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2008 IEEE Vehicle power and Propulsion Conference, VPPC 2008

作者： Ting, Lu Zhengming, Zhao Liqiang, Yuan Shuping, Wang State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China

ISBN: (纸本)9781424418497

Instantaneous energy balancing plays an important role in power electronics conversion. The unbalance of electromagnetic energy not only debases the system performance but also decreases the reliability and efficiency of the conversion. In this paper, instantaneous energy balancing problems in three-level neutral point clamped (NPC) converters are classified and discussed. Typical examples and their usual solutions of each kind of problems are expounded and compared. In the end of this paper, limitations and disadvantages of traditional methods are analyzed, and electromagnetic field method is summarized as the new trend to analyze electromagnetic energy transmission and exchange. The method using electromagnetic field theory is emphasized to be the better approach to solve the aforementioned energy balancing problems. © 2008 IEEE.

关键词： Electromagnetic waves

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Traveling waves based fault line selection using sparse representation 8

Traveling waves based fault line selection using sparse repr...

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8th IEEE International Conference on Advanced power System Automation and Protection, APAP 2019

作者： Xu, Wen Shi, Shenxing Dong, Xinzhou Zhang, Guangmei Tsinghua University State Key Laboratory of Control and Simulation of Power System and Generation Equipment Beijing China

ISBN: (纸本)9781728117225

Traveling wave method has been proved to be effective in fault line selection of power distribution system with the neutral non-effectively grounded. However, it can be easily disturbed by non-faulty traveling wave when selecting the line. For this reason, this paper proposes a new traveling wave line selection method based on sparse representation, in which current traveling wave signals are measured for the selection task. The algorithm of selection is based on the idea that all non-zero terms in the sparse coefficients of the measured signal are found to be associated with training samples from a single class, and the test samples can be easily assigned to the class. This makes it possible to distinguish between the non-faulty traveling wave and the real fault traveling wave. © 2019 IEEE.

关键词： compressed sensing distribution system line selection sparse representation traveling wave

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An Adaptive Restart Method for DC Transmission Line in LCC-HVDC System 8

An Adaptive Restart Method for DC Transmission Line in LCC-H...

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8th IEEE International Conference on Advanced power System Automation and Protection, APAP 2019

作者： Cai, Jing Dong, Xinzhou Tsinghua University State Key Laboratory of Control and Simulation of Power System and Generation Equipment Beijing China

ISBN: (纸本)9781728117225

DC-line fault recovery sequence (DFRS) is widely implemented in LCC-HVDC system to realize fast recovery in case of temporary fault. When permanent fault occurs, restart still happens several times as preset, resulting in repeated impacts and reducing the stability and reliability of the system. An adaptive restart for DC line fault is studied in this paper to deal with this problem. Firstly, the converter valves states and DC voltage characteristics under temporary fault and permanent fault are analyzed respectively. Then, a method based on DC voltage control is proposed to distinguish different fault states. Current DFRS strategy is improved by adding this process, through which the fault pole will only restart after the temporary fault disappearing, while directly blocked when a permanent fault is recognized. Fault handling time can be shortened and negative effects of DC line fault are minimized. The simulation results verify feasibility and effectiveness of proposed method. © 2019 IEEE.

关键词： HVDC power transmission

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A novel modbus RTU-based communication system for adjustable speed drives

A novel modbus RTU-based communication system for adjustable...

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2008 IEEE Vehicle power and Propulsion Conference, VPPC 2008

作者： Sideng, Hu Zhengming, Zhao Yingchao, Zhang Shuping, Wang State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University Beijing China

ISBN: (纸本)9781424418497

The communication protocol is important for applying adjustable speed drive (ASD) systems to an industry network. This paper proposes a novel scheme of communication system for the ASD system based on Modbus protocol. The most remarkable advantage of the approach lies in the tradeoff between performance and economic cost for a power converter system. The overall system is built on master-slave structure and easy for interacting with other networks. An additional study on the cyclic redundancy check (CRC) in Modbus RTU is introduced to obtain the optimization design in the actual application and the optimization method in software design is also presented. The performance of the communication system obtained from experiment conducted on the 15kW ASD system validates the effectiveness of the proposed design method. © 2008 IEEE.

关键词： Software design

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generation of Atmospheric Pressure Plasma by Repetitive Nanosecond Pulses in Air Using Water Electrodes

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Plasma Science and Technology 2011年第6期13卷 735-739页

作者：邵涛于洋章程姜慧严萍周远翔 Institute of Electrical Engineering Chinese Academy of Sciences Key Laboratory of Power Electronics and Electric Drive Chinese Academy of Sciences State Key Laboratory of Control and Simulation of Power Systems and Generating Equipment Electrical Engineering DepartmentTsinghua University

Dielectric barrier discharge （DBD） excitated by pulsed power is a promising method for producing nonthermal plasma at atmospheric pressure. Discharge characteristic in a DBD with salt water as electrodes by a home-made unipolar nanosecond-pulse power source is presented in this paper. The generator is capable of providing repetitive pulses with the voltage up to 30 kV and duration of 70 ns at a 300 Ω resistive load. Applied voltage and discharge current are measured under various experimental conditions. The DBD created between two liquid electrodes shows that the discharge is homogeneous and diffuse in the whole discharge regime, Spectra diagnosis is conducted by an optical emission spectroscopy. The air plasma has strong emission from nitrogen species below 400 nm, notably the nitrogen second positive system.

关键词： non-thermal plasma dielectric barrier discharge pulsed power nanosecondpulse pulse repetition frequency atmospheric pressure air emission spectra.

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Expectative Modeling of Wide-area Damping Networked control systems with Long Stochastic Time Delay

Expectative Modeling of Wide-area Damping Networked Control ...

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第25届中国控制与决策会议

作者： Zhang Xinran Lu Chao Han Yingduo State Key Laboratory of Control and Simulation of Power System and Generation Equipments Tsinghua University

ISBN: (纸本)9781467355339

In this paper, the impact of stochastic time delay on wide-area damping networked control systems is analyzed. A disintegrate method of time-delay upon sampling period is approved. Furthermore, the expectative model of networked control systems with long and stochastic time delay, whose variance extent is larger than one sampling period, is theoretically proved and calculated. Finally, the effectiveness of this expectative model is confirmed on the simulation of a power system with 8 generators and 36 nodes.

关键词： Networked control System, Wide