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Habitat suitability model of the four major Chinese carps

Yingyong Jichu yu Gongcheng Kexue Xuebao/Journal of Basic Science and Engineering 2011年第SUPPL. 1期19卷 123-129页

作者： Yi, Yujun Zhang, Shanghong Ministry of Education Key Laboratory for Water and Sediment Sciences Beijing Normal University Beijing 100875 China State Key Joint Laboratory of Environment Simulation and Pollution Control School of Environment Beijing Normal University Beijing 100875 China Renewable Energy School North China Electric Power University Beijing 102206 China

Coupling habitat suitability function of carps spawning sites with one-dimensional mathematical model, a Habitat Suitability Index (HSI) model to calculate the habitat suitability indices for the four major Chinese carp species was developed. The model was validated by measured data. Using the Habitat Suitability Index model of the four major Chinese carps, the stream habitat for the carp species under different hydraulic condition were assessed. Minimum instream flow and suitable daily discharge increase during the reproduction season for the carp species were suggested. The minimum discharge needed for the four major Chinese carp species in the middle reach of the Yangtze River is 3000 m3/s. Different daily discharge increases are required for different initial discharges. When the initial discharge is 4000 m3/s, the optimal daily discharge increase is approximately 500 m3/(s. d);and when the initial discharge is 9000 m3/s, the optimal daily discharge increase is approximately 800 m3/ (s. d);when initial discharge is 15000 m3/s, the optimal daily discharge increase is approximately 1000 m3/(s. d). Too small or too large of a daily discharge increase is not good for carps spawning.

关键词： Functions

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Non-Rigid Metal–Oxygen Bonding Empowered Nitrate Reduction on Ruthenium Catalysts

SSRN

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SSRN 2024年

作者： Wang, Suwen Zhuang, Zechao Xu, Jiawei Fu, Cheng Qiu, Zhen Feng, Huajun Xiang, Hai Chen, Zuliang Li, Hui Zhang, Lei Li, Yongfu Cai, Yanjiang Ma, Tianyi Yu, Bing State Key Laboratory of Subtropical Silviculture Zhejiang A&F University Hangzhou311300 China Zhejiang A&F University Hangzhou311300 China Department of Chemistry Tsinghua University Beijing100084 China Jiangsu Key Laboratory of Numerical Simulation of Large Scale Complex Systems School of Chemistry and Materials Science Nanjing Normal University Nanjing210023 China Fujian Key Laboratory of Pollution Control and Resource Reuse School of Environmental and Resource Sciences Fujian Normal University Fujian Province Fuzhou350007 China School of Science RMIT University MelbourneVIC3000 Australia Centre for Translational Atomaterials

Electrocatalytic nitrate reduction (NitRR) offers exciting potential for mass production of ammonia (NH3) from renewables. However, the rigidity of metal−ligand bonds in most electrocatalysts renders them unable to survive the structural transformations required for NitRR. Herein, we establish a type of non-rigid metal−oxygen bonds by employing graphene oxide (GO) sheets as a 'micron-scale' ligand for transition metals (TM). Because of being confined to the interfaces between GO and TM, the oxygenated groups in GO can associate with and dissociate from the TM in response to reaction dynamics. As a proof-of-concept demonstration, an electrocatalyst was developed by dispersing nanoscale ruthenium (Ru) on graphene oxide (GO) and utilizing two-dimensional MXene to compensate for the low electrical conductivity of GO. This electrocatalyst exhibits a maximum NH3 yield of over 5 mg cm−2 h−1, with almost 100% current-to-NH3 efficiency, far outperforming the performance of most reported Ru-based materials. What's even more remarkable is the achievement of a record-breaking performance: a 200-hour stable electrolysis with a NH3 yield of 40.2 mg cm−2 h−1, using a membrane electrode reactor. Our experimental and theoretical investigations further reveal the non-rigidity of the Ru–O bonds and how they self-regulate to adapt to diverse intermediates involved in NitRR. This work provides an approach to fabricate a high-performance electrocatalyst featuring reversible and non-rigid metal−oxygen bonds, opening new possibilities for practical nitrate electrolysis. © 2024, The Authors. All rights reserved.

