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Conference on Electrical Insulation and Dielectric Phenomena, (CEIDP)

作者： Yuanxiang Zhou Xin Huang Ling Zhang Yunxiao Zhang Zhongliu Zhou Chenyuan Teng Lei Xue Meng Huang The Wind Solar Storage Division of State Key Laboratory of Power System and Generation Equipment School of Electrical Engineering Xinjiang University Urumqi China China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Haidian Beijing China State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power Universiy Beijing China

ISBN: (纸本)9781728195728;9781728195735

Oil-paper insulation bears AC/DC composite voltage in converter transformers. However, the AC/DC space charge behavior is still not clear, which will result in electric field distortion, material aging and even insulation failure. In this work, the space charge distribution of oil-paper under the AC/DC composite voltage with the AC/DC ratio of 1:1, 1:3, 1:5, and 1:7, is studied by pulse electroacoustic (PEA) method, respectively. It was found that as DC component increases, the accumulated charge near the electrode decreases, while the interior charge increases. It suggests that DC stress mainly influences the amount and the depth of space charge accumulation. AC component has a relatively significant impact on the injection and extraction behavior of space charge near the electrode. Furthermore, AC/DC composite voltage enhances the migration of space charge compared with that under DC voltage. This research contributes to the further understanding of the space charge characteristics of oil-paper under AC/DC composite voltage, which will benefit the safe and stable operation of converter transformers.

关键词： Electrodes Conferences Space charge Oil insulation Aging Distortion Dielectrics

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Fault diagnosis for PV arrays considering dust impact based on transformed graphical features of characteristic curves and convolutional neural network with CBAM modules

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Applied Energy 2024年 355卷

作者： Jiaqi Qu Qiang Sun Zheng Qian Lu Wei Hamidreza Zareipour School of Instrumentation and Optoelectronic Engineering Beihang University Beijing China State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing China School of Electronics and Information Engineering Beihang University Beijing China The Department of Electrical and Computer Engineering University of Calgary Calgary Canada

Various faults can occur during the operation of photovoltaic (PV) arrays, and both dust-affected operating conditions and various diode configurations complicate the faults. However, current methods for fault diagnosis based on I-V characteristic curves usually do not effectively use all the distinguishable information contained in the I-V curves or often rely on calibrating the field characteristic curves to standard test conditions (STC). It is difficult to apply these methods in practice and accurately identify multiple complex faults with similarities in different blocking diode configurations of PV arrays under the influence of dust. Therefore, a novel fault-diagnosis method for PV arrays that considers the impact of dust is proposed. In the pre-processing stage, the Isc-Voc normalized Gramian angular difference field (GADF) method is presented, which normalizes and transforms the resampled PV array characteristic curves from the field, including I-V and P-V, to obtain transformed graphical feature matrices. Subsequently, in the fault diagnosis stage, the convolutional neural network (CNN) model with convolutional block attention modules (CBAM) is designed to classify faults, which identifies complex fault types from the transformed graphical matrices containing complete discriminative fault information. In addition, the performances of different graphical feature transformation and CNN-based classification methods are compared using case studies. The results indicate that the developed method for PV arrays with different blocking diode configurations under various operating conditions has high fault diagnosis accuracy and reliability.

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Contaction of Atoms for Outstanding Dielectric Characteristics in Kx-Passivated Polymer Dielectrics

SSRN

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SSRN 2022年

作者： Li, Xiao-Fen Wang, Tian-Yu Liu, Bai-Xin Liu, Jian-Bo Zhang, Gui-Xin Wang, Zhong Lin School of Materials Science and Engineering Tsinghua University Beijing100084 China State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing100084 China CAS Center for Excellence in Nanoscience Beijing Institute of Nanoenergy and Nanosystems Chinese Academy of Sciences Beijing100083 China School of Nanoscience and Technology University of Chinese Academy of Sciences Beijing100049 China School of Material Science and Engineering Georgia Institute of Technology AtlantaGA30332 United States

High dielectric characteristics polymer dielectrics are crucial for high-power, high-integration, and high-energy storage density electrical devices and film capacitors. However, polymer dielectrics accumulate much charge during operation, causing local electric field distortion and flashover or breakdown. The deep-level defect state (electron/hole accumulation center) is a fundamental factor affecting dielectric strength. Unfortunately, related research, especially on passivating deep-level defects in polymer dielectrics, is minimal. In this paper, based on experiments and first-principles calculations, it is found that KX (X=F, Cl, Br, I) effectively passivates deep-level defect states in polymer dielectrics. Further analysis of the physical passivation mechanism reveals that the deep-level defect cation passivation principle is the cation dipole effect on polymers. The principle of anion passivation of deep-level defects by suspending anions and cations is the key to producing more stable C covalent bonds. This stable covalent bond transfers the local charge from the C with the lone electron pair that originally contains the hanging bond. Therefore, some transfer occurs and the anion implements effective passivation. This paper addresses the design of high-performance polymer dielectrics, providing a reference for experimental and theoretical analyses. © 2022, The Authors. All rights reserved.

