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作者： Shen, Yu Zhu, Fengju Zhang, Chunpeng Cai, Weiqian Yuan, Liqiang Li, Kai Zhao, Zhengming State Key Lab of Control and Simulation Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing100084 China

This study proposes a steady-state model of multi-port electric energy router (EER) and a power flow analysis method for AC/DC hybrid system considering control strategies. Firstly, a circuit topology model of EER is put forward, including AC and DC port equivalent parts. Secondly, considering external control characteristics of EER, the control strategies including PQ mode, V/f mode, and droop mode are established, which is suitable for system analysis. Then, using the extended sub-network model, an AC/DC power flow model containing multi-port EER is established. In terms of the power flow algorithm for AC/DC hybrid system, AC/DC network admittance matrix and the extended AC/DC network modification equations are applied to solve the problem. Two examples are designed and show that EER can be used for flexible power regulation and voltage improvement. Besides, power flow analysis method of AC/DC hybrid system is demonstrated to be effective. © 2019 Institution of Engineering and *** right reserved.

关键词： Topology

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The optimal circuitous communication route search for pilot protection based on ant colony algorithm 13

The optimal circuitous communication route search for pilot ...

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13th International Conference on Development in power System Protection 2016, DPSP 2016

作者： Chen, Xin Bo, Zhiqian Dong, Xingzhou Shi, Shenxing Wang, Bin State Key Laboratory of Control and Simulation of Power System and Generation Equipments China Xuji Group Corporation China

ISBN: (纸本)9781785618260

With the development of smart grid, the self-healing ability of protection device becomes much more important. Pilot protection is of good selectivity, but it needs a highly reliable communication network. Once the communication line between two devices is out of work, pilot protection will be forced out of operation. Since there are many ring structures in communication network, circuitous routes can be found to help pilot protection remain operational. In this paper, ant colony algorithm (ACA) are used to find the optimal circuitous route, and simulation results show the method is fast and accurate. To the actual communication network of power system, each node is just connected to a few other nodes, so the search process often come to dead ends. Use penalty functions can reduce the probability of coming to a dead end and improve the algorithm efficiency. The whole route accelerating penalty function is most efficient.

关键词： Timing circuits

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Adaptive Time Period Aggregation for Day-ahead Unit Commitment

Adaptive Time Period Aggregation for Day-ahead Unit Commitme...

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2022 Tsinghua-IET Electrical Engineering Academic Forum, TDF 2022

作者： Yu, Zekuan Zhong, Haiwang Yan, Xinfei Department of Electrical Engineering Tsinghua University Beijing China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Beijing China

ISBN: (数字)9781839537998

ISBN: (纸本)9781839537998

The growing penetration of renewables calls for finer temporal resolutions of the day-ahead unit commitment (DA-UC) problem in order to accommodate the fluctuations and improve the performance of UC schedules, leading to the expansion of the DA-UC problem scale. However, due to its high computational burden, the viability of adopting larger UC models in practice becomes a challenge. In this paper, an adaptive time period aggregation strategy and a corresponding DA-UC model are proposed to reduce the model scale while preserving feasibility and accuracy. The aggregation strategy integrates the statistical characteristics of net demand with the operational characteristics of thermal units to effectively capture the consistency in on/off statuses. Case study based on the IEEE 118-bus system validates that, combined with a post-processing procedure, the proposed strategy and model can provide near-optimal UC schedules with approximately 5 times acceleration for various demand profiles, enhancing computational efficiency. © 2022 IET Conference Proceedings. All rights reserved.

关键词： Computational efficiency

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Effects of temperature on creepage discharge characteristics in oil-impregnated pressboard insulation under combined AC–DC voltage

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Plasma Science and Technology 2019年第5期21卷 14-22页

作者： Fubao JIN Yuanxiang ZHOU Bin 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 Generation Equipments Department of Electrical EngineeringTsinghua UniversityBeijing 100084People's Republic of China