关键词： Electrocatalysis

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Shaping Effect of Phase-locked Loop on Impedance Characteristics of PMSG Wind Turbines Connected to Weak-grid

Shaping Effect of Phase-locked Loop on Impedance Characteris...

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IEEE General Meeting power& Energy Society

作者： Feiya Wan Zhen Li Bin Liu Guanghui Li Xiaoliang Dong Xi Chen Samson S. Yu Amanullah M. T. Oo Zhenyu Shan Xiangdong Liu School of Automation and Key Laboratory for Intelligent Control & Decision on Complex Systems Beijing Institute of Technology Beijing China China Electric Power Research Institute Beijing China State Grid Corporation of China and North China Branch of State Grid Corporation of China Beijing China GEIRI North America USA School of Engineering Deakin University 75 Pigdon Rd Waurn Ponds Victoria Australia School of Electrical and Control Engineering North China University of Technology Beijing China

ISBN: (数字)9781728155081

ISBN: (纸本)9781728155098

With the booming installed capacity of permanent magnet synchronous generator (PMSG) for wind energy generation, the grid becomes weaker and the oscillation events are frequently observed in weak-grid-tied large-scale grid-connected PMSG wind farms. Although the impedance-based method is effective to analyze the stability of grid-connected systems, the mathematical relationship between external impedance characteristics and the internal controllers has not been quantitatively analyzed in depth, which is beneficial to the controller design. This paper studies the influence of phase-locked loop (PLL) on the impedance characteristics based on the analytical sequence impedance model of PMSG with typical topology and control structure. The shaping effect of PLL on the impedance characteristics is described so as to clearly describe the relationship between the external impedance characteristics of the wind turbines and the internal controller. Finally, the stability analysis of the grid-connected PMSG wind turbine system is provided in Matlab and simulation results are given to verify the oscillating mechanism caused by PLL.

关键词： Synchronous generators Stability analysis Wind turbines Topology Impedance Phase locked loops Oscillators

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On Nash-Stackelberg-Nash Games under Decision-Dependent Uncertainties: Model and Equilibrium

arXiv

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arXiv 2022年

作者： Zhang, Yunfan Liu, Feng Wang, Zhaojian Chen, Yue Feng, Shuanglei Wu, Qiuwei Hou, Yunhe State Key Laboratory of Power Systems Department of Electrical Engineering Tsinghua University Beijing China MOE Key Laboratory of System Control and Information Processing Department of Automation Shanghai Jiao Tong University Shanghai China Department of Mechanical and Automation Engineering The Chinese University of Hong Kong Hong Kong Hong Kong Renewable Energy Research Center China Electric Power Research Institute Beijing China Center for Electric Power and Energy Department of Electrical Engineering Technical University of Denmark Kgs. Lyngby Denmark Shenzhen Institute of Research and Innovation The University of Hong Kong Hong Kong

In this paper, we discuss a class of two-stage hierarchical games with multiple leaders and followers, which is called Nash-Stackelberg-Nash (N-S-N) games. Particularly, we consider N-S-N games under decision-dependent uncertainties (DDUs). DDUs refer to the uncertainties that are affected by the strategies of decision-makers and have been rarely addressed in game equilibrium analysis. In this paper, we first formulate the N-S-N games with DDUs of complete ignorance, where the interactions between the players and DDUs are characterized by uncertainty sets that depend parametrically on the players’ strategies. Then, a rigorous definition for the equilibrium of the game is established by consolidating generalized Nash equilibrium and Pareto-Nash equilibrium. Afterward, we prove the existence of the equilibrium of N-S-N games under DDUs by applying Kakutani’s fixed-point theorem. Finally, an illustrative example is provided to show the impact of DDUs on the equilibrium of N-S-N games. Copyright © 2022, The Authors. All rights reserved.

关键词： Game theory

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Analysis and control of Doubly Fed Induction Generator for Zero Voltage Ride Through

Analysis and Control of Doubly Fed Induction Generator for Z...

