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Novel connection scheme of backup power supply adaptive to Distribution Line Non-Communication Protection and new criterion for high voltage and large capacity induction motor

Novel connection scheme of backup power supply adaptive to D...

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2009 Asia-Pacific power and Energy Engineering Conference, APPEEC 2009

作者： Liu, Kun Dong, Xinzhou Bo, Zhiqian State Key Lab of Control and Simulation of Power System and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing 100084 China AREVA T and D Automation Stafford ST17 4LX United Kingdom

ISBN: (纸本)9781424424870

This paper presents a new practical backup power supply connection scheme for Distribution Line Non-Communication Protection (DNCP). simulation tests have been conducted using the Alternate Transient Program (ATP) with respect to a typical single circuit breaker multi-section system. The results prove that the new scheme is able to not only recover the power supply of loads on healthy lines automatically, but also create disturbances in favor of Accelerated Over Current (AOC) criterion. Aiming at the failure of Directional Under Voltage (DUV) criterion derived from high voltage and large capacity induction motor load, a novel criterion using the increment of reactive power is proposed. © 2009 IEEE.

关键词： Induction motors

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Study on Over-Voltage of 220 kV Transformer＇s Neutrals and Protection Strategy

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Journal of Energy and power Engineering 2011年第11期5卷 1102-1108页

作者： H.P. Yu S.M. Chen P.C. Yang H. Yin G.L. Wu State Key Lab of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University Beoing 100084 China Chongqing Electric Power Research Institute Chongqing 401123 China

In order to limit short-circuit current and satisfy the need of relay setting, only part of the 220 kV power transformer is grounded, so on the neutrals of ungrounded transformers will appear the over-voltage. Currently the value of over-voltage on transformer neutral point and the corresponding protection strategy is based on theoretical formula. This article uses the PSCAD/EMTDC software to calculate the over-voltage on the neutral point of 4 ungrounded power transformers in Chongqing 220 kV power grid. The result shows that the power frequency transient over-voltage on the neutrals may reach 178 kV. If the single-phase grounding fault occurs in ungrounded power system, the power frequency over-voltage on the neutrals will be more serious and rise to 138.6 kV. Non-full phase operation may cause serious ferro-resonance over-voltage on the neutrals of no-load transformer, which may last for seconds and may rise to 723.7 kV, causing serious threat to the transformer neutrals and line-side equipment. The article also studies the gap parameter which should be taken on the neutrals of 220 kV transformers at the end.

关键词： Neutral point power transformer arrester gap power frequency over-voltage lightning over-voltage.

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Evaluation of Information Value for Solar power Plants in Market Environment

Evaluation of Information Value for Solar Power Plants in Ma...

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

作者： Bohong Wang Qinglai Guo Tianyu Yang Hongbin Sun Tsinghua University State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing China

ISBN: (数字)9781728196060

ISBN: (纸本)9781728196077

Uncertainty is not negligible in power systems, it affects the generation, transmission and utilization of electricity. Especially in electricity markets, the randomness and variability of generation or load will cause notable forecast errors and lead to economic losses of market participants. Due to the data explosion in recent few years, data have gradually become valuable information that can be mined, analyzed, and applied. Meanwhile, the utility that more abundant and accurate information could eliminate uncertainty is emerging. In this paper, solar power plants (SPPs) are selected as the object, the general mechanism in electricity markets is briefly introduced and the corresponding market optimization model is constructed. With the optimization model analytically solved, the impact of uncertainty is analyzed and the expressions of information value are derived. Besides, uniform, normal, logistic, and Laplace distribution are used in the evaluation of information value and compared. Finally, the case study is conducted to verify the theoretical results of information value and illustrate its significance.

关键词： Economics Uncertainty System integration Electricity supply industry power systems Solar power generation Optimization

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Autonomous Decentralized control of Distributed generation using Multi-Agent Reinforcement Learning 11

Autonomous Decentralized Control of Distributed Generation u...

