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CIGRE Session 46

作者： Xie, S.J. Li, J.M. Zhang, Y. Zeng, R. Zhuang, C.J. Wang, H. State Grid Sichuan Electric Power Research Institute State Grid Sichuan Electric Power Company China State Key Lab. of Control and Simulation of Power Systems and Generation Equipment Tsinghua University China

Obtaining the lightning strike density along an overhead transmission line and identifying the lightning strike types are the key to evaluating the lightning protection performance and proposing reasonable protection schemes of transmission lines. In addition, the waveform characteristics of lightning invasion overvoltage are the basis to establish the standard on the insulation tests of power equipment. Measuring the transient process of lightning striking overhead transmission lines is the basis to carry out the work mentioned above. In this paper, a distributed measurement method of transient current on conductors caused by lightning strikes is proposed. The measuring units are installed on the field conductors of transmission lines every 30 km to obtain less-distorted transient current waveforms. In order to enable measuring units to work in field isolated environment, a power supply coil using Faraday electric-magnetic effect and a wireless communication module is designed and developed. By far, 4776 measuring units have been installed on 597 transmission lines of China's power grid. According to measured transient current waveforms, the lightning strike point can be located using the double-end or single-end travelling wave location method, and the lightning strike type can also be identified. Moreover, a novel measurement method of lightning transient voltage based on the integrated optical electric field sensor (IOEFS) is proposed. In this method, the transient voltage waveforms are inversed from space electric field waveforms measured by IOEFSs. A series of performance tests of IOEFS have been carried out. The test results indicate that the response speed can reach several nanoseconds, and the frequency response can cover 5Hz∼100MHz which is wide enough for the measurement of the lightning transient voltage. In order to test the field measurement effect, the measurement equipment is used to measure a transient voltage when a group of capacitor voltage trans

关键词： Frequency response

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Application and Practice of Digital Twin Technology in Monitoring Status of power Equipment in Converter Valve Hall

Application and Practice of Digital Twin Technology in Monit...

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2023 International Conference on Intelligent Communication and Computer Engineering, ICICCE 2023

作者： Yongsheng, He Baojia, Deng Zongxiang, Lu Shiling, Zhang Liangjun, Dai State Grid Chongqing Electric Power Company Electric Power Research Institute China State Key Lab of Control and Simulation of Power Systems and Generation Equipment Deptartment of Electrical Engineering Tsinghua University China

ISBN: (纸本)9798350395617

The internal power equipment of ultrahigh voltage converter valve hall is numerous and complex in structure, involving the various information elements such as the temperature and vibration. Moreover, the gas inside ultra-high voltage converter bushing is SF6 gas. Under the current over-load condition of the converter bushing, SF6 gas will decompose. This article focuses on the SF6 gas equipment inside the ultrahigh pressure converter valve hall as the research object, and analyzes specific types and content of SF6 gas decomposition products. In order to effectively detect gas content in the digital twin model of the converter transformer bushing, the new portable SF6 gas chromatograph, laser detection technology and device for HF gas, and partial discharge detection technology research using the acoustic electric coupling method are carried out, providing the effective means for onsite detection of hidden faults in operating equipment. Research has shown the digital twin technology can effectively detect the absorption spectra of gases such as O2, H20, CO, CO2, CF4, SO2, H2S, SOF2, and SO2F2. On the other hand, through digital twin partial discharge detection technology, it is effectively found that the SO2 inside the UHV converter sleeve is 29μL/L, H2S is 4μL/L, CO is 36μL/L, HF=0, detected SO2 and H2S components, determined as the insulation heating defect. The research results of paper provide theoretical and data support for operation status monitoring of SF6 gas insulated power equipment inside the ultra-high voltage converter valve hall. © 2023 IEEE.

关键词： Sulfur hexafluoride

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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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High impedance fault detection on distribution systems with harmonic interference in wind farms 13

High impedance fault detection on distribution systems with ...

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

作者： Ni, Jiang Wang, Bin Dong, Xinzhou State Key Lab of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing100084 China

ISBN: (纸本)9781785618260

High impedance faults (HIFs) are easy to occur in collective feeders in wind farms and may cause the cascading of wind generators tripping. This kind of faults is difficult to be detected by traditional relay or fuse due to the limited fault current values and the situation is worse in wind farms. The mostly adopted HIF detection algorithms are based on the 3rd harmonic characteristic of the fault zero-sequence currents, whereas these 3rd harmonics are very easy to be polluted by wind power back-to-back converters. To solve this problem, the typical HIF arc flash based on Mayr's arc model is first built, and the typical fault waveforms of HIF in wind farm are presented. Then the characteristics of high impedance faults are analysed to distinguish the occurrence of HIF from other harmonic interference. After that, the performance of the traditional harmonic based HIF detection algorithm is discussed, and a novel detection algorithm is presented to prevent harmonic interference influence in wind farms.

