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Thermofluidic investigations of oil natural transformer:Closed-loop modelling and experimental validation

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High Voltage 2024年第1期9卷 230-240页

作者： Yuan Li Yiran Gao Chen Wang Chao Zhu Ying Li Yuankai Wang Guanjun Zhang State Key Laboratory of Electrical Insulation and Power Equipment Xi'an Jiaotong UniversityXi'anChina Electric Power Research Institute of State grid Shaanxi Electric Power Co. Ltd.Xi'anChina TBEA Hengyang Transformer Co. Ltd.HengyangChina

Excessively high temperatures inside a power transformer can accelerate the ageing rate and even cause unplanned *** estimating the hot-spot temperature(HST)of a power transformer is important for regulating the load and ensuring long-term *** this study,a closed-loop model of a 110-kV product transformer with an oil natural/air forced(ONAF)cooling mode is built to predict HST,in which the compression ratio of windings,equivalent heat source and radiator geometry are *** to the flow field of the winding,the‘dead oil zone’and reverse oil flow are observed in the horizontal oil *** accuracy of the proposed model is experimentally validated by temperature-rise *** results show that the absolute errors between the measured results and simulation are below 5°C,and the average error is~2°***,the arrangements of windings and radiators are studied to enhance the oil *** adding 5 washers to the high-voltage winding,the average temperature can be decreased by 6°C compared with the case without a *** the radiator can also mitigate the characteristic temperatures,and the optimal height difference between the radiator and winding centre is suggested to be 0.66 m.

关键词： winding arrangement adding

Regulated reaction pathway of CO2 photoreduction into CH4 by metal atom pair sites

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Rare Metals 2024年第9期43卷 4620-4627页

作者： Dong-Po He Guang-Bing Huang Jun Hu Yang Wu Xiao-Dong Li Qing-Xia Chen Shan Zhu Wen-Sheng Yan Jun-Fa Zhu Yang Pan Xing-Chen Jiao Key Laboratory of Synthetic and Biological Colloids Ministry of EducationSchool of Chemical and Material EngineeringJiangnan University Hefei National Research Center for Physical Sciences at Microscale National Synchrotron Radiation LaboratoryUniversity of Science and Technology of China Max Planck Institute of Microstructure Physics State grid Anhui Electric Power Research Institute

The carbon dioxide （CO2） reduction process involves complex protonation, making the resulting product often unpredictable. To achieve the desired product, it is crucial to manipulate the reaction steps. Herein, we build the metal atom pair sites for selective CO2photoreduction into methane. As a prototype, Ni atom pair sites loaded on the Mo S2nanosheets were synthesized and verified by highresolution transmission electron microscopy （HRTEM）,X-ray photoelectron spectroscopy （XPS） and X-rayabsorption near edge structure spectra （XANES）. In-situ Fourier transform infrared spectroscopy （FTIR） monitors the*CHO group, a crucial intermediate in CH4production,during CO2photoreduction on the Ni-Mo S2nanosheets,whereas this monitoring is not observed for the Mo S2nanosheets. Also, theoretical calculations disclose that over the Ni-Mo S2nanosheet slab, the formation energy of*CHO intermediates is determined to be lower （0.585 e V） than the desorption energy of*CO intermediates for CO production（0.64 e V）, implying the higher selectivity of CH4production. Accordingly, the Ni-Mo S2nanosheets demonstrate a methane formation rate of 27.21μmol·g-1·h-1, coupled with an impressive electron selectivity of 94.2%.

关键词： Nanosheets

Arc Grounding Fault Identification Using Integrated Characteristics in the Power grid

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Energy Engineering 2024年第7期121卷 1883-1901页

作者： Penghui Liu Yaning Zhang Yuxing Dai Yanzhou Sun School of Electrical Engineering and automation Henan Polytechnic UniversityJiaozuo454003China Research and Development Center Guangdong Zhicheng Champion Group Co.Ltd.Dongguan523000China Henan Key Laboratory of Intelligent Detection and Control of Coal Mine Equipment Henan Polytechnic UniversityJiaozuo454003China

Arc grounding faults occur frequently in the power grid with small resistance grounding neutral *** existing arc fault identification technology only uses the fault line signal characteristics to set the identification index,which leads to detection failure when the arc zero-off characteristic is *** solve this problem,this paper presents an arc fault identification method by utilizing integrated signal characteristics of both the fault line and sound ***,the waveform characteristics of the fault line and sound lines under an arc grounding fault are *** that,the convex hull,gradient product,and correlation coefficient index are used as the basic characteristic parameters to establish fault identification ***,the logistic regression algorithm is employed to deal with the reference samples,establish the machine discrimination model,and realize the discrimination of fault ***,simulation test results and experimental results verify the accuracy of the proposed *** comparison analysis shows that the proposed method has higher recognition accuracy,especially when the arc dissipation power is smaller than 2×10^(3) W,the zero-off period is not *** conclusion,the proposed method expands the arc fault identification theory.

