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A Synchronization Algorithm for Burst-Mode MR-OFDM System of 802.15.4g

Journal of Physics: Conference Series 2019年第1期1325卷

作者： Yahong Zhao Xu Zhao Yubing Zhang Xiaoke Tang Mingke Dong State Grid Key Laboratory of Power Industrial Chip Design and Analysis Technology Beijing Smart-Chip Design and Analysis Technology Co. Ltd Beijing Beijing 100192 China School of Electronics Engineering and Computer Science Peking University Beijing Beijing 100871 China

This paper presents a refined coarse frame synchronization algorithm for long repeated-sequence based preamble STF (short training field) in burst mode MR-OFDM system of 802.15.4g which is of low decision delay and resistant to timing uncertainty due to metric plateau. The precision of coarse timing and frequency offset estimation is improved. A fine symbol timing and frequency offset estimation algorithm based on LTF (long training field) is also proposed which provides an overall solution for the synchronization of burst mode MR-OFDM system. Simulation results are given to provide reference for implementation.

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Distance protection operation characteristics analysis of the AC/DC system based on MMC-HVDC interconnection

Distance protection operation characteristics analysis of th...

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第二届机电控制技术与交通运输国际学术会议(ICECTT 2017)

作者： Maolin Tang Rui Yu Xi Zhang Chao Xiao Jinxin Ouyang Xiaofu Xiong State Grid Southwest Division State Key Laboratory of Power Transmission Equipment and System Security and New Technology Chongqing University

With the attractive advantages of high stability and controUabihty,the MMC-HVDC system has become a key development direction for the *** operation and controllability features of the MMC-HVDC system differ significantly from those of conventional AC and DC *** the grid fault,the MMC-HVDC system exports various short-circuit currents to the AC system,which can be a threat to the correct operation of distance *** the basis of the control principle of the MMC-HVDC converter station,the voltage and phase features of the MMC-HVDC short-circuit current are *** measured impedance variation of the MMC-HVDC distance protection in the AC side is also *** influence and interrelated factors of the MMC-HVDC system to distance protection are *** simulation of PSCAD/EMTDC is done to verify the validity of the analysis.

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Research on Parallel Operation Control of Modules Based on Common DC Bus

Research on Parallel Operation Control of Modules Based on C...

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China International Electrical and Energy Conference (CIEEC)

作者： Mingqing CHEN Guangyao QIAO Xuan WANG Liang ZHANG Ying ZHANG Bin ZHU Feng DAN State Key Laboratory of Advanced Power Transmission Technology/Global Energy Interconnect Research Institute Co. Ltd. Beijing China China EPRI Science & Technology Co. Ltd. Beijing China National Active Distribution Network Technology Research Center(NANTEC) Beijing Jiaotong University Beijing China State Grid Chongqing Electric Power Research Institute Chongqing China Electricity Affair Engineering Company of China Rarway NO.8 Engineering Group Co. Ltd. Sichuan China

ISBN: (纸本)9781538653937

Electric vehicles are the new energy vehicles with the least exhaust emissions. Therefore, the development of electric vehicles has been valued by many countries. The charging station is the energy supply center for electric vehicles. Whether the charging station is built well determines the degree of popularization of electric vehicles. This paper studied the parallel operation control of modules which are based on the common DC bus in charging station. In the vehicle-to-grid (V2G) mode, when the output sides of the rectifier modules are connected in parallel, all DC/DC charging modules will supply power to the DC bus. Whether the modules can achieve current-sharing is a key factor that affects the reliable operation of the system. The I/U droop control is utilized to achieve current-sharing of all the parallel modules. Consequently, the complicated and less reliable high-speed communication can be eliminated, which improved the system reliability greatly. Simulation in MATLAB verified the feasibility of the strategy.

关键词： Topology Vehicle-to-grid Charging stations Batteries Voltage control

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Arc separating process experiment study in low voltage circuit breaker 6

Arc separating process experiment study in low voltage circu...

