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High Voltage 2024年第3期9卷 659-673页

作者： Tianrun Qi Hanwen Ren Haoyu Gao Qingmin Li Yidan Ma Yiqun Ma Tao Xiao state key laboratory of alternate Electrical power system with renewable energy sources North China Electric Power UniversityBeijingChina

For the space charge measurement method with optical excitation for electrical insulation,the distortion of the excitation laser on the measurement signal and the accumulation of space charge have not been discussed *** experiment and simulation results show that three types of distorted components introduced by optical excitation can lead to distortion of the upper interface ***,the factors causing distortion of the measured signal and the formation mechanism are analysed.A virtual electrode potential compensation method and a distorted component extraction method are ***,an attenuation restoration and charge conversion correction factor is intro-duced,leading to a novel signal processing algorithm adapted to space charge optical measurement *** with the traditional algorithm,the novel algorithm has an error of less than 1%in the calculation of charge and electric field strength,with an increase in accuracy of 47.7%and 9.81%,*** applying the novel restoration algorithm,the comparison shows that the space charge accumulation does not change significantly under laser irradiation,verifying the reliability of the optical *** given algorithm can provide a theoretical and technical foundation for the realisation of the optical measurement method for space charge.

关键词： charge algorithm excitation

Framework for Preventive Control of power systems to Defend Against Extreme Events

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CSEE Journal of power and energy systems 2024年第2期10卷 856-870页

作者： Yuwei Xiang Tong Wang Zengping Wang state key laboratory of alternate Electrical power system with renewable energy sources North China Electric Power UniversityBeijing 102206China

Enhancing power system resilience against extreme events is becoming increasingly critical. This paper discusses a unified framework for preventive control of power systems to enhance system resilience, which includes three parts: resilience assessment, resilience grading, and resilience enhancement. First, the resilience assessment contains facility-level and system-level resilience assessment. The concept of fragility curve is used in the facility-level resilience assessment. Various resilience indices are developed in system-level resilience assessment to roundly depict the impacts of extreme events on power systems and determine the system resilience. On this basis, the resilience is divided into different levels by resilience grading strategy, which can efficiently quantify the severity of the impact of extreme events and provide decision-making for the resilience enhancement strategies. Then, control strategies for enhancing power system resilience are also divided according to different resilience levels. A controlled islanding based preventive control is proposed to enhance system resilience, which aims to strengthen the first defensive line of power systems to deal with extreme events. Finally, taking the typhoon disaster in extreme events as an example, two tests carried out with two typhoons demonstrate the efficiency of the proposed method.

关键词： Controlled islanding extreme events power system resilience preventive control

Micro-mechanism Study on the Different Antioxidants Protective Effect of Vegetable Oil by ReaxFF Molecular Dynamics

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CSEE Journal of power and energy systems 2024年第3期10卷 1269-1279页

作者： Haoxi Cong Xuefeng Hu Hao Pan Qingmin Li state key laboratory of alternate Electrical power system With renewable energy sources North China Electric Power UniversityBeijing 102206China

The aging problem of vegetable oil has severely restricted the popularization and application of vegetable oil *** antioxidants is the most recommended *** present,there is insufficient research on the micromechanism application of the protective effect of antioxidants on vegetable *** this paper,multiple vegetable oil models with different types and concentrations of antioxidants are *** the molecular dynamics simulation based on ReaxFF is carried out at different temperatures and oxygen *** show that the protective mechanism of antioxidants is to release H and combine this with free radicals generated by the decomposition of unsaturated fatty acids(UFA)in the *** addition,the protective effects of four antioxidants show different *** stronger ones are tert-butyl hydroquinone(TBHQ)and butylated hydroxytoluene(BHT),while the weaker ones are butylated hydroxyanisole(BHA)and propyl gallate(PG).TBHQ has a better protective effect at lower concentrations,but the decomposition of UFA is promoted at higher *** the temperature rises,the decomposition of UFA is *** the addition of oxygen,smaller molecular compounds are easily oxidized,and the decomposition of UFA is *** above research could reveal the microscopic mechanism of antioxidant protection on vegetable oil,providing theoretical references for further exploration of effective vegetable oil aging protection technology.

