Table of Content

30 October 2022, Volume 0 Issue 10

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Overview

Research Status of Fault Diagnosis Methods for On-Load Tap Changer

SONG Dongdong, ZHAO Bo, MA Yuquan, WANG Qingzhu, GENG Lijun, ZHAO Jianping

2022, 0(10):  1-8.  doi:10.16628/j.cnki.2095-8188.2022.10.001

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On-load tap changer (OLTC) is an important component of on load voltage regulating transformer.During operation,the contact switches frequently and the current is large,and faults occur frequently.Frequent troubleshooting requires off grid operation,which results in large economic losses and affects the normal operation of the power grid.The existing OLTC signal analysis methods are summarized and compared.According to the real-time monitoring method,it can be divided into intervention and non intervention testing.According to the test parameters,it can be divided into electrical signal and non electrical signal tests.The method of multi dimension parameter and multi strategy detection has better recognition accuracy.Subsequently,the fault diagnosis expert database system or machine learning can be used to better realize OLTC condition monitoring and fault diagnosis.

Research & Analysis

Consistent Robust Design of Bistable Crystal Cover Relay

LIU Guilin, WEI Zitong, LIANG Huimin, ZHANG Jie, ZHANG Jingbo

2022, 0(10):  9-16.  doi:10.16628/j.cnki.2095-8188.2022.10.002

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The bistable crystal cover relay has outstanding adaptability to the endurance environment,but there are the quality problems such as small debugging margin and large product dispersion,which is difficult to meet the requirements of continuously improving reliability indicators of electronic systems.Aiming at the problems such as poor anti-interference of output characteristics caused by the imperfect reliability design theory of relays at present,the simulation model of relay electromagnetic system and contact spring system is established.The robust design method proposed by Taguchi Genichi is used to optimize the relay product parameters and their tolerances in order to improve their reliability.The research conclusions are applied to the improvement of a certain type of electromagnetic relay,and its related methods can be applied to the design of other electrical products,which can provide the necessary research methods and foundations for the robust design of electromagnetic relays.

Research on TM Control Method of UCC28065 Based on Interleaved Boost PFC

CHEN Xinwei, LIN Weiming, JING Huafeng

2022, 0(10):  17-24.  doi:10.16628/j.cnki.2095-8188.2022.10.003

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In order to improve the power level of the front stage boost PFC circuit,with lower input current ripple,smaller volume of input EMI filter,and better overall performance,an interleaved boost PFC circuit based on UCC28065 is proposed.The operating principle,operating process and TM control method of the circuit are analyzed in detail.The key parameters of the main circuit,control circuit and closed-loop compensation network are analysed and designed.Finally,the simulation is carried out and a 600 W experimental prototype is built up for verification.The experimental results show that the soft switching is realized,efficiency is improved to 96.35%,the power level is improved,and PFC performance have been obtained to verify the proposed control method.

Evaluation Index System Research on Carrying Capacity in Active Distribution Network Under Background of Regional Energy Internet

FEI Ke, WANG Xiaodong, SHA Yucheng, XU Chao, GUO Hao, MA Yongzhen

2022, 0(10):  25-31.  doi:10.16628/j.cnki.2095-8188.2022.10.004

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With the massive multi power and load connect to distributed network,an active distribution network for the energy interconnection is formed.In order to evaluate the adaptability of distribution network to multi power and load,an evaluation method for the carrying capacity of active distribution network oriented to the regional energy internet is proposed.Firstly,the level of power supply capacity,power quality and network loss which are caused by the distributed generation connect to active distributed network is analyzed.Secondly,the evaluation index system of the active distribution network carrying capacity based on 18 underlying indicators is established.Then,the entropy weight method is proposed to calculate index weight.Finally,taking the module of IEEE 33,the carrying capacity of active distribution network is calculated,which can provide the scientific reference advice and suggestion for distribution network planning,construction and operation control.