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6th International Conference on Reliability of Electrical Products and Electrical Contacts, ICREPEC 2017

作者： Zhu, Tiansheng Liu, Hongwu Guan, Ruiliang Chen, Huiling State key laboratory of Electrical Insulation and Power Equipment Xi'an Jiaotong University Xi'an710049 China Changshu Switchgear Mfg. Co. Ltd. Changshu Switchgear Plant Jiangsu Key Laboratory of Smart Grid Distribution and Utilization Technology Research Changshu215500 China

ISBN: (纸本)9789881532398

Weather the arc is separated by the deion plates or not will determine success or failure of interruption for current-limiting circuit breaker. So it's important to investigate the separating condition of arc by the splitters. In this study the oscillating circuit is used as supply power. For circuit breaker with 250A frame size, different materials and numbers of splitters are tested in short current interrupting process. Experiment results verified the necessary condition of successful arc separating process. While the arc column voltage is higher than total voltage of separated arc, the arc will be possibly separated. With the increase of splitters number the required current is higher while the other parameters are constant. Larger number of splitters means higher corresponding arc voltage, which may more easily cause back strike.

关键词： Electric circuit breakers

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Three-phase Analytical Optimization Algorithm for Sectionalizing Switch Placement of a Medium Voltage Overhead Line

Three-phase Analytical Optimization Algorithm for Sectionali...

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2017 2nd International Seminar on Applied Physics,Optoelectronics and Photonics（APOP 2017）

作者： Yi-xi LIAO Xuan LUO Bo JIANG Mitchell WANG State Key Laboratory of Power Transmission Equipment & System Security and New Technology Chongqing University State Grid Shanxi Electric Power Company Economic and Technological Research Institute State Grid Shanxi Electric Power Company

In the paper,a new heuristic algorithm is proposed for the sectionalizing switch placement of medium voltage overhead lines whose switches are of the same *** objective function includes the reliability indexes of system average interruption duration(SAIDI) and expected energy not supplied(EENS).The constraints involve the maximum available investment,user reliability requirement and maximum sectionalizing switch number,etc.A general maximum product criterion of benefitted load and isolated line length,is presented to locate a single switch,and a three-phase analytical optimization algorithm is proposed for the sectionalizing switch placement of a medium voltage overhead line.A case study shows the effectiveness and practicability of the proposed analytical model and algorithm.

关键词： Three-phase Analytical Optimization Algorithm for Sectionalizing Switch Placement of a Medium Voltage Overhead Line

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Time and Space Distribution Prediction of Electric Vehicle Charging Load Based on Statistical Analysis

Time and Space Distribution Prediction of Electric Vehicle C...

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2017 2nd International Conference on Computer, Mechatronics and Electronic Engineering(CMEE 2017)

作者： Long-chang DONG Min-you CHEN Jun-jie LI Ying-xiang WANG State Key Laboratory of Power Transmission Equipment & System Security and New Technology Chongqing University State Grid Chongqing Electric Power Research Institute

The electric vehicle charging load forecasting is influenced by many factors and full of randomness and complexity based on the charging operation history data and according to the different types of charging power of different charging behavior, we propose Monte Carlo simulation calculation method which extracts the initial state of charge and the start time of charging. The behavior of different charging methods and different vehicles are classified according to the charging requirements, we selected the starting time and duration of charging as the key factors affecting the charging load time distribution, combined with the statistical analysis of users' charging behavior, to establish the charging load time distribution model. On this basis, we divided the charging load areas to establish the time and space distribution model of charging load. Through the examples analysis,we predicted the temporal and spatial distribution of the load level of the electric vehicle in Chongqing. The analysis results show that with the development of electric vehicle in Chongqing, the charging load will have great influence on the operation and planning of power grid. The charging load has obvious peak to valley difference, and the potential of load regulation is great.

关键词： Electric vehicle Statistical analysis Monte Carlo simulation Temporal and spatial distribution

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Research on erosion rate of contacts for MCCB in short circuit conditions 6

Research on erosion rate of contacts for MCCB in short circu...

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6th International Conference on Reliability of Electrical Products and Electrical Contacts, ICREPEC 2017

作者： Yin, Nairui Liu, Hongwu Guan, Ruiliang Xie, Xinyi State key laboratory of Electrical Insulation and Power Equipment Xi'an Jiaotong University Xi'an71004 China Changshu Switchgear Mfg. Co. Ltd. Changshu Switchgear Plant Jiangsu Key Laboratory of Smart Grid Distribution and Utilization Technology Research Changshu215500 China

ISBN: (纸本)9789881532398

In this study the oscillating circuit is set up as power supply. With different circuit parameters a certain type of MCCB is tested to simulate short circuit breaking process. By using split electrode method, the current flowing through the static contact is measured in interrupting process. 3-D scanning technology is used to achieve the morphology and erosion volume of contacts after several times of short current interruption. According to experiment results, time integral of the current flowing through the static contact is proportional to erosion volume of static contact. Erosion volume of moving contact increases with higher time integral of the arcing current. Because distribution of arc root on the surfaces of moving contact and nearby conductor is affected by magnitude of short current, erosion volume of moving contact and time integral of the arcing current aren't linear relations. According to above conclusions, it's very important to improve mobility of arc root on the surface of static contact for decreasing contact erosion in short circuit breaking process.

