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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 Beijing100084 China Tsinghua-Sichuan Energy Internet Research Institute Chengdu610213 China School of Chemistry and Chemical Engineering Southwest Petroleum University Chengdu610213 China School of Nuclear Science and Engineering North China Electric Power University Beijing100084 China State Key Laboratory of Internet of Things for Smart City University of Macau 999078 China

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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Alkaline molten salt thermal treatment of mixed waste plastics for oil production: Insight into the effects of molten salt alkalinity and plastic molecular structure

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Fuel 2025年 399卷

作者： Ren, Yang Dai, Qiqi He, Jing Hu, Hongyun Li, Xian Li, Aijun Zhang, Changbin Yao, Hong State Key Laboratory of Coal Combustion School of Energy and Power Engineering Huazhong University of Science and Technology Wuhan430074 China Research Institute of Huazhong University of Science and Technology in Shenzhen Shenzhen518000 China State Key Joint Laboratory of Environment Simulation and Pollution Control Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing100085 China

Pyrolysis has emerged as the primary strategy for recycling waste plastics into oil. However, the low thermal conductivity of plastics results in inefficient heat transfer and extended residence times, which is unfavorable for oil production. Here, a novel method by using thermally stable alkaline molten salt as an effective medium to enhance heat transfer and thermal reaction was proposed. The oil yield exhibited a direct correlation with molten salt alkalinity. NaOH-Na2CO3 system achieved remarkable gas upgrading: >99 % chlorine immobilization coupled with alkali-mediated hydrogen enrichment (H2 ratio > 80 %), enabled by catalytic carbon-alkali interactions. Plastic molecular structures governed product selectivity during molten salt thermal treatment: polyolefins (PE/PP) predominantly yielded α-olefins through promoting β-scission reactions, while polyvinyl chloride (PVC) and polystyrene decomposition generated aromatic hydrocarbons (BTX, styrene) via enhancing dehydrochlorination and aromatization. In co-processing of mixed plastics, weak interactions existed between PE and PP during both conventional and molten salt conversions, with product distributions resembling linear combinations of individual pyrolysis results. PVC-PS blends exhibited significant cross-reactivity: HCl evolved from PVC decomposition engaged in secondary reactions with styrene (PS product). Primary radicals on PS chains post-scission drove depolymerization pathways, elevating ethylbenzene/α-methylstyrene formation at the expense of styrene monomers. Molten salt reduced PVC-PS cross-reactivity via chlorine capture and H-radical redistribution, increasing styrene monomer yields by 142 %. These findings facilitate the high-value recycling of mixed waste plastics for oil production. © 2025 Elsevier Ltd

关键词： Isomers

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Categorical Spatial Interpolation of Solar Irradiance for Regional Distributed Photovoltaic power Forecasting

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IEEE Transactions on Sustainable Energy 2025年

作者： Ruan, Chenglong Li, Kangping Li, Zhenghui Huang, Chunyi Wang, Fei Shanghai Jiao Tong University College of Smart Energy Shanghai200240 China Shanghai Jiao Tong University Shanghai Non-Carbon Energy Conversion and Utilization Institute Shanghai200240 China Ministry of Education Shanghai Jiao Tong University Key Laboratory of Control of Power Transmission and Conversion Shanghai200240 China North China Electric Power University Department of Electrical Engineering Baoding071003 China State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University Beijing102206 China Hebei Key Laboratory of Distributed Energy Storage and Microgrid North China Electric Power University Baoding071003 China

High-spatial-resolution (HSR) solar irradiance forecast data is important for regional distributed photovoltaic (PV) power forecasting. Distributed PV sites are widely geographically distributed and the cost of obtaining HSR irradiance forecast data with full regional coverage is very high. Improving spatial resolution through interpolation based on limited sparse irradiance forecast reference points is a low-cost and feasible approach. However, existing irradiance spatial interpolation methods would produce large errors under variable weather conditions (e.g., cloudy) with limited reference points, because local abrupt changes in irradiance usually occur under such weather conditions due to cloud movement. This paper proposes a categorical spatial interpolation method to improve the accuracy of distributed PV power forecasting with limited sparse irradiance forecast data. The method first converts satellite-derived shortwave radiation images into binary irradiance maps through adaptive thresholding, then trains a 3D U-net model to predict future irradiance category probabilities for each grid. These probability maps dynamically govern two parallel interpolation processes: one using reference stations in predicted clear-sky regions, another utilizing stations in cloudy zones, with final irradiance values determined by probability-weighted fusion. Case studies on a real dataset verify the effectiveness and superiority of the proposed method. © 2025 IEEE.

