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作者： Wang, Bin Yang, Lin Dong, Xinzhou Department of Electrical Engineering State Key Lab of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing10084 China

The reflection coefficient of the travelling wave is different with different frequencies because of the inductance and capacitive elements on the boundary of the DC transmission line, which leads to the oscillation of the travelling wave. It is difficult to obtain the wave head's arrival time accurately using travelling wave method to locate fault because of the oscillation. The current travelling wave is the superposition of the incident current travelling wave and the reflected current travelling wave. There is no oscillation in the incident wave. Therefore, a method using incident current wave for fault location is proposed here. The initial current travelling wave and the transmission line boundary function are used to calculate the incident current travelling wave, and the incident wave is used to locate fault. The Prony decomposition algorithm is used to identify boundary function using the initial current travelling wave generated in specific fault condition. PSCAD simulation shows that the influence of oscillations of travelling wave can be eliminated by using incident current wave to locate faults, and the accuracy of fault location is improved. © Institution of Engineering and Technology. All rights reserved.

关键词： Electric lines

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An Improved Master-Slave control for Three-port Converter Based Distributed DC Grid-connected PV System 8

An Improved Master-Slave Control for Three-port Converter Ba...

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8th International power Electronics Conference, IPEC-Niigata - ECCE Asia 2018

作者： Jiang, Siyue Sun, Kai Wu, Hongfei Shi, Haixu Dong, Xiaofeng Raza Kazmi, Syed Muhammad State Key Lab of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing China Jiangsu Key-Laboratory of New Energy Generation and Power Conversion Nanjing University of Aeronautics and Astronautics Nanjing Jiangsu Province China United States Pakistan Center for Advanced Studies in Energy National University of Sciences and Technology Islamabad Pakistan

ISBN: (纸本)9784886864055

With the development of DC grid technology, it has become a trend to introduce photovoltaic(PV) as a power source to the DC power distribution network. In this paper, an improved master-slave control strategy is proposed to realize power splitting and voltage sharing in a modular system with PV connected. Each module is a three-port converter: Input port connects distributed PV, output port connects to DC grid, and intermediate port is connected in parallel with other modules as a bus to realize the power splitting. For a single module, input voltage, intermediate bus voltage and output voltage should all be controlled to reference but only duty ratio and phase-shifting angel can be regulated hence it may occur the multi-objective variables control problem. While using the proposed strategy, this problem can be solved effectively and the system stability is ensured during the voltage sharing process. This control strategy is verified by simulation and experiment. © 2018 IEEJ Industry Application Society.

关键词： System stability

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Study on transferred lightning overvoltage in microgrid

Study on transferred lightning overvoltage in microgrid

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Asia-Pacific International Symposium on Electromagnetic Compatibility

作者： Hongqiao Yu Shuiming Chen Pengcheng Yang State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University

ISBN: (纸本)9781424456215

If the microgrid is stroke by lightning, the lightning overvoltage which transferred though distribution transformer has great influence on the safety of the microgrid. The models of microgrid and high-frequency transformers are established based on the electromagnetic transient calculation program PSCAD/EMTDC. The transferred overvoltage with different lightning strike position in microgrid is researched in this paper. The effect of surge arresters on restricting overvoltage is also analyzed. The simulation results show that surge arresters must be installed at both sides of transformer due to the high overvoltage when the transformer has no load. If the transformer is connected with cables, the overvoltage will be reduced. The longer the cable is, the lower the overvoltage is. The types of loads have a little influence on the overvoltage.

关键词： Lightning Voltage control power transformer insulation Frequency Capacitance Laboratories power system simulation power system modeling power generation Electromagnetic modeling

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Design Optimization of Ferrite Rings for VFTO Mitigation

Design Optimization of Ferrite Rings for VFTO Mitigation

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作者： He, Jiaxi Guan, Yonggang Liu, Weidong Chen, Weijiang Li, Zhibing The Department of Electrical Engineering State Key Lab of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing100084 China State Grid Corporation of China Beijing100031 China China Electric Power Research Institute Beijing100192 China

very-fast transient overvoltage (VFTO)-related problems are raising growing concerns in China with the development of ultra-high voltage. The practice of fitting ferrite rings on gas-insulated switchgear busbars for VFTO mitigation has long been proposed but few investigations on its design optimization were conducted. Based on theoretical analysis of the simplified model, the optimal damping condition of ferrite rings is proposed, which is conducive to the type selection. The number of rings to be employed to ensure visible suppressing effects is given through simulations and the influence of the saturation is discussed. Impact on the power frequency is analyzed to be negligible. Finally, comparisons are made between the theoretical conclusions and existing experiment results, which approve the optimal damping condition and agree with the number of rings to be employed. © 2014 IEEE.

关键词： Damping

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Digital power system

Digital power system

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World Congress on Intelligent control and Automation (WCICA)

作者： Lu Qiang State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments China

The concept of a digital power system (DPS) is set forth in the paper. The definition, the contents, the function, the hardware and the software conditions for implementing it are discussed. Moreover, the necessary basic research work for implementing a DPS is also discussed. The DPS may be defined like this: the digital power system is the digital, figuration and real time description and reappearance of physical structure, technical characteristic, management system as well as personal information system of a real power system which is in operation. The DPS will be able to make a significant contribution to administrating and decision-making more scientifically, improving security and stability online, online making and implementing economical operation strategy and carrying out emergency and anti-fault control, etc.

