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Behavior of multiple modes before and during minor disruption with the external resonant magnetic perturbations on J-TEXT tokamak

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Plasma Science and technology 2022年第6期24卷 88-95页

作者： Mingxiang HUANG Zhengkang REN Feiyue MAO Zhoujun YANG Yuan GAO Zhichao ZHANG Shunfan HE Guoliang LI Jinrong FAN Wei TIAN Nengchao WANG Zhipeng CHEN Yonghua DING Yuan PAN Zhongyong CHEN College of Computer Science South-Central Minzu UniversityWuhan 430074People's Republic of China International Joint Research Laboratory of Magnetic Confinement Fusion and Plasma Physics State Key Laboratory of Advanced Electromagnetic Engineering and TechnologySchool of Electrical and Electronic EngineeringHuazhong University of Science and TechnologyWuhan 430074People's Republic of China

The behavior of multiple modes before and during minor disruption with the external resonant magnetic perturbations(RMPs)has been studied on a J-TEXT *** main component of RMPs is m/n=2/1,where m and n are the numbers of the poloidal and toroidal modes,*** the mode-locking caused by RMPs,it is found that before a minor or a major disruption(if there is no minor disruption),strong oscillations in both electron temperature and density occur if the edge safety factor q_(a)>*** analysis shows that the oscillations are caused by the m/n=3/1 *** addition,using the ECE,Mirnov coils and 2D electron cyclotron emission imaging diagnostic systems,it is found that a thermal collapse occurs on the inner side of the 2/1magnetic island during the minor disruption,and before the collapse,a 3/2 island increases,after the collapse,the 3/2 island may ***,the study also shows that these 3/1,2/1 and 3/2modes play roles in the thermal collapse of disruptions.

关键词： oscillation multiple modes disruption

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Modeling and Cross-Timescale Mechanism Analysis of Voltage Control Impact on Electromechanical Dynamics of VSG-Controlled DFIG-Based WT

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IEEE Transactions on Energy Conversion 2024年

作者： Cai, Shiyu Li, Yingbiao Wang, Wei Zhan, Meng Huazhong University of Science and Technology State Key Laboratory of Advanced Electromagnetic Technology School of Electrical and Electronic Engineering Wuhan430074 China

With the development of doubly fed induction generator (DFIG)-based wind turbines (WTs), the application of virtual synchronous generation (VSG) concepts in DFIG control has gained attention for enhancing grid stability. The VSG-controlled DFIG system, characterized by its multiple timescale energy storage elements and control loops, presents a complex dynamic behavior of multiple timescales and there are interactions between different timescales. However, existing research mostly focuses on modeling and stability analysis of a single timescale, neglecting the cross-timescale effects. This paper presents a dynamic modeling methodology for VSG-controlled DFIG-based WTs to analyze the cross-timescale impact of voltage control on electromechanical dynamics. Firstly, cross-timescale phenomena and laws of the impact are revealed. An excitation and response dynamical model of VSG-controlled DFIG is proposed, which can provide a physical comprehension of the formation mechanisms behind cross-timescale phenomena within DFIG. Additionally, the analysis of the impact of voltage control on electromechanical dynamics is performed using the damping torque. Finally, the analyses of cross-timescale mechanisms are validated through time-domain simulations. © 2024 IEEE.

关键词： Asynchronous generators

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Transient Synchronization Stability and Enhanced-LVRT Scheme for Grid-forming Converters Considering Current Limitation and Nonlinear Damping Simultaneously

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IEEE Transactions on Energy Conversion 2024年

作者： Sun, Huiqiang Lin, Xinchun Wei, Juntian Huazhong University of Science and Technology State Key Laboratory of Advanced Electromagnetic Technology School of Electrical and Electronic Engineering Wuhan430074 China

