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IEEE PES Asia-Pacific power and Energy Engineering Conference (APPEEC)

作者： Xiaoxian Liu Yong Wang Changwei Song Hanbing Qu Key Laboratory of Power System Intelligent Dispatch and Control Shandong University Jinan China State Grid Jinan Power Supply Company Jinan China

ISBN: (纸本)9781509054190

Micro-grid can absorb the distributed power effectively, reduce loss, and improve power supply reliability. In order to assess micro-grid reliability quantitatively, the random natures of distributed power output are analyzed firstly in this paper. Wind power and photovoltaic Markov model are set up. And the power smoothing of energy storage is considered. Then the corresponding reliability evaluation process was given. And lastly, this paper realizes the micro-grid running states analysis and reliability assessment based on the analytic method. In addition, the new reliability indexes for micro-grid are proposed in the paper. Finally, example proves the efficiency of the above model and method. The results show that distributed power Markov model has a timing sequence and makes the assessment can better reflect the practical operation of micro-grid. It's significant for improving the reliability and economy of micro-grid operation.

关键词： Reliability power system reliability Wind power generation Markov processes Photovoltaic systems Indexes

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Transformer inrush current restraining scheme based on closing voltage amplitude controlling method

Transformer inrush current restraining scheme based on closi...

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IEEE PES Asia-Pacific power and Energy Engineering Conference (APPEEC)

作者： Weixu Wang Wei Cong Yaru Sheng Jing Xiao Jianmei Cao Qingshui Hao Key Laboratory of Power System Intelligent Dispatch and Control Shandong University Jinan China Key Laboratory of Power System Intelligent Dispatch and Control Shandong University Jinan Shandong CN State Grid Shandong Electric Power Corporation Maintenance Company Jinan China State Grid of China Technolgy Coll. Jinan China

ISBN: (纸本)9781509054190

A scheme of restraining transformer inrush current based on control by closing voltage amplitude is proposed based on analyzing the influence factors of transformer inrush current and deriving the mathematical relationship between inrush current and influence factors. In this scheme, in order to making sure that the magnetic flux produced by the transformer no-load closing does not exceed saturated magnetic flux, the voltage amplitude should be controlled by selecting the appropriate curve, thus attaining the goal restraining the transformer inrush current. The control function of voltage amplitude is derived from the magnetic flux inequality and the attenuation law of the transient flux component, and the upper and lower limitation of initial value and slope in the voltage amplitude control function is deduced.

关键词： Surges Magnetic analysis Companies Reliability Switches Magnetic circuits

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An improved approach on static security constrained OPF for AC/DC meshed grids with MMC-HVDC

An improved approach on static security constrained OPF for ...

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IEEE PES Asia-Pacific power and Energy Engineering Conference (APPEEC)

作者： Yi Lin Zhang-sui Lin Liu-qing Qiu Ming-ye Zhang Department of Power Network Research Center State Grid Fujian Power Economic Research Institute Fuzhou China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing China

ISBN: (纸本)9781509054190

This paper presents an optimal power flow model for AC/DC meshed networks with modular multi-level converter based HVDC transmission system (MMC-OPF). The MMC-OPF problem is formulated to minimize the total network loss of the whole AC/DC grids by adjusting generators and converters. In addition, a practical method is proposed to consider N-1 static security constraints with OPF calculation. Case studies of IEEE testing system and a practical network have been carried out. The results demonstrate the effectiveness of the method.

关键词： Indexes Switches

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Security Constrained Economic Dispatch with Dynamic Thermal Rating Technology Integration

Security Constrained Economic Dispatch with Dynamic Thermal ...

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2016 IEEE International Conference on power and Renewable Energy （ICPRE 2016）

作者： Haicheng Zhang Mingtian Du Quangang Zhao Li Xue Zhiqing Wei Qiang Zhang Binzhou Power Supply Company of State Grid Shandong Electric Power Company Key Laboratory of Power System Intelligent Dispatch and Control of Ministry of Education (Shandong University) Shandong Electric Power Dispatching and Control Center

