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International Conference on Renewable power generation, RPG 2015

作者： Li, Kangping Wang, Fei Zhen, Zhao Sun, Yujing Mi, Zengqiang Sun, Hongbin Liu, Chun Wang, Bo Lu, Jing State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University Baoding Hebei Province071003 China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua University Haidian District Beijing100084 China China Electric Power Research Institute Haidian District Beijing100192 China

ISBN: (纸本)9781785610400

Operating Statuses Identification (OSI) can help operators to find fault timely and minimize the loss. So it is of great significance for optimal operation of photovoltaic (PV) plants. The loss quantity of electricity (LQOE) is defined as that should have been generated but actually not, which is caused by inverter fault, PV modules fault, dust stratification or combinations of them. Firstly, mathematical models of PV cells are proposed to figure out the LQOE of each PV module. Secondly, after analysing the relation between LQOE and operating statuses, an index set of LQOE describing the distinction of different operating statuses are defined including four statistical feature parameters and a user-defined index. Thirdly, Support Vector Classification models for OSI (OSI-SVC) are built with input features extracted from the index set. Lastly, simulations are carried out to verify the effectiveness and evaluate the performance of the OSI-SVC models. The results indicated that the operating statuses can be effectively recognized by the proposed model.

关键词： Support vector machines

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Cloud identification model for sky images based on Otsu

Cloud identification model for sky images based on Otsu

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International Conference on Renewable power generation, RPG 2015

作者： Li, Hongping Wang, Fei Ren, Hui Sun, Hongbin Liu, Chun Wang, Bo Lu, Jing Zhen, Zhao State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University Baoding Hebei Province071003 China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua University Haidian District Beijing100084 China China Electric Power Research Institute Haidian District Beijing100192 China

ISBN: (纸本)9781785610400

Irradiance changes caused by clouds movement are the mam factors, which lead to mutation of photovoltaic power. In order to increase the accuracy of the ultra-short-term photovoltaic power prediction, based on of clouds images, the cloud identification for sky images is one of the primary aspects for improving photovoltaic power accuracy. A cloud identification model for sky images is established based on Otsu. Firstly, a series of sky images are collected by Total Sky Imager (TSI) with the regions of clouds and sky are distinguished. Secondly, the color features (based on RGB values) of pixels in sample images and the spectral and texture features of the whole image are extracted;Finally, we established a cloud identification model for sky images based on Otsu according to the clouds' and sky areas' division and the general characteristics featured by pixels and images. The simulated results show that the model in this paper can identify the clouds in a sky images effectively.

关键词： Pixels

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Stability analysis of wide-area damping control system with stochastic communication time delay

Stability analysis of wide-area damping control system with ...

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Innovative Smart Grid Technologies (ISGT)

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

ISBN: (纸本)9781479917860

Stochastic time delay is a new challenge brought out by communication network in wide-area damping control system. Uncertainty introduced by stochastic time delay increases the difficulty of modeling and stability analysis. In this paper, a new approach of stability analysis through expectation model is proposed to solve the problem of uncertainty in wide-area controlled power systems considering the effect of stochastic time delay. In the proposed method, expectation model considering detailed stochastic time delay distribution is derived to accurately model the impact of communication network on wide-area control performance. Then, through matrix transformation of expectation model, eigenvalue of wide-area damping control system considering time delay can be calculated, which can be used for analyzing the system stability. Finally, the effectiveness of this method is verified through the simulation of a power system with 8 generators and 36 nodes with different types of time delay distribution.

关键词： Delay effects power system stability Stability analysis Eigenvalues and eigenfunctions Stochastic processes Damping Analytical models

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Virtual synchronous control of grid-connected DFIG-based wind turbines

Virtual synchronous control of grid-connected DFIG-based win...

