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2022 IEEE International Conference on High Voltage Engineering and Applications, ICHVE 2022

作者： Zhang, Yunxiao Yan, Chenning Wu, Kai Zhou, Yuanxiang Zhang, Tianfeng College of Electrical Engineering and Automation Fuzhou University Fujian Fuzhou China Tsinghua University State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Beijing China School of Electrical Engineering Xinjiang University The Wind Solar Storage Division State Key Laboratory of Power System and Generation Equipment Urumqi China Electric Power Research Institute Anhui Electric Power Company of State Grid Hefei China

ISBN: (纸本)9781665407502

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 Al2O3/SIR composites are thermally aged for 0-80 days at 200°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 Al2O3/SIR composites gradually decreases and changes to the accumulation of homopolar charge. Compared with pure SIR, the space charge accumulation of Al2O3/SIR composites decreases significantly and changes little with the increase of thermal aging time. It is believed that when doped nano Al2O3 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 Al2O3/SIR composites. © 2022 IEEE.

关键词： Aluminum oxide

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Achieving Nearly 100% Targeted Conversion of NO to NO₂ through Cooperative Activation of Lattice Oxygen and Molecular Oxygen on Dual-Defect LaMnO₃

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Environmental Science and Technology 2025年 2025 May 20页

作者： Qian, Zhen Yuan, Bo Sheng, Shiwei Lai, Fei Chen, Jianjun Mi, Jinxing Ma, Zhao Hao, Runlong Li, Junhua Wang, Lidong Hebei Key Lab of Power Plant Flue Gas Multi-Pollutants Control Department of Environmental Science and Engineering North China Electric Power University Baoding 071003 China State Key Joint Laboratory of Environment Simulation and Pollution Control School of Environment Tsinghua University Beijing 100084 China MOE Key Laboratory of Resources and Environmental Systems Optimization College of Environmental Science and Engineering North China Electric Power University Beijing 102206 China

Inhibiting the deposition of N species on the catalyst surface for the targeted oxidation of NO to NO2 is still a great challenge. Herein, a La and O dual-defective LaMnO3 (2U-L0.8MO) perovskite was fabricated using a... 详细信息

Inhibiting the deposition of N species on the catalyst surface for the targeted oxidation of NO to NO₂ is still a great challenge. Herein, a La and O dual-defective LaMnO₃ (2U-L_0.8MO) perovskite was fabricated using a urea-nonstoichiometric comodulation strategy, which achieved 97.6% NO oxidation efficiency at 210 °C and 300,000 h^-1, and was also capable of nearly 100% targeted oxidation of NO to NO₂, as well as exhibited excellent stability and recyclability. Characterizations and theoretical calculations unveiled that the urea-nonstoichiometric modulation method optimized the specific surface area and geometrical structure of perovskite, promoted the formation of La defects and oxygen vacancies (OVs), enhanced lattice oxygen activation and migration, and also facilitated the coadsorption of NO and O₂ and increased the d-band center of the perovskite. The synergistic activation of lattice oxygen and molecular oxygen along with the low-temperature oxidation mechanisms of NO was finally revealed: the comodulation strategy caused stretching and distortion of the 2U-L_0.8MO lattice, making its lattice oxygen susceptible to activation, thereby oxidizing adsorbed NO to NO₂ and simultaneously generating OVs. Afterward, O₂ would be captured by the abundant OVs on the 2U-L_0.8MO surface and converted to superoxide O₂^-, which could not only directly oxidize NO but also transform into single ¹O₂ on the adjacent Mn⁴⁺ site for the targeted oxidation of NO. This work realizes the coactivation of O₂ and lattice oxygen and also extends the understanding of the low-temperature-targeted oxidation of NO. © 2025 American Chemical Society.

关键词： cooperative activation LaMnO3 perovskite lattice oxygen activation low-temperature oxidation molecular oxygen activation targeted conversion of NO to NO2

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Discrete state Event-Driven Framework for simulation of Switching Transients in power Electronic systems

Discrete State Event-Driven Framework for Simulation of Swit...

