of time-consuming simulations and the conservative nature of Lyapunov functions. This study brings out the clear distinction between the stability boundaries with different post-fault active current ramp rate controls. At the same time, it provides a new perspective on critical clearing time for wind turbine systems. The stability boundary is verified using time-domain simulation studies.

关键词： Power system stability Trajectory Stability criteria Transient analysis Dynamical systems time-domain analysis Wind turbines

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Dynamic Coupling analysis of Semisubmersible Platform Float-over Method for Docking Case

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Journal of Ocean University of China 2024年第2期23卷 345-357页

作者： DING Hongyan QIN Licheng ZHANG Puyang SONG Zhengrong XIE Weiwei State Key Laboratory of Hydraulic Engineering Simulation and Safety Tianjin UniversityTianjin 300072China Offshore Oil Engineering Co. Ltd.Tianjin 300461China

In this paper,the multi-body coupled dynamic characteristics of a semisubmersible platform and an HYSY 229 barge were investigated.First,coupled hydrodynamic analysis of the HYSY 229 barge and the semisubmersible platform was performed.Relevant hydrodynamic parameters were obtained using the retardation function method of three-dimensional frequency-domain potential flow theory.The results of the hydrodynamic analysis were highly consistent with the test findings,verifying the accuracy of the multifloating hydrodynamic coupling analysis,and key hydrodynamic parameters were solved for different water depths and the coupling effect.According to the obtained results,the hydrodynamic influence was the largest in shallow waters when the coupling effect was considered.Furthermore,the coupled motion equation combined with viscous damping,fender system,and mooring system was established,and the hydrodynamics,floating body motion,and dynamic response of the fender system were analyzed.Motion analysis revealed good agreement among the surge,sway,and yaw motions of the two floating bodies.However,when the wave period reached 10 s,the motion of the two floating bodies showed severe shock,and a relative motion was also observed.Therefore,excessive constraints should be added between the two floating bodies during construction to ensure construction safety.The numerical analysis and model test results of the semisubmersible platform and HYSY 229 barge at a water depth of 42 m and sea conditions of 0°,45°,and 90° were in good agreement,and the error was less than 5%.The maximum movement of the HYSY 229 barge reached 2.61 m in the sway direction,whereas that of the semisubmersible platform was 2.11 m.During construction,excessive constraints should be added between the two floating bodies to limit their relative movement and ensure construction safety.

关键词： float-over method semisubmersible platform coupling hydrodynamic fender system time-domain analysis

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Improved Leap-frog Method for time-domain Fault Location

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Journal of Modern Power Systems and Clean Energy 2024年第2期12卷 670-674页

作者： Izudin Džafić Rabih A.Jabr Faculty of Electrical Engineering University of SarajevoSarajevo 71000Bosnia and Herzegovina Department of Electrical and Computer Engineering American University of BeirutBeirut 11072020Lebanon IEEE

The partial differential equation(PDE)solution of the telegrapher is a promising fault location method among time-domain and model-based techniques.Recent research works have shown that the leap-frog process is superior to other explicit methods for the PDE solution.However,its implementation is challenged by determining the initial conditions in time and the boundary conditions in space.This letter proposes two implicit solution methods for determining the initial conditions and an analytical way to obtain the boundary conditions founded on the signal decomposition.The results show that the proposal gives fault location accuracy superior to the existing leap-frog scheme,particularly in the presence of harmonics.

