31 August 2025, Volume 45 Issue 4

  

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  Characteristics of Conductor Ice Shedding under Time-varying Aerodynamic Loads

  ZUO Lindong, LI Lin, JI Kunpeng, WANG Xiaochuan

  2025, 45(4): 1-8. https://doi.org/10.19718/j.issn.1005-2992.2025-04-0001-08

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  Under external forces or ambient temperature changes,ice accretion on transmission line conductors may shed,inducing large-amplitude conductor vibrations.This can subsequently lead to structural damage or flashover trip faults.Previous research primarily focused on the vibration characteristics induced by ice shedding itself.When wind load effects were considered in some studies,the wind load was typically assumed constant throughout the shedding process,neglecting its time-varying characteristics and their influence on the conductor's ice shedding response.This study employs the User Element subroutine in ABAQUS to describe the time-varying aerodynamic loads and investigates the impact of wind load variations on the ice shedding motion characteristics of conductors based on the finite element method.Taking typical crescent-shaped ice accretion as the research object,the dynamic characteristics of conductor ice shedding under time-varying aerodynamic loads were simulated,with a focus on the influence of different wind speeds,wind load types （i.e.，mean wind and fluctuating wind），and ice shedding rates on conductor jump height,horizontal swing amplitude,and motion trajectory.The study reveals that fluctuating wind significantly influences the displacement trajectory of conductor ice shedding compared to mean wind.Under identical ice shedding rates,fluctuating wind increases both the conductor's jump height and horizontal swing range.The research findings provide support for accurately determining the motion characteristics of conductors during ice shedding and for designing electrical clearances in transmission lines.
  
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  An Analytical Study of Sub-synchronous Oscillation Characteristics of Power System with GFL-GFM Mixed Wind Turbine Based on Grid Energy

  LIU Cheng, ZHOU Ling, LI Wenbiao, SONG Yuman

  2025, 45(4): 9-17. https://doi.org/10.19718/j.issn.1005-2992.2025-04-0009-09

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  In recent years,with the "double carbon"goal proposed and the construction of new power system,the grid-forming control has been widely concerned by many scholars.In order to study the effect of GFM control on sub-synchronous oscillation of new energy power system,the mode energy function of GFM and GFL wind turbine is constructed based on network quantity measurement.Based on Prony-Levenberg-Marquardt （Prony-LM）method,the mode energy is identified and the mode energy components in different frequency bands are obtained.According to the amplitude of the mode energy,the participation degree of different modes in the system oscillation is obtained,and the mode with high energy amplitude is found to be the dominant oscillation mode of the system,which provides a new aspect for the damping of oscillation.The influence of grid-forming control on sub-synchronous oscillation of hybrid power system is further studied,and it is found that the access of grid-forming control will worsen the oscillation of the system,which is not conducive to the safety and stability of the system,and also lays a foundation for the subsequent sub-synchronous oscillation regulation of the net-grid type hybrid power system.Finally,the effectiveness of the proposed method is verified by MATLAB/Simulink simulation software.
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  Evaluation of Electricity Price Package Based on IFAHP-CRITIC CombinationWeighting Method and Improved TOPSIS 

  XIAO Bai, LIU Jiatao, YANG Shiwei

  2025, 45(4): 18-25. https://doi.org/10.19718/ j.issn.1005-2992.2025-04-0018-09

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  Evaluation of Electricity Price Package Based on IFAHP-CRITIC Combination Weighting Method and Improved TOPSIS In order to evaluate complex and diverse electricity pricing packages more reasonably and promote the development of electricity pricing packages to adapt to the changes in China's electricity market,a method based on Intuitionistic Fuzzy Analytic Hierarchy Process （IFAHP）and Criterion Importance Through Intercriteria Correlation （CRITIC）considering the needs of multiple parties in the electricity market is proposed The electricity price package evaluation method is based on the combination weighting method and the improved Technique for Order Preference by Similarity to an Ideal Solution （TOPSIS）。Firstly,determine the package evaluation indicators from a market perspective；Then,subjective and objective weights were assigned to each indicator using the IFAHP weighting method and CRITIC objective weighting method,respectively,and the comprehensive weights of each indicator were determined using Nash equilibrium；Finally,based on Grey Relational Analysis （GRA），TOPSIS is improved and the GRA Euclidean distance measure is used to evaluate the package.The calculation results show that this method can accurately and scientifically complete the evaluation of electricity price packages.
  
