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Review of Key Technologies in New Power System Based on Artificial Intelligence Empowerment DUAN Junfeng, LI Chenkun, YAO Wenxuan, GUO Siyuan Hunan Electric Power    2024, 44 (1): 1-10.   DOI: 10.3969/j.issn.1008-0198.2024.01.001 Abstract （229）      PDF（pc） （5512KB）（404）       Knowledge map    Save Based on the important role of artificial intelligence technology in promoting the intelligence of new power systems, this paper summarizes the current application status, technical challenges, and future development directions of artificial intelligence in new power systems. Firstly,the paper introduce the characteristics and requirements of the new power system. Then, the paper discusses the key application areas of artificial intelligence in new power systems, including the security, stability and control of large power grids, integrated collaborative analysis of source network, load storage, intelligent operation, inspection and management of power systems, as well as active distribution networks and microgrids. Finally, the paper analyzes the technical challenges faced by artificial intelligence in the new power system and proposes relevant suggestions. Reference | Related Articles | Metrics

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Transient Characteristic of MOESFET Based on Cosimulation Simulink with COMSOL GAO Bing, WANG Shuai, ZHONG Yongheng, SUN Yasen, ZHANG Shangchen, ZHOU Jie Hunan Electric Power    2022, 42 (5): 1-7.   DOI: 10.3969/j.issn.1008-0198.2022.05.001 Abstract （237）      PDF（pc） （5562KB）（388）       Knowledge map    Save Power devices are one of the weak links in power electronic systems, and their failure has obvious multi-scale characteristics. It is of great significance to build a transient model that can consider the multi-scale characteristics of power devices for device condition monitoring and aging evaluation. Therefore, this paper takes MOSFET as the research object, constructs the field circuit joint simulation model of power device Simulink and COMSOL, and realizes the transient characteristic analysis of devices considering the interaction of device switching information and macro physical information by selecting the on current and on voltage drop as the model interaction information. The average temperature at the chip (shell temperature), the average temperature on the surface of the chip (junction temperature), the conduction voltage drop, the chip resistance and the maximum displacement of the solder layer are analyzed. The results show that the model can effectively consider the switching characteristics of devices and the interaction between macro fields, and lay the foundation for the digital twin model of devices. Reference | Related Articles | Metrics

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Detection Method of Metal Fitting Rust Defects for Overhead Transmission Lines Based on UAV Patrol of Deep Learning ZHANG Jiasheng, LIANG Jinxing Hunan Electric Power    2022, 42 (5): 75-78.   DOI: 10.3969/j.issn.1008-0198.2022.05.013 Abstract （188）      PDF（pc） （3274KB）（321）       Knowledge map    Save In order to improve the efficiency of UAV inspection of overhead lines and the intelligent detection efficiency of rust defects of overhead line metal fitting, a deep learning-based inspection method for rust defects of overhead lines metal fitting is proposed. Due to the characteristics of large environmental background, small target, and large difference in shooting angle and shooting light in the intelligent detection of metal fittings rust defects of overhead transmission lines, this paper uses image preprocessing algorithm to expand the data set. And YOLO is replaced by MobileNet′s backbone feature extraction network to improve the generalization ability and robustness of the algorithm, and the actual inspection images are used for experimental testing. In the test set validation, when the confidence threshold is 0.5, the P value is 0.92, the R value is 0.84, and the AP value is 91.34%. The results show that this method has a good detection effect on the rust defects of overhead line metal fittings, and can provide reference for the assessment of equipment health status. Reference | Related Articles | Metrics

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Research and Implementation of Synchronous Space Vector Modulation Algorithm for Photovoltaic Direct Drive Air Conditioner LIN Baowei, YANG Maotao, ZENG Wenwei, ZHAO Zhigang, LIN Jing Hunan Electric Power    2020, 40 (4): 1-6.   DOI: 10.3969/j.issn.1008-0198.2020.04.001 Abstract （215）      PDF（pc） （3528KB）（316）       Knowledge map    Save This paper studies the synchronous space vector modulation (SVPWM) algorithm of photovoltaic direct-drive air conditioners, and gives the implementation scheme of synchronous modulation. And the effectiveness of the synchronous modulation scheme is verified by simulation.Finally, by applying SVPWM modulation in the vector control system of permanent magnet synchronous motor, the stability of the modulation method in closed-loop control with low switching frequency is verified. Reference | Related Articles | Metrics

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Electrodynamic Calculation of Cable Short Circuit Based on Finite Element Electromagnetic Simulation XU Binbing, CHEN Ziyao, LIU Yubin, LEI Jiacheng, QIN Rui, YANG Xin Hunan Electric Power    2023, 43 (1): 23-29.   DOI: 10.3969/j.issn.1008-0198.2023.01.004 Abstract （115）      PDF（pc） （6715KB）（237）       Knowledge map    Save When a short-circuit fault occurs in the cable line, the mechanical properties of the cable bracket and hardware will be threatened under the action of short-circuit electric power. The traditional method of calculating cable short-circuit electric force is formula method. The formula method can only calculate the maximum short-circuit electric force, and there are limitations such as single solution object and inability to reflect the change of force with time. In this paper, the finite element calculation method based on electromagnetic coupling is used to establish the finite element calculation model of cable short-circuit electrodynamic force. Based on Maxwell 's electromagnetic theory and Gauss divergence theorem, the transient electromagnetic field analysis of the cable is carried out, and the change of short-circuit electrodynamic force on the cable with time is obtained. Compared with the calculation results of the formula method, there is only 2.11% error. The results show that the calculation method of short-circuit electrodynamic force based on finite element electromagnetic simulation can intuitively obtain the distribution and vibration frequency of electrodynamic force at each moment during short circuit. The electrodynamic calculation method of finite element electromagnetic simulation can be applied to short-circuit analysis of other fault types. Reference | Related Articles | Metrics