Due to the complexity of the valve side winding voltage of the converter transformer, the insulation characteristics of the oil-impregnated pressboard(OIP) of the converter transformer are different from those of the traditional AC transformer. The study on effect of temperature on the creeping discharge characteristics of OIP under combined AC–DC voltage is seriously inadequate. Therefore, this paper investigates the characteristics of OIP creepage discharge under combined AC–DC voltage and discusses the influence of temperature on creepage discharge characteristics under different temperatures from 70 °C to 110 °C. The experimental results show that the partial discharge inception voltage and flashover voltage decrease with increasing temperature. The times of low amplitude discharge(LAD) decrease and amplitude of LAD increases. Simultaneously, the times of high amplitude discharge(HAD) gradually increase at each stage of creepage discharge with higher temperature. The analysis indicates that the charge carriers easily accumulate and quickly migrate directional movement along the electric field ahead of discharging. The residual charge carriers are more easily dissipated after *** ‘hump’ region of LAD moves to the direction of higher discharge magnitude. The interval time between two continuous discharges is shortened obviously. The concentration of HAD accelerates the development of OIP insulation creepage discharge. The temperature had an accelerating effect on the development of discharge in the OIP under applying voltage.

关键词： oil-impregnated pressboard insulation combined AC-DC voltage inception voltage creepage discharge temperature flashover voltage

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A strategy for avoiding overload of AC line after blocking dc line in AC/DC hybrid grid 15

A strategy for avoiding overload of AC line after blocking d...

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15th International Conference on Developments in power System Protection, DPSP 2020

作者： Wang, Hao Kang, Xiaoning Dong, Xinzhou Shaanxi Key Laboratory of Smart Grid Xi'an Jiaotong University Xi'an China State Key Laboratory of Control and Simulation Power System and Generation Equipment Tsinghua University Beijing China

ISBN: (纸本)9781713827894

The development of DC transmission technique is prompting the development of AC/DC hybrid grid. As a new form of the grid, AC/DC hybrid grid faces many challenges one of which is the effect of DC blocking on AC lines. This paper analyses the influence of DC blocking on AC lines. Based on the analysis, a control strategy using wide area information is proposed to avoid the severe overload of AC line after blocking a DC line. The proposed strategy increases the transmission power of normally operating DC line aiming to afford part or all of the transmission task of the blocked DC line. The test result obtained from simulation indicates that the proposed strategy can reduce the overload of AC line after blocking a DC line. © 2020 IET Conference Publications.

关键词： Transmissions

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A Novel Method of power Swing Blocking in Impedance Relay 8

A Novel Method of Power Swing Blocking in Impedance Relay

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8th IEEE International Conference on Advanced power System Automation and Protection, APAP 2019

作者： Wang, Hao Kang, Xiaoning Dong, Xinzhou Xi'an Jiaotong University Shaanxi Key Laboratory of Smart Grid Xi'an China Tsinghua University State Key Laboratory of Control and Simulation Power System and Generation Equipment Beijing China

ISBN: (纸本)9781728117225

Distance protection is widely applied in High/Ultra- High Voltage AC transmission system. Impedance relay, the core element of distance protection, may operate incorrectly under power swing, so a power swing blocking unit is needed in distance protection. In this paper, the phase difference between the measurement voltage and compensation voltage under power swing and line fault is analyzed. Based on the analysis, a power swing blocking strategy using the change rate of phase difference between measurement voltage and compensation voltage is proposed. simulation results in PSCAD/EMTDC indicate that the proposed strategy can block the impedance relay reliably under power swing and unblock the impedance relay after detecting the fault under power swing. © 2019 IEEE.

关键词： Electric power system protection

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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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Research on operation and control of low voltage photovoltaic-energy storage DC building system 18

Research on operation and control of low voltage photovoltai...

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18th International Conference on AC and DC power Transmission, ACDC 2022

作者： Guo, Peiqian Yuan, Zhichang Han, Xuejiao Wu, Aijun Wang, Yuxuan Jiang, Zhilin State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing China Energy Internet Research Institute Tsinghua University Beijing China

ISBN: (数字)9781839537615

ISBN: (纸本)9781839537615

The spread of the power electronics, both for control and power applications, in the realization of apparatuses the DC transformation in building distribution and utilization system. Currently, the research and discussion of the operation scheme and control strategy for low voltage photovoltaic-energy storage DC building system, LVPESDCBS, are relatively less. Focusing on these, in-depth research and analysis for control and operation scheme are conducted, and the related application possibility for different types LVPESDCBSs is discussed in this paper. At the start, the existing operational control strategies for the DC system are summarized. Following this, the centralized operational control scheme, which applies to the existing buildings that need to be renovated to DC type, and the decentralized operational control scheme for newly built DC buildings are studied respectively. Taking these conclusions into consideration, a ±375V LVPESDCBS digital model with various types of AC/DC power electronic devices is established in PSCAD/EMTDC. The proposed control strategy and operational scheme are verified through normal operation and single-pole operation of this LVPESDCBS. Finally, extended marketability requirement discussions of future DC building based on three perspectives: data drives, converter devices, and the application of DC technology are presented. © ACDC 2022. All rights reserved.

