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Grid Strength Assessment Method for Evaluating Small-signal Synchronization Stability of Grid-following and Grid-forming Converters Integrated systems

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Journal of Modern power systems and Clean Energy 2025年第1期13卷 55-65页

作者： Qianhong Shi Wei Dong Guanzhong Wang Junchao Ma Chenxu Wang Xianye Guo Vladimir Terzija Key Laboratory of Power System Intelligent Dispatch and Control of Ministry of Education School of Electrical EngineeringShandong UniversityJinan 250061China Electric Power Research Institute State Grid Zhejiang Electric Power Co.Ltd.Hangzhou 310014China School of Engineering Newcastle UniversityNewcastle upon TyneUK

Oscillations caused by small-signal instability have been widely observed in AC grids with grid-following(GFL)and grid-forming(GFM)*** generalized short-circuit ratio is commonly used to assess the strength of GFL converters when integrated with weak AC systems at risk of *** paper provides the grid strength assessment method to evaluate the small-signal synchronization stability of GFL and GFM converters integrated ***,the admittance and impedance matrices of the GFL and GFM converters are analyzed to identify the frequency bands associated with negative damping in oscillation modes dominated by heterogeneous synchronization ***,based on the interaction rules between the short-circuit ratio and the different oscillation modes,an equivalent circuit is proposed to simplify the grid strength assessment through the topological transformation of the AC *** risk of sub-synchronization and low-frequency oscillations,influenced by GFL and GFM converters,is then reformulated as a semi-definite programming(SDP)model,incorporating the node admittance matrix and grid-connected device *** effectiveness of the proposed method is demonstrated through a case analysis.

关键词： Grid-following converter grid-forming converter grid strength assessment small-signal stability

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Partial Solution Operator Discretization-Based Methods for Efficiently Computing Least-Damped Eigenvalues of Large Time Delayed power systems

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CSEE Journal of power and Energy systems 2025年第2期11卷 671-682页

作者： Hua Ye Xiaofan Jia Muyang Liu Yutian Liu Sicong Zhang Key Laboratory of Power System Intelligent Dispatch and Control of Ministry of EducationShandong UniversityJinan 250061China School of Electrical Engineering Xinjiang UniversityUrumqi 830046China State Grid Jiangsu Electric Power Research Institute Nanjing 211103China

To investigate impact of time delays on the small signal stability of power systems, the least-damped eigenvalues with the smallest damping ratios have been calculated by eigen-analysis methods based on Solution Operator Discretization (SOD) with Pseudo-Spectral collocation (PS) and Implicit Runge-Kutta (IRK) methods. This paper evolves SOD-PSIIRK into their partial counterparts, i.e., PSOD-PSIIRK, with greatly enhanced efficiency and reliability in analyzing large-scale time delayed power systems. Compared with SOD-PSIIRK, PSOD-PSIIRK are characterized in constructing low order discretization matrices of solution operator as well as efficiently and directly solving the embedded Matrix-Inverse-Vector Products (MIVPs). The dimensions of the discretization matrices of solution operator are largely reduced as only the retarded state variables are discretized, rather than all state variables as in SOD-PSIIRK. Meanwhile, the proposed PSOD-PSIIRK optimize the most computationally expensive operations in SOD-PSIIRK by avoiding the iterative solutions to the two embedded MIVPs. PSOD-PS/IRK directly and efficiently compute the MIVPs via factorizing the Kronecker product-like discretization matrices of the solution operator into Schur complements. The Central China-North China ultra-high-voltage power grid with 80577 state variables serves to validate the proposed PSOD-PSIIRK and shows that compared with SOD-PSIIRK, the computational time consumed by PSOD-PSIIRK is cut down by 49.96 times without loss of any accuracy.

