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IEEE General Meeting power& Energy Society

作者： Hanchen Xu Can Wang Chao Lu Zhigang Lu State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China Electric Power Research Institute of China Southern Power Grid Guangzhou China

The random and intermittent nature of wind power (WP) makes the integration of large-scale wind farms into power system problematic. The energy storage system (ESS) is an effective means to smooth the WP. This paper presents a novel Kalman filter (KF) based adaptive wind power smoothing method to determine the power output of an ESS. ESS capacity can be significantly reduced by adjusting the parameters of KF adaptively according to the WP fluctuation. Meanwhile, a fuzzy logic controller is introduced to manage the remained energy level (REL) of the ESS. By considering the current WP fluctuation, the REL and the power output of the ESS together in the controller, the REL can be successfully managed to a reasonable range without deteriorating the WP fluctuation. A test case based on data from an actual wind farm validated the effectiveness of the proposed method.

关键词： Fluctuations Wind power generation Energy storage Wind farms Kalman filters Fuzzy logic Smoothing methods

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Automatic discovery method of power system critical flowgates considering multiple security themes in power grid

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Dianwang Jishu/power System Technology 2014年第5期38卷 1169-1174页

作者： Zhao, Feng Sun, Hongbin Tan, Yan Guo, Qinglai Guo, Wenxin State Key Lab of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China Guangdong Electric Power Control Center Guangzhou 510600 Guangdong Province China

Based on summarizing the features of selecting critical flowgates in actual power grid, an automatic discovery method of power system critical flowgates considering multiple security themes in power grid is proposed. Based on topological structure of power grid and online power flow, the electric partitioning of power grid is performed and different types of critical flowgates are selected according to different security theme: according to the demand on transient security theme the long-distance transmission channel composed by tie line between electric partitionings is chosen as critical flowgate;according to the demand on thermal stability theme, the transmission channel composed of high voltage transmission lines with high transmission capacity, which interact each other obviously, is chosen as critical flowgate;according to the thermal stability at load side the transmission channel composed of low voltage transmission lines with higher transmission capacity, which interact each other obviously, is chosen as critical flowgate. Taking Guangdong power Grid in China as testing example, test results show that the proposed method considers common security themes in power grid accurately and different kinds of critical flowgates can be attained;the obtained critical flowgates not only conform to a posteriori critical flowgate given by experts in the field of power grid operation, and new critical flowgates can be discovered, besides, the discovery results are reasonable and creditable.

关键词： Thermodynamic stability

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Dynamic simulation based on Jacobian-free Newton-GMRES methods with adaptive preconditioner for power systems

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Science China(Technological Sciences) 2013年第8期56卷 2037-2045页

作者： HUANG ShaoWei CHEN Ying SHEN Chen MEI ShengWei State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments(Department of Electrical Engineering Tsinghua University)

Dynamic simulation is one of the most complex and important computations for power systems *** solutions based on normal Newton iterations almost all depend on evaluations of Jacobian matrixes,which increases the programming complexity of and limits the parallelizability of the whole *** this paper,a new adaptive preconditioned Jacobian-free Newton-GMRES(m)method is proposed to be applied to dynamic simulations of power *** new method has totally Jacobian-free characteristics,which saves calculations and storages of Jacobian matrixes and features strong ***,several speedup strategies are introduced to enhance efficiency and parallelizability of overall *** tests are carried out on IEEE standard test systems and results show that in series computing environment,simulations based on the proposed method have comparable speed to those based on classical Newton-Raphson methods.

关键词： dynamic simulation Newton-GMRES preconditioner power system

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Phase-Shift control of Isolated Bidirectional DC-DC Converters for Unidirectional power Flow

Phase-Shift Control of Isolated Bidirectional DC-DC Converte...

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IEEE Energy Conversion Congress and Exposition

作者： Junjie Ge Zhengming Zhao Junchao Ma Fanbo He Liqiang Yuan Ting Lu State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University 100084 Beijing P. R. China

ISBN: (纸本)9781479957774

In the conventional phase-shift control of isolated bidirectional DC-DC converters, the phenomenon of power backflow is quite obvious. General improved phase-shift control methods can reduce the power backflow of the input. However, they do not take the power backflow of the output into consideration. In this paper, a novel phase-shift control of isolated bidirectional DC-DC converters for unidirectional power flow is proposed. It can eliminate the power backflows of both the input and the output at the same time. Furthermore, the converters in the proposed phase-shift control can achieve the zero-current switching in the whole power rang. Experimental results from a prototype verify the feasibility and validity of the proposed control method, and show superior performance.

