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International Conference on Magnetics (INTERMAG)

作者： J. Li S. Wang H. Gao M. Liu J. Hong State Key Laboratory of Control and Simulation of Power System and Generation Equipments Tsinghua University Beijing China State Key Laboratory of Reliability and Intelligence of Electrical Equipment Hebei University of Technology Tianjin China

Body: power transformers and reactors are important devices in power transmission systems. But their cores and windings could produce vibration and acoustic noise by magnetostrictive effect, Maxwell electromagnetic stress and Lorentz force. Noise has become a bad environmental pollution source in some situations, and its vibration and noise reduction has become an urgent problem need to be solved. The shapes, materials, magnetostriction and joints forms of iron cores, the limitations of test, modeling, and experimental measurement of vibration and noise characteristic, are all the difficult reasons to analyze the vibration and acoustic noise of transformers and reactors. 1. The magnetostrictive modeling can be divided into two steps based on the magnetic field force and materials deformation, so the magnetic field force will be fed into the structural finite element with Maxwell electromagnetic force produced on the interface between the iron core and the air to calculate the deformation of the magnetic materials and to make the model more general and consistent. In order to fully verify the correctness of the model in the magnetostrictive analysis, and to ensure the simplicity of test and avoid unnecessary interference factors, the most simple magnetostriction tests will be carried out by using a single closed circle or rectangular electrical steel sheet, as shown in Fig. 1(a). The tests will measure the relationship between magnetostriction and magnetic field of different magnetic materials, different saturations, different sizes and different shapes. 2. The joint is a necessary form for the stacking of large transformer iron cores, and the main joint form is the step jiont at present. The introduction of the joints causes the magnetic force lines to flow through the different laminations and to make the local magnetic field complicated. From simple to complex process is adopted in this paper, and the verification is gradually complicated. Based on the study of a

关键词： Magnetics Conferences

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Two-stage heuristic-correction for dynamic reactive power optimization based on relaxation-MPEC and MIQP

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Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering 2014年第13期34卷 2100-2107页

作者： Ding, Tao Guo, Qinglai Bo, Rui Sun, Hongbin Wu, Wenchuan Zhang, Boming Yao, Zhengyi State Key Lab. of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China Midwest ISO St. Paul 55108 United States Baoji Power Supply Bureau Baoji 721004 Shannxi Province China

To achieve a fast approach to the dynamic reactive power optimization model, a mixed integer nonlinear programming model was set up, with consideration of the discrete reactive power equipment operation limit and power grid security constraints, to minimize the transmission losses. Furthermore, a method called heuristic search and variable correction was proposed that for the first stage, the discrete variables are relaxed into continuous ones, which leads to an optimization model with equilibrium constraints. According to the optimal value of relaxed model, a mixed integer quadratic programming model is formulated to minimize the objective of approximation variance, satisfied the discrete switching operation constraints in primary model. For the second stage, the continuous variables are redressed with respect to the determined discrete variables. The impact of adjustment step and operation limit on the optimal solution was fully studied in IEEE 14-bus test system. Besides, the result of IEEE 30, 57, 118 test systems show that an optimal solution can fast be obtained by proposed method, and the precision satisfies the actual engineering, which can also employ the parallel technology. © 2014 Chinese Society for Electrical Engineering.

关键词： Integer programming

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Discussion of protection and cascading outages from the viewpoint of communication

Discussion of protection and cascading outages from the view...

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

作者： RunBin Cao Xinzhou Dong Bin Wang Kun Liu Status Key Lab of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China

power grid and communication network, which depends on each other to provide proper functionality, are becoming more and more coupled together. Failure of a fraction of nodes in communication networks may lead to a failure even a cascade of failures in power grid. Wide area protection is highly dependent on communication. The failure of communication in some part of wide area protection system will affect the realization of the function to prevent cascading outages and result in serious consequences. Based on Manchester, OPA and hidden failure cascading failure models and considered the feature of relay protection, an improved cascading failure model is established. Then it is used to analyze the dynamic process of communication fails in wide area protection system and IEEE 30 bus system is employed to demonstrate the efficiency of the proposed method. Results show that communication failure in protection system will accelerate the cascading outages of power grid. Effective solutions to reduce the communication risk are discussed. The work of this paper is available for reference to analyze the process of cascading outages and design protection system preventing cascading outages.