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International Conference on Electrical Machines and systems

作者： Haiyan Tang Yuanzhu Chang Yongning Chi Bo Wang Yan Li Jiabing Hu State Key Laboratory of Operation and Control of Renewable Energy & Storage Systems China Electric Power Research Institute. Beijing 100192 China State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan 430074 China

ISBN: (纸本)9781467388634

The stator transient DC flux component emerges in the Double Fed Induction Generator (DFIG) following grid voltage dip, which results in an important influence on the controllability of rotor converter. In this paper, the research focuses on the responding time of the dynamic reactive current injection referring to DFIG with the crowbar protection under Zero Voltage Ride-Through (ZVRT). Firstly, theoretical analysis about the shortest quitting time of crowbar is carried out. Then, combined with crowbar protection and demagnetization control, ZVRT of DFIG is achieved as well as the fast injection of dynamic reactive current. Finally, the simulation results are presented to verify the theoretical analysis and the proposed control strategy. It is helpful to enhance fault ride through capability of DFIG.

关键词： Crowbar DFIG Dynamic reactive current injection ZVRT

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Multi-objective optimal dispatch method based on source-network-load-storage interaction system for DC distribution network

Multi-objective optimal dispatch method based on source-netw...

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International Conference on Renewable power Generation

作者： Ran Quan Guoqing Li Guobin Jin Zhao Liu Qing Chen Key Laboratory of Modern Power System Simulation and Control & Renewable Energy Technology Ministry of Education Northeast Electric Power University Jilin China State Grid Jiangsu Electric Power Co. Ltd. Nanjing China Jiangsu Electric Power Company Research Institute Nanjing China

ISBN: (数字)9781839531248

ISBN: (纸本)9781839531255

The DC distribution network can integrate the photovoltaic power generation system with high efficiency, but the random fluctuation of the photovoltaic output power is strong and there is a problem of PV consumption, which has a certain degree of impact on the economic optimization operation of the system. Therefore, the source-network-load-storage optimization interaction concept is introduced in the DC distribution network. Based on the in-depth analysis of the interactive load characteristics, the interaction load and energy storage technology can be fully utilized to the system to consumpt the photovoltaic. Combined with the features of DC distribution network structure, comprehensively consider the impact of the interactive load and energy storage system collaborative optimization on the system operating cost and power flow distribution, so that both the power generation side and the power side can participate in the resource optimization configuration of the grid operation. A multi-objective optimal scheduling model for photovoltaic DC distribution networks with operational cost, network loss and voltage deviation is established. The simulation example shows that: Collaborative optimization using interactive load and energy storage system can greatly reduce system operating cost, network loss and voltage deviation, effectively improve the level of PV consumption, and realize safe and reliable operation of DC distribution network.

关键词： DC distribution network Distributed photovoltaic Energy storage system Interactive load Optimal scheduling

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Evaluating Comprehensive Development Quality of a Regional power Grid by Using an Integrated Multi-criteria Decision-Making Methodology

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IOP Conference Series: Materials Science and Engineering 2019年第4期612卷

作者： Xiaodong Zhang Kaiming Qin Ruihua Si Xianjun Ge State Grid Henan Electric Power Company Zhengzhou 450018 China State Key Laboratory of Power System and Power Generation Equipment Control and Simulation Department of Electrical Engineering Tsinghua University Haidian Beijing 100084 China

Due to the economic situation changes and the continuous expansion of new energy power in China, a new evaluation methodology based on multi-criteria decision making (MCDM) should be proposed to promote the comprehensive development of the new regional power grid. Some criteria were selected to constitute an indicator system from the perspectives of the safety reliability, network structure and economic benefit. Then, an integrated evaluation model was proposed based on fuzzy AHP method and VIKOR method was applied to calculate a series of comprehensive evaluation indexes. A regional power grid was chosen as an empirical analysis to demonstrate the feasibility of the evaluation system.

