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SSRN 2023年

作者： Liu, Zhichang Yin, Xianggen Yin, Xin Lu, Qinghui Qiao, Jian Wang, Yikai State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan430074 China School of Automation Wuhan University of Technology Wuhan430070 China

Due to the shortage of fossil energy resources and the energy transformation, the installed capacity of photovoltaic (PV) power supply has been steadily increasing, which brings the problem of the low sensitivity of the PV transmission line segregated-phase current ratio differential protection. Furthermore, there are cases of large-scale gigawatt-level PV power supply centralized integration into the 500kV grid, bringing new challenges to the security and stability of the grid. In this paper, according to the fault characteristics of photovoltaic power supply, the current phase characteristics on both sides of the line are quantitatively analyzed when an internal fault occurs with transition resistance, and then the phase and amplitude differences of the currents on both sides of the line are used to propose a Dice similarity coefficient-based pilot protection method for photovoltaic transmission lines. PSCAD/EMTDC simulation results show that the proposed method can accurately identify internal faults under the conditions of different fault locations, fault types, transition resistances, line lengths, PV power supply capacity, and levels of noise. Additionally, the proposed method has a fast operation speed and a great performance to transition resistance. © 2023, The Authors. All rights reserved.

关键词： Electric lines

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A three parallel branches harmonic model with adaptive capability of operating state variation

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International Journal of Electrical Power and Energy Systems 2025年 169卷

作者： Yang, Youhang Wang, Shaorong Ren, Jiaxuan Guo, Yao Chen, Siyuan Shi, Mingming Zheng, Xian State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan430074 China Department of Electrical Engineering Tsinghua University Beijing100084 China Electric Power Research Institute of State Grid Jiangsu Electric Power Company Nanjing210000 China

The wide application of power electronic equipment has exacerbated the harmonic distortion in power systems. More accurate harmonic models are urgently needed to evaluate and mitigate harmonic issues. To address this challenge, we propose a three parallel branches model (TPBM) with adaptive capability of operating state variation. Firstly, the accuracy of current general harmonic models is analyzed through Taylor expansion. Secondly, the structure of TPBM is proposed and a parameter calculation method is provided for individual operating state. TPBM comprehensively incorporates the effects of variations in different order voltages and characteristic parameters of harmonic source with respect to the steady-state operating point, and theoretically can achieve higher accuracy than traditional models. Furthermore, an adaptive TPBM for harmonic source operating state variations based on Stacking ensemble learning technology is proposed, the construction process and training strategy of the Stacking model are also elaborated. Finally, simulations and experiments are conducted to validate the effectiveness and accuracy of the proposed method. The results demonstrate that the adaptive TPBM exhibits enhanced adaptability to variations in harmonic source operating states and achieves superior estimation accuracy for harmonic currents compared to the crossed frequency admittance matrix model and the complex partial least squares method under both single and multiple operating conditions. © 2025 The Authors

关键词： Power electronic equipment Harmonic distortion Operating state variation Adaptive harmonic model Stacking ensemble learning

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Vsc-Hvdc Traveling Wave Protection Based on Fault Information Supplement Strategies

SSRN

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SSRN 2023年

作者： Zhao, Zhenting Chen, Tiantian Duan, Xianzhong Li, Yinhong State Key Laboratory of Advanced Electromagnetic Engineering and Technology Hubei Electric Power Security and High Efficiency Key Laboratory School of Electrical and Electronic Engineering Huazhong University of Science and Technology Hubei Wuhan430074 China

The VSC-HVDC (Voltage Source Converter based High Voltage Direct Current Transmission) traveling wave protection, relying on single-end information, has a limited ability to identify boundary faults. To improve this problem, two fault information supplement strategies are suggested. According to the bipolar symmetry of the fault traveling wave, the measurement of one pole is supplemented by that of the other. According to the reactor characteristics, i.e., the proportional relationship between the voltage and the current change rate of the DC (Direct Current) reactor, the voltage measurement is further supplemented. The VSC-HVDC traveling wave protection based on the fault information supplement strategies is proposed. The sensitivity for identifying the high-resistance boundary fault is significantly improved. The protection performance and applicability are validated on the four-terminal VSC-HVDC simulation model based on PSCAD/EMTDC. © 2023, The Authors. All rights reserved.

