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Electrical tree degradation of MgO/epoxy resin composites at different voltage frequencies

High Voltage 2024年第3期9卷 581-590页

作者： Yunxiao Zhang Wenxin Lin Yuanxiang Zhou Weiwei Xing Jiayu Cheng Chenyuan Teng College of Electrical Engineering and Automation Fuzhou UniversityFujian Key Laboratory of New Energy Generation and Power ConversionFuzhouChina State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department of Electrical EngineeringTsinghua UniversityBeijingChina

Electrical tree degradation is one of the main causes of insulation failure in high-frequency *** tree degradation is studied on pure epoxy resin(EP)and MgO/EP composites at frequencies ranging from 50 Hz to 130 *** results show that the tree initiation voltage of EP decreases,while the growth rate and the expansion coefficient increase with ***,the bubble phenomenon at high frequencies in EP composites is *** with trap distribution character-istics within the material,the intrinsic mechanism of epoxy composites to inhibit the growth of the electrical tree at different frequencies is *** can be concluded that more deep traps and blocking effect are introduced by doping nano-MgO into EP bulks,which can improve the electrical tree resistance performance of EP composites in a wide frequency range.

关键词： composites tree Electrical

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Comprehensive power-supply planning for active distribution system considering cooling,heating and power load balance

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Journal of Modern power systems and Clean Energy 2015年第4期3卷 485-493页

作者： Xinwei SHEN Yingduo HAN Shouzhen ZHU Jinghong ZHENG Qingsheng LI Jing NONG State Key Lab of Control and Simulation of Power Systems and Generation Equipments Department of Electrical EngineeringTsinghua UniversityBeijing 100084China Grid Planning&Research Center Guizhou Power Grid CooporationCSGGuiyang 550002China

An active distribution system power-supply planning model considering cooling,heating and power load balance is proposed in this paper.A regional energy service company is assumed to be in charge of the investment and operation for the system in the *** expansion of substations,building up distributed combined cooling,heating and power(CCHP),gas heating boiler(GHB)and air conditioner(AC)are included as investment planning *** terms of operation,the load scenarios are divided into heating,cooling and transition ***,the extreme load scene is included to assure the power supply reliability of the *** results demonstrate the effectiveness of the proposed model and illustrate the economic benefits of applying distributed CCHP in regional power supply on investment and operation.

关键词： Active distribution system Combined cooling heating and power(CCHP) power-supply planning Load balance

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A new transient stability margin based on dynamic security region and its applications

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Science China(Technological Sciences) 2008年第6期51卷 751-760页

作者： XUE AnCheng1, 2 & MEI ShengWei1 1 state key lab of power systems, Department of Electrical Engineering, Tsinghua University, Beijing 100084, China 2 key lab of systems and control, Institute of systems Science, Chinese Academy of Sciences, Beijing 100190, China State Key Lab of Power Systems Department of Electrical Engineering Tsinghua University Beijing 100084 China Key Lab of Systems Control Institute of Systems Science Chinese Academy of Sciences Beijing 100190 China

A new transient stability margin is proposed based on a new expression of dynamic security region (DSR) which is developed from the existing expression of DSR. Applications of the DSR based transient stability margin to contingency ranking and screening are discussed. simulations in the 10-machine 39-bus New England system are performed to show the effectiveness of the proposed DSR based tran-sient stability margin.

关键词： dynamic security region (DSR) transient stability margin contingency screening

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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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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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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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Wind power forecasting errors modelling approach considering temporal and spatial dependence

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Journal of Modern power systems and Clean Energy 2017年第3期5卷 489-498页

作者： Wei HU Yong MIN Yifan ZHOU Qiuyu LU The State Key Lab of Power Systems Department of Electrical EngineeringTsinghua UniversityBeijingChina Power Dispatch Control Centre of Guangdong Power Grid Corporation GuangzhouChina

The uncertainty of wind power forecasting significantly influences power systems with high percentage of wind power generation. Despite the wind power forecasting error causation, the temporal and spatial dependence of prediction errors has done great influence in specific applications, such as multistage scheduling and aggregated wind power integration. In this paper, Pair-Copula theory has been introduced to construct a multivariate model which can fully considers the margin distribution and stochastic dependence characteristics of wind power forecasting errors. The characteristics of temporal and spatial dependence have been modelled, and their influences on wind power integrations have been *** comparisons indicate that the proposed model can reveal the essential relationships of wind power forecasting uncertainty, and describe the various dependences more accurately.

