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Effects of manganese dioxide additives on the electrical characteristics of Al-doped ZnO varistors

Science China(Technological Sciences) 2011年第8期54卷 2204-2208页

作者： LONG WangCheng HU Jun HE JinLiang LIU Jun ZENG Rong State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing 100084 China

The effects of manganese dioxide (MnO 2 ) additives on the electrical characteristics of the Al-doped ZnO varistors are investigated. The leakage current densities of the samples decrease first and then increase again with the increase of the amount of MnO 2 additives. Correspondingly, the nonlinear coefficients of the samples keep on increasing and then decrease. In addition, the donor densities increase monotonously with the amount of the doped MnO 2 increasing. The effects of MnO 2 additives on the electrical characteristics of the samples are different from the conclusion of previous literatures. The reasons of the distinct effects are supposed to be related with the donor and interface state densities of the samples.

关键词： ZnO varistots manganese dioxide electrical characteristics low residual voltage ratio simulation

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Stochastic processes in renewable power systems: From frequency domain to time domain

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Science China(Technological Sciences) 2019年第12期62卷 2093-2103页

作者： SONG YongHua CHEN XiaoShuang LIN Jin LIU Feng QIU YiWei Department of Electrical and Computer Engineering University of MacaoMacaoChina State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department of Electrical EngineeringTsinghua UniversityBeijing 100084China

With the increasing penetration of renewable energy resources(RESs), the uncertainties of volatile renewable generations significantly affect the power system operation. Such uncertainties are usually modeled as stochastic variables obeying specific distributions by neglecting the temporal correlations. Conventional approaches to hedge the negative effects caused by such uncertainties are thus hard to pursue a trade-off between computation efficiency and optimality. As an alternative, the theory of stochastic process can naturally model temporal correlation in closed forms. Attracted by this feature, our research group has been conducting thorough researches in the past decade to introduce stochastic processes within renewable power systems. This paper summarizes our works from the perspective of both the frequency domain and the time domain, provides the tools for the analysis and control of power systems under a unified framework of stochastic processes, and discusses the underlying reasons that stochastic process-based approaches can perform better than conventional approaches on both computational efficiency and optimality. These work may shed a new light on the research of analysis, control and operation of renewable power ***, this paper outlooks the theoretic developments of stochastic processes in future’s renewable power systems.

关键词： renewable energy resources renewable power systems stochastic processes frequency domain time domain

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Electron relaxation properties of Ar magnetron plasmas

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Plasma Science and Technology 2018年第3期20卷 87-94页

作者： Xinjing CAI Xinxin WANG Xiaobing ZOU Department of Electrical Engineering Northeast Electric Power UniversityJilin 132012People's Republic of China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Tsinghua UniversityBeijing 100084People's Republic of China

An understanding of electron relaxation properties in plasmas is of importance in the application of *** improved multi-term approximation of the Boltzmann equation is employed to study electron transport and relaxation properties in ***,inelastic and nonconservative collisions between electrons and neutral particles are *** expressions for the transport coefficients are obtained using the expansion coefficients and the collision operator *** solutions of the matrix equations for the expansion coefficients are also *** calculations of the Reid model are presented to demonstrate the accuracy of the improved multi-term *** is shown that the twoterm approximation is generally not accurate enough and the magnetic fields can reduce the anisotropy of the velocity distribution *** electron relaxation properties of Ar plasmas in magnetrons for various magnetic fields are *** is demonstrated that the energy parameters change more slowly than the momentum parameters.

关键词： electron transport electron relaxation Boltzmann equation multi-term approximation

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Real-time electromagnetic transient simulation algorithm for integrated power systems based on network level and component level parallelism

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Science China(Technological Sciences) 2012年第11期55卷 3232-3241页

作者： CHEN LaiJun CHEN Ying MEI ShengWei State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments(Department of Electrical Engineering Tsinghua University)Beijing 100084China

The analysis and simulation of power system are becoming more and more challenging as the complexity of system topology and components has been increased. In this paper, a hybrid parallel algorithm is proposed for the real-time electromagnetic transient simulation （EMTS） of integrated power systems containing multiphase machines. The proposed algorithm is com- posed of a novel network partition method called component level parallelization and the Multi-Area Thevenin Equivalent （MATE） method, which extends the flexibility of the network partition in parallel simulation. Moreover, several methods are developed to enhance the efficiency of the communication and computation. power systems with up to 410 single-phase elec- trical nodes and 336 switches are simulated in a time step of 50 ~ts to validate the proposed algorithm.