关键词： Passivation

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Feasibility Analysis of Single-end Equivalent Modeling to LCC-HVDC Transimission system

Feasibility Analysis of Single-end Equivalent Modeling to LC...

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IEEE Conference on Energy Internet and Energy system Integration (EI2)

作者： Bin Wang Zhizhong Li Qi Guo Zhijiang Liu Shuyong Li Liu Cui Tsinghua University Beijing China Guangdong Provincial Key Laboratory of Intelligent Operation and Control for New Energy Power System State Key Laboratory of HVDC (Electric Power Research Institute China Southern Power Grid) Guangzhou China National Energy Power Grid Technology R&D Centre State Key Laboratory of HVDC (Electric Power Research Institute China Southern Power Grid) Guangzhou China China Southern Power Grid State Key Laboratory of HVDC (Electric Power Research Institute China Southern Power Grid) CSG Key Laboratory for Power System Simulation Electric Power Research Institute Guangzhou China

ISBN: (数字)9781728196060

ISBN: (纸本)9781728196077

The commutation failures seriously threaten the safe operation of hybrid AC/DC grid. Considering that commutation failure occurs only on the inverter side, it is very important to study the voltage controlled current source model of LCC HVDC single terminal measurement information with high equivalent accuracy, which is very important for the practicality of real-time electromagnetic transient simulation of LCC HVDC dynamic phasor model. In order to this problem, this paper further discusses the single terminal equivalent model of LCC HVDC system which does not depend on the measurement information of DC sending end AC system, and explores the estimation method of single terminal fast transient response of complex AC/DC coupling faults induced by AC side fault of LCC HVDC inverter station and participation of DC control separation. The error distribution of single terminal equivalent calculation is quantitatively analyzed to lay a foundation for the follow-up protection and control technology research.

关键词： Analytical models Solid modeling Voltage measurement HVDC transmission Estimation Inverters Voltage control

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power grid frequency regulation participated by photovoltaic generation to adapt to different control modes of grid-side AGC

Power grid frequency regulation participated by photovoltaic...

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8th Renewable power Generation Conference (RPG 2019)

作者： Gangui Yan Wenbo Hu Qi Jia Dan Wang Guoqing Zhou Key Laboratory of Modern Power System Simulation and Control & Renewable Energy Technology Ministry of Education Northeast Electric Power University Jilin 132012 China

ISBN: (数字)9781839531248

ISBN: (纸本)9781839531255

Large-scale grid-connection of photovoltaic (PV) generation causes the power system to face the problem of insufficient inertia and insufficient frequency modulation capability. One of the important means to solve this problem is to take part in grid frequency regulation actively. On the basis of spare certain active power, this paper puts forward the active power-frequency droop control strategy. By modifying the original control structure of the inverter, PV generation actively takes part in the grid frequency primary regulation. In order to achieve non-error adjustment of frequency, this paper further proposes a secondary frequency regulation control strategy that adapts to different grid-side AGC control modes (constant frequency control mode, constant tie line power control mode and tie line power frequency deviation control mode). The effectiveness and feasibility of the control strategies are verified based on the PSCAD/EMTDC simulation platform.

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Ultra-Short-Term Prediction of Wind power Based on Chaos Theory and ABC Optimized RBF Neural Network

Ultra-Short-Term Prediction of Wind Power Based on Chaos The...

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China International Electrical and Energy Conference (CIEEC)

作者： Yang Cui Shi Yan Huiquan Zhang Siyu Huang Key Laboratory of Modern Power System Simulation and Control & Renewable Energy Technology Ministry of Education (Northeast Electric Power University) Ji Lin China

ISBN: (数字)9781728116754

ISBN: (纸本)9781728116761

Wind energy has strong randomness and volatility, which makes the prediction accuracy of wind power low. In an attempt to improve the accuracy and robustness of ultra-short term prediction of wind power, a wind power prediction method in ultra-short term combining chaos theory and artificial bee colony(ABC) algorithm to optimize RBF neural network is studied in this paper. Firstly, based on chaos theory, the historical wind power data with the highest correlation is found, which is used for RBF neural network training after phase space reconstruction. Then, the artificial bee colony algorithm is used to solve the optimal RBF neural network parameters through multiple iterations to construct the optimized neural network model. Finally, considering the uncertainty of the prediction model and data noise, the prediction results are interval, and the robustness of the prediction results is evaluated by calculating the confidence of the corresponding interval. The results of the example show that the method proposed in this paper has good accuracy and robustness.

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A novel frequency regulation control strategy based on the external characteristics of PV generation

A novel frequency regulation control strategy based on the e...