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Application of Distributed Energy Storage in Distribution Networkand Its Economic Evaluation ZHAO Yuting, LYU Dangzhen, WAN Dai, ZHAO Yongsheng Hunan Electric Power    2022, 42 (5): 53-59.   DOI: 10.3969/j.issn.1008-0198.2022.05.009 Abstract （160）      PDF（pc） （1120KB）（228）       Knowledge map    Save According to the research and development and application status of distributed energy storage power station in distribution network, the application scenario and price system of distributed energy storage power station in distribution network are analyzed, and the principle of location and capacity selection of distributed energy storage power station in distribution network is put forward.This paper establishes a mathematical model for economic evaluation of distributed power stations in distribution network, makes economic evaluation based on an example of distributed energy storage power stations in distribution network,and proposes suggestions on improving the comprehensive benefits of distributed power stations in the distribution network. Reference | Related Articles | Metrics

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Design and Simulation of Equalization Circuit for Lithium-Ion Battery ZHU Hao, LIAO Honghui, E Jiaqiang, DENG Yuanwang Hunan Electric Power    2022, 42 (4): 28-32.   DOI: 10.3969/j.issn.1008-0198.2022.04.006 Abstract （142）      PDF（pc） （3032KB）（226）       Knowledge map    Save In applications such as energy storage plants and pure electric vehicles, cell units are integrated in the battery pack in series and parallel,the battery packs may not be consistent with each other when in use, and this inconsistency can affect battery life and range. Aiming at this phenomenon, the paper designs the balanced topology circuit between the module and the module, analyzes the balanced principle of the designed circuit,builds the energy transfer model and the module internal balanced model in the Simulink/Simpowersystem, and simulates the equilibrium topology.The results show that the designed equalization system can realize the energy equalization of the battery. Reference | Related Articles | Metrics

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Analysis and Research of On-Line Energy Consumption Monitoring Model for Thermal Power Units NIE Tao, SHAO Feng, YANG Wenzheng, HE Xinrong , WANG Zhong′ao Hunan Electric Power    2023, 43 (2): 60-65.   DOI: 10.3969/j.issn.1008-0198.2023.02.010 Abstract （90）      PDF（pc） （1192KB）（215）       Knowledge map    Save Because of the limitation of on-line energy consumption measurement condition and instrument measurement precision, the coal consumption of on-line monitoring system usually has big error.To solve this technical problem, this paper adopts the state equation of thermal economy of power plant to dynamically solve the steam turbine heat rate, applying the idea of energy mass balance, the steam water distribution matrix equation of the whole thermal system is established.At the same time, the dynamic fluctuation characteristics of boiler efficiency are deeply studied, the factors of coal quality ash and heat dissipation are analyzed , the theoretical calculation models of exhaust heat loss, solid incomplete combustion heat loss and heat dissipation loss are established.For the dynamic calculation of auxiliary power consumption rate, the emphasis is on the accuracy of the electric meter and the allocation method of the public part of the power supplied to the factory. The online calculation accuracy of the unit energy consumption model is verified and the test results show that the on-line energy consumption calculation and monitoring model can meet the accuracy requirements of ASME standards. Reference | Related Articles | Metrics

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Fault Analysis and Management of Feedwater Pump Turbine Shaft Sealing System for a 1 000 MW Unit YU Xinggang, WEI Haifeng, ZHU Taichun, GUO Xuhong, JIANG Bohua Hunan Electric Power    2022, 42 (5): 119-122.   DOI: 10.3969/j.issn.1008-0198.2022.05.021 Abstract （83）      PDF（pc） （1475KB）（214）       Knowledge map    Save A 1 000 MW unit in a newly-built coal-fired power plant adopts a steam-driven feed water pump with a capacity of 100% boiler maximum continuous rating. During commissioning, the shaft seal system of the feed water pump turbine of this unit has the faults of water entrainment of shaft seal steam and abnormal noise of the shaft seal pipe at the side of the feed water pump. Through adjustment and analysis, it is found that the causes of the above-mentioned failures are unreasonable design of shaft seal steam return pipe and imperfect installation of shaft seal steam pipe sleeve in condenser. The fault of shaft seal system of feed water pump turbine has been successfully solved by installing hydrophobic water seal cylinder at the lowest point of shaft seal steam return pipeline and installing heat insulation on shaft seal steam pipeline in condenser. Reference | Related Articles | Metrics

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Research of Insulation Monitoring Methods for Electric Vehicle Power Battery Pack DENG Yuanwang, YIN Huichun, E Jiaqiang, LIU Shuai, ZHU Hao Hunan Electric Power    2023, 43 (1): 46-49.   DOI: 10.3969/j.issn.1008-0198.2023.01.008 Abstract （135）      PDF（pc） （3081KB）（209）       Knowledge map    Save As the demand for battery pack energy storage continues to increase and its voltage plateau rises, the real-time monitoring of the insulation performance of high-voltage systems becomes more and more important. In this paper, several common methods of insulation resistance detection are analyzed, the insulation resistance detection method of the balanced-unbalanced bridge is proposed, and Multisim is used to build a whole vehicle insulation simulation model to analyze the feasibility of the insulation resistance detection method of a balanced-unbalanced bridge. Reference | Related Articles | Metrics