关键词： power system control

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Vector control for a twelve-phase synchronous motor

Vector control for a twelve-phase synchronous motor

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International Conference on Electrical Machines and systems (ICEMS)

作者： Dejia Zhou Zhengming Zhao Shanming Wang Jianyun Chai State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering and Applied Electronic Technology Tsinghua University Beijing 100084 China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing China

A twelve-phase synchronous motor with four Y-connected 3-phase symmetrical windings displaced in turn by 15deg is modeled by using flux linkages as state variables, and an optimized method for the vector control is proposed with the simulation results. The observing model for magnetizing flux linkage at the direct-axis is derived whereby a vector control scheme of a twelve-phase synchronous motor, and related simulation is constructed in this paper. Using switch blocks to model the functions of twelve-phase voltage-fed inverter is convenient for simulating the driving system. The results of the simulations show that the torque and magnetizing flux linkage can be controlled separately, and the dynamic characteristics of the motor are satisfied with the operating requirements.

关键词： Machine vector control Synchronous motors Couplings Magnetic separation Magnetic flux Switches Optimization methods Voltage Inverters Torque control

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Instantaneous energy balancing in three-level neutral point clamped converters

Instantaneous energy balancing in three-level neutral point ...

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IEEE Conference on Vehicle power and Propulsion (VPPC)

作者： Lu Ting Zhengming Zhao Liqiang Yuan Shuping Wang State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China. State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China

Instantaneous energy balancing plays an important role in power electronics conversion. The unbalance of electromagnetic energy not only debases the system performance but also decreases the reliability and efficiency of the conversion. In this paper, instantaneous energy balancing problems in three-level neutral point clamped (NPC) converters are classified and discussed. Typical examples and their usual solutions of each kind of problems are expounded and compared. In the end of this paper, limitations and disadvantages of traditional methods are analyzed, and electromagnetic field method is summarized as the new trend to analyze electromagnetic energy transmission and exchange. The method using electromagnetic field theory is emphasized to be the better approach to solve the aforementioned energy balancing problems.

关键词： Voltage control Capacitors Open loop systems Pulse width modulation converters power electronics Energy storage Switching converters power system simulation power system reliability Electromagnetic analysis

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Principle and Model for Regional Allocation of Carbon Emission from Electricity Sector

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Electricity 2012年第4期23卷 52-53页

作者： Li Baowei Hu Zechun Song Yonghua Wang Guanghui State Key Lab of Control and Simulation of Power Systems and Generation Equipment Dept. of Electrical Engineering Tsinghua University

The paper “Principle and Model for Regional Allocation of Carbon Emission from Electricity Sector” is focused on the hot issue of carbon allocation problem,while the research scope is restricted to electricity *** authors propose a fair allocation principle considering the social contribution and environmental cost of electricity *** to the allocation principle,a novel model and concept of carbon flow tracing is presented to satisfy the requirements based on electricity flow tracing methodology,which traces the sources of regional electricity imports to determine the carbon allocation reasonably.

关键词：分配原则电力行业碳排放跟踪方法分配问题电力部门电力供应碳分配

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Wide-area Monitoring and Analysis of Wide-band Oscillation in New-type power systems 10

Wide-area Monitoring and Analysis of Wide-band Oscillation i...

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10th China International Conference on Electricity Distribution, CICED 2022

作者： Ma, Ningning Xie, Xiaorong Sun, Yiqian Zhang, Yanjun Li, Yongguang Liu, Pengyin State Key Lab of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua University Haidian District Beijing100084 China State Grid Xinjiang Electric Power Company Xinjiang Uygur Autonomous Region Urumchi830063 China

ISBN: (数字)9781665452687

ISBN: (纸本)9781665452687

The wide-band oscillation resulting from the interaction between power electronics and the power grid is increasingly evident to the power system. It is necessary to monitor the dynamic behavior of the wide-band oscillation. However, the existing phasor measurement unit (PMU) and the corresponding wide-area measurement system (WAMS) can hardly capture wide-band phasors. To get a better view of wide-band oscillation, a measurement method to capture wide-band phasors is proposed in this paper, as well as a frame of a corresponding wide-area monitoring system for wide-band oscillation (WOMS) is constructed. The prototype of the wide-band phasor measurement unit (WPMU)-based on this measurement method is developed. The essential software and hardware of the WPMU are elaborated. The steady tests and dynamic tests are executed to verify the capability of the WPMU. The results indicate that WPMU and WOMS are highly effective in analyzing wide-band oscillation. © 2022 IEEE.

关键词： Phasor measurement units

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Study on lightning protection of cables and transformer in Microgrid

Study on lightning protection of cables and transformer in M...

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China International Conference on Electricity Distribution, CICED

作者： Hong-qiao Yu Shui-ming Chen Yang Peng-cheng State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing 100084 China

ISBN: (纸本)9781457700668

The cable and transformer are important distribution equipment in Microgrid. Due to the low insulation level, the insulation of them is easily damaged by lightning. The models of high-frequency transformer and the calculation model of induced lightning with transmission line based on electromagnetic transient calculation software PSCAD / EMTDC are designed in this paper. The lightning protection of cables and transformer in Microgrid, the transferred overvoltage of transformer and the effect of the length of cables and the load types to overvoltage level are researched. The conclusion shows that the induced overvoltage and transferred overvoltage could be reduced efficiently after installing surge arrester at the cables and transformer, but the direct lightning overvoltage is not reduced in the safety range; The longer the cables, the lower the overvoltage is; The inductively load can reduce the overvoltage level slightly while the capacitive and resistance loads has no influence.

关键词： power cables Load modeling Arresters Cable insulation EMTDC Lead PSCAD

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