Due to the fragile overcurrent capability, it is necessary to embed the current limitation into the control system of the grid-forming (GFM) converter. In such regard, the GFM converter undergoes the transient mode switching during low voltage ride-through (LVRT), which reshapes the power angle characteristics. Previous studies have proven that the introduction of current limitation poses challenges to transient synchronization stability. However, the impact of the unfavorable nonlinear damping, and the current limitation mode in which the current reference vector does not coincide with the coordinate axes are usually ignored. This paper reveals that two current limitation modes will appear during entering and exiting current saturation under severe grid faults, both for the d-axis priority and q-axis priority current limitation algorithm. And the modes of each fault stage during LVRT are clarified. Furthermore, the synchronization characteristics of the GFM converter under severe faults are investigated by power angle trajectories considering both current limitation and nonlinear damping. Based on intuitive physical images, a CCT calculation method is proposed to quantitatively analyze the influence of control parameters, namely active power reference and droop coefficient, on transient synchronization stability. To improve the resynchronization ability of the GFM converter after faults, an enhanced-LVRT scheme is proposed by applying the redesigned current limitation strategy. Thanks to the introduction of the power angle feedback into the current limitation, this scheme is adaptive to various large disturbance events. Finally, simulations and experiments are conducted to validate the theoretical analysis. © 2024 IEEE.

关键词： Damping

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Enhancing Resilience With Electric Vehicles Charging Redispatching and Vehicle-to-Grid in Traffic-Electric Networks

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IEEE Transactions on Industry Applications 2024年第1期60卷 953-965页

作者： Gan, Wei Wen, Jianfeng Yan, Mingyu Zhou, Yue Yao, Wei Cardiff University School of Engineering CardiffCF24 3AA United Kingdom University of Liverpool Department of Electrical Engineering and Electronics LiverpoolL69 3BX United Kingdom National Tsing Hua University Department of Electrical Engineering Hsinchu30013 Taiwan Huazhong University of Science and Technology State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Wuhan430074 China

Electric vehicles (EVs) can be viewed as both electric loads and a type of mobile storage resource. Effective management and utilization of EVs can yield significant benefits for networks. This article proposes a novel resilience enhancement method for coupled traffic-electric networks with a high penetration of EVs, incorporating two specific strategies in response to contingencies. The first strategy involves rerouting and reselecting charging stations for power-deficient EVs, while the second entails redispatching power-sufficient EVs to the most suitable nearby charging stations to provide grid support through vehicle-to-grid technology. A carefully designed pricing mechanism, which includes imposing additional road congestion tolls and charging station charging fees, is incorporated to facilitate rerouting and charging station reselection for EVs under the user equilibrium principle. Furthermore, a formulation incorporating the two proposed resilience enhancement strategies for coupled traffic-electric networks is presented. This formulation enables coordination between the two networks to capitalize on flexibility derived from sector coupling. A series of linearization techniques are then introduced to transform the original problem into a mixed-integer quadratically constrained programming model. Numerical results based on a coupled network with 20 traffic roads and 21 electric buses are presented to demonstrate the effectiveness of the proposed resilience enhancement method. © 1972-2012 IEEE.

关键词： Convex optimization

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Synchronous Vibration Suppression of Magnetic Bearing Systems without Angular Sensors

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CES Transactions on Electrical Machines and Systems 2021年第1期5卷 70-77页

作者： Hongbo Sun Dong Jiang Jichang Yang State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and TechnologyWuhan 430074China

Active Magnetic Bearing(AMB)levitates rotor by magnetic force without friction,and it can provide active control force to suppress vibration while *** of vibration suppressing methods need angular speed sensors to obtain rotating speed,but in many occasions,angular speed sensor is difficult to install or is difficult to guarantee *** paper proposed a vibration suppressing strategy without angular speed sensor based on generalized integrator and frequency locked loop(GI-FLL)and phase shift generalized integrator(PSGI).GI-FLL and high-pass filter estimate frequency from control current,PSGI is applied to generate compensating ***,model of AMB system expressed by transfer function is established and effect of centrifugal force is ***,principle and process of vibration suppressing strategy is *** of parameters are analyzed by root locus and bode *** results display the process of frequency estimation and performance of *** are carried on a test rig,results of simulations and experiments demonstrate the effectiveness of proposed vibration suppressing strategy.

