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Method of coordination among strongly coupled power plants for automatic voltage control

Dianli Xitong Zidonghua/Automation of Electric power systems 2015年第12期39卷 165-171页

作者： Wang, Bin Guo, Qinglai Sun, Hongbin Tang, Lei Zhang, Boming Tian, Junjie 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 Dispatching and Communication Center of State Grid Shanxi Electric Power Corporation Taiyuan030001 China

To solve the problem of reactive power non-coordination among strongly coupled plants, a coordinating method for strongly coupled plants for automatic voltage control (AVC) is proposed. The coupling coefficient among plants is introduced, and the plant coordinating group is generated as the coordinating unit. The reactive power unbalanced index among strongly coupled plants is defined. And the current operation state of power grid is determined. In the event the pilot bus voltage is not controlled in place, the control strategy of voltage regulation and reactive power tracking control is adopted so that the pilot bus voltage will be enabled to guarantee that the reactive power unbalanced index between strongly coupled plants will meet the control requirement while tracking optimal settings. If the pilot bus voltage is already in place, reactive correction control based on the objective of plant-to-plant coordination will be carried out to reduce the deviation in reactive load while ensuring that the pilot bus voltage is maintained within the range of control dead zone. Reactive regulating commands will be added to the traditional voltage regulating commands to suppress possible irrational reactive power distribution or reactive fluctuation between strongly coupled plants. Application of the proposed method in a number of regional and provincial grids in China shows that the proposed method is able to reduce irrational reactive power distribution between strongly coupled plants. © 2015 state Grid Electric power Research Institute Press.

关键词： Reactive power

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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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Transmission expansion planning modelfacilitating low-carbon power sources' development

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Dianwang Jishu/power System Technology 2015年第10期39卷 2725-2730页

作者： Du, Ershun Sun, Yanlong Zhang, Ning Chen, Songsong He, Guixiong Kang, Chongqing State Key Lab of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing100084 China China Electric Power Research Institute Haidian District Beijing100192 China

power planning oriented to low-carbon can relief 'carbon lock' effect and facilitate to achieve low-carbon power system. For tapping low-carbon potential of power grid, this paper comprehensively analyzes corresponding low-carbon elements and proposes a novel transmission planning model for promoting low-carbon power sources' development. These analyses include facilitation of integration and accommodation of renewable power, life cycle carbon emission process and reduction of grid loss. Based on multi-scenario technique, the proposed model minutely simulates system operation process considering both typical and extreme operation constrains. Through inequality separation and piecewise linearization, original model is converted into a large scale mixed integer linear programming (MILP) model. Case study of Jiangsu provincial grid verifies validity of the proposed model. ©, 2015, power System Technology Press. All right reserved.

关键词： Life cycle

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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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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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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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Smart substation advanced application software adapted for two-level distributed smart dispatch and control

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Dianli Xitong Zidonghua/Automation of Electric power systems 2015年第1期39卷 233-240页

作者： Sun, Hongbin Mu, Jianan Sheng, Tongtian Li, Qingxin Wang, Jing Wang, Bin Wang, Xuran Ji, Guoqiang Wu, Wenchuan Guo, Qinglai Li, Yalou Wang, Dexing 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 East China Electric Power Dispatching and Control Sub-Center of State Grid Shanghai200120 China

The development of smart grid has posed a challenge to the traditional centralized dispatch mode. The basic contradiction between distributed autonomy and centralized coordination is reexamined, and an architecture of smart substation advanced application software system is proposed, including such advanced applications as modeling, state estimation, intelligent alarming, voltage stability assessment and control, automatic voltage control, risk assessment modeling, etc. This facilitates a change from centralized dispatch and control mode to a more reliable, agile substation-control center two-level distributed smart dispatch and control mode. The features, functions and realization of the proposed advanced application software are described, some field engineering application cases demonstrated, and certain practical aspects of implementation discussed. Finally, the prospect for future development of the smart substation advanced application software is displayed.

关键词： state estimation

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Analysis on Lightning Current and Position During Shielding Failure of High Voltage AC Transmission Lines

Analysis on Lightning Current and Position During Shielding ...

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2015 International Conference on simulation, Modelling and Mathematical Statistics(SMMS 2015)

作者： Shan-qiang GU Zhan-qing YU Xuan ZHOU Ze-zhong WANG Tong ZHU Bi-wu YAN Jin-liang HE Rong ZENG Chi-jie ZHUANG Electric Power Research Institute China State Grid LTD State Key Lab of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University

Shielding failure of lightning is the key problem for safe operation of transmission lines. Compare to Electro-geometry Method, Leader Progress Method more suitable for lightning protection analysis because the physical model is used instead of empirical formula. The relationship between amplitude of lightning current and other parameters, such as wires position, ground tilt angle, was analyzed.

关键词： Lightning stroke Shielding failure Transmission Line Leader progress

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Short-term prediction model of module temperature for photovoltaic power forcasting based on support vector machine

Short-term prediction model of module temperature for photov...

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International Conference on Renewable power generation, RPG 2015

作者： Sun, Yujing Wang, Fei Mi, Zengaiang Sun, Hongbin Liu, Chun Wang, Bo Lu, Jing Zhen, Zhao Li, Kangping 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

To improve the prediction accuracy of photovoltaic (PV) power generation, the temperature of PV modules and its prediction is very important. A short-term step-wise temperature prediction model for PV module based on Support Vector Machine (SVM) is proposed in this paper. Firstly, the primary impact factors of PV module temperature are determined in terms of the PV module physical characteristics and the correlation coefficient between each factor and module temperature. Secondly, two kinds of prediction models, direct and step-wise models, are built to predict module temperature respectively. For direct model, the prediction model is based on SVM using the historical data. For step-wise one, the prediction models of the primary impact factors are built at the first step and then the mapping models between module temperature and the impact factors are established. In the end, the deviations of two different kinds of prediction models are analyzed and discussed based on actual operation data. The results indicate that the stepwise prediction model has better accuracy than the direct prediction model if other things are equal.

关键词： Forecasting

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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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