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11th International Conference on Innovative Smart Grid Technologies - Asia, ISGT-Asia 2022

作者： Liul, Jian Xul, Weifeng Liul, Zhijun Ful, Guanhua Jiang, Yunpeng Wang, Jun Zhejiang Electric Power Co. Ltd. Hangzhou Power Supply Company of State Grid Hangzhou310016 China Wuxi Research Institute of Applied Technologies Tsinghua University China Tsinghua University State Key Lab of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Beijing100084 China

ISBN: (纸本)9798350399660

With the large-scale integration of distributed generations (DGs), a centralized control approach is being challenged concerning communication efficiency, resiliency to communication failure, privacy, and scalability. An autonomous decentralized control for DGs in distribution networks is proposed to ensure privacy while also reducing the computational burden. Meanwhile,a multi-agent reinforcement learning method considering privacy protection constraints is developed to solve the autonomous decentralized control problem. The effectiveness of the proposed control method is verified by the numerical example of the modified 141-bus distribution system test-feeder. © 2022 IEEE.

关键词： Distributed power generation

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Transmission expansion planning modelfacilitating low-carbon power sources' development

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Dianwang Jishu/power System Technology 2015年第10期39卷 2725-2730页

作者： Du, Ershun Sun, Yanlong Zhang, Ning Chen, Songsong He, Guixiong Kang, Chongqing State Key Lab of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing100084 China China Electric Power Research Institute Haidian District Beijing100192 China

power planning oriented to low-carbon can relief 'carbon lock' effect and facilitate to achieve low-carbon power system. For tapping low-carbon potential of power grid, this paper comprehensively analyzes corresponding low-carbon elements and proposes a novel transmission planning model for promoting low-carbon power sources' development. These analyses include facilitation of integration and accommodation of renewable power, life cycle carbon emission process and reduction of grid loss. Based on multi-scenario technique, the proposed model minutely simulates system operation process considering both typical and extreme operation constrains. Through inequality separation and piecewise linearization, original model is converted into a large scale mixed integer linear programming (MILP) model. Case study of Jiangsu provincial grid verifies validity of the proposed model. ©, 2015, power System Technology Press. All right reserved.

关键词： Life cycle

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Design and implementation of automatic voltage control system applied to a power grid in Northeast US

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Dianwang Jishu/power System Technology 2013年第2期37卷 349-355页

作者： Zhang, Mingye Guo, Qinglai Sun, Hongbin Tong, Jianzhong Zhang, Boming Wu, Wenchuan Wang, Bin State Key Lab. of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China PJM Interconnection PA 19403 United States

With the raising of requirement of power grid operation to voltage control and reactive power management level, automatic voltage control (AVC) becomes a hot spot in the research. Due to the constraints in the management mode, the applied research of AVC is hitherto a blank in North America power grids. An AVC system, which is suitable to special management modes of a certain interconnected power grid in Northeast U. S. and can meet the demand of on-line operation, is designed and implemented. In the designed system, phase shifter models are added into power flow modules and during the computation of control strategy by optimal power flow (OPF) the static security constraints after the assumed faults are considered. Both the data and assessment results of long-term on-line trail-operation show that the reactive power and voltage level of the interconnected power grid can be improved by applying the designed AVC system, and both security and economy of the interconnected power grid can be enhanced.

关键词： Electric power system control

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Distribution line automation system based on non-communication protection in the case of symmetrical fault

Distribution line automation system based on non-communicati...

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International Conference on Advanced power System Automation and Protection (APAP)

作者： Diqing Yin Kun Liu Xinzhou Dong Shenxing Shi Gang Xu Kai Wang North City Branch of Shanghai Power Company 200072 China Status Key Lab of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China

Distribution line non-communication protection (DNCP) can quickly and selectively isolate unsymmetrical fault, but the performance of this distribution line automation system is not satisfying in the case of symmetrical fault. This paper proposes a scheme which can quickly isolate symmetrical fault and block the operation of BPS: DNCP which is closed to the source can operate instantaneously, that can avoid overheating damage of electrical equipment; when the magnitude of voltage falls, BPS will detect the magnitude of negtive voltage two cycles ago to make a decision, that can avoid the process of connecting to permanent fault and tripping again for the ring main unit. EMTP simulation results show the effectiveness of the scheme.