关键词： Antioxidant molecular dynamics transformer vegetable oil

Metal-free Optical Pressure Sensor with High Sensitivity and Extensive Range

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CSEE Journal of power and energy systems 2024年第3期10卷 1291-1300页

作者： Mao Ji Meng Huang Haomin Lyu Sheng Shi Bo Qi Chengrong Li state key laboratory of alternate Electrical power system with renewable energy sources North China Electric Power UniversityBeijing 102206China IEEE CSEE

Pressure monitoring of a transformer oil tank can grasp the pressure change process caused by gas production when severe internal defects occur and take timely measures to ensure the safe operation of the *** pressure sensors generally use metal encapsulation or have an air cavity structure,threatening the transformer’s insulation if it is directly used inside the *** this end,this paper proposes a method for developing a high-sensitivity,large-range,and metallizationfree optical pressure sensing device with temperature *** grating is encapsulated by fluorosilicone rubber and supplemented by an epoxy resin shielding shell on the *** the same time,a double-grating vertical arrangement is adopted to improve pressure measurement sensitivity,further avoiding the influence of temperature rise caused by a defect of the transformer on the measurement result of the *** addition,by optimizing the geometric structure of the internal sensitizing element,pre-stretching length of the fiber grating,gap distance,and other parameters,probe size can be reduced while ensuring the sensor’s *** show the proposed method can meet the requirements of sensor fabrication with different sensitivities and ranges,and to a certain extent,both high sensitivity and extensive ranges can be taken into *** sensitivity of the fabricated prototype is 15 pm/kPa,and the range is about 0.2 *** the same time,the metal-free feature of the sensor makes it suitable for use in various oil-immersed power *** records oil pressure changes caused by oil discharge breakdown,making it sensitive to small pressure changes in early failures.

关键词： Highly sensitive extensive range optical sensing no metallization pressure perception temperature compensation transformer

Crystallization management of CsPbI_(2)Br perovskites by PbAc_(2)-incorporated twice spin-coating process for efficient and stable CsPbI_(2)Br perovskite solar cells

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Journal of energy Chemistry 2024年第10期97卷 419-428,I0008页

作者： Yu Liu Kun Lang Huifang Han Huijing Liu Yao Fu Pengchen Zou Yinhui Lyu Jia Xu Jianxi Yao state key laboratory of alternate Electrical power system with renewable energy sources Beijing Key Laboratory of Energy Safety and Clean UtilizationNorth China Electric Power UniversityBeijing 102206China

CsPbI_(2)Br perovskite solar cell has been extensively studied due to its exceptional thermal stability and relatively stable perovskite phase ***,the presence of bromine leads to a rapid crystallization rate of CsPbI_(2)Br films,resulting in small grain size and high defect ***,CsPbI_(2)Br demonstrates poor light absorption due to its wide ***,it is crucial to control the crystallization rate and increase the film thickness to reduce defect density,enhance light absorption,and improve photovoltaic *** this study,we utilized a PbAc_(2)-incorporated twice spincoating(PTS) process to address these ***,PbAc_(2) was added to the CsPbI_(2)Br precursor solution to form a CsPbI_(2)Br film,which was then coated with the CsPbI_(2)Br precursor solution to produce the PTS film,Ac^(-)can delay the perovskite crystallization,leading to the formation of thicker and denser CsPbI_(2)Br ***,lone-pair electrons of the oxygen atom provided by Ac^(-)formed coordination bonds with under-coordinated Pb~(2+) ions to fill halogen ion vacancies,thereby reducing the defect ***,the PTS CsPbI_(2)Br device achieved a peak power conversion efficiency(PCE) of 16.19% and maintained 96.7% of its initial PCE over 1500 h at room temperature under 25% relative humidity without any encapsulation.