In traditional model for security constrained economic dispatch(SCED) decision, the limit on power transfer capability of overhead transmission line(OTL) is represented by its static thermal rating(STR) which incurs conservative constraints on OTLs' transfer limits which definitely causes conservative decision results. Comparing with STR, dynamic thermal rating(DTR) is an effective technique to improve the ampacity of OTL based on the monitoring of real-time environmental conditions including ambient temperature, solar radiation, wind speed and direction. Aiming to the issue mentioned above, in this paper, a SCED implementation framework is first designed with DTR technology integration, after that, on basis of the historical data gathered by DTR, a forecasting approach for thermal rating is proposed. Predict the environmental conditions along the overhead line using the exponential smoothing method first and then the forecasting of the DTR can be obtained. Then the benefits that delivered by utilizing the forecast thermal rating in SCED is analyzed via case studies. This paper explores an application pattern of DTR technology in SCED. It is capable of enhancing the power system security and economic performances by exploiting the potential transfer capability of OTLs.

关键词： power system overhead line dynamic thermal rating security constrained economic dispatch

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Mutual impedance parameter modeling and accurate location algorithm of angled space crossed transmission lines

Mutual impedance parameter modeling and accurate location al...

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China International Conference on Electricity Distribution, CICED

作者： Ying Zhang Jun Liang Peng Wang Key Laboratory of Power System Intelligent Dispatch and Control Shandong University Jinan China State Grid Dezhou Electric Power Supply Company Dezhou China

ISBN: (纸本)9781467390712

On the account of more and more inevitable scene of angled space crossed transmission line in real project, classical distribution parameter model is no longer applicable, and coupling effect between two lines needs to be reconsidered. This paper popularizes mutual impedance from limited conductor to angled space crossed lines, and analyses the characteristic of mutual impedance coefficient along the line. Based on the segmented nominal-π line model, in which mutual impedance of each section is obtained by Neuman's Integral, the location equation is derived by utilizing the feature that the voltages calculated from two sides are equal at the fault point. simulations in PSCAD compare the differences of fault-location results between in the condition of considering and ignoring coupling effect of space crossed transmission lines. The calculation results demonstrate that the proposed algorithm has higher accuracy, and is not affected by fault types.

关键词： Impedance Conductors power transmission lines Circuit faults Couplings Wires Mathematical model

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Wind Turbine Gearbox fault early warning based on NEST

Wind Turbine Gearbox fault early warning based on NEST

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2016 5th International Conference on Environment, Materials, Chemistry and power Electronics(EMCPE 2016)

作者： Xiao Yan Changliang Liu School of Control and Computer Engineering North China Electric Power University State Key Laboratory Of Alternate Electrical Power System With Renewable Energy Sources(NCEPU)

The condition detection of gearbox is of great significance to improve the operation level and reduce the maintenance cost of the wind turbine. Based on the nonlinear state estimation(NSET) method, the temperature model of the gear box bearing is set up to estimate the states of gear box and the estimated value of the gearbox bearing temperature is obtained. Having obtained the residual error of the estimated value and the actual value of the gearbox bearing temperature, the residual distribution characteristics are analyzed by sliding window error statistics method. The residual distribution characteristic of the model will be changed when the working condition of the gearbox is abnormal, and when the residual mean or standard deviation exceeds the set threshold, the warning is given.

关键词： Fault early warning NEST Grey Relational Analysis Residual characteristic analysis

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Short-Term Wind power Prediction Based on Empirical Mode Decomposition and Extreme Learning Machine

Short-Term Wind Power Prediction Based on Empirical Mode Dec...

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2016 5th International Conference on Environment, Materials, Chemistry and power Electronics(EMCPE 2016)

作者： Jiajia Wu Changliang Liu School of Control and Computer Engineering North China Electric Power University State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources (NCEPU)

Wind power prediction is important for the power system with plenty of wind power. This paper studies the method combined with empirical mode decomposition and extreme learning machine for short-term wind power prediction. The empirical mode decomposition method is utilized to decompose the signal of wind power into sequences with different characteristic scale. The extreme learning machine method is used to model and predict each sequence. Eventually, the prediction results of each sequence are added to obtain the final wind-power prediction results. The simulation result shows that the proposed method in this study improves the prediction accuracy of wind power prediction.

