Hunan Electric Power

Transient Characteristic of MOESFET Based on Cosimulation Simulink with COMSOL

GAO Bing, WANG Shuai, ZHONG Yongheng, SUN Yasen, ZHANG Shangchen, ZHOU Jie

2022, 42(5): 1-7. doi:10.3969/j.issn.1008-0198.2022.05.001

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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.

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

2022, 42(5): 8-15. doi:10.3969/j.issn.1008-0198.2022.05.002

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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.

Study on Wind-Proof of Indirect Air Cooling Tower with Vertical Layout

CHEN Yun, WANG Limin

2022, 42(5): 16-21. doi:10.3969/j.issn.1008-0198.2022.05.003

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The air cooling system is greatly affected by the change of external climate. When the wind speed increases or the temperature rises, the heat transfer capacity of the air cooling radiator decreases, thereby leading to the rise of the unit's back pressure. In order to make sure the unit operating safely, some measures should be taken to reduce the influence of high wind speed. In this paper, the flow field distribution and heat dissipation capacity of four models are simulated under high wind speed. According to the analysis and comparison of flow field distribution and heat dissipation capacity data, the heat dissipation capacity of indirect air-cooling tower is as follows: wind-proof wall outside the tower, adjusting shutter, cross wall inside the tower, without any wind-proof measures.

An On-Line Voltage Stability Assessment Method based on Particle Swarm Optimization Support Vector Regression Prediction

LI Shuaihu, ZHAO Xiang , JIANG Yunchen

2022, 42(5): 22-28. doi:10.3969/j.issn.1008-0198.2022.05.004

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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.

Research on Fast Voltage Regulation Control Strategy for Wind Farm Based on GOOSE Communication

GUO Chunling, CAI Guoyang, SHAN Xin, NIU Chao

2022, 42(5): 29-35. doi:10.3969/j.issn.1008-0198.2022.05.005

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In order to solve the problem of insufficient reactive power and voltage support capability of wind power generation, the reactive power and voltage support capability of wind turbine is analyzed firstly based on the characteristics of voltage sag and system impedance, the calculation method of total reactive power demand under voltage disturbance is proposed, finally generic object oriented substation event(GOOSE)rapid communication is introduced to construct the test environment in the wind farm, and the field test is carried out. The experimental results show that the strategy can provide fast reactive power and voltage support, and the response time can be reduced to less than 50 ms.

Diagnosis of Circuit Breaker Current Characteristics Based on LSSA-BP Neural Network

JIA Hao, ZHANG Lian, ZHANG Shangde, ZHAO Mengqi, ZHAO Na, HUANG Wei

2022, 42(5): 36-41. doi:10.3969/j.issn.1008-0198.2022.05.006

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As a device that can widely play a role in security protection in various power system applications, high voltage circuit breaker has great significance for its fault diagnosis research. Aiming at the problems of slow convergence speed and insufficient convergence accuracy of traditional BP neural network, an improved sparrow search algorithm is proposed to optimize the BP neural network. The model obtains more reasonable initial parameters by introducing Logistic chaotic map when the sparrow algorithm initializes the population, and introduces dynamic adaptive weight, Cauchy mutation strategy and reverse learning strategy in position update and optimal solution update respectively, so that the average accuracy of the model for circuit breaker fault classification diagnosis is close to 100%, which indicates that the improved BP neural network has higher accuracy.

Research on Longitudinal Magnetron Tungsten Inert Gas Welding Arc Trajectory Behavior

CHENG Weirui, TANG Fang, YANG Chengming, LI Xiangwen, SHEN Yaren

2022, 42(5): 42-47. doi:10.3969/j.issn.1008-0198.2022.05.007

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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.

Research on Multi-Level Dispatching Coordination Control Strategy and Auxiliary Decision of AC-DC Hybrid Power Grid

TAN Wenzhong, WANG Qisheng, MEI Hongxing, XIE Hao, ZHANG Siyuan

2022, 42(5): 48-52. doi:10.3969/j.issn.1008-0198.2022.05.008

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At present, the new type of AC-DC hybrid power grid urgently needs new dispatching control methods. Based on the static partitioning and online system auxiliary decision-making model, this paper proposes a control method based on the combination of optimal dynamic partitioning and minimum low-voltage load loss. According to the integrated control strategy, the provincial dispatch cost control objective function based on dynamic partition and load shedding coordinated optimization and the regional dispatch low-voltage control objective function based on section sensitivity are respectively constructed, and the specific connotation of the two control levels and coordinated optimization decision-making are clarified. The validity of the proposed model and method is verified by a simulation example.

Application of Distributed Energy Storage in Distribution Networkand Its Economic Evaluation

ZHAO Yuting, LYU Dangzhen, WAN Dai, ZHAO Yongsheng

2022, 42(5): 53-59. doi:10.3969/j.issn.1008-0198.2022.05.009

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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.

Study on Simple Field Test Method of Thyristor Control Performance of SVC

WU Jinbo, HU Dijun, HONG Quan, LI Long, LI Li, CAI Yuhua

2022, 42(5): 60-63. doi:10.3969/j.issn.1008-0198.2022.05.010

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The existing testing methods of thyristor control performance of thyristor controlled reactor branch are cumbersome and complicated, which are not suitable for field operation environment. Aiming at this problem, a simple testing method of static var compensator thyristor control performance is proposed. This method is simple in wiring, and the control performance of static var compensator(SVC) thyristor by using common instruments and equipment on site can be effectively detected, and has high practicability and operability.

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

2022, 42(5): 64-68. doi:10.3969/j.issn.1008-0198.2022.05.011

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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.

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

2022, 42(5): 69-74. doi:10.3969/j.issn.1008-0198.2022.05.012

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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.

