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International Symposium on Discharges and Electrical Insulation in Vacuum

作者： Haonan Yang Shuhang Shen Zhongdong Wang Ruoyu Xu Mingyu Zhou Centre for Smart Grid University of Exeter Exeter UK Global Energy Interconnection Research Institute Europe GmbH Berlin Germany State Key Laboratory of Advanced Power Transmission Technology Beijing China

In vacuum arcing, contact erosion is closely related to the cathode spot dynamics. It is commonly accepted that the ions from leftover plasma and metal vapor ionization are the main sources of bombardment. In this paper, the process of ion bombardment (IB) on a cold cathode is simulated by the Molecular Dynamics (MD) method. The model is composed of a copper substrate and the inserted copper ions, whose energy is calculated according to the theory of the surface layer. To investigate the effects of ion energy and ion current density distribution on the process of IB, three types of simulation, including single IB, continuous IB at one site, and regional continuous IB, are conducted. From the simulation results, the mechanism of crater formation is proposed. It’s found that the pressure effect of IB is mutually decided by the ion energy and the local surface temperature, the latter of which is controlled by the ion current density. This work also provides a possible explanation on various sizes of the cathode spot measured in the experiments.

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μ Analysis on the dc-Link Voltage Control Stability of the Weak-grid-Connected VSC

μ Analysis on the DC-Link Voltage Control Stability of the ...

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Power Science and technology (ICPST), IEEE International Conference on

作者： Yong Chen Xu Cheng Jianfu Chen Li Zhang Xiaoyan Zhao Xin Jin Zhuhai Power Supply Bureau/DC Power Distribution and Consumption Technology Research Center Guangdong Power Grid Co. Ltd. Zhuhai China Zhuhai Power Supply Bureau Guangdong Power Grid Co. Ltd. Zhuhai China Ruili Power Supply Bureau Yunnan Power Grid Co. Ltd. Ruili China State Key Laboratory of Internet of Things for Smart City University of Macau Macao SAR China

ISBN: (数字)9798350349030

ISBN: (纸本)9798350349047

Uncertainties accompany practical system inherently complicate the stability analysis for the weak-grid-connected voltage source converter (VSC) under dc-link voltage control (DVC). In this paper, structured singular value (SSV, also called μ)-based approach is proposed to explore the stability region of this (multi-input-multi-output) MIMO system considering parametric uncertainties. First, system small-signal model is established, and the generalized uncertain model is formulated using linear fractional transformation (LFT) algorithm. Then, system stability boundary is determined by the comparison between the value of μ and the criterion, under multiple parametric perturbations. Finally, eigenvalues analysis and time-domain simulation results validate the predictions accuracy of the proposed μ approach.

关键词： Uncertainty Sensitivity simulation Stability criteria Power system stability Eigenvalues and eigenfunctions Voltage control

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Research on Optimal Allocation of Network Loss for Centralized Renewable Energy Plants

Research on Optimal Allocation of Network Loss for Centraliz...

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IEEE Asia Power and Energy Engineering Conference (APEEC)

作者： Wenxuan Tong Zhengang Lu Minxiao Han Guoliang Zhao Jufeng Li Fangyang Chai School of Electrical and Electronic Engineering North China Electric Power University Beijing China State Key Laboratory of Advanced Power Transmission Technology State Grid Smart Grid Research Institute Co. Ltd. Beijing China State Key Laboratory of Alternate Electrical Power System With Renewable Energy Sources North China Electric Power University Beijing China North China University of Technology Beijing Engineering Research Center of Frequency Conversion Technology Beijing China

Hybrid Power Station (HPS) will be one of the primary forms of the future power station to construct a safe and stable renewable power system. Due to the uneven regional spread of renewable energy resources, large-scale centralized development will become essential for renewable energy utilization. In this study, we investigate the optimal siting of HPS from the perspective of network loss optimization. First, we establish the basic model of network loss and propose this study's three basic assumptions through a three-bus radial network case study. Subsequently, to solve the optimal siting problem of centralized HPS, we propose a centralized HPS siting optimization method (CAM) and give a detailed application flowchart. Finally, we build an IEEE 14-bus model based on the MATLAB/Simulink platform to simulate and validate the CAM method and visualize the simulation data based on the IEEE 14-bus schematic, and the results obtained verify the effectiveness of the CAM method.