关键词： Wind power power Prediction Empirical Mode Decomposition Extreme Learning Machine

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The Delicate Analysis of Short–Term Load Forecasting

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IOP Conference Series: Materials Science and Engineering 2017年第1期199卷

作者： Changwei Song Yuan Zheng Key Laboratory of Power System Intelligent Dispatch and Control of Ministry of Education Shandong University Jinan China State Grid Jiangxi Electric Power Company Jiujiang Electric Power Supply Company China

This paper proposes a new method for short-term load forecasting based on the similar day method, correlation coefficient and Fast Fourier Transform (FFT) to achieve the precision analysis of load variation from three aspects (typical day, correlation coefficient, spectral analysis) and three dimensions (time dimension, industry dimensions, the main factors influencing the load characteristic such as national policies, regional economic, holidays, electricity and so on). First, the branch algorithm one-class-SVM is adopted to selection the typical day. Second, correlation coefficient method is used to obtain the direction and strength of the linear relationship between two random variables, which can reflect the influence caused by the customer macro policy and the scale of production to the electricity price. Third, Fourier transform residual error correction model is proposed to reflect the nature of load extracting from the residual error. Finally, simulation result indicates the validity and engineering practicability of the proposed method.

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Elastic Modulus Prediction of Three-dimension-4 Directional Braided C_f/SiC Composite Based on Double-scale Model

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Journal of Wuhan University of Technology(Materials Science) 2015年第3期30卷 500-508页

作者：牛序铭 SUN Zhigang KONG Chunyuan 宋迎东 Jiangsu Province Key Laboratory of Aerospace Power System College of Energy and Power Engineering Nanjing University of Aeronautics and Astronautics State Key Laboratory of Mechanics and Control Mechanical Structures College of Energy and Power Nanjing University of Aeronautics & Astronautics

Double-scale model for three-dimension-4 directional（3D-4d） braided C/SiC composites has been proposed to investigate its elastic properties. The double-scale model involves micro-scale that takes fiber/ matrix/porosity in fibers tows into consideration with unit cell which considers the 3D-4d braiding structure. Micro-optical photographs of composites have been taken to study the braided structure. Then a parameterized finite element model that reflects the structure of 3D-4d braided composites is proposed. Double-scale elastic modulus prediction model is developed to predict the elastic properties of 3D-4d braided C/SiC composites. Stiffness and eompliance-averaging method and energy method are adopted to predict the elastic properties of composites. Static-tension experiments have been conducted to investigate the elastic modulus of 3D-4d braided C/SiC composites. Finally, the effect of micro-porosity in fibers tows on the elastic modulus of 3D-4d braided C/SiC composites has been studied. According to the conclusion of this thesis, elastic modulus predicted by energy method and stiffness-averaging method both find good agreement with the experimental values, when taking the micro-porosity in fibers tows into consideration. Differences between the theoretical and experimental values become smaller.

关键词： 3D-4d braided C/SiC composites double-scale model elastic modulus energy methodstiffness and compliance-averaging method porosity ratio

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A dynamic multi-level temporal and spatial coordination method for orderly power utilization based on customer load curtailment cost characteristics

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Dianwang Jishu/power system Technology 2016年第2期40卷 425-432页

作者： Yan, Qingguo Tong, Xing Zhang, Ning Chen, Xiao Yi, Yongxian State Grid Jiangsu Electric Power Company NanjingJiangsu Province210024 China State Key Lab of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing100084 China Jiangsu Electric Power Company Research Institute NanjingJiangsu Province210019 China State Grid Key Laboratory of Electric Power Metrology NanjingJiangsu Province211103 China

When there is power supply shortage or emergency event in power system, orderly power utilization needs to be applied to cut down electricity demand to maintain power supply for important electricity consumers. Current orderly power utilization fails to consider curtailment costs for different regions and customers, and ignores temporal continuity and production regularity of customer, leading to inefficient load curtailment scheduling. This paper proposes a dynamic multi-level temporal and spatial coordinated shortage allocation method considering customer load curtailment costs for orderly power utilization. Load curtailment cost function is established from individual customer level up to provincial electrical grid level. An optimization model is proposed to strategically rearrange customer load profiles across multiple periods. Case studies show that the method efficiently coordinates power shortage in temporal and spatial scale, and significantly brings down economic cost due to curtailment allocation. This model could help promote customer satisfaction level in orderly power utilization. © 2016, power system Technology Press. All right reserved.

关键词： Electric power utilization

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