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Analysis on Over Tripping Accident of Main Transformer Caused by a Line High Resistance Grounding Fault YIN Chaoyong, XU Hao, XU Liqiang, LI Hui Hunan Electric Power    2020, 40 (4): 51-54.   DOI: 10.3969/j.issn.1008-0198.2020.04.012 Abstract （143）      PDF（pc） （2720KB）（209）       Knowledge map    Save When the high resistance ground fault occurs in the line, the fault characteristics are not obvious. At present, it is difficult for the protection device with single terminal electric quantity to realize the reliable and quick operation of the wholeline, and identify the fault.This paper introduces a single-phase high resistance grounding fault of 110 kV transmission line, analyzes the protection action of relevant lines and main transformer after the fault, points out the fault cause. It draws a conclusion that when the high resistance grounding fault is unstable and stable, protection devices may be refused to move, and its selectivity and sensitivity is difficult to meet the requirements. Reference | Related Articles | Metrics

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Summary of Reliability Research on High Voltage Electrical Device in Substation MA Zhaoxing, CHEN Hao, TANG Yi, SHA Haoyuan, JIANG Minyi Hunan Electric Power    2023, 43 (2): 53-59.   DOI: 10.3969/j.issn.1008-0198.2023.02.009 Abstract （133）      PDF（pc） （1104KB）（209）       Knowledge map    Save Based on the reliability research of high-voltage electrical equipment in substations, this paper introduces the development of the reliability research of high-voltage electrical equipment, discusses the reliability analysis methods of common electrical equipment, and compares the advantages and disadvantages of the analytical and analog methods, the optimal application situation is analyzed, and the combination method and state method under complex system are studied. The future trend of reliability analysis based on multi-methods cross-fusion is prospected. Reference | Related Articles | Metrics

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Research on Lithium Battery Parallel System and Level Difference Coordination in Substation ZHAO Wenqin, XIAO Hui, ZHANG Maolin, LI Yihang, LONG Feiyu, WEN Zhang Hunan Electric Power    2022, 42 (4): 23-27.   DOI: 10.3969/j.issn.1008-0198.2022.04.005 Abstract （135）      PDF（pc） （2129KB）（208）       Knowledge map    Save The DC system is the last barrier of the substation power supply system, and its power supply reliability directly affects the operation of the entire substation. Based on a 220 kV substation, using lithium iron phosphate batteries to replace the original lead-acid batteries, this article analyzes the characteristics and applications of lithium iron phosphate batteries advantages and feasibility, studies the topological structure of the DC system, and calculates the short-circuit current of the upgraded DC system. According to the calculation results, and referring to the circuit breaker tripping curve, the paper analyzes the rationality of its level difference coordination, and points out the defects of the converter and the fuse. It provides a basis for the further upgrade and transformation of the DC system. Reference | Related Articles | Metrics

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Effect of Organic Pollutant Infiltration on Anti-Flashover Performance of Methyl Silica Superhydrophobic Coatings WANG Shengwu, ZOU Qiaoge, LI Li, CHEN Junwu, XIE Yi Hunan Electric Power    2023, 43 (2): 3-7.   DOI: 10.3969/j.issn.1008-0198.2023.02.001 Abstract （81）      PDF（pc） （3667KB）（201）       Knowledge map    Save The deposition and infiltration of organic pollutants on the surface of methyl silica superhydrophobic coatings will lead to a decrease in the self-cleaning properties of the coatings, which in turn will lead to a decrease in the insulation strength of the coatings under dirty and wet environmental conditions. There is a lack of research on the effect of organic fouling on the insulation strength of methyl silica superhydrophobic coatings. The insulation strength of the coating samples under dirty and wet conditions is reflected by measuring the leakage current amplitude of the coating samples after they are wetted with alkane organic substances in different degrees and ways. The results show that the leakage current amplitude of the surface of methyl silica superhydrophobic coating increases by more than 50% when the infiltration area of organic pollution is increased to 3 times under the experimental conditions. The leakage current amplitude of the coating is decreased by about 16% by increasing the dispersion degree of organic pollution sites. Under the experimental conditions of heavy organic infiltration, the static contact angle and rolling angle of methyl silica super-hydrophobic coating drops are decreased by 10° and increased by more than 7° respectively. Reference | Related Articles | Metrics

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Power Flow Calculation Method in Loop-Closing Distribution Network Based on Bus Voltage Phasor Acquisition CHEN Chenggong, ZHU Yulan, PANG Muchan Hunan Electric Power    2023, 43 (2): 102-107.   DOI: 10.3969/j.issn.1008-0198.2023.02.017 Abstract （76）      PDF（pc） （2555KB）（201）       Knowledge map    Save The traditional calculation method relying on power grid modeling and parameter accuracy is not suitable for the power flow calculation in loop-closing distribution network.To solve this problem, a new power flow algorithm based on bus voltage phasor acquisition is proposed, which can realize the on-line calculation of power flow in distribution network conveniently. The on-line computing module developed based on the algorithm has a good effect, which verifies the validity and practicability of the algorithm. Reference | Related Articles | Metrics

