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A robust interval economic dispatch method accommodating large-scale wind power generation. Part one: Dispatch scheme and mathematical model

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Dianli Xitong Zidonghua/Automation of Electric power systems 2014年第20期38卷 33-39页

作者： Li, Zhigang Wu, Wenchuan 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

Large-scale wind power integration imposes technical challenges to the power system operation and scheduling. Traditional deterministic generation dispatch methods cannot ensure system operation security because they don't incorporate wind power uncertainties appropriately. A new robust dispatch scheme based on the wind power prediction interval is introduced for intra-day active power dispatch, in which wind farms are controlled with the maximum-power-point-tracking strategy mostly. This scheme is featured with flexibility and practicality. In combination with this scheme, a robust interval economic dispatch model is formulated as a robust optimization method and further simplified as a quadratic programming, taking the response of AGC regulation into consideration. Finally, Monte Carlos simulations are conducted on a modified IEEE 24-bus system to compare performance of the proposed approach and the traditional one, and the robustness, reliability and economy of the robust dispatch scheme is verified. © 2014 state Grid Electric power Research Institute Press

关键词： Quadratic programming

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A hierarchical model predictive control method of active power for accommodating large-scale wind power integration

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Dianli Xitong Zidonghua/Automation of Electric power systems 2014年第9期38卷 6-14页

作者： Zhang, Boming Chen, Jianhua Wu, Wenchuan 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

With the ever-increasing size of the power grid and the large-scale integration of stochastic renewable energy, the conventional active power dispatch method has become inapplicable. Therefore, a model predictive control (MPC) based method is proposed to deal with the stochastic characteristic of the grid. Meanwhile, a multi-layer MPC scheme using the industrial large system hierarchical control strategy as a source of reference is adopted to deal with the difficult active power dispatch problem with large-scale wind power integration. The evolutionary process and the corresponding control mechanism of the proposed control scheme are given. ©2014 state Grid Electric power Research Institute Press.

关键词： Model predictive control

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Autonomous-synergetic energy management system family for smart grids: concept, architecture and cases

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Dianli Xitong Zidonghua/Automation of Electric power systems 2014年第9期38卷 1-5and14页

作者： Sun, Hongbin Zhang, Boming Wu, Wenchuan Guo, Qinglai 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

Energy management system (EMS), known as the brain of power grid, utilizes information flow to control energy flow so as to keep power grid operation efficient and secure. Conventionally, the EMS is a centralized one with both information collecting and decision-making centralized. This architecture is facing a serious challenge in mass information collecting and faster decision, especially in smart grid environment. A new concept of distributed autonomy and centralized synergy is proposed and the EMS family covering all sections of smart grids (e.g. source, grid and demand) is concretized. Both commonness and individuality of these EMS family members are discussed. Several new members of EMS family including wind farm EMS, substation EMS and electric vehicle (EV) aggregator EMS are presented, to demonstrate their autonomous characteristic. Interaction among EMS family members is introduced to coordinate the members so as to implement source-grid-demand synergy to form an EMS family network. Several examples of interaction among the EMS family, such as interactions between transmission and distribution, between substations and control center, and between wind farm and EV aggregator, are introduced. ©2014 state Grid Electric power Research Institute Press.

关键词： Energy management systems

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Reactive voltage control of bidirectional-interaction coordination between provincial and district power networks with wind power integration

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Dianli Xitong Zidonghua/Automation of Electric power systems 2014年第24期38卷 48-55页

作者： Wang, Bin Guo, Qinglai Li, Haifeng Sun, Hongbin Tang, Lei Zhang, Boming State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing100084 China Department of Electrical Engineering Tsinghua University Beijing100084 China

An agile and coordinated voltage control method is proposed to deal with the power system reactive power and voltage operation with large scale wind power integration. In the provincial control center, the agile voltage control method with the wind power volatility and the power system N-1 security constraints taken into account is proposed. With this method, by means of the adaptive adjustment of the control period and control model, the wind farm reactive ability will be fully tapped to suppress the influence of wind fluctuations on the bus voltage while sufficient dynamic reactive power regulation margin of traditional generators will be retained. Between provincial and prefectural control centers, the bidirectional interaction based voltage control method is presented to support the voltage at the terminal power network while bypassing the unnecessary discrete device action on the prefectural grid. By coordinated voltage control among the wind farms and substations in the provincial power system, the control abilities of its own wind farms will be made full use of, there will be less capacitor and reactor action times in its own substations and unnecessary reactive power flow. By the bidirectional interaction between provincial and prefectural control centers, the distributed adjustment resources can well be used to support the voltage at the terminal power network and increase the safety and economy of overall operation of the power system. The wind automatic voltage control system is currently in real-time operation in Jiangsu power system. © 2014 state Grid Electric power Research Institute Press.

关键词： Voltage control

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Grid dispatch model and interconnection benefit analysis of concentrating solar power plants with thermal storage

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Dianli Xitong Zidonghua/Automation of Electric power systems 2014年第19期38卷 1-7页

作者： Chen, Runze Sun, Hongbin Li, Zhengshuo Liu, Yibing 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

Nowadays, the concentrating solar power (CSP) plant with thermal storage is a new way to utilize solar power. By making full use of large-capacity CSP devices, the CSP system is able to translate the solar power absorbed. Additionally, the CSP generates power via a steam turbo-generator and has fast regulating performance. The operation behavior of CSP is studied from the viewpoint of power grid, based on which its mathematical model for dispatch is developed. The model describes the power flow inside the CSP with its major operation constraints. Furthermore, the model for power system dispatch considering CSP plants is built based on the security-constrained unit commitment problem. It is shown by simulation that CSP, on the premise of its energy being fully accommodated, may bring about considerable benefits to the power system by reducing the generation cost, increasing renewable energy accommodation and enhancing utilization of transmission lines. © 2014 state Grid Electric power Research Institute Press.

