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

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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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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DCT representations based appearance model for visual tracking

DCT representations based appearance model for visual tracki...

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IEEE International Conference on Robotics and Biomimetics

作者： Hongkai Chen Weizheng Zhang Xiaoguang Zhao Min Tan State Key Laboratory of Management and Control for Complex Systems Chinese Academy of Sciences Beijing China State Grid Henan Electric Power Company Zhengzhou China

ISBN: (纸本)9781479973989

In this paper, we present a simple yet effective visual tracking algorithm with an appearance model based on 2D discrete cosine transform (2D-DCT) representations. The DCT has the properties of decorrelation and energy compaction, and is robust against geometry and illumination changes. Hence, it is suitable for appearance modeling and the features of our appearance model are extracted from an optimized low dimensional subspace. In order to adapt to the appearance change caused by environment change or ego motion, we also propose to update the observation appearance model through a nonlinear weighted method. Numerous experiments on some challenging video sequences demonstrated that our algorithm is effective and it considerably outperforms the other methods.

关键词： Discrete cosine transforms Target tracking Visualization Adaptation models Lighting Robustness Feature extraction

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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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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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Solving of interval DC power flow using interval Hull algorithm with preconditioning

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Dianli Xitong Zidonghua/Automation of Electric power systems 2014年第3期38卷 130-136页

作者： Ding, Tao Guo, Qinglai Bo, Rui Gu, Wei Sun, Hongbin Zhang, Boming Department of Electrical Engineering Tsinghua University Beijing 100084 China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing 100084 China Midwest Independent Transmission System Operator Inc. Saint Paul 55108 United States School of Electrical Engineering Southeast University Nanjing 210096 China

With intermittent sources integrated into the power grid, power flows of the power grid are getting stochastic. Considering the uncertainty problem of DC power flow in the high voltage transmission system, this paper recommends an interval Hull algorithm with preconditioning to solve the interval DC power flow. Firstly, the diagonal dominant interval coefficient matrix is formed by preconditioning, then the H-matrix is obtained using the interval Hull algorithm. Different approximation methods are employed for the comparison matrix of H-matrix to improve precision. And the upper and lower bound of the distribution of interval DC power flow is obtained with the iterative method. The interval Hull algorithm and Monte Carlo algorithm are compared in the 9-bus test system, the result of which shows that the uncertainty in grid parameters is the main cause of errors. Furthermore, the Hull algorithm with preconditioning, the interval Hull method, the Krawczyk operator iteration method and the Gauss elimination method are compared in terms of accuracy and computing time on an IEEE 57-bus and an IEEE 118-bus test system, respectively. It is shown that the Hull method with preconditioning has the best accuracy, and the time complexity is far lower than that of the Monte Carlo algorithm. © 2014 state Grid Electric power Research Institute Press.

关键词： Iterative methods

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Expectative Modeling of Wide-area Damping Networked control systems with Long Stochastic Time Delay

Expectative Modeling of Wide-area Damping Networked Control ...

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第25届中国控制与决策会议

作者： Zhang Xinran Lu Chao Han Yingduo State Key Laboratory of Control and Simulation of Power System and Generation Equipments Tsinghua University

ISBN: (纸本)9781467355339

In this paper, the impact of stochastic time delay on wide-area damping networked control systems is analyzed. A disintegrate method of time-delay upon sampling period is approved. Furthermore, the expectative model of networked control systems with long and stochastic time delay, whose variance extent is larger than one sampling period, is theoretically proved and calculated. Finally, the effectiveness of this expectative model is confirmed on the simulation of a power system with 8 generators and 36 nodes.

关键词： Networked control System, Wide Area Damping control, Long Stochastic Time Delay, Expectative Model.

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Interval economic dispatch model with uncertain wind power injection and spatial branch and bound method

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Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering 2014年第22期34卷 3707-3714页

作者： Ding, Tao Guo, Qinglai Bo, Rui Zhang, Liping Sun, Hongbin Wu, Wenchuan Zhang, Boming State Key Lab of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua University Haidian District Beijing100084 China Midwest ISO St. Pau55108 United States Department of Mathematical Science Tsinghua University Haidian District Beijing100084 China

power injection becomes stochastic due to large-scale wind power integration into power grid, which greatly challenges the traditional power grid. If the uncertainty is modelled using the interval number, the solution of economic dispatch model can also be represented as an interval number. To achieve the precise upper and lower bound, two deterministic programming models were deduced: the optimistic solution can be obtained by an optimistic model using linear programming, whereas the pessimistic solution achieved by a pessimistic model is an NP-hard problem, which can be transformed into a bilinear programming by duality theory. Then a linear relaxation technology, spatial branch and bound method were used to obtain the global pessimistic solution. Therefore, the interval bound information can provide the operator with institutive bound information for the future security assessment. Finally, a test system with 15 generators and 300 nodes was studied at different time scales. The result, compared with interior point method and enumeration, shows the effectiveness of proposed method. © 2014 Chinese Society for Electrical Engineering.

关键词： Wind power

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Identification of inactive constraints for SCED model considering uncertain power injection

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Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering 2014年第34期34卷 6050-6057页

作者： Ding, Tao Bo, Rui Guo, Qinglai Sun, Hongbin Huang, Can Li, Fangxing State Key Lab of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing100084 China Midwest ISO St. Paul MN55108 United States Department of Electrical Engineering and Computer Science The University of Tennessee Knoxville TN37996 United States

With the constant expansion of power grid, a large number of security constraints have put tremendous challenges to the online economic dispatch. An efficient tool to eliminate the inactive constraints becomes necessary for security constraints economic dispatch (SCED) in large power systems. In this paper, considering the uncertainty of renewable energy integration, a fast and effective method to identify the inactive security constraints was proposed. Firstly, the definition of uncertain inactive security constraints and a necessary and sufficient condition to identify those were presented respectively. Considering the time-consuming identification, we relaxed the feasible region of original SCED model and utilized greedy algorithm to quickly eliminate part of inactive constraints. Then another necessary and sufficient condition was proposed and verified, where the remaining inactive constraints could be identified. Through the simulation of 24-time periods 9-bus system and 96-time periods IEEE 118-bus system, the speed and effectiveness of proposed method were verified. Moreover, the results can help dispatch operators to locate the transmission lines with the highest congestion risk. © 2014 Chin. Soc. for Elec. Eng.

关键词： Scheduling

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Nanopowder production by gas-embedded electrical explosion of wire

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Chinese Physics B 2013年第4期22卷 350-353页

作者：邹晓兵毛志国王新新江伟华 State Key Laboratory of Control and Simulation of Power System and Generation Equipments Department of Electrical Engineering Tsinghua University Department of Physics and Chemistry College of Science North China University of Technology

A small electrical explosion of wire （EEW） setup for nanopowder production is constructed. It consists of a low inductance capacitor bank of 2 μF–4 μF typically charged to 8 kV–30 kV, a triggered gas switch, and a production chamber housing the exploding wire load and ambient gas. With the EEW device, nanosize powders of titanium oxides, titanium nitrides, copper oxides, and zinc oxides are successfully synthesized. The average particle size of synthesized powders under different experimental conditions is in a range of 20nm–80nm. The pressure of ambient gas or wire vapor can strongly affect the average particle size. The lower the pressure, the smaller the particle size is. For wire material with relatively high resistivity, such as titanium, whose deposited energy Wd is often less than sublimation energy W s due to the flashover breakdown along the wire prematurely ending the Joule heating process, the synthesized particle size of titanium oxides or titanium nitrides increases with overheat coefficient k （k = W d /Ws ） increasing.

关键词： electrical explosion of wire nanosized powders particle size

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