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Cause Analysis and Preventive Measures of Wind Turbine Blade Tower Sweeping LUO Yanfei, XIAO Changyuan , SUN Maowen, LUO Shengxi, ZHANG Hualian Hunan Electric Power    2023, 43 (1): 116-120.   DOI: 10.3969/j.issn.1008-0198.2023.01.020 Abstract （246）      PDF（pc） （4564KB）（197）       Knowledge map    Save In recent years, there have been a number of blade tower sweeping failures of wind turbine in China, which have seriously affected the safe operation of wind turbines, and also brought a lot of economic losses. This paper analyzes the causes of blade tower sweeping failure in a wind farm from the aspects of clearance design, hoisting maintenance, blade quality, unit operation control, site adaptability, simulation restoration, etc. It is determined that the blade tower sweeping in the wind farm are caused by turbulence overrun, negative shear, and blade installation angle dislocation. Preventive measures are given for different tower sweeping causes, and some suggestions are put up for the clearance design of new models. Reference | Related Articles | Metrics

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Analysis of Loop Network Fault Harm in DC Power System CAO Wenbin, LUO Wei, CHEN Ruizhen Hunan Electric Power    2022, 42 (4): 110-114.   DOI: 10.3969/j.issn.1008-0198.2022.03.022 Abstract （111）      PDF（pc） （1165KB）（196）       Knowledge map    Save DC loop network fault is one of the common forms of insulation faults in DC power systems. This article analyzes the causes, types and hazards of ring network faults. Focusing on the equivalent circuit of the DC power system, the voltage manifestations of various ring network faults are expounded from the perspective of circuit structure, and the essence of loop network fault hazards is revealed. Finally, according to the physical phenomenon of the loop network fault, the specific operation method of the loop network fault is given. Reference | Related Articles | Metrics

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Insulator Pollution Monitoring Based on Acoustic Signal and One-Dimensional Convolutional Neural Network LI Zhenhua, LI Hao, HUANG Jingguang, ZHANG Lei, WU Lin Hunan Electric Power    2022, 42 (4): 18-22.   DOI: 10.3969/j.issn.1008-0198.2022.04.004 Abstract （140）      PDF（pc） （2465KB）（190）       Knowledge map    Save Aiming at the problem of discharge mode monitoring of polluted insulators in high voltage transmission lines,a new one-dimensional convolutional neural network structure (1D-CNN) is designed for monitoring the discharge patterns of fouled insulators in high-voltage lines, and a fouled insulator discharge pattern monitoring method based on acoustic emission signals and 1D-CNN is proposed. After preprocessing the acoustic emission signals collected in the laboratory under different discharge states, the convolutional neural network is used to perform adaptive feature extraction and feature dimensionality reduction on the discharge signal samples to reduce the training model parameters and computation, and finally the Softmax function is used to classify the prediction results. The recognition results show that the model can achieve a recognition rate of more than 99.84%, which effectively solves the process of manual preprocessing of data in the traditional insulator fouling degree monitoring method and can be effectively applied to the task of fouling insulator discharge pattern monitoring. Reference | Related Articles | Metrics

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Research on Grid Source Coordination Technology Problem in New Energy Power Station LIU Hui, XIE Wei, LI Chengshuai, GUO Feiyang Hunan Electric Power    2022, 42 (4): 81-84.   DOI: 10.3969/j.issn.1008-0198.2022.04.016 Abstract （105）      PDF（pc） （2350KB）（185）       Knowledge map    Save To build a new electric power system, it is necessary to solve the impact of new energy power stations on the stability of power systems, and improve the grid-source coordination performance of new energy sources.Based on the on-site grid-related test data, the test results of power quality, active and reactive power control performance, SVG performance, fault traversal performance and grid adaptability of the new energy power station are statistically analyzed.It is pointed out that the testing project of fault traversal performance and adaptability of power grid is the weak point of the current coordination and management of network sources of new energy field stations, and it should be the key work in the future.The typical problems of fault traversal and network adaptability are summarized and analyzed, and the corresponding countermeasures are put forward from the managerial and technical levels to support the transformation and development of power system. Reference | Related Articles | Metrics

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Design and Application of Complex Terrain and Omni-Directional Modular Quick Installation Insulating Tower Platform BAI Jianfeng, LEI Dongyun, XIAO Liyong, LI Jinliang Hunan Electric Power    2022, 42 (4): 64-69.   DOI: 10.3969/j.issn.1008-0198.2022.04.013 Abstract （104）      PDF（pc） （4301KB）（184）       Knowledge map    Save With the increasing demand for reliable power supply in distribution network, it is urgent to carry out uninterrupted power supply in the whole region. In order to adapt to the live working environment of power distribution under different terrain, the advantages and disadvantages of common live working insulation platforms are compared and analyzed, and an complex terrain and omni-directional modular quick installation insulation tower platform is designed in this article. A tower body, a hoop holding device, an auxiliary platform and a working platform is comprised in the device.Modular tower section is adopted, inverted or rotary installation mode is designed, and the method of fixing relying on concrete pole is designed in this design. It can meet the three main functional requirements of quick disassembly and quick assembly, multi-purpose and heavy load. The device is suitable for the live working environment of 10 kV overhead distribution line under complex and changeable terrain. The problems of difficult installation and connection of common insulation platforms in rural areas, high requirements for ground flatness, small application scenarios are solved. Reference | Related Articles | Metrics

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Research on Monitoring and Management of Wind Power Generation Capacity in Hunan Power Grid CHEN Haoqi, WU Yuxiang, FAN Jiahong, QIAN Jun, CHEN Bin, ZHU Shu, ZHANG Jinfan Hunan Electric Power    2023, 43 (2): 97-101.   DOI: 10.3969/j.issn.1008-0198.2023.02.016 Abstract （162）      PDF（pc） （4797KB）（178）       Knowledge map    Save In view of the current situation and existing problems of wind power capacity monitoring technology in Hunan power grid, a wind power capacity monitoring algorithm and system architecture based on abnormal data identification are proposed. The feasibility of the algorithm is verified by historical data, which realizes real-time monitoring of wind power plant capacity and automatic detection and identification of wind power plant abnormal data.Based on the monitoring system, the supporting management suggestions are put forward to scientifically guide the improvement of the wind power management level of Hunan power grid, which can improve the wind power supply support ability and promote the development of wind power anti-ice technology. Reference | Related Articles | Metrics