关键词： power system faults power system protection Load modeling Wireless application protocol power system stability Load flow power grids

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Communication test and analysis of integrated protection system in digital substation

Communication test and analysis of integrated protection sys...

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2011 International Conference on Advanced power System Automation and Protection, APAP 2011

作者： Wu, TingTing Shi, ShenXing Wang, Bin Zhou, YunHai Dong, XinZhou Liu, Kun Yang, YueLin School of Electrical Engineering and Renewable Energy China Three Gorges University Yichang 443000 China State Key Lab. of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China College of Information and Electrical Engineering CHINA Agricultural University Haidian District Beijing 100083 China

ISBN: (纸本)9781424496198

The development of digital substation provides new opportunity for integrated protection. However, the realization of integrated protection is constrained by serial communication between process level and bay level. Based on developed digital integrated protection and control system platform, the result of a physical simulation test concerning communication system reveals the problem of communication instability and packet loss. In this paper, the impact of GPS exerted on stability of integrated protection is tested and analyzed. Without GPS time setting of Merging Unit(MU) in different bay, the integrated protection system will lose data in one minute after running. With GPS, the communication is stable and reliable, but the time interval between two packets in a cycle is quite long. Since sampling of MU in different bay is synchronized by GPS, the availability of integrated protection system is directly affected by communication of integrated protection in digital substation. © 2011 IEEE.

关键词： Packet loss

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power transmission mode to promote low-carbon development of load center

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Dianwang Jishu/power System Technology 2015年第3期39卷 663-668页

作者： Tian, Xin Sun, Yanlong Niu, Xinsheng Zhu, Xiubo Zhao, Guangfeng Shandong Power Economic Research Institute Shandong Electric Power Company Ji'nanShandong Province250001 China State Key Lab of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing100084 China State Grid Shandong Electric Power Company Ji'nanShandong Province250021 China

Regarding the power transmission mode from energy base to load center as the heart of the matter, a joint optimal operating model for both sending- and receiving- end power grids is established. In this model, the carbon emission is taken into the total system operation cost in the form of economic costs and taking the minimized total system operation cost as the objective the operation of the tie line and the generating unit in the receiving end power grid is scheduled. Based on the planning parameters for the power transmission from XilinGol League to Shandong, the case study on the application of the proposed model is performed and the results show that through reasonable power transmission mode the wind power accommodation space of the receiving end power grid can be fully utilized to accommodate the wind power generated in the sending power grid, thus the system operating cost is reduced while the low carbon development of power grid can be promoted effectively. ©, 2015, power System Technology Press. All right reserved.

关键词： Wind power

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A fast transient simulation model of DFIG based on the piecewise averaging method

A fast transient simulation model of DFIG based on the piece...

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2nd IET Renewable power generation Conference (RPG 2013)

作者： G. Feng Y. Xu Y. Chen H. Gao L. Chen Tsinghua University Beijing Beijing CN State Key Lab of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Beijing 100084 China

ISBN: (纸本)9781629936017

Due to the power electronic devices in doubly fed induction generators (DFIG), it is very time consuming to simulate the electromagnetic transients of DFIG using its detailed model. Thus it is necessary to have appropriately simplified model of DFIG that maintains desirable accuracy. In this paper, the piecewise averaged model of PWM converters is introduced and applied to the modelling of DFIG. The proposed model divides the simulation time interval into switching periods and recalculates the averaged state equations of PWM converters in each switching cycle. In addition, a predictorcorrector based EMTP algorithm is designed to iteratively solve the model. Instead of treating switching events at the time points when they happen, the new algorithm solves all the switching instants in a switching cycle at the same time, which avoids frequency modification of the system conductance matrix and speeds up EMT simulations of DFIG. simulation results of a single-machine infinity bus system with a DFIG show that the proposed model and algorithm can achieve satisfactory accuracy and efficiency.

