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4th International Symposium on Insulation and Discharge Computation for power Equipment, IDCOMPU 2023

作者： Zhang, Ning Hao, Jian Liu, Shili Zhang, Junyi Chen, Houhe Liao, Ruijin Key Laboratory of Modern Power System Simulation and Control & Renewable Energy Technology Ministry of Education Northeast Electric Power University Jilin132012 China State Key Laboratory of Power Transmission Equipment & System Security and New Technology Chongqing University Chongqing400044 China

ISBN: (纸本)9789819974122

In recent years, arcing faults inside large oil-immersed power transformers have been frequent. Suspended bubbles, as the main product of high temperature, high humidity, material aging and cracking gas production inside transformers, are one of the main causes of arcing inside transformers. However, due to the complex structure of the oil channel and the large fluctuation of the internal flow field distribution, the resulting bubble morphology evolution and movement law is not clear. In this paper, the influence of the initial position of bubbles and the relative position between bubbles on the flow field distribution is fully considered, and the dynamic behavior of suspended bubbles in oil under two fluid forms of natural oil circulation and forced oil circulation is simulated and studied by combining laminar and turbulent flow models and bubble force control equations, and the correlation mechanism between suspended bubbles and flow field distribution characteristics is analyzed. The simulation results show that the flow field in the laminar state affects the bubble aggregation and trajectory, while the turbulent state affects the bubble distortion and motion time, and a reasonable model in the simulation of bubble dynamic behavior is more beneficial to improve the simulation accuracy. © Beijing Paike Culture Commu. Co., Ltd 2024.

关键词： Flow fields

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Infrared and Visible Image Fusion Based on Res2Net-Transformer Automatic Encoding and Decoding

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Computers, Materials & Continua 2024年第4期79卷 1441-1461页

作者： Chunming Wu Wukai Liu Xin Ma Key Laboratory of Modern Power System Simulation and Control&Renewable Energy Technology School of Electrical EngineeringNortheast Electric Power UniversityJilin132012China School of Electrical Engineering Northeast Electric Power UniversityJilin132012China School of Aeronautical Engineering Jilin Institute of Chemical TechnologyJilin132022China

A novel image fusion network framework with an autonomous encoder and decoder is suggested to increase thevisual impression of fused images by improving the quality of infrared and visible light picture fusion. The networkcomprises an encoder module, fusion layer, decoder module, and edge improvementmodule. The encoder moduleutilizes an enhanced Inception module for shallow feature extraction, then combines Res2Net and Transformerto achieve deep-level co-extraction of local and global features from the original picture. An edge enhancementmodule (EEM) is created to extract significant edge features. A modal maximum difference fusion strategy isintroduced to enhance the adaptive representation of information in various regions of the source image, therebyenhancing the contrast of the fused image. The encoder and the EEM module extract features, which are thencombined in the fusion layer to create a fused picture using the decoder. Three datasets were chosen to test thealgorithmproposed in this paper. The results of the experiments demonstrate that the network effectively preservesbackground and detail information in both infrared and visible images, yielding superior outcomes in subjectiveand objective evaluations.

关键词： Image fusion Res2Net-Transformer infrared image visible image

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Research on Asymmetric Fault Location of Wind Farm Collection system Based on Compressed Sensing

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Energy Engineering 2023年第9期120卷 2029-2057页

作者： Huanan Yu Gang Han Hansong Luo He Wang Key Laboratory of Modern Power System Simulation and Control&Renewable Energy Technology Ministry of EducationNortheast Electric Power UniversityJilin132012China Qinhuangdao Power Supply Company State Grid Jibei Electric Power Co.Ltd.Qinhuangdao066099China