关键词： Circuit faults Circuit breakers Relays Automation power supplies Induction motors

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First stirling-type cryocooler reaching lambda point of ~4He(2.17K) and its prospect in Chinese HUBS satellite project

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Science Bulletin 2019年第4期64卷 219-221页

作者： Jue Wang Changzhao Pan Tong Zhang Kaiqi Luo Xiaotong Xi Xianlin Wu Jianpeng Zheng Liubiao Chen Junjie Wang Yuan Zhou Hai Jin Wei Cui University of Chinese Academy of Sciences CAS Key Laboratory of Cryogenics Technical Institute of Physics and Chemistry Chinese Academy of Sciences Laboratoire National de Métrologie Et d'essais-Conservatoire National des Arts et Métiers (LNE-Cnam) State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University Department of Physics and Center for Astrophysics Tsinghua University

The issue of "missing baryons” is always an unsolved mystery in galaxy cosmology, and an important reason for the great uncertainty of the galaxies' formation and evolution. To find the "missing" baryons, extra high-resolution spectral observation and imaging of the soft X-ray band (<1 kev) is required. However, the existing observation methods cannot meet this requirement. Therefore, Tsinghua University leads and proposes the Chinese "Hot Universe Baryon Surveyor (HUBS)" satellite program.

关键词： missing baryons HUBS missing

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Design and engineering application of automatic discovery system for critical flowgates and security operation rules in power grids

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Dianli Xitong Zidonghua/Automation of Electric power systems 2015年第1期39卷 117-123页

作者： Zhao, Feng Sun, Hongbin Huang, Tianen Guo, Qinglai Wu, Wenchuan Wen, Bojian Department of Electrical Engineering Tsinghua University Beijing100084 China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing100084 China Guangdong Power Grid Power Dispatching Control Center Guangzhou510600 China

The framework of an automatic discovery system for critical flowgates and security operation rules in the power grid is designed. Based on the real-time operation data of the power grid, the system is able to automatically find the critical flowgates adapted to the online operation state of the grid. By using the automatic learning method, the system can find the fine rules of critical flowgates as the security operation knowledge of the grid. The functions of the core modules of the system are described, including online automatic discovery of critical flowgates, online calculation of limit transmission capacity of critical flowgates, online generation of mass simulation samples, feature selection, automatic discovery of security operation rules of the power grid. The online application of the system has been realized in Guangdong power grid. The application effect shows that the system is able to generate the security operation knowledge fast enough and refresh it every 15 minutes for online application as required. Meanwhile, the knowledge is capable of not only covering the existing security operation knowledge formulated by experts offline, but also finding new knowledge adapted to the online power grid operation mode, while improving the power grid security and economy.

关键词： Electric power transmission networks

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Creating multivariable response surfaces by the two-stage adaptive sampling techniques and its application in the optimization of grounding grids

Creating multivariable response surfaces by the two-stage ad...

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作者： Zou, J. Guo, J. Zhang, B. He, J.L. Lee, J. Chang, S. State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing 100084 China Electrical Environment and Transmission Group Korea Electrotechnology Research Institute Changwon 641600 Korea Republic of

A fast and efficient adaptive sampling algorithm to obtain the response surface of multivariable objective function is presented. The algorithm is divided into two stages. First, starting with a low-rank interpolation model, the technique systematically increases the rank by optimally choosing new support points in the areas of the highest error until the required accuracy is achieved. Second, the verification between the fitted result and the exact one is carried out. The optimization of grounding grids is performed to show the effectiveness of the proposed algorithm. © 2006 IEEE.

关键词： Algorithms

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