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Joint Conference on Society for Machinery Failure Prevention Technology Conference, MFPT 2015 and ISA's 61st International Instrumentation Symposium, IIS 2015 - Technology Evolution: Sensors to systems for Failure Prevention

作者： Liu, Chao Jiang, Dongxiang Yang, Wenguang State Key Laboratory of Control and Simulation of Power System and Generation Equipments Department of Thermal Engineering Tsinghua University Beijing100084 China

The measured parameters change with the machine degradation, where the trends of the parameters can be applied in condition prediction. The deterioration of the parameters usually present characteristics in a monotonic or low-frequency way. As the measure signal are merged with instant signals, noise and measurement error in different frequency bands, model decomposition approaches are widely applied to separate the different bands for feature extraction. Among the model decomposition methods, Variational model decomposition is recently proposed by K. Dragomiretskiy and D. Zosso as a non-recursive model which can extract modes concurrently. This work will analyze its effectiveness in degradation feature extraction and application in condition prediction in prognosis. Firstly, variational model decomposition is analyzed, where the characteristics of variational model decomposition are compared with another mode decomposition method ensemble empirical mode decomposition. simulation data is applied to test the effectiveness of the mode decomposition methods. Secondly, field data with component degradation is collected, and the degradation feature extraction is applied with the three methods mentioned above.

关键词： Empirical mode decomposition

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Dimensionality reduction analysis in condition classification of prognostics

Dimensionality reduction analysis in condition classificatio...

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Applied systems Health Management Conference 2011: Enabling Sustainable systems, MFPT 2011

作者： Liu, Chao Jiang, Dongxiang State Key Laboratory of Control and Simulation of Power System and Generation Equipments Department of Thermal Engineering Tsinghua University Beijing 100084 China

In order to maintain the separability of different fault onsets, more characteristic parameters need to be used to establish the feature space with multiple possible faults. Usually, the dimensions of feature space have a positive correlation with the number of faults. Describing multiple faults in visualization is more difficult and the classification bounds with hyperplanes are less convenient to realize. Therefore implementing dimensionality reduction approaches in original feature space is beneficial for fault diagnosis and prognostics. Multidimensional Scaling (MDS) has been widely studied and used for dimensionality reduction as well as Principal Component Analysis (PCA). When these methods are applied in the prognostics process, the effectiveness needs validation with the reason that the deterioration features in degradations are different from the faults onsets that in diagnostics. The paper analyzes the nonlinear dimensionality reduction methods including Self-Organizing Map (SOM) and Isometric feature mapping (Isomap). Based on the deterioration data in an engine, the effects of these methods are analyzed.

关键词： Self organizing maps

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Comprehensive power-supply planning for active distribution system considering cooling,heating and power load balance

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Journal of Modern power systems and Clean Energy 2015年第4期3卷 485-493页

作者： Xinwei SHEN Yingduo HAN Shouzhen ZHU Jinghong ZHENG Qingsheng LI Jing NONG State Key Lab of Control and Simulation of Power Systems and Generation Equipments Department of Electrical EngineeringTsinghua UniversityBeijing 100084China Grid Planning&Research Center Guizhou Power Grid CooporationCSGGuiyang 550002China

An active distribution system power-supply planning model considering cooling,heating and power load balance is proposed in this paper.A regional energy service company is assumed to be in charge of the investment and operation for the system in the *** expansion of substations,building up distributed combined cooling,heating and power(CCHP),gas heating boiler(GHB)and air conditioner(AC)are included as investment planning *** terms of operation,the load scenarios are divided into heating,cooling and transition ***,the extreme load scene is included to assure the power supply reliability of the *** results demonstrate the effectiveness of the proposed model and illustrate the economic benefits of applying distributed CCHP in regional power supply on investment and operation.

关键词： Active distribution system Combined cooling heating and power(CCHP) power-supply planning Load balance

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Protection of microgrid

Protection of microgrid

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10th IET International Conference on Developments in power system Protection, DPSP 2010

作者： Shi, Shenxing Jiang, Bo Dong, Xinzhou Bo, Zhiqian State Key Lab. of Control and Simulation of Power Syst. and Generation Equipments Tsinghua University Beijing China Areva TandD Stafford United Kingdom

ISBN: (纸本)9781849192125

The paper analyses the existed protection of microgrid. And in order to meet the requirements of microgrid protection, a novel protection is presented in this paper. The protection based on local information without the need of communication, uses current traveling waves to identify faulted feeder, and the bus bar voltages to determine a event caused by fault or switch operation. In the protection scheme, current traveling waves are measured by current transducers in N line and phase lines, and wavelet multi-resolution analysis is used to decompose traveling wave signals. The initial traveling waves are compared in magnitude and polarity with each other to determine the faulted feeder. The protection is independent of microgrid operation connected with the main power grid or in island.

关键词： Electric power system protection

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Research on platform for advanced contorl of energy storage system

Research on platform for advanced contorl of energy storage ...

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2nd IET Renewable power generation Conference, RPG 2013

作者： Xu, Hanchen Yuan, Zhichang Lu, Chao Wang, Can Guo, Haifeng Li, Yongxing State Key Laboratory of Control and Simulation of Power System and Generation Equipments Tsinghua University Beijing 100084 China China Southern Power Grid Power Generation Company Guangzhou 510630 China

ISBN: (纸本)9781849197588

Advanced applications of energy storage system comprise load shifting, isolated island operation, frequency regulation and reactive support, etc. There are already algorithms and control strategies for advanced applications, but still lack an independent supporting software platform. This paper concentrates on the structure and realization of software platform for advanced application of large-scale energy storage system, including demand analysis, software architecture and module design, user interface and functionality development. An easy to operate and expand software platform, with a beautiful graphical user interface and support for visualization of data, was designed and implemented.

