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Analysis on the fault characteristics of three-phase short-circuit for half-wavelength AC transmission lines

Global Energy Interconnection 2018年第2期1卷 115-121页

作者： Xuankun Song Teng Feng Liu Han Travis MSmith Xinzhou Dong Wenxuan Liu Rui Zhang State Grid Economic and Technological Research Institute CO. LTD. Oak Ridge National Laboratory Tsinghua University

Half-wavelength AC transmission(HWACT) is an ultra-long distance AC transmission technology, whose electrical distance is close to half-wavelength at the system power frequency. It is very important for the construction and operation of HWACT to analyze its fault features and corresponding protection technology. In this paper, the steady-state voltage and current characteristics of the bus bar and fault point and the steady-state overvoltage distribution along the line will be analyzed when a three-phase symmetrical short-circuit fault occurs on an HWACT line. On this basis, the threephase fault characteristics for longer transmission lines are also studied.

关键词： Half-wavelength AC transmission fault characteristics Three-phase short-circuit fault distance Overvoltage

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fault characteristics Analysis for Rotor Systems with Misalignment Based on Wavelet Packet Decomposition and Frequency-band Energy Ratio Analysis

Fault Characteristics Analysis for Rotor Systems with Misali...

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第三十届中国控制会议

作者： ZHANG Shuai~1,QU Yanhuai~1,HAN Qingkai~2 1.School of Information and Electronic Engineering,Shandong Institute of Business and Technology,Yantai 264005,P.R.China 2.School of Mechanical Engineering and Automation,Northeastern University,Shenyang 110819,P.R.China

＜正＞In this paper,combining with model experiment,fault characteristics of single-span and dual-disc rotor system with bearing misalignment are investigated by the combination of Wavelet Packet Decomposition（WDP） and frequency -band energy ratio analysis ***,resampling is applied to ensure the accurate and efficient decomposition of signal *** then with the mother wavelet function ’db44’,the displacement signals were decomposed into 4 ***,through a comparison with the time-domain waveforms and amplitude spectrums of decomposed signals in different decomposing levels,the effects of different misalignments to system vibration are *** corresponding frequency-band energy ratio values can have an excellent corresponding relationship with the misalignment degree and actual speed which can be applied to fault feature extraction to implement effective diagnosis of misalignment fault.

关键词： Model Experiment Bearing Misalignment fault characteristics Single-span and Dual-disc Rotor System Wavelet Packet Decomposition Frequency-band Energy Ratio Analysis

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Research on The fault characteristics and fault Diagnosis Methods of Three-level High-power Inverter

Research on The Fault Characteristics and Fault Diagnosis Me...

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2009 IEEE 6th International Power Electronics and Motion Control Conference-ECCE Asia

作者： Zhou Jinghua Liu Huichen Chen Yaai Li Zhengxi Power Electronics and Motor Driver Engineering Center North China University of Technology Beijing 100144 China

As one kind of multilevel inverters, three-level inverter is widely used in the high-power and high-voltage applications. However, the increasing of the power devices improves the system’s fault rate. How to ensure stable operation of the system has become an important research question. Through theoretical analysis and simulation on three-level high-power inverter, the paper analyses the working situation of the power devices of main circuit under the open-circuit fault, the specific fault characteristics and the typical waveform in detail, and sums up the rules of fault diagnosis. Finally, based on the three-level high-power inverter, the open-circuit fault experiment of power devices is carried out .The experimental results further validate the fault analysis and simulation results of the power devices.

关键词： three-level inverter power devices fault characteristics fault diagnosis

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A fault Risk Warning Method of Integrated Energy Systems Based on RelieF-Softmax Algorithm

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Computer Modeling in Engineering & Sciences 2022年第9期132卷 929-944页

作者： Qidai Lin Ying Gong Yizhi Shi Changsen Feng Youbing Zhang Pingyang County Changtai Power Industry Co. Ltd.Wenzhou325400China College of Information Engineering Zhejiang University of TechnologyHangzhou310023China

