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11th Asia-Pacific International Conference on Lightning, APL 2019

作者： Meng, Pengfei Wan, Shuai He, Jinliang Zhao, Xiaolei Xu, Heng Yang, Xiao Hu, Jun State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China Wuhan NARI Limited Liability Company State Grid Electric Power Research Institute Wuhan China

ISBN: (纸本)9781728116952

In this work, we studied multiple dopants based ZnO varistors and optimizing its microstructure and electrical properties by tailoring the sintering characteristics. The properties were evaluated by scanning electron microscopy (SEM), current-voltage characteristics, capacitance-voltage characteristics, dielectric characteristics and X-ray diffraction characteristics. At a given gallium and indium concentration, the residual voltage ratio of the sintered varistors under the 5/20μs impulse current decreased obviously as the sintering temperature increased from 1100°C to 1250°C. Besides, the nonlinear coefficient was first increased and then decreased with increasing sintering temperature. The multiple doped ZnO varistors sintered at 1250°C showed optimal performance, exhibiting a grain size of 7.1μm, residual voltage ratio of 1.56, voltage gradient of 416 V/mm, leakage current of 0.79 μA/cm2, and nonlinear coefficient of 73. When applied in power systems, the high voltage gradient varistors will make the line surge arrester in better coordination with insulators as well as reach the goal of low cost and miniaturization of GIS tank-type arresters. © 2019 IEEE.

关键词： Varistors

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Evaluating Comprehensive Development Quality of a Regional power Grid by Using an Integrated Multi-criteria Decision-Making Methodology 6

Evaluating Comprehensive Development Quality of a Regional P...

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2019 6th International Conference on Advanced Composite Materials and Manufacturing Engineering, ACMME 2019

作者： Zhang, Xiaodong Qin, Kaiming Si, Ruihua Ge, Xianjun State Grid Henan Electric Power Company Zhengzhou450018 China State Key Laboratory of Power System and Power Generation Equipment Control and Simulation Department of Electrical Engineering Tsinghua University HaidianBeijing100084 China

Due to the economic situation changes and the continuous expansion of new energy power in China, a new evaluation methodology based on multi-criteria decision making (MCDM) should be proposed to promote the comprehensive development of the new regional power grid. Some criteria were selected to constitute an indicator system from the perspectives of the safety reliability, network structure and economic benefit. Then, an integrated evaluation model was proposed based on fuzzy AHP method and VIKOR method was applied to calculate a series of comprehensive evaluation indexes. A regional power grid was chosen as an empirical analysis to demonstrate the feasibility of the evaluation system. © Published under licence by IOP Publishing Ltd.

关键词： Decision making

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From Distributed Energy Resources to Virtual power Plants: A Cyber-Physical System Solution for Integrating Demand-side in Smart Grid

From Distributed Energy Resources to Virtual Power Plants: A...

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IEEE Conference on Energy Internet and Energy System Integration (EI2)

作者： Liting Tian Lin Cheng Yuxiang Wan Kai Yuan Rui Liu Kuihua Wu State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing China State Grid Economic & Technology Research Institute Beijing China Economic & Technology Research Institute State Grid Shandong Electric Power Company Jinan China

ISBN: (数字)9781728196060

ISBN: (纸本)9781728196077

Distributed Energy Resources(DERs) will be an important part of the future power system under the spread of distributed renewable energy generation, electric vehicles, demand response and other technologies. Cyber-physical system (CPS) is one of the development directions for the future smart grid to integrate the widespread DERs. First, this paper presents the basic architecture and operation process of virtual power plant (VPP). Then the solution of communication structure and software platform are proposed. It is pointed out that virtual power plants have good applicability in information and communication infrastructure, power market and DER integration. Finally, a demonstration program in China is introduced. The research and application of virtual power plant is currently in its embryonic form. It provides a solution for the transmission from centralized power production to the distributed energy utilization, and is an adequate way to integrate geographical dispersion, heterogeneous DERs.

关键词： Renewable energy sources Transforms System integration Cyber-physical systems power markets Software Smart grids

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A Gate Driver with a Negative Turn Off Bias Voltage for GaN HEMTs

A Gate Driver with a Negative Turn Off Bias Voltage for GaN ...

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International Conference on power Electronics and Motion control (IPEMC)

作者： Hang Zhou Matthew Priestley John Fletcher Kai Sun School of Electrical Engineering and Telecommunications University of New South Wales Sydney Australia State Key Lab of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing China

ISBN: (数字)9781728153018

ISBN: (纸本)9781728153025

The GaN HEMT offers fast switching and low on-state resistance which makes it ideal for applications such as high efficiency and high power density power supplies. Unfortunately, the low threshold voltage makes GaN HEMT extremely vulnerable to false turn-on, which compromises the performance and potentially causes shoot-through. In the half-bridge circuit topology, the resonant circuit formed by the parasitic inductance and capacitance can trigger false turn-on with a fast commutation. A practical method to avoid this phenomenon is to apply a negative bias voltage during the commutation by either using a separate power supply or using a capacitor charge pump to produce the negative turn-off bias. The first method necessitates many extra components and the second method cannot provide a fixed negative voltage. This paper rectifies these issues by proposing a negative turn-off bias generator with a new charge pump based approach which offers a stable negative turn-off voltage under different switching frequencies and duty cycles. The proposed circuit has been practically implemented during experimental testing. These results demonstrate that false turn-on events are eliminated without compromising the high-frequency and highspeed characteristics of the GaN HEMT.