关键词： Energy storage

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Switching Current Imbalance Mitigation for Paralleled SiC MOSFETs Using Common-mode Choke in Gate Loop 12

Switching Current Imbalance Mitigation for Paralleled SiC MO...

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12th Annual IEEE Energy Conversion Congress and Exposition, ECCE 2020

作者： Liu, Jiye Zheng, Zedong Tsinghua University State Key Lab of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Beijing China

ISBN: (纸本)9781728158266

Paralleling SiC MOSFETs is a popular way to increase the current capacity. However, due to asymmetric layout, device parameter mismatch and other factors, imbalanced switching or dynamic current is observed among the paralleled switches in multi-device paralleling application which results in unequal switching loss, challenging the security and reliability of the system. In this paper, a common-mode choke in the gate loop is proposed and analyzed to suppress the imbalanced switching current induced by asymmetric layout in a half-bridge configuration with a Kelvin-source connection. The mechanism of the proposed method is comprehensively investigated to show that though the common-mode choke is placed in the gate loop, it can also mitigate the imbalanced current caused by asymmetric power loop. And it also shows that only the leakage inductance of the choke is seen in the gate loop and thus the switching speed is not expected to be influenced. The proposed method can be easily extended to multi-device paralleling application and the switching transients is hardly influenced by the common-mode choke. simulation and experimental results are presented to verify the proposed method. © 2020 IEEE.

关键词： Silicon

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Study on the Prediction Methods of Aero Engine Fault Parameters

Study on the Prediction Methods of Aero Engine Fault Paramet...

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2015 International power,Electronics and Materials Engineering Conference(IPEMEC 2015)

作者： Li Dewang Jiang Dongxiang State Key Laboratory of Control and Simulation of Power System and Generation Equipments De partment of Thermal EngineeringTsinghua University

ISBN: (纸本)9781510806474

This paper uses the least squares method,BP neural network and gray GM(1,1) model for trend forecasts and predicting the remaining life of the aero-engine fault *** comparing the results of the three methods,the least squares method and BP neural network method predicting results are more exact than the gray GM(1,1) *** three methods are also used for predicting the actual data,and the result is close to the real.

关键词： aero-engine characteristic parameters prediction methods

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Application of back propagation neural network to fault diagnosis of direct-drive wind turbine

Application of back propagation neural network to fault diag...

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2010 2nd World Non-Grid-Connected Wind power and Energy Conference, WNWEC 2010

作者： An, Xueli Jiang, Dongxiang Li, Shaohua State Key Laboratory of Control and Simulation of Power System and Generation Equipments Dept. of Thermal Engineering Tsinghua University Beijing 100084 China

ISBN: (纸本)9781424489213

The vibration signals of wind turbines are highly nonlinear and non-stationary due to wind turbine operation conditions that are very complicated. The signals will be more complex when a fault occurs. Aiming at these problems, a fault diagnosis method for direct-drive wind turbine is presented based on back propagation neural network (BPNN). The time-domain feature parameters of vibration signals in the horizontal and vertical direction are considered in the method. Five experiments of direct-drive wind turbine with normal, wind wheel mass imbalance, wind wheel aerodynamic imbalance, yaw and blade break are carried out in lab.ratory scale. Through analyzing the features of five conditions, the time-domain feature parameters in horizontal and vertical direction of the vibration signal are selected as the input samples of BPNN. By training, the BPNN model can be constructed between feature parameters and fault types. The validity of the BPNN model is verified using test samples. The results indicate that the proposed method has higher diagnostic accuracy. It can used in on-line fault diagnosis of direct-drive wind turbines. © 2010 IEEE.

关键词： Failure analysis

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Analyses on frequency transmission characteristic of traveling wave in distribution power system

Analyses on frequency transmission characteristic of traveli...

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2011 International Conference on Advanced power system Automation and Protection, APAP 2011

作者： Wang, Jun Shi, Shenxing Dong, Xinzhou Wang, Bin State Key Lab. of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China

ISBN: (纸本)9781424496198

Under the skin effect caused by the alternating electromagnetic field, the transmission line parameters changes with frequency, and different line resistivity, surge impedance, wave speed are presented in one line under the different frequency bands of signal. This phenomenon is usually called Frequency transmission characteristic, which is mainly discussed in this paper. This paper first studied the line resistivity, wave speed and surge impedance of zero-mode component and line-mode component in different frequency bands. Then, the line structure and its effection on Frequency transmission characteristic are presented. Last, the frequency transmission characteristic on a certain line fault is discussed based on a typical distribution system model. The research in this paper is meaningful for future study on the fault feeder selection and fault location technology based on traveling wave in the distribution system. © 2011 IEEE.

关键词： Wavelet transforms

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Research on the process of power flow transferring and its identification method

Research on the process of power flow transferring and its i...

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2011 International Conference on Advanced power system Automation and Protection, APAP 2011

作者： Liu, Kun Dong, Xinzhou Wang, Bin Shi, Shenxing State Key Lab. of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China

ISBN: (纸本)9781424496198

This paper analyzes the general process of power flow transferring and divides it into four parts: 1) the process of first phase selection after fault occurs;2) the process of selective action at the first time;3) the process of second phase selection and status confirmation;4) the process after status confirmation. It points out that the issue of asymmetrical flow transferring is a critical process which must be put emphasis on. Then it proposes a method to identify this process, and discuss different solution methods. © 2011 IEEE.

关键词： Electric load flow

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