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2021 Annual Meeting of CSEE Study Committee of HVDC and power Electronics, HVDC 2021

作者： Wei, Xiao Shuwen, Miao Jun, Jia Qiao, Zhu Yong, Huang Power System and Large-scale Power Generation Equipment Safety Control and Simulation Laboratory Tsinghua University Beijing100084 China Southwest Jiaotong University Chengdu610031 China Tsinghua Sichuan Energy Internet Research Institute Chengdu610041 China Sichuan Homwee Technology Co.Ltd. Chengdu610041 China

ISBN: (纸本)9781839537035

Since lithium-ion batteries are the core components and main sources of failures in electric vehicles and energy storage systems, fault diagnosis plays a crucial role in the stable operation of lithium-ion batteries. In this paper, a multidimensional indicator-based lithium-ion battery fault diagnosis algorithm is proposed to obtain the weights of different dimensional indicators in the battery fault evaluation system, which applies entropy weight method to calculate the risk coefficients of each individual battery for battery fault diagnosis. The algorithm validation work in this paper is completed in the MIT-Stanford public experimental data set and the actual operation data set of the energy storage system. Firstly, the data feature extraction method suitable for engineering application scenarios is selected. Then, the entropy weight method is used to calculate the weights of each indicator, and then the cause of the battery failure is analysed based on the weight information of each indicator. The method with the entropy of each dimensional indicator to calculate its weight can locate the faulty battery and reduce the subjectivity in the fault analysis process. Meanwhile, the method is suitable for real-time fault diagnosis of lithiumion battery systems without complicated training models and hyper-parameter adjustment processes. © 2021 IET Conference Proceedings. All rights reserved.

关键词： Failure analysis

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Development and prospect of direct‐current circuit breaker in China

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High Voltage 2021年第1期6卷 1-15页

作者： Weijiang Chen Rong Zeng Junjia He Yi Wu Xiaoguang Wei Taixun Fang Zhanqing Yu Zhao Yuan Yifei Wu Wandi Zhou Bing Yang Lu Qu STATE GRID Corporation of China BeijingChina Department of Electrical Engineering Key Laboratory of Control and Simulation of Power System and Generation EquipmentTsinghua UniversityBeijingChina School of Electric and Electronic Engineering Huazhong University of Science&TechnologyWuhanChina School of Electrical Engineering Xi'an Jiaotong UniversityXi'anChina Global Energy Interconnection Research Institute Co. LtdBeijingChina NR Electric Co. LtdNanjingChina

The direct‐current circuit breaker(DCCB)is the most ideal choice for DC fault isolation in DC *** a late start,China's research and development on the DCCB have made outstanding *** article provides a brief glance of current China's DCCB development *** begins by sorting out the technical route according to the topology of *** it systematically summarises both mechanical and hybrid DCCBs with focussing on the aspects of topology structure and principle,key technology and characteristics,prototype development and *** is apparent that Chinese scientists and engineers confronted the worldwide problem of large capacity DC breaking,and put forward a comprehensive solution which consists of an innovative topology structure based on coupled negative voltage circuit,breaking throughs on the key technologies such as highly controllable and reliable fault current commutation,millisecond‐level ultra‐fast and efficient electromagnetic repulsion mechanism,high tolerance and high stability power electronic switch,low residual voltage and fast response energy consumption device,*** article states that the world's first set of hybrid high‐voltage(HV)DCCB,and the first set of mechanical HV DCCB have been *** DCCBs will soon be deployed to the DC grids which have the highest voltage levels therefore require the strongest breaking *** achievements are leading the world in the development and application of *** article also discusses the overall development trends of DCCB in the areas of new topologies,key techno-logical breakthroughs and application scenarios,*** discussions serve as references for DCCB's future technological advancement and its ever‐expanding applications.

关键词： breaking breakthrough discussions

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Big data service capability of enterprise-scale data middle platform

Big data service capability of enterprise-scale data middle ...