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Impedance fault location algorithm for UHV long transmission lines with single-line-to-ground faults

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Dianli Xitong Zidonghua/Automation of Electric power systems 2008年第14期32卷 25-29页

作者： Wang, Bin Dong, Xinzhou Bo, Zhiqian Klimek, Andrew State Key Lab. of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing 100084 China AREVA T and D Automation Co. Stafford ST17 4LX United Kingdom

Ultra-high-voltage (UHV) transmission lines (over 750 kV) normally have larger shunt capacitance and longer transmission radius, which impose limitations of direct application of traditional impedance algorithm. A novel impedance fault location algorithm is proposed for UHV transmission lines with single-line-to-ground faults due to higher voltage level than 750 kV. It is based on the precondition that the negative sequence current phase at meter location can precisely describe the phase information of negative current in fault path or fault voltage. The algorithm is immune to the influence of shunt capacitance with distributed parameters modeling for transmission line, and is not disturbed by fault resistance with fault location calculation at zero-crossing point of voltage at fault point. Theoretical analysis and simulation prove that the proposed method can guarantee good fault location accuracy, and fulfill the requirements in the field.

关键词： Electric lines

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Joint Multi-stage Planning of Renewable Generation, HESS, and AESS for Deeply Decarbonizing power systems with High-penetration Renewables

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IEEE Transactions on Sustainable Energy 2024年

作者： Yu, Zhipeng Chi, Yingtian Lin, Jin Liu, Feng Li, Jiarong Song, Yonghua Ren, Zhengwei Lu, Chengcheng Ji, Mengbo Tsinghua University State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Beijing100087 China Tsinghua University Sichuan Energy Internet Research Institute Chengdu610213 China Harvard University Harvard John A. Paulson School of Engineering and Applied Sciences Cambridge United States University of Macau Department of Electrical and Computer Engineering Macau999078 China Tsinghua University Department of Electrical Engineering Beijing100087 China China Electric Power Planning & Engineering Institute National Electric Power Planning and Research Center Beijing100087 China Co. Ltd. Beijing100087 China Ordos City Hanxia Renewable Energy Co. Ltd. Ordos014300 China

The further decarbonization of power systems with high renewable energy penetration faces the problem of inter-day intermittence of renewable energy sources (RES) and the seasonal imbalance between RES and load demand, due to the limited regulation ability of conventional units such as thermal generation. Regular solutions based on battery energy storage system (BESS) are too costly to be practical. To address issues above, hydrogen energy storage system (HESS) and ammonia energy storage system (AESS) are introduced to gradually replace thermal generation. Specifically, first, HESS and AESS are incorporated into the multi-stage capacity expansion planning (MSCEP) model with carbon emission reduction constraints. Yearly data with hourly time resolution are utilized for each stage to accurately describe the intermittence of RES. Then, an improved column generation (CG) with Dantzig-Wolfe decomposition (DWD) embedded solution approach is used to efficiently solve the large-scale MSCEP model. Finally, a real-life system in China is studied. The results indicate that the proposed method can guarantee high power supply reliability (PSR) under different renewable energy penetration levels, avoiding the low PSR problem that may be caused by the existing typical scenario-based method (TSM) under high penetration (≥30%). Moreover, HESS and AESS are essential to reduce the cost of decarbonization. Especially under the goal of carbon neutrality, the contribution of HESS and AESS in reducing levelized cost of energy (LCOE) reaches 12.28% and 14.59%, respectively, leading to a levelized cost of carbon reduction (LCOCr) of 998 RMB/t. © 2010-2012 IEEE.

关键词： Hydrogen storage

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Crack Growth Prediction of the Steam Turbine Generator Shaft

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Journal of Physics: Conference Series 2011年第1期305卷

作者： Dongxiang Jiang Chao Liu State Key Laboratory of Control and Simulation of Power System and Generation Equipments Department of Thermal Engineering Tsinghua University Beijing 100084 People's Republic of China

The power network in China is encountering great changes and large-scale network is increasingly implemented for long distance power transmission as well as various kinds of power electronic devices, which bring in the risk of the torsional vibration of the turbine generator shafts, may cause the fatigue damage and cracks in the product life cycle. The paper analyzed the failed coupling of some 600MW steam turbine generator and calculated the local stress of the assembly under torsional load caused by the network disturbance. Then the crack propagation was analyzed with the predicted crack initiation position and crack propagation routine. The assembled coupling contains shaft, coupling and keys with interferences between the parts. Therefore the contact analysis was included. Extended Finite Element Method (X-FEM) is used to calculate the crack propagation and that the mesh needs not to be regenerated with the crack propagation, which is beneficial for engineering applications.

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