Partial Discharge Pattern Recognition Based on Convolutional Neural Network and UHF Technology

SUN Tianlong

2022, 0(10):  32-37.  doi:10.16628/j.cnki.2095-8188.2022.10.005

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Partial discharge is one of the main factors that lead to the deterioration of the insulation performance of power equipment and eventually lead to insulation failure.The traditional method of detecting partial discharge of equipment is complicated,requires regular manual inspection,and cannot monitor the insulation status of equipment in real time.When partial discharge occurs,high-frequency electromagnetic wave signals will be radiated outward.An online monitoring of partial discharge based on UHF technology and a method for constructing a phase resolved partial discharge (PRPD) map is proposed.This method is used to obtain the amplitude and time information of partial discharge pulses to construct a PRPD map,and the PRPD map is gridded to obtain a grayscale image of 36×30 size.Finally,the optimized convoluntional neural network model is used to identify the four typical discharge types.

An Artificial Intelligence Image Recognition Method Suitable for Intelligent Inspection of Transmission Line

RAO Chengcheng, LUO Liyi, XU Jianer

2022, 0(10):  38-43.  doi:10.16628/j.cnki.2095-8188.2022.10.006

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Feature extraction is one of the most important stages of processing aerial patrol images of transmission lines.The recognition accuracy of fault or target by the traditional methods is not high,single,time-consuming,and easy to be affected by the factors such as background,shape and material,so it is difficult to be applied in practice.In order to solve the defects of the above traditional methods,the deep learning is introduced,a region based full convolution network is adopted.The network is trained with labeled data,and the improved methods such as online difficult sample mining,sample optimization and soft non maximum suppression are used for optimization.The experimental results show that the proposed aspects are faster and more accurate in locating targets.The detection accuracy applied in transmission line patrol inspection is high,so as to meet the needs of transmission line intelligent patrol inspection.

Electrical Design & Discussion

Influence of Current Conditioning Process Parameters on Contact Surface Morphology in Vacuum Interrupter

XUE Feng, LI Min, LIN Liangwei, LIAO Qing

2022, 0(10):  44-47.  doi:10.16628/j.cnki.2095-8188.2022.10.007

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In view of the influence of DC high current conditioning parameters on VI contact conditioning performance,the conditioning energy,contact stroke,synchronization between contact opening and capacitor discharge,arc injection mode and conditioning times on the coverage rate of vacuum arc abulation on contact surface are mainly studied.The results show that increasing conditioning energy,increasing contact stroke,adding low current striking arc and increasing conditioning times can improve contact conditioning effect.

Contact Characteristics Analysis and Optimization of Connector

QI Xiaojun, FENG Weijie

2022, 0(10):  48-55.  doi:10.16628/j.cnki.2095-8188.2022.10.008

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Aiming at the problem of fracture of the connector caused by excessive local stress in the AC contactor,the orthogonal test method is adopted to optimize the structure of the connector.By the method of orthogonal test,the influence of different structural sizes of connector on the insertion force of the insert terminal,the clamping force of the connector and the equivalent stress of the connector are studied.So the test is carried out for the simulation results.In order to solve the problem of low efficiency of contact analysis,an efficient algorithm of equal replacement is proposed to simplify the nonlinear contact calculation in the process of inserting terminals into connector.Compared with the conventional nonlinear contact algorithm,the calculation accuracy of the two algorithms is equivalent,but the calculation efficiency of the proposed algorithm is increased by 87.5%.After the optimization,the insertion force of the terminal is reduced by 71%,and the maximum equivalent stress is reduced by 75%,which can improve the service life of the connector.

Simulation and Experimental Research on Parallel IGCT of DC Circuit Breaker

LIU Xiaoyang, ZHOU Liu

2022, 0(10):  56-61.  doi:10.16628/j.cnki.2095-8188.2022.10.009

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The power electronic components including IGCT are connected in parallel at both ends of the conventional current injection DC circuit breaker,and the components are used to realize the tasks of breaking the rated current,shunting the short-circuit current and freewheeling in the commutation process,which can reduce the breaking pressure of the fast vacuum circuit breaker.Aiming at the reverse current condition of the IGCT during the short-circuit current breaking process,the influence of the stray inductance of the freewheeling branch of the auti parallel diode assembly on IGCT reverse current is analyzed.On this basis,an improved scheme to reduce the stray inductance of the auti-parallel diode freewheeling branch is proposed.Through simulation and experiment,it is verified that the improved scheme can effectively eliminate the reverse current phenomenon of IGCT,which can improve the reliability of IGCT application and the feasibility of practical engineering application.

