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Wind farm aggregation method based on motion equation concept: a case study

The Journal of engineering 2018年第13期2017卷 708-713页

作者： Zhichao Cui Xiaoming Yuan Meiqing Zhang State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan 430074 People's Republic of China

With large number of wind farms integrating into grid, the dynamic behaviour of power system has been impacted significantly. To study the impacts of wind farm on power system, the dynamic modelling of wind farm is important. Compared with modelling all the wind turbines of wind farm in detail, aggregating the wind farm to reduce the complexity of model is a better choice. Several studies have put forward some aggregation methods, such as single-machine representation and multi-machine representation. However, applicability of these methods is limited and they cannot aggregate different types of wind turbines. This study proposes a wind farm aggregation method based on motion equation concept. By defining bus voltage as internal voltage of the aggregation model, the relationship between internal voltage and unbalanced power of wind farm is established. An aggregated model of wind farm in DC-link voltage control timescale is built and time-domain simulation results are presented to verify the feasibility of this model. The aggregation method can aggregate wind turbines regardless of their types and working status. In addition, this aggregation method can be applied to modelling other systems in other timescales based on motion equation concept.

关键词： wind power plants wind turbines voltage control time-domain analysis time-domain simulation DC-link voltage control timescale unbalanced power internal voltage multimachine representation single-machine representation wind turbines dynamic modelling power system dynamic behaviour motion equation concept wind farm aggregation method

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Analytical model of plasma response to external magnetic perturbation in absence of no-slip condition

arXiv

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arXiv 2019年

作者： Huang, Wenlong Zhu, Ping School of Computer Science and Technology Anhui University of Technology Ma’anshanAnhui243002 China International Joint Research Laboratory of Magnetic Confinement Fusion and Plasma Physics State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology WuhanHubei430074 China Department of Engineering Physics University of Wisconsin-Madison MadisonWI53706 United States

Recent simulation and experimental results suggest that the magnetic island and flow on resonant surface often do not satisfy the "no-slip" condition in the steady state. A new theory model on nonlinear plasma response to external magnetic perturbation in absence of no-slip condition is proposed. The model is composed of the equations for the evolution of both width and phase of magnetic island due to forced reconnection driven by the external magnetic perturbation, and the force-balance equation for the plasma flow. When the island width is much less than the resistive layer width, the island growth is governed by the linear Hahm-Kulsrud-Taylor solution in presence of time-dependent plasma flow. In the other regime when the island width is much larger than the resistive layer width, the evolution of both island width and phase can be described using the Rutherford theory. The island solution is used to construct the quasi-linear electromagnetic force, which together with viscous one, contributes to the nonlinear variation in plasma flow. The no-slip condition assumed in the conventional error field theory is not imposed here, where the island oscillation frequency depends on but does not necessarily equal to the plasma flow frequency at the rational surface. Copyright © 2019, The Authors. All rights reserved.

关键词： Plasma flow

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Multiband filter: estimator of different frequency components of grid voltage

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The Journal of engineering 2018年第13期2017卷 696-701页

作者： Chenhui Huang Xiaoming Yuan Sheng Li State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan 430074 People's Republic of China

With the rapid development of renewable energy, an increasing number of power electronic devices is integrated into the power system. Multi-time-scale controllers of these devices bring about diverse oscillations and harmonics which have threatened the stable operation of the power system. The accurate estimation of oscillations becomes the primary task to tackle this problem. This study proposes a novel cross-coupled filter to accurately detect fundamental component and other frequency components. In addition, the transfer function in the frequency domain is given to describe the actual input–output relationship. Furthermore, the harmonic components which are filtered out do not have amplitude changes and phase shifts between the input and the output. Finally, the accuracy of the transfer function is verified by simulation.

关键词： power filters transfer functions frequency-domain analysis power system stability multiband filter frequency component estimator grid voltage renewable energy power electronic devices multitime-scale controllers diverse oscillations power system operation stability cross-coupled filter fundamental component transfer function frequency domain phase shifts

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Solving the Grad-Shafranov equation using spectral elements for tokamak equilibrium with toroidal rotation

arXiv

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arXiv 2019年

作者： Li, Haolong Zhu, Ping CAS Key Laboratory of Geospace Environment Department of Engineering and Applied Physics University of Science and Technology of China Hefei Anhui230026 China International Joint Research Laboratory of Magnetic Confinement Fusion and Plasma Physics State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology WuhanHubei430074 China Department of Engineering Physics University of Wisconsin-Madison MadisonWI53706 United States

