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Semi-empirical equivalent circuit model and evaluation of energy losses for alkaline electrolysis stack in dynamic operations

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International Journal of Hydrogen Energy 2025年 138卷 859-873页

作者： Sha, LianDong Lin, Jin Qi, Ruomei Li, Qinghui Li, Wenying Lin, Ruixiao Gao, Danhui Li, Hang Li, Xiaolong Yang, Chenxi Song, Yonghua State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing 100084 China Tsinghua-Sichuan Energy Internet Research Institute Chengdu 610213 China School of Chemistry and Chemical Engineering Southwest Petroleum University Chengdu 610213 China School of Nuclear Science and Engineering North China Electric Power University Beijing 100084 China State Key Laboratory of Internet of Things for Smart City University of Macau 999078 Macao

In various applications of alkaline water electrolysis (AWE) for hydrogen production, the efficiency of AWE stacks is a critical concern. Emerging applications involve significant dynamic operations, necessitating the evaluation of their impact on stack efficiency. However, a quantitative understanding of the power losses within AWE stacks under dynamic conditions remains limited. A significant research challenge exists in the development of models for AWE stacks that can accommodate dynamic operating conditions, and there is a need for a systematic approach to classify and quantify energy losses within the stack. This paper presents a quantitative assessment method for losses in AWE stacks based on a semi-empirical equivalent circuit model (SECM). The losses within the AWE stack are categorized into four types based on their generation mechanisms: overpotential losses, shunt current losses, non-Faradaic losses, and electrochemical cycling losses (cycling losses for short). Using experimental data from 5 MW and 10 kW AWE stacks, the parameters of the SECM observer are identified through a stepwise data-driven approach, resulting in a mean square error of less than 46.4 mV for 5 MW stack and 80.9 mV for 10 kW stack. The constructed SECM observer is employed to simulate the proportion of various losses under different dynamic operating conditions. This paper focuses on the efficiency and loss behaviors of AWE stacks under multi-stack switching strategies. Case studies demonstrate that the current range, ramp rate, regulation period, and duty cycle significantly influence the four types of losses. Based on the SECM observer, recommended parameters for multi-stack switching are provided. This work contributes to accurate assessment of AWE stack efficiency under dynamic operations and provides a methodology for designing AWE stack operating strategies. © 2025 Hydrogen Energy Publications LLC

关键词： Alkaline water electrolysis stack Dynamic operation Efficiency Electrochemical cycling losses Equivalent circuit model Multi-stack switching strategies

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Performance-Aware control of Modular Batteries For Fast Frequency Response

arXiv

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arXiv 2025年

作者： He, Yutong Ruan, Guangchun Zhong, Haiwang State Key Laboratory of Power System Operation and Control Department of Electrical Engineering Tsinghua University Beijing100084 China Lab for Information and Decision Systems Massachusetts Institute of Technology CambridgeMA02139 United States

Modular batteries can be aggregated to deliver frequency regulation services for power grids. Although utilizing the idle capacity of battery modules is financially attractive, it remains challenging to consider the heterogeneous module-level characteristics such as dynamic operational efficiencies and battery degradation. In addition, real-time decision making within seconds is required to enable fast frequency response. In order to address these issues, this paper proposes a performance-aware scheduling approach for battery modules to deliver fast frequency response (FFR) support. In particular, the conduction loss and switching loss of battery packs as well as converters are captured within a mix-integer quadratic constrained program (MIQCP). The cycle-based aging model identifies the aging cost of battery modules during frequent cycling by introducing the aging subgradient calculation and linearization. Case studies based on real-world battery data show that the proposed scheduling approach can effectively reduce power loss cost by nearly 28%-57% and battery aging cost by 4%-15% compared to conventional methods, which can also enhance the SoC balance. Copyright © 2025, The Authors. All rights reserved.

关键词： Battery management systems

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Linear Precoding Design for MIMO-PLC systems

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Tsinghua Science and Technology 2015年第2期20卷 155-163页

作者： Jisheng Peng the State Key Lab of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua Uinversity

In this paper, we consider the design of linear precoding in Multiple Input Multiple Output （MIMO） power Line Communication （PLC） systems with finite-alphabet input. First, we derive mutual information of MIMO-PLC systems with impulsive noise. Considering the non-concavity of the objective function and the low-cost requirement of PLC systems, we choose the lower bound of the mutual information as the objective function. Subsequently, we propose a novel approach to design the precoding scheme to reduce computational complexity. Specifically, our work primarily includes the following two contributions：（1） We design the right unitary matrix that is a product of two fixed unitary matrices, which only depends on the modulation mode. Hence, the results can be saved and require less computations. （2） For the power allocation matrix, we first reduce the space of power allocation using constraints of the optimal power allocation policy. Consequently, we propose a non-linear search method to obtain the optimal power allocation in small space. In regards to the computational complexity of the analysis, we conclude that the proposed precoding matrix design scheme has low complexity and is easy to implement. Moreover, the numerical results are proven to demonstrate the performance of the proposed precoding design scheme.