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Tsinghua University-IET Electrical Engineering Academic Forum: Constructing Green and Sustainable Energy system 2021

作者： Chen, Lianfu Wang, Xuan Peng, Fang Liu, Shi State Key Laboratory of Control and Simulation of Power System and Generation Equipments Tsinghua University Beijing China Department of Electrical Engineering Tsinghua University Beijing China Big Data Center of State Grid Corporation of China Beijing China

ISBN: (纸本)9781839536199

With the rapid development of technologies such as big data, cloud computing, Internet of things and artificial intelligence, electric power enterprises are faced with the strategic deployment of digital transformation. By upgrading IT architecture, power grid companies build the data middle platform, and separate the data operation and product technology from its front platform. Through service reusing and data sharing, the business capability can be shared, which providing technical support for power enterprises to serve a variety of complex business scenarios. This paper focuses on the architecture design of data middle platform in power grid companies, and analyzes its service capability. In addition, this paper sorts out the capability output framework of big data middle platform, and analyzes the data service requirements and application modellings for data middle platform in different business scenarios. © 2021 Institution of Engineering and Technology. All rights reserved.

关键词： Big data

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A strategy for avoiding overload of AC line after blocking dc line in AC/DC hybrid grid 15

A strategy for avoiding overload of AC line after blocking d...

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15th International Conference on Developments in power system Protection, DPSP 2020

作者： Wang, Hao Kang, Xiaoning Dong, Xinzhou Shaanxi Key Laboratory of Smart Grid Xi'an Jiaotong University Xi'an China State Key Laboratory of Control and Simulation Power System and Generation Equipment Tsinghua University Beijing China

ISBN: (纸本)9781713827894

The development of DC transmission technique is prompting the development of AC/DC hybrid grid. As a new form of the grid, AC/DC hybrid grid faces many challenges one of which is the effect of DC blocking on AC lines. This paper analyses the influence of DC blocking on AC lines. Based on the analysis, a control strategy using wide area information is proposed to avoid the severe overload of AC line after blocking a DC line. The proposed strategy increases the transmission power of normally operating DC line aiming to afford part or all of the transmission task of the blocked DC line. The test result obtained from simulation indicates that the proposed strategy can reduce the overload of AC line after blocking a DC line. © 2020 IET Conference Publications.

关键词： Transmissions

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Space Charge Transport of $\boldsymbol{\text{Al}_2 \mathrm{O}_3}$ /Silicone Rubber Composites Under Thermal Aging

Space Charge Transport of $\boldsymbol{\text{Al}_2 \mathrm{O...

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International Conference on High Voltage Engineering and Application, ICHVE

作者： Yunxiao Zhang Chenning Yan Kai Wu Yuanxiang Zhou Tianfeng Zhang College of Electrical Engineering and Automation Fuzhou University Fuzhou Fujian China Department of Electrical Engineering 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 Electric Power Research Institute Anhui Electric Power Company of State Grid Hefei China

ISBN: (数字)9781665407502

ISBN: (纸本)9781665407519

Silicone rubber (SIR) has been widely used in the insulation of cable accessories due to its excellent performance. In this paper, pure SIR and nano $\boldsymbol{\text{Al}_2 \mathrm{O}_3 / \text{SIR}}$ composites are thermally aged for 0–80 days at $\boldsymbol{200^{\circ} \mathrm{C}}$ . The effects of long-term thermal aging on the space charge transport are analyzed. The results show that with the increase of thermal aging time, the accumulation of heteropolar charge of pure SIR and nano $\boldsymbol{\text{Al}_{2}\mathrm{O}_{3}/\text{SIR}}$ composites gradually decreases and changes to the accumulation of homopolar charge. Compared with pure SIR, the space charge accumulation of $\boldsymbol{\text{Al}_{2}\mathrm{O}_{3}/\text{SIR}}$ composites decreases significantly and changes little with the increase of thermal aging time. It is believed that when doped nano $\boldsymbol{\text{Al}_{2}\mathrm{O}_{3}}$ in SIR, the increase of carrier mobility and the introduction of metal oxides reacting with fallen free radicals to form stable compounds both lead to less space charge accumulation of $\boldsymbol{\text{Al}_{2}\mathrm{O}_{3}/\text{SIR}}$ composites.