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  A Optimization Strategies for Yaw Control in Wind Turbine Generators 

  ZHANG Lei, JIN Lianhua, SHEN Jiang, CAO Shanqiao, LI Junfeng, HAN Siyu, FENG Zhengcong, ZHANG Lidong

  2025, 45(4): 26-32. https://doi.org/10.19718/j.issn.1005-2992.2025-04-0026-07

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  In the context of addressing global climate change and reducing carbon emissions,wind power,as a key component of clean energy,is receiving increasing attention.With the rapid growth of wind power installations,there is a trend towards larger and more efficient wind turbine generators.Yaw control strategies play a critical role in enhancing wind energy capture efficiency,reducing operational and maintenance costs,and extending the lifespan of wind turbines,thus serving as essential means to improve the economic viability and sustainability of wind power.This paper systematically reviews the current research status and development trends in yaw control strategies for wind turbines,with a focus on the structural design and aerodynamic characteristics of yaw systems.It particularly examines the impacts of various control strategies on turbine fatigue loads,wind energy capture efficiency,and wake effects.Finally,based on current research trends,the paper proposes directions and technical pathways for optimizing yaw control strategies,offering insights and references for achieving efficient yaw control in future wind turbines.
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  Prediction of Void Fraction of Fluctuating Vibration Gas-liquid Two-phase Flow in a Horizontal Pipe Based on Whale Optimization Algorithm and Machine Learning 

  LIU Qichao, ZHANG Shibo, ZHOU Yunlong, ZHANG Gang

  2025, 45(4): 33-41. https://doi.org/10.19718/j.issn.1005-2992.2025-04-0033-09

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  Floating nuclear power platforms are frequently in movement under the action of waves.The internal gas-liquid two-phase flow characteristics change under the influence of the motion.The accurate prediction of void fraction in gas-liquid two-phase flow under fluctuating vibration is of great significance to the safe and stable operation of floating nuclear power platforms.The void fraction of gas-liquid two-phase flow in a horizontal tube under fluctuating vibrations was measured for different tube diameters,vibration frequencies,and amplitudes.The void fraction was predicted using a BP neural network.The BP neural network was optimized using whale optimisation algorithm based on chaotic mapping and adaptive weights （CA-WOA-BP）。The results show that the BP neural network is more effective in predicting the void fraction of gas-liquid two-phase flow in a horizontal pipe under fluctuating vibration.The optimisation algorithm can further improve its prediction accuracy and stability.The accuracy is increased to 91%.Meanwhile,a comparison of the prediction results with the existing correlation formula was made.It is found that the optimised BP neural network has smaller prediction error and better applicability to the prediction under fluctuating vibration.It provides an effective method for the prediction of the gas content rate under this condition.
  
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  Modeling and Simulation Analysis of Emergency Power Generation Units for Grid-forming PEMFC

  XIE Jiabing, NI Defu

  2025, 45(4): 42-52. https://doi.org/10.19718/j.issn.1005-2992.2025-04-0042-11

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  In response to the lack of analysis on the dynamic response characteristics and grid construction ability of PEMFC as a low-carbon emergency power generation unit,this paper conducts modeling and simulation analysis of grid-forming PEMFC emergency power generation units.Establish static and dynamic response models for PEMFC with thermal management system,and propose a cascaded grid-forming inverter grid control strategy.Based on MATLAB/ SIMULINK,a simulation model of a 150kW grid-forming PEMFC power generation unit was constructed.Through island mode and system load change scenarios,the characteristics of the grid-forming PEMFC emergency power supply providing damping and inertia for the system were verified,improving system stability and adapting to the needs of various complex scenarios.
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  An Active Frequency Response Control Strategy for AC/DC Hybrid Grid Based on Coordination of Three Defense Lines

  LI Zifeng , CHU Hongchuan , SUN Qiao, LI Hongwei, FU Shaowen, CHEN Ruochen, ZHAO Boqun, LI Weidong