Optimal Designof Operating Mechanism of Miniature Circuit Breaker

HUANG Jia, SHI Keshao, ZHAO Ming, SHENG Yongbing, ZHANG Yanyang, REN Changbin

2022, 0(10):  62-64.  doi:10.16628/j.cnki.2095-8188.2022.10.010

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For the operating mechanism of miniature circuit breaker,the size of the four connecting rods of the operating mechanism is adjusted through the mechanism diagram to increase the total travel of the operating mechanism.Under the condition of maintaining the required final contact pressure,the key dimensions of the parts in the operating mechanism are inversely deduced by theoretical calculation combined with static analysis.Then,according to the theoretical calculation parameters,the part is opened to verify the feasibility of the scheme.The proposed method can provide the design direction for the structural optimization of miniature circuit breakers.

Detection & Experiment

DC Series Fault Arc Detection Method Based on SSA-ELM

LIU Shuxin, LIU Xueshi, LI Jing, CAO Yundong, LIU Yang

2022, 0(10):  65-73.  doi:10.16628/j.cnki.2095-8188.2022.10.011

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To solve the problem of the randomness and instability of fault arc signal,a DC series arc fault detection method based on sparrow search algorithm extreme learning machine (SSA-ELM) is proposed.Firstly,the experimental platform is built according to UL 1699B standard for data collection.Secondly,the DC arc fault signal is decomposed into the intrinsic mode components (IMF) by the complete ensemble empirical mode decomposition with adaptive noise(CEEMDAN).On the basis of the correlation coefficient and energy distribution of each IMF,the sample entropy as the feature quantity is extracted.Finally,SSA-ELM is used to learn the feature quantity,and the model is used for DC series arc fault detection.The experimental results show that CEEMDAN method is not sensitive to signal interference,SSA-ELM has a fast learning speed and is more accurate and sensitive for DC series arc fault detection and recognition.

Research on Time Parameter Detection System of HV Circuit Breaker Based on Current Signal

JIANG Jun, ZHENG Xiang, ZHU Ningning

2022, 0(10):  74-77.  doi:10.16628/j.cnki.2095-8188.2022.10.012

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Aiming at the time parameter detection of HV circuit breaker,a detection method is proposed.According to the characteristics of the coil current during the circuit breaker operation,the compensation Hall current sensor is selected,and the coil current signal is collected by FPGA.Then the current signal with noise is denoised by wavelet.Finally,the state change of the auxiliary contact is used to determine the time point of just opening (just closing) and the time of opening and closing,and the measurement results are within the allowable error range.

Discussion on Inductance Measurement of DC Contactor Coil for New Energy Electric Vehicle at Power Failure Moment

HUANG Fang, ZHANG Lixi, ZHANG Yan

2022, 0(10):  78-80.  doi:10.16628/j.cnki.2095-8188.2022.10.013

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Aiming at the inductance measurement of DC contactor coil for new energy vehicles at the moment of power failure,a high sampling frequency recorder (or oscilloscope) is proposed to measure the maximum inductance of DC contactor coil at the moment of power failure by recording the current waveform of instantaneous coil disconnection.The recorder is used to measure the micro drop time of the contactor current,so as to calculate the inductance of the contactor coil at the moment of power failure,which can provide the key data for the power distribution unit (PDU) of new energy electric vehicles and ensure the design safety of the control system.

Power Theft Detection Method Based on Generative Adversarial Networks

ZHU Yueyao, WEI Xingqi, ZHANG Chenyu

2022, 0(10):  81-86.  doi:10.16628/j.cnki.2095-8188.2022.10.014

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To address the imbalance problem of power theft data in the context of the smart grid,a method of power theft detection based on generative adversarial networks (GAN) is proposed.The generator is responsible for generating false samples to deceive the discriminator,and the discriminator is responsible for distinguishing the real samples from the generated samples.The generation ability of the generator and the discrimination ability of the discriminator can be imporved through the adversarial training of the two,thus the accuracy and anti-interference ability of power theft detection can be improved.The accuracy and superiority of the proposed algorithm are validated by the example results.