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IEEE Energy Conversion Congress and Exposition

作者： Yicheng Zhu Zhengming Zhao Bochen Shi Jiahe Ju Zhujun Yu Liqiang Yuan Kainan Chen State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing China

Accurate and efficient simulation of device-level switching transients together with system-level dynamics in power electronic systems is challenging due to stiffness and intensive discontinuous points introduced by discrete system events. In this paper, a switching transient simulation mechanism is proposed to combine the discrete state event-driven (DSED) simulation framework and the piecewise analytical transient (PAT) model together to overcome such difficulties. key elements of this simulation framework for switching transient simulation include: 1) a commutation-unit-based (CUB) method for switching transient simulation and 2) a time-scale-decoupling (TSD) simulation mechanism. The proposed simulation framework is applied to a 50kVA solid-state transformer (SST) to verify its accuracy and efficiency. DSED simulated and experimental waveforms are in excellent agreement. Up to 5.3-fold and 717.3-fold improvements in simulation speed are achieved at the same level of accuracy compared with Simulink simulation with ideal switch models and Saber simulation with physics-based device models, respectively.

关键词： Transient analysis Switches Integrated circuit modeling Switching circuits Mathematical model Computational modeling

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Circulation and Its Influence on Meshed Multiterminal DC Distribution System 2

Circulation and Its Influence on Meshed Multiterminal DC Dis...

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2nd IEEE International Conference on power and Energy Applications, ICPEA 2019

作者： Ding, Hailong Yuan, Zhichang Guo, Peiqian Song, Meng Li, Li State Key Lab. of Secty. Contr. and Simulation of Power Systems and Large-scale Generation Equipment Department of Electrical Engineering Tsinghua University Beijing China Electric Power Research Institute of Guangdong Power Grid Corporation Guangzhou China

ISBN: (纸本)9781728115962

The application demands of direct current distribution continue to increase owing to the development of DC transmission technologies and modern distribution systems. In netted multiterminal DC distribution systems, system circulating currents often occur because of the different positive and negative line parameters. In this study, the steady- state equivalent circuit model of four-terminal grid DC distribution system is established, and the mathematical expression of system circulation is theoretically derived. The variation characteristics of circulating currents caused by inconsistencies of positive and negative circuit parameters are quantitatively analyzed. The adverse effects of the system circulating currents on the operation and protection of the DC distribution system combined with the possible parameter changes in the actual power network are analyzed. On this basis, several feasible solutions are discussed, and the above- mentioned analyses are verified by MATlab and PSCAD/EMTDC simulation. © 2019 IEEE.

关键词： MATlab

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Extended load-flow arithmetic for voltage stability analysis

Extended load-flow arithmetic for voltage stability analysis

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International Conference on power System Technology (powerCON)

作者： L. Zhu S. Zhou Y. Zhang State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing China

ISBN: (纸本)0780363388

In this paper, a novel load-flow arithmetic for voltage stability analysis is studied where models of various dynamic elements in power systems are taken into account. It simultaneously solves the load flow equation and the state equation of dynamic elements and gets both the voltage amplitude, phase of all buses and the inner state variables of the dynamic elements. In this arithmetic different limits are considered and the assumption of PV bus, PQ bus and slack bus are eliminated, so the result is closer to the real operation condition. Using a flow arithmetic based on continuation-power-flow (CPF) method, the critical point of voltage stability of the system can be computed. The proposed method is demonstrated on a test system and the results are compared with the conventional power flow method.

关键词： Arithmetic Voltage Stability analysis power system dynamics power system modeling Load flow Equations power system analysis computing power system stability System testing

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Travelling wave based single phase grounding protection for distribution system

Travelling wave based single phase grounding protection for ...

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12th IET International Conference on Developments in power System Protection, DPSP 2014

作者： Dong, Xinzhou Wang, Jun Shi, Shenxing Wang, Bin Dominik, Bak Kirby, Brian Yang, Xia State Key Lab of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing 10084 China Alstom Grid Stafford ST174LX United Kingdom

ISBN: (纸本)9781849198349

It is very difficult to correctly identify single-phase-to-ground fault (SFG) in distribution system with neutral non-effectively grounded (NNG). A novel travelling wave based singlephase-to-ground protection is proposed in the paper. The polarity of initial transient current and voltage travelling waves are used to identify the fault direction, and power frequency voltages are used to distinguish SFG from phaseto- phase fault to ensure the reliability of the protection. In the paper, wavelet transforms and module maxima theory was adopted to represent the polarity of travelling waves effectively and construct protection algorithm,. The analysis and simulation demonstrate that the protection is valid.

关键词： Wavelet transforms

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A convex hull based intertemporal loadability set approximation method

A convex hull based intertemporal loadability set approximat...