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8th Renewable power Generation Conference (RPG 2019)

作者： Gangui Yan Dan Wang Qi Jia Wenbo Hu Guoqing Zhou Key Laboratory of Modern Power System Simulation and Control & Renewable Energy Technology Ministry of Education Northeast Electric Power University Jilin 132012 China

ISBN: (数字)9781839531248

ISBN: (纸本)9781839531255

Large-scale grid-connected PV generation results in the power system facing with the problem of reduced inertia and inadequate frequency regulation capability, which is urgent for PV generation to take participate in frequency regulation. In this paper, the research object is the double-stage PV generation, a novel frequency regulation control strategy based on the external characteristics of PV generation is proposed. f-U PV compensation is introduced into DC low-voltage control loop, which makes the DC low-voltage vary with the grid frequency, thus controlling the output power of PV generation. The influence mechanism of the control strategy on the frequency dynamic process of power system is also analysed based on the frequency response model (SFR). The results show that: the larger the ΔU PV generated by the f-U PV compensation unit, the more power of PV generation can be generated; the control strategy essentially affects the damping coefficient of the system, which not only affects the transient process of the system frequency, but also the steady-state frequency deviation.

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Evaluation Model for Smart Distribution Network Planning under Energy Interconnection 3

Evaluation Model for Smart Distribution Network Planning und...

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3rd International Symposium on Resource Exploration and Environmental Science, REES 2019

作者： Zhang, Yan Jiang, Zefu Liu, Jinsen Liu, Wenxia Gao, Hua Wang, Yanmin Power Grid Planning Research Center of Guizhou Power Grid Co. Ltd Guiyang Guizhou550003 China State Key Laboratory of Power System and Power Generation Equipment Control and Simulation Department of Electrical Engineering Tsinghua University Haidian Beijing100084 China

Due to the development of the energy interconnection, smart distribution networks (SDNs) should needs be transformed and upgraded to meet new demands. In order to assess the SDN planning, a new index system was conducted from the five attributes. The quantitative methods of all criteria were also defined. An evaluation model was proposed based on AHP weighting and TOPSIS methods. Empirical analysis was performed to verify the feasibility of the evaluation system. © Published under licence by IOP Publishing Ltd.

关键词： Interconnection networks (circuit switching)

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Optimal Capacity Allocation of Integrated Agricultural Energy Network with Enhanced Geothermal system Considering Seasonal Differences

Optimal Capacity Allocation of Integrated Agricultural Energ...

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IEEE Conference on Energy Internet and Energy system Integration (EI2)

作者： Yang Si Laijun Chen Xuelin Zhang Xiaotao Chen Handing Dan Shengwei Mei Qinghai Key Lab of Efficient Utilization of Clean Energy(Tus-Institute for Renewable Energy) Qinghai University Xining China Qinghai Xining Power Generation Branch of Huanghe Hydropower Xining China State Key Laboratory of Control and Simulation of Power System and Power Tsinghua University Beijing China

ISBN: (数字)9781728196060

ISBN: (纸本)9781728196077

As an essential direction of agricultural development in the future, the energy demand for facility agriculture varies significantly in different seasons. In this paper, an integrated energy network structure for independent facility agriculture with combined heat and power enhanced geothermal system (CHP-EGS) is proposed. Based on the CHPEGS cogeneration model and stochastic optimization method, the optimal analysis model for capacity allocation of independent facility agricultural integrated energy network is established. Taking the energy supply of facility agriculture in the hot dry rock resource-rich area of the Gonghe basin in China as an example, the optimal allocation scheme and operation characteristics of integrated energy networks for facility agriculture are analyzed considering the difference of seasonal energy consumption. The results show that, under the same capacity configuration, facility agriculture has sufficient energy support in summer, and its income can be increased by expanding the area of greenhouse or developing product processing. In winter, if the basic energy supply-demand of facility agriculture is to be ensured, the emergency heating system should be configured according to about 30% of the maximum heating demand. The optimization model and case analysis can provide meaningful guidance for seasonal energy sources planning of facility agriculture.

关键词： Analytical models Cogeneration Stochastic processes Agriculture Resource management Thermal energy Energy storage

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The Influence of Positive Temperature Coefficient Material on the DC Electric Field within Epoxy Composites

The Influence of Positive Temperature Coefficient Material o...

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Conference on Electrical Insulation and Dielectric Phenomena, (CEIDP)

作者： Chenyuan Teng Yuanxiang Zhou Ling Zhang Yunxiao Zhang Xuewei Wang Zixia Cheng Meng Huang China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing China The Wind Solar Storage Division of State Key Laboratory of Power System and Generation Equipment School of Electrical Engineering Xinjiang University Urumqi China School of Electrical Engineering Zhengzhou University Zhengzhou China The State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University Beijing China

ISBN: (纸本)9781728195728;9781728195735

Negative temperature (NT) coefficient electrical resistivity of insulating materials causes the distortion of DC electric field, increasing the design and manufacture difficulty of HVDC equipment. The ceramic with positive temperature coefficient (PTC) electrical resistivity was doped into epoxy resin to weaken its temperature dependence of electrical resistivity (0~35 wt%). The electric field and temperature distribution under temperature gradient were simulated. The PTC effect of fillers is able to mitigate the distortion of electric field under temperature gradient, which is through the synergistic optimization of both electrical resistivity-temperature characteristic and thermal conductivity. The optimization of electric field distribution within insulation via BT60/epoxy composites has potential to be used in HVDC electrical equipment.

关键词： Temperature sensors Temperature distribution Temperature dependence Thermal resistance HVDC transmission Conductivity Thermal conductivity

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