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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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Automatic voltage control of wind farms based on model predictive control theory

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Dianli Xitong Zidonghua/Automation of Electric power systems 2015年第7期39卷 59-67页

作者： Xu, Fengda Guo, Qinglai Sun, Hongbin Lan, Haibo Liu, Haitao Liu, Xiaomin Department of Electrical Engineering Tsinghua University Beijing100084 China State Key Laboratory of Control and Simulation of Power System and Generation Equipments Tsinghua University Beijing100084 China State Grid North Hebei Grid Company Limited Beijing100053 China

Voltage fluctuations occur frequently in wind farms as a result of wind power perturbation, while reactive power control of various devices is always uncoordinated and often has a time lag when the system operates in the traditional control mode that only uses the current data for decision-making. In this case, a method for coordinated control of the reactive power of wind turbine generators (WTGs) and static var generators is proposed based on model predictive control (MPC). Unlike the traditional voltage control method, the control method proposed has the realization of optimization of the voltage control curve and the dynamic process of reactive power regulation in the future window of time as its objective. An auto regression moving average (ARMA) model is used to predict the active power of WTGs while the reactive power of WTGs and the SVG is forecasted using a first-order inertia link and a proportional integral (PI) link, respectively. Voltages in the wind farm are solved with the help of a sensitivity matrix. Thus an optimization model is developed for both the minimization of PCC voltage deviation and the maximization of SVG reactive power reservation in a future window of time. The optimizing model is solved using CPLEX tools with the dual simplex algorithm. In order to test the performance of the MPC controller, multiple cases with different wind circumstances are simulated on a DIgSILENT platform. simulation results reveal that by predicting the states of various instruments in wind farms during a period of time in the future, the proposed control method is able to rationally arrange fast/slow reactive power to respond to predictable changes of the system in advance and keep voltage stable. ©2015 state Grid Electric power Research Institute Press

关键词： Reactive power

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Secondary voltage control considering rapid dynamic reactive power compensation

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Dianli Xitong Zidonghua/Automation of Electric power systems 2015年第2期39卷 53-60页

作者： Wang, Xuran Guo, Qinglai Sun, Hongbin Wang, Bin Zhang, Mingye Zhang, Boming 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

This paper presents a secondary voltage control system considering rapid dynamic var compensators, such as static var compensator/static synchronous compensator (SVC/STATCOM). In order to take full advantage of the rapid adjustment feature of SVC/STATCOM in static voltage control and transient voltage stability, two independent control stages are dealt with. In the first stage, SVC/STATCOM and conventional var compensators are incorporated in the coordinate secondary voltage control model to bring the rapid adjustment feature of SVC/STATCOM into full play. In the second stage, a quadratic programming model is designed to do the optimal control of the dynamic reactive power reserves. The reactive power compensation of the slow dynamic var compensators is substituted for that of SVC/STATCOM, and the dynamic reactive power reserves level is improved. Through coordination between sequence and space, all kinds of reactive power compensators are made full use of in the secondary voltage control and transient voltage stability prevention control. Nordic system test results show that the system can greatly improve the response speed of traditional secondary voltage control while avoiding the conflict between SVC/STATCOM and the traditional reactive power compensators. At the same time, the system is able to carry out effective preventive control of transient voltage stability and improve the recovery effect of system voltage after the disturbance. ©, 2015 state Grid Electric power Research Institute Press.

关键词： Reactive power

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Evaluation method for node importance based on service in electric power communication network

Evaluation method for node importance based on service in el...

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作者： Zeng, Ying Li, Xingnan Deng, Boren Wu, Runze Zou, Yingjie Luo, Yun Power Dispatch and Control Center of Guangdong Grid GuangzhouGuangdong China State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University Beijing China Sichuan Enrising Information Technology Co. Ltd ChengduSichuan China

ISBN: (纸本)9781138028302

A new evaluation method for node importance is proposed with the combination of the node contraction method in complex networks and the functional analysis of the importance evaluation for power service in practical operation. The definite application of this algorithm features the particularity of the power industry. Firstly, we classify the power services, then relate the importance degree of power service to the edge weight which is used to calculate the node weight and its importance. Finally, the simulation example, we have testified corresponds ultimately to the practical situation. © 2015 Taylor & Francis Group, London.