关键词： Solar irradiance

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Performance-Aware control of Modular Batteries For Fast Frequency Response

arXiv

引用

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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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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Selection for Schottky Barrier Diodes with Various On-Resistance in Full-SiC Voltage Source Converters

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IEEE Transactions on Industry Applications 2025年

作者： Chen, Yuzhi Li, Chi Liu, Jianwei Wu, Yifan Liu, Zicheng Zheng, Zedong Tsinghua University State Key Laboratory of Power System Operation and Control Department of Electrical Engineering Beijing100084 China Huazhong University of Science and Technology State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Wuhan430074 China

In Silicon Carbide based voltage source converters (VSCs), pairing Schottky barrier diodes (SBDs) presents trade-offs. While SBDs reduce the freewheeling loss and mitigate the adverse effects of bipolar conduction, their junction capacitance also contributes to increased switching loss. This paper proposes a systematic selection strategy for SBDs aimed at enhancing converter efficiency, using on-resistance as the design variable. A three-phase VSC with 1.2 kV MOSFETs and four sets of 1.2 kV SBDs is demonstrated as the case study. The static and switching characteristics for MOSFET/SBD pair are measured and analyzed over a wide temperature range. VSC efficiency is evaluated in both inverter and rectifier modes under different operating conditions. It appears that VSC using SBDs with 126% of the MOSFETs' resistance exhibits an overall superior performance. A 4 kW full-SiC VSC prototype is developed to validate the proposed selection strategy. Compared to other SBDs, using the recommended selection enhances VSC efficiency by up to 2% (± 0.5%) under light loads while maintaining high performance under medium and heavy loads. Compared to freewheeling by the body diode, using the recommended selection enhances VSC efficiency by an average of 0.4% (± 0.1%) across nearly the entire load range. © 1972-2012 IEEE.

关键词： Schottky barrier diodes

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Wavelet-based data compression for wide-area measurement data of oscillations

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Journal of Modern power systems and Clean Energy 2018年第6期6卷 1128-1140页

作者： Lin CHENG Xinchi JI Fang ZHANG He HUANG Song GAO State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University State Grid Jiangsu Electric Power Company

This paper proposes a wavelet-based data compression method to compress the recorded data of oscillations in power systems for wide-area measurement systems. Actual recorded oscillations and simulated oscillations are compressed and reconstructed by the waveletbased data compression method to select the best wavelet functions and decomposition scales according to the criterion of the minimum compression distortion composite index, for a balanced consideration of compression performance and reconstruction accuracy. Based on the selections, the relationship between the oscillation frequency and the corresponding optimal wavelet and scale is discussed, and a piecewise linear model of the base-2 logarithm of the frequency and the order of the wavelet is developed, in which different pieces represent different scales. As a result, the wavelet function and decomposition scale can be selected according to the oscillation frequency. Compared with the wavelet-based data compression method with a fixed wavelet scale for disturbance signals and the real-time data compression method based on exception compression and swing door trending for oscillations, the proposed method can provide high compression ratios and low distortion rates.

关键词： Data compression Oscillation Wavelet transform Wide-area measurement system(WAMS)

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In-situ Monitoring of Maximum and Average Chip Junction Temperature within Multichip IGBT power Modules Using Kelvin Emitter Voltage

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IEEE Journal of Emerging and Selected Topics in power Electronics 2025年

作者： Yang, Jianxiong Ran, Li Che, Yanbo Du, Mingxing Tianjin University of Technology Tianjin Key Laboratory of Control Theory and Applications in Complicated System Tianjin300384 China Chongqing University State Key Laboratory of Power Transmission Equipment and System Security and New Technology School of Electrical Engineering Chongqing400044 China University of Warwick School of Engineering CoventryCV4 7AL United Kingdom Tianjin University Key Laboratory of Smart Grid of Ministry of Education School of Electrical and Information Engineering Tianjin300072 China