Aiming at the problem that most of the cables in the power collection systemof offshore wind farms are buried deep in the seabed,whichmakes it difficult to detect faults,this paper proposes a two-step fault location method based on compressed sensing and ranging *** first step is to determine the fault zone through compressed sensing,and improve the datameasurement,dictionary design and algorithmreconstruction:Firstly,the phase-locked loop trigonometric functionmethod is used to suppress the spike phenomenon when extracting the fault voltage,so that the extracted voltage valuewillnot have a large error due to the voltage ***,theλ-NIM dictionary is designed by using the node impedancematrix and the fault location coefficient to further reduce the influence of pseudo-fault ***,the CoSaMP algorithmis improved with the generalized Jaccard coefficient to improve the reconstruction *** second step is to use the ranging equation to accurately locate the asymmetric fault of the wind farm collection system on the basis of determining the fault *** simulation results show that the proposedmethod ismore accurate than the compressedsensingmethod andimpedancemethod in fault section location and fault location accuracy,the relative error is reduced from 0.75%to 0.4%,and has a certain anti-noise ability.

关键词： Offshore wind farm convergence system compression sensing ranging equation fault location

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Numerical study of a trapezoidal bypass dual throat nozzle

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Chinese Journal of Aeronautics 2023年第3期36卷 42-62页

作者： Shuai HUANG Jinglei XU Kaikai YU Yangsheng WANG Ruifeng PAN Kuangshi CHEN Yuqi ZHANG State Key Laboratory of Mechanics and Control of Aeronautics and Astronautics Structures Nanjing 210016China College of Energy and Power Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China Jiangsu Province Key Laboratory of Aerospace Power System Nanjing 210016China

Bypass Dual Throat Nozzle(BDTN)is a novel type of fluidic thrust vectoring *** improve the infrared stealth performance of BDTN,a nozzle based on BDTN is proposed and numerically *** cross-section along the x-axis of the novel nozzle becomes a trapezoid,which is named“BDTN-TRA.”The main numerical simulation results show that BDTN-TRA can produce a thrust vectoring angle when the upper or lower bypass valve is *** angle difference between the two conditions mentioned above is usually approximately 1°-2°.Even if the two bypasses are closed,BDTN-TRA can produce a small thrust vectoring angle at around 3°-5°.When the sidewall angle increases from 60°to 90°,the thrust coefficient and thrust vectoring angle under each work condition usually decrease.A larger aspect ratio indicates better *** the aspect ratio increases over 7.2,the performance of BDTN-TRA is quite close to that of BDTN with rectangular cross-sections at the same aspect *** features will benefit the control and trimming for future aircraft design,especially for the flying wing layout *** but not least,BDTN-TRA has a more extraordinary mixing performance compared with *** distributions of static temperature and axial velocity along the x-axis of BDTN-TRA with sidewall angle of 60°decrease faster than those of *** the total temperature of the inlet equals 1600 K,the static temperature difference between BDTN-TRA with sidewall angles of 60°and 90°is over 360 K at twice the length of the nozzle downstream of the nozzle exit,which is the reflection for excellent infrared stealth for the fighter.

关键词： Bypass dual throat nozzle Infrared stealth performance Mixing performance Trapezoidal cross-sections Thrust vectoring

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A Novel Directional Pilot Protection for Flexible DC Distribution Grid 9

A Novel Directional Pilot Protection for Flexible DC Distrib...

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9th Asia Conference on power and Electrical Engineering, ACPEE 2024

作者： Wei, Xiuyan Zou, Guibin Shandong University Key Laboratory of Power System Intelligent Dispatch and Control of Ministry of Education Ji'nan250061 China Northeast Electric Power University Key Laboratory of Modern Power System Simulation and Control & Renewable Energy Technology Ministry of Education Jilin132012 China

ISBN: (纸本)9798350309638

The existing directional pilot protection (DPP) is susceptible to the line distributed capacitance and the fault resistance, and mostly rely on the current limiting reactance (CLR) at the line ends. To solve the above problems, the line-mode fault component power (LFCP) based DPP is proposed for flexible DC distribution grid (FDCDG). First, the characters of LFCP are discussed under different faults. The theoretical analysis show that the polarity of the LFCP under internal fault is same, while the polarity of the LFCP is opposite under external fault. Then, the LFCP is built as the directional criterion, and the corresponding protection scheme is constructed. The electromagnetic transient simulations of the PSCAD/EMTDC verify that the proposed DPP is less affected by the noise, and has low requirement on the sampling rate, strong engineering applicability. © 2024 IEEE.