关键词： Electrical engineering Renewable energy sources Flowcharts Optimization methods Mathematical models Data models Hybrid power systems

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Inertial characteristics of gravity energy storage systems

Inertial characteristics of gravity energy storage systems

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IEEE PES Asia-Pacific Power and Energy Engineering Conference (APPEEC)

作者： Wenxuan Tong Zhengang Lu Minxiao Han Haisen Zhao Guizhi Xu Guoliang Zhao Julian David Hunt State Key Laboratory of Advanced Power Transmission Technology State Grid Smart Grid Research Institute Co. Ltd. Beijing China School of Electrical and Electronic Engineering North China Electric Power University Beijing China Center for Desert Agriculture Biological and Environmental Science and Engineering Division King Abdullah University of Science and Technology Thuwal Saudi Arabia

ISBN: (数字)9798350318098

ISBN: (纸本)9798350318104

Gravity energy storage is a technology that utilizes gravitational potential energy for storing and releasing energy, which can provide adequate inertial support for power systems and solve the problem of the volatility and intermittency of renewable energy generation. The inertial features of gravity energy storage technology are examined in this work, including the components of inertial support, directionality, volume, and adjustability. This paper establishes a mathematical model of the gravity energy storage system. It derives its expression of inertia during grid-connected operation, revealing that the inertial support consists of two components: the rotational kinetic energy of the motor rotor and the operational kinetic energy of the mass. This paper analyzes the inertia support characteristics of the mass and finds that it has the characteristics of single-directional, auxiliary frequency modulation and is not affected by transmission equipment, proving that the inertia support of the mass is equal to the amount of its running kinetic energy change. Finally, this paper verifies the inertia characteristics of gravity energy storage by establishing a microgrid simulation model based on MATLAB/Simulink.

关键词： Frequency modulation Rotors Microgrids Wind power generation Motors Mathematical models Power systems

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An improved voltage prediction criterion of commutation failure in HVdc

An improved voltage prediction criterion of commutation fail...

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2020 IEEE Power and Energy Society General Meeting, PESGM 2020

作者： Zeng, Yuan Li, Yan Lu, Yajun Wei, Wei Zhang, Yunxiao Liu, Xinyang Tianjin University Key Laboratory of Smart Grid of Ministry of Education Tianjin China Research Institute DC Technology Center State Power Economic Beijing China DC Technology Center State Grid Corporation of China Beijing China

ISBN: (纸本)9781728155081

Aiming at the problem of commutation failure often occurring in high voltage direct current (HVdc), the shortcoming of the existing voltage prediction criterion is analyzed based on the mechanism of commutation failure. By building the HVdc model and studying the transient process of HVdc after three-phase AC fault, a time-series segmentation method is proposed to calculate the post-fault transient dc current based on the post-fault AC voltage. Based on the method, an improved voltage prediction criterion of commutation failure simultaneously considering the dc current dynamics and the pre-fault operating state of HVdc is proposed, which can improve the accuracy of commutation failure prediction significantly. The feasibility and validity of the proposed current calculation method and improved voltage prediction criterion are verified by the comparison with the simulation results. © 2020 IEEE.

关键词： Time series

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dc fault ride-through for wind power integration via MMC-HVdc based on precise control of energy storage configured inside wind farm

DC fault ride-through for wind power integration via MMC-HVD...

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Renewable Power Generation and Future Power Systems Conference 2023 (RPG 2023 UK)

作者： Y. Sun Y. Guo F. Fan J. Fan G. Li Z. Wang X. Wu Key Laboratory of Modern Power System Simulation and Control & Renewable Energy Technology Ministry of Education (Northeast Electric Power University) Jilin People's Republic of China School of Electrical Engineering and Automation Harbin Institute of Technology Harbin People's Republic of China Department of Electronic and Electrical Engineering University of Strathclyde Glasgow UK State Grid Smart Grid Research Institute Beijing People's Republic of China

The modular multilevel converter-based high voltage direct current (MMC-HVdc) overhead lines transmission scheme is the preferred option for wind power integration, though it is susceptible to dc faults. To ensure the connection of a wind farm (WF) to the grid during dc faults, this paper proposes a coordinated control strategy for dc fault ride-through (FRT) based on the energy storage system configured inside the WF for wind power integration through a bipolar MMC-HVdc. In the case of an instantaneous dc fault, the non-fault pole is regulated to operate at full power state to maximise wind power transmission. The exceedance of available wind power outputs over the transmission capacity of the non-fault pole is then accurately allocated to the internal energy storage units (ESUs) of wind generators (WGs) in order to ensure the power balance of the system and reduce the state of charge variance of ESUs as soon as possible. In order to reduce the energy capacities of ESUs required to store the excessive wind power in the event of a permanent dc fault, the method of step-by-step removing WGs is adopted to ensure the system power remaining balanced when the internal ESUs of the disconnected WGs are out of operation. The model is developed and carried out on the PSCAD/EMTdc simulation platform to verify the effectiveness of the proposed control strategies.

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Generalized Study on Analysis and Suppression Strategy of Circulating Current for Modular Multilevel Cascaded Converters

Generalized Study on Analysis and Suppression Strategy of Ci...