关键词： Pair-Copula Wind power forecasting Temporal dependence Spatial dependence Wind power integrations

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A Novel Modeling Method for power Flow Calculation of Integrated Enegy Network 13

A Novel Modeling Method for Power Flow Calculation of Integr...

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2022 IEEE International Conference on power systems Technology, powerCON 2022

作者： Tian, Liting Zhou, Xuyan Lin, Cheng Yin, Zheng Lin, Ende Equipment Tsinghua University State Key Laboratory of Control and Simulation of Power Systems and Generation Beijing China Institute of Science and Technology China Three Gorges Corporation State Key Laboratory of Control and Simulation of Power Systems Beijing China

ISBN: (数字)9781665417754

ISBN: (纸本)9781665417754

Multi-energy systems may contain integrated energy networks such as electrical, gas and heating networks. The differences in the physical characteristics of each energy network make it difficult to solve power flows of the integrated energy networks. Based on the concept of energy flow, this paper realizes the unified modeling of electrical, gas and heating network to describe the stable equilibrium relationship. The basic equations for energy flow calculation contains Kirchhoff's Current Law equations, Kirchhoff's Voltage Law equations, and energy flow efficiency equations. A weighted directed graph is used to model the total system with networks and energy hubs. The proposed model is used for the joint power flow solution of the multi-energy system with Newton-Raphson algorithm. Finally, the validity and accuracy of the model are verified in a test system. © 2022 IEEE.

关键词： Newton-Raphson method

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Measurement-based solution for low frequency oscillation analysis

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Journal of Modern power systems and Clean Energy 2016年第3期4卷 406-413页

作者： Chen SHEN Zhi AN Xianzhong DAI Wei WEI Lijie DING Department of Electrical Engineering Tsinghua UniversityBeijingChina State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Tsinghua UniversityBeijingChina Electric Power Research Institute of Sichuan Electric Power Company ChengduChina

This paper presents a measurement-based solution for low frequency oscillation(LFO) analysis in both real time monitoring and off-line case study. An online LFO property discrimination method is developed first,which alternately uses empirical mode decomposition(EMD)/Hilbert transform(HT) and square calculation to process the measurement data. The method magnifies the variation trend of oscillating variables to accurately discriminate the property of the oscillation. Subsequently, an oscillation source locating method for the forced oscillation(FO) and a strongly correlated generator identification method for the weak damping oscillation(WDO) are proposed. Finally, numerical study results on a test system of the isolated Changdu grid in Tibet validate the proposed methods.

关键词： Low frequency oscillation Oscillation property discrimination Oscillation source location Strongly correlated generator identification

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Switching Current Imbalance Mitigation for Paralleled SiC MOSFETs Using Common-mode Choke in Gate Loop 12

Switching Current Imbalance Mitigation for Paralleled SiC MO...

引用

12th Annual IEEE Energy Conversion Congress and Exposition, ECCE 2020

作者： Liu, Jiye Zheng, Zedong Tsinghua University State Key Lab of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Beijing China

ISBN: (纸本)9781728158266

Paralleling SiC MOSFETs is a popular way to increase the current capacity. However, due to asymmetric layout, device parameter mismatch and other factors, imbalanced switching or dynamic current is observed among the paralleled switches in multi-device paralleling application which results in unequal switching loss, challenging the security and reliability of the system. In this paper, a common-mode choke in the gate loop is proposed and analyzed to suppress the imbalanced switching current induced by asymmetric layout in a half-bridge configuration with a Kelvin-source connection. The mechanism of the proposed method is comprehensively investigated to show that though the common-mode choke is placed in the gate loop, it can also mitigate the imbalanced current caused by asymmetric power loop. And it also shows that only the leakage inductance of the choke is seen in the gate loop and thus the switching speed is not expected to be influenced. The proposed method can be easily extended to multi-device paralleling application and the switching transients is hardly influenced by the common-mode choke. simulation and experimental results are presented to verify the proposed method. © 2020 IEEE.

关键词： Silicon

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