关键词： Fault location leap-frog partial differential equation time-domain analysis transmission line

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time-domain analysis methodology for large-scale RLC circuits and its applications

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Science in China(Series F) 2006年第5期49卷 665-680页

作者： LUO Zuying CAI Yici Sheldon X.-D Tan HONG Xianlong WANG Xiaoyi PAN Zhu FU Jingjing Department of Computer Science and Technology Tsinghua University Beijing 100084 China College of Information Science and Technology Beijing Normal University Beijing 100875 China Department of Electrical Engineering University of California at Riverside Riverside CA92521 USA

With soaring work frequency and decreasing feature sizes, VLSI circuits with RLC parasitic components are more like analog circuits and should be carefully analyzed in physical design. However, the number of extracted RLC components is typically too large to be analyzed efficiently by using present analog circuit simulators like SPICE. In order to speedup the simulations without error penalty, this paper proposes a novel methodology to compress the time-descritized circuits resulted from numerical integration approximation at every time step. The main contribution of the methodology is the efficient structure-level compression of DC circuits containing many current sources, which is an important complement to present circuit analysis theory. The methodology consists of the following parts： 1） An approach is proposed to delete all intermediate nodes of RL branches. 2） An efficient approach is proposed to compress and back-solve parallel and serial branches so that it is error-free and of linear complexity to analyze circuits of tree topology. 3） The Y to πtransformation method is used to error-free reduce and back-solve the intermediate nodes of ladder circuits with the linear complexity. Thus, the whole simulation method is very accurate and of linear complexity to analyze circuits of chain topology. Based on the methodology, we propose several novel algorithms for efficiently solving RLC-model transient power/ground （P/G） networks. Among them, EQU-ADI algorithm of linear-complexity is proposed to solve RLC P/G networks with mesh-tree or mesh-chain topologies. Experimental results show that the proposed method is at least two orders of magnitude faster than SPICE while it can scale linearly in both time- and memory-complexity to solve very large P/G networks.

关键词： RLC circuits analog circuit analysis time-domain analysis PIG networks algorithm complexity

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ASYMMETRIC PROPAGATION OF THE FIRST ORDER ANTISYMMETRIC LAMB WAVE IN A TAPERED PLATE BASED ON time-domain analysis

ASYMMETRIC PROPAGATION OF THE FIRST ORDER ANTISYMMETRIC LAMB...

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2016年全国压电和声波理论及器件应用研讨会

作者： Shao-yong HUO Jiu-jiu CHEN State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body College of Mechanical and Vehicle Engineering Hunan University

Background, Motivation and Objective As the device that has rectifying effect on current flux, electrical diode has significantly revolutionized fundamental science and advanced technology in various aspects of our routine life. Many contributions have been devoted to the investigations on the significant rectifying phenomena of other kinds of energy. The "diode" effects of thermal flux have been studied both theoretically and experimentally. The unidirectional propagation of electromagnetic waves has realized both broken spatial inversion symmetry and broken time reversal symmetry in the artificial photonic crystals. In parallel, the asymmetric transmission for acoustic waves should be also important in ultrasonic applications, such as directional de-noise and signal detection. Especially, seldom of acoustic rectification systems concerned about high-order Lamb waves, which have been widely applied to nondestructive evaluation and ultrasonic devices due to its higher sensitivity to plate thickness, such as the fatigue evaluation of plate, ultrasonic sensors, or oscillator. Statement of Contribution/Methods In this paper, we have studied the propagation of the first order antisymmetric(A) Lamb wave in a tapered plate, which can obtain the acoustic unidirectional transmission. The eigen-mode matching theory(EMMT) method is adopted to gain the transmission spectra and the numerical simulations in time domain by the finite element(FE) method(COMSOL MULTIPHSICS) is employed to confirm the results and reveal the physical mechanism. Results The asymmetric propagation of the first order antisymmetric(A) Lamb wave can be achieved in a tapered plate. Through numerical simulation of A Lamb wave in time domain, we find that when the thickness of the waveguide abruptly decreases to below the cut-off thickness, about half of the A mode is converted into the fundamental modes symmetrical S and antisymmetrical A to pass through the defected region. Furthermore, the transmitted modes A and S are completely apart from each other

关键词： Asymmetric transmission First order antisymmetric Lamb wave Mode conversion time-domain analysis

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Seismic response of controlled structures with active multiple tuned mass dampers

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Earthquake Engineering and Engineering Vibration 2006年第2期5卷 205-213页