关键词： Resistance Charge pumps Switching frequency Capacitors HEMTs Threshold voltage Gallium nitride

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The Influence of Positive Temperature Coefficient Material on the DC Electric Field within Epoxy Composites

The Influence of Positive Temperature Coefficient Material o...

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Conference on Electrical Insulation and Dielectric Phenomena, (CEIDP)

作者： Chenyuan Teng Yuanxiang Zhou Ling Zhang Yunxiao Zhang Xuewei Wang Zixia Cheng Meng Huang China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing China The Wind Solar Storage Division of State Key Laboratory of Power System and Generation Equipment School of Electrical Engineering Xinjiang University Urumqi China School of Electrical Engineering Zhengzhou University Zhengzhou China The State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University Beijing China

ISBN: (纸本)9781728195728;9781728195735

Negative temperature (NT) coefficient electrical resistivity of insulating materials causes the distortion of DC electric field, increasing the design and manufacture difficulty of HVDC equipment. The ceramic with positive temperature coefficient (PTC) electrical resistivity was doped into epoxy resin to weaken its temperature dependence of electrical resistivity (0~35 wt%). The electric field and temperature distribution under temperature gradient were simulated. The PTC effect of fillers is able to mitigate the distortion of electric field under temperature gradient, which is through the synergistic optimization of both electrical resistivity-temperature characteristic and thermal conductivity. The optimization of electric field distribution within insulation via BT60/epoxy composites has potential to be used in HVDC electrical equipment.

关键词： Temperature sensors Temperature distribution Temperature dependence Thermal resistance HVDC transmission Conductivity Thermal conductivity

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Effect of UV radiation aging on creepage discharge characteristics of high temperature vulcanized silicon rubber at high altitude

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Plasma Science and Technology 2019年第5期21卷 23-33页

作者： Fubao JIN Yuanxiang ZHOU Bin LIANG Xidong LIANG Zhongliu ZHOU Ling ZHANG Key Laboratory of Plateau Ecology and Agriculture College of Agriculture and Animal HusbandrySchool of Water Resources and Electric PowerQinghai UniversityXining 800016People's Republic of China State Key Lab of Control and Simulation of Power Systems and Gen eration Equipments Departme nl of Electrical EngineeringTsinghua UniversityBeijing 100084People's Republic of China

The physicochemical properties and creepage discharge characteristics of aged high temperature Vulca nized(HTV)silicone rubber materials were investigated by ultraviolet radiati on(UV)aging method in this *** experimental results show that as the aging time increases,the creepage discharge flashover voltage increases first and then *** the aging time has little effect on the creepage discharge inception *** the aging time prolonged,the discharge endurance time of HTV silicone rubber is shortened,and the creepage discharge development velocity is *** the short time of applying voltage to aging material,the magnitude of discharge in creases *** to the partial discharge characteristic parameters of creepage discharge,the whole creepage discharge process is partitioned into four *** with unaged HTV silicone rubber,the aged HTV silicone rubber has less fluctuation in performance parameters and a clear *** study found that UV aging not only affects the physicochemical and hydrophobic properties of the HTV silicone rubber,but also accelerates the development of creepage discharge under AC voltage.

关键词： high temperature vulcanized silicone rubber creepage discharge UV aging inception voltage flashover voltage high altitude characteristic parameters

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The parameter design method of smoothing inductance based on MMC-MTDC with R-type superconducting fault current limiter

The parameter design method of smoothing inductance based on...

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The 16th IET International Conference on AC and DC power Transmission (ACDC 2020)

作者： P. Guo Z. Yuan G. Liu Y. Zhao Z. Shi Tsinghua University State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Beijing China Shenzhen Power Supply Corporation Shenzhen China Sichuan Energy Internet Research Institute Tsinghua University Chengdu China

The rapid increase of voltage sourced converter brings the great development of the multi-terminal DC technology, both in the DC transmission and DC distribution fields. However, because of the weak impedance characteristic of the VSC-HVDC system, how to suppress and clear DC fault currents becomes a challenge. Considering the stability, the response speed and the system structure, it is not possible to apply excessive inductance at the DC side, hence, the current limiting effectiveness is relatively restricted. On the one hand, with the effective properties, Resistive type Superconducting Fault Current Limiter (R-SFCL) becomes an effective device to solve the problem of VSC-HVDC system under DC faults. On the other hand, because of dynamic energy-impedance characteristics of R-SFCL, the fixed impedance selection method at a certain time to carry out dynamic current limiting analysis is no longer applicable. Therefore, the DC fault current research and R-SFCL characteristic are comprehensively analyzed firstly in this paper. Based on that, a smoothing inductance determination method is proposed to cut off the DC fault current by DC breaker and ensure the continuous operation of remaining parts. Finally, based on a multi-terminal DC system simulation, the improvement and effectiveness of the proposed method are validated.