关键词： HVDC power transmission

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Automatic Generation of Topology Diagrams for Strongly-Meshed Power Transmission Systems

arXiv

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arXiv 2023年

作者： Wang, Jingyu Chen, Jinfu Shi, Dongyuan Duan, Xianzhong The State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan China The College of Electrical and Information Engineering Hunan University Changsha China

Topology diagrams are widely seen in power system applications, but their automatic generation is often easier said than done. When facing power transmission systems with strongly-meshed structures, existing approaches can hardly produce topology diagrams catering to the aesthetics of readers. This paper proposes an integrated framework for generating aesthetically-pleasing topology diagrams for power transmission systems. Input with a rough layout, the framework first conducts visibility region analysis to reduce line crossings and then solves a mixed-integer linear programming problem to optimize the arrangement of nodes. Given that the complexity of both modules is pretty high, simplification heuristics are also proposed to enhance the efficiency of the framework. Case studies on several power transmission systems containing up to 2,046 nodes demonstrate the capability of the proposed framework in generating topology diagrams conforming to aesthetic criteria in the power system community. Compared with the widespread force-directed algorithm, the proposed framework can preserve the relative positions of nodes in the original layout to a great extent, which significantly contributes to the identification of electrical elements on the diagrams. Meanwhile, the time consumption is acceptable for practical applications. © 2023, CC BY-NC-SA.

关键词： Topology

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Optimization Scheduling Strategy for Microgrids with Orderly EV Charging Based on Information-Gap Decision Theory

Optimization Scheduling Strategy for Microgrids with Orderly...

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Power engineering (ICPE), International Conference on

作者： Dongjunming Yang Xinrui Xiong Rui Ma Suhua Lou Guanzhen Wang Zheng Lin Power Grid Planning & Research Center Guizhou Power Grid Co. Ltd Guiyang China State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China

ISBN: (数字)9798331531140

ISBN: (纸本)9798331531157

As renewable energy rapidly develops, microgrids have gradually become an essential part of modern power systems. Microgrids integrate distributed generation, energy storage systems, and loads, improving energy utilization efficiency and offering strong resilience against disturbances. Electric vehicles (EVs), as a form of energy storage for renewable energy, have a significant impact on the operation of microgrids through their charging behavior. Proper scheduling of EV charging can not only reduce the operating costs of the microgrid but also balance loads and enhance renewable energy absorption. However, the uncertainty in DG output poses challenges to microgrid scheduling. The Information-Gap Decision Theory (IGDT) is an approach used to solve optimization problems involving uncertainty. Compared to traditional methods for handling uncertainty, such as stochastic programming, fuzzy programming, and interval robust optimization, IGDT has the advantage of not requiring precise probability distributions or uncertainty intervals for uncertain parameters. This paper proposes an optimization scheduling strategy for microgrids with orderly charging of EVs based on IGDT, analyzing the uncertainty of DG output. First, a model of EV travel characteristics and an orderly charging scheduling model are established. Then, a robust optimization model based on IGDT is constructed. The objective is to minimize the total operating cost of the microgrid.

