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International Journal of electrical power & Energy systems 2024年 158卷

作者： Yao Zou Qianggang Wang Bo Hu Yuan Chi Guiping Zhou Fei Xu Niancheng Zhou Qinqin Xia State Key Laboratory of Power Transmission Equipment Technology School of Electrical Engineering Chongqing University China State Grid Liaoning Electric Power Company Limited Shenyang Liaoning China State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China

Research on Transforming Effect and Calculation Method of MMC Converter on AC / DC Harmonics

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Research on Transforming Effect and Calculation Method of MM...

Sustainable power and Energy Conference (iSPEC)

作者： Liu Cui Guangqiang Peng Jingsong He Jiyang Wu Chizu Mao Ning Jiao State Key Laboratory of HVDC Electric Power Research Institute China Southern Power Grid GuangZhou China Guangdong Provincial Key Laboratory of Intelligent Operation and Control for New Energy Power System GuangZhou China CSG Key Laboratory for Power System Simulation Electric Power Research Institute China Southern Power Grid GuangZhou China Maintenance & Test Center EHV Power Transmission Company Guangzhou CSGKEY LABORATORY FOR DC TRANSMISSIONEQUIPMENT STATE EVALUATION AND FAULT DIAGNOSIS GuangZhou China College of Electrical Engineering and Information Technology Sichuan University Chengdu China

ISBN: (纸本)9781665414401

Modular multilevel converter (MMC) is currently the most concerned voltage source converter topology in the field of flexible direct current transmission (VSC-HVDC). Due to its non-linear characteristics, harmonic components will inevitably be generated in AC and DC systems, which may affect the operation of equipment and system, cause protection equipment to malfunction, and cause interference to neighboring communications. The MMC converter is a non-linear device, which can be considered as an amplifying modulator with voltage and current conversion functions. The AC and DC networks are coupled to each other through the MMC converter to generate dynamic harmonic interaction. In recent years, harmonic instability problems have appeared in many VSC-HVDC projects. Compared with other converter topologies, the transfer relationship of harmonics on the AC and DC sides of MMC converters has not been studied in depth. In this paper, by studying the AC/DC harmonic conversion characteristics of MMC converters, it reveals the conversion law of MMC converters between AC/DC harmonics; through theoretical derivation, the quantitative calculation method of MMC harmonic transmission process is given. PSCAD simulation results prove the correctness of the above results.

关键词： Network topology simulation Bridge circuits Voltage power system harmonics Harmonic analysis Frequency conversion

Research on control strategy and dynamic test of multi-port electric energy router

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Journal of Physics: Conference Series 2021年第1期1971卷

作者： Zaixin Yang Xusheng Jian Sitai Ya Inner Mongolia Enterprise Key Laboratory of Smart Grid Simulation of Electrical Power System Inner Mongolia Power Research Institute Hohhot 010020 China

Researching an electric energy router and analyzing the control and operation characteristics are of significant importance for bi-high power system. In this study, a multi-modal two-level coordinated control strategy of multi-port electric energy router is proposed to achieve fast and flexible regulation of power flow. a prototype of multi-port energy router is trial-produced with an energy storage system, a sending-end power grid and a receiving-end power grid. Furthermore, a comprehensive dynamic test for the prototype of multi-port energy router is completed. The results show that the dynamic performance of the multi-port energy router in power step test is found to conform to the test standard. The charging and discharging modes of the energy storage unit under multi-modal control strategy are switched correctly. During the energy exchange process, multi-port AC/DC voltage operates stably. It can be applied to multi-port, multi-cascade, multi-flow distribution network.

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Reliability Evaluation of a Regional Integrated Energy system Based on Complex Network Theory

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Reliability Evaluation of a Regional Integrated Energy Syste...

Sustainable power and Energy Conference (iSPEC)

作者： Jifeng Li Kuizheng Song Xingtang He Hao Luo Dalian Electric Power Supply Company State Grid Liaoning Electric Power Supply Co. Ltd Dalian China Dispatching and Control Center State Grid Liaoning Electric Power Supply Co. Ltd Shenyang China Key Laboratory of the Ministry of Education on Smart Power Grids Tianjin University Tianjin China Key Laboratory of Modern Power System Simulation and Control & Renewable Energy Technology Northeast Electric Power University Jilin China

ISBN: (纸本)9781665414401

Most of the methods currently used to evaluate the reliability of integrated energy supply mainly consider such systems on a microgrid scale and focus on the effects of interactions among various energy carriers on the overall energy supply reliability of the system. As a result, it is difficult to analyze the system reliability in terms of its topology. Therefore, this paper proposes an approach for evaluating the reliability of a regional integrated energy system based on complex network theory. First, the feasibility of complex network theory application was analyzed based on the structural framework of the regional integrated energy system. Then, a weighted complex network model containing network characteristics was constructed by improving the “distance” parameter in the complex network theory. Employing this model enabled the proposal of reliability evaluation indices, including nodes and the entire system, from the perspective of the system network topology. Finally, the effectiveness and applicability of the developed method were verified by constructing a test system. The application of complex network theory for reliability evaluations of regional integrated energy systems described in this paper provides guidance for planning and constructing future systems at the level of topology reliability.

