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14th IEEE Global Reliability and Prognostics and Health Management Conference, PHM-Hangzhou 2023

作者： Yuan, Li Wen, Tan Su, Yan Yi, Zichao Wang, Yu State Key Laboratory of Smart Grid Protection and Control Nari Group Corporation Nanjing China Nanjing University of Aeronautics and Astronautics College of Civil Aviation Nanjing China

ISBN: (纸本)9798350301359

This paper overcomes the shortcomings of the traditional Risk assessment method of Risk Priority Number (RPN). The evaluation process is established by combining the Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS) with the cloud model theory. And applied to solve the DC charger failure mode risk assessment, analysis and determination of DC charger key failure mode and failure mechanism. Firstly, the expert assessment information of DC charger fault mode was converted into a cloud model, and then the risk assessment index and expert weight of risk assessment were calculated. Finally, the TOPSIS method was used to determine the risk priority of the fault mode, and the failure mechanism of the high-priority fault mode was analyzed to determine the failure physical model. © 2023 IEEE.

关键词： cloud model Dc charger failure mechanism risk assessment TOPSIS method

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An Feature Data Extraction Method Based on BPCA-SPCA

An Feature Data Extraction Method Based on BPCA-SPCA

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2024 IEEE International Conference on Sensing, Diagnostics, Prognostics, and control, SDPC 2024

作者： Xing, Xiangyu Yan, Bingrong Su, Yan Tang, Lingyun College of Civil Aviation Nanjing University of Aeronautics and Astronautics Nanjing China State Key Laboratory of Smart Grid Protection and Control Nari Group Corporation Nanjing China

ISBN: (纸本)9798350388855

With the increasing integration of systems and the rapid development of sensor monitoring technology, the types of monitoring data are more diverse and the number of samples are larger in flight test and operation than before. Due to the large volume and high complexity of monitoring data, the system fault diagnosis and prediction based on monitoring data is inefficient. In order to solve the problem of monitoring data redundancy, a feature extraction algorithm based on BPCA-SPCA is proposed. A system with high failure rate is selected as an example to extract the features of the system monitoring data and realize the verification of data sparseness. The experimental results show that based on BPCA-SPCA the principal components extracted monitoring data can effectively express the features of the original data, and the feature sparse vector can provide effective input information for subsequent fault diagnosis and indirectly improve the efficiency of fault diagnosis. © 2024 IEEE.

关键词： BPCA monitoring data.feature extraction SPCA

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Assessment of Reactive Power Reserve for DC Continuous Commutation Failure 6

Assessment of Reactive Power Reserve for DC Continuous Commu...

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6th International Conference on Power and Renewable Energy, ICPRE 2021

作者： Chen, Yingjie Liu, Hui Chen, Qian Xu, Wei Yang, Junjun NARI Group Corporation / State Grid Electric Power Research Institute State Key Laboratory of Smart Grid Protection and Control Nanjing China State Grid Beijing Electric Power Co. Ltd. Beijing China State Grid Beijing Electric Power Research Institute Beijing China

ISBN: (纸本)9781665449618

Real-time assessment of the risk of continuous commutation failure of the thyristor-based phase-controlled commutation direct current transmission system (LCC-HVDC) and timely preventive control measures are of great significance to ensure the safe and stable operation of the large power grid. This paper proposes a method for evaluating effective dynamic reactive power reserve of generators to deal with DC continuous commutation failure. The maximum reactive power increment of the generator corresponding to the secondary drop of the converter bus voltage is defined as the effective dynamic reactive power reserve. The effective dynamic reactive power reserve at the critical point is called the maximum effective dynamic reactive power reserve. When the system dynamic reactive power reserve is less than the reserve capacity threshold, a two-stage preventive control measure searching method is adopted. First, increase the terminal voltage of the generator and the static reactive power compensation. If the requirements are still not met, the start-up unit measures will be adopted. An example of an actual power grid verifies the effectiveness of the method. © 2021 IEEE.

关键词： Reactive power

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Reliability analysis of autonomous controllable protection device in power system 8

Reliability analysis of autonomous controllable protection d...