关键词： Eigenvalue analysis low frequency oscillation Schur complement decomposition small signal stability solution operator discretization spectral discretization time delay wide-area measurement system

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Effects of Corona Discharge from the Grounding Tip on Charge Evolution of Wall Bushing

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IEEE Transactions on power Delivery 2025年第3期40卷 1682-1693页

作者： Bai, Zheng Zhou, Yuanxiang Zhang, Yunxiao Huang, Xin Xie, Xiongjie Liu, Taiwei Tsinghua University State Key Laboratory of Power System Operation and Control Department of Electrical Engineering Beijing100084 China Electric Power Research Institute State Key Laboratory of Power Grid Environmental Protection Wuhan430204 China

Manufacturers consider that the grounding tip near the wall bushing flange is a potentially important factor in several sheath perforation accidents. Taking a ±100 kV true type SF6 gas-insulated bushing as a typical wall bushing, this paper tests the impact of the nearby grounding tip on the charge accumulation. Based on the experiment results, we propose the three-dimensional nonlinear conduction model to unravel the charge accumulation process and the three-dimensional corona ion migration model to clarify the corona process. It is concluded that the consumption of gas ions leads to the nonlinear charge relaxation process. When the corona of grounding tip incepts, numerous ions are generated, forming an "overcharge" phenomenon. The electric field at the insulator-sheds interface and the SF6-insulator interface increases compared to the normal condition, with non-uniform distribution along the circumferential direction. Material inhomogeneity amplifies electric field distortion and creates insulation weaknesses, making insulation aging more likely and potentially leading to a slowly developing electrical tree breakdown process. The length of the needle tip affects the duration of the corona effect;an excessively long needle tip can cause a sustained corona discharge. This research provides a foundation for bushing accidents analysis and operation reliability improvement. © 1986-2012 IEEE.

关键词： Bushings

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Two-Stage Scheduling Model for Flexible Resources in Active Distribution Networks Based on Probabilistic Risk Perception

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Energy engineering 2025年第2期122卷 681-707页

作者： Yukai Li Ruixue Zhang Yongfeng Ni Hongkai Qiu Yuning Zhang Chunming Liu Beijing Kedong Power Control System Co. Ltd.State Grid Electric Power Research InstituteBeijing100192China School of Electrical and Electronic Engineering North China Electric Power UniversityBeijing102206China

Aiming at the problems of increasing uncertainty of low-carbon generation energy in active distribution network(ADN)and the difficulty of security assessment of distribution network,this paper proposes a two-phase scheduling model for flexible resources in ADN based on probabilistic risk ***,a full-cycle probabilistic trend sequence is constructed based on the source-load historical data,and in the day-ahead scheduling phase,the response interval of the flexibility resources on the load and storage side is optimized based on the probabilistic trend,with the probability of the security boundary as the security constraint,and with the economy as the *** in the intraday phase,the core security and economic operation boundary of theADNis screened in real ***,it quantitatively senses the degree of threat to the core security and economic operation boundary under the current source-load prediction information,and identifies the strictly secure and low/high-risk time *** resources within the response interval are dynamically adjusted in real-time by focusing on high-risk periods to cope with future core risks of the distribution ***,the improved IEEE 33-node distribution system is simulated to obtain the flexibility resource scheduling scheme on the load and storage *** results are evaluated from the perspectives of risk probability and flexible resource utilization efficiency,and the analysis shows that the scheduling model in this paper can promote the consumption of low-carbon energy from wind and photovoltaic sourceswhile reducing the operational risk of the distribution network.

关键词： Core operation boundary probabilistic power flow risk perception optimize scheduling flexible resource

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Molecular Dynamics Simulation of Key Physical Properties of Polyimide Nanocomposites 19th

Molecular Dynamics Simulation of Key Physical Properties of ...

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19th Annual Conference of China Electrotechnical Society, ACCES 2024

作者： Xu, Yuan Hou, Chengzhi Peng, Tianying Wang, Jian Zhang, Shumin Liu, Jikui State Key Lab of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University Beijing China Beijing Institute of Control Engineering Beijing China

ISBN: (纸本)9789819613861

This article is based on molecular dynamics simulation technology and simulates the effects of different types of POSS doping on key properties such as glass transition temperature and mechanical properties of PI composite materials through the simulation software Materials Studio. The modification mechanism of relative dielectric constant, thermal diffusion coefficient and other characteristics is explained, and the improvement of PI properties before and after modification, as well as the influence of different doping conditions of POSS on the improvement of various properties of PI composite materials, are deeply explored from a microscopic level. The results showed that the thermal, mechanical, and electrical properties of PI were improved after structural modification;After adding POSS, the glass transition temperature and thermal diffusion coefficient of PI composite material are significantly improved, the mechanical properties are significantly enhanced, and the dielectric constant is reduced. Moreover, the modification effect of various properties is most obvious when PI grafted with POSS is used as a dopant. The 9% POSS-PI2/PI2 material has the most outstanding properties and can be used as a new type of PI composite material to suppress the accumulation of charges in spacecraft conductive slip rings. © Beijing Paike Culture Commu. Co., Ltd. 2025.

