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SSRN 2022年

作者： Sun, Guanyue Zhao, Hongfeng Meng, Xiaoji Wang, Feng Dezhou University Shandong254300 China The Wind Solar Storage Division of State Key Laboratory of Control and Simulation of Power System and Generation Equipment School of Electrical Engineering Xinjiang University Urumqi830046 China Xidian Surge Arrester Co. Ltd. Shanxi Xi’an710200 China

This paper studies the aging characteristics of Ca-doped ZnO varistors when the accelerated AC aging chargeability is 0.9 (135°C/ 1000h). Ca-doped ZnO varistors not only there are good breakdown voltage and low leakage current, according to the current-voltage and capacitance-voltage characteristic curves of ZnO varistor before and after aging. After the aging, the breakdown voltage and leakage current change rate are small. The ZnO varistor doped with Ca can slow down the aging speed to a certain extent and has good stability under the AC electric field. © 2022, The Authors. All rights reserved.

关键词： Electric breakdown

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Solving of interval DC power flow using interval Hull algorithm with preconditioning

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Dianli Xitong Zidonghua/Automation of Electric power systems 2014年第3期38卷 130-136页

作者： Ding, Tao Guo, Qinglai Bo, Rui Gu, Wei Sun, Hongbin Zhang, Boming Department of Electrical Engineering Tsinghua University Beijing 100084 China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing 100084 China Midwest Independent Transmission System Operator Inc. Saint Paul 55108 United States School of Electrical Engineering Southeast University Nanjing 210096 China

With intermittent sources integrated into the power grid, power flows of the power grid are getting stochastic. Considering the uncertainty problem of DC power flow in the high voltage transmission system, this paper recommends an interval Hull algorithm with preconditioning to solve the interval DC power flow. Firstly, the diagonal dominant interval coefficient matrix is formed by preconditioning, then the H-matrix is obtained using the interval Hull algorithm. Different approximation methods are employed for the comparison matrix of H-matrix to improve precision. And the upper and lower bound of the distribution of interval DC power flow is obtained with the iterative method. The interval Hull algorithm and Monte Carlo algorithm are compared in the 9-bus test system, the result of which shows that the uncertainty in grid parameters is the main cause of errors. Furthermore, the Hull algorithm with preconditioning, the interval Hull method, the Krawczyk operator iteration method and the Gauss elimination method are compared in terms of accuracy and computing time on an IEEE 57-bus and an IEEE 118-bus test system, respectively. It is shown that the Hull method with preconditioning has the best accuracy, and the time complexity is far lower than that of the Monte Carlo algorithm. © 2014 state Grid Electric power Research Institute Press.

关键词： Iterative methods

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state of the art of hybrid excitation permanent magnet synchronous machines

State of the art of hybrid excitation permanent magnet synch...

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2010 International Conference on Electrical Machines and systems, ICEMS2010

作者： Wang, Shanming Xia, Yonghong Wang, Xiangheng Su, Pengsheng Huang, Shaogang Zhang, Anming State Key Laboratory of Control and Simulation of Power System and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing 100084 China Department of Electrical and Automatic Engineering Nanchang University Nanchang Jiangxi 330031 China Military Deputy Department Dalian 426 Factory No.1 Yanhai Jie Xigang Qu Dalian Liaoning 116005 China

The hybrid excitation permanent magnet machine (HEPMM) combines two kinds of excitation: permanent magnet (PM) and electrical excitation, so it possesses the advantages of PM machines and overcomes the incapability of regulating the excitation field. By now many HEPMM schemes have been presented. In this paper the operation principle, structure, advantages and disadvantages of these HEPMMs have been reviewed and compared in detail. These HEPMMs are classified into three types by new classification method - placement of PM and iron poles. At last novel harmonic excitation HEPMM is proposed and discussed.

关键词： Iron Magnetic fields Windings Stator cores Rotors Stator windings Magnetic circuits

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Physical Passivation of Deep-Level Defect states in Polymer Dielectrics for Outstanding Dielectric Properties

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SSRN 2023年

作者： Li, Xiao-Fen Wang, Tian-Yu Yin, Si-Jia Zhang, Gui-Xin Liu, Jian-Bo Liu, Bai-Xin 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 College of Art and Design Visual Communication Design SuZhou University Suzhou234111 China

The limited dielectric strength of polymer dielectrics hampers their reliable use in highly integrated electrical systems and high-energy storage film capacitors. This constraint is closely associated with the presence of deep-level defect states in polymer dielectrics. Here, we present an efficient and stable approach for the physical passivation of deep-level defect states aimed at enhancing the dielectric properties of polymer dielectrics. Employing inductively coupled plasma technology with argon as the carrier gas, the polymer undergoes substantial decreased deep-level defect states, as evidenced by nano-micro-region defect measurements. Consequently, the localized charge accumulation in the treated polymer dielectric is significantly reduced, resulting in a remarkable 62% increase in flashover voltage. The breakdown strength is also enhanced, and the treated material exhibits long-term stability. Moreover, materials featuring passivated deep-level defect states can boost discharge energy density without compromising efficiency. For instance, PTFE with passivated deep-level defect states maintains a discharge energy density of 1.18 J/cm3 and a charge-discharge efficiency of 95.06% at 200 °C and 300 MV/m. By focusing on deep-level defect states passivation, we introduce a strategy for receiving polymers with exceptional performance and stability. © 2023, The Authors. All rights reserved.