关键词： CsPbI_(2)Br Twice spin-coating process PbAc_(2) Crystallization management Perovskite solar cells

A spatiotemporal evolution model of a short-circuit arc to a secondary arc based on the improved charge simulation method

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Plasma Science and Technology 2024年第1期26卷 62-73页

作者：丛浩熹王宇轩乔力盼苏文晶李庆民 state key laboratory of alternate Electrical power system with renewable energy sources North China Electric Power UniversityBeijing 102206People’s Republic of China

The initial shape of the secondary arc considerably influences its subsequent *** establish the model for the arcing time of the secondary arc and modify the single-phase reclosing sequence,theoretical and experimental analysis of the evolution process of the short-circuit arc to the secondary arc is *** this study,an improved charge simulation method was used to develop the internal-space electric-field model of the short-circuit *** intensity of the electric field was used as an independent variable to describe the initial shape of the secondary arc.A secondary arc evolution model was developed based on this ***,the accuracy of the model was evaluated by comparison with physical experimental *** the secondary arc current increased,the arcing time and dispersion *** is an overall trend of increasing arc length with increasing arcing ***,there is a reduction in arc length during arc ignition due to short circuits between the arc ***,the arcing time decreased in the range of 0°-90°as the angle between the wind direction and the x-axis *** work investigated the method by which short-circuit arcs evolve into secondary *** results can be used to develop the secondary arc evolution model and to provide both a technical and theoretical basis for secondary arc suppression.

关键词： short-circuit arc secondary arc stochasticity improved charge simulation method arc time

Insulation Design Rule for a Spacer in SF_(6)/N_(2)-filled DC Gas Insulated Apparatus

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CSEE Journal of power and energy systems 2024年第2期10卷 727-735页

作者： Hongyang Zhou Guoming Ma Meng Zhang Cong Wang Youping Tu Chengrong Li state key laboratory of alternate Electrical power system with renewable energy sources and the Beijing key laboratory of High Voltage and EMC North China Electric Power UniversityBeijing 102206China

A recurring challenge of a DC SF_(6)/N_(2)-filled GIS/GIL apparatus is the charge accumulation at DC *** conventional design rules and knowledge of AC spacers may not be applicable for this new type of apparatus.A novel design rule is proposed considering the effect of accumulated charge on the threshold of electric field strength being resistant to the superposed voltage.A surface charge accumulation simulation model is introduced,and the key parameters in the simulation model are *** addition,an experimental platform for a 100 kV spacer flashover test is *** flashover tests under superimposed voltage with opposing polarities are carried out,and the withstanding voltage of the spacer is ***,based on the proposed model,the threshold of the surface electric field strength(tangential component)on the DC spacer in SF_(6)/N_(2) mixed gases is *** a reliable insulation design of a DC GIS/GIL apparatus filled with 0.7 MPa SF_(6)/N_(2),the threshold of surface electric field strength on the DC spacer is 12 kV/*** insulation design rule can be referenced in the design of a high-voltage DC SF_(6)/N_(2)-filled GIS/GIL apparatus.

关键词： Charge accumulation DC spacer flashover voltage SF_(6)/N_(2) threshold of surface electric field strength

Assessment and Enhancement of FRC of power systems Considering Thermal power Dynamic Conditions

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CSEE Journal of power and energy systems 2024年第4期10卷 1371-1383页

作者： Feng Hong Yalei Pang Weiming Ji Lu Liang Fang Fang Junhong Hao Jizhen Liu state key laboratory of alternate Electric power system with renewable energy sources and School of Control and Computer Engineering North China Electric Power UniversityBeijing 102206China state key laboratory of alternate Electric power system with renewable energy sources School of Energy Power and Mechanical EngineeringNorth China Electric Power UniversityBeijing 102206China

