Table of Content

25 October 2024, Volume 44 Issue 5

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Invited Column:Electric Power Disaster Prevention and Reduction

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Current Status and Prospects of Hydrodynamic Research in Coal-Fired Boiler Power Plants

QIN Yue, LI Debo, QIN Wu, ZHENG Haoyi, YU Fengjian

2024, 44(5):  1-8.  doi:10.3969/j.issn.1008-0198.2024.05.001

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A study is conducted on the dynamic characteristics of tube wall superheated water in response to the phenomenon of overheating on the heating surface of coal-fired power plant boilers.Through research, it has been found that inaccurate thermal calculations,improper selection of burners,unreasonable arrange‍ment of heating surfaces, and insufficient temperature control conditions ultimately lead to overheating of the boiler heating surface due to thermal deviation oxidation. Through hydrodynamic calcula‍tions, a wall temperature distribution model is established to reveal the fundamental cause of overheating and tube bursting on the heating surface, providing a detailed theoretical basis for analyzing wall temperature changes and developing measurement methods.

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Analysis of the Impact of Uncooled Infrared Detectors in Wildfire Detection Applications

OUYANG Yi, ZHANG Huayu, WU Wenli, SHEN Jiabin

2024, 44(5):  9-16.  doi:10.3969/j.issn.1008-0198.2024.05.002

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In response to the lack of quantitative analysis on the fire detection capability and spatial reliabil‍ity of spaceborne infrareduncooled systems in existing research, which limits the development of wildfire monitoring satellites, the infrared remote sensing imaging principle is utilized to systematically compare the fire detection capabilities of spaceborne infrared non cooling and cooling systems through theoretical derivation and ground combustion experiments, while analyzing the reliability of uncooledspace.The results indicate that both uncooled and cooled infrared detectors can detect sub-pixel targets with a temperature of 473 K occupying at least 1/9 of a pixel in blackbody radiation. In the case of real burning materials, both types can detect wildfire targets that occupy 1/36 of a pixel, with the minimum signal‍‍‍-to-clutter ratiofor wood being 14dB.For a small wildfire satellite operating at an altitude of 500 km with a resolution of 60 meters, the spaceborne uncooled infrared detector is capable of detecting small area wildfires on the order of 10 meters.Additionally, results from spatial thermal experiments demonstrate that maintaining temperature control within 1 ℃ on orbit allows uncooled detectors to maintain good spatial reliability. This provides valuable scientific guidance for constructing low earth orbit infrared satellite constellations for wildfire detection, ultimately improving the spatiotemporal accuracy of monitoring wildfires along transmis‍sion lines and ensuring the stable and safe operation of the power grid.

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Research on Thermal Runaway Behavior of Blade Energy Storage Lithium Batteries Based on Acoustic Detection Technology

XU Song, WAN Tao, LI Xin, WU Junjie, ZHA Fanglin, WEI Jiaqiang, CAI Yufeng, LIU Yiyi

2024, 44(5):  17-23.  doi:10.3969/j.issn.1008-0198.2024.05.003

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With the large-scale application of electrochemical energy storage, thermal runaway detection and timely warning research of lithium battery is of great significance for ensuring the safe operation of energy storage power station. In this paper, a test platform for the thermal runaway performance of lithium battery is set up. The sound signal of blade energy storage lithium battery under thermal runaway condition is tested. The acoustic characteristics and change rules of different development stages of thermal runaway such as battery bulging, pressure relief valve opening, venting, explosion and fire are analyzed. It shows the effectiveness of sound feature for thermal runaway detection. Aiming at the problem that the sound characteristics of thermal runaway are easily disturbed by the noise of other equipment such as ventilation fans and PCS in the energy storage battery compartment, an anti-interference analysis method of thermal runaway sound signal based on wavelet packet decomposition and spectral subtraction speech enhancement is proposed. The analysis result shows that the proposed method can effectively eliminate the wind noise interference from the thermal runaway sound signal, and can accurately restore the battery thermal runaway sound characteristics. After denoising, the correlation coefficient between the original and the denoised sound signals reaches 0.96. The results can provide as technical reference for thermal runaway detection and early warning of the energy storage lithium battery.

