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Experimental study on ice monitoring method for 10 kV transmission line with tangent tower in alpine landform

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High Voltage 2024年第1期9卷 182-194页

作者： Lin Yang Zhiqiang Chen Yanpeng Hao Xinhao Lin Lei Yu Yue Li Zhiyong Yuan Licheng Li School of Electric power South China University of TechnologyGuangzhouChina electrical power Research Institute China Southern Power GridGuangzhouChina Electric power Research Institute of Guizhou power Grid Co.Ltd. GuizhouChina

Ice monitoring methods were applied for 110 kV and above transmission lines with tangent ***,the change in the vertical span is not considered,and a significant difference lies in the tower-conductor structure of 10 kV transmission *** this reason,a proposal is made about the ice monitoring method for the 10 kV transmission line with tangent tower in alpine landform,which includes the ice monitoring system based on pressure measurement and corresponding equivalent ice thickness calculating *** methods calculate the vertical span under different height difference coefficients.A finite element simulation model and a simulated ice load experiment system are established based on real conductors and *** and simulations under four simulated terrains are conducted within 2.5–20 mm ice thickness *** comparison is made between this method and the method without considering the change in vertical *** results show that the two methods are consistent and the relative errors are lower than�4%in simulation and�10%in experiment when the height difference coefficient is *** it is not 0,the relative errors of this method fall between t0.38%and t6.78%in simulation and−6.40%to t6.60%in experiment,while the relative errors of the method without considering the change in vertical span ranges between−11.13%and−20.23%in simulation and−11.65%to−23.20%in experiment.

关键词： methods tangent method

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

Stress Concentration Effect in Interface Between Conductor and Epoxy Resin in Coaxial Components of power Equipment

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CSEE Journal of power and Energy Systems 2024年第1期10卷 412-420页

作者： Chuang Wang Kang Lei Qing Sun Hui Li Jiawei Zhang Lang Zhao Zongren Peng School of electrical Engineering Xi’an University of TechnologyXi’an 710054China Xi’an power Supply Company State Grid Shaanxi Electric Power CompanyXi’an 710032China State Key Laboratory of electrical Insulation and power Equipment Xi’an Jiaotong UniversityXi’an 710049China

The spacer used in gas insulated switchgear(GIS)plays a vital role in its safe *** mismatch of mechanical properties between conductor and insulating material in spacers results in stress concentration at the interface between *** a hydrostatic test,mechanical damages are often initiated from the *** this paper,the stress between aluminum conductors and epoxy resin is studied by using a simplified coaxial structure *** measurement system and finite element simulation are used to explore the generation of stress and strain during curing and *** real-time measurement of strain at the interface shows that the residual strain in the entire process is primarily generated during the cooling ***,the temperature and stress/strain distribution at the interface during the cooling stage are further studied,and combined with experiments and *** consistency between the finite element simulation and the experimental measurement results verifies the validity of the simulation method *** results show that the maximum of the first principal stress generated during the cooling stage of the production process is concentrated on the upper and lower edges of the interface which is critical to the impact of the production quality of the spacer.

关键词： Epoxy resin GIS interface stress/strain distribution

Transient Stability Analysis and Design of VSGs with Different DC-Link Voltage Controllers

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CSEE Journal of power and Energy Systems 2024年第2期10卷 593-604页

作者： Chao Shen Wei Gu Wanxing Sheng Keyan Liu School of electrical Engineering Southeast UniversityNanjingChina power Distribution Research Department China Electric Power Research InstituteBeijing 100192China

Virtual synchronous control has been widely studied for the advantages of emulating inertia for voltage source converters (VSCs). A constant dc-link voltage is usually assumed in existing literature to estimate transient stability of virtual synchronous generators (VSGs). However, actual power supply in the dc-side of VSGs is limited and different dc-link voltage controllers are needed to achieve power balance between DC side and AC side. Addition of dc-link voltage controller has great influence on transient behavior of VSGs, which has not been investigated by previous research. To fill this gap, this paper gives insights into the effect of dc-link voltage dynamics on transient stability of VSGs. First, two typical kinds of VSGs with dc-link voltage controllers are introduced. Then, mathematical models considering dc-link dynamics are established and the effect of dc-link voltage controllers on transient synchronization stability of VSGs is revealed through equal area criterion (EAC). It is found that dc-link voltage controller would reduce stability margin of VSGs and design-oriented transient stability analysis is carried out quantitively using critical clearing time (CCT). Finally, simulation results are given to validate correctness of theoretical analysis.