作者：韩兵康李春祥 College of Civil Engineering Tongji University 1239 Siping Road Department of Civil Engineering Shanghai University 149 Yanchang Road

Active multiple tuned mass dampers （referred to as AMTMD）, which consist of several active tuned mass dampers （ATMDs） with identical stiffness and damping coefficients but varying mass and control force, have recently been proposed to suppress undesirable oscillations of structures under ground acceleration. It has been shown that the AMTMD can remarkably improve the performance of multiple tuned mass dampers （MTMDs） and is also more effective in reducing structure oscillation than single ATMDs. Notwithstanding this, good performance of AMTMD （including a single ATMD illustrated from frequency-domain analysis） may not necessarily translate into a good seismic reduction behavior in the time-domain. To investigate these phenomena, a three-story steel structure model controlled by AMTMD with three ATMDs was implemented in SIMULINK and subjected to several historical earthquakes. Likewise, the structure under consideration was assumed to have uncertainty of stiffness, such as 4-15% of its initial stiffness, in the numerical simulations. The optimum design parameters of the AMTMD were obtained in the frequency-domain by implementing the minimization of the minimum values of the maximum dynamic magnification factors （DMF） of general structures with AMTMD. For comparison purposes, response analysis of the same structure with a single ATMD was also performed. The numerical analysis and comparison show that the AMTMD generally renders better effectiveness when compared with a single ATMD for structures subjected to historical earthquakes. In particular, the AMTMD can improve the effectiveness of a single ATMD for a structure with an uncertainty of stiffness of 4-15% of its initial stiffness.

关键词： structural control active multiple tuned mass dampers （AMTMD） damping time-domain analysis uncertainty of stiffness

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A FTDC TECHNIQUE TO IMPROVE THE RANGE RESOLUTION OF SHORT RANGE FMCW RADAR

A FTDC TECHNIQUE TO IMPROVE THE RANGE RESOLUTION OF SHORT RA...

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2002 3rd International Conference on Microwave and Millimeter Wave Technology

作者： Jing Yongqi He Guoyu Xu Yongbin Fang Hui Dept.Of Electronic Engineering Beijing University of Aeronautics and Astronautics

ISBN: (纸本)078037486X

＜正＞The non-linearity of VCO limits its application and deteriorates the range resolution in short-range frequency modulated continuous wave （FM/CW） radar.In this paper is presented a Fast time-domain Calibration linearization technique （FTDC） based on software by using a known length. It is confirmed by a simulated experiment in microwave non-reflective chamber.The result shows the range resolution is improved greatly and its side-lobes are reduced about 10dB effectively.

关键词： CW radar FM radar radar resolution radar computing time-domain analysis calibration linearisation techniques voltage-controlled oscillators anechoic chambers (electromagnetic) antenna radiation patterns short range FMCW radar range resolution improvement fast time-domain calibration linearization techniques VCO nonlinearity limitations range resolution deterioration FMCW radar known length software based FTDC techniques microwave nonreflective chambers side-lobe reduction

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Plane Wave Scattering by a Step on Infinite Perfect Conducting Plane Surface

Plane Wave Scattering by a Step on Infinite Perfect Conducti...

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1999 International Conference on Computational Electromagnetics and Its Applications(ICCEA’99)

作者： Jin Sun Guoqiang Zhu Lizhi Zheng Electronic ＆ Information College Wuhan University

ISBN: (纸本)0780358023

＜正＞Plane wave scattering by a three-dimensional step on infinite perfect conducting plane surface is studied in the case where the scattering problem is reduced to the frequency or time domain electric integral equation（EFIE）.The conducting surface is modeled by planar triangular patches for numerical solution and results show that the current induced by incident wave is highly perturbed because of the presence of a three-dimensional step.

关键词： electromagnetic wave scattering electric field integral equations time-domain analysis frequency-domain analysis conducting bodies method of moments plane wave scattering electromagnetic scattering infinite perfect conducting plane surface three-dimensional step discontinuity time domain frequency domain electric field integral equation EFIE planar triangular patches numerical solution

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