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Research on Ice-shedding Jumping Characteristics for Overhead Transmission Lines in Micro-Terrain Areas

YANG Junwu, HE Tianpu, LI Zheng, YAO Pu, LI Mei

2024, 44(5):  24-28.  doi:10.3969/j.issn.1008-0198.2024.05.004

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This paper studies the ice-shedding jumping characteristics and typical ice-shedding modes of overhead transmission lines in micro-terrain areas,based on the data from ice-shedding jumping faults that occurred during rainy, snowy, and freezing weather in a certain area of the central China power grid in recent years. At the same time, a new anti ice-shedding jumping control strategy is proposed to solve the problem that ice-shedding jumping faults of transmission line is easy to occur in micro-terrain areas.The strategy takes the high voltage end fixed connection fittings, insulation spacers and fixed cables as the core. The high voltage end of the insulation spacer is connected to the wire through the high voltage end fixed connection fittings, and the low voltage end of the insulation spacer is connected to the fixed cable through the con‍nec‍tion fittings. The near ground end of the fixed cable is forcibly fixed to the ground. By reasonably distributing the installation positions, it can effectively suppress the ice-shedding jumping amplitude of the transmission lines. The feasibility and efficiency of this strategy are evaluated through experimental analysis.

Researches and Tests

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Improved Three-Vector Model-Free Predictive Current Control Strategy Based on Time Series for PMSM Drives

XIAO Qianghui, ZHANG Yushuang, LUO Zhaoxu, CHENG Zhun

2024, 44(5):  29-36.  doi:10.3969/j.issn.1008-0198.2024.05.005

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Aiming at the issue of poor parameter robustness of the conventional three‍-‍vector model predic‍tive current control strategy for permanent magnet synchronous motor drive systems, an improved three-vector model-free predictive current control strategy based on time series is proposed to eliminate the effect of parameter mismatch and enhance the robustness of the system. To begin with, a time-series data‍-driven model is established to fit the input-output data as a discrete transfer function and combined with the recursive least squares method to estimate the model undetermined coefficients online and predict the required variables. In addition, the vector sector is reclassified to optimize the selection process of the three-vector combination. Moreover, the vector duty cycle direct calculation method is introduced to suppress the uncertainty effect of motor parameter ingress on the duty cycle calculation link, which further improves the system robustness. Finally, the simulation and experimental results show that the proposed strategy can ef‍fectively improve the model parameter robustness. The dq-axis current ripple is reduced, and the disturbances caused by the variation of motor parameters can be effectively suppressed.

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Spatial Electric Field Distribution Characteristics of Insulator Strings in High-Voltage Overhead Transmission Lines With Zero Value Insulators

LI Yaoqin, HUO Feng, NAN Jing, LIU Qin, ZHANG Tianyu

2024, 44(5):  37-44.  doi:10.3969/j.issn.1008-0198.2024.05.006

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This article uses finite element simulation calculation method to study the electric field distribu‍tion characteristics when zero value insulators appear in different insulator string types of 110 kV and 220 kV, and compares the sensitivity of composite field strength and axial field strength to zero value insula‍tors. The influence of zero value insulators on different string types is analyzed for single I suspension string, double II suspension string, and tension string.In addition, the influence of zero value insulator position and number on field strength distribution characteristics is quantitatively analyzed. The results show that the axial field strength is more sensitive to the occurrence of zero value insulators, and it is more suitable as a characteristic quantity for detecting zero value insulators. The presence of zero value insulators on the high-voltage side has the greatest impact on the electric field distribution. For the suspension double II string, the field strength on both sides should be measured separately to determine the location of zero value insulators. The decrease in field strength for two and three consecutive zero values is twice and 2.3 times that of a single zero valuerespectively.