关键词： Electric utilities

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Probabilistic substation fault diagnosis considering instrumentation channels and heterogeneous information: A unified Bayesian network model

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Qinghua Daxue Xuebao/Journal of Tsinghua University 2014年第10期54卷 1384-1390页

作者： Mu, Jianan Sun, Hongbin Wu, Wenchuan Guo, Qinglai Zhang, Boming State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing100084 China

Fault diagnosis plays an important role in improving power network troubleshooting capability. Conducting local fault diagnosis in substations can make full and quick use of abundant local information. A substation fault diagnosis method was presented based on Bayesian network to adapt to a wealth of information and distributed autonomy under smart grid environment. The method is effective in dealing with uncertainties induced by malfunctions of protection relays and circuit breakers as well as instrumentation channel errors. Heterogeneous information available in substations, such as sequence of events (SOEs), wave records and blocking signals, was also integrated into the method, with the junction tree algorithm used to conduct probabilistic reasoning. The results show that breaker SOEs can be better utilized when considering instrumentation channels. Furthermore, introduction of wave records and blocking signals can significantly improve diagnosis accuracies. ©, 2014, Press of Tsinghua University. All right reserved.

关键词： Bayesian networks

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Movement simulation of long electric arc along the surface of insulator string in free air

Movement simulation of long electric arc along the surface o...

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作者： Gu, Shanqiang He, Jinliang Zhang, Bo Xu, Guozheng Han, Shejiao State Key Lab of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing 100084 China

This paper presents the study of a long electric arc in free air due to lightning stroke on the parallel gap lightning protection device (PGLPD) on high-voltage overhead transmission lines. Based on the latest electric arc model, the analysis method of the magnetic field generated by the current flowing through the PGLPD, electric arc, transmission lines, steel tower, and ground wires is developed, and the movement process of the long arc along the surface of the insulator strings is simulated. The simulation results are in agreement with the experimental results. The study is very helpful for the optimal design and suitable assemblage of the PGLPD. © 2006 IEEE.

关键词： Electric arcs

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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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Common-mode voltage reduction for three-phase-to-four-leg direct matrix converter with a novel control strategy

Common-mode voltage reduction for three-phase-to-four-leg di...

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2017 IEEE Transportation Electrification Conference and Expo, Asia-Pacific, ITEC Asia-Pacific 2017

作者： Huang, Songtao Guo, Yougui Xu, Lie Li, Yongdong School of Information and Engineering Xiangtan University Xiangtan China State Key Lab of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing China

ISBN: (纸本)9781538628942

Due to the three-phase-to-three-leg direct matrix converter (3 × 3 MC) cannot be achieved with unbalanced load, then the three-phase-to-four-leg direct matrix converter (3 × 4 MC) is introduced. A novel modulation strategy is proposed to ensure the capability of 3 × 4 MC with arbitrary loads, which is development by using fixed voltage vectors and one zero vector. Considering the harm of common-mode voltage (CMV), the switch configurations of the proposed modulation strategy are improved. Selecting the reasonable zero vectors by the subsection partition, which is capable of reducing the CMV to half of the input source voltage produced by the zero vectors, and the ability of 3 × 4 MC with arbitrary load is also realized. The feasibility of the proposed strategy is verified by the accompanying simulation results. © 2017 IEEE.

关键词： Matrix converters

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Steady-state model of multi-port electric energy router and power flow analysis method of AC/DC hybrid system considering control strategies

Steady-state model of multi-port electric energy router and ...

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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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Transient Behaviors of Space Charge in Low-density Polyethylene Films at Prebreakdown Under Temperature Fields

Transient Behaviors of Space Charge in Low-density Polyethyl...

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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 Zekai Lu Yuanxiang Zhou Zhaowei Peng Zixia Cheng Yonggang Guan 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

Currently,insulation performance of high voltage DC(HVDC)power cables is still of critical significance challenge in both engineering application and fundamental *** example,HVDC cable insulation suffers breakdown under the conditions of cold start and load cycling tests,and the presence of space charge at high temperatures causes electric field distortion within the ***,the operating temperature of HVDC cables could only reach 70℃at *** work intends to carry out research on the effect of temperature on space charge characteristics of low-density polyethylene(LDPE)films at prebreakdown under a linearly ramping voltage,which is of great significance for further understanding and improving the operating temperature and breakdown strength of HVDC ***-free LDPE film with a thickness of 100 μm was purchased from GoodFellow *** improved space charge measurement system was developed with a high-speed measurement interval of 1 ms,a high voltage pulse of 120 V,and a pulse width of 5 ns.A linearly ramping voltage of 0.5 kV/s was selected and cut off after breakdown *** and steady behaviors of space charge was comprehensively sudied under a linearly ramping voltage of 500 V/s at 30℃and 70℃,*** results show that negative charge was rapidly injected and accumulated near the anode at a relatively low electric field at 70℃.As the applied electric field gradually increased,the anode appeared a significant positive charge *** phenomenon occurred when charge packets were injected to a certain distance of~30 μ*** the contrast,there was only negative charge injection and accumulation in the bulk of LDPE films at 30℃,and breakdown was not observed even when the voltage rose to-30 *** was found that the anode had a positive space charge packet injection at 30℃and slowly migrated to the cathode,and the entire transit process took tens of *** the internal electric field distribution,the ma

关键词： LDPE prebreakdown transient space charge internal field distortion carrier mobility

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