关键词： Electric power distribution

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Zero-phase CARIMA Filtering and Application in Wind-storage system Sizing and power Dispatch Optimization

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CSEE Journal of power and Energy systems 2024年第6期10卷 2283-2295页

作者： Wei Wang Peng Chen Guorui Ren Jizhen Liu Fang Fang Zhe Chen State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power UniversityBeijing 102206China School of Control and Computer Engineering North China Electric Power UniversityBeijing 102206China Department of Energy Technology Aalborg University9220 AalborgDenmark

Hybrid energy storage system(HESS)is an effective way to mitigate wind power fluctuations on multi-time scale,and can improve influence of large-scale grid-connected wind power on stability and reliability of power system.A novel methodology named zero-phase controlled auto-regressive integrated moving-average(CARIMA)filter is proposed to integrate HESS to smooth wind power ***,a design method for zero-phase CARIMA filter is provided,and then used to determine grid-connected power for a wind storage system and size *** reasons,direct current(DC)component caused by energy storage efficiency and grid-connected power delay caused by phase shift,for causing superfluous energy storage configuration are *** addition,a nonlinear programming scheduling strategy considering battery degradation is *** imbalance caused by efficiency difference during dynamic adjustment of energy storage output power is ***,thermostatically controlled loads(TCLs)are integrated in sizing and scheduling HESS to reduce energy storage demand and improve operating conditions of energy ***,effectiveness of the proposed strategy is verified by a case study.

关键词： CARIMA demand response energy storage optimization wind power zero-phase

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Electromagnetic Transient Modeling and Real-time simulation Based on state-space Equations 4

Electromagnetic Transient Modeling and Real-time Simulation ...

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4th International Conference on New Energy and power Engineering, ICNEPE 2024

作者： Guo, Tianyu Hu, Binjiang Luo, Hui Tu, Liang Zhao, Yanjun Hu, YuFeng China Southern Power Grid State Key Laboratory of Hvdc Electric Power Research Institute Guangdong China Guangdong Provincial Key Laboratory of Intelligent Operation and Control for New Energy Power System Guangdong China China Southern Power Grid Csg Key Laboratory for Power System Simulation Electric Power Research Institute Guangdong China China Southern Power Grid Co. Ltd China

ISBN: (纸本)9798331516086

Due to the different output characteristics of different components of the power system, the simulation results of its output deviate from the actual situation. Therefore, the electromagnetic transient modeling and real-time simulation based on the state space equation are proposed. From the perspective of rectifier, DC transmission line, inverter and control system, the composition of the state space model of the complete power system and the output characteristics of each part in the operation process are analyzed. In the test results, the design method can achieve a stable fit between the real-time simulation results of voltage waveform containing two VSC modules and the actual situation. © 2024 IEEE.

关键词： Electromagnetic transients

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Fault Location Detection of Transmission Lines in Noise Environments Based on Random Matrix Theory

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CSEE Journal of power and Energy systems 2022年第4期8卷 1233-1241页

作者： Jun An Zihan Deng Haipeng Chen Gang Mu Key Laboratory of Modern Power System Simulation and Control&Renewable Energy Technology Ministry of Education(Northeast Electric Power University)Jilin 132012.Jilin ProvinceChina

Fault detection and location are critically significant applications of a supervisory control system in a smart *** methods,based on random matrix theory(RMT),have been practiced using measurements to detect short circuit faults occurring on transmission ***,the diagnostic accuracy is infuenced by the noise signal in the *** relationship between mean eigenvalue of a random matrix and noise is detected in this paper,and the defects of the Mean Spectral Radius(MSR),as an indicator to detect faults,are theoretically determined,along with a novel indicator of the shifting degree of maximum eigenvalue and its *** comparing the indicator and the threshold,the occurrence of a fault can be ***,an augmented matrix is constructed to locate the fault *** proposed method can effectively achieve fault detection via the RMT without any influence of noise,and also does not depend on system *** experiment results are based on the IEEE 39-bus ***,actual provincial grid data is applied to validate the effectiveness of the proposed method.