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Electromagnetic-Fluid-Thermal Field Analysis of Power Cable under Vertical Laying Mode QU Bo, YANG Juntao, LI Xin, XIANG Xingyao, SHU Shengwen Hunan Electric Power    2023, 43 (2): 24-31.   DOI: 10.3969/j.issn.1008-0198.2023.02.005 Abstract （84）      PDF（pc） （4304KB）（175）       Knowledge map    Save The temperature distribution is one of the key factors that determine the operation of the power cable, and it is mainly affected by the running current, the laying mode and the operating environment. In order to study the temperature distribution characteristics of cables under the vertical laying mode, the paper takes the cable shafts of high-rise buildings as the research object, and builds a simplified three-dimensional multi-physics simulation model of the cable shafts. The finite element method is used to calculate the fluid and temperature distribution inside the cable shafts, and the temperature variation trend is analyzed. Then, the influence of factors such as running current and fire blocking material on the temperature distribution of the cable is comparatively studied. The research results show that compared with the horizontal laying mode, the vertical laying of the cable is more susceptible to the influence of the air flow in-side the cable shaft, resulting in a large difference in the temperature distribution between different parts of the cable. At the same time, the increase of load current and the addition of fire blocking materials will cause the increase of cable temperature and the change of temperature distribution between different floors. Reference | Related Articles | Metrics

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Analysis of a Grounding Fault Caused by Wiring Error in DC System CHEN Ruizhen, XIE Zhihao, GAO Tipan, WANG Xiao, CHEN Zhilong Hunan Electric Power    2020, 40 (4): 47-50.   DOI: 10.3969/j.issn.1008-0198.2020.04.011 Abstract （154）      PDF（pc） （1915KB）（171）       Knowledge map    Save The DC system of substation provides reliable power for protection device, signal device and automatic safety device. It is an important factor of relay correct operating and its fault may affect the safe operations of the power system. According to a metallic ground fault DC bus negative pole occured during the repair work of a battery, the fault cause are analyzed, and some suggestions are put forward for the completion acceptance and routine test of DC systems. Reference | Related Articles | Metrics

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Design of Digital Drive of High Power High Voltage DC Circuit Breaker Based on IGBT Device ZENG Jinhui, FAN Yangjie, HE Dong, LIU Xiang, LIAO Xiaobin Hunan Electric Power    2022, 42 (5): 8-15.   DOI: 10.3969/j.issn.1008-0198.2022.05.002 Abstract （158）      PDF（pc） （5057KB）（170）       Knowledge map    Save Aiming at the application of high power multi-switch, a new multi-function IGBT digital driver based on field programmble gate array(FPGA)is proposed, which is efficient, safe and reliable.The driver can make use of the full insulated gate bipolar transistor(IGBT)state detection circuit, multi-channel signal fault detection and protection circuit. In the test of multi-switch and high power 10 kV/5 kA circuit breaker, it is proved that the driver can ensure the validity of IGBT's functions such as voltage sharing, current sharing and temperature detection.The function of simultaneous shutdown is realized in 6.4 μs, the switching process of IGBT is optimized, and the safety and reliability of the whole circuit breaker is ensured. Reference | Related Articles | Metrics

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Influence and Optimization of Shielding Fitting on Voltage Distribution of Series Multi-break Mechanical Switch of Hybrid Circuit Breaker WANG Huaqing, HUANG Daochun, SHUANG Mingjing, Li Huipeng, CHEN Xin, QIU Yiqun Hunan Electric Power    2022, 42 (4): 1-6.   DOI: 10.3969/j.issn.1008-0198.2022.04.001 Abstract （142）      PDF（pc） （2403KB）（170）       Knowledge map    Save In order to study the influence of shielding fitting on the voltage distribution of series multi-break mechanical switch of hybrid DC circuit breaker, and provide support for the voltage sharing design of fast series multi-break mechanical switch of hybrid HVDC circuit breaker, a typical ±200 kV hybrid DC circuit breaker model is established in this paper. The influence of the power electronic module, the energy absorption module and the shielding fitting on the voltage distribution characteristics of the break of the fast mechanical switch is analyzed by using the electrostatic field simulation, especially the influence of the structural parameters and arrangement of the shielding fitting on the voltage distribution characteristics of the break. The results show that the shielding fitting has the greatest influence on the voltage distribution between the breaks, the voltage distribution between the breaks can be effectively improved by means of the completely enclosed structure of the top layer shield, and reduce the distance between the top layer shield and the fast mechanical switching unit. Based on the simulation results, the structure parameters and arrangement mode of ±200 kV hybrid shielding DC circuit breaker fitting are optimized, the optimized voltage percentage of the high voltage side break decreases from 59.97% to 52.32% and it shows the effectiveness of the optimization measures. The results of this paper can provide a reference for the design of voltage sharing design of series multi-break mechanical switches for hybrid DC circuit breakers. Reference | Related Articles | Metrics