The Grad-Shafranov equation is solved using spectral elements for tokamak equilibrium with toroidal rotation. The Grad-Shafranov solver builds upon and extends the NIMEQ code [Howell and Sovinec, Comput. Phys. Commun. 185 (2014) 1415] previously developed for static tokamak equilibria. Both geometric and algebraic convergence are achieved as the polynomial degree of the spectral-element basis increases. A new analytical solution to the Grad-Shafranov equation is obtained for Solov’ev equilibrium in presence of rigid toroidal rotation, in addition to a previously obtained analytical solution for a defferent set of equilibrium and rotation profiles. The numerical solutions from the extended NIMEQ are benchmarked with the analytical solutions, with good agreements. Besides, the extended NIMEQ code is benchmarked with the FLOW code [L. Guazzotto, R. Betti, et al., Phys. Plasma 11(2004)604]. Copyright © 2019, The Authors. All rights reserved.

关键词： Magnetoplasma

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A method for mitigating subsynchronous oscillation risk based on a novel control strategy of VSC

A method for mitigating subsynchronous oscillation risk base...

引用

8th Renewable Power Generation Conference (RPG 2019)

作者： Wei He Ao Li Xiaoming Yuan Jianqin Liu State Key Laboratory of Advanced Electromagnetic Engineering and Technology and School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan China State Grid Sichuan Economic Research Institute Chengdu China State Grid Economic and Technological Research Institute Co. Ltd Beijing 102209 China

ISBN: (数字)9781839531248

ISBN: (纸本)9781839531255

The penetration of the grid-connected voltage source converter (GCVSC) based renewable power generation in power system is increasing, and the sub-synchronous oscillation (SSO) caused by it is also increasing. This new oscillation phenomenon caused by the power electronic equipment is seriously threatening the safe and stable operation of power system. Due to the huge numbers of power electronic equipment, in order to suppress this kind of oscillation, changing the control strategy of the STATCOM which is stalled in renewable power generation plants is an effective method to restrain the SSO. This paper firstly describes the fundamental reason of the SSO is that the terminal voltage of the GCVSC is greatly affected by the converter voltage. Based on it, a damping control strategy based on STATCOM is proposed to weaken the influence of the converter voltage on the terminal voltage. This method has simple control structure and is not limited to specific oscillation frequency. Finally, the effectiveness of this method is verified by time domain simulation.

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An Experimental Study on Contact Dynamic Welding under Different Contact Materials and Surrounding Atmospheres in HVDC

An Experimental Study on Contact Dynamic Welding under Diffe...

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International Conference on Electric Power Equipment - Switching technology (ICEPE-ST)

作者： Wenxuan Liu Yuan Liao Lin Jiao Xiaoping Bai Ruxin Feng Zhenbiao Li Makoto Hasegawa State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China Fuda Alloy Material Limited by Share Ltd Wenzhou China Zhongxi Group Co. Ltd. Wenzhou China Chitose Institute of Science and Technology Chitose Hokkaido Japan

Contact dynamic welding is a common failure fault of high voltage dc (HVDC) relays. Contact materials and surrounding atmosphere have important influences on the dynamic welding of sealed relay contacts. In this paper, the anti-welding abilities of CuW50, CuW60, AgW60 and Cu contacts are researched in six kinds of ambient atmospheres such as N 2 and CO 2 under the conditions of 200 - 500Vdc and 40 - 150A. The results show that: O 2 has normally the strongest anti-welding ability among all tested atmospheres. The welding force in the gas mixture of 80%CO 2 with 20%Ar is usually smaller than that in 50%CO 2 with 50%Ar. Mixed gases show an "optimal effect" and an "intermediate effect". AgW60 possesses fewest numbers of welding among all of the tested materials, and Cu, the second-fewest. In terms of welding force, mostly it turns out that AgW60 is smaller than Cu and CuW50 is smaller than CuW60.

关键词： Welding Force Contacts Atmosphere Relays Gases Force measurement

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RESEARCH ON OPTIMIZATION CONFIGURATION OF M-SMES IN MICRO-GRID WITH RENEWABLE ENERGY

RESEARCH ON OPTIMIZATION CONFIGURATION OF M-SMES IN MICRO-GR...