关键词： Nanocomposites Impurities Metals High-voltage techniques Aging Space charge Thermal analysis

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

arXiv

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arXiv 2023年

作者： Qu, Jiaqi Wei, Lu Sun, Qiang Zareipour, Hamidreza Qian, Zheng School of Instrumentation and Optoelectronic Engineering Beihang University Beijing China School of Electronics and Information 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 The Department of Electrical and Computer Engineering University of Calgary Calgary Canada

Various faults can occur during the operation of PV arrays, and both the dust-affected operating conditions and various diode configurations make the faults more complicated. However, current methods for fault diagnosis based on I-V characteristic curves only utilize partial feature information and often rely on calibrating the field characteristic curves to standard test conditions (STC). It is difficult to apply it in practice and to accurately identify multiple complex faults with similarities in different blocking diodes configurations of PV arrays under the influence of dust. Therefore, a novel fault diagnosis method for PV arrays considering dust impact is proposed. In the preprocessing 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 the transformed graphical feature matrices. Then, in the fault diagnosis stage, the model of convolutional neural network (CNN) with convolutional block attention modules (CBAM) is designed to extract fault differentiation information from the transformed graphical matrices containing full feature information and to classify faults. And different graphical feature transformation methods are compared through simulation cases, and different CNN-based classification methods are also analyzed. The results indicate that the developed method for PV arrays with different blocking diodes configurations under various operating conditions has high fault diagnosis accuracy and reliability. Copyright © 2023, The Authors. All rights reserved.

关键词： Failure analysis

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Distribution system fault location method using reclosure-generating traveling waves

Distribution system fault location method using reclosure-ge...

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2020 IEEE power and Energy Society General Meeting, PESGM 2020

作者： Dong, Xinzhou Wang, Haozong Xin, Zeyu Shi, Shenxing Wang, Bin Tsinghua University State Key Lab. of Control and Simulation of Power System and Generation Equipment Dept. of Electrical Engineering Beijing China

ISBN: (纸本)9781728155081

Fault location in distribution systems includes 2 subtasks: fault distance estimation and fault section identification. This paper presents a fault location method based on reclosure-generating traveling waves and system topology. Firstly, the reclosure-generating traveling waves under normal and fault conditions are analyzed to find the traveling wave reflected by fault point, through which the fault distance could be estimated. Secondly, we propose a fault section identification method by comparing real measured traveling waves with simulated traveling waves with different potential fault points. Noticing that only time information of traveling waves rather than their magnitude is necessary, instead of using electromagnetic transient simulation, we also present a simplified simulation algorithm that only focuses on the arrival time of traveling waves based on priority queue. Experiments demonstrate that the proposed method can locate fault points in high accuracy with low computational burden. © 2020 IEEE.

关键词： Location

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Numerical simulation of surface discharge in oil paper insulation based on finite element method and cellular automata

Numerical simulation of surface discharge in oil paper insul...

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22nd International Symposium on High Voltage Engineering (ISH 2021)

作者： J. Chen Y. Zhou Y. Zhang X. Huang L. Zhang State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing People's Republic of China

