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Cascading Failure Screening Based on Gradient Boosting Decision Tree for HVDC Sending-End systems with High Wind power Penetration

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IEEE Transactions on power systems 2025年

作者： Liu, Tianhao Yan, Jiongcheng Liu, Yutian Chung, Chi Yung Shandong University Key Laboratory of Power System Intelligent Dispatch and Control of Ministry of Education Jinan China The Hong Kong Polytechnic University Department of Electrical and Electronic Engineering Kowloon Hong Kong

In LCC-HVDC sending-end AC systems, cascading failures combined with the dynamic response of wind turbines (WTs) can lead to HVDC commutation failures. The resulting transient voltage disturbances cause WT tripping in sending-end systems. Cascading failures that involve the interaction between WTs and HVDC significantly limit the wind power transmitted by HVDC systems. This paper proposes an online cascading failure screening method based on gradient boosting decision tree (GBDT) for HVDC sending-end systems with large-scale WTs. First, a confidence level-based WT tripping model is proposed for cascading failure risk assessment considering a typical cascading failure propagation pattern. Then, Monte Carlo tree search is improved using a contrastive pruning technique to generate evenly distributed samples of cascading failures offline. Dynamic insecure scenarios are quickly identified using an improved support vector machine. Finally, GBDT is utilized to screen for cascading failures online by predicting subsequent high-risk failures using operating features. A dynamic weighting technique is proposed for GBDT to improve the fault prediction accuracy. Simulation results of a modified New England test system and the Ningxia provincial power grid in western China demonstrate that the proposed method can quickly screen for cascading failures considering the dynamic interaction between WTs and HVDC. © 1969-2012 IEEE.

关键词： Risk assessment

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Suppression of Phase Current Ripple and Torque Harmonics in Four-Module PMSM with Asymmetric Mutual Inductance

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IEEE Transactions on power Electronics 2025年

作者： Liu, Kaiyuan Li, Chi Zheng, Zedong Li, Yongdong Tsinghua University State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Beijing100084 China

In N-module motors, uniform carrier phase shifting (UCPS) by 2π/N between modules can effectively suppress torque harmonics caused by high-frequency switching of power devices. In multi-module motors with fractional-slot concentrated winding, the mutual inductance between adjacent windings is higher than that between non-adjacent windings. Although the conventional UCPS can reduce the torque sideband harmonics synthesized by the four modules, this asymmetric mutual inductance (AMI) paradoxically increases phase current ripple in each sub-module, leading to higher system losses. Aiming at this problem, this paper derives the mathematical model of N-module motor with AMI, analyzes the limitations of the traditional UCPS method that increases the phase current ripple. For different optimization objectives, two carrier phaseshifting angle optimized strategies are proposed to achieve integrated suppression of torque sideband harmonics and intramodule phase current ripples, with a genetic algorithm improving optimization speed. A threshold coefficient is introduced to achieve a tradeoff between phase current ripple and q-axis current harmonics, which can be adjusted to prioritize objectives based on user requirements. To enhance algorithm adaptability, the paper further investigates model variations under uneven torque distribution in sub-healthy states and proposes an improved comprehensive optimization algorithm, limiting torque sideband harmonics and current ripple in both healthy and sub-healthy conditions. Finally, the proposed algorithm is validated experimentally by a four-module permanent magnet synchronous motor. © 2025 IEEE.

关键词： Genetic algorithms

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Distributionally robust electricity-carbon collaborative scheduling of integrated energy systems based on refined joint model of heating networks and buildings

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Renewable Energy 2025年 251卷

作者： Chen, Haipeng Song, Jianzhao Li, Zhiwei Shui, Siyuan Key Laboratory of Modern Power System Simulation and Control & Renewable Energy Technology Ministry of Education Northeast Electric Power University Jilin 132012 China Department of Electrical Engineering Northeast Electric Power University Jilin 132012 China School of Automation and Engineering Northeast Electric Power University Jilin 132012 China Northeast Electric Power University Jilin 132012 China

The rapid increase in the grid integration demand of intermittent renewable energy (RE) has raised higher requirements for the flexible regulation and energy storage capacity of integrated energy systems (IES) with combined heat and power (CHP) units. To solve the issues of efficient accommodation of high proportion RE and low-carbon economic operation of the system, this study proposes an optimal scheduling method for IES based on a refined joint model of heating networks and buildings. Firstly, a refined thermal energy transmission model integrating heating networks and buildings is established to accurately depict the dynamic thermal energy transmission process within the system. Then, this paper proposes an electricity - carbon demand response considering the dynamic carbon emission factor, guiding users to use electricity in a low-carbon way. A distributionally robust optimization (DRO) scheduling model is established to quantify the impact of RE output uncertainty, which is efficiently solved using the column and constraint generation algorithm. The simulation results show that the proposed DRO model ensures the robustness of system operation while improving low-carbon economic benefits. Notably, the RE consumption rate is increased by 9.52 % compared with traditional scheduling methods, which provides an essential reference for promoting the sustainable development of IES. © 2025