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2020 Tsinghua - HUST-IET Electrical Engineering Academic Forum

作者： Yan, Xinfei Zhong, Haiwang Tan, Zhenfei Yang, Junfeng Dept. Electrical Engineering Tsinghua University Beijing China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Beijing China Power Dispatch and Control Center State Grid Corp. of China Beijing China

ISBN: (纸本)9781839533914

The uncertainty of renewable energy sources has aroused the interests in depicting the ability of power systems to accommodate the variations. Loadability set is one of the typical methods to characterize the feasible sets of power systems with uncertainties. The existing literature on loadability set do not incorporate intertemporal constraints, while for some cases like security check, intertemporal constraints are necessary and important. This paper firstly adapts loadability set to security check, enabling it to depict the capability of power systems to accommodate load variations. Singular value decomposition (SVD) and progressive vertex enumeration (PVE) are introduced to lighten the computational burden caused by multiple periods. The computational time can be traded off with the precision of approximation to the loadability set. Case studies verify that the loadability set can be approximated with proper precision. © 2020 Institution of Engineering and Technology. All rights reserved.

关键词： Singular value decomposition

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Virtual synchronous control of grid-connected DFIG-based wind turbines

Virtual synchronous control of grid-connected DFIG-based win...

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Annual IEEE Conference on Applied power Electronics Conference and Exposition (APEC)

作者： Yangyang Zhao Jianyun Chai Xudong Sun State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing China

This paper proposes a virtual synchronous control strategy for Doubly-Fed Induction Generator (DFIG)-based wind turbines. On the basis of the proposed excitation control model orientated by rotor flux, and the P-f, Q-V droop control models which emulate the governor and exciter of synchronous machine, this paper established the basic virtual synchronous control structure for DFIG. This control strategy can provide DFIGbased wind turbines with intrinsic regulation ability of frequency and voltage without using the phase-locked loop (PLL) of the grid. Considering the power limitation under certain wind speed, the proposed adaptive droop control method realized the maximum power point tracking (MPPT) of wind turbines in steady state. simulation results demonstrate the feasibility and effectiveness of the presented virtual synchronous control for grid-connected DFIG. This control strategy can not only provide the possibility of unifying the grid-connected wind turbines as the standard synchronous power, but also decrease the negative effect on the grid frequency and voltage with high penetration of wind energy.

关键词： Wind turbines Rotors Frequency control Frequency synchronization Mathematical model Voltage control Steady-state

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Estimation and measurement of closed-loop delays in the actual WACS of Guizhou power Grid

Estimation and measurement of closed-loop delays in the actu...

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2016 IEEE power and Energy Society General Meeting, PESGM 2016

作者： Zhang, Fang Cheng, Lin Li, Xiong Min, Zeng Sun, Yuanzhang Chow, Joe H. State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing China School of Electrical Engineering Wuhan University China Department of Electrical Computer and Systems Engineering Rensselaer Polytechnic Institute TroyNY12180 United States

ISBN: (纸本)9781509041688

The characterization of the closed-loop delays in a wide-area control system (WACS) is an important foundation for further research. The method to estimate and measure the closed-loop delay in actual WACSs were proposed in this paper. Then, the closed-loop delays in the actual WACS in Guizhou power Grid in China were measured and analyzed. Also, the measured delays were used to verify the normal distribution estimation model proposed in previous research. The results indicate that the closed-loop delay in the WACS followed a normal distribution. © 2016 IEEE.

关键词： Normal distribution

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Steady-state Operation Area of VSC-HVDC Converter Station Connecting Renewable Energy Cluster by Isolated Network 10

Steady-state Operation Area of VSC-HVDC Converter Station Co...

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2020 10th International Conference on power, Energy and Electrical Engineering, CPEEE 2020

作者： Xian, Wenyuan Ding, Ran Qiao, Ying Lu, Zongxiang Li, Shangqiang Lin, Hong School of Electrical Engineering Xinjiang University Urumqi830047 China State Key Lab of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua University Haidian District Beijing100084 China State Grid Jibei Electric Power Company Xicheng District Beijing100053 China

When the large-scale renewable power island is connected to VSC-HVDC transmission system, we should figure out the steady-state operation area of VSC-HVDC converter station. Based on the equivalent model of renewable energy island, the constraints of VSC-HVDC converter station are analyzed, and a fast method for calculating steady-state operation area of converter station is presented in this paper. The influence of equivalent line impedance of renewable energy island, transformer ratio of converter station and voltage setting value of grid-connected point on steady-state operation area of converter station is analyzed. And the three-dimensional view of the steady-state operation area of the converter station under different grid-connected voltage is depicted. © 2020 The Authors, published by EDP Sciences.

关键词： HVDC power transmission

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