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作者： Yu, Hua-Peng Chen, Shui-Ming Yu, Hong-Qiao Yang, Peng-Cheng Yin, Hua Wu, Gaolin State Key Lab. of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China Chongqing Electric Power Research Institute Chongqing 401123 China

ISBN: (纸本)9781457700668

In order to limit short-circuit current and satisfy the need of relay setting, only part of the 220kV 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 use the PSCAD/EMTDC software to calculate the over-voltage on the neutral point of 4 ungrounded power transformers in Chongqing 220kV power grid, the result shows that the power frequency transient over-voltage on the neutrals may reach 178kV, 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 138.6kV. 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 723.7kV, 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 220kV transformers at the end. © 2010 Chinese Soc for Elec Eng.

关键词： power transformers

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Weather type partition method considering sequential features in photovoltaic forecasting

Weather type partition method considering sequential feature...

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6th International Conference on Renewable power generation

作者： Li, Hao Lu, Zongxiang Qiao, Ying Wang, Ningbo Ding, Kun State Key Lab. of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University Haidian District Beijing100084 China Wind Power Technology Center Gansu Electric Power Corporation Lanzhou730050 China

The prediction method based on the partition of weather types has been widely used in photovoltaic prediction. Here, the temporal characteristics of PV data is studied, the physical meaning of the sequential difference sequences is analysed, and a characteristic index system including sequential characteristics index is proposed. The weather types are partitioned based on self-organising map neural network algorithm. Case study shows that the partition method is helpful to improve the discrimination of weather types and to improve prediction accuracy. © 2017 Institution of Engineering and Technology. All Rights Reserved.

关键词： Weather forecasting

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Characteristics calculation and pattern recognition for partial discharge of cable joint

Characteristics calculation and pattern recognition for part...

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2014 International Conference on Communication Technology and Application, CTA 2014

作者： Xia, Y.F. Gui, J.F. Chen, X.Y. Gao, S.Y. Huang, J.H. Lin, J.H. Dongguan Power Breuse of Guangdong Grid China School of Electrical Engineering Beijing Jiaotong University China Department of Electrical Engineering Tsinghua University State Key Lab of Control and Simulation of Power Systems and Generation Equipments China

ISBN: (纸本)9781845649302

For PD pattern recognition, six kinds of typical cable fault models are made and tested. Characteristics are calculated from test data. Multiple statistical characteristics of PD distribution map are calculated and pattern vectors are formed. Artificial neural network is trained for recognition. Through the selection and adjustment of characteristics and network parameters, recognition effect with satisfactory result is obtained. © 2014 WIT Press.

关键词： Partial discharges

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Virtual flux based direct power control for three-level PWM rectifier 17

Virtual flux based direct power control for three-level PWM ...

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2014 17th International Conference on Electrical Machines and systems, ICEMS 2014

作者： Yingchao, Zhang Liping, Jin Yongchang, Zhang Ting, Lu Zhengming, Zhao Key Lab. of Special Power Supply of PLA Chongqing Communication Institute China North China University of Technology Power Electronics and Motor Drive Engineering Research Center China State Key Lab. of Control and Simulation of Power System and Generation Equipments Tsinghua University China

ISBN: (纸本)9781479951611

This paper presents a new control strategy for three-level neutral point clamped (NPC) pulse width modulated (PWM) rectifier without power source voltage sensors. The relationship between instantaneous power and voltage vectors is derived mathematically. Virtual flux is estimated and used to calculate the phase of the power source voltage and instantaneous power. On these bases, a direct power control (DPC) scheme for three-level PWM rectifier is presented. An optimal switching table is established, vector switching scheme and balance strategy for the neutral point potential are discussed. Variable switching frequency and dynamic process of the startup are also analyzed. Experimental results have verified the theoretical approach and the three-level PWM rectifier with proposed DPC based on virtual flux exhibits several advantages, such as simple algorithm, low costs and excellent dynamic performance. © 2014 IEEE.

关键词： Electric rectifiers

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A large-scale reactive power optimization method based on gaussian penalty function with discrete control variables

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Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering 2013年第4期33卷 68-76页

作者： Li, Zhigang Wu, Wenchuan Zhang, Boming Guo, Qinglai State Key Lab of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Haidian District Beijing 100084 China

Reactive power optimization with discrete control variables can be formulated as a mixed-integer nonlinear programming problem, which is a typical NP-hard problem in mathematics. This paper proposed a Gaussian penalty function based approach to handle discrete variables, in which the discrete variables were relaxed to continuous variables. The properties of the optimization model with Gaussian penalty function, as well as how it could be affected by parameters, were discussed. Then a practical algorithm combining nonlinear interior point method and a heuristic parameters tuning strategy was developed to solve the optimization problem. Finally, numerical experiments were taken on different systems, including IEEE standard systems and several real power systems with varying scales, to verify the robustness and practicability of the proposed method. © 2013 Chinese Society for Electrical Engineering.