关键词： power transmission faults HVDC power transmission superconducting fault current limiters HVDC power convertors voltage-source convertors

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Field Measurement and Analysis on The Characteristics of Transient Enclosure Voltage and Transient Ground Potential Rise in UHV GIS Substation

Field Measurement and Analysis on The Characteristics of Tra...

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International Conference on High Voltage Engineering and Application, ICHVE

作者： Shen Wei Wang Sen Wu Tao Yang Fan Gao Bing Liu Zhuoran Electric Power Research Institute State Grid Shaanxi Electric Power Company Xi'an China State Key Laboratory of Power Transmission Equipment & System Security and New Technology Chongqing University Chongqing China State Key Laboratory of Control and Simulation of Power System and Generation Equipments Tsinghua University Beijing China

ISBN: (数字)9781728155111

ISBN: (纸本)9781728155128

During the switching operation of GIS Substation, the Transient Enclosure Voltage (TEV)and the Transient Ground Potential Rise (TGPR) will occur, which will have a negative impact on the safety of substation. In this paper, TEV and TGPR are measured and analyzed in a 750kV substation at different locations of GIS, under three types of operation of disconnect switch and circuit breaker, include: single closing of disconnect switch, single closing of circuit breaker, three times opening and closing of circuit breaker. From the results, the maximum value of TEV and TGPR is 22.8 kV and 19.6kV, respectively, and the TGPR is higher than the TEV at many measuring points; Compared with the circuit breaker closing operation, the disconnect switch closing operation produces less electromagnetic oscillation energy, but it have longer macro-pulse duration and more breakdown times, which explained that the failure of secondary system caused by the operation of disconnect switch is more than caused by the operation of circuit breaker; Three times opening and closing operation of the circuit breaker produces stronger electromagnetic energy and more breakdown than single closing operation of the circuit breaker.

关键词： Circuit breakers Transient analysis Substations Gas insulation Switching circuits Switches Insulators

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Research on Lithium-ion Battery Safety Risk Assessment Based on Measured Information

Research on Lithium-ion Battery Safety Risk Assessment Based...

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Sustainable power and Energy Conference (iSPEC)

作者： Xuyan Zhou Lin Cheng Yuxiang Wan Ning Qi Liting Tian Feng You State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing China Energy Storage System Business Unite Tianjin Lishen Battery Joint-Stock Co. Ltd. Tianjin China

ISBN: (数字)9781728191645

ISBN: (纸本)9781728191652

Lithium-ion batteries have the advantages of high energy density, fast power response, recyclability, and convenient to movement, which are unsurpassed by other energy storage systems. However, safety issues such as thermal runaway of lithium-ion batteries have become the main bottlenecks restricting the development of their extensive applications. In practical applications, the demand for battery energy storage scale and specific energy continues to increase, and the contradiction between battery high safety and battery safety has become increasingly prominent. This paper proposes a lithium-ion battery safety risk assessment method based on online information. Effective predictions are essiential to avoid irreversible damage to the battery and ensure the safe operation of the battery energy storage system before a failure occurs. This paper is expected to provide novel risk assessment method and research idea for the development and design of high-safety battery systems.

关键词： Lithium-ion batteries Temperature measurement Voltage measurement Thermal management Battery charge measurement Safety Risk management

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Discrete state Event-Driven Framework for simulation of Switching Transients in power Electronic systems

Discrete State Event-Driven Framework for Simulation of Swit...

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IEEE Energy Conversion Congress and Exposition

作者： Yicheng Zhu Zhengming Zhao Bochen Shi Jiahe Ju Zhujun Yu Liqiang Yuan Kainan Chen State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing China

Accurate and efficient simulation of device-level switching transients together with system-level dynamics in power electronic systems is challenging due to stiffness and intensive discontinuous points introduced by discrete system events. In this paper, a switching transient simulation mechanism is proposed to combine the discrete state event-driven (DSED) simulation framework and the piecewise analytical transient (PAT) model together to overcome such difficulties. key elements of this simulation framework for switching transient simulation include: 1) a commutation-unit-based (CUB) method for switching transient simulation and 2) a time-scale-decoupling (TSD) simulation mechanism. The proposed simulation framework is applied to a 50kVA solid-state transformer (SST) to verify its accuracy and efficiency. DSED simulated and experimental waveforms are in excellent agreement. Up to 5.3-fold and 717.3-fold improvements in simulation speed are achieved at the same level of accuracy compared with Simulink simulation with ideal switch models and Saber simulation with physics-based device models, respectively.

关键词： Transient analysis Switches Integrated circuit modeling Switching circuits Mathematical model Computational modeling

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