关键词： Active Magnetic Bearing(AMB) vibration suppression frequency estimation phase shift generalized integrator(PSGI)

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Observation of the Space Leader during the Attachment Process in Positive laboratory Sparks 12

Observation of the Space Leader during the Attachment Proces...

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12th Asia-Pacific International Conference on Lightning, APL 2023

作者： Wang, Xiankang Liu, Xiaopeng Li, Zijian Yao, Yao He, Junjia Electric Power Research Institute State Grid Hubei Electric Power Co. Ltd. Wuhan China Huazhong University of Science and Technology State Key Laboratory of Advanced Electromagnetic Engineering and Technology Wuhan China

ISBN: (纸本)9781665456852

A long-standing but fundamental question in lightning and laboratory spark researches is how the positive and negative leader attach with each other. Here we report optical images and discharge current waveforms during the breakthrough phase of attachment process in positive laboratory sparks. The space leader inside the common streamer zone was observed for the first time. The recorded electric current as well as the calculated impedance of the common streamer zone reveal the evolution process of the space leader. Finally, a new scenario including three subsequent stages is proposed for leaders' attachment process. © 2023 IEEE.

关键词： Laboratories

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Comparative Study of CCPS Based on Permanent Magnet and Electrically Excited HIA for Selecting Rational Topological Structure

CPSS Transactions on Power Electronics and Applications

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CPSS Transactions on Power Electronics and Applications 2025年第1期10卷 66-84页

作者： Longjian Liu Kexun Yu Xianfei Xie Zhijian Liu Faculty of Electric Power Engineering Kunming University of Science and Technology Kunming China State Key Laboratory of Advanced Electromagnetic Technology Huazhong University of Science and Technology Wuhan China

In order to facilitate the selection of an optimal topological structure for rational pulsed capacitor charging power supplies (CCPS), this paper presents a comparative analysis of CCPS based on permanent magnet excited (PME) and electrically excited (EE) homopolar inductor alternators (HIA). The findings indicate that the d-axis transient inductance of the PME HIA is marginally greater than that of the EE HIA, a result that contradicts initial expectations. Notably, the PME HIA does not require consideration of transient flux variations, whereas the EE HIA does. The study establishes relationships among the enhancement of charge performance, efficiency, capacitance, frequency, and field winding (FW) resistance. It is observed that as capacitance, frequency, and FW resistance increase, there is a corresponding improvement in charge performance. The equipotential line representing the enhancement of charge performance approximates an inverse proportional function, suggesting that if the product of FW resistance and capacitance, or the product of FW resistance and frequency, remains constant, the improvement in charge performance will also be constant. Furthermore, it is noted that as capacitance and frequency increase, the improvement in efficiency diminishes, which is contrary to the trend observed in charge performance. To comprehensively evaluate the enhancement of charge performance and efficiency, a weighted function is proposed. This function aids in the selection of a rational topological structure for CCPS, distinguishing between those based on PME HIA and those based on EE HIA. Based on the results derived from the weighted improvement analysis, appropriate topological structures for CCPS can be identified according to varying capacitance, frequency, and FW resistance. Specifically, when the product of capacitance and FW resistance, or the product of frequency and FW resistance, is substantial, the PME HIA is recommended; conversely, the EE HIA is preferred

关键词： Transient analysis Resistance Capacitance Inductance Capacitors Power system measurements Density measurement Magnetic fields Windings Iron

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Junction Temperature Estimation Method for Press-pack IGBTs Using Double-side Thermal Resistance Network Model

Junction Temperature Estimation Method for Press-pack IGBTs ...