关键词： EMTP multiphase machine network partition parallel computing power system real-time simulation

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On Dispatching power systems with Significant Wind generation Using Disturbance Feedbacks

On Dispatching Power Systems with Significant Wind Generatio...

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第三十二届中国控制会议

作者： WEI Wei MEI Shengwei LIU Feng State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department of Electrical EngineeringTsinghua University

ISBN: (纸本)9781479900305

With the rapid development of renewable energies,especially wind power,how to manage unexpected generation variations economically and reliably in dispatch has become crucial for modern power *** address this issue,this paper presents an affine disturbance feedback robust dispatch(ADF-RD) methodology for power systems with large scale wind power integration in the framework of adjustable robust optimization(ARO).This methodology divides the dispatching process into pre-dispatch and ***-dispatch decision immunizes against all possible realizations of uncertainties in a set,while re-dispatch which can be regarded as a feedback will be adaptively adjusted using an affine function with respect to the realized uncertainty in real *** ADF-RD methodology is applied to an hourly ahead dispatch(HAD) *** effectiveness and efficiency of the proposed ADF-RD methodology are demonstrated by numerical experiments carried on a five-bus system.

关键词： Adjustable robust optimization affine disturbance feedback power system dispatch uncertainty wind power

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Effect of Multiple Models of Closed-loop Transfer Functions on Inter-harmonic Oscillation Characteristics of Grid-connected PMSG

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CSEE Journal of power and Energy systems 2024年第5期10卷 1955-1964页

作者： Jingyi Li Jianjun Yang Xiaorong Xie Haozhi Li Ke Wang Zhaohui Shi Key Laboratory of Far-shore Wind Power Technology of Zhejiang Province Huadong Engineering Corporation LimitedPower ChinaHangzhou 310014China. State Key Lab of Control and Simulation of Power Systems and Generation Equipment(Dept.of Electrical Engineering Tsinghua University)Beijing 100084China.

Establishing a suitable closed-loop transfer function model for the grid-connected PMSG system is the key basis in performing inter-harmonic characteristics *** closed-loop transfer functions can be constructed when different components of the converter controller are taken into ***,the effect of different components of the converter controller on inter-harmonic stability analysis is not *** this paper,the complete transfer function,considering different loops,is first *** on the complete closed-loop transfer function,the DC-link,PLL and voltage forward-feed are removed step by step to derive different closed-loop transfer *** inter-harmonic related poles of different closed-loop transfer functions are further calculated to analyze the effect of closedloop transfer functions on inter-harmonic characteristics ***,by performing time domain simulation,the correctness of the theoretical analysis results is *** results show that under the conditions of a weak AC system,each loop of the converter control system will reduce the stability of the interharmonic in the sub-synchronous frequency range and influence the inter-harmonic oscillation *** transfer function needs to consider the influence of each loop to accurately calculate the inter-harmonic stability of the system.

关键词： Closed-loop transfer function converter controller inter-harmonic characteristics PMSG

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Research focuses and advance technologies of smart grid in recent years

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Chinese Science Bulletin 2012年第22期57卷 2879-2886页

作者： MEI ShengWei CHEN LaiJun State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Department of'Electrical EngineeringTsinghuaUniversityBeijing 100084China

The smart grid is attracting more and more attention in electrical engineering for its promising ***,huge challenges also exist in the implementations of the smart grid,such as high penetration of renewable energy resources,low carbon electricity and cyber-physical security,*** this paper,the latest progress of some research focuses and advance technologies in the development of smart grid is reviewed.