关键词： DC-link voltage dynamics equal area criterion(eac) transient synchronization stability virtual synchronous generator(VSG)

Improving IEC thermal model for oil natural air natural transformers using optimised parameters based on dynamic simulation

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High Voltage 2024年第1期9卷 217-229页

作者： Lijing Zhang Yingting Luo Gehao Sheng Zizhan Ni Xiuchen Jiang Department of electrical Engineering Shanghai Jiao Tong UniversityShanghaiChina Electric power Research Institute of Guangdong power Grid Corporation GuangzhouChina

Accurate assessment of hot-spot temperature is essential for the safe operation of power *** dynamic thermal models cannot estimate hot-spot temperature accurately since some input parameters are roughly determined by transformer capacity and cooling mode while ignoring the effect of winding structure,tank dimensions,and material physical *** improve the accuracy of temperature assessment,empirical parameters of the IEC thermal model including thermal constants,winding and oil exponents are optimised with the help of numerical simulation in this *** on energy conservation and heat transfer theory,a computational fluid dynamic(CFD)model of a transformer in oil natural air natural(ONAN)cooling mode is *** CFD model simulates the entity's structure,sizes,and multi-stage heat dissipation processes realistically,so it can more precisely calculate the dynamic hot-spot *** to the simulated temperature curves at different operating conditions,the thermal constants and oil exponent are estimated using non-linear regression,and the winding exponent is optimised using linear regression.A case study is conducted on an ONAN *** shows the improved IEC model with optimised parameters can more accurately evaluate hot-spot temperature,and the absolute error is decreased by 2.4 K(38.7%)compared with traditional thermal models.

关键词： temperature properties. thermal

Decision Aid Model for Private-owned Electric Vehicles Participating in Frequency Regulation Ancillary Service Market

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Journal of Modern power Systems and Clean Energy 2024年第2期12卷 621-629页

作者： Liwei Wang Yingyun Sun Haotian Wang Pengfei Zhao Muhammad Safwan Jaffar School of electrical and Electronic Engineering North China Electric Power UniversityBeijing 102206China

To reduce the difficulty and enhance the enthusiasm of private-owned electric vehicles(EVs) in participating in frequency regulation ancillary service market(FRASM), a decision aid model(DAM) is proposed. This paper presents three options for EV participating in FRASM, i. e., the base mode(BM), unidirectional charging mode(UCM), and bidirectional charging/discharging mode(BCDM), based on a reasonable simplification of users' participating willingness. In BM, individual EVs will not be involved in FRASM, and DAM will assist users to set the optimal charging schemes based on travel plans under the time-of-use(TOU) price. UCM and BCDM are two modes in which EVs can take part in FRASM. DAM can assist EV users to create their quotation plan, which includes hourly upper and lower reserve capabilities and regulation market mileage prices. In UCM and BCDM, the difference is that only the charging rate can be adjusted in the UCM, and the EVs in BCDM can not only charge but also discharge if necessary. DAM can estimate the expected revenue of all three modes, and EV users can make the final decision based on their preferences. Simulation results indicate that all the three modes of DAM can reduce the cost, while BCDM can get the maximum expected revenue.

关键词： Electric vehicle(EV) frequency regulation decision aid model(DAM) utility maximization battery wear cost

A Blockchain-Based Access Control Scheme for Reputation Value Attributes of the Internet of Things

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Computers, Materials & Continua 2024年第1期78卷 1297-1310页

作者： Hongliang Tian Junyuan Tian College of electrical Engineering Northeast Electric Power UniversityJilin132012China

The Internet of Things(IoT)access controlmechanism may encounter security issues such as single point of failure and data *** address these issues,a blockchain-based IoT reputation value attribute access control scheme is ***,writing the reputation value as an attribute into the access control policy,and then deploying the access control policy in the smart contract of the blockchain system can enable the system to provide more fine-grained access control;Secondly,storing a large amount of resources fromthe Internet of Things in Inter Planetary File System(IPFS)to improve system throughput;Finally,map resource access operations to qualification tokens to improve the performance of the access control *** simulation experiments based on the Hyperledger Fabric *** simulation experimental results,it can be seen that the access control system can achieve more fine-grained and dynamic access control while maintaining high throughput and low time delay,providing sufficient reliability and security for access control of IoT devices.

关键词： Blockchain IoT access control Hyperledger Fabric

An Energy Trading Method Based on Alliance Blockchain and Multi-Signature

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Computers, Materials & Continua 2024年第2期78卷 1611-1629页

作者： Hongliang Tian Jiaming Wang College of electrical Engineering Northeast Electric Power UniversityJilin132012China

Blockchain,known for its secure encrypted ledger,has garnered attention in financial and data transfer realms,including the field of energy ***,the decentralized nature and identity anonymity of user nodes raise uncertainties in energy *** broadcast consensus authentication slows transaction speeds,and frequent single-point transactions in multi-node settings pose key exposure risks without protective measures during user *** address these,an alliance blockchain scheme is proposed,reducing the resource-intensive identity verification among *** integrates multi-signature functionality to fortify user resources and transac-tion security.A novel multi-signature process within this framework involves neutral nodes established through central *** neutral nodes participate in multi-signature’s signing and verification,ensuring user identity and transaction content *** interactions among user nodes enhances transaction efficiency by minimizing communication overhead during verification and consensus *** assessments on reliability and operational speed highlight superior security performance,resilient against conventional attack *** shows that compared to traditional solutions,this scheme has advantages in terms of running *** conclusion,the alliance blockchain framework introduces a novel approach to tackle blockchain’s limitations in energy *** integrated multi-signature process,involving neutral nodes,significantly enhances security and *** scheme’s efficiency,validated through analytical assessments and simulations,indicates robustness against security threats and improved transactional *** research underscores the potential for improved security and efficiency in blockchain-enabled energy trading systems.

关键词： Alliance blockchain multi-signature energy trading security performance transaction efficiency