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Treatment of Oily Wastewater from Substation Accident Oil Pool Based on Process of Magnetic Flocculation and Electrocatalytic Oxidation WAN Tao, CHE Yao, LIU Heng, ZHAO Ruidun, ZHU Qiaoyun, XIANG Jingjing, ZHANG Lei Hunan Electric Power    2022, 42 (5): 69-74.   DOI: 10.3969/j.issn.1008-0198.2022.05.012 Abstract （112）      PDF（pc） （2729KB）（168）       Knowledge map    Save In view of the characteristics of the oil pool wastewater containing a large amount of mineral insulating oil in substation, the combined process of magnetic flocculation and electrocatalytic oxidation is adopted to treat the oil containing wastewater, the flocculation effect of magnetic flocculation and conventional flocculation is compared, and the effect of electro-catalytic oxidation process parameters on oil removal rate in oil-bearing wastewater is studied. The results of dynamic simulation tests show that the combined process has a good effect on the treatment of oil-containing wastewater from the oil pool of a substation accident. The removal rates of oil, chemical oxygen demand,turbidity and ammonia nitrogen are 96.99%,85.98%, 90.85% and 78.86% respectively. The effluent quality meets the first-class standard of Comprehensive Wastewater Discharge Standard. Reference | Related Articles | Metrics

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Control Strategy of LCL Grid-Connected Inverter Based on Improved Weighted Current Control LING Zhiyong, ZHOU Zhifei, LI Shengqing, YAO Hongde Hunan Electric Power    2023, 43 (2): 39-45.   DOI: 10.3969/j.issn.1008-0198.2023.02.007 Abstract （115）      PDF（pc） （4395KB）（168）       Knowledge map    Save Aiming at the problems that the traditional weighted average current (WAC)control strategy does not consider the digital control delay, and causes the phase lag of the system, which leads to the reduction of system bandwidth and poor robustness, the WAC control strategy of combination of quasi-proportional resonance control and lead compensator is proposed. Firstly, the capacitor current feedback is introduced to suppress the reverse resonance peak. Secondly, the lead compensator is connected in series at the transfer function of the inverter bridge to improve the phase margin of the system. Finally, the quasi-proportional resonant controller is used as a current regulator to Increase the fundamental frequency gain and reduce the static error of the system. It is verified by simulation that the proposed control strategy has good adaptability to weak power grids, and the harmonic distortion rate of grid-connected current is reduced from 1.84% to 0.26%, thereby enhancing the robustness of the system and improving the quality of grid-connected current. Reference | Related Articles | Metrics

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An On-Line Voltage Stability Assessment Method based on Particle Swarm Optimization Support Vector Regression Prediction LI Shuaihu, ZHAO Xiang , JIANG Yunchen Hunan Electric Power    2022, 42 (5): 22-28.   DOI: 10.3969/j.issn.1008-0198.2022.05.004 Abstract （156）      PDF（pc） （2746KB）（164）       Knowledge map    Save In this paper, an online voltage stability evaluation method based on particle swarm optimization support vector regression(PSO-SVR) for large power grid is proposed. The traditional voltage stability evaluation method based on deep neural networks(DNN) model is improved to the SVR model optimized by PSO to predict the impedance modulus margin index.This method takes advantage of SVR model′s advantages of strong learning ability and low generalization error rate, and it can also learn the features of samples well in the case of small samples.In order to overcome SVR model is very sensitive to parameter adjustment and function selection.The proposed method uses PSO algorithm to optimize the hyper-parameters of SVR model, which can make the SVR model better learn the nonlinear relationship between power grid operation data and impedance modulus margin value.Finally, the proposed method is validated in IEEE 118 node system, and the accuracy of the proposed method is higher than that of DNN model-based evaluation method. Reference | Related Articles | Metrics

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Non-destructive Identification Method of Transformer Windings Based on Multiple Points Temperature DING Xiaofei, GUO Jing, TANG Haolong Hunan Electric Power    2023, 43 (1): 41-45.   DOI: 10.3969/j.issn.1008-0198.2023.01.007 Abstract （101）      PDF（pc） （4292KB）（162）       Knowledge map    Save To ensure a fair market competition mechanism and avoid aluminum winding transformers from impersonating copper winding transformers, which affects the safety and stability of power system operation, it is important to identify transformer winding materials. To avoid transformer structure damage and identify winding material accurately and effectively, this paper proposes a non-destructive identification method of transformer copper and aluminum winding material based on multiple temperature points, which identifies the winding material based on the resistance coefficient method combining with the results of multiple test points. The experiment results on a copper winding transformer and an aluminum winding transformer show that the proposed method is accurate and effective, and can be further extended to large-scale engineering practice. Reference | Related Articles | Metrics

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Comprehensive Evaluation Method of Regulation Performance of Industrial Load Participating in Power Grid Interaction LIU Hanqing, SHEN Yangwu, LIAO Siyang, LEI Xiao, YUE Xuxin, SUN Jieyi, CHEN Yaling, XU Jian Hunan Electric Power    2023, 43 (1): 35-40.   DOI: 10.3969/j.issn.1008-0198.2023.01.006 Abstract （143）      PDF（pc） （4505KB）（160）       Knowledge map    Save In order to evaluate the performance of industrial load participating in power grid regulation, a comprehensive evaluation index system is constructed, which includes three aspects: potential evaluation, economic evaluation and control effect evaluation. The evaluation index calculation method combining subjective and objective is put forward, which can reasonably calculate the index combination weight. The evaluation system is applied to three kinds of typical industrial loads, and the validity of the evaluation index and the proposed analysis method is verified. Reference | Related Articles | Metrics