Surface discharge of oil paper insulation is one of the insulation defects in converter transformers. However, the mechanism of surface discharge in oil paper insulation remains unclear. A novel method of surface discharge in oil paper insulation based on finite element method (FEM) and cellular automata (CA) was proposed to study the mechanism and fractal characteristics. Firstly, the needle-plate electrode without normal component of electric field density was adopted as the geometric model, on which the unstructured triangular mesh generation was performed. Then, the FEM is applied to compute the distribution of potential, electric field and charge in the simulated field, which performed better than finite difference method (FDM) in accuracy and complexity of computation. Finally, the CA model was adopted to simulate the development of surface discharge with the electric field threshold. The results indicated that the numerical simulation model based on FEM-CA can simulate the dynamic process and fractal characteristics of surface discharge in oil paper insulation. According to the fractal dimension curve, the surface discharge can be obviously divided into three stages: inception, propagation and flashover. With the increase of applied voltage, the fractal dimension of surface discharge increases in inception stage, then decreases in propagation stage, and finally increases in flashover stage.

关键词： cellular automata electric fields electrodes finite difference methods finite element analysis flashover fractals mesh generation power transformer insulation surface discharges transformer oil

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Influences of temperature on Space Charge in Gas-to-Liquid Oil-Impregnated Paper 7

Influences of temperature on Space Charge in Gas-to-Liquid O...

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7th IEEE International Conference on High Voltage Engineering and Application, ICHVE 2020

作者： Zhou, Yuanxiang Huang, Xin Zhang, Ling Zhang, Yunxiao Zhou, Zhongliu Teng, Chenyuan China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Department of Electrical Engineering Beijing China

ISBN: (纸本)9781728155111

Gas-to-liquid (GTL) transformer oil has been on trial in converter transformers. However, its influence on the space charge characteristic is not clear. This work aims at exploring space charge characteristics of GTL oil at different temperatures as well as comparing with commercial naphthenic oil (KI50X). Space charge distribution during the polarization and the dissipation process in the GTL oil-impregnated paper at different temperature was measured by the pulse electroacoustic method (PEA), which were contrasted with those of the KI50X oil-impregnated paper. Results illustrated that high temperature accelerated the injection and migration of charge carriers in the oil-impregnated paper. And the polarity of the accumulated charge in the vicinity of anode changed from positive to negative with the increase of temperature. It was perceived that oil-paper conductivity and carrier mobility grew with the increase of temperature, resulting in the easier migration of injected charge to another electrode. Furthermore, the space charge dissipation rate in the GTL oil-impregnated paper is lower than that in the naphthenic oil-impregnated paper at the same temperature. Thus, a longer time interval of tests or switch operation in the factory test and operation process may need if GTL oil is used rather than naphthenic oil. © 2020 IEEE.

关键词： Electric space charge

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Research on Low Voltage Ride through and Reactive power Support of Hydrogen Production power Supply

Research on Low Voltage Ride through and Reactive Power Supp...

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Smart power & Internet Energy systems (SPIES), International Conference on

作者： Mingqi Zhang Ruitong Liu Kui Wang Kai Sun Qinglai Guo Yongdong Li Dept. of Electrical Energineering State Key Lab. of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China State Grid Liaoning Electric Power Co. LTD. Electric Power Research Institute Shenyang China

Hydrogen energy, a type of green secondary energy, has attracted much attention in recent years. The production of hydrogen by water electrolysis is less harmful to the environment and makes it possible to obtain hydrogen with a high degree of purity. But it requires a lot of electricity and is expensive. Installed capacity and the share of electricity generation from new energy sources have increased recently. The "double high" trend in the power system is becoming apparent. The combination of new energy power generation and hydrogen production by water electrolysis can not only promote the absorption of new energy power generation, but also reduce the cost of hydrogen production. The conventional thyristor power supply system for hydrogen production has low power factor and poor harmonic performance, which cannot meet the requirements of the new power system. Hydrogen production power supply based on fully controlled devices is gradually becoming mainstream. In this paper, the low voltage ride through capability and the reactive power support function for the power grid of hydrogen production power supply based on fully controlled devices are verified by simulation. For both symmetrical and asymmetrical faults, the hydrogen production power supply can ride through the fault.

关键词： Performance evaluation Reactive power power supplies Hydrogen Production Voltage power grids

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