Article
Energy & Fuels
Keyun Zhuang, Shehua Huang, Xiangqian Fu, Li Chen
Summary: This paper investigates the impact of hydraulic vibration on the stability and health of the hydro-turbine generator unit (HGU) and proposes a nonlinear mathematical model to capture the dynamic characteristics. The effects of different factors on the dynamic behavior of the system are analyzed, revealing important insights for the design and stability research of hydropower units.
Article
Green & Sustainable Science & Technology
Beibei Xu, Xingqi Luo, Monica Egusquiza, Wei Ye, Jing Liu, Eduard Egusquiza, Diyi Chen, Pengcheng Guo
Summary: The Francis hydro-turbine generator unit (FHTGU) is a typical nonlinear system with the coupling hydraulic, mechanical and electric subsystems, and its stability is affected by complex interactions, requiring new methods to cope with the new situation.
Article
Engineering, Multidisciplinary
Xinjie Lai, Huimin Huang, Bo Zheng, Dedi Li, Yue Zong
Summary: This study aims to investigate the stability and nonlinear dynamics of a hydro-turbine governing system with an asymmetric water diversion system using Hopf bifurcation theory. A full nonlinear mathematical model of the system is established, including all components and nonlinear head loss. The study explores the multi-stability characteristics of the system under load disturbance using stable domain analysis and numerical simulation. It also reveals the presence of multi-time scale oscillation and investigates its relationship with system multi-stability. The effects of system parameters and topological parameters on system stability are analyzed.
APPLIED MATHEMATICAL MODELLING
(2023)
Article
Engineering, Chemical
Huilai Sun, Ruichuan Li, Jikang Xu, Funing Xu, Bo Zhang, Xinyuan Dong
Summary: By establishing the differential equation and introducing fractional calculus theory, the vibration characteristics of the hydro-pneumatic suspension system were studied, resulting in a suitable fractional-order model. Simulation and experimental data showed that a fractional order of 0.9 can more accurately describe the motion characteristics of the suspension system.
Article
Engineering, Mechanical
Yousong Shi, Jianzhong Zhou, Xinjie Lai, Yanhe Xu, Wencheng Guo, Baonan Liu
Summary: This study investigated the vibrational stability and the sensitivity of shafting vibration to parameters of the unbalanced rotor bending-torsional coupling vibration of a hydro-turbine generator unit with arcuate whirl. A novel mathematical model was proposed, and the vibrational stability and sensitivity analysis were conducted through phase trajectory, Poincare map, frequency spectrum, and parameter bifurcation diagrams. The results showed that considering arcuate whirl led to changes in the vibration characteristics of the system and the sensitivity of vibrations to various parameters.
MECHANICAL SYSTEMS AND SIGNAL PROCESSING
(2021)
Article
Physics, Applied
Yuansheng Chen, Fei Tong
Summary: This paper focuses on the piecewise continuous time modeling of a hydro-turbine governing system in the process of shutdown transient, introducing piecewise nonlinear dynamic transfer coefficients. The impact of different shutdown laws on the quality of shutdown transient process is analyzed through numerical simulations, illustrating the nonlinear dynamic behaviors of the system. These methods and results are beneficial for the safe and stable operation of a hydropower station during shutdown transient.
INTERNATIONAL JOURNAL OF MODERN PHYSICS B
(2021)
Article
Automation & Control Systems
G. Narayanan, M. Syed Ali, Young Hoon Joo, R. Perumal, Bashir Ahmad, Hamed Alsulami
Summary: In this article, an adaptive fractional sliding-mode control (AFSMC) method is proposed to solve the Mittag-Leffler synchronization (MLS) problem in a fractional-order permanent magnet synchronous generator (FOPMSG)-based wind turbine system. The AFSMC method incorporates a fractional-order term into the new law for reaching the sliding mode, improving the control signal chattering and reducing the time required for the system to reach the sliding-mode surface. The robust MLS for the sliding-mode dynamics is ensured by the designed robust controller.
IEEE TRANSACTIONS ON SYSTEMS MAN CYBERNETICS-SYSTEMS
(2023)
Article
Mathematics, Applied
Wanquan Sun, Zhiqiang Guo
Summary: This paper presents a method for investigating the overall nonlinear dynamics of the coupled hydro-generator shaft-foundation system. A novel coupled dynamic mathematical model is developed, which simplifies the foundation system with an equivalent lumped-mass model and proposes a model for external random excitation. The advantages of this model lie in its convenience for capturing the key dynamic features of the coupled nonlinear system.