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Capacity Optimization Configuration of Grid-Connected Wind-Solar-Hydrogen-Storage Microgrid ZHAO Na, ZHANG Lian, WANG Shibin, LI Duo, HUANG Wei Hunan Electric Power    2023, 43 (4): 48-55.   DOI: 10.3969/j.issn.1008-0198.2023.04.007 Abstract （79）      PDF（pc） （1469KB）（160）       Knowledge map    Save A single type of energy storage device is difficult to take into account the advantages of multiple types of energy storage devices, while the hybrid energy storage system can integrate the technical and economic advantages of different types of energy storage. Aiming at the optimal configuration of hybrid energy storage based on battery and hydrogen energy storage in grid-connected mode, economic and environmental protection are taken as the objective function, the analytic hierarchy process is used to solve the multi-objective weight problem, and the particle swarm optimization algorithm is used to solve the optimal configuration of microgrid capacity. Different energy storage configuration schemes are analyzed and compared by economy and evaluation index. The results show that the cost of hybrid energy storage is 2.46% and 10.02% lower than that of single battery and hydrogen energy storage. The self-balancing rate is 7.65% and 23.89% higher than that of single battery and hydrogen energy storage, and the redundancy is 19% and 38.16% lower than that of single battery and hydrogen energy storage. Reference | Related Articles | Metrics

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Application of Electro-Regeneration Ion Exchange Technology in On-Line Measurement of Hydrogen Conductivity GU Zhenyang, LI Limin, HE Yuning, SUN Jihui, LI Chenghao, DONG Weihu, DAI Xin , YANG Jeili Hunan Electric Power    2022, 42 (5): 64-68.   DOI: 10.3969/j.issn.1008-0198.2022.05.011 Abstract （82）      PDF（pc） （2409KB）（159）       Knowledge map    Save Conventional online measurement method of hydrogen conductivity uses cation exchange resin column for pretreatment, and when the cation resin fails, it needs to be regenerated. This work not only consumes labor, but also easily introduces additional errors of exchange column, which reduces the accuracy of hydrogen conductivity measurement. To solve the above problems, the electric regeneration ion exchange technology is applied to the online measurement of hydrogen conductivity, and the hydrogen conductivity meter does not need to be replaced or regeneration of resin in the follow-up maintenance work, thus realizing the continuous online accurate measurement of hydrogen conductivity. The application results of regenerative ion exchange technology in online measurement of hydrogen conductivity show that this technology can save a lot of manpower and improve the accuracy and continuity of online measurement of hydrogen conductivity. Reference | Related Articles | Metrics

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Design and Verification of Balance Performance for 550 kV High Capacity Ice-Melting Disconnector WU Shang, TANG Xueping, WANG Chunhua, MA Weijun, WU Qigang Hunan Electric Power    2022, 42 (4): 56-59.   DOI: 10.3969/j.issn.1008-0198.2022.04.011 Abstract （92）      PDF（pc） （1884KB）（159）       Knowledge map    Save The ice melting disconnector of 550 kV line is installed outdoors. When the high-voltage transmission line needs ice melting treatment, the ice melting disconnector is also likely to be in icing state. Therefore, it is particularly important to meet the balance performance design under different working conditions. According to the requirements of product technical parameters, the structure of 550 kV high-capacity ice melting disconnector is designed. On this basis, the balance performance of ice melting disconnector under different working conditions is designed and checked. The results show that the balance performance of the 550 kV high-capacity ice melting disconnector meets the operation requirements under normal operation and 20mm icing conditions, and the balance performance design method adopted is generally applicable. Reference | Related Articles | Metrics

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Development of Mobile Energy Storage Vehicle Based on Super Capacitor Battery WU Chuanping, ZHOU Tiannian, LIU Yu, ZHU Hongzhang Hunan Electric Power    2023, 43 (2): 66-70.   DOI: 10.3969/j.issn.1008-0198.2023.02.011 Abstract （103）      PDF（pc） （5822KB）（156）       Knowledge map    Save Aiming at a new type of mobile energy storage vehicle using electrical double-layer capacitor, this paper introduces the electrical double-layer capacitor characteristics, the structure of mobile energy storage vehicle and the electrical double-layer capacitor package assembly scheme, puts forward the control method and working mode of energy storage power converter, designs the fire protection system of the device, and carries out the functional test on electrical double-layer capacitor mobile energy storage vehicle. The test results show that electrical double-layer capacitor mobile energy storage vehicle runs well in charging, discharging and islanding mode when connected to the grid, with high energy conversion efficiency and good application prospects. Reference | Related Articles | Metrics

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Study on Natural Convective Flow Heat Transfer in Supercritical Carbon Dioxide Cavity YE Maojing, WU Tianyu, LIU Kairui, WANG Limin, CHE Defu Hunan Electric Power    2023, 43 (4): 1-8.   DOI: 10.3969/j.issn.1008-0198.2023.04.001 Abstract （86）      PDF（pc） （4176KB）（154）       Knowledge map    Save Horizontal flow of supercritical carbon dioxide (S-CO2) will flow stratification under heating or cooling conditions, resulting in different heat transfer phenomena at the top and bottom of the tube. In order to study the flow heat transfer behavior driven by upward lift in vertical flow direction, the development process of S-CO2 natural convection and the influence of pressure, pipe diameter and temperature interval on the development process are studied based on a two-dimensional circular cavity physical model. The results show that the development process of flow heat transfer away from the pseudo-critical temperature range is relatively stable compared with the pseudo-critical temperature range. In the pseudo-critical temperature range, the higher the pressure, the faster the heat transfer development process. In the pseudo-critical temperature range, the larger the diameter of the pipe, the longer the time for heat transfer to reach stability, and the more intense the main flow zone is in the initial stage of development. Reference | Related Articles | Metrics