关键词： Digital storage

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Nonlinear E-field simulation of HVDC Converter Transformer Busing and Its Structure Optimization With RBF Neural Network and NSGA-II Algorithm 13

Nonlinear E-field Simulation of HVDC Converter Transformer B...

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13th International Conference on power and Energy systems, ICPES 2023

作者： He, Yongsheng Zhang, Shiling Lu, Zongxiang Wang, Pengbo State Grid Chongqing Electric Power Company Chongqing Electric Power Research Institute Chongqing China State Key Lab of Control and Simulation of Power Systems and Generation Equipment Haidian China Transmission Equipment and System Security and New Technology Dept Name of State Key Laboratory of Power Chongqing China

ISBN: (纸本)9798350345063

Static DC and PR are typical operation conditions of HVDC converter transformer bushing outlet device, moreover, the electrical parameters of RIP, transformer oil and OIP have the nonlinear relationship with E-field stress and temperature. Under the temperature gradient, the electrical parameters will modify the static DC and PR E-field distribution of the composite insulation. In order to simulate static DC and PR electric field of the composite insulation structure, this paper established the full model of the converter transformer outlet. Then, the structure parameters of converter transformer outlet have been optimized using combined RBF neural network and NSGA-II algorithm. Moreover, electric field verification calculation has been carried out under AC and PR conditions. The results show that under uniform temperature condition, E-field strength is larger than that under iso-thermal condition. The overshoot coefficient of the bushing end and barrier reach 65% and 45%, respectively. The study can provide reference for the design of outlet structure of the converter transformer. © 2023 IEEE.

关键词： DC transformers

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Charge Evolution and Dielectric Property of Three-phase Polypropylene Composites With Enhanced Mechanical Performance

Charge Evolution and Dielectric Property of Three-phase Poly...

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中国物理学会第二十二届全国静电学术年会

作者： Ling Zhang Zhaowei Peng Yuanxiang Zhou Zekai Lu Yonggang Guan Zixia Cheng State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department School of Electrical Engineering Zhengzhou UniversityZhengzhou 450001China

High voltage DC(HVDC)power cable technology has the advantages of large transmission capacity,low loss,negligible electromagnetic environmental effect,and trackless corridor,etc.,which make it capable to solve the significant problem of power transmission channels during the fast development of electric ***,it also contributes to eco-friendly,resource-saving,safe,and reliable goal of power transmission *** to common crosslinked polyethylene materials,isotactic polypropylene(iPP)has the advantages of non-crosslinking,high-temperature-resistant,recyclable,low production cost,and free maintenance work,and has been a hot spot in the research field of high performance HVDC cable insulating ***,iPP is a thermoplastic limited by its impact strength,especially at low temperatures,because of its high degree of crystallinity and high glass transition *** of the common methods used to increase the impact strength is the addition of low-molecular elastomer materials or nucleating agents(NAs)into the iPP matrix,which is blended with the polymer in the molten *** previous investigations with the binary blending system have demonstrated that improved impact resistance usually was accompanied by decreasing the stiffness or deteriorating its original electrical properties in some *** order to achieve an optimum balance of macroscopic properties,adding several components is often necessary in polymer *** aim of this work is to investigate the synergistic effects on mechanical and electrical properties between NAs and different elastomers in iPP *** have shown that increasing the β-crystal content can improve its electrical property and elastomer can strengthen its mechanical performance.,Thus,three-phase iPP blends(iPP-β-x,x refers to the elastomer)were prepared with the incorporation of arylamide derivative β-NAs(TMB-5,0.2 wt%)and different elastomers(15 wt%)including styrene-bethylene butylene-b-styr

关键词： isotactic polypropylene β nucleating agent elastomer impact strength space charge

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