COMMUNICATIONS IN NONLINEAR SCIENCE AND NUMERICAL SIMULATION
(2021)
Article
Thermodynamics
Mohammad Esmaeili, Hamed Moradi
Summary: This paper investigates the control problem of ultra-supercritical once-through boiler (OTB) unit and proposes an accurate grey box multivariable coupled nonlinear model. The steam pressure, specific enthalpy, and active power are controlled by manipulating the fuel rate command, feedwater rate command, and throttle valve opening. The controller design takes into account operational parameter limitations and uncertainty sources. A nonlinear robust sliding mode controller is developed based on affine nonlinear control theory, and a linear H-infinity robust control is synthesized using MATLAB. The simulation results demonstrate that both designed controllers perform well in the presence of uncertainties and limitations, but the nonlinear controller has better performance. The deficiencies of a linear controller compared to the proposed robust controllers are also discussed.
Article
Energy & Fuels
Hamza Gasmi, Habib Benbouhenni, Sofiane Mendaci, Ilhami Colak
Summary: This paper improves the performance and efficacy of the super-twisting algorithm (STA) by using fractional calculus theory (FCT) and proposes a new form of the STA controller based on FCT technique for controlling the asynchronous generator (AG)-based wind power system (WPS). Objective functions are calculated to improve the characteristics and quality of reactive power, active power, and electric current. The proposed STA-FCT controller shows better performance and improves the features of indirect field-oriented control (IFOC) for AG-based WPS.
Article
Green & Sustainable Science & Technology
Pan Xu, Wenlong Fu, Qipeng Lu, Shihai Zhang, Renming Wang, Jiaxin Meng
Summary: This paper investigates the stability of hydro-turbine governing system (HTGS) with sloping ceiling tailrace tunnel (SCTT) and upstream surge tank (UST) considering nonlinear hydro-turbine characteristics (NHTCs). Firstly, a mathematical model based on a nonlinear seventh-order state equation is presented and verified by example analysis. Subsequently, the effect of HTGS parameters on the stability of the system is investigated through numerical simulation. Lastly, the coupling effect mechanism of SCTT and UST on stability under the effect of NHTCs is revealed by contrastive analysis. The results indicate that Ta, Kd, and Twt have a significant impact on the stability of HTGS, while F and Twy have a mild influence. The NHTCs are beneficial for stability under negative load disturbance but unfavorable under positive load disturbance. The coupling effect of SCTT and UST outperforms using SCTT or UST alone, and the introduction of SCTT improves stability and achieves smaller amplitude and lower frequency.
Article
Multidisciplinary Sciences
Zulqurnain Sabir, Salem Ben Said
Summary: In this study, a fractional order mathematical model based on the romantic relationship of the Layla and Majnun is numerically simulated using the Levenberg-Marquardt backpropagation neural networks. Fractional order derivatives provide more realistic solutions compared to integer order derivatives of the mathematical model. The model, consisting of four categories based on a system of nonlinear equations, is solved using a stochastic scheme with testing, authorization, and training data. The accuracy of the designed stochastic solver is improved by reducing the absolute error value, and its reliability is proven through various numerical measures.
SCIENTIFIC REPORTS
(2023)
Review
Computer Science, Artificial Intelligence
Habib Benbouhenni, Nicu Bizon, Mohamed I. Mosaad, Ilhami Colak, Abdelkadir Belhadj Djilali, Hamza Gasmi
Summary: This paper presents a new fractional-order fuzzy control strategy for DFIG-based multi-rotor wind energy systems, aiming to improve power quality and resistance to system parameter changes. Simulation results demonstrate the high performance and stability of the proposed strategy, even under system failure conditions.
EXPERT SYSTEMS WITH APPLICATIONS
(2024)
Article
Mathematics
Sergey Korchagin, Ekaterina Romanova, Denis Serdechnyy, Petr Nikitin, Vitaliy Dolgov, Vadim Feklin
Summary: The paper introduces a model of a layered hierarchically constructed composite, and conducts fractal analysis to assess the similarity properties at different scales and evaluate the complexity of the model quantitatively.
Article
Mathematics, Applied
Aqeel Ahmad, Muhammad Farman, Parvaiz Ahmad Naik, Nayab Zafar, Ali Akgul, Muhammad Umer Saleem
Summary: This paper analyzes and models bovine babesiosis disease using fractional calculus. The solution for the system is determined with different fractional derivatives, obtaining both analytical and special solutions. Numerical simulations show good agreement with theoretical outcomes, highlighting the importance of using fractional differential equations to model the disease and tick populations.