关键词： DC-DC power converters Voltage control Load flow control systems Educational institutions Prototypes

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Low-carbon power grid index system and evaluation method

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Dianli Xitong Zidonghua/Automation of Electric power systems 2014年第17期38卷 157-162页

作者： Sun, Yanlong Kang, Chongqing Chen, Songsong Meng, Junxia Lu, Chang Luo, Jinshan 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 China Electric Power Research Institute Beijing100192 China State Power Economic Research Institute Beijing102209 China

The importance of establishment of the low-carbon power grid index system and its comprehensive evaluation model for the development of the low-carbon power grid is firstly discussed. Based on the concept of life cycle analysis, a comprehensive low-carbon power grid index system and a more refined central index system are designed in consideration of different aspects of coverage, and the meaning of each index explicated in detail. Furthermore, a comprehensive evaluation method is designed for the quantization of the low-carbon developing condition of different power grids. Finally, an example analysis is conducted based on the statistical data of some domestic power grids to demonstrate the actual application of the evaluation model. © 2014 state Grid Electric power Research Institute Press

关键词： Electric power transmission networks

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Simplified mathematical model of inter-turn short circuit of field windings in hydro-generators and its application

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Science China(Technological Sciences) 2013年第4期56卷 898-909页

作者： HAO LiangLiang WU JunYong SUN YuGuang WANG XiangHeng School of Electrical Engineering Beijing Jiaotong University State Key Lab of Control and Simulation of Power Systems and Generation Equipment Tsinghua University

Inter-turn short circuit of field windings is a common electrical fault of *** is an important method of investigating the fault and providing data support for fault ***,huge numbers of pole pairs and damper loops in large hydro-generators would lead to lengthy calculation time,hindering scientific research and engineering *** deal with this problem,we analyze a theoretical basis for a damper winding simplified model and then propose an equivalent treatment *** the analysis of steady-state current harmonic characteristics of generators with different stator winding configurations during the fault,the simplified models suitable for steady-state calculation are derived from two aspects,namely,additional rotor harmonic current frequency characteristics and the relationship of the amplitude as well as the phase of each branch current of the *** calculation and experimental results of the two simplified models are then compared to verify the models' correctness.A calculation example of the Three Gorges left bank VGS generator shows few deviations between the calculation results of the simplified model and the original ***,the calculation time using the simplified model is 1/1500 that using the original model,which provides a more effective tool for on-line fault ***,the sensitivity-verification application of the fault-monitoring scheme based on the stator steady-state unbalanced current RMS is *** result shows that the scheme can monitor two-turn short circuits of field windings in the Three Gorges generator and provide high sensitivity.

关键词： hydro-generator field windings inter-turn short circuit simplified model on-line monitoring

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Design optimization of ferrite rings for VFTO mitigation

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IEEE Transactions on power Delivery 2014年第99期PP卷 1-1页

作者： He, Jiaxi Guan, Yonggang Liu, Weidong Chen, Weijiang Li, Zhibing Department of Electrical Engineering State Key Lab of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing100084 China State Grid Corporation of China Beijing100031 China China Electric Power Research Institute Beijing100192 China

Very-fast transient overvoltage (VFTO)-related problems are raising growing concerns in China with the development of ultra-high voltage. The practice of fitting ferrite rings on gas-insulated switchgear busbars for VFTO mitigation has long been proposed but few investigations on its design optimization were conducted. Based on theoretical analysis of the simplified model, the optimal damping condition of ferrite rings is proposed, which is conducive to the type selection. The number of rings to be employed to ensure visible suppressing effects is given through simulations and the influence of the saturation is discussed. Impact on the power frequency is analyzed to be negligible. Finally, comparisons aremade between the theoretical conclusions and existing experiment results, which approve the optimal damping condition and agree with the number of rings to be employed. © 2014 IEEE.