关键词： precoding design MIMO-PLC impulsive noise finite-alphabet input

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Recent advances on smart grid technology and renewable energy integration

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Science China(Technological Sciences) 2013年第12期56卷 3040-3048页

作者： MEI ShengWei CHEN LaiJun State Key Lab of Control and Simulation of Power Systems and Generation Equipments (Dept. of Electrical Engineering Tsinghua University)

With the integration of renewable energy generations and other related changes,the smart grid,or the future electric power system,is confronted with new challenges and ***,it is a promising subject in electrical engineering and much work has been done on *** paper reviews the recent advances on the technologies of smart grid and renewable energy integration,from the aspects of modeling,simulation,protection and control,stability,operation,and planning.

关键词： smart grid renewable energy integration modeling simulation protection and control stability operation planning

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Estimation of the electromechanical characteristics of power systems based on a revised stochastic subspace method and the stabilization diagram

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Science China(Technological Sciences) 2012年第6期55卷 1677-1687页

作者： NI JingMin SHEN Chen LIU Feng State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Beijing 100084China

Estimating low-frequency oscillation modes and the corresponding mode shapes based on ambient data from WAMS measurements has a promising prospect in power system analysis and *** on the stochastic subspace method,this paper proposes a revised stochastic subspace method by introducing reference channels,which can estimate the modes and the mode shapes simultaneously with great computational ***,the accuracy of the estimated results is not *** discriminate the real modes from the spurious ones,the stabilization diagram is introduced.A novel algorithm is designed to deal with the stabilization diagram which can detect the real modes *** conducted on the IEEE-118 system indicate that the proposed method has good performance in terms of both computational efficiency and accuracy,and has the potential of being used on-line.

关键词： electromechanical oscillation ambient data stochastic subspace method reference channels stabilization diagram

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Short-term wind power forecast with turning weather based on DBSCAN-RFE-LightGBM

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Renewable Energy 2025年 251卷

作者： Wu, Zhenlong Fan, Xinyu Bian, Guibin Liu, Yanhong Zhang, Xiaoke Chen, YangQuan School of Electrical and Information Engineering Zhengzhou University Zhengzhou450001 China State Key Laboratory of Intelligent Agricultural Power Equipment Zhengzhou University Luoyang471000 China State Key Laboratory of Management and Control for Complex Systems Institute of Automation Chinese Academy of Sciences Beijing100190 China Electric Power Research Institute of State Grid Henan Electric Power Company Zhengzhou450052 China Lab Department of Mechanical Engineering School of Engineering University of California MercedCA95343 United States

At present, the wind power prediction technology is becoming more and more mature, however, the turning weather brings a decrease in prediction accuracy due to its suddenness and instability. In this paper, a wind power prediction method considering the turning period and non-turning period respectively is proposed to weaken the adverse effects caused by turning weather. Firstly, the prediction effects of multiple models are compared, density-based spatial clustering of applications with noise (DBSCAN) is selected as the outlier processing method, recursive feature elimination (RFE) is used as the feature selection method, and Light gradient boosting machine (LightGBM) is used for prediction. The combined prediction method based on DBSCAN-RFE-LightGBM can reduce the influence of abnormal data and redundant features and improve the prediction effect. Then, the sliding window is set to detect the turning period. Considering that the turning weather is an emergency and does not happen frequently, the amount of data is small, which leads to the inability to train the model well. Generative adversarial networks (GAN) are applied to expand the turning period data. The LightGBM is trained and predicted by using the expended turning period data. Finally, the time-division prediction results are merged. Using the data collected from wind farms for short-term power prediction experiments, the time-segment prediction method proposed in this paper with GAN reduces MAE by 1.913 and RMSE by 3.351 on a single unit compared with the non-differentiated period. © 2025 Elsevier Ltd

关键词： Merging

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Fault diagnosis method for blade fracture of gas turbine based on casing vibration

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Mechanical systems and Signal Processing 2025年 234卷

作者： Hu, Ming-Hui Jin, Bao-teng Liu, Shao-Peng Wang, Wei-Min Jiang, Zhi-Nong Zhang, Xiao-Yang Gao, Jin-ji State Key Laboratory of High-end Compressor and System Technology Beijing University of Chemical Technology Beijing100029 China Key Lab of Engine Health Monitoring-Control and Networking of Ministry of Education Beijing University of Chemical Technology Beijing100029 China Beijing Key Laboratory of Health Monitoring and Self-Recovery for High-End Mechanical Equipment Beijing University of Chemical Technology Beijing100029 China National Key Laboratory of Internal Combustion Engines and Power Systems Weichai Power Co. Ltd. China

