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11th International Conference on Electrical Machines and systems, ICEMS 2008

作者： Yi, Lei Zhengming, Zhao Jing, Xue State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing 100084 China

ISBN: (纸本)9787506292214

Three-phase induction motors as well as power converters are intrinsically efficient machines and devices. However, due to the common misapplication of them with loads like pumps and fans, these electric machine systems are considered a great potential of energy conservation in industries. As to assessing methods of energy conservation, neither the study of induction machine efficiency nor the analysis of pumps and fans performance is new. However, the systematic and qualitative analysis and assessment of the energy efficiency of induction machines, loads and control devices acting as a whole system are still complicated yet indispensable for electric machine system energy conservation program in China. In this paper, a systematic and qualitative assessment method for energy application efficiency of electric machine system is raised. Based on this method, an assessing computer program is designed to provide referencing information for making investment decisions regarding energy efficiency measures at manufacturing plants. An expert system is also designed to choose equipments that match each other.

关键词： Investments

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Application of fuzzy-rough set theory and improved SMO algorithm in aircraft engine vibration fault diagnosis

Application of fuzzy-rough set theory and improved SMO algor...

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2012 3rd Annual IEEE Prognostics and system Health Management Conference, PHM-2012

作者： Xu, Hongzhi Jiang, Dongxiang Liang, Lei State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Thermal Engineering Tsinghua University Beijing 100084 China

Aircraft engine is an important component of the airplane, which lifespan and reliability have directly influence to flight safety. Vibration analysis is an effective fault diagnosis method for airplane's mechanical construction fault. Several typical vibration faults have drawn from the vibration analysis on the basis of fault mechanism in aircraft engine, and the standard vibration fault-symptom (Fuzzy Membership) relationship table have constructed based on Fuzzy Mathematic theory in this paper. Sample data are simulated on the basis of this table. Sequential Minimal Optimization (SMO) is a fast algorithm for training Support Vector Machines (SVM). The simulated result showed a great improvement on computation efficiency by selecting double threshold parameter for SMO algorithm than single threshold. In order to examine the algorithm's effect applying in the aircraft engine fault diagnosis, Radial Basis Function (RBF) Neural Network, C4.5 Decision Tree, SVM (chunking), Platt's SMO and Improved SMO algorithm are applied to the training data and test data. It is shown that the Improved SMO algorithm displayed superior comprehensive performance. Finally, the vibration fault feature is reduced based on Fuzzy-Rough Sets theory. The research shows that the Improved SMO algorithm is quicker than other algorithm in aircraft engine fault diagnosis with the reduced feature attributes, and its accuracy is high. © 2012 IEEE.

关键词： Support vector machines

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Series-connected HV-IGBTs using active voltage control with status feedback circuit

Series-connected HV-IGBTs using active voltage control with ...

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作者： Ji, Shiqi Lu, Ting Zhao, Zhengming Yu, Hualong Yuan, Liqiang State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing100084 China

ISBN: (纸本)9781479956982

The transient voltage unbalance is the major problem that limits the application of series-connected IGBTs in high voltage and high power converters. The asynchronous gate delay which causes that series-connected IGBTs do not turn-on and turn-off at the same time results in the most serious unbalanced voltage sharing. The active voltage control technique is proposed in this paper to solve the asynchronous gate delay problem. By sampling the feedback signal caused by unbalanced voltage, the microcontroller generates a time delay for gate driver to compensate the asynchronous gate delay. The most vital part of active voltage control is the status feedback circuit which is also given in detail in this paper. The function of the status feedback circuit and the effect of active voltage control are verified in a two series-connected HV-IGBTs platform in rated operation (5kV bus voltage and 600A load current). © 2014 IEEE.

关键词： Insulated gate bipolar transistors (IGBT)

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Misalignment fault detection in dual-rotor system based on time frequency techniques

Misalignment fault detection in dual-rotor system based on t...