关键词： Erosion

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High-accurate estimation method of sub-synchronous and super-synchronous harmonic parameters on PMU

High-accurate estimation method of sub-synchronous and super...

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6th International Conference on Renewable power Generation

作者： Tan, Yong Chen, Rong Wang, Meng Zhang, Min Hou, Mingguo NARI Group Corporation State Grid Electric Power Research Institute Nanjing21106 China NARI Technology Development Co. Ltd. Nanjing211061 China State Key Laboratory of Smart Grid Protection and Control Nanjing210061 China School of Rail Transportation Soochow University Suzhou215131 China

With the rapid development of renewable energy power generations, AC/DC transmissions and static compensations etc., power electronic technology has been widely applied in power system. As traditional power equipment is replaced by a large number of power electronic devices, the disturbances such as harmonic interference and sub-synchronous oscillation are more frequently. In order to detect the subsynchronous oscillation in power system in time, and take measures to ensure the safety and stability of power system, this article analyses the algorithm principle of the phasor measurement unit (PMU) and the communication architecture of wide area measurement system (WAMS)/ PMU system. According to the IEEE Std C37.118-2011 standard, it elaborates the problems and the limitations existing in the monitoring of sub-synchronous and super-synchronous harmonic parameters on WAMS. On the basis of the above, a method of online identification and alarm for the sub-synchronous and super-synchronous harmonic parameters on PMU device is proposed. Combined with the fast Fourier transform spectrum correction theory, the high-accuracy identification method of distributed sub-synchronous and super-synchronous harmonic parameter is realised. The feasibility and accuracy of the method is verified by simulation experiments. © 2017 Institution of Engineering and technology. All Rights Reserved.

关键词： Fast Fourier transforms

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Constructing spherical Ziegler-Natta catalyst through an emulsion process for ethylene polymerization

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AIP Conference Proceedings 2019年第1期2154卷

作者： Zhaoliang Xing Chong Zhang He Huang Hui Liu Xiangyu Zhang Yu Xiao Yinghao Qi Tao Jiang Jian Li 1State Key laboratory of Advanced Transmission Technology Global Energy Interconnection Research Institute Co. Ltd. Beijing 102209 China 2State Grid Shanxi Electric Power Company Economic and Technological Research Institute Taiyuan 030001 China 3College of Chemical Engineering and Material Science Tianjin University of Science and Technology Tianjin 300457 P. R. China

The article describes morphology studies on a solid MgCl2−based TiCl4 Ziegler-Natta catalyst for ethylene polymerization prepared via emulsion technique. Scanning electron microscopy (SEM) measurements revealed spherical catalyst particles with controllable diameter. The presenting of surfactant showed significantly influence on the morphology and particle diameter distribution of particles. The slurry polymerization of ethylene was studied with this catalyst system. The results showed that the catalyst had high activity and sensitive hydrogen responsibility. Polyethylene has good grain morphology because of duplicating the spherical morphology of the catalyst.

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The analysis of distance protection operation characteristics of power system based on VSC-HVDC interconnection

The analysis of distance protection operation characteristic...

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

作者： Maolin Tang Chao Xiao Jinxin Ouyang Rui Yu Xi Zhang Xiaofu Xiong Yongjie Luo State Grid Southwest Division Chengdu China State Key Laboratory of Power Transmission Equipment & System Security and New Technology Chongqing University Chongqing China

ISBN: (纸本)9781538614280

As the VSC-HVDC system has attractive advantages of high stability and controllability, it becomes a key development direction of the HVDC. Dynamic operation and controllability features of VSC-HVDC system differ a lot from that of conventional AC and DC transmission. During the grid fault, the VSC-HVDC export various short circuit current to AC system which can be a threat to the correct operation of distance protection. Based on the control principle of VSC-HVDC converter station, the voltage and phase features of the VSC-HVDC short-circuit current is analyzed. The measured impedance variation of the VSC-HVDC distance protection in AC side is also analyzed. The influence and interrelated factors of VSC-HVDC to distance protection are proposed. Digital simulation on PSCAD/EMTDC is done to verify the validity of the analysis.

关键词： power conversion Circuit faults Short-circuit currents Impedance Impedance measurement transmission line measurements

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