关键词： Electric switchgear

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Discussion on tower shunt coefficient of UHV DC transmission line under lightning stroke

Discussion on tower shunt coefficient of UHV DC transmission...

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International Conference on Lightning Protection (ICLP)

作者： S Chen J Hu B Zhang Y Yin M Hua State Key Lab of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing China China Electric Power Research Institute Beijing China Tibet Electric Power Research Institute Lhasa China

ISBN: (纸本)9781479935451

The development of UHV transmission technology brings longer transmission distance, higher towers and more complicated terrain along the transmission lines, which make the shunt performance of transmission line under lightning stroke more diversiform compared to conventional ones. This paper discusses the effects of factors, such as lightning current waveform, footing resistance, transmission line span etc., on the shunt coefficient of UHV DC transmission lines, which is of great significance for setting out lightning-proof measures as well as the location of lightning stroke point. It is referred that lightning current waveform especially its front time as well as tower footing resistance plays a significant role in determine of the tower shunt coefficient under lightning stroke. As the results indicates, the shunt coefficient of ground wire gets larger as the footing resistance increases while it decreases first and then increases as the front time of the lightning current waveform increases. The shunt coefficient of tower is just the opposite.

关键词： EMTDC Educational institutions Poles and towers Wires Wide area networks Lightning

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Application of the complex algorithm in PMU-only state estimaiton

Application of the complex algorithm in PMU-only state estim...

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International Conference on power System Technology (powerCON)

作者： Yunfeng Cheng Chao Lu Kun Men Liang Tu the State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghual University Beijinz P.R. China the Academy of China Southern Power Grid Guangzhou P.R. China

China's electrical grid has installed more than 2500 sets of phasor measurement unit (PMU), covering almost all the 500 kV and above and part of the 220 kV substations, which in sure observable of the ultra-high voltage power network and provide mass data for system analysis. However, PMU measurements may contain bad data and the precision of measurements especially phase need to be further improved. state estimation is an effective method to deal with data contaminated by noise and bias. Therefore, it's of great significance to study the PMU-only state estimation (POSE) problem. The real number equations based on the rectangular coordinate system and weighted least squares (WLS)algorithm are the general method to solve the POSE problem at present, which need to convert phasors into their real and imaginary parts, thus enlarging the size of the coefficient matrix which decreases the computational efficiency. In this paper, complex number equations for the POSE problem are established and the complex number weighted least squares (CWLS) estimation model is built to solve the equation directly in the complex domain which needs no phasor converting. The error characteristics of PMU measurements in the complex domain are analyzed in depth which give a guidance of choosing weights and illustrate the robustness of the CWLS to phase. Test results demonstrate the contrast analysis between the CWLS and the WLS from the perspectives of estimation time, estimation accuracy and adaptability to different error levels, which shows that the performances of the CWL Sare better than the WLS. The robustness of the CWLS to phase is also showed in the tests.

关键词： Phasor measurement units Measurement errors Measurement uncertainty Phase measurement Current measurement Voltage measurement Equations

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On Dispatching power systems with Significant Wind generation Using Disturbance Feedbacks

On Dispatching Power Systems with Significant Wind Generatio...

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第三十二届中国控制会议

作者： WEI Wei MEI Shengwei LIU Feng State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department of Electrical EngineeringTsinghua University

ISBN: (纸本)9781479900305

With the rapid development of renewable energies,especially wind power,how to manage unexpected generation variations economically and reliably in dispatch has become crucial for modern power *** address this issue,this paper presents an affine disturbance feedback robust dispatch(ADF-RD) methodology for power systems with large scale wind power integration in the framework of adjustable robust optimization(ARO).This methodology divides the dispatching process into pre-dispatch and ***-dispatch decision immunizes against all possible realizations of uncertainties in a set,while re-dispatch which can be regarded as a feedback will be adaptively adjusted using an affine function with respect to the realized uncertainty in real *** ADF-RD methodology is applied to an hourly ahead dispatch(HAD) *** effectiveness and efficiency of the proposed ADF-RD methodology are demonstrated by numerical experiments carried on a five-bus system.

关键词： Adjustable robust optimization affine disturbance feedback power system dispatch uncertainty wind power

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