关键词： Renewable energy sources Uncertainty Costs Decision theory Microgrids Programming Electric vehicle charging Filling Robustness Optimization

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Effect of 2/1 Tearing Mode on Radiation Asymmetry During Disruptions on J-Text

SSRN

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SSRN 2023年

作者： Liu, FanXi Yan, Wei Chen, Chen Zhong Li, You Fang, Jiangang Mao, Feiyue Ren, Zhengkang Zhao, Chuanxu Li, Yangbo Zhong, Yu Li, Feng Zou, Guinan Zhang, Weikang Yu, Yinlong Nie, Zisen Yang, Zhoujun Wang, Nengchao Chen, Zhipeng Ding, Yonghua International Joint Research Laboratory of Magnetic Confinement Fusion and Plasma Physics State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan430074 China

Plasma disruption in the tokamak is a huge threat to the safe operation of ITER, which will cause serious damage to the tokamak device. At present, massive impurity injection is the main disruption mitigation method, include massive gas injection (MGI) and shattered pellet injection (SPI) which can dissipate most of the internal thermal energy via radiation. However, radiation asymmetry will still cause damage to the device when it results the concentration of radiation in a small area. It has been observed on many devices that n=1 mode has a strong influence on radiation asymmetry. In this paper, the experimental results of radiation asymmetry on J-TEXT tokamak have been introduced, and there is a sine function relationship between toroidal peaking factor (TPF) and the phase of 2/1 tearing mode. It is found that when the injection position is aligned with the X-point of the pre-existing magnetic island, TPF has the maximum value, and while the injection position is between the X-point and the O-point, TPF has the minimum value. This will be helpful for the study of disruption mitigation of future large devices. © 2023, The Authors. All rights reserved.

关键词： Tokamak devices

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Partial Discharge Characteristic of Different Defects at Generator Stator End-winding 10

Partial Discharge Characteristic of Different Defects at Gen...

引用

10th China International Conference on Electricity Distribution, CICED 2022

作者： Chen, Yihong Jia, Shiyuan Peng, Xiaosheng Zhou, Jin Zhang, Yue Li, Cong State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan China China-EU Institute for Clean and Renewable Energy Huazhong University of Science and Technology Wuhan China Dongfang Electric Machinery CO. LTD. Deyang China

ISBN: (数字)9781665452687

ISBN: (纸本)9781665452687

Partial Discharge (PD) monitoring is one of the main methods to evaluate the insulation condition of generator stators to avoid insulation failure. Difference of PD characteristics of different defect types at the generator stator end-winding is be analyzed in this paper, which can provide a basis for PD pattern recognition. Three typical artificial defects were created on generator stator end-winding samples, including end-winding contamination, corona at the junction of the grading paint, and defect in slot exit. High voltage testing is carried out on these three defect models to obtain the PD phase characteristic maps of different kinds of defects at the stator end-winding. The results show that the PD characteristic of different types of defect show obvious differences, among which the discharge of end-winding contamination is the smallest, the PD characteristic pattern of defect at the junction of the grading paint is wing-shaped, the discharge amount of the slot exit defect is the largest, and the PD patterns show layered characteristics. By analyzing the characteristics of the Phase Resolved Partial Discharge (PRPD) patterns of three different defects, it is expected to serve as a basis for the PD pattern recognition at the stator end-winding and ensure the safe operation of the generator set. © 2022 IEEE.

关键词： Partial discharges

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A Multi-Frequency Reflector Base Station Antenna With Enhanced Beam Scanning Capabilities for 6G

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IEEE Antennas and Wireless Propagation Letters 2025年

作者： Xie, Yujie Wang, Zhengpeng Li, Yujian Miao, Jungang Gao, Steven Electromagnetic Laboratory School of Electronic and Information Engineering Beijing100191 China Beijing Jiaotong University Institute of Lightwave Technology and the Key Laboratory of All Optical Network and Advanced Telecommunication Network Ministry of Education Beijing100044 China Chinese University of Hong Kong Department of Electronic Engineering Hong Kong