关键词： Arc fault convex hull algorithm correlation coefficient fault identification gradient logistic regression

An Intelligent Coordinated Protection and Control Strategy for Distribution Network with Wind Generation Integration

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CSEE Journal of Power and Energy Systems 2016年第4期2卷 23-30页

作者： Zhou Liu Hans Kr.Høidalen Murari Mohan Saha Electrical Power Engineering Department Norwegian University of Science and Technology(NTNU)TrondheimNO 7491Norway grid automation product ABB AB72244Vasteras Sweden

Integration of distributed generation(DG)can change the fault current level and direction in the distribution system,which affects the related protection *** order to limit the negative impact of DG integration and upgrade the protection system performance,an intelligent coordinated protection and control strategy is proposed.A cost based optimization method is adopted to minimize the operation costs of possible *** aim is to define the optimal relay settings for the present operation condition,and the most suitable control mode of converter based wind turbine *** studies on a hardware in the loop real time simulation platform demonstrate the proposed protection strategy.

关键词： Converter based wind turbine DG coordinated protection and control hardware in the loop real time simulation

Ripple-based matrix modeling and cross-coupling effect analysis of double-input DC-DC Boost converters

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Science China(Technological Sciences) 2022年第8期65卷 1878-1890页

作者： ZHANG Hao REN Han YI ChuanZhi DONG DaChu State Key Lab of Electrical Insulation&Power Equipment School of Electrical EngineeringXi’an Jiaotong UniversityXi’an 710049China Bosch Automotive product(Suzhou)Co.Ltd Suzhou 215000China Hangzhou Power Supply Company of State grid Zhejiang Electric Power Co.Ltd Hangzhou 310000China

This paper deals with the modeling and cross-coupling effect analysis in double-input Boost converters with multiplex current control. A ripple-based multiplex current controlled matrix model is proposed to restore the system's high-frequency domain dynamics information and resolve the coexistence problem of the sample-and-hold effect in multiplex current controllers, which significantly improves the resolution of the conventional average model. Based on the proposed model, both sub-harmonic and low-frequency oscillations are identified in terms of stability analysis, and the inherent mechanism of these complicated nonlinear dynamic behavior is revealed, which not only illustrates the origin of the oscillations but also points out the dominant factors in diverse types of instability situation. Besides, cross-coupling effect analysis is performed to study the interaction between the input ports with the help of the Gershgorin band, and the mechanism of the special unbalanced oscillation phenomenon is revealed. Furthermore, the sensitivity analysis approach is used to identify the key parameters with respect to the cross-coupling effect, which provides more design-oriented knowledge for practical engineering. In addition, the benefits of the proposed model are further illustrated through a comparative analysis. Finally, these theoretical results are verified by experimental ones. These results are beneficial to the improvement of performance as well as the understanding of the cross-coupling effect of multi-input converters.

关键词： ripple-based matrix model cross-coupling effect multiplex current control multi-input converter Gershgorin band

Towards a standardisation for digital inputs and outputs of protection functions in IEC 60255 series

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Protection and Control of Modern Power Systems 2022年第1期7卷 382-392页

作者： Volker Leitloff Hao Chen Dehui Chen Andrea Bonetti Lei Xu Ahmed Mohamed Carl Byman French Transmission Network Operator Rte ParisFrance State grid Jiangsu Electric Power Co. Ltd.NanjingChina State grid Electric Power Institute NanjingChina Royal Institute of Technology StockholmSweden NR Elec-tric Co. Ltd.NanjingChina Scottish and Southern Energy Network(SSEN) GlasgowUK Hitachi Energy VästeråsSweden.

Fully digitalized substations using IEC 61850 process bus are being introduced all over the *** utilities have featured pilot projects,demonstrators or even industrial scale deployment of these Fully Digital Protection,Auto-mation and Control Systems(FD-PACS).product standards such as profiles for Instrument Transformers have been developed and published(IEC 61869-6 and IEC 61869-9 by TC 38-Instrument Transformers).This raises the question about the standards for digitally interfaced protection *** 2016,IEC TC 95(Measuring relays and protection equipment)charged a working group to investigate this subject and to elaborate recommendations concerning requirements and testing of protection IED with digital inputs and outputs for protection standards(IEC 60255-1xx series).For protection functions,publisher/subscriber based data streams are supposed to comply with IEC 61850 and IEC 61869 *** holds in particular for Sampled Values(SV)representing energising inputs of the protection function,and is also applicable to Generic Object Oriented Substation Event(GOOSE)which can be used for input or output of protection *** attributes of published data depend on the operational and connection status of the function and the hosting *** addition,protection functions have to take into account the information regarding the time synchronisation of the received SV and other *** paper gives an overview of these features and the proposed way to take them into account in the IEC 60255 standard *** describes the progress of WG 2 and relates it to existing standardization documents.