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Annual IEEE Conference on Applied power Electronics Conference and Exposition (APEC)

作者： Yangyang Zhao Jianyun Chai Xudong Sun State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing China

This paper proposes a virtual synchronous control strategy for Doubly-Fed Induction Generator (DFIG)-based wind turbines. On the basis of the proposed excitation control model orientated by rotor flux, and the P-f, Q-V droop control models which emulate the governor and exciter of synchronous machine, this paper established the basic virtual synchronous control structure for DFIG. This control strategy can provide DFIGbased wind turbines with intrinsic regulation ability of frequency and voltage without using the phase-locked loop (PLL) of the grid. Considering the power limitation under certain wind speed, the proposed adaptive droop control method realized the maximum power point tracking (MPPT) of wind turbines in steady state. simulation results demonstrate the feasibility and effectiveness of the presented virtual synchronous control for grid-connected DFIG. This control strategy can not only provide the possibility of unifying the grid-connected wind turbines as the standard synchronous power, but also decrease the negative effect on the grid frequency and voltage with high penetration of wind energy.

关键词： Wind turbines Rotors Frequency control Frequency synchronization Mathematical model Voltage control Steady-state

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Analysis of Ant Colony Algorithm for Finding the Optimal Circuitous Route in the Communication Network of power system

Analysis of Ant Colony Algorithm for Finding the Optimal Cir...

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International Conference on Electric Utility Deregulation and Restructuring and power Technologies

作者： Xin Chen Zhiqian Bo Xinzhou Dong Shenxing Shi State Key Laboratory of Control and Simulation of Power System and Generation Equipments Tsinghua University Beijing China

ISBN: (纸本)9781467371070

The communication network of power system is often damaged after a disaster. To solve this problem, this paper uses ant colony algorithm to find the optimal circuitous route. simulation results show that the method is fast, which can accelerate the recovery of the communication network. Besides, this paper does some research on the dead end problem, and analyses relationship between degree of adjacency and ratio of coming to a dead end. The result shows that the efficiency of ant colony algorithm can be improved only if it tries to avoid coming to dead ends.

关键词： ant colony algorithm circuitous route degree of adjacency dead end

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Wind Turbine Fault Diagnosis system Based on A Fuzzy Expert system

Wind Turbine Fault Diagnosis System Based on A Fuzzy Expert ...

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2015 International power,Electronics and Materials Engineering Conference(IPEMEC 2015)

作者： Wenguang Yang Dongxiang Jiang State Key Laboratory of Control and Simulation of Power System and Generation Equipments Department of Thermal EngineeringTsinghua University

ISBN: (纸本)9781510806474

A fuzzy expert system which can simultaneously support many kinds of rules including fuzzy production rule,fault tree and decision tree in a unified framework are *** rete algorithm is adopted to speed up the fuzzy reasoning chain.A wind turbine diagnosis expert system is developed based on the fuzzy expert *** data is employed to verify the feasibility of the inference engine,and the results show that with proper knowledge imported the misdiagnosis rate is low,the inference process can be exported and the match degree of the health rule can be used as a health state indicator.

关键词： Wind turbine Fault diagnosis system Fuzzy expert system Fuzzy Rete algorithm

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Fault Line Identification of Single Line to Ground Fault for Non-Effectively Grounded Distribution Networks with Double-Circuit Lines

Fault Line Identification of Single Line to Ground Fault for...

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IEEE power and Energy Society General Meeting

作者： Bo Jiang Xinzhou Dong Shenxing Shi Bin Wang State Key Lab. Of Control and Simulation of Power System and Generation Equipment Dept. of Electrical Engineering Tsinghua University Beijing 100084 China

ISBN: (纸本)9781467380416

Single Line to Ground (SLG) faults in non-effectively grounded networks are difficult to detect. Immune to neutral point grounding type, load conditions and system operation conditions, traveling-wave based method is an effective fault line identification method. However, due to the strong coupling between the double-circuit lines, the wavefront magnitude of them are the same, and the polarity of them are opposite. Thus, the mal-identification will be resulted under such condition. This paper analyzed the traveling wave characteristics of double-circuit lines, and proposed an improved fault line identification method based on the initial process of zero sequence currents and voltage traveling waves. Tests show that, the proposed method has high effectiveness in fault line identification of double-circuit lines in distribution networks.