Detection Method of Metal Fitting Rust Defects for Overhead Transmission Lines Based on UAV Patrol of Deep Learning

ZHANG Jiasheng, LIANG Jinxing

2022, 42(5): 75-78. doi:10.3969/j.issn.1008-0198.2022.05.013

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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 A_P 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.

Design and Implementation of Automatic Inspection Tool for Power Optical Transmission System

ZENG Xiaohui, CHEN Xiaohui, ZHU Qing, LI Mingjuan, DU Mu′en

2022, 42(5): 79-84. doi:10.3969/j.issn.1008-0198.2022.05.014

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The optical transmission system is the carrier of the power service channel, and the current post-event passive fault repair operation and maintenance mode is not enough to meet the needs of the operation and maintenance work, while the traditional proactive hidden danger prevention mode is mainly manual periodic inspection, in which the optical path performance inspection needs a lot of manpower. In this paper, the abundant northbound interface of the dedicated network management is used to collect data, design the complete optical section object and the abnormal optical path judgment algorithm, develop the automatic inspection tool of the power optical transmission system, automatically output the inspection results, and give an early warning to the abnormal optical path, so as to find hidden dangers in time to avoid the occurrence of faults and improve the level of independent operation and maintenance.

Auxiliary Judgment Method of Single Phase Grounding Fault in Distribution Network Based on Distribution Automation System

LUO Xuelian, CHEN Chenggong, LIU Zhihao, ZENG Huanyue

2022, 42(5): 85-89. doi:10.3969/j.issn.1008-0198.2022.05.015

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Aiming at the problems of high cost, low line selection efficiency and low success rate of grounding line selection device in distribution network, based on the steady state zero sequence quantity of distribution automation master station system, a grounding fault auxiliary judgment module based on zero sequence impedance comparison and historical data reference is developed. Firstly, the electrical characteristics of 10 kV distribution network under single phase grounding fault are analyzed in detail, and a grounding line selection method is obtained according to the principle of zero sequence impedance comparison. Secondly, through the statistics of historical grounding data, the probability of grounding fault in distribution network lines is calculated, and the historical fault quantity, important degree mark quantity and zero sequence current are weighted by entropy method, so as to form an auxiliary judgment module of single phase grounding fault in distribution network relying on distribution automation system. Finally, the case analysis shows that this module has high accuracy in line selection.

Measures of Performance Optimization and Improvement of Three-Phase Inconsistent Protection for Circuit Breaker

GUO Yang, CHEN Hao, GAO Shiyu, GU Hao, LI Yifeng

2022, 42(5): 90-94. doi:10.3969/j.issn.1008-0198.2022.05.016

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Based on the typical secondary circuit, this paper introduces the principle of three-phase inconsistent protection in high-voltage power system, analyzes the causes of protection maloperation from the aspects of circuit insulation fault, artificial factors, improper setting of pressure plate and so on, and puts forword the optimization and improvement measures. The application practice shows that the optimized measures are feasible and effective, and the performance of three-phase inconsistent protection is greatly improved.

Application of Steam Temperature Control Technology of Wide Load Peak Shaving for Thermal Power Unit

WANG Xihui, ZHU Xiaoxing, CHEN Houtao, ZHOU Ke, ZHU Guangming, SHENG Kai , TAO Hailin

2022, 42(5): 95-100. doi:10.3969/j.issn.1008-0198.2022.05.017

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The steam temperature control method is put forword,and an improved PID control algorithm is designed in the cooling water control circuit, and a modified instruction with self-learning function is introduced to adjust the parameters. In the coordinated control loop, a coordinated control algorithm based on running state analysis and humanoid modification is designed. In practical application, the steam temperature of a 630 MW supercritical unit is well controlled in wet stable operation and variable load operation, dry stable operation and variable load operation under 28.7%~100% rated load interval, the control quality of some working conditions has improved more than 60% compared with the industry standard. When a 1 000 MW ultra-supercritical unit is running in 30%~100% rated load range, the steady state control quality of steam temperature is improved 30%~60% compared with the industry standard.

Control Technology of Ammonium Bisulphate In Denitrification of SCR Flue Gas after Ultra-Low Emission Transformation of Coal-Fired Unit

ZHAO Guangyao, HUANG Quanhao, ZHU Yingjian, DU Shengxiang

2022, 42(5): 101-106. doi:10.3969/j.issn.1008-0198.2022.05.018

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This paper introduces the mechanism of ammonium bisulfate generation, points out the harm of ammonium bisulfate to boiler equipment, analyzes the influencing factors of ammonium bisulfate generation, studies the harm of ammonium bisulfate to boiler equipment after ultra-low emission transformation, and puts forward specific methods to control the amount of ammonium bisulfate generation according to its characteristics.

Research and Application of Grid Structure Comparison Index of Transmission Network in Urban Central Area

LI Jiani, TAO Telun, WANG Yuan, LUO Shiwei, WU Qian, ZHOU Kangjun, XU Hui

2022, 42(5): 107-113. doi:10.3969/j.issn.1008-0198.2022.05.019

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This paper establishes the index of transmission network structure selection, which covers the large-scale clean energy consumption, the comprehensive risk and the total cost of the power network, and presents the selection process and the results of 500 kV HG station network structure selection in the city center. The results show that the evaluation method and index can adapt to all kinds of constraints, and the input parameters can be easily obtained. This index considers both normal operation and serious failure, and also economy, which can effectively cover the main issues of concern to decision-makers.

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

2022, 42(5): 114-118. doi:10.3969/j.issn.1008-0198.2022.05.020

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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.

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

2022, 42(5): 119-122. doi:10.3969/j.issn.1008-0198.2022.05.021

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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.

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