NUMERICAL METHODS FOR PARTIAL DIFFERENTIAL EQUATIONS
(2021)
Article
Energy & Fuels
Gongcheng Liu, Xudi Qiu, Jiayi Ma, Diyi Chen, Xiao Liang
Summary: This study investigates the stability performance of hydropower generation systems (HGS) during flexible operation. A dynamic model reflecting the characteristics of part-load conditions is established and coupled with a shafting system to investigate unit vibration. The results show that part-load operation leads to dynamic response fluctuations and possible ways to mitigate the instability are explored.
Article
Automation & Control Systems
Ziwen Zhao, Md Apel Mahmud, Pietro Elia Campana, Branislav Hredzak, Jie Luo, Diyi Chen, Beibei Xu
Summary: This study establishes a model of hydro-wind complementary generation system and investigates the propagation and interaction of harmonics in all components. The results show that the integration of hydroelectric generating system affects the harmonics, and the analysis of odd harmonics interactions identifies high-risk sources in the system. The findings are important for power quality evaluation of hydro-wind complementary generation system.
Article
Green & Sustainable Science & Technology
Pengfei Wang, Yuwen Deng, Huanhuan Li, Diyi Chen
Summary: This study reveals the coupling relationship between subsystems in the transient process of hydropower generation system through information flow, which is bidirectional and unaffected by load changes. The most strongly coupled part of the information is the parameters at the end of the path, which can change the dynamic characteristics of the system.
SUSTAINABLE ENERGY TECHNOLOGIES AND ASSESSMENTS
(2022)
Article
Physics, Multidisciplinary
Fei Chen, Wanfu Tian, Liyao Zhang, Jiazheng Li, Chen Ding, Diyi Chen, Weiyu Wang, Fengjiao Wu, Bin Wang
Summary: This paper proposes a transformer fault diagnosis method based on the combination of time-shift multiscale bubble entropy (TSMBE) and stochastic configuration network (SCN). The method successfully achieves accurate identification of different transformer state signals by using bubble entropy and TSMBE as fault feature extraction tools.
Article
Green & Sustainable Science & Technology
Tang Xin, Jiang Wei, Li Qiuying, Gaoyang Hou, Zhang Ning, Wang Yuchuan, Chen Diyi
Summary: The study analyzed the distribution of hydraulic losses in PAT using entropy generation theory. Results showed that energy losses mainly concentrate on guide vane, volute, and runner, with wall effect and velocity fluctuation as primary factors, guiding optimization of corresponding structures design.
SUSTAINABLE ENERGY TECHNOLOGIES AND ASSESSMENTS
(2022)
Article
Energy & Fuels
Rui Jia, Mengjiao He, Xinyu Zhang, Ziwen Zhao, Shuo Han, Jakub Jurasz, Diyi Chen, Beibei Xu
Summary: This study proposes a vibration avoidance strategy based on unit commitment to solve the vibration issues in hydro-wind-photovoltaic complementary generation systems. Multi-objective optimization is used to minimize water consumption, the frequency of crossing vibration zones, and the number of units involved in regulation. The results show that photovoltaic power is more effective than wind power in avoiding vibration zones.
Article
Thermodynamics
Xingjin Zhang, Pietro Elia Campana, Xiaojian Bi, Monica Egusquiza, Beibei Xu, Cong Wang, Hongyan Guo, Diyi Chen, Eduard Egusquiza
Summary: The hydro-wind-solar-storage bundling system plays a critical role in solving the spatial and temporal mismatch problems between renewable energy resources and the electric load in China. This study compares the role of technical and economic indicators of capacity configuration and explores the constraint relationship between electricity price and transmission constraints. Three screening principles of capacity configuration are proposed to reveal the techno-economic interaction.
ENERGY CONVERSION AND MANAGEMENT
(2022)
Article
Green & Sustainable Science & Technology
Xinyao Lan, Jiahui Jin, Beibei Xu, Diyi Chen, Monica Egusquiza, Jin-Hyuk Kim, Eduard Egusquiza, Nejadali Jafar, Lin Xu, Yuan Kuang
Summary: This study analyzes the influence of geometric and hydraulic parameters on the hydraulic characteristics of the Hydroelectric Generating Systems (HGS) with Coaxial Shaft Surge Tank (CSST) in the transient process. The results show that changing the diversion tunnel diameter and the impedance hole coefficient can adjust the hydraulic parameters and optimize the operational safety of the system.