The integrated energy systems,usually including electric energy,natural gas and thermal energy,play a pivotal role in the energy Internet project,which could improve the accommodation of renewable energy through multienergy complementary *** on the regional integrated energy system composed of electrical microgrid and natural gas network,a fault risk warning method based on the improved RelieF-softmax method is proposed in this *** raw data-set was first clustered by the K-maxmin method to improve the preference of the random sampling process in the RelieF algorithm,and thereby achieved a hierarchical and non-repeated ***,the improved RelieF algorithm is used to identify the feature vectors,calculate the feature weights,and select the preferred feature subset according to the initially set *** addition,a correlation coefficient method is applied to reduce the feature subset,and further eliminate the redundant feature vectors to obtain the optimal feature ***,the softmax classifier is used to obtain the early warnings of the integrated energy *** studies are conducted on an integrated energy system in the south of China to demonstrate the accuracy of fault risk warning method proposed in this paper.

关键词： Integrated energy system RelieF-softmax method fault characteristics fault risk level prediction

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Research on fault mode and diagnosis of methane sensor

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Journal of China University of Mining and Technology 2008年第3期18卷 386-388页

作者： WANG Qi-jun CHENG Jiu-long Huainan Vocational ＆ Technical College Huainan Anhui 232001 China Shandong University of Science and Technology Qingdao Shandong 266510 China

To improve the reliability of coal mine safety monitoring systems we have analyzed the characteristics of a methane sensor, an important component of the monitoring system of production safety in a coal mine and studied the main type and mode of faults when the sensor was used on-line. We introduced a new method based on artificial neural network to detect faults of methane sensors. In addition, using the output information of a single methane sensor, we established a sensor output model of a dynamic non-linear neural network for on-line fault detection. Finally, the fault of the heating wire of the sensor was simulated, indicating that, when the methane sensor had a fault, the predicted output of the neural network clearly deviated from the actual output, exceeding the pre-set threshold and showing that a fault had occurred in the methane sensor. The result shows that the model has good convergence and stability, and is quite capable of meeting the requirements for on-line fault detection of methane sensors.

关键词： methane sensor fault characteristics fault diagnosis neural network

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fault isolation of air handling unit based on neural network

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Journal of Southeast University(English Edition) 2010年第2期26卷 355-358页

作者：杜志敏晋欣桥杨学宾范波上海交通大学制冷与低温工程研究所上海200240

Aiming at various faults in an air conditioning system,the fault characteristics are *** influence of the faults on the energy consumption and thermal comfort of the system are also *** simulation results show that the measurement faults of the supply air temperature can lead to the increase in energy *** to the fault characteristics,a data-driven method based on a neural network is presented to detect and diagnose the faults of air handling ***,the historical data are selected to train the neural network so that it can recognize and predict the operation of the ***,the faults can be diagnosed by calculating the relative errors denoting the difference between the measuring values and the prediction ***,the fault diagnosis strategy using the neural network is validated by using a simulator based on the TRNSYS *** results show that the neural network can diagnose different faults of the temperature,the flow rate and the pressure sensors in the air conditioning system.

关键词： air handling unit fault characteristics fault isolation neural network

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The application of evidence theory based on DWT in bearing fault diagnosis of large equipment

The application of evidence theory based on DWT in bearing f...

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第32届中国控制与决策会议

作者： Liancheng MA Yong ZHANG Xingyu DONG Fang CAO Yuhang LIU Anshan iron and steel group mining co.LTD Qi Dashan Branch College of electronic information and engineering Liaoning University of science and technology Northeast University Science and technology group Liaoning University of Engineering and Technology

In view of the problems of bearing failure in industrial production, such as high incidence, great harm and hard to detect, this paper proposed a relatively mature evidence theory and an improved method, which has been well applied in engineering practice. Wavelet analysis is still in the development stage in China, but its value can not be ignored because of its own time-frequency characteristics. In this paper, the bearing vibration signals of equipment and motor are firstly decomposed into several easily distinguishable sub signals by wavelet decomposition, and then the redundant features are reduced by rough set and the central calculation method in evidence theory is used for fusion. Finally the fault types are identified accurately and the numerical simulation experiment of bearing fault classification is executed. The experimental results showed that the wavelet decomposition can extract the features of bearing fault information, which indicates that the fault diagnosis model in this paper can achieve high-precision bearing fault diagnosis and classification.

关键词： fault diagnosis evidence theory wavelet analysis rough set fault characteristics

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