Parallel configurations of power chips within a multichip IGBT power module (M-IGBT-PM) are employed to meet the required current and power ratings. When the internal chips of an M-IGBT-PM experience uneven temperature distributions and package aging, it becomes challenging to determine the maximum and average temperatures of the chips within the module. This paper investigates the relationship between four transient thermal-sensitive electrical parameters (T-TSEPs) derived from the Kelvin emitter voltage and the chip junction temperature, while establishing relevant mathematical models. It compares the sensitivity and linearity of these four T-TSEPs, and also assesses the influence of external gate resistance, bus voltage, and load current on each of them. A key innovation in this paper is the proposal of a method for monitoring the maximum and average temperatures across the chips within the M-IGBT-PM, which is not influenced by the load current. The experimental results suggest that the temperature derived from the quasi-turn-on delay time is a good approximation of the maximum chip temperature, whereas the temperatures predicted by the other T-TSEPs are nearer to the average temperature. © 2025 IEEE.

关键词： Insulated gate bipolar transistors (IGBT)

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Simplified equivalent models of large-scale wind power and their application on small-signal stability

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Journal of Modern power systems and Clean Energy 2013年第1期1卷 58-64页

作者： Nan DING Zongxiang LU Ying QIAO Yong MIN State Key Laboratory of Control and Simulation of Power System and Generation Equipments Tsinghua UniversityBeijing 100084China

With the rapid growth of grid-connected wind power penetration level,it is necessary to study the impacts of wind power on power system *** small-signal stability of power systems with large-scale wind power is explored using the eigenvalue analysis method.A prototype sample system,the two-synchronous-generator system with a wind farm,is proposed for theoretical ***,simplified models of wind turbines(WTs)and the corresponding equivalent models of wind farms are *** kinds of typical WT models,i.e.,squirrel cage induction generator,doubly-fed induction generator,and permanent magnet synchronous generator are ***,based on the simplified equivalent models,effects of large-scale wind farms on the electromechanical oscillation modes(EOMs)of synchronous systems are *** results indicate that wind farms of the three kinds of WTs have positive effects on ***,long transmission lines connecting wind farmto the systemmay produce negative effects on the small-signal stability of the system.

关键词： Wind turbine(WT) Small-signal stability Electromechanical oscillation mode(EOM) Simplified model Equivalent model

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Data-driven Transient Stability Assessment Model Considering Network Topology Changes via Mahalanobis Kernel Regression and Ensemble Learning

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Journal of Modern power systems and Clean Energy 2020年第6期8卷 1080-1091页

作者： Xianzhuang Liu Xiaohua Zhang Lei Chen Fei Xu Changyou Feng State Grid Corporation of China State Grid Jibei Electric Power Company the State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical EngineeringTsinghua University

Transient stability assessment(TSA)is of great importance in power system operation and *** of the usual tasks in TSA is to estimate the critical clearing time(CCT)of a given fault under the given network topology and pre-fault power ***-driven methods try to obtain models describing the mapping between these factors and the CCT from a large number of ***,the influence of network topology on CCT is hard to be analyzed and is often ignored,which makes the models inaccurate and *** this paper,a novel data-driven TSA model combining Mahalanobis kernel regression and ensemble learning is proposed to deal with the *** model is a weighted sum of several *** sub-model only uses the data of one topology to construct a kernel *** weights are determined by both the topological similarity and numerical similarity between the *** similarities are decided by the parameters in Mahalanobis distance,and the parameters are to be *** reduce the model complexity,sub-models within the same topology category share the same *** estimating CCT,the model uses not only the sub-model which the sample topology belongs to,but also other ***,it avoids the problem that there may be too few data under some *** also efficiently utilizes information of data under all the ***,its decision-making process is clear and understandable,and an effective training algorithm is also *** results on both the IEEE 10-machine 39-bus and a real system verify the effectiveness of the proposed model.

关键词： Transient stability assessment critical clearing time network topology change Mahalanobis kernel regression ensemble learning data-driven

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