Article
Green & Sustainable Science & Technology
Ziwen Zhao, Yichen Yuan, Mengjiao He, Jakub Jurasz, Jianan Wang, Monica Egusquiza, Eduard Egusquiza, Beibei Xu, Diyi Chen
Summary: This paper investigates the stability and efficiency performance of a pumped hydro energy storage system (PHESS) under various flexibility scenarios. A nonlinear model is established to study its stability and efficiency characteristics, and six flexibility scenarios are extracted based on historical power output. The results show that increased load variation negatively affects stability, with steeper parameter responses in the first 10 seconds compared to the later 30 seconds. Efficiency analysis reveals that friction loss is the dominant loss type in transient processes, except for the FL condition.
Article
Engineering, Mechanical
Wei Dong, Yan Dong, Jian Sun, Haichen Zhang, Diyi Chen
Summary: In this study, the IS 80-65-160 clean water centrifugal pump is investigated. By comparing the characteristics of flow, pressure pulsation, and radial force under different adjustment modes, it is found that frequency conversion adjustment can effectively reduce the amplitude of radial force pulsation, improving the stability of the pump.
IRANIAN JOURNAL OF SCIENCE AND TECHNOLOGY-TRANSACTIONS OF MECHANICAL ENGINEERING
(2023)
Article
Energy & Fuels
Weiyu Wang, Xunxin Zhao, Lijun Luo, Pei Zhang, Fan Mo, Fei Chen, Diyi Chen, Fengjiao Wu, Bin Wang
Summary: This paper proposes a rolling bearing diagnosis method by combining the attention entropy and adaptive deep kernel extreme learning machine (ADKELM). The method employs wavelet threshold denoising and empirical wavelet transform (EWT) to extract features, and optimizes the hyperparameters using the marine predators algorithm (MPA) for adaptive changes. The optimal ADKELM model is determined by analyzing the fault diagnosis performances.
Article
Energy & Fuels
Sha Li, Zezhou Cao, Kuangqing Hu, Diyi Chen
Summary: This paper focuses on the primary frequency regulation (PFR) performance of variable-speed pumped storage plants (VSPSPs) in isolated power systems. The hydraulic-mechanical-electrical numerical models are established to quantify the rotational speed stability of the pump-turbine and assess the effectiveness of variable-speed units (VSUs) in suppressing ultra-low frequency oscillation (ULFO). The results show that VSUs outperform fixed-speed units (FSUs) in the regulation process.
Article
Energy & Fuels
Shuo Han, Mengjiao He, Ziwen Zhao, Diyi Chen, Beibei Xu, Jakub Jurasz, Fusheng Liu, Hongxi Zheng
Summary: A day-ahead scheduling model is proposed for a hydro-wind hybrid power generation system, considering the power regulation flexibility and frequency response flexibility. The study shows that utilizing the flexibility of hydropower can reduce frequency deviation, wind power curtailment, and load loss. Decision makers can use the flexibility supply capacity of the hydropower station to determine the connected wind power capacity and system load for comprehensive benefits.
Article
Engineering, Mechanical
Pengfei Wang, Yixuan Guo, Zhenkun Xu, Weihao Wang, Diyi Chen
Summary: The hydropower generation system is a complex nonlinear system with hybrid state responses. This study proposes a data mining and data prediction strategy based on information causality and the PageRank algorithm, which is validated using a 250 MW hydropower unit. The results show that considering the information transfer sequences between variables improves prediction accuracy.
MECHANICAL SYSTEMS AND SIGNAL PROCESSING
(2023)
Article
Thermodynamics
Yang Zhang, Wei Jiang, Yuchuan Wang, Ye Li, Diyi Chen
Summary: Pump-turbines are significant in modern power systems as they ensure power system frequency stability and compensate for the intermittent nature of new energy sources. The study investigates the vortex characteristics and pressure fluctuation intensity of the pump-turbine model operating in pump mode using the Large Eddy Simulation (LES) method. Results indicate that the impeller's wake vortex greatly influences the pump-turbine's internal flow field, originating from the vortex structure near the blade's suction surface. The distribution of trailing edge shedding vortex and shock vortex around the tongue is closely related to the impeller's wake vortex. The research emphasizes the importance of improving the pump-turbine's vortex structure for safe and stable operation.
PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART A-JOURNAL OF POWER AND ENERGY
(2023)