关键词： Average modelling Doubly fed induction generators Electromagnetic transient simulation

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Traveling waves based protection relaying of power lines

Traveling waves based protection relaying of power lines

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

作者： Shenxing Shi Xinzhou Dong Shiyong Wang Status Key Lab of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China

With high speed data sampling technology development, fault generated high-frequency signals can be got, in which fault generated traveling waves reflects fault location, fault type and faulted equipment so on from different ways of traditional power-frequency information. Fault generated traveling waves may help to improve protection relaying. The paper will review fault generated traveling waves and its physical base at first. Then two cases will be presented to exemplify the advantage of traveling waves based protection relaying. One is that fault generated traveling waves with the speed of light can be used to protect UHV long transmission lines independent of capacitive charging current. The other is traveling wave will be applied to detect single-phase-to-ground fault in power distribution system with neutral non-effectively grounded. At last the paper will conclude with implementation of traveling wave based protection relaying.

关键词： Relays Circuit faults Integrated circuit modeling power transmission lines

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Research on Equalization Effect of Dynamic Reconfigurable Battery Management System

Research on Equalization Effect of Dynamic Reconfigurable Ba...

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Sustainable power and Energy Conference (iSPEC)

作者： Yuxiang Wan Lin Cheng Yi Jiang Zhidong Wang Mei Liu State Key Lab. of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China State Grid Economic and Technological Research Institute Corporation Limited State Grid Corporation of China Beijing China

ISBN: (纸本)9781728149318

The battery differences not only affect the reliability and security of battery packs but also accelerate the decline of the packs' life. Although battery management systems (BMS) and equalization circuit can be used to balance the differences, only the whole battery pack can be protected with high-cost and complex circuits. Dynamic reconfigurable battery management system (DRBMS) based on networked control has a simple principle and can shield the differences of battery cells. This paper designs experiments for the dynamic reconfigurable battery network technology and makes a contrast with the traditional BMS. Through the analysis of voltage, SOC difference and dynamic resistance during charging and discharging, the results show that DRBMS has better voltage and capacity equalization effect than BMS. The cells of paralleled battery packs can be fully charged/released in DRBMS. It is also verified that DRBMS is applicable on decommissioned bus battery packs which are of larger differences and the ladder utilization.

关键词： dynamic reconfigurable battery management equalization effect decommissioned battery battery difference Battery Pack Battery management systems configurability Dynamic resistance Equalization Batteries network control

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Stability Analysis and Braking System Design of Icebreaker Propulsion System Based on 3L-NPC Inverter

Stability Analysis and Braking System Design of Icebreaker P...

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Smart power & Internet Energy systems (SPIES), International Conference on

作者： Nianzhou Liu Nan Fu Pengfei Xie Wenfeng Long Kui Wang Yongdong Li Science and Technology on Ship Integrated Power System Technology Laboratory Wuhan Institute of Marine Electrical Propulsion Wuhan China State Key Lab of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China

The icebreaker is important in the polar scientific investigation and resource exploration. There will be pulse and periodic load during the continuous icebreaking process, which may affect the propulsion system of the icebreaker. This paper mainly analyzes the effect of the impact load on the three-level neutral point clamped (3L-NPC) inverter with diode front-end, and demonstrates the relationship between the impact load and the feedback energy. Moreover, the choice of the resistance of the braking resistor is briefly discussed. The simulation results are given at last, which verify the rationality and correctness of the theoretical analysis.

关键词： Resistors Resistance simulation Energy Propulsion Inverters Stability analysis

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Research on system protection with local information to prevent power grid blackouts

Research on system protection with local information to prev...

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

作者： Bin Wang Xinzhou Dong Kun Liu Runbin Cao Status Key Lab of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China

Aimed at power system large-scale blackouts, the paper firstly analyzes the existing problems of current protective relaying and emergency control in power grid. A novel system protection based on local information, protecting both the equipment and power system secure is then proposed, which scheme consists of: identification of fault flow transferring identification, adaptive overload protection and active load shedding strategy. The processes and system structure are introduced, and the following research points are also discussed in this paper.

关键词： Helium Security

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