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8th International Conference on Power Electronics Systems and Applications, PESA 2020

作者： Li, Chen. Yutao, Qiu. Jianing, Chen. Xuliang, Huang. State Key Laboratory of Smart Grid Protection and Control China Co. Ltd Nanjing China State Grid Zhe Jiang Electric Power Co .LTD. China State Grid Zhejiang Electric Power Company Hangzhou Power Supply Company China

ISBN: (纸本)9781728193823

With the deepening of the concept of autonomous control in the power system, more and more attention is paid to the stability of the protection device itself. Compared with the primary equipment condition monitoring, the fault of the secondary protection device will be more concealed. This paper analyzes the factors affecting the reliability of protection devices, forms the life cycle prediction method of substation protection devices, and ensures the safe and stable operation of intelligent substation. Analyzed the reliability of the relay protection device related concepts, from the failure mechanism, through the establishment of joint aging failure based on the Arrhenius model and Weibull distribution model, and based on grid relay protection device, the data is using LM method for joint failure rate estimate the parameters of the model, get old equipment failure rate model of concrete, to determine the reliability of the protection device and the effective service life. An example shows that the model proposed in this paper can effectively predict the failure trend and life boundary of the device, and provide a theoretical basis for the daily maintenance of smart substation. © 2020 IEEE.

关键词： Weibull distribution

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Algorithms to Calculate the Most Reliable Maximum Flow in Content Delivery Network

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Computer Systems Science & Engineering 2022年第5期41卷 699-715页

作者： Baili Zhang Keke Ling Pei Zhang Zhao Zhang Mingjun Zhong School of Computer Science and Engineering Southeast UniversityNanjing211189China State Key Laboratory of Smart Grid Protection and Control Nanjing211106China Nari Group Corporation Nanjing211106China Department of Computing Science University of AberdeenAberdeenAB243UEUK

Calculating the most reliable maximum flow(MRMF)from the edge cache node to the requesting node can provide an important reference for selecting the best edge cache node in a content delivery network(CDN).However,SDBA,as the current state-of-the-art MRMF algorithm,is too complex to meet real-time computing *** paper proposes a set of MRMF algorithms:NWCD(Negative Weight Community Deletion),SCPDAT(Single-Cycle Preference Deletion Approximation algorithm with Time constraint)and SCPDAP(Single-Cycle Preference Deletion Approximation algorithm with Probability constraint).NWCD draws on the“flow-shifting”algorithm of minimum cost and maximum flow,and further defines the concept of negative weight *** algorithm continuously deletes the negative weight communities,which can increase reliability while keeping the flow constant in the residual *** is proven that when all negative weight communities are deleted,the corresponding maximum flow is the *** tries to approach the optimal solution to the greatest extent possible within the limited time,while SCPDAP tries to reach the probability threshold in the shortest amount of *** of these adopt the strategy of first deleting single-cycle communities(which contribute more to the reliability with lower time cost).Experiments show that,compared with SDBA,NWCD combined with the probabilistic pruning achieves an order of magnitude improvement in time cost,while SCPDAT and SCPDAP demonstrate better time performance and increased applicability.

关键词： Content delivery network uncertain graph maximum flow flow reliability

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Study on 24h Dynamic Reactive Power Optimization Considering Safety Operation Limit of Generators

Study on 24h Dynamic Reactive Power Optimization Considering...

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2019 IEEE PES Innovative Smart grid Technologies Asia, ISGT 2019

作者： Lu, Bin Xu, Xi Yu, Zhipeng Wang, Wen Gu, Xuenan NARI Group Corporation State Grid Electric Power Research Institute China NARI Technology Co. Ltd. China State Key Laboratory of Smart Grid Protection and Control China Southeast University Nanjing China

ISBN: (纸本)9781728135205

In order to solve the practical problem of 24-hours dynamic reactive power optimization in power system dispatching, according to the limit output range of generator's operation, this paper divides generator's operation into three regions in PQ mathematical model and takes the action times of discrete control equipment as global inequality constraints, finally establishes a complete 24-hours non-linear mixed integer dynamic reactive power optimization mathematical model. The simulation results show that the mathematical model in this paper can adjust the output of the generators according to the actual situation effectively when the generators are in phase-leading operation. In addition, dynamic reactive power optimization reduces the number of control equipment's action at the cost of increasing active power loss in the whole network. So, In order to ensure the safe and economic operation of power grid, it is necessary to coordinate the relationship between active power loss and the constraints of control equipment's action. This paper has positive reference significance for power system dispatching. © 2019 IEEE.

关键词： Electric power transmission networks

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Thermal simulation optimization of DC charger based on ANSYS Icepak 14

Thermal simulation optimization of DC charger based on ANSYS...