关键词： Thermal energy

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Generating High-Temperature Polymer Dielectrics with a Graph Convolution and Reinforcement Learning Framework

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Journal of Physical Chemistry C 2025年第22期129卷 10020-10026页

作者： Liu, Di-Fan Dong, Wen-Zhuo Wang, Xin-Jie Zhong, Shao-Long Dang, Zhi-Min State Key Laboratory of Power System Operation and Control Department of Electrical Engineering Tsinghua University Beijing100084 China

Generating molecular structures with certain desired properties is a fundamental problem for material science research. Deep learning models have demonstrated big potential to identify novel materials by exploring large chemical spaces efficiently. Here, we demonstrate the generation of hypothetical polymers with a high glass-transition temperature (Tg) and a wide band gap (Eg) using a general graph convolutional network-based model through reinforcement learning. Two forward property prediction models on Tg and Eg are employed to provide domain-specific rewards. We further incorporate prior knowledge in the form of adversarial rewards given by a generative adversarial network framework via a data set of exemplar polymer structures. The domain-specific rewards and adversarial rewards are optimized in a reinforcement learning framework through policy gradient methods. Rules of chemistry are incorporated in the molecule generation environment as hard constraints. The generation process is guided to generate promising high-temperature polymer dielectrics for energy storage applications by property targeting and constrained property optimization. This work demonstrates potential for exploring large chemical spaces for the discovery of polymers with desirable properties. © 2025 American Chemical Society.

关键词： Deep reinforcement learning

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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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Ferrite Core Magnetothermal Equilibrium Design for Wireless power Transfer systems Using a Novel Differential Regulation Coil

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IEEE Transactions on power Electronics 2025年

作者： Wei, Yize Zhang, Xian Chen, Zhixin Xu, Fei Tse, Chi K. Hebei University of Technology State Key Laboratory of Intelligent Power Distribution Equipment and System Tianjin300401 China Hebei University of Technology Hebei Key Laboratory of Equipment and Technology Demonstration of Flexible DC Transmission Tianjin300401 China City University of Hong Kong Department of Electrical Engineering 999077 Hong Kong

The safe operation and durability of a wireless power transfer (WPT) system are challenged as the power level increases due to the uneven magnetothermal distribution in the ferrite core. However, existing research has rarely taken this issue into consideration. In this paper, a novel differential regulation (DR) coil is designed and installed in the magnetic coupled structure (MCS) to achieve a uniform magnetothermal distribution of the ferrite core. To provide a theoretical foundation for the DR coil design and to evaluate the effectiveness of the proposed magnetothermal equilibrium design, a comprehensive magnetothermal equilibrium formula (MEF) is given. An 11.1 kW/85 kHz experimental prototype is built to validate the magnetothermal equilibrium method. Results show that utilizing the proposed DR coil, the maximum temperature of ferrite core and the leakage flux can be reduced by 20.0% and 18.2%, respectively. Moreover, the spatial distribution uniformity of the temperature on the ferrite core can be improved by 56.3%, and the uniformity of the spatial distribution of the magnetic flux density can be improved by 10.7%. Overall, the magnetothermal equilibrium of ferrite cores has increased by 28.1%. © 1986-2012 IEEE.

关键词： Magnetic leakage

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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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power-absorption mechanism and coupling effects in dual-wavelength laser-sustained plasma

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Physical Review Applied 2025年第5期23卷 054083-054083页

作者： Dongheyu Zhang (张东荷雨) Jinbao Liu (刘金宝) Yangyang Fu (付洋洋) Department of Electrical Engineering Tsinghua University 100084 Beijing China State Key Laboratory of Power System Operation and Control Department of Electrical Engineering Tsinghua University 100084 Beijing China

Dual-wavelength laser-sustained plasma (LSP), which absorbs energy from lasers with two different wavelengths, is promising as a high-performance light source for wafer optical inspection; however, the mechanisms of power absorption from two lasers are still not well understood. Here a fully coupled laser-thermal-hydrodynamic fluid model is established to investigate the formation characteristics of dual-wavelength LSP. The model is validated by our comparing the laser power absorption results from the simulation and those from experiments. The simulation results show that the near-infrared (915-nm) laser heats a relatively large area of the LSP. In contrast, the visible (435-nm) laser can penetrate the LSP bulk and deposit energy mainly at the focal point, resulting in a smaller, hotter, and higher-radiance LSP core. The time-dependent evolution of the dual-wavelength LSP and the energy components of laser power absorption are presented; moreover, the coupling effects of the two lasers are observed. The near-infrared laser can sustain a large-area background plasma at a relatively low temperature (approximately 15 000 K), which increases the visible laser power absorption at the LSP core, reaching the highest temperature of approximately 30 000 K. The results from this work indicate that dual-wavelength LSP can be a competitive candidate for developing high-performance broadband and high-intensity radiative light sources.