关键词：电网智能技术网络物理安全可再生能源电气工程渗透力

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A Fuzzy Hierarchical Strategy for Improving Frequency Regulation of Battery Energy Storage System

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Journal of Modern power systems and Clean Energy 2021年第4期9卷 689-698页

作者： Kaifeng Wang Ying Qiao Lirong Xie Jiaming Li Zongxiang Lu Huan Yang School of Electrical Engineering Xinjiang UniversityUrumqiChina State Key Laboratory of Control and Simulation of Power Systems Generation Equipments of Electrical Engineering Tsinghua UniversityBeijingChina

Battery energy storage systems(BESSs)can provide instantaneous support for frequency regulation(FR)because of their fast response ***,purely pursuing a better FR effect calls for continually rapid cycles of BESSs,which shortens their lifetime and deteriorates the operational *** coordinate the lifespan savings and the FR effect,this paper presents a control strategy for the FR of BESSs based on fuzzy logic and hierarchical *** fuzzy logic controller improves the effect of FR by adjusting the charging/discharging power of the BESS with a higher response speed and precision based on the area control error(ACE)signal and the change rate of ACE in a non-linear *** controllers effectively reduce the life loss by optimizing the depth of discharge,which ensures that the state of charge(SOC)of BESS is always in the optimal operating range,and the total FR cost is the lowest at this *** proposed method can achieve the optimal balance between ACE reduction and operational economy of *** effectiveness of the proposed strategy is verified in a two-area power system.

关键词： Battery energy storage system(BESS) frequency regulation(FR) coordinated control strategy optimal depth of discharge charging/discharging threshold

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A fast algorithm for manipulation control process of distribution system planning solution

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Journal of Modern power systems and Clean Energy 2019年第6期7卷 1547-1558页

作者： Lin CHENG Yuxiang WAN Liting TIAN Fang ZHANG State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical EngineeringTsinghua UniversityBeijingChina School of Electrical Engineering Beijing Jiaotong UniversityBeijingChina

Better flexibility and controllability have been introduced into distribution system with the development of new loads and *** a consequence,the connotations and tools for evaluating the planning solution need to be further *** paper proposes a fast algorithm to quantify steady-state voltages and load profiles in distribution system by simulating the manipulation control process of controllable resources,taking the efficiency and ease of use into *** this method,a complex distribution system is decoupled into several simple parts according to the ports of the DC ***,to achieve the qualified voltages and load profiles,the manipulation details of controllable resources are simulated following a certain control sequence in each ***,the analysis results of each part are matched and filtered to obtain a complete *** types of the most commonly controllable resources are considered in this *** effectiveness of the proposed method is demonstrated through a case study based on field data from an actual distribution system.

关键词： controllable resources Distribution system DC interlink Planning Manipulation control process

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Life prediction and reliability analysis of motorbearing based on vibration signal 7

Life prediction and reliability analysis of motorbearing bas...

引用

7th International Conference on Reliability of Electrical Products and Electrical Contacts, ICREPEC 2019

作者： Xu, Helin Cheng, Lin Wan, Yuxiang Qi, Ning State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing100084 China

ISBN: (纸本)9789881532343

As an important power equipment in the power system, the electrialc motor is an important part of the transformation of electric energy and mechanical energy. Reasonable prediction of the reliability level of the running motor, timely and effectively avoid the operational risks, can effectively ensure the safety and stable operation of the power system. This paper starts with the motor vibration signal and establishes the remaining life prediction based on SVM(Support Vector Machine). Firstly, the vibration signal is denoised by wavelet transform, and the characteristic parameters such as mean square value is extracted after signal data reconstruction. Further, combined with the characteristic value, the working state is divided, and the support vector machine regression prediction model is used to obtain the remaining life of the bearing. In the case study part, data denoising and feature extraction are performed on the bearing vibration data measured by the PRONOSTIA test bench. The trend of the selected characteristic values is used for evaluating the motor operating state. The characteristic value, running state of the equipment, and remaining life which are extracted from the training set data are input to the SVM, and then the SVM is used to predict the remaining life for the test set. Finally, failure rate of the equipment can be derived. © 2019 by International Academic Publishers Ltd.

关键词： Reliability analysis

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