关键词： Fault detection maximum eigenvalue noise random matrix theory smart grid

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Transient Synchronization Stability Analysis of Grid-Following Converter power systems Using Local Network Measurements 9th

Transient Synchronization Stability Analysis of Grid-Followi...

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9th Purple Mountain Form on Smart Grid Protection and control, PMF 2024

作者： Wei, Xiaoqiang Liu, Naiyuan He, Zhifeng Yang, Hao Sun, Zhenglong State Grid Heilongjiang Electric Power Company Limited Harbin150000 China Key Laboratory of Modern Power System Simulation and Control & Renewable Energy Technology Ministry of Education Northeast Electric Power University Jilin132000 China

ISBN: (纸本)9789819616701

There is an urgent need to address the transient synchronization stability (TSS) problem caused by the increasing penetration of renewable resources into the power network through grid-following converters (GFL-VSCs). It is challenging to analyze the TSS in power systems with high penetration of renewable resources due to the complex interaction between a large number of GFL-VSCs and power network. Although some research has been carried out on TSS assessment of GFL-VSC systems, its application is limited because measuring the numerous internal parameters of distributed converters is hard. To fill this gap, this paper proposes a TSS analysis method using local network measurements. The present study first constructs a port energy function for PLL-controlled converters, establishing the relationship between the internal control and the transient energy of the converter. Secondly, the branch energy function is constructed using the law of energy conservation. Due to transient energy interactions between the converters and the branches, the transient instability characteristics of the converters are mapped into the network. Transient instability characteristics are extracted through PMUs in the network. On this basis, the TSS of the GFL-VSC systems is analyzed through the identified critical branches. Finally, the effectiveness of the proposed method is validated through simulations on the modified IEEE 39-BUS system and a practical power system. © state Grid Electric power 2025.

关键词： Transient stability

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simulation Analysis of EFDC of Oil-Paper Insulation under Typical Electrode Structures with the Influence of Harmonic Voltage 9

Simulation Analysis of EFDC of Oil-Paper Insulation under Ty...

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9th Asia Conference on power and Electrical Engineering, ACPEE 2024

作者： Zhang, Ning Hao, Jian Xu, Jing Wang, Jixiang Chen, Houhe Liao, Ruijin Northeast Electric Power University Key Laboratory of Modern Power System Simulation and Control & Renewable Energy Technology Ministry of Education Jilin China Chongqing University State Key Laboratory of Power Transmission Equipment Technology School of Electrical Engineering Chongqing China

ISBN: (纸本)9798350309638

The primary sources of harmonic distortion in the new power system are a high percentage of access to power electronic equipment and a high percentage of renewable energy grid connections. These factors pose a major risk to the UHV converter transformer oil-paper insulation performance. However, the influence law of harmonic voltage on the electric field distribution characteristics (EFDC) of oil-paper insulation is still unclear;thus, the law of variation of spatial maximum electric field strength (SMEFS) under the action of harmonic voltage and the EFDC on the surface of oil-immersed insulating paper are investigated in this paper by building a two-dimensional simulation model of the electric field distribution of oil-paper insulation under ball-plate and cylinder-plate electrode structure. The results indicate that the two electrode structures' SMEFS are situated in the narrow oil gap between the oil-impregnated insulating paper and the high-voltage electrode;under the influence of the same harmonic components, the insulating paper's surface exhibits an inverse power function decay in the electric field distribution, with the cylinder-plate electrode decaying more quickly than the ball-plate electrode. Meanwhile, for both electrode structures, with the increase of the 5th and 13th harmonics, the SMEFS and the insulating paper surface field strength both increase linearly and are higher than that of the power frequency field strength, while for the 7th and 11th harmonics, the ball-plate electrode weakens the electric field and then increases it with the increase of the harmonic content, whereas the cylinder-plate electrode only increases the electric field. © 2024 IEEE.

关键词： Electric fields

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