Blade fracture is one of the most difficult faults to diagnose in rotating machinery. Most gas turbines can only measure casing vibration rather than directly measuring blade vibration with other sensors, making monitoring and diagnosing such faults more challenging. Research on vibration characteristics and fault diagnosis methods of blade fracture is critical to ensure the safe and reliable operation of gas turbines. The current paper presents a new method to monitor the blade fracture faults from the vibration signal of the casing. Firstly, based on the function mechanism of blade wake excitation forces, the transfer path of the vibration response of gas turbine blades and the variation rule of the wake excitation force have been investigated. Then, based on the casing vibration response model, we analyzed the dynamic evolution of vibration response in the pre- and post-fracture stages of rotor blade failure. The results indicate that the response characteristics of velocity RMS, blade passing frequency (BPF), and fundamental frequency can effectively characterize blade fracture faults. Secondly, based on the vibration-sensitive characteristics of blade fracture faults, we propose an Improved Ordered Cluster Analysis (IOCA) identification method. Considering that the blade fracture can decrease the BPF amplitude and lead to the appearance of side-frequency bands. We propose a Fault Localization Estimation (FLE) method, which constructs a fracture localization factor called ΔUBF, and the highest ΔUBF value corresponds to the stage where the blade fracture has appeared. Finally, A fault diagnosis scheme for gas turbine blade fracture based on casing vibration is proposed. An engineering case of a gas turbine blade fracture fault is analyzed. The results show that the proposed method can timely and effectively diagnose the gas turbine blade fracture fault from the vibration signal of the casing. They can further localize the blade fracture fault at the 8th and 9th s

关键词： Rotating machinery

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Simplified mathematical model of inter-turn short circuit of field windings in hydro-generators and its application

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Science China(Technological Sciences) 2013年第4期56卷 898-909页

作者： HAO LiangLiang WU JunYong SUN YuGuang WANG XiangHeng School of Electrical Engineering Beijing Jiaotong University State Key Lab of Control and Simulation of Power Systems and Generation Equipment Tsinghua University

Inter-turn short circuit of field windings is a common electrical fault of *** is an important method of investigating the fault and providing data support for fault ***,huge numbers of pole pairs and damper loops in large hydro-generators would lead to lengthy calculation time,hindering scientific research and engineering *** deal with this problem,we analyze a theoretical basis for a damper winding simplified model and then propose an equivalent treatment *** the analysis of steady-state current harmonic characteristics of generators with different stator winding configurations during the fault,the simplified models suitable for steady-state calculation are derived from two aspects,namely,additional rotor harmonic current frequency characteristics and the relationship of the amplitude as well as the phase of each branch current of the *** calculation and experimental results of the two simplified models are then compared to verify the models' correctness.A calculation example of the Three Gorges left bank VGS generator shows few deviations between the calculation results of the simplified model and the original ***,the calculation time using the simplified model is 1/1500 that using the original model,which provides a more effective tool for on-line fault ***,the sensitivity-verification application of the fault-monitoring scheme based on the stator steady-state unbalanced current RMS is *** result shows that the scheme can monitor two-turn short circuits of field windings in the Three Gorges generator and provide high sensitivity.

关键词： hydro-generator field windings inter-turn short circuit simplified model on-line monitoring

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Dynamic simulation based on Jacobian-free Newton-GMRES methods with adaptive preconditioner for power systems

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Science China(Technological Sciences) 2013年第8期56卷 2037-2045页

作者： HUANG ShaoWei CHEN Ying SHEN Chen MEI ShengWei State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments(Department of Electrical Engineering Tsinghua University)

Dynamic simulation is one of the most complex and important computations for power systems *** solutions based on normal Newton iterations almost all depend on evaluations of Jacobian matrixes,which increases the programming complexity of and limits the parallelizability of the whole *** this paper,a new adaptive preconditioned Jacobian-free Newton-GMRES(m)method is proposed to be applied to dynamic simulations of power *** new method has totally Jacobian-free characteristics,which saves calculations and storages of Jacobian matrixes and features strong ***,several speedup strategies are introduced to enhance efficiency and parallelizability of overall *** tests are carried out on IEEE standard test systems and results show that in series computing environment,simulations based on the proposed method have comparable speed to those based on classical Newton-Raphson methods.

关键词： dynamic simulation Newton-GMRES preconditioner power system

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A game-theoretic method for prediction of microgrid growing trends in China

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Science China(Technological Sciences) 2015年第10期58卷 1760-1766页

作者： ZHAO Min SHEN Chen LIU Feng HUANG XiuQiong State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Department of Electrical EngineeringTsinghua University Guangxi Power Grid Corporation China Southern Grid

This paper presents a game-theoretic method to predict microgrid(MG) development tendency in China. As many distribution generators(DGs) are integrated in distribution systems, analysis of MG formation necessity is conducted from the aspect of DGs. In order to maximize the profit brought by DGs and to earn money from arbitrage, it may be necessary for customers to combine their DGs and loads and to construct an MG to obtain maximal control ability. A game model is built to emulate trading between MGs and the distribution system based on MG power control, in which both trading profit and outage cost are considered for each MG. Nash equilibrium(NE) is calculated, and sensitivities of NE to some boundary conditions are studied. The results show that variable MG trading prices with appropriate net generation cost(i.e., DG generation cost minus government subsidy price) may encourage the growth of MGs. Government subsidies, generation costs, and trading prices may also affect DG use, and therefore they may impact customer motivation to build MGs.

关键词： microgrid game distributed generation smart grid

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