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Verification of Low Noise Unmanned Aerial Vehicle Rotor Noise Reduction in Power Inspection Applications

LI Chengwei, LU Ling, DUAN Xinyu, XIE Yi, CAO Hao, WANG Lanbo, MA Wei

2024, 44(5):  45-49.  doi:10.3969/j.issn.1008-0198.2024.05.007

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Unmanned aerial vehicles (UAVs） are widely used in power line inspection tasks due to their ef‍ficiency and flexibility. However, noise remains a critical challenge that needs to be addressed. This study employs beamforming technology to perform noise source localization and validate the noise reduction performance of a low-noise toroidal structure propeller. Through noise spectrum analysis and a virtual rotating array beamforming algorithm based on a microphone array, the noise of the toroidal propeller is compared with that of three other common propellers. Experimental results show that the toroidal propeller exhibits significant noise reduction in both broadband and tonal noise. Beamforming analysis further reveals that the primary noise source of common propellers originates from tips, while the toroidal design effectively mitigates tip noise, achieving noise reduction.

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Research on Grid-Connected Current Active Damping Method Based on Negative Second-Order Generalized Integral Quadrature Signal Generator Feedback

CHEN Gang, LIU Yaxiong, LI Guoxiong, LIU Xuyang

2024, 44(5):  50-56.  doi:10.3969/j.issn.1008-0198.2024.05.008

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The realization of active damping for the feedback state variables of the LCL filter requires high precision sensors to have better flexibility and robustness. Therefore, this paper proposes an active damping method of grid-connected current fed back by negative second-order generalized integral quadrature signal generator. While suppressing the resonance peak, it also reduces the influence of grid-side voltage back‍ground harmonics on grid-connected current, and reduces the number of sensors to increase system re‍liability. The parameters of negative second-order generalized integral orthogonal signal generator are de‍signed around the stability margin of the system by pole assignment method. Then, the robustness of the system is discussed when the LCL parameters and grid impedance change under the active damping control system . The simulation results show that the proposed strategy has better effect in all aspects.

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Theoretical Study on Health Index Based on Provincial Power Grid Operation Data

LIU Yuming, QIAN Jun, CHEN Bin, YANG Bo, ZHANG Jingfan, MEI Hongxing

2024, 44(5):  57-61.  doi:10.3969/j.issn.1008-0198.2024.05.009

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The paper proposes a health index theory based on provincial grid operation data regarding the current operational status of the power grid system.Based on the importance of ensuring energy supply,starting from the two dimensions of safety and reliability and the importance of energy supply, the paper proposes five indexes including load transfer rate, equipment fault ratio, reclosing success rate, fault recovery time, and fault voltage level coefficient. In order to ensure the reasonableness of index weight calculation, the subjective weight, objective weight and comprehensive weight are obtained by game theory method. By analyzing and calculating the tripping data of 14 municipalities in Hunan, the health index levels of different municipalities are given. Finally, the paper measures the health index level of the grid in a local city throughout the year and analyzes the correlation between its health index changes and weather, and provides guidance suggestions for the actual operation of the grid.

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Power System Economic Load Dispatch Based on Improved Artificial Bee Colony Algorithm

ZHAO Wanyun, YOU Rui

2024, 44(5):  62-67.  doi:10.3969/j.issn.1008-0198.2024.05.010

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The traditional intelligent algorithms usually have slow convergence speed and poor optimization capability while dealing with the discontinuous,non-convex and nonlinear power system economic load dispatch problems.A new algorithm combined simplex search method with artificial bee colony algorithm is proposed and applied to power system economic load dispatch problems.This algorithm maintains the powerful global search capability of artificial bee colony algorithm and improves the search mode of onlooker.In addition, it uses the simplex search method to optimize better food sources provided by the artificial bee colony algorithm quickly and determinately.So,it improvs the search capability and convergence speed of the new algorithm. Moreover,an effective repair procedure is proposed to guarantee the feasibility of the new individuals.Experiments are carried out on some power system economic load dispatch problems with valve-point effects. Simulation results show the effectiveness of the proposed algorithm.