关键词： Passivation

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The Optimal Design of the Second-Order Generalized Integrator Phase-Locked Loop Under power Voltage Distortion Conditions

The Optimal Design of the Second-Order Generalized Integrato...

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

作者： Xin Zhang Lijiao Gong Bin Wang Jindong Si College of Mechanical and Electrical Engineering (Shihezi University) Shihezi China Key Laboratory of Northwest Agricultural Equipment College of Mechanical and Electrical Engineering (Shihezi University) Ministry of Agriculture and Rural Affairs (Shihezi University) Shihezi China State Key Laboratory of Safety Control and Simulation of Power Systems and Power Generation Equipment Tsinghua University Beijing China

ISBN: (纸本)9781665434263

Phase-locked loop (PLL) based on traditional second-order generalized integrator (SOGI) cannot obtain the voltage, frequency and phase information accurately when there are multiple harmonic interference and DC offset in grid voltage. To solve this problem, this paper proposes an improved PLL that can suppress harmonic and eliminate DC component to extract the synchronous signal accurately. First of all, based on the derivation of distorted grid voltage expression, the problem of fluctuation in extracting synchronous signal from three-phase unbalanced voltage with harmonic by traditional PLL is analyzed. Then, the design of improved PLL is proposed, which is composed of an improved second-order generalized integrator and a frequency correction component which can suppress harmonics and eliminate disturbances under the condition of grid voltage distortion, and has self-adaptability in large frequency offset. Determine the control parameters to ensure that the proposed PLL structure has a better rejection to harmonic distortion than previous approaches, and realize accurate tracking of grid fundamental frequency synchronization information. Finally, the behavior of the proposed system is verified with MATlab/Simulink simulation and Hardware-in-Loop Experimental Platform which prove the proposed PLL can realize the synchronous tracking performance of grid frequency and phase quickly and accurately in the non-ideal grid environment, and the results are consistent with the theoretical analysis.

关键词： Analytical models Transient response Voltage Harmonic analysis Harmonic distortion Phase locked loops Frequency synchronization

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Transient interaction of HVAC and HVDC in converter station in HVDC, II: Equivalence circuit in AC side and steady-state debugging

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Gaodianya Jishu/High Voltage Engineering 2011年第3期37卷 537-547页

作者： Chen, Shui-Ming Huang, Lu-Lu Xie, Hai-Bin Yu, Zhan-Qing State Key Laboratory of Control and Simulation of Power System and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing 100084 China

The interaction of nanoseconds, microseconds, milliseconds electromagnetic transients due to AC-DC system operation and fault, the DC converter valve movement, the load generated by changes in the interaction of AC-DC interconnected system electromagnetic transient, can pose a hazard on AC and DC power systems, in particular, lead to the commutation of DC system failures and artesian such serious incidents. Combining theoretical analysis with test, we can establish the analysis method of electromagnetic transient of the full-wave process of the UHV system based on AC-DC interconnected system, control systems, and underground grounding system, and focus on the equivalence circuit of AC side network with the Ward method of equivalency under many operation modes and steady-state debugging for the analysis of AC-DC interconnected system, so as to lay the foundation for the interaction of electromagnetic transient.

关键词： Timing circuits

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Internet Information Applied in the Energy Internet Planning: A Review and Outlook

Internet Information Applied in the Energy Internet Planning...

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IEEE Conference on Energy Internet and Energy system Integration

作者： Lin Cheng Xinchi Ji Fang Zhang Caihao Liang Hailei He State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Tsinghua University China Electric Power Research Institute

ISBN: (纸本)9781538614280

With the development of energy industry and infor-mation technologies, the concept of energy Internet is proposed to prevent the energy crisis and reduce the environmental pollution. However, the planning of energy Internet is facing great challenges that there are large uncertainties of boundary conditions in the planning. The collection of Internet information can help solve the problem. This paper introduces the method of collecting objective data from the Internet, such as renewable energy sources data, climate data, and economic data, and the usage of the data for energy Internet planning. The method of collecting and processing fuzzy information from the Internet are introduced as well. The events related to the energy Internet planning can be perceived and be applied to the multi-scenario planning of energy Internet. Besides, the difficulties and outlooks of the usages are given.