关键词： Glass Transition Temperature Mechanical Property Molecular Dynamics Simulation Polyimide POSS

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Study on the Surface Flashover Characteristics of Polyimide Under Electron Irradiation 19th

Study on the Surface Flashover Characteristics of Polyimide ...

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19th Annual Conference of China Electrotechnical Society, ACCES 2024

作者： Hou, Chengzhi Xu, Yuan Wang, Juqi Wang, Jian Zhang, Shumin Liu, Jikui State Key Lab of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University Beijing China Beijing Institute of Control Engineering Beijing China

ISBN: (纸本)9789819613861

Polyimide material can handle high temperatures and has good insulation. When spacecraft and satellites work in space, the vacuum dielectric interface is most likely to have electrical discharge. The study looks at how polyimide affects the way electrical discharge happens on a vacuum surface when exposed to an electron beam. The test results show that the voltage needed to cause flashover on the surface of polyimide treated with electron beams is higher than that of untreated polyimide. Also, this flashover voltage gets higher when the energy of the electrons increases. After being hit by electrons, the electric field created by the electrons on the surface of the polyimide layer goes in the opposite direction to the direct current electric field. When electrons have more energy, it increases the amount of charge that gets trapped deep inside. This makes the voltage needed to cause flashover on the surface of the polyimide go up. As the density of the electron beam goes up, the voltage at which polyimide starts to discharge on its surface goes down. This happens because when the beam density gets higher, the combined strength of the electric fields increases, causing surface flashover to occur. © Beijing Paike Culture Commu. Co., Ltd. 2025.

关键词： Electron irradiation

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Preparation and Comprehensive Properties Study of Polyimide Films Modified with SiC and CNT

Preparation and Comprehensive Properties Study of Polyimide ...

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International Conference of Electrical, Electronic and Networked Energy systems, EENES 2024

作者： Peng, Tianying Wang, Juqi Wang, Jian Zhang, Shumin Liu, Jikui State Key Lab of Alternate Electrical Power System With Renewable Energy Sources North China Electric Power University Beijing102206 China Beijing Institute of Control Engineering Beijing100089 China

ISBN: (纸本)9789819618675

In both power systems and aerospace electrical fields, with the increasing application voltage levels of equipment, the use of traditional polyimide (PI) films as insulation materials is prone to corona discharge and even insulation failure, it is difficult to ensure the safe operation of equipment. In order to improve the thermal conductivity and corona resistance of polyimide films, this experiment adopts a synergistic modification of polyimide with carbon nanotubes (CNT) with good conductivity and high mechanical strength, and 10% doped silicon carbide. We investigate and evaluate the properties of modified composite films with different components, and explore the optimal formula for synergistically improving the comprehensive performance of composite films. The experimental results show that (10% SiC + 0.7% CNT)/PI composite films have the best comprehensive properties, and the 5% mass loss temperature is 30 ℃ higher than that of pure PI film, the thermal conductivity and tensile strength of PI film were increased by 95.7% and 22.53%, respectively, and the first long-flow discharge and flashover time were 332 min and 372 min, respectively, which were 672.09% and 500% higher than those of PI film, respectively, the threshold field strength of the nonlinear conductivity is 4.30 MV/m, which is favorable for promoting space charge transport in high field strength. © Beijing Paike Culture Commu. Co., Ltd. 2025.