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Intelligent Identification Method for Power Internet of Things Terminals Based on Business Baseline

LI Mingguang, YANG Fangliao, LI Haozhi, HUANG Xin, YANG Shenghong

2024, 44(5):  68-73.  doi:10.3969/j.issn.1008-0198.2024.05.011

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Aiming at the key link of the digital construction of the new power system, a smart identification method for power internet of things（IoT）terminals based on business baselines is proposed. The method collects flow messages from power IoT terminals, analyzes data distribution characteristics, and defines the business baseline of power IoT terminals. The feature vectors from the terminal devices that need to be identified are extracted, matching them with the business baseline, so as to achieve intelligent identification of power IoT terminal devices that communicate using Modbus RTU protocol. To verify the effectiveness of the method, 10 types of power internet of things terminal devices are collected to receive autonomously constructed Modbus message frames continuously 10 times per unit time, and corresponding response data are returned. The results show that when the threshold is higher than 0.08, the recognition accuracy is high, and the proposed method does not require complex feature extraction, and the recognition accuracy is high.

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Identification of Characteristic Parameters of Material Magnetic Property Model and Analysis of Transformer Vibration Characteristics Based on GA-LM Algorithm

GUO Chun, HUANG Feng, LI Yu, LI Xuxin, ZHANG Renjie

2024, 44(5):  74-80.  doi:10.3969/j.issn.1008-0198.2024.05.012

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A vibration calculation method for oil immersed transformers based on multi physics coupling is proposed to address the issue of safe and stable operation. Firstly, a model is established based on the classical J-A hysteresis theory, and parameter identification is carried out by combining experimental measurement data. The genetic least squares optimization algorithm is used to obtain the characteristic parameters of the model. On this basis, based on finite element simulation software, an electromagnetic structural multi physics field coupling model is established, and the identified characteristic parameters are introduced into the model for calculation. The magnetic field distribution and vibration displacement distribution of the oil immersed transformer under normal operating conditions are calculated, providing a basis for accurate calculation of the vibration of the oil immersed transformer.

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Electromagnetic Wave Propagation Characteristics Analysis in Partial Discharge of Cable Joint and Sensor Optimation Design of Sensor

ZHOU Xuehuan, ZENG Ping, LIU Zhigang, CHEN Qian, CHENG An, ZHANG Zequan, CAI Xinjing

2024, 44(5):  81-86.  doi:10.3969/j.issn.1008-0198.2024.05.013

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In response to the low detection sensitivity of high-frequency current method for detecting partial discharge faults in cable intermediate joints, based on the high sensitivity of capacitive coupling method, finite element method is used to simulate the electromagnetic wave propagation characteristics of partial discharge in cable intermediate joints. The variation law of electric field intensity in three directions at dif‍ferent monitoring points is obtained. At the same time, the attenuation characteristics and spectral characteristics of partial discharge electromagnetic waves are analyzed, and the capacitance sensor is optimized for design, providing reference for the application of capacitance sensors in monitoring partial discharge in cable intermediate joints.

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Photovoltaic Output Prediction Without Surface Irradiance Based on Weighted Similarity Meteorological Search