关键词： Couplings Complex networks Microgrids Energy conversion Reliability theory Propagation losses Topology

First-Principles Study of Electronic Structure and Metallization of Mg2pb Under High Pressure

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SSRN 2023年

作者： Li, Yuqiang Li, Yuhong Zhang, Qiang Su, Ningning Sun, Jinlu Xiao, Ningru Liu, Yang Liu, Yuyao Ning, Pingfan Liu, Hongwei Tianjin Key Laboratory of Optoelectronic Detection Technology and Systems School of Electronics and Information Engineering Tiangong University Tianjin300387 China Key Laboratory of Smart Grid of Ministry of Education School of Electrical and Information Engineering Tianjin University Tianjin300072 China School of Semiconductor and Physics North University of China Taiyuan030051 China Engineering Research Center of High Power Solid State Lighting Application System Ministry of Education Tiangong University Tianjin300387 China School of Physical Science and Technology Tiangong University Tianjin300387 China

The high-pressure electronic structure and electrical properties of Mg2Pb are investigated from ambient pressure to 42 GPa by first-principles calculation. Mg2Pb undergoes reversible structural transitions from Fm-3m structure to Pnma structure and then to P63/mmc structure. The structural phase transitions are determined respectively at around 6 GPa and 28 GPa using pressure-dependent enthalpy calculations, which are also reflected from the cell volume collapse and discontinuous axial ratios of lattice constants. The sliding of Mg and Pb atomic layers is revealed via the Mg1-Pb-Mg2 atom pair during structural phase transitions, corresponding to abrupt decrease of c/b and a/b. The semimetal-to-metal transition is also observed at approximately 28 GPa owing to energy-band closure, whilst metallic character is strengthened with increasing pressure. The paper is prone to explore the structural phase transition and metallization of Mg2Pb-type family in theory under extreme conditions. © 2023, The Authors. All rights reserved.

关键词： Electronic structure

Pressure-Dependent Compressibility of K2x(Co3)2 (X=Ca, Mg) Under High Pressure

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SSRN 2023年

作者： Tian, Haitao Li, Yuhong Zhang, Qiang Su, Ningning Sun, Jinlu Xiao, Ningru Liu, Yuyao Zhang, Jianxin Liu, Hongwei Li, Yuqiang Tianjin Key Laboratory of Optoelectronic Detection Technology and Systems School of Electronics and Information Engineering Tiangong University Tianjin300387 China Key Laboratory of Smart Grid of Ministry of Education School of Electrical and Information Engineering Tianjin University Tianjin300072 China School of Semiconductor and Physics North University of China Taiyuan030051 China Engineering Research Center of High Power Solid State Lighting Application System of Ministry of Education Tiangong University Tianjin300387 China School of Physical Science and Technology Tiangong University Tianjin300387 China

The high-pressure phase transition behaviors and pressure-dependent compressibility are investigated on K2X(CO3)2 using first-principles calculation from ambient pressure to 30 GPa. The reversible structural phase transitions of K2X(CO3)2 are determined based on enthalpy difference and cell volume collapses. The pressure point of structural phase transitions of K2Ca(CO3)2 is obtained at around 3.3 GPa and 10.3 GPa, while that is found at about 6.2 GPa and 22.6 GPa for K2Mg(CO3)2. Compared with the high axial rigidity of C-O bonds in [CO3] groups, the Ca+ and Mg+ coordination polyhedron show much more compressible. The displacement behavior of the Ca+ and Mg+ coordination polyhedron occurs simultaneously with the rotation behavior of [CO3] groups during compression, and reverses induced by the structural phase transition. © 2023, The Authors. All rights reserved.

关键词： Crystal structure

Structural And Electronic Properties Of Weyl Semimetal Wte2 Under High Pressure

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SSRN 2023年

作者： Li, Yuqiang Li, Yuhong Zhang, Qiang Liu, Xiaofeng Xiao, Ningru Ning, Pingfan Wang, Jingjing Liu, Yang Zhang, Jianxin Liu, Hongwei Tianjin Key Laboratory of Optoelectronic Detection Technology and Systems School of Electronic and Information Engineering Tiangong University Tianjin300387 China Key Laboratory of Smart Grid Ministry of Education School of Electrical and Information Engineering Tianjin University Tianjin300072 China Tianjin San’an Optoelectronics Co. Ltd. Tianjin300384 China Engineering Research Center of High Power Solid State Lighting Application System Ministry of Education Tiangong University Tianjin300387 China School of Physical Science and Technology Tiangong University Tianjin300387 China