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Society for Machinery Failure Prevention Technology Annual Conference 2017: 50 Years of Failure Prevention Technology Innovation, MFPT 2017

作者： Wang, Nan-Fei Jiang, Dong-Xiang Han, Te State Key Laboratory of Control Simulation of Power System and Generation Equipment Department of Thermal Engineering Tsinghua University Beijing100084 China

In order to improve the energy efficiency and compact structure, the dual-rotor structure including lowpressure rotor and high-pressure rotor has been widely used in aero-engine. Misalignment is one of the most common faults in dual-rotor system, which will causes malfunctions. It is a significant task for rotor dynamics personnel to monitor and defect faults in dual-rotor system. In the paper, the dual-rotor vibration signals are applied to solve the fault identification problem by utilizing time frequency techniques. Numerical simulations are carried out through finite element analysis of dual-rotor system with misalignment fault. Two signal processing tools namely Short Time Fourier Transform (STFT) and Continuous Wavelet Transform are used to detect the misalignment fault and compared to evaluate their diagnosis performance. The effect of addition of Signal to Noise (SNR) on three frequency techniques is presented. Experiments are carried out to obtain the vibration data of dual-rotor test rig and the results from the work show that the technique can be used for the monitoring of misalignment, which will have applications in the condition monitoring and maintenance of various types of rotating machinery.

关键词： Condition monitoring

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Inspection Text Classification of power equipment Based on TextCNN 16th

Inspection Text Classification of Power Equipment Based on T...

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16th Annual Conference of China Electrotechnical Society, ACCES 2021

作者： Chen, Jianning Zhou, Yuanxiang Ge, Jiamin State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing100084 China

ISBN: (纸本)9789811918698

A large number of text and reports about the power equipment are generated in power system, which consist of implicit information of operation condition and insulation status. With the development of convolutional neural network (CNN), the inspection text can be analyzed intelligently to improve the reliability of power system. In order to extract valuable information from inspection text for state evaluation of power equipment in local area, an information extraction model for inspection text based on TextCNN is proposed, improved and verified. First, the feature embedding of inspection text were performed by Word2Vec method. Secondly, the corpus were augmented with back translation method. Then, the TextCNN was adopted to classify the risk level of the power equipment or area involved in the inspection text. Finally, the classification results from the model were evaluated by classification accuracy, F1 score, confusion matrix and compared with the model based on BiLSTM and RCNN. The results demonstrated that the performance of TextCNN was the best among the three models on augmented dataset by back translation method with ACC and F1 scores of 0.9087 and 0.9099, respectively, which is the most suitable model among these three for recognition and classification of inspection text of power equipment. © 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

关键词： Inspection

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Research focuses and advance technologies of smart grid in recent years

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Chinese Science Bulletin 2012年第22期57卷 2879-2886页

作者： MEI ShengWei CHEN LaiJun State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Department of'Electrical EngineeringTsinghuaUniversityBeijing 100084China

The smart grid is attracting more and more attention in electrical engineering for its promising ***,huge challenges also exist in the implementations of the smart grid,such as high penetration of renewable energy resources,low carbon electricity and cyber-physical security,*** this paper,the latest progress of some research focuses and advance technologies in the development of smart grid is reviewed.

关键词：电网智能技术网络物理安全可再生能源电气工程渗透力

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PEEC method for modeling current distribution in grounding plane

PEEC method for modeling current distribution in grounding p...

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ICEMS 2005: 8th International Conference on Electrical Machines nd systems

作者： Hau, Beibei Sun, Xudong Jiang, Jianguo State Key Laboratory of Control and Simulation of Power System and Generation Equipment Dept. of Electrical Engineering Tsinghua University Beijing 100084 China

ISBN: (纸本)7506274078

In view of the impossibility of current measurement in actual grounding plane in power electronic equipment, an equivalent circuit model is set up in this paper using the partial element equivalent circuit (PEEC) method to simulate and calculate current distribution in grounding plane. The inductance parameters calculated are fairly coincident with experiment results, and some conclusions of current distribution are summarized. It is shown that the equivalent circuit model using PEEC method presented in this paper is a feasible and promising way to model and calculate current distribution in grounding plane.

关键词： Electric load distribution

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Life prediction and reliability analysis of motorbearing based on vibration signal 7

Life prediction and reliability analysis of motorbearing bas...