YANG Jiahao, ZHANG Lian, WANG Shibin, LI Heng, XIAO Yuanqiang

2024, 44(5):  87-94.  doi:10.3969/j.issn.1008-0198.2024.05.014

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Aiming at the problem lacking of surface solar radiation(SSR） data when forecasting the photovoltaic(PV） power generation, a PV power generation forecast method without SSR information is proposed. First, the astronomical radiation feature is added on the original data. Considering that this feature may still not meet the prediction accuracy requirements, output data under similar meteorological data is introduced as another augmented feature. Second, the method of feature weighting is proposed for the similarity algorithm, and the weight coefficients of each feature are obtained by the synthetic scoring of three scoring methods of Spearman, maximum information coefficient, and the importance of random forest features through the D-S evidence theory, so as to extract the meteorological data and further improve the ac‍curacy of the similarity algorithm. Finally, the similar day search results and similar hour search results under Euclidean distance and cosine similarity methods are compared. The study of a PV power plant in Ningxia shows that the weighted Euclidean distance similar hour search results obtain the optimal forecast performance, that the average accuracy rate and qualification rate of the four seasons reaches 0.889 and 0.944 respectively, promising a relatively good forecast result of PV output without the SSR information.

Experience and Discussion

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Research on Distribution Substation Voltage Regulation Strategy Based on Photovoltaic Inverter Power Control

LIU Hongzheng, ZUO Yi, WANG Lun, HUANG Qiaoyu

2024, 44(5):  95-101.  doi:10.3969/j.issn.1008-0198.2024.05.015

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Due to the regularity of photovoltaic output, there is a phenomenon of high and low voltage cross‍ing and interweaving in the distribution substation area after photovoltaic integration, which seriously affects the safe and reliable operation of the distribution network. To address the issue of high and low voltage crossing caused by photovoltaic integration, the paper analyzes the mechanism of voltage crossing in the distribution network substation area, and studies the dual closed-loop control and active and reactive power output characteristics of photovoltaic inverters. On this basis, a voltage regulation strategy for the distribution transformer substation area based on photovoltaic inverter power control is proposed to achieve a reasonable range of terminal distribution transformer substation area voltage under different operating conditions. The effectiveness of the control strategy is verified through simulation.

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Transregional Interconnection Hyperconverged Power Communication Network Management System

REN Xiaolin, SUN Yong, SONG Fuyong, FANG Bo, HUANG Hualin, LI Chunsheng, HU Liwen

2024, 44(5):  102-108.  doi:10.3969/j.issn.1008-0198.2024.05.016

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Regarding the management of cross regional interconnected hyper converged power com‍munica‍tion networks,and starting from the monitoring and control functions of power communication networks, combined with the universality of network element equipment access, broadband carrying capacity, and information security characteristics, this paper analyzes the carrying requirements of power communication networks for network element equipment. Finally, taking communication network element equipment as an example, a power communication network management system is built, and key indicators such as latency characteristics of the network management system are simulated. The experimental results show that the system in this article can effectively identify the operating status of power equipment, especially faulty equip‍ment, which has reference significance for further realizing the integration and management of different networks.

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Short‍-Term Load Forecasting Method for Regional Power Grid Based on Segmented Prediction and Weather Similar Day Selection

LIANG Haiwei, WANG Yangguang, DENG Xiaoliang, LIU Jing, WEN Ming, YU Zongchao, LI Wenying

2024, 44(5):  109-116.  doi:10.3969/j.issn.1008-0198.2024.05.017

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In order to improve the accuracy of load forecasting for the four key periods of power grid operation, namely low valley load, noon peak load, waist load load, and evening peak load, a short-term load forecasting method based on segmented forecasting and weather similar day selection is proposed. Firstly, the paper analyzes the impact of different factors, including meteorological and economic factors, on the load of the regional power grid at different time periods, and select relevant features as the training set for construction.Secondly, the paper adopts a long short term memory neural network model to achieve load forecasting for different time periods. Using mutual information and Euclidean distance, the paper selects similar days with weather conditions close to the day to be predicted, and uses the load curve of that day as a reference,combining with the segmented load forecasting results as the load forecasting result for the day to be predicted. The experimental results show that the proposed short-term load forecasting method can ef‍fectively improve the accuracy of short-term load forecasting, especially for low valley, noon peak, waist load, and evening peak periods, with a significant improvement in prediction accuracy.