关键词： Energy Internet Internet information Multi-scenario Planning

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Research on Digital Twin Modeling Method for Combustion Process Based on Model Reduction

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SSRN 2024年

作者： Zhang, Yue Li, Jiale Department of Automation North China Electric Power University Hebei Baoding071000 China Hebei Technology Innovation Center of Simulation & Optimized Control for Power Generation North China Electric Power University China Baoding Key Laboratory of State Detection and Optimization Regulation for Integrated Energy System China

In response to the difficulty in obtaining combustion information within coal-fired boiler furnaces, a method is proposed in this study to improve the reduced-order model using clustering segmentation. This approach aims to rapidly predict the combustion temperature field inside the furnace by establishing a twin model of the combustion temperature field. Initially, a finite element method is employed to analyze the combustion system of a 600MW subcritical boiler under various operating conditions. Subsequently, cross-sectional data from burner nozzle positions at each operating condition are extracted. These data are subjected to Proper Orthogonal Decomposition (POD), Spectral Proper Orthogonal Decomposition (SPOD), and Wavelet Transform-POD (WT-POD) for dimensionality reduction to obtain modal data. Comparative analyses are conducted on the modal data obtained from different methods. Furthermore, based on modal data analysis, a Support Vector Machine (SVM) regression model is selected to reconstruct the temperature field. The average absolute error of the reconstructed temperature fields from three methods under different operating conditions is then compared. Finally, the model is refined using clustering segmentation, resulting in an improvement of approximately 0.6% in reconstruction accuracy. This enhancement demonstrates that the clustered POD-SVR-GA model achieves higher accuracy in reconstructing combustion temperature fields after clustering-based improvements. © 2024, The Authors. All rights reserved.

关键词： Support vector machines

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Preventive control for combined heat and power system: A day-ahead security constrained economic dispatch model

Preventive control for combined heat and power system: A day...

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The 11th IET International Conference on Advances in power system control, Operation and Management (APSCOM 2018)

作者： Qunli Lin Xinwei Shen Yinliang Xu Yong Sun Zhenyuan Li Qinglai Guo Hongbin Sun Shenzhen Environmental Science and New Energy Technology Engineering Laboratory Tsinghua-Berkeley Shenzhen Institute Tsinghua University Shenzhen China Jilin Power Grid Company State Grid Corp. of China Jilin China State Key Lab of Control and Simulation of Power System and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing China

ISBN: (数字)9781839530043

Integrated Energy system (IES), which plays a vital role in the development of Energy Internet (EI), can improve the efficiency of energy utilization and integration of renewable energy. However, the coupling between multiple energy systems will bring new challenges to the security control of the IES, such as combined heat and power (CHP) system. For IES, the preventive control is the first line of defense to ensure that the system can keep stable operation when contingencies such as the transmission outage or generator outage happen. This paper proposes a preventive control approach for CHP system, in which a day-ahead security constrained economic dispatch (SCED) model of CHP system considering the coupling of heat and electric is formulated. The model aims to minimize the cost of the whole system, while the preventive control of the system can be achieved with the constraints considering the normal states and contingencies states. Case studies based on the IEEE 9-bus system with CHPs are presented to illustrate the approach. The case result shows that the combined electric and heat optimal dispatch is more economical than when two systems are independently optimized and operated. And the proposed preventive control approach of the CHP system can satisfy both the electric and heat demand, and system security is ensured when the N-1 contingencies happened.

关键词：

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Identification of inactive constraints for SCED model considering uncertain power injection

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Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering 2014年第34期34卷 6050-6057页

作者： Ding, Tao Bo, Rui Guo, Qinglai Sun, Hongbin Huang, Can Li, Fangxing State Key Lab of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing100084 China Midwest ISO St. Paul MN55108 United States Department of Electrical Engineering and Computer Science The University of Tennessee Knoxville TN37996 United States

With the constant expansion of power grid, a large number of security constraints have put tremendous challenges to the online economic dispatch. An efficient tool to eliminate the inactive constraints becomes necessary for security constraints economic dispatch (SCED) in large power systems. In this paper, considering the uncertainty of renewable energy integration, a fast and effective method to identify the inactive security constraints was proposed. Firstly, the definition of uncertain inactive security constraints and a necessary and sufficient condition to identify those were presented respectively. Considering the time-consuming identification, we relaxed the feasible region of original SCED model and utilized greedy algorithm to quickly eliminate part of inactive constraints. Then another necessary and sufficient condition was proposed and verified, where the remaining inactive constraints could be identified. Through the simulation of 24-time periods 9-bus system and 96-time periods IEEE 118-bus system, the speed and effectiveness of proposed method were verified. Moreover, the results can help dispatch operators to locate the transmission lines with the highest congestion risk. © 2014 Chin. Soc. for Elec. Eng.

关键词： Scheduling

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