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7th International Conference on Reliability of Electrical Products and Electrical Contacts, ICREPEC 2019

作者： Xu, Helin Cheng, Lin Wan, Yuxiang Qi, Ning State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing100084 China

ISBN: (纸本)9789881532343

As an important power equipment in the power system, the electrialc motor is an important part of the transformation of electric energy and mechanical energy. Reasonable prediction of the reliability level of the running motor, timely and effectively avoid the operational risks, can effectively ensure the safety and stable operation of the power system. This paper starts with the motor vibration signal and establishes the remaining life prediction based on SVM(Support Vector Machine). Firstly, the vibration signal is denoised by wavelet transform, and the characteristic parameters such as mean square value is extracted after signal data reconstruction. Further, combined with the characteristic value, the working state is divided, and the support vector machine regression prediction model is used to obtain the remaining life of the bearing. In the case study part, data denoising and feature extraction are performed on the bearing vibration data measured by the PRONOSTIA test bench. The trend of the selected characteristic values is used for evaluating the motor operating state. The characteristic value, running state of the equipment, and remaining life which are extracted from the training set data are input to the SVM, and then the SVM is used to predict the remaining life for the test set. Finally, failure rate of the equipment can be derived. © 2019 by International Academic Publishers Ltd.

关键词： Reliability analysis

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Experimental study on grounding mode of secondary cable shielding layer of uhv converter station 11

Experimental study on grounding mode of secondary cable shie...

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11th Asia-Pacific International Conference on Lightning, APL 2019

作者： Zhang, Zhaohua Shi, Weidong Kang, Peng Zhang, Bo Liu, Zhuoran Shi, Lei China Electric Power Research Institute Beijing China State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Yinchuan China

ISBN: (纸本)9781728116952

Because of a lightning strike, short circuit fault, and switch operation, grounding grid will be impacted by high-frequency current, which makes the grounding grid appear uneven distribution of transient grounding potential, this kind of transient grounding potential rise will be coupled to the core wire through the outer surface of the cable and will invade the secondary system, which may have an impact on the normal operation of the secondary equipment and Endanger the safe and stable operation of substation or converter station. In addition, with the digitalization, electronization, and localization of the secondary equipment in the UHV converter station, a large number of precision secondary equipment used for protection, control and communication is placed in the high-voltage switching field of the converter station, which greatly increases the probability of interference with the secondary system of the UHV converter station. It is well known that using shielded cables and choosing correct grounding mode of the shielding layer is an important measure to improve the electromagnetic compatibility of converter stations. In this paper, based on a test method to research transient grounding potential rise in converter station, the transient overvoltage of multi-segment secondary cables and their shielding layer with different grounding modes are measured in the field of an AC filter in a UHV converter station. The test results show that the grounding of the shielding layer between the first and the last sections is the key to suppress transient overvoltage for the multi-segment control cable. The best grounding method is to increase the shielding layer and armor layer of the control cable between the on-site control cabinet to be grounded at the single end of the B-phase on-site control cabinet based on the cable grounding mode. That is to say, the cable of the shielding layer and the armor layer between the on-site control cabinet should consider the grounding at

关键词： Electric grounding

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A Fuzzy Hierarchical Strategy for Improving Frequency Regulation of Battery Energy Storage system

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Journal of Modern power systems and Clean Energy 2021年第4期9卷 689-698页

作者： Kaifeng Wang Ying Qiao Lirong Xie Jiaming Li Zongxiang Lu Huan Yang School of Electrical Engineering Xinjiang UniversityUrumqiChina State Key Laboratory of Control and Simulation of Power Systems Generation Equipments of Electrical Engineering Tsinghua UniversityBeijingChina

Battery energy storage systems(BESSs)can provide instantaneous support for frequency regulation(FR)because of their fast response ***,purely pursuing a better FR effect calls for continually rapid cycles of BESSs,which shortens their lifetime and deteriorates the operational *** coordinate the lifespan savings and the FR effect,this paper presents a control strategy for the FR of BESSs based on fuzzy logic and hierarchical *** fuzzy logic controller improves the effect of FR by adjusting the charging/discharging power of the BESS with a higher response speed and precision based on the area control error(ACE)signal and the change rate of ACE in a non-linear *** controllers effectively reduce the life loss by optimizing the depth of discharge,which ensures that the state of charge(SOC)of BESS is always in the optimal operating range,and the total FR cost is the lowest at this *** proposed method can achieve the optimal balance between ACE reduction and operational economy of *** effectiveness of the proposed strategy is verified in a two-area power system.

关键词： Battery energy storage system(BESS) frequency regulation(FR) coordinated control strategy optimal depth of discharge charging/discharging threshold

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