This letter presents a multi-frequency base station antenna with enhanced beam scanning capabilities for high data rate 6 G communication. The antenna consists of a dual-polarized multi-frequency feed and a novel dual-cylindrical reflector antenna (DCRA). Through the rotation of the sub-reflector, which is illuminated by the feed, the beam can be scanned across a wide angle along the planar cylindrical orientation of the main reflector. This scanning process results in a beam scanning angle that is roughly twice the rotation angle of the sub-reflector. The phase center of the reflected beam from the sub-reflector is designed to coincide with the focal line of the main reflector, enabling two-dimensional focusing of the beam without loss of the scanning angle. A concise design formula based on the described antenna structure is derived, enabling the entire antenna design to follow a clear design flowchart, which incorporates a rapid method for determining the focal length product and focal point locations using near-field Fast Fourier Transform (FFT). The designed antenna achieves ±20° beam scanning coverage at 45 GHz, 100 GHz, and 220 GHz, with a gain exceeding 50 dBi at 220 GHz. Both simulation and experimental results validate the effectiveness of the proposed method. © 2002-2011 IEEE.

关键词： Antenna reflectors

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Model Improvement and Analysis of Nbi Power Supply Under Breakdown Condition

SSRN

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SSRN 2023年

作者： Zhang, Hongqi Li, Zhiheng Ma, Shaoxiang Guo, Jiong Zhang, Ming Pan, Yuan International Joint Research Laboratory of Magnetic Confinement Fusion and Plasma Physics State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan430074 China

Breakdown commonly occurs in the acceleration grids of the NBI system. It will cause destructive effects on the accelerating grids, and the generated transient overvoltage and current will threaten the normal operation of the acceleration grid power supply (AGPS). Therefore, it is very necessary to model the circuit to analyze the effects of breakdown on the NBI system. However, the current models are not accurate enough and are likely to have insufficient knowledge of the consequences of breakdown. In this paper, a series of improvements are made to the model by analyzing in detail the change process of AGPS during breakdown and correcting the model parameters in conjunction with the existing AGPS design scheme. Subsequently, the key indicators of the NBI system under breakdown are listed. The impact of breakdown and the need for some protection are assessed based on the results of these indicators. The results of this paper are instructive for the design and breakdown protection of future NBI systems. © 2023, The Authors. All rights reserved.

关键词： Timing circuits

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Study on the Morphology Change of Acid-Resistant Core Rods of Composite Insulators Under Acid-Heat Condition 16th

Study on the Morphology Change of Acid-Resistant Core Rods o...

引用

16th Annual Conference of China Electrotechnical Society, ACCES 2021

作者： Peng, Junzhe Lu, Ming Zhang, Dandan Gao, Chao Pan, Wenwu Zhang, Yupeng Cai, Xiang Wan, Zhiyu State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Luoyu Road 1037 Wuhan China Henan Key Laboratory of Power Transmission Line Galloping Prevention and Control Technology State Grid Henan Electric Power Research Institute Songshan South Road 85 Zhengzhou China

ISBN: (纸本)9789811918698

The nitric acid generated by partial discharge and the temperature rise caused by heat are the main deterioration factors of the composite insulator core rod during operation. This paper considers the influence of temperature changes in the degradation test of the nitric acid corroded core rod, and carries out the acid-heat degradation test of the acid-resistant core rod with different test temperature, nitric acid concentration, and deterioration time. And through macro analysis and micro analysis methods based on SEM and CLSM, comparative analyzing the morphological differences between the intact core rod, the acid etching core rod at room temperature, the acid-heat degraded core rod and the actual decay-like core rod. The macroscopic and microscopic morphology observation results show that the glass fiber of the acid-resistant core rod after acid etching at room temperature does not appear to be significantly broken. And the acid-resistant core rod after acid-heat deterioration has a serious deterioration process of glass fiber breakage and degradation of the epoxy resin matrix. It is proved that the temperature increase will accelerate the process of nitric acid corrosion of the core rod. The comparison of morphology shows that the acid-heat deterioration core rod and the actual decay-like core rod have more consistent characteristics in the macroscopic and microscopic morphologies. The acid-heat deterioration test method can better simulate the actual aging process of the core rod, and provide a direction for explaining the decay-like fracture mechanism of composite insulators. © 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

关键词： Nitric acid

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