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LCL Solar Inverter Control Design for Weak Power Grids ZENG Lin, ZHU Zan, XU Yong, XIANG Yunkun, HE Zhe Hunan Electric Power    2023, 43 (2): 90-96.   DOI: 10.3969/j.issn.1008-0198.2023.02.015 Abstract （91）      PDF（pc） （3180KB）（150）       Knowledge map    Save The connection of a distributed generation (DG) unit to a weak power grid is challenging due to stability issues resulted from the uncertainty of system impedance. This paper designs controller to improve the performance of grid-connected current feedback control based on μ method. In order to decouple active and reactive components in control system, a multi-input multi-output model reflecting the interaction between the components of d and q is established. The decoupling requirement, together with steady-state error and overshoot is transformed into the design problem of controller. By employing the μ method, the paper designs a robust feedback controller to meet the all requirements. Simulations show that the controller not only guarantees the robust stability and robustness of the system under the uncertainty of the inductance of the power grid, but also realizes the decoupling of the d and q components of the current. Reference | Related Articles | Metrics

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Optimal Efficiency Control Method for Large-Scale Hydrogen Production System from Renewable Energy MENG Xin, CHEN Maolin, WANG Xiongzheng, YANG Haoran Hunan Electric Power    2023, 43 (3): 2-8.   DOI: 10.3969/j.issn.1008-0198.2023.03.001 Abstract （112）      PDF（pc） （7877KB）（146）       Knowledge map    Save Large scale hydrogen production from renewable energy is an important technical means to achieve renewable energy consumption and suppress fluctuations. Aiming at the optimal operation of large-scale intermittent renewable energy hydrogen production system, an efficiency optimization control method of parallel hydrogen production units is proposed. Firstly, the efficiency model of hydrogen production units is established. Secondly, by constructing the efficiency optimization objective function and constraints of multiple parallel hydrogen production units, the optimal power distribution value of each parallel hydrogen production device at different input power is optimized by exhaustive optimization algorithm. Finally, the effectiveness and feasibility of the method are verified by MATLAB simulation, and its operating efficiency are compared with the power sharing and hierarchical switching modes. The results show that the efficiency optimization control method can effectively improve the operation efficiency of the parallel system under fluctuating power. Reference | Related Articles | Metrics

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Identification of Hydropower Unit Shafting Fault Based on Multifractal Spectrum and Support Vector Machine MENG Fancong , JI Junjie, XUE Xiaobing, YAO Hangyu, HU Fei, PAN Weifeng, BAI Liang Hunan Electric Power    2022, 42 (5): 114-118.   DOI: 10.3969/j.issn.1008-0198.2022.05.020 Abstract （92）      PDF（pc） （1492KB）（145）       Knowledge map    Save A method based on multifractal spectrum and support vector machine is proposed for fault identification of shafting system of hydropower units. Firstly, the multifractal spectrum algorithm is used to extract the feature data of vibration signals, and then the feature data is used as the input vector of support vector machine to realize the fault classification. The experimental data show that the method can accurately identify the common shafting faults, and provide a new method for the intelligent identification of shafting faults of hydropower units. Reference | Related Articles | Metrics

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Research on Longitudinal Magnetron Tungsten Inert Gas Welding Arc Trajectory Behavior CHENG Weirui, TANG Fang, YANG Chengming, LI Xiangwen, SHEN Yaren Hunan Electric Power    2022, 42 (5): 42-47.   DOI: 10.3969/j.issn.1008-0198.2022.05.007 Abstract （130）      PDF（pc） （2590KB）（143）       Knowledge map    Save Tungsten inert gas arc welding(TIG)technology is widely used in recent years,due to its arc stability, good welding quality, small spatter, widely used fields. TIG welding arc behavior is studied by varying magnetic field frequency, magnetic induction and welding current in the paper. The results show that the TIG arc without external magnetic field is conical, the upper part of TIG arc shrinks and the bottom part of TIG arc expands axially when applied longitudinal magnetic field. The arc profile becomes smaller obviously when applied AC longitudinal magnetic field, and there is obvious convergence at the end of arc. Reference | Related Articles | Metrics

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Research on Improvement Scheme of Frequency Emergency Control for New Power System CHU Xu, XU Liqiang, YAN Yabing, LIU Qi Hunan Electric Power    2022, 42 (4): 13-17.   DOI: 10.3969/j.issn.1008-0198.2022.04.003 Abstract （124）      PDF（pc） （2932KB）（142）       Knowledge map    Save Due to the power characteristics of renewable energy units such as wind power and photovoltaics, and the commutation characteristics of inverter power sources such as DC transmission and photovoltaics, the new power system formed has low inertia and low damping. The system frequency changes quickly and the amplitude is large under the power grid big disturbance scenario. Therefore, it is urgent to study the frequency emergency control improvement scheme suitable for new power systems. Based on the analysis of the frequency characteristics of synchronous machines and inverters, this paper proposes a new power system frequency emergency control improvement scheme that considering distribution network activation, energy storage and renewable energy coordination. The algorithm calculates the real-time power direction of the transmission channel between the active distribution network and the main network, realizes frequency regulation according to the difference of power supply and load attributes, and realizes fast and efficient system frequency emergency control according to the regulation characteristics of energy storage and renewable energy. Reference | Related Articles | Metrics