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International Conference on Renewable Power Generation

作者： Minghan Gao Yuanyuan Li Jing Shi State Key Laboratory of Advanced Electromagnetic Engineering and Technology (Huazhong University of Science and Technology) Wuhan 430074 Hubei Province China

ISBN: (数字)9781839531248

ISBN: (纸本)9781839531255

Superconducting magnetic energy storage system (SMES) has a broad application prospect in micro-grid due to its fast response ability and high energy storage density. Because of the limitation of superconducting material development level, the capacity of a single SMES can hardly meet the energy storage demand at present, so the energy storage of the power system needs a distributed layout. Modular superconducting magnetic energy storage system (M-SMES) can effectively improve the utilization and economy of SMES by rationally configuring its capacity and planning its layout. For the typical micro-grid with renewable power generation, an optimization method for configuring capacity and planning location of M-SMES is proposed and verified by a case. Firstly, a multi-objective mathematical optimization model is established. Then the capacity and steady-state layout of M-SMES are optimized by Genetic Algorithm (GA), and the function of SMES is verified in transient analysis. Finally, a micro-grid with renewable power generation -- three-generator and nine-bus system is taken as a case to illustrate the effectiveness of the proposed M-SMES capacity and layout optimization scheme.

关键词： M-SMES OPTIMIZATION CONFIGURATION MICRO-GRID

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Event-triggered robust load frequency control of a multi-area power system including wind farms

Event-triggered robust load frequency control of a multi-are...

引用

Chinese Control Conference

作者： Chao Yang Wei Yao Jinyu Wen State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China

Owing to the highly randomness and intermittent nature of wind power generation, the smart grid raises a challenge to maintain real power balances and frequency control in a multi-area power system including wind farms. This paper analyzes the stability of the load frequency control scheme of a multi-area power system including wind farms. To reduce the communication burdens in open communication infrastructure and impact of the extra disturbance, an event-triggered robust load frequency control scheme is proposed for the multi-area power system. Through theoretical proof and simulation test, the effectiveness of the proposed method has been validated in load frequency control of multi-area power systems.

关键词： Power system stability Frequency control Robustness Wind power generation Wind farms Stability analysis

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Analysis and Design of a Modular 100 kW Stand Alone Power System

Analysis and Design of a Modular 100 kW Stand Alone Power Sy...

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China International Electrical and Energy Conference (CIEEC)

作者： Wahab Ali Shah Ali Shan Hengxin He Habib ur Rahman habib Junjia He State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China

ISBN: (纸本)9781538653937

The growing number of energy consuming devices, together with the increasing demand for energy, has led to an energy crisis in the world today. As electricity is an important factor for the development in the economic growth. At this time, the growing population will bring disaster situations relating to electrical energy and pollution; it will affect both the economy and the citizens and make a barrier in the path to complete with developed countries. In order to overcome the epileptic situation of electrical energy and make our environment clean and green. First, we need to give opportunities for renewable energy to address electricity generation. Second, there is no other way to reduce complexity and eliminate energy problem without using solar energy. The solar energy which is renewable energy, environmental friendly and free of cost but still we face difficulty by complete harnessing of solar energy because of variation of irradiation and temperature to get constant point at the output we will use PI controller. Moreover, there is different classification of inverter we used "PWM inverter" that can take steady DC voltage PWM inverter can take in a steady dc voltage. So as to feed solar voltage to the boost converter to step-up solar voltage we used PI controller to control boost converter and get constant voltage at the output the we feed this boost DC voltage to the 3phase PWM inverter to converter into three phase AC voltage. Finally, the inverter should direct the extent and the recurrence of AC output voltages, and the diode rectifiers are required to settle the line-to-line voltage.

关键词： Inverters Voltage control Pulse width modulation Inductors Solar energy PI control Voltage measurement

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2D Plasmonic Terahertz Detection under Static Magnetic Field

2D Plasmonic Terahertz Detection under Static Magnetic Field

引用

International Conference on Infrared, Millinmeter, and Terahertz Waves

作者： L. Cao J. Ding Q. Fu B. Wu State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China

The absorption properties of two dimensional plasmonic room temperature terahertz detectors based on semiconductor heterostructures under external magnetic field up to 10 tesla are compared for the AlGaAs/GaAs, SiGe/Si/SiGe and GaN-based materials. The magnetic field provides a way for frequency tunability in the detection process. By sweeping the magnetic field, grating period and aspect ratio, and the barrier thickness, the absorption spectrum is optimized in the frequency range 1 ~ 5 THz.

关键词： Resonant frequency Magnetic fields Absorption Gratings Cyclotrons Aluminum gallium nitride Wide band gap semiconductors

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