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SSRN 2023年

作者： Liu, Xingmou Gu, Yan Li, Lei Yang, Yongming Cheng, Peng Jadoon, Ammad Chongqing Key Laboratory of Complex Systems and Bionic Control Chongqing University of Posts and Telecommunications Chongqing400065 China State Key Laboratory of Power Transmission Equipment & System Security and New Technology School of Electrical Engineering Chongqing University Chongqing400044 China State Grid Sichuan Electric Power Company Chengdu Power Supply Company Chengdu610000 China NFC-Institute of Engineering &Technology Multan Pakistan

Thermal and insulation performance of the High Voltage Cable Terminal (HVCT) could effectively improve the reliability and economy of power energy transmission. In this paper, a numerical model of the electromagnetic heat flow field was proposed to analyze the heat transfer and temperature characteristics of HVCT under oil leakage defects. This model was the first validated using operation data from the actual equipment and the relative error was less than 1.51%. The effects of oil leakage fault on the global and local temperature distribution of the HVCT were then investigated under different load currents. In addition, the local temperature rise effect of different ambient temperatures on the HVCT oil leakage defect was also considered. Finally, combined with reference indicators such as oil level, temperature, and temperature gradient, a qualitative and quantitative evaluation of the oil leakage fault of HVCT was performed. The results showed that the temperature of the core, surface, and their maximum temperature gradient were linearly related to the ambient temperature. However, the temperature of the core at the oil leak exceeded the normal temperature by up to 7.2 °C with 1000A load current, and the temperature gradient change reaches 681.3 °C/m, which indicated that the convection heat dissipation effect of the oil-deficient part was poor, and the heat accumulates near the cable core. Therefore, the numerical model and analytical results presented in this paper provided an important method for online temperature monitoring and fault analysis of HVCTs. © 2023, The Authors. All rights reserved.

关键词： Thermal gradients

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Improved Deep Belief Network and Model Interpretation Method for power system Transient Stability Assessment

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Journal of Modern power systems and Clean Energy 2020年第1期8卷 27-37页

作者： Shuang Wu Le Zheng Wei Hu Rui Yu Baisi Liu State Key Laboratory of Power System Department of Electrical EngineeringTsinghua UniversityBeijing 100084China Stanford University StanfordCalifornia 94305USA Southwest Branch State Grid Corporation of ChinaChengdu 610041China

The real-time transient stability assessment(TSA)and emergency control are effective measures to suppress accident expansion,prevent system instability,and avoid large-scale power outages in the event of power system ***,real-time assessment is extremely demanding on computing speed,and the traditional method is not *** this paper,an improved deep belief network(DBN)is proposed for the fast assessment of transient stability,which considers the structural characteristics of power system in the construction of loss *** learning has been effective in many fields,but usually is considered as a black-box *** the perspective of machine learning interpretation,this paper proposes a local linear interpreter(LLI)model,and tries to give a reasonable interpretation of the relationship between the system features and the assessment result,and illustrates the conversion process from the input feature space to the high-dimension representation *** proposed method is tested on an IEEE new England test system and demonstrated on a regional power system in *** result demonstrates that the proposed method has rapidity,high accuracy and good interpretability in transient stability assessment.

关键词： Transient stability assessment(TSA) representation learning deep belief network(DBN) local linear interpretation(LLI) visualization emergency control

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Multi-agent-based Rolling Optimization Method for Restoration Scheduling of Distribution systems with Distributed Generation

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Journal of Modern power systems and Clean Energy 2020年第4期8卷 737-749页

作者： Donghan Feng Fan Wu Yun Zhou Usama Rahman Xiaojin Zhao Chen Fang IEEE Key Laboratory of Control of Power Transmission and Conversion of the Ministry of Education Department of Electrical EngineeringShanghai Jiao Tong UniversityShanghaiChina Electric Power Research Institute State Grid Shanghai Municipal Electric Power CompanyShanghaiChina

Resilience against major disasters is the most essential characteristic of future electrical distribution systems(EDSs).A multi-agent-based rolling optimization method for EDS restoration scheduling is proposed in this *** a blackout occurs,considering the risk of losing the centralized authority due to the failure of the common core communication network,the available agents after disasters or cyber-attacks identify the communication-connected parts(CCPs)in the EDS with distributed communication.A multi-time interval optimization model is formulated and solved by the agents for the restoration scheduling of a CCP.A rolling optimization process for the entire EDS restoration is *** the scheduling/rescheduling in the rolling process,CCPs in EDS are re-identified and the restoration schedules for CCPs are *** decentralized decision-making and rolling optimization,EDS restoration scheduling can automatically start and periodically update itself,providing an effective solution for EDS restoration scheduling in a blackout event.A modified IEEE123-bus EDS is utilized to demonstrate the effectiveness of the proposed method.