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A Method of Wind Farms Limit Capacity Increase Considering Influence of Environmental Temperature and Wind Speed

HE Guangling, QU Junhui, YE Shishun, FAN Qiumin, WANG Tong, FANG Qilin

2024, 44(5):  117-123.  doi:10.3969/j.issn.1008-0198.2024.05.018

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At present, only the influence of wind speed is considered in the calculation of the transmission capacity of wind farms, and the influence of ambient temperature is not considered.In the analysis of the ultimate current carrying capacity of overhead conductors,the special working environment of wind power is not considered, resulting in the waste of wind farm line transmission resources. Therefore, this paper proposes a method to increase the capacity of wind farms considering the influence of ambient temperature and wind speed to maximize the development and utilization of wind power resources. Firstly, the influence of ambient temperature is added on the basis of the traditional turbine output model, and the turbine output model is improved. Then, through the overhead conductor thermal balance equation, the ultimate current-carrying model of the conductor considering the combined influence of ambient temperature and wind speed is established. Finally, by drawing the distribution of the total output surface of the wind turbine and the ultimate current-carrying surface of the conductor in the coordinate system of ambient temperature and wind speed, the output of the wind turbine is matched with the limiting current-carrying characteristics of the conductor to obtain the maximum allowable output capacity of the wind farm. The simulation results show that the wind power transmission line with the same conductor cross-section has a certain transmission power margin, and the paper method can determine the ultimate transmission capacity of the wind farm and improve the economic benefits of the wind farm, which is of great significance for guiding the capacity increase of the wind farm.

Faults and Analysis

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Mechanical Failure Diagnosis Method for High-Voltage Circuit Breakers Based on Vibration Signal Analysis

MA Zhaoxing, LIU Jinxin, LI Ji, WANG Jing, CHEN Hao, JI Haomin, WANG Ruihua

2024, 44(5):  124-130.  doi:10.3969/j.issn.1008-0198.2024.05.019

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By analyzing the vibration signals of high voltage circuit breakers（HVCB）, fault types can be identified based on their different vibration characteristics. Using an improved wavelet threshold denoising method for data preprocessing of circuit breaker vibration signals, and extracting the energy proportion of each frequency band through wavelet packet transform, HVCB fault diagnosis is achieved based on the analysis of energy distribution characteristics. Engineering examples show that the method proposed in this paper can effectively achieve mechanical fault diagnosis of HVCB, providing a new technological means for intelligent operation and inspection of high-voltage circuit breakers.

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CatBoost-SHAP Transformer Fault Diagnosis Study for Unbalanced Data

LIANG Fazheng, ZHANG Lian, YANG Jiahao, YANG Yujie, LI Heng, XIAO Yuanqiang

2024, 44(5):  131-138.  doi:10.3969/j.issn.1008-0198.2024.05.020

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A transformer fault diagnostic method based on Borderline-SMOTE-CatBoost-SHAP is proposed for the problem of degradation of classification performance of fault diagnostic model and uninterpretable model diagnostic results caused by unbalanced distribution of transformer fault data. Firstly, the Borderline-SMOTE algorithm is used to equalize the data while retaining the distribution characteristics of a few classes of samples, solving the bias problem caused by the imbalance of fault data distribution. And then, the CatBoost transformer fault diagnosis model is constructed, and simulation experiments are carried out by us‍ing the actual fault data of the transformer to compare it with different data equalization methods and other transformer fault diagnosis models. Finally, the SHAP model is introduced to provide a more accurate and reliable classification model for transformer fault diagnosis. The SHAP model is introduced to analyze the interpretability of the CatBoost fault diagnosis model to solve the problem of poor interpretability of the “black box model”. The result shows that the overall diagnostic accuracy of the transformer fault diagnosis model based on Borderline-SMOTE-CatBoost-SHAP is 92.99%, the F₁ value is 0.91, and the Kappa coef‍ficient is 0.91. Meanwhile, the process of input features for decision-making is visualized to verify the validity of the proposed method.