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14th IEEE Global Reliability and Prognostics and Health Management Conference, PHM-Hangzhou 2023

作者： Wang, Yu Zhou, Feiyu Wen, Tan Su, Yan Yuan, Li Wang, Ke State Key Laboratory of Smart Grid Protection and Control Nari Group Corporation Nanjing China Nanjing University of Aeronautics and Astronautics College of Civil Aviation Nanjing China State Grid Electric Power Research Institute Nanjing China

ISBN: (纸本)9798350301359

As one of the most important charging facilities for electric vehicles, DC chargers provide power supplements for electric vehicles. With the continuous development of DC chargers, the power density of their internal functional modules is also increasing. It is urgent to choose a reasonable heat dissipation method to reduce the overall temperature rise inside the DC charger and ensure its safe operation. In this paper, the 80kW DC charger is taken as the research object, and based on ANSYS Icepak thermal simulation software, the internal temperature field and fluid field of the DC charger are simulated and analyzed, and the design scheme of the DC charger is optimized by studying the heat dissipation system. Finally, the optimization scheme of the air duct structure of the system is obtained by adjusting the position of the heat dissipation fan. © 2023 IEEE.

关键词： ANSYS Icepak DC charger heat dissipation temperature thermal simulation

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Modified distance backup protection fused with DC control information 7

Modified distance backup protection fused with DC control in...

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7th Asia Conference on Power and Electrical Engineering, ACPEE 2022

作者： Gongye, Lingjiao Zhang, Dahai Li, Wei Wang, Xueqin Wu, Chuanjian Beijing Jiaotong University School of Electrical Engineering Beijing China Skl of Sgpc Nari Group Corporation State Key Laboratory of Smart Grid Protection and Control Nanjing China

ISBN: (纸本)9781665418195

The removal of the DC line may lead to power flow transfer, which leads to the wrong operation of the AC line distance III protection. To solve this problem, a modified distance backup protection that integrates DC control information is proposed. First, analyze the characteristics of DC side control information and propose a power flow transfer identification scheme that integrates DC control information. Subsequently, the modified distance backup protection is constructed using the identification results of the power flow transfer. Finally, an AC/DC hybrid model was established to verify the feasibility and fault resistance capability of the proposed scheme. © 2022 IEEE.

关键词： Electric load flow

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Analysis of Emergency control Strategy of System Frequency under Large Power Disturbance 7

Analysis of Emergency Control Strategy of System Frequency u...

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7th Asia Conference on Power and Electrical Engineering, ACPEE 2022

作者： Guang, Xu Jiahe, Yang Xuelian, Wu Zhonghui, Wan Hui, Huang Fusuo, Liu Nari Group Corporation/State Grid Electric Power Research Institute State Key Laboratory of Smart Grid Protection and Control Nanjing China Nari Group Corporation/State Grid Electric Power Research Institute Power Grid Analysis and Consulting Department Nanjing China State Grid Electric Power Research Institute Nanjing China

ISBN: (纸本)9781665418195

When large-power disturbances occur in power grids, the system frequency will shift greatly, and there may be obvious spatial-temporal distribution characteristics. By analyzing the single-machine frequency response characteristics of the system and the frequency difference between the two systems, a system frequency analysis model considering nonlinear factors under large frequency difference is proposed to estimate the maximum offset of the system frequency. It is proposed to reduce the maximum frequency offset and reduce the frequency spatiotemporal distribution characteristics by selecting the coordination method of emergency control at different locations at different times, thus improving the safety and stability of the power grid. © 2022 IEEE.

关键词： Electric power transmission networks

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A Fault Ride-Through Method of Paralleled Synchronous and Virtual Synchronous Generators in Islanded Microgrids 5

A Fault Ride-Through Method of Paralleled Synchronous and Vi...

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5th IEEE Conference on Energy Internet and Energy System Integration, EI2 2021

作者： Ru, Yanfei Zhao, Feng Jin, Zhangtao State Key Laboratory of Smart Grid Protection and Control Nari Group Corporation Nanjing211106 China College of Electrical and Information Engineering Hunan University Changsha410082 China

ISBN: (纸本)9781665434256

With the development of distributed power generation technologies, parallel operations of virtual synchronous generators (VSGs) and synchronous generators (SGs) become increasingly common in a microgrid. Due to the low overcurrent capacity of VSGs, fault ride-through (FRT) is necessary for microgrids, which makes the transient stability of SG-VSG-based microgrids be different from the traditional power system. In this paper, a new abnormal overcurrent phenomenon caused by FRT is discovered in SG-VSG-based islanded microgrids. Then, characteristics of the output current of the VSG which uses different parameters are compared and analyzed. Furthermore, an optimized FRT method is proposed, which suppresses the abnormal overcurrent. Finally, a simulation is performed to verify the effectiveness of the proposed method on the PSCAD/EMTDC. © 2021 IEEE

关键词： Synchronous generators

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