Frequency stability and security have been a vital challenge as large-scale renewable energy is integrated into power *** contrast,the proportion of traditional thermal power units decreases during the decarbonization transformation process,resulting in poor frequency *** paper aims to explore the potential of frequency regulation support,dynamic assessment,and capacity promotion of thermal power plants in the transition *** the dynamic characteristics of the main steam working fluid under different working conditions,a nonlinear observer is constructed by extracting the main steam pressure and valve opening degree *** real-time frequency modulation capacity of thermal power units can provide a dynamic state for the power grid.A dynamic adaptive modification for primary frequency control(PFC)of power systems,including wind power and thermal power,is proposed and *** power dynamic allocation factor is adaptively optimized by predicting the speed droop ratio,and the frequency modulation capability of the system is improved by more than 11%under extreme ***,through the Monte Carlo simulation of unit states of the system under various working conditions,the promotion of the frequency regulation capacity with high wind power penetration(WPP)is verified.

关键词： Dynamic evaluation frequency regulation power system predictive modeling wind penetration

Charge Accumulation Characteristics of SF6-Epoxy Interface Under Negative Repetitive Nanosecond Pulses

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CSEE Journal of power and energy systems 2024年第4期10卷 1808-1815页

作者： Shaocong Wu Geng Chen Yuming Shao Hao Xu Xuanning Zhang Yanyu Liang Youping Tu state key laboratory of alternate Electrical power system with renewable energy sources and the Beijing key laboratory of High Voltage and EMC North China Electric Power UniversityBeijing 102206China

Repetitve nanosecond impulses in gas-insulated metal-enclosed switchgear (GIS) are likely to trigger inside flashover. Interface charges on the spacer in GIS are considered one of the main factors damaging insulation performance and may be induced by overvoltage. For good understanding of insulation failures, accumulation characteristics of charges between SF6 and epoxy spacers under repetitive nanosecond impulses are investigated. It can be found under nanosecond impulses, the charge source in gas volume contributes to interface charge accumulation predominantly. Interface charges will be promoted by impulse number and amplitude. Accumulation processes are analyzed based on runaway electrons mechanism. When impulse amplitude exceeds a threshold value, discharge in the gas volume turns to a runaway mode. A runaway electron leads to the interface charge accumulation. Affected by motion of the runaway electrons, the potential peak gradually moves close to the grounded electrode when impulse amplitude is raised. Meanwhile, increasing impulse number can enhance surface potential. Surface potential will reach saturation eventually. However, memory effect of the repetitive impulse discharge makes the half-peak width of the surface potential at the interface change little. Design of GIS gas-solid insulations can refer to this research.

关键词： GIS interface charge repetitive nano-second pulse SF6

Finite Element Method for Transient Electric Field by Using Indirect Laplace Transform with High Accuracy

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CSEE Journal of power and energy systems 2024年第1期10卷 401-411页

作者： Teng Wen Xiang Cui Xuebao Li Sijia Liu Zhibin Zhao state key laboratory of alternate Electrical power system with renewable energy sources North China Electric Power UniversityBeijing 102206China China Electric power Planning&Engineering Institute Beijing 100120China

This paper focuses on the finite element method in the complex frequency domain(CFD-FEM)for the transient electric ***,the initial value and boundary value problem of the transient electric field under the electroquasistatic field in the complex frequency domain is *** addition,the finite element equation and the constrained electric field equation on the boundary are ***,the indirect algorithm of the numerical inverse Laplace transform is *** on it,the calculation procedures of the CFD-FEM are illustrated in ***,the step response,zero-state response under the positive periodic square waveform(PPSW)voltage,and the zero-input response by the CFD-FEM with direct algorithm and indirect algorithm are ***,the reason for the numerical oscillations of the zero-state response under the PPSW voltage is analyzed,and the method to reduce oscillations is *** results show that the numerical accuracy of the indirect algorithm of the CFD-FEM is more than an order of magnitude higher than that of the direct algorithm when calculating the step response of the transient electric *** proposed method can significantly reduce the numerical oscillations of the zero-state response under the PPSW *** proposed method is helpful for the calculation of the transient electric field,especially in the case of frequency-dependent parameters.

关键词： Electroquasistatic field transient electric field finite element method complex frequency domain numerical Laplace transform