关键词： Tensile strength

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Mechanism and Methods for Fault Recovery of Grid-Forming Inverter by Graphical Illustration

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IEEE Transactions on power systems 2025年第2期40卷 1973-1976页

作者： Yang, Jialun Ye, Hua Wang, Yantuan Liu, Yutian Li, Yujun Du, Zhengchun Shandong Research Institute of Industrial Technology Jinan250061 China Shandong University Key Laboratory of Power System Intelligent Dispatch and Control Ministry of Education Jinan250061 China Xi'an Jiaotong University Department of Electrical Engineering Xi'an710049 China

The existing priority-based current limiting control (CLC) for grid-forming (GFM) inverters may lead to failures in fault recovery, including being locked in CLC and mode oscillation between CLC and constant voltage control (CVC). To resolve these problems, this letter first reveals the fault recovery mechanism of droop controlled GFM inverters by illustrating the conditions of three fault recovery states in the phasor diagram. Then, two methods including determination of the optimal range of current angle and upper limit of saturation block are presented to guarantee successful fault recovery of GFM inverters. The correctness of theoretical analyses is verified and validated by multiple experimental tests. © 1969-2012 IEEE.

关键词： Fault current limiters

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Multi-Objective Coordination and Stability control of High Proportion Wind power system Based on K-Domain Tuning Damping 19th

Multi-Objective Coordination and Stability Control of High P...

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19th Annual Conference of China Electrotechnical Society, ACCES 2024

作者： Zhang, Qingtao Gao, Diju Zhang, Dan Cai, Haiqing Gu, Haohan Chen, Wei Wu, Wencong Chen, Zhihao Institute of Logistics Engineering Shanghai Maritime University Shanghai China Institute of Logistic Science and Engineering Shanghai Maritime University Shanghai China Guangdong Provincial Key Laboratory of Intelligent Operation and Control for New Energy Power System Guangzhou China State Key Laboratory of HVDC Electric Power Research Institute China Southern Power Grid Guangzhou China National Energy Power Grid Technology R&D Centre Guangzhou China CSG Key Laboratory for Power System Simulation Electric Power Research Institute China Southern Power Grid Guangzhou China

ISBN: (纸本)9789819608966

With the further development of "double high" characteristics of power system, the traditional stability problem dominated by synchronous generator has gradually evolved into a new stability problem dominated by power electronic equipment control. In addition, different types of failure problems can occur in wind power systems. In order to achieve multi-objective coordinated and stable operation of high proportion wind power system, a damping control method with parameters tuning is proposed, which includes the design of filtering link and proportional amplification link. Among them, the key parameters of the proportional link are adjusted. Finally, the feasibility of the proposed control method is verified by simulation tests. © Beijing Paike Culture Commu. Co., Ltd. 2025.

关键词： Electric power system stability

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Numerical Simulation of Streamer Discharge in Transformer Oil Under Various Ionization Energies 19th

Numerical Simulation of Streamer Discharge in Transformer Oi...

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19th Annual Conference of China Electrotechnical Society, ACCES 2024

作者： Bao, Yanyan Liang, Shaobin Wang, Feng Zhang, Guangdong Chen, Jianning Zhou, Yuanxiang State Grid Gansu Electric Power Research Institute Lanzhou730070 China State Key Laboratory of Power System Operation and Control Beijing100084 China Department of Electrical Engineering Tsinghua University Beijing100084 China

ISBN: (纸本)9789819613786

Discharge in transformer oil is one of the primary causes of transformer failures. The physical mechanisms of oil discharges are not yet fully understood. Scholars have simulated the discharge process with electrodynamics model, but there is limited research on how the ionization energy, which changes due to various factors such as components and temperature of transformer oil, affect the streamer discharge characteristic. To improve the mechanism of discharge in transformer oil, this paper adopts an electrohydrodynamic model to study the impact of different ionization energies on the streamer discharge characteristics of transformer oil, including initiation voltage, discharge voltage, development speed, and electric field strength. When the ionization energy is between 6.1 eV and 8.1 eV, the initiation voltage and discharge voltage increase linearly with the ionization energy. Within the range of 7.1 eV to 8.1 eV, the time in the streamer accumulation phase increases exponentially with the ionization energy, while the streamer development speed decreases. © Beijing Paike Culture Commu. Co., Ltd. 2025.

关键词： Electrohydrodynamics

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