关键词： Concentrated solar power

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Travelling wave based single phase grounding protection for distribution system

Travelling wave based single phase grounding protection for ...

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12th IET International Conference on Developments in power System Protection, DPSP 2014

作者： Dong, Xinzhou Wang, Jun Shi, Shenxing Wang, Bin Dominik, Bak Kirby, Brian Yang, Xia State Key Lab of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing 10084 China Alstom Grid Stafford ST174LX United Kingdom

ISBN: (纸本)9781849198349

It is very difficult to correctly identify single-phase-to-ground fault (SFG) in distribution system with neutral non-effectively grounded (NNG). A novel travelling wave based singlephase-to-ground protection is proposed in the paper. The polarity of initial transient current and voltage travelling waves are used to identify the fault direction, and power frequency voltages are used to distinguish SFG from phaseto- phase fault to ensure the reliability of the protection. In the paper, wavelet transforms and module maxima theory was adopted to represent the polarity of travelling waves effectively and construct protection algorithm,. The analysis and simulation demonstrate that the protection is valid.

关键词： Wavelet transforms

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Failure analysis of fan mill in thermal power plant 68

Failure analysis of fan mill in thermal power plant

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68th Society for Machinery Failure Prevention Technology Conference: Technology Solutions for Affordable Sustainment, MFPT 2014

作者： Liu, Chao Jiang, Dongxiang Chu, Fulei Department of Mechanical Engineering Tsinghua University Beijing100084 China State Key Laboratory of Control and Simulation of Power System and Generation Equipments Department of Thermal Engineering Tsinghua University Beijing100084 China

Fan mill is an important device in thermal plants, which supply coal power to boiler. Crack failures recently occurred in pulverizing wheels of fan mills in a power plant in China. The cracks happens in quite a few pulverizing wheels and they affect the normal operation. To find out the root cause of the cracks, Finite Element Analysis (FEA) of the pulverizing wheel is carried out in this work. The assembly with real dimensions is modelled to calculate the concentrated stress and strain with centrifugal load, driving load, and operational temperature taken into account. Contact effects are included in the finite element model as well as nonlinear material property. Based on the analysis, the crack causes are determined: (i) the initial stress exceeds the yield limit in normal operational condition, resulting low safety coefficient;(ii) the stress increases significantly in the worn pulverizing wheel, where the risk of failure is greatly increased.

关键词： Cracks

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A combined PWM algorithm to eliminate spikes of common mode voltages

A combined PWM algorithm to eliminate spikes of common mode ...

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IEEE Conference and Expo Transportation Electrification Asia-Pacific (ITEC Asia-Pacific)

作者： Fang Liu Zhengming Zhao Ting Lu Shusheng Wei Kai Li Sate Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China

Various pulse width modulation strategies have been proposed to reduce the common mode voltage (CMV) in the variable speed motor drive system. However, unexpected voltage spikes appear as a result of the dead time effect. This paper investigates the principles of those reduced CMV PWM (RCMV PWM) methods mathematically and analyzes the reasons for those voltage spikes theoretically and experimentally. Results suggest that three-dimension active zero state PWM and near state PWM can effectively eliminate the spikes even with the dead time effect taken into consideration. Then a combined algorithm using those two methods is proposed, and it covers the linearity modulation region as large as the conventional space vector PWM. The switchover between those two methods is smooth along with the variation of the modulation index. Experimental results show that no distortion is brought to the modulation wave and verify the validity and feasibility of the proposed combined algorithm.

关键词： Pulse width modulation Vectors Switches Inverters Integrated circuits Induction motors

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Summary of health index theory and application of state maintenance equipment 5

Summary of health index theory and application of state main...

引用

5th International Conference on Reliability of Electrical Products and Electrical Contacts, ICREPEC 2014

作者： Cheng, Lin Manjun, L.I.U. Peng, Feijin Dept. of Elec. Eng. Tsinghua University State Key Lab. of Control and Simulation of Power Systems and Generation Equipments Beijing100084 China Guangdong Power Grid Company Foshan Power Supply Bureau Foshan528010 China

ISBN: (纸本)9789881532329

This paper describes several methods for condition-based maintenance, introduced CBM, RCM development process, the main theoretical logic, techniques and practices. Focuses on the health index based on equipment maintenance strategies, namely CBRM. Focused on the development of narrative context, theoretical foundation, model healthy index. And for its application in power transformers were introduced.

关键词： Condition based maintenance

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Reducing the Impact of Source Internal Resistance by Source Coil in Resonant Wireless power Transfer

Reducing the Impact of Source Internal Resistance by Source ...

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IEEE Energy Conversion Congress and Exposition

作者： Yiming Zhang Ting Lu Zhengming Zhao State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing China

ISBN: (纸本)9781479957774

Wireless power transfer (WPT) is the state-of-the-art research interest. In the WPT system efficiency is an important figure of merit. In order to reduce the impact of the source internal resistance and improve the system efficiency of the conventional two-coil structure, a source coil is added to the two-coil structure, forming a three-coil structure. Both the two-coil structure and the three-coil structure are modeled and analyzed with the circuit theory. The system efficiencies of both structures with optimal loads and a fixed load are deduced. The system efficiency of the three-coil structure is proved to be higher than that of the two-coil structure. An experimental apparatus is implemented and the experimental results match well with the theoretical calculations. The larger the source internal resistance, the more significantly the addition of the source coil improves the system efficiency.

关键词： Coils Wireless communication Resistance Magnetic resonance Integrated circuit modeling Equivalent circuits

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