关键词： electrical distribution system restoration scheduling multi-agent system rolling optimization

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Improving Surface Performance of Composite Insulators by Multifunctional Nano-Coating

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SSRN 2022年

作者： Liu, Shuming Liu, Shuqi Wang, Qian Zuo, Zhou Liang, Xidong Chen, Zhong State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing100084 China School of Material Science and Engineering Nanyang Technological University 639798 Singapore

Insulator is an important component of outdoor insulation systems. It works in complex environments and faces a series of problems such as surface contamination, loss of hydrophobicity, accumulation of surface charges, which may eventually lead to flashover. Aiming to solve these problems in a simple and scalable method, we propose a multifunctional nano-coating based on SiO 2 /PDMS/EP. By the combination of multiscale structure and low surface energy modification, this coating shows excellent water-repellency performance, a large contact angle greater than 160° and a small rolling angle near 0° are achieved on coated silicone rubber, which enables the surface with excellent self-cleaning performance. Benefiting from the multiscale roughness, the heat transfer is inhibited by the reduced contact area, which further slows down the icing process on coated silicone rubber. The de-icing force on coated silicone rubber is also smaller than that on pristine silicone rubber. This coating also introduces many shallow traps to the surface, which is beneficial to the fast surface charge dissipation in a short time. Besides, the high water-repelling ability can promote the droplet to roll away under the action of electrical field force, which alleviates the electrical distortion caused by the droplets. As a result, the wet flashover voltage of coated silicone rubber is 60% higher than that of pristine silicone rubber. This multifunctional coating is a facile, scalable, and effective approach to improving the comprehensive surface performance of insulators. © 2022, The Authors. All rights reserved.

关键词： Flashover

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An Automatic Ridge Estimation Method for Tacholess Order Tracking of Wind Turbine Gearbox Under Varying-Speed operation

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SSRN 2023年

作者： Liu, Changliang Liu, Shaokang Wu, Yingjie Liu, Weiliang Liu, Shuai Control and Computer Engineering Department University of North China Electric Power Beijing102200 China Baoding key Laboratory of State Detection and Optimization Regulation for Integrated Energy System Baoding071000 China Automation Engineering Department University of Northeast Electric Power Jinlin132000 China

The instantaneous shaft speed estimation method of wind turbine gearbox based on time-frequency ridge estimation is the most widely used method, but it requires parameter adjustment and expert knowledge to ensure the accuracy of ridge estimation, which significantly reduces the effectiveness of such methods in practice. In this paper, an end-to-end automated ridge estimating (ARE) method is proposed. ARE uses the inherent harmonic relationship in the vibration signal of wind turbine (WT) gearbox to construct a selection index for automatically selecting the target ridge with clear physical meaning. Then, a sub-region division strategy is proposed to avoid the interference of other components and improve computational efficiency. Finally, a parameter-free objective function considering both the amplitude and smoothness of the ridge is proposed to achieve target ridge estimation. The vibration signals of different WT gearboxes collected on-site were applied to verify the performance of ARE. The result shows that ARE realizes the automatic estimation of a ridge. It outperforms other methods in terms of accuracy and computational efficiency. © 2023, The Authors. All rights reserved.

关键词： Computational efficiency

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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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Analysis of a hybrid system combining solar-assisted methanol reforming and fuel cell power generation

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Energy Conversion and Management 2023年 297卷

作者： Zhao, Ke Kong, Hui Tan, Sicong Yang, Xiao-Guang Zheng, Hongfei Yang, Tao Wang, Hongsheng School of Mechanical Engineering Beijing Institute of Technology Beijing100081 China State Key Laboratory of Power System Operation and Control Department of Thermal Engineering Tsinghua-BP Clean Energy Center Tsinghua University Beijing100084 China Shenzhen Automotive Research Institute Beijing Institute of Technology Guangdong Shenzhen518118 China & Department of Materials Science and Engineering City University of Hong Kong Hong Kong SAR Kowloon China

The proton exchange membrane fuel cell (PEMFC) is an efficient and clean power unit that has become a research hotspot for scholars around the world, but the hydrothermal management of the PEMFC limits the cell performance and hinders its large-scale application. In the paper, a hybrid system combining solar-assisted reforming of methanol and fuel cell power generation is proposed, in which methanol is used as a coolant in the hydrothermal management of the PEMFC subsystem to take away the waste heat, and further reformed for hydrogen production with the assistance of the solar energy subsystem to improve the hybrid system efficiency. The study is carried out at both the single cell level and system level to investigate the effect of solar energy on the performance of the hybrid system by simulation results, which are obtained from the finite element software, such as the performance of the PEMFC. The results show that the novel hydrothermal management method using methanol and water in the single cell can control the temperature at 60–80 °C. The highest power density of the single cell reaches 0.595 W/cm2 at a water-to-alcohol ratio of 1:1 and a coolant flow rate of 2.846 mol/s. In addition, the exergy of this hybrid system improves by 76.36% compared to the exergy of the solar thermochemical methanol reforming system at a reaction temperature of 200 °C when the methanol reforming reaction is more complete. The system efficiency can reach up to 59.15%, compared to the solar thermochemical methanol reforming system and the methanol reforming system heated by combustion of methanol, which can only reach 51.10% and 43.18%, respectively. This study provides a novel method for addressing the hydrothermal management issue of PEMFC and a new idea for the efficient utilization of solar energy. © 2023 Elsevier Ltd

关键词： Solar energy

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Design and Implementation of a Cascade Vertical Pulling Artificial Intelligent Automatic Yarn Dropping Robot 5

Design and Implementation of a Cascade Vertical Pulling Arti...