  2025, 45(4): 53-62. https://doi.org/10.19718 / j.issn.1005-2992.2025-04-0053-10

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  After power disturbances occur in power systems, the frequency response presents significant spatial -temporal characteristics. The current situation of asynchronous frequency response in different areas determines that there is room for improvement in the frequency regulation capability of interconnected power systems. Due to the optimal operation of power systems through multi - stage coordinated operation ， this paper proposes a multi - stage coordinated active frequency response （CAFR） control strategy based on three lines of defense for frequency stability of power systems ， aiming at safety and economic coordination. In the prevention control stage ， the regulation capacity is reserved by purchasing the frequency regulation capacity in advance ； In the emergency control stage ， the frequency response spatial -temporal characteristics are utilized to enhance the frequency regulation capability of the system through feedforward active control； In the correction control stage ， penalty items are set to avoid affecting system safety and triggering under frequency load shedding （UFLS）。 Both numerical example analysis and simulation verification show that the proposed active frequency response（AFR） control strategy for AC/DC hybrid power systems based on three lines of defense coordination is superior to the passive frequency response （PFR） mode in terms of security ， and is more superior to the single stage operation control in terms of economy, with significant improvement in overall control effectiveness.
  
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  Risk Resistance and Flexible Coordination of Heterogeneous EnergyFlow System Considering Supply and Demand Relationship

  PAN Chao , Xu Yancheng, Tang Hua , Dong Tao , Zhang Jing

  2025, 45(4): 63-73. https://doi.org/10.19718 / j.issn.1005-2992.2025-04-0063-12

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  Aiming at the operation characteristics of the electricity-gas-heat heterogeneous energy flow system undelextreme weather in Shandong, an effective risk collaborative defense strategy is formulated.The energy flow couplingdevice is used to realize the interaction of heterogeneous energy flow,and the flexible resources such as controllableindustrial load and mobile energy storage unit are excavated.Considering the relationship between supply and demandthe risk resistance strategy is proposed ,the evaluation index of imbalance degree is constructed and the types of riskscenarios are divided,the risk resistance scheme is formulated ,and the auxiliary decision-making system is formed byusing the carbon flow description of risk scenarios.Based on the comprehensive benelits of economic operation cost,fexible regulation and control ability ,safety and stability and risk carbon emission,a colaborative resistance operationmodel is built. Finally, a regional system in Shandong Province is taken as the simulation object to analyze thecomprehensive benelits of the system 's coordinated resistance to different degrees of supply and demand imbalanceand the low-carbon efect of the system 's coordinated resistance is deseribed by carbon flow.The results show that theuse of energy flow coupling, devices and flexible resources can effectively improve the system ’s ability to resist riskinterference ,and the risk resistance scheme is conducive to improving the imbalance between supply and demand of the system, which verifies the rationality and feasibility of the collaborative resistance operation model based on risk resistance strategy.
  
  
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  Source-load Collaborative Optimal Dispatch Considering Green Certificate-carbon Trading Coupling and Flexible Electrical/Thermal Loads

  XING Xiaomin, WANG Xiangchen, LI Yitao, ZHENG Xuerui

  2025, 45(4): 74-85. https://doi.org/10.19718 / j.issn.1005-2992.2025-04-0074-12

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  In the context of the " dual carbon" goal,in order to more elliciently reduce carbon emisions and improvethe consumption rate of new energy, a comprehensive energy system source load coordination optimization schedulingstrategy considering a stepped green certilicate carbon trading interaction mechanism and electric and thermal flexibleloads is proposed. Firstly ,establish a tiered green certificate and tiered carbon trading interaction model, linking greencertificate trading and carbon trading through the carbon reduction emissions behind the green certificate; Then , aHexible electric and thermal load is added to the load side, considering both reducible and transferable loads, whileutilizing the thermal inertia of the thermal system and considering user comfort to construct a flexible thermal loadmodel; Finally, establish a source load collaborative scheduling model: flexibly adjust the load side through flexibleloads,thereby affecting the power generation arrangement on the source side and the value of the green certificatecarbon trading mechanism.l our scenarios were used to verily its elfectiveness ,and through case analysis ,it was verifiecthat the use of electric and thermal flexible loads can reduce the cost of green certificates and carbon trading on thesource side.This source load synergy effectively improves the consumption rate of new energy ,fully demonstrating theeffectiveness of the model proposed in this paper.
  