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A Risk-Averse Just-In-Time Scheme for Learning-Based operation of Microgrids With Coupled Electricity-Hydrogen-Ammonia Under Uncertainties

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IEEE Transactions on Sustainable Energy 2025年

作者： Li, Longyan Ning, Chao Pan, Guangsheng Zhang, Leiqi Gu, Wei Zhao, Liang Du, Wenli Shahidehpour, Mohammad Shanghai Jiao Tong University Department of Automation Shanghai200240 China Ministry of Education of China Key Laboratory of System Control and Information Processing Shanghai200240 China School of Electrical Engineering Southeast University Nanjing210096 China Zhejiang Key Laboratory of Distributed Generations and Microgrid Technology State Grid Zhejiang Electric Power Research Institute Hangzhou310014 China Key Laboratory of Smart Manufacturing in Energy Chemical Process Ministry of Education East China University of Science and Technology China Department of Electrical and Computer Engineering Illinois Institute of Technology ChicagoIL60616 United States

This paper proposes a Risk-Averse Just-In-Time (RAJIT) operation scheme for Ammonia-Hydrogen-based Micro-Grids (AHMGs) to boost electricity-hydrogen-ammonia coupling under uncertainties. First, an off-grid AHMG model is developed, featuring a novel multi-mode ammonia synthesis process and a hydrogen-ammonia dual gas turbine with tunable feed-in ratios. Subsequently, a state-behavior mapping strategy linking hydrogen storage levels with the operation modes of ammonia synthesis is established to prevent cost-ineffective shutdowns. The proposed model substantially improves operational flexibility but results in a challenging nonlinear fractional program. Based upon this model, a data-driven RAJIT scheme is developed for the real-time rolling optimization of AHMGs. Unlike conventional one-size-fits-all schemes using one optimization method throughout, the data-driven RAJIT intelligently switches between cost-effective deterministic optimization and risk-averse online-learning distributionally robust optimization depending on actual risk profiles, thus capitalizing on the respective strengths of these two optimization methods. To facilitate the solution of the resulting nonlinear program, we develop an equivalent-reformulation-based solution methodology by leveraging a constraint-tightening technique. Numerical simulations demonstrate that the proposed scheme guarantees safety and yields an overall cost reduction up to 14.6% compared with several state-of-the-art methods. © 2025 IEEE.

关键词： Ammonia

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A constant quasi-zero stiffness isolator with tension springs to isolate vibrations with ultralow frequency

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International Journal of Non-Linear Mechanics 2025年 175卷

作者： Zhao, Feng Ji, J.C. Cao, Shuqian Zheng, Jingyang Luo, Quantian Department of Mechanics Tianjin University Tianjin300354 China Tianjin Key Laboratory of Nonlinear Dynamics and Control National Key Laboratory of Vehicle Power System Tianjin300354 China College of Mechanical and Electrical Engineering Henan Key Laboratory of Intelligent Manufacturing of Mechanical Equipment Zhengzhou University of Light Industry Zhengzhou450002 China School of Mechanical and Mechatronic Engineering University of Technology Sydney NSW2007 Australia College of Vehicle and Traffic Engineering Henan University of Science and Technology Luoyang471003 China

Many types of quasi-zero stiffness (QZS) isolators have been developed to isolate vibrations with low frequencies. However, isolating vibrations with ultralow frequency as low as 1 Hz is still a great challenge even in laboratory tests due to the high damping of QZS prototypes. To address this issue, a novel isolator with intrinsically light damping is proposed by configurating tension springs and oblique bars. The linear or nonlinear negative stiffness generated by the horizontal tension springs and oblique bars counteracts the linear positive stiffness of the vertical tension springs to obtain the QZS-related features including nonlinear QZS, constant positive or negative dynamic stiffness, constant QZS, and constant zero stiffness. Two QZS conditions are derived and the influence of parameters on QZS is thoroughly studied. The proposed isolator with tension springs has obvious differences from the previous isolator with compression springs in terms of QZS conditions, as well as force and stiffness expressions. Then, the displacement transmissibility is calculated by using the increment harmonic balance method and the continuous arc-length algorithm, which is verified by the classical harmonic balance method. These methods have the same prediction result. Finally, a prototype is fabricated and tested. The smoother force curves with constant QZS and the higher transmissibility amplitude can be obtained in tests compared to the previous isolator with compression springs under the same configuration parameters, which verifies the theoretical formulations of the proposed isolator with light damping. The prototype is further improved by replacing linear bearings with sliders to reduce the frictional effects. As a result, vibrations with ultralow frequencies lower than 1 Hz are successfully isolated. The proposed isolator has a wider frequency band and lower transmissibility than the previous isolator with compression springs. This study offers an effective method of de

关键词： Damping

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