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5th International Conference on Automation, control and Robotics engineering, CACRE 2020

作者： Yu, Qingguang Liu, Yuming Jiang, Zhicheng Long, Gaoxiang Tsinghua University State Key Laboratory of Power System Department of Electrical Engineering Beijing China

ISBN: (纸本)9781728198880

As of improving the automation level and the labor efficiency, yarn dropping robot takes an important role in the ring spinning textile machine. Design and implementation of a cascade vertical pulling artificial intelligent automatic yarn dropping robot in this paper. After researching of the yarn dropping process of ring spinning machines, the kinematics and dynamics analysis of the yarn dropping robot are put forward. The cascade vertical pulling strategy and the 3D circular arc interpolation algorithm and flying scissors algorithm of a 5-axis PAC control servo system is designed and implemented. The results of experiments and operating in the sites for years show high performance of the cascade vertical pulling artificial intelligent automatic yarn dropping robot for ring spinning. © 2020 IEEE.

关键词： Yarn

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Research on Energy Consumption and Environmental Parameters Evaluation of Nearly Zero Energy Building Based on LoRa IOT 4

Research on Energy Consumption and Environmental Parameters ...

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4th International Conference on Sensing, Diagnostics, Prognostics, and control, SDPC 2020

作者： Yu, Qingguang Liu, Yuming Jiang, Zhicheng Long, Gaoxiang Tsinghua University State Key Laboratory of Power System Department of Electrical Engineering Beijing China

ISBN: (纸本)9781728170503

With the development of the Internet of Things (IOT) technology, people have higher requirements for quality of life, and they have put forward higher requirements for visualization and intelligence for various environmental indicators of the house. This paper designs a LoRa IoT system based on embedded web for nearly zero energy buildings. The hardware and software of the system's IoT structure are designed to achieve online monitoring of energy consumption and environment. The comprehensive research proposes calculation methods for parameters such as environmental comfort, environmental health, and productivity. These indicators are more decentralized, and this paper sorts out these complicated parameters and unifies the concise indicators. The innovative work is that the environmental comfort is evaluated from the perspective of thermal comfort and air quality, the influence of acoustical intensity is added to the environmental health, and the influence of light is added to the productivity. Finally, the proposed algorithm is connected to the actual project and applied to several nearly zero energy buildings. © 2020 IEEE.

关键词： Health

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Research on primary frequency regulation of grid integrated concentrating solar power plant 9

Research on primary frequency regulation of grid integrated ...

引用

9th China International Conference on Electricity Distribution, CICED 2021

作者： Qian, Minhui Zhao, Dawei Zhao, Liang Zhu, Lingzhi Wu, Fubao Chen, Ning Qin, Wenping Xu, Chang Jiangsu Eng. Technol. Res. Ctr. for Ener. Storage Conversion and Applic. China Elec. Pwr. Res. Inst. State Key Laboratory of Operation and Control of Renewable Energy and Storage Systems Nanjing China Shanxi Key Lab of Power System Operation and Control Taiyuan University of Technology Taiyuan China College of Energy and Electrical Engineering Hohai University Nanjing China

ISBN: (纸本)9781728192291

High share of renewable energy will be one of the basic features of power systems in the future around the world. Compared with photovoltaic (PV) and wind power, concentrating solar power (CSP) equipped with heat storage system has similar regulation characteristics with thermal power units, and it can effectively overcome the intermittent and volatility of PV and wind power generation. Meanwhile, the CSP units can strongly support the voltage, frequency and short-circuit capacity of power systems. So, CSP is a very promising power generation technology for the future power system. The CSP unit has better ramp ability than thermal power unit, and can generally reach a speed between 2% and 5% of rated power per minute. stated thus, the CSP unit has a good potential to participate in the primary frequency regulation of power grid. At present, there are many researches on the performance of each subsystem of the CSP unit in worldwide, and there are also some theoretical researches on the participation of CSP unit in the dispatching operation of power system. However, there is a lack of research reports on CSP plant's participation in the primary frequency regulation of the power grid, which is an urgently needed feature for the future power systems with high share of renewable energy. In this paper, a model with primary frequency regulation ability of CSP unit is established in DIgSILENT powerFactory software. A revised two-area four-machine system is used to investigate the CSP unit's participation in primary frequency regulation of power system. The simulation results show the good frequency regulation performance of CSP unit, which can effectively support the stable operation of power system with high share of renewable energy in the future. © 2021 IEEE.

关键词： Concentrated solar power

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