The structural and electronic properties of WTe2 are studied from ambient pressure to 30.0 GPa. The pressure-induced structural phase transition is found from Td phase (Pnm21, No. 31) to 1T′ phase (P21/m, No. 11) above 10.0 GPa by lattice offset, which is also reflected at approximately 11.2 GPa based on the discontinuous electrical parameters. A pair of hole wave and electron wave packets of Td phase gradually overlap revealing the reversible Td-to-1T′ phase structural transition. WTe2 is observed to undergo semimetal-to-semiconductor transition owing to the calculated energy band up to 15 GPa, which is also observed at 11.2 GPa according to the resistivity-temperature curves under compression and decompression conditions. The electronic density of states at the Fermi level is mainly contributed by the d orbital of W and the p and s orbital of Te. The photoconductivity property is shown by the theoretical and experimental methods. © 2023, The Authors. All rights reserved.

关键词： Electronic properties

First-Principles Study of Electronic Structure and Metallization of Xpse3 (X=Fe, Mn) Under High Pressure

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SSRN 2023年

作者： Li, Yuqiang Li, Yuhong Zhang, Qiang Su, Ningning Sun, Jinlu Xiao, Ningru Liu, Yang Liu, Yuyao Zhang, Jianxin Liu, Hongwei Tianjin Key Laboratory of Optoelectronic Detection Technology and Systems School of Electronics and Information Engineering Tiangong University Tianjin300387 China Key Laboratory of Smart Grid of Ministry of Education School of Electrical and Information Engineering Tianjin University Tianjin300072 China School of Semiconductor and Physics North University of China Taiyuan030051 China Engineering Research Center of High Power Solid State Lighting Application System of Ministry of Education Tiangong University Tianjin300387 China School of Physical Science and Technology Tiangong University Tianjin300387 China

The pressure-induced structural phase transition and metallization of FePSe3 and MnPSe3 are investigated from ambient pressure to 40 GPa by first-principles calculation. FePSe3 and MnPSe3 undergo reversible structural transitions from R-3 structure to C2/m structure and then to P-31m structure. The structural phase transitions of FePSe3 are at about 6 GPa and 13 GPa, while the pressure points are at approximately 13 GPa and 25 GPa for MnPSe3, reflecting from pressure-dependent enthalpy calculation, cell volume collapses, and sudden changes of lattice parameters. The computed metallization transition is also observed at around 8 GPa and 16 GPa owing to energy-band closure for FePSe3 and MnPSe3, respectively. The metallic character of XPSe3 is strengthened with increasing pressure based on the electronic energy band and electron density of states. The layer sliding of atoms is revealed using the P2-P3 atom pair of XPSe3 during structural phase transitions. The paper is conducive to considering the electronic structure and metallization of transition metal thiophosphates XPSe3-type family under extreme conditions. © 2023, The Authors. All rights reserved.

关键词： Electronic structure

Excellent electrical properties of zinc-oxide varistors by tailoring sintering process for optimizing line-arrester configuration 7

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Excellent electrical properties of zinc-oxide varistors by t...

7th IEEE International Conference on High Voltage Engineering and Application, ICHVE 2020

作者： Meng, Pengfei Cao, Wei Chen, Chao Wan, Shuai Xu, Heng Hu, Jun He, Jinliang Tsinghua University Department of Electrical Engineering Beijing China Wuhan Nari Limited Liability Company State Grid Electric Power Research Institute Wuhan China Guangdong Aikang Electric Power Co. Ltd Guangzhou China State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Department of Electrical Engineering Beijing China

ISBN: (纸本)9781728155111

We optimized the excellent electrical performance of zinc-oxide (ZnO) varistors doping of aluminum and indium by tailoring the sintering process. The surface morphology, nonlinear volt ampere properties, capacitance-voltage characteristics, and dielectric analyses were carried out. At a given aluminum and indium concentration, the average sample grain size (d) increased as lengthening sintering time from 0.5 to 2.5 h. The voltage gradient (E_{1\{mA}}) decreased from 602.4 V/mm to 356.7 V/mm. The residual voltage of the sintered varistors at the lightning impulse current (8/20\ \mu\mathrm{s}) decreased as the samples sintering holding time extended from 0.5 to 2.0 h. When the ZnO varistor was sintered for 1.5 h, the samples showed an excellent performance, with a reference voltage of 479.3 V/mm at 1 mA DC. When assembled in the line surge arresters, the obtained high-voltage-gradient ZnO varistors can decrease their length and residual voltage, which allows for better coordination of the line surge arrester with the insulators. This study has great significance to optimize line-arrester configurations and improve power-system stability. © 2020 IEEE.

关键词： Sintering

A Novel Method of power Swing Blocking in Impedance Relay 8

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A Novel Method of Power Swing Blocking in Impedance Relay

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