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  The Optimal Operation of Regional Integrated Energy System Consideringthe Uncertainty of Source Load and the Operation Characteristicsof Equipment under Varying Operating Conditions

  YAN Gangui, WANG Boyan, WANG Mingwei

  2025, 45(4): 86-96. https://doi.org/10.19718 / j.issn.1005-2992.2025-04-0086-11

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   Building Regional Integrated Energy Systems ( RlES) is an ellective way to cope with the high proportion ofrenewable energy interconnection. However, the eiciency of RlES scheduling scheme is easily alfected by theuncertainty of source load and the variable operating conditions of different energy conversion equipment.In this papera random optimization operation method is proposed. Firstly,the Dynamic Energy Hub ( DEH) model is created, theequipment model and objective function are established ,and the RlES optimization scheduling method considering theequipment's variable operating conditions is proposed. Secondly , the source load uncertainty is characterized by K.means clustering method, and the typical system operation scenario is obtained. Finally, combined with the DEHmodel, the optimal scheduling scheme and the capacity configuration results of each energy conversion equipment aredetermined.'The optimization results show that the proposed method can rationally dispatch multiple types of energy inthe regional integrated energy system, improve the operating economy of the system and the absorption capacity ofrenewable energy ,and reduce carbon emissions
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  A Partitioning Strategy Based on Statistical Distance and Dynamic ReactivePower Reserve for Stability in Distribution Networks with High PV Penetration

  WANG Jian, SUN Yufeng, WANG Jieyan

  2025, 45(4): 97-107. https://doi.org/10.19718 / j.issn.1005-2992.2025-04-0097-11

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  With the high penetration of photovoltaic ( PV) systems into distribution networks, the randomness andvolatility of PV output have made power flow in the grid more complex and variable.The random variation in activepower output of PV systems under constant power factor control also leads to random changes in reactive power outputCurrently, reactive power/voltage partitioning results based on line reactive power flow are subject to frequent changesdue to the variability of reactive power flow,causing continuous changes in partitioning results and frequent switchingof some nodes between partitions, which degrades voltage control performance.'This paper proposes a stable reactivpower/ voltage partitioning method based on probabilistic statistical distance to define a new electrical distance. Firstthe Gaussian Mixture Model ( GMM) is used to characterize the stochastic features of PV active power output , and thereactive power output characteristics are derived based on the power factor, "Then , probabilistic power flow calculation isperformed using the Monte Carlo Simulation ( MCS) method to obtain the random distribution of node voltages in thedistribution network.Subsequently, the Earth Mover's Distance ( EMlD) is applied to define the statistical distancebetween nodes based on the obtained voltage distributions ,and a new electrical distance is defined by combining nodevoltage sensitivity. Finally , the Affinity Propagation ( AP) clustering algorithm and dnamic reactive power reserveconstraints are used to obtain the partitioning, results. Simulation results based on the lEEE 33- node systemdemonstrate that the proposed partitioning method exhibits good eflectiveness and stability in scenarios with high PVpenetration ,effectively addressing the challenges posed by frequent power flow variations.
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  An Economic and Low-carbon Dispatch Strategy for Community IntegratedEnergy Systems Considering Electricity-heat Carbon Emission Factors

  WANG Yijun, LU Ziheng, HE Yuzhe, ZHANG Jinming

  2025, 45(4): 108-120. https://doi.org/10.19718 / j.issn.1005-2992.2025-04-0108-13

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  Although the electricity carbon emission factor can elfectively reveal the carbon potential across differenttimes of the day, encouraging the shifting of flexible electric load usage to achieve peak shaving, valley filling, andpower absorption, it lacks sullicient stimulation for the bi- directional conversion flexibility of electric - heatsubstitutable loads.Based on this , this paper proposes an economic and low-carbon dispatch strategy for communityintegrated energy systems guided by electricity-heat carbon emission factors.In the first stage the economic dispatch olthe community integrated energy system is conducted to determine the type and output of energy-supplying equipmentat each time interval.based on which the daily peak-valey trends of electricity and heat carbon emission factors arecalculated.In the second stage ,homogeneous load time-sequence optimization is carried out according to the trends oleach carbon emission factor , while heterogeneous load energy type optimization is performed based on the differencesbetween electricity and heat carbon emission factors.'The case study demonstrates that the proposed strategy can furtheiexploit the flexibility of electric -heat substitutable loads, improving economic efficiency, and offering advantages inpromoting power absorption , reducing carbon emissions , and alleviating transformer overload.