关键词： Process bus Protection function Digital interface SAMU LPIT Standards IEC 61850

Performance Analysis of Corroded Grounding Devices with an Accurate Corrosion Model

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CSEE Journal of Power and Energy Systems 2023年第3期9卷 1235-1247页

作者： Yihua Dan Zhanlong Zhang Pengfei Gan Huarui Ye Qiaoyi Li Jun Deng State Key Laboratory of Power Transmission Equipment&System Security and New Technology Chongqing UniversityChongqing 400030China Test Centre of EHV Transmission Company China Southern Power GridGuangzhou 510663China

Grounding devices are significant to the operation of the power transmission line and power *** soil and leakage current can easily cause the corrosion of carbon steel grounding devices,resulting in power ***,most carbon steel grounding devices in service are already corroded,and the accurate calculation of grounding parameters for corroded grounding devices is ***,most existing methods for calculating the grounding parameters of corroded grounding devices usually have the following disadvantages:1)They only consider whether the grounding devices are broken or not,and cannot analyze the grounding parameters of grounding devices with different corrosion degrees;2)They assume that the corroded grounding device is a conductor with a smaller diameter,and ignore the impact of the corrosion product layer,resulting in calculation *** solve the above problems,this paper establishes an accurate corrosion model for grounding devices based on the volume expansion coefficient of corrosion *** grounding parameters calculation method for corroded grounding devices is proposed based on the boundary element method(BEM)and Galerkin’s *** the grounding performance of tower grounding grids with different corrosion degrees in different soils(uniform and layered)is ***,some features of grounding parameters of corroded grounding devices are *** study can accurately calculate the grounding parameters of the corroded grounding devices and has far-reaching engineering significance for the safety of power equipment.

关键词： Corroded grounding devices corrosion product layer grounding parameters volume expansion coefficient

Government Subsidy’s Effect on the Channel Strategies of Energy-Saving Supply Chain

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Journal of Systems Science and Systems Engineering 2023年第6期32卷 729-770页

作者： Zijian Bi Xiaohui Yu Qiang Zhang Zihan Su State grid Jibei Electric Power Co. LtdTangshan063000China Institute for Carbon Peak and Neutrality&Logistics School Beijing101149China School of Management&Economics Beijing Institute of TechnologyBeijing100081China

As subsidy is a popular form of stimulating consumption,not only for home appliances market,the effectiveness of selling promotion subsidies need to be *** this paper,we check the role of promotion subsidies in the offline channel layout by establishing three models,i.e.,no subsidy,customer rebate and retailer *** kinds of online-to-offline strategies are considered,which are retailer’s opening separate and sharing offline *** is gotten that:both customer rebate and retailer subsidy increase the possibility of opening offline channels by sharing offline store strategy,but customer rebate takes high price than no subsidy while retailer subsidy is on the *** the growing subsidy,both customer rebate and retailer subsidy could make offline channels opened by separate or sharing offline store strategy,but the customer rebate brings more *** customer rebate and retailer subsidy require less social welfare to open offline channel,but the customer rebate brings more consumer surplus of opening offline channels than retailer subsidy for a given market ***,government should give the subsidy to customer,not to retailer,even if it brings the increasing of product’price.

关键词： Biform game online-to-offline strategies social welfare service

AES RSA-SM2 Algorithm against Man-in-the-Middle Attack in IEC 60870-5-104 Protocol

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Journal of Computer and Communications 2022年第1期10卷 27-41页

作者： Shan Shi Yong Wang Cunming Zou Yingjie Tian College of Computer Science and Technology Shanghai University of Electric Shanghai China Third Institute of Ministry of Public Security National Network and Information System Safety Product Quality Supervision and Testing Center Shanghai China Institute of Electric Power Science State Grid Shanghai Electric Power Company Shanghai China

The IEC60870-5-104 protocol lacks an integrated authentication mechanism during plaintext transmission, and is vulnerable to security threats, monitoring, tampering, or cutting off communication connections. In order to verify the security problems of 104 protocol, the 104 master-slave communication implemented DoS attacks, ARP spoofing and Ettercap packet filtering and other man-in-the-middle attacks. DoS attacks may damage the network functions of the 104 communication host, resulting in communication interruption. ARP spoofing damaged the data privacy of the 104 protocol, and Ettercap packet filtering cut off the communication connection between the master and the slave. In order to resist the man-in-the-middle attack, the AES and RSA hybrid encryption signature algorithm and the national secret SM2 elliptic curve algorithm are proposed. AES and RSA hybrid encryption increases the security strength of communication data and realizes identity authentication. The digital signature implemented by the SM2 algorithm can realize identity verification, ensure that the data has not been tampered with, and can ensure the integrity of the data. Both of them improve the communication security of the 104 protocol.

关键词： 104 Protocol Man in the Middle Attack AES and RSA Hybrid Encryption Signature National Secret SM2 Algorithm