关键词： Complex networks

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Research on perception of power system state based on WAMS

Research on perception of power system state based on WAMS

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Innovative Smart Grid Technologies (ISGT)

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

ISBN: (纸本)9781479917860

The development of Smart Grid requires more accurate and fast for perception, assessment and control of power system state. Widely installed phasor measurement units (PMU) and mass PMU measurements provide a good foundation for this requirement, because PMU can directly measure bus voltage phasors at the rate of tens of milliseconds. Thus, the number of PMU installed in the power grid and the reliability and accuracy of PMU measurements are of great importance, which directly affect the feasibility and reliability of state perception. Actually, PMU measurements may contain bad data and the accuracy of phase measurements is not high enough. Estimation method is an effective way to deal with data contaminated by noise and bias. In this paper, we proposes the complex number weighted least squares (CWLS) estimation algorithm to process PMU measurements directly in the complex domain to obtain more accurate system state. Phasor error characteristics in the complex domain are analyzed depth which shows the proposed algorithm is robust to phase error. Meanwhile, an effective bad data identification method is proposed. Test results demonstrate the performance of the CWLS algorithm from the perspectives of computional efficiency, estimation quality and adaptability to inconsistent measurment errors, the robustness of the CWLS algorithm and the effectiveness of the proposed bad data identification method is also shown in the tests.

关键词： Phasor measurement units Estimation Measurement errors Voltage measurement power systems Phase measurement Algorithm design and analysis

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Pretreatment of coal gasification wastewater by adsorption using activated carbons and activated coke

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Colloids and Surfaces A: Physicochemical and Engineering Aspects 2015年 482卷 177-183页

作者： Peng Li Nuerla Ailijiang Xiaoxin Cao Ting Lei Peng Liang Xiaoyuan Zhang Xia Huang Jilin Teng State Key Joint Laboratory of Environment Simulation and Pollution Control School of Environment Tsinghua University Beijing 100084 China State Grid Electric Power Research Institute Beijing 100067 China

Powdered (below 125 μm) activated carbons made by wood (WAC) and coal (CAC) and activated coke (AC), whose BET surface areas were 551, 335 and 484 m 2 /g, respectively, were studied to adsorb organic pollutants from coal gasification wastewater (CGWW). This study initially focused on the equilibrium sorption isotherms of adsorbents for the removal of chemical oxygen demand (COD) from CGWW. Molecular weight (MW) distribution and fluorescence excitation emission matrix (FEEM) were used to determine the difference of CGWW quality. Water qualities of CGWW before and after adsorption by adsorbents were also investigated. The isotherm results showed that Langmuir model fit the adsorption isotherms of activated carbons, while Freundlich model was better for that of AC. CAC and AC had a higher adsorption capacity under lower and higher COD concentration, respectively. It was also found from MW distribution and FEEM results that AC had a prior adsorption to high MW aromatic, refractory compounds in CGWW, which is good for the following biological treatment and suitable for pretreatment. This was because that the mesopores percentage of AC was 63%, which was higher than WAC and CAC.

关键词： Coal gasification wastewater Adsorption Pretreatment Activated coke Activated carbons

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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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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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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： Yujing Sun Fei Wang Zengqiang Mi Hongbin Sun Chun Liu Bo Wang Jing Lu Zhao Zhen Kangping Li State Key Laboratory of Alternate Electrical Power System With Renewable Energy Sources North China Electric Power University Baoding Hebei China State Key Laboratory of Alternate Electrical Power System With Renewable Energy Sources Tsinghua University Beijing Haidian China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing Haidian China China Electric PowerResearch Institute Beijing Haidian China

ISBN: (纸本)9781510821415

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 analy%ed 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： impact factor module temperature photovoltaic power forecasting step-wise prediction support vector machine

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

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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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