关键词： IEEE Standards

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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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Electrical tree initiation and propagation in silicone rubber under long-term AC aging

Electrical tree initiation and propagation in silicone rubbe...

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2016 IEEE Conference on Electrical Insulation and Dielectric Phenomena, CEIDP 2016

作者： Zhang, Yunxiao Zhou, Yuanxiang Zhang, Ling Ming, Chen Zhang, Xu Yanchao, Sha State Key Lab of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing100084 China North China Electric Power Research Institute Co Ltd. Beijing100045 China

ISBN: (纸本)9781509046546

Electrical tree break-down is the major failure problem in cable accessories, however, mechanisms of the electrical tree initiation and propagation are still lack of deeply research, especially in silicone rubber (SIR) which is widely used as insulation material for cable accessories. Long-term aging (0- 1000 h) experiments under the different voltages were conducted to observe electrical tree initiation and propagation processes. In trees initiation stage, with increasing of applied voltage, electrical tree initiation probability becomes larger, while tree initiation time dramatically decreases. The experiment observations demonstrated four shapes of trees which are dominated. As applied voltage increasing, the numbers of electrical trees life-cycles increased and exponential relationship was found between tree length and magnitude of applied voltage. It is noted that charges, whose energy exceeding a certain critical value, destroy microstructure of dielectric accumulatively via injection and extraction, and cause electrical trees initiate when it accumulates to a visible extent. © 2016 IEEE.

关键词： Life cycle

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Wind power generation Capacity Evaluation Based on Correlation Analysis of Adjacent Wind Farms

Wind Power Generation Capacity Evaluation Based on Correlati...

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2021 IEEE Sustainable power and Energy Conference, iSPEC 2021

作者： Sun, Shuxin Qiao, Ying Lu, Zongxiang Ma, Yanhong Tsinghua University State Key Lab of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Beijing100084 China State Grid Gansu Electric Power Company Wind Power Technology Center Lanzhou730050 China

ISBN: (纸本)9781665414395

Accurate assessment of the power generation capacity of the wind farm is the key basis for incorporating it into power system scheduling and other optimizing operation activities. Traditional evaluation methods, such as benchmarking wind turbine method, have higher requirements for input data, but many wind farms in operation for many years are difficult to meet such data conditions. A new power generation capacity evaluation method based on correlation analysis of adjacent wind farms is proposed in this paper. Meteorological data and power of adjacent wind farms are used as replaced input data based on correlation analysis between the target farm with its adjacent farms. First, anticipate wind speed data and then construct the wind power curve with three different neural networks to evaluate power generation capacity. Afterwards, adjacent wind farms are used as data sources to fit the power data of the target wind farm with the application of influence radius method, inverse square distance method and bilinear interpolation method. Finally, combined with data in the actual case, investigate the advantages and disadvantages of different methods in the evaluation of power generation capacity. © 2021 IEEE.

关键词： Time delay

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Equivalent capacity of the lower voltage ride through for wind farm from overcurrent protection in power collection lines

Equivalent capacity of the lower voltage ride through for wi...

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11th IET International Conference on Developments in power systems Protection, DPSP 2012

作者： Wang, Bin Dong, Xinzhou Bo, Zhiqian State Key Lab. of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China Alstom Grid Stafford ST17 4LX United Kingdom

ISBN: (纸本)9781849196208

Magnitude and duration of voltage sags are the most important two factors to the Lower Voltage Ride Through (LVRT) capacity of the wind generator. Since most voltage sags are caused by the system faults, and sag durations are controlled by the tripping time of overcurrent relay in power collection lines based on the sags' magnitude. The specification of the LVRT capacity of wind generator is introduced into the operation characteristics of the relay in power collection lines. The evaluation model of equivalent LVRT capacity to overcurrent protection is proposed in paper, and the equivalent LVRT capacities from zone I and zone II relay are quantified. Improvement measures are also proposed.

关键词： Overcurrent protection

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Retraction notice to “Multi-objective planning of microgrid based on renewable energy sources and energy storage system” [J. Energy Storage 68 (2023) 107803]

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Journal of Energy Storage 2025年 117卷

作者： Hao Tian Keqing Wang Xiufeng Cui Zexi Chen Ergang Zhao Sara Saeedi School of Automation Wuxi University Wuxi 214105 China State Key Lab of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100086 China Beijing Sifang Engineering Co. Ltd Beijing 100085 China State Grid Beijing Urban Power Supply Company Beijing 100034 China Electrical Engineering Department Sun-Life Company Baku Azerbaijan

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