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2024 CPSS and IEEE International Symposium on Energy Storage and Conversion, CPSS and ISESC 2024

作者： Tu, Liuyu Liang, Lin Wang, Li Zhang, Ziyang Zhang, Zhiyuan Wen, Kaijun School of Electrical and Electronic Engineering Engineering Research Center of Power Safety and Efficiency State Key Laboratory of Advanced Electromagnetic Technology Ministry of Education of China Huazhong University of Science and Technology Wuhan China CTG Jiangsu Energy Investment Co. Ltd Nanjing China

ISBN: (纸本)9798350380514

Due to the asymmetry of the double-side structure of press-pack insulated-gate bipolar transistors (PP IGBTs), the physical significance and calculation method of parameters in the thermal resistance network model are not clear, which brings some challenges to the junction temperature (Tj) estimation method using this model. In this paper, two kinds of double-side thermal resistance network physical models are proposed by calculating the heat flow ratio on both sides and taking the temperature of the top and bottom case as the reference isothermal point. In the single chip packaging and double-side water cooling conditions, the simulation results show that the maximum relative error of the junction temperature estimation of two kinds of models established and the traditional model is -0.13%, 1.21% and -1.42%, respectively. The experiment also verifies that the proposed model has the highest accuracy and a certain range of application for the junction temperature estimation of PP IGBTs. © 2024 IEEE.

关键词： Insulated gate bipolar transistors (IGBT)

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Forecasting Scenario Generation for Multiple Wind Farms Considering Time-series Characteristics and Spatial-temporal Correlation

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Journal of Modern Power Systems and Clean Energy 2021年第4期9卷 837-848页

作者： Qingyu Tu Shihong Miao Fuxing Yao Yaowang Li Haoran Yin Ji Han Di Zhang Weichen Yang State Key Laboratory of Advanced Electromagnetic Engineering and Technology Hubei Electric Power Security High Efficiency Key Laboratory School of Electrical and Electronic EngineeringHuazhong University of Science and TechnologyWuhanChina Department of Electrical Engineering Tsinghua UniversityBeijingChina

Scenario forecasting methods have been widely studied in recent years to cope with the wind power uncertainty problem. The main difficulty of this problem is to accurately and comprehensively reflect the time-series characteristics and spatial-temporal correlation of wind power generation. In this paper, the marginal distribution model and the dependence structure are combined to describe these complex characteristics. On this basis, a scenario generation method for multiple wind farms is proposed. For the marginal distribution model, the autoregressive integrated moving average-generalized autoregressive conditional heteroskedasticity-t (ARIMA-GARCH-t) model is proposed to capture the time-series characteristics of wind power generation. For the dependence structure, a time-varying regular vine mixed Copula (TRVMC) model is established to capture the spatial-temporal correlation of multiple wind farms. Based on the data from 8 wind farms in Northwest China, sufficient scenarios are generated. The effectiveness of the scenarios is evaluated in 3 aspects. The results show that the generated scenarios have similar fluctuation characteristics, autocorrelation, and crosscorrelation with the actual wind power sequences.

关键词： Scenario generation wind farm regular vine Copula spatial-temporal correlation time-series characteristics

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Power System Transient Stability Prediction Based on GWO-SVM and Boosting Method 17th

Power System Transient Stability Prediction Based on GWO-SVM...

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17th Annual Conference of China Electrotechnical Society, CES 2022

作者： Ao, Yuqi Chen, Jinfu Cai, Defu Liu, Haiguang Chen, Rusi State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China Electric Power Research Institute State Grid Hubei Electric Power Co. Ltd. Wuhan China

ISBN: (纸本)9789819903566

As various undesirable features such as intermittency, randomness and low inertia have been introduced into power system operation and control, it is imperative to develop efficient transient stability prediction (TSP) schemes. In view of the wide application of data mining technology, this paper proposes a data-driven method for TSP based on support vector machine (SVM) and ensemble learning. Firstly, grey wolf optimization (GWO) algorithm is introduced to select optimal hyperparameters of SVM. By approaching the selected position in every iteration, the constraint coefficient and balance factor are updated constantly and finally reach the fit values in search space. Moreover, an improved boosting method is applied to enhance the model performance, prediction results become more accurate and robust based on the combination of basic classifiers. Then, for the sake of filtering out the unreliable predictions, a trusted domain is set according to the distance between test sample and discriminant boundary. Finally, case studies on the IEEE 39-bus system illustrate the effectiveness of the proposed methodology. © 2023, Beijing Paike Culture Commu. Co., Ltd.

关键词： Support vector machines

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