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smart Power & Internet Energy Systems (SPIES), International Conference on

作者： Mengchao He Yunfei Xu Zhengang Lu Guoliang Zhao Minxiao Han State Key Laboratory of Alternate Electrical Power System With Renewable Energy Source North China Electric Power University Beijing China State Key Laboratory of Advanced Power Transmission Technology State Grid Smart Grid Research Institute Co. Ltd Beijing China State Key Laboratory of Electrical Equipment and Electrical Insulation Xi'an Jiaotong University Xi'an China

Modular multilevel cascaded converter (MMCC) is widely used in medium and high voltage energy conversion in power systems. Circulating current and branch power fluctuation are common problems in MMCC, and due to different topologies, submodule types and input/output properties, their characteristics vary greatly. In this paper, a general characteristic analysis method of circulating current based on MMCCs’ network topologies is proposed. On this basis, a general suppression strategy for circulating current is proposed, which is easy to implement and can be combined with a branch energy balance strategy. The correctness of the proposed theoretical analysis and control algorithm, which provides an important theoretical basis for the development and application of MMCC is verified by the PSCAD/EMTdc simulation platform.

关键词： Fluctuations Network topology Genetic expression High-voltage techniques Energy conversion Control systems Topology

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Probabilistic Power Flow Calculation of AC/dc Hybrid System Based on Cumulant Method

arXiv

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arXiv 2022年

作者： Sun, Yinfeng Xia, Dapeng Gao, Zichun Wang, Zhenhao Li, Guoqing Lu, Weihua Wu, Xueguang Li, Yang Key Laboratory of Modern Power System Simulation and Control & Renewable Energy Technology Ministry of Education Northeast Electric Power University Jilin132012 China Global Energy Interconnection Research Institute Beijing102211 China Beijing Key Laboratory of DC Power Grid Technologies and Simulation Beijing102211 China

The operating conditions of the power system have become more complex and changeable. This paper proposes a probabilistic power flow calculation method based on the cumulant method for the voltage sourced converter high voltage direct current (VSC-HVdc) hybrid system containing photovoltaic grid-connected systems. Firstly, the corresponding control mode is set for the converter, including droop control and master-slave control. The unified iterative method is used to calculate the conventional AC/dc power flow. Secondly, on the basis of the probability model of load and photovoltaic output, based on the aforementioned power flow results, use correlation coefficient matrix of this paper will change the relevant sample into independent sample，the cumulants of the load and photovoltaic output are obtained;Then, the probability density function (PDF) and cumulative distribution function (CDF) of state variables are obtained by using Gram-Charlie series expansion method. Finally, the mean value and standard deviation of node voltage and line power are calculated on the modified IEEE 34-bus and IEEE 57-bus transmission systems. The algorithm can reflect the inherent uncertainty of new energy sources, and replace the complex convolution operation, greatly improving the calculation speed and the convergence. Copyright © 2022, The Authors. All rights reserved.

关键词： Electric load flow

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Development and prospect of direct‐current circuit breaker in China

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High Voltage 2021年第1期6卷 1-15页

作者： Weijiang Chen Rong Zeng Junjia He Yi Wu Xiaoguang Wei Taixun Fang Zhanqing Yu Zhao Yuan Yifei Wu Wandi Zhou Bing Yang Lu Qu STATE GRID Corporation of China BeijingChina Department of Electrical Engineering Key Laboratory of Control and Simulation of Power System and Generation EquipmentTsinghua UniversityBeijingChina School of Electric and Electronic Engineering Huazhong University of Science&TechnologyWuhanChina School of Electrical Engineering Xi'an Jiaotong UniversityXi'anChina Global Energy Interconnection Research Institute Co. LtdBeijingChina NR Electric Co. LtdNanjingChina

The direct‐current circuit breaker(dcCB)is the most ideal choice for dc fault isolation in dc *** a late start,China's research and development on the dcCB have made outstanding *** article provides a brief glance of current China's dcCB development *** begins by sorting out the technical route according to the topology of *** it systematically summarises both mechanical and hybrid dcCBs with focussing on the aspects of topology structure and principle,key technology and characteristics,prototype development and *** is apparent that Chinese scientists and engineers confronted the worldwide problem of large capacity dc breaking,and put forward a comprehensive solution which consists of an innovative topology structure based on coupled negative voltage circuit,breaking throughs on the key technologies such as highly controllable and reliable fault current commutation,millisecond‐level ultra‐fast and efficient electromagnetic repulsion mechanism,high tolerance and high stability power electronic switch,low residual voltage and fast response energy consumption device,*** article states that the world's first set of hybrid high‐voltage(HV)dcCB,and the first set of mechanical HV dcCB have been *** dcCBs will soon be deployed to the dc grids which have the highest voltage levels therefore require the strongest breaking *** achievements are leading the world in the development and application of *** article also discusses the overall development trends of dcCB in the areas of new topologies,key techno-logical breakthroughs and application scenarios,*** discussions serve as references for dcCB's future technological advancement and its ever‐expanding applications.

关键词： breaking breakthrough discussions

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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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