关键词： distribution networks double-circuit fault line identification non-effectively grounded traveling wave Double circuit power grids line down Earth faults traveling waves single line

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Dynamic Response of Rubbing Happening in a Flexible Rotor-Bearing system

Dynamic Response of Rubbing Happening in a Flexible Rotor-Be...

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2015 International Conference on Electrical, Automation and Mechanical Engineering(EAME 2015)

作者： J.M.Chen D.X.Jiang T.T.Deng J.S.Wang J.L.Zhong S.B.Wang State Key Laboratory of Control and Simulation of Power System and Generation Equipments Department of Thermal Engineering Tsinghua University Guizhou Electric Power Research Institute

ISBN: (纸本)9781510806528

To reduce the steam loss and raise the efficiency of the steam turbine,the vapour seals are applied in the inner cylinder of the steam *** small gap may easily results in the rubbing happening in the inner ***,the rotor is a flexible *** this paper,dynamic response of rubbing happening in a flexible rotor-bearing system was studied.A simplified flexible rotor-bearing system was constructed,whose rotating speed was between the 1st and 2nd critical rotating *** effect was considered in the analysis,*** rubbing introduce heat and result in the thermally induced *** transient thermal bow was treated as a pair of moments functioning on the shaft segment where rubbing *** shows the amplitude and phase of vibration would be stable after a long *** severity of rubbing affect the stabilization time,which could be regarded as a diagnostic feature to identify the severity of rub happening in a flexible rotor-bearing system.

关键词： thermally induced vibration equivalent thermal moment stabilization time rubbing flexible rotor-bearing system

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Ambient signal based load model parameter identification using optimization method

Ambient signal based load model parameter identification usi...

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IEEE General Meeting power& Energy Society

作者： Xinran Zhang Chao Lu Yingduo Han Songtai Yu Jifeng Wang He Huang Yinsheng Su State Key Laboratory of Control and Simulation of Power System and Generation Equipments Tsinghua University Beijing China China Southern Power Grid Guangzhou China

Load modelling is a crucial part in modelling a power system. The complex, nonlinear and stochastic characteristics of power load increase the difficulty of modelling. In this paper, a new approach of ambient signal based load model parameter identification method is proposed to solve this problem. With the proposed method, load model parameter can be identified in any time regardless of the existence of fault. First, Z+M model is simplified to reduce the number of parameters to be identified. Then, parameters of Z+M model are identified with an optimization method, the objective function of which is calculated from WAMS measured power and voltage data. An iterative process is proposed to solve the problem of initial value sensitivity in optimization problems. Finally, the effectiveness of this identification method is validated through the simulation results on WSCC three machines nine nodes system under different operation situation including both small disturbance and large disturbance.

关键词： Load modeling Optimization Integrated circuit modeling Parameter estimation Data models Reactive power power measurement

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A real-time wind power control method for power systems with high wind power penetration and its implementation

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Dianli Xitong Zidonghua/Automation of Electric power systems 2015年第21期39卷 23-29页

作者： Wang, Bin Sun, Yong Wu, Wenchuan Zheng, Taiyi Zhang, Boming State Key Laboratory of Control and Simulation of Power System and Generation Equipments Tsinghua University Beijing100084 China Department of Electrical Engineering Tsinghua University Beijing100084 China State Grid Jilin Electric Power Supply Company Changchun130021 China

A real-time wind power control method is proposed to accommodate the severe fluctuation of wind power, which can be used in power systems with high wind power penetration. The maximum allowable wind power generation is estimated online according to the automatic generation control (AGC) downward spinning reserve and the tie-line power deviation. Considering the different priorities for wind farms and the transmission security constraints, different control strategies, such as corrective control to eliminate the transmission congestion, optimal dispatch considering the trade-off between minimum curtailment of wind power and the fairness among wind farms, are integrated in the proposed method. The numerical simulation on the test system and the results of field operation in a provincial power grid show that the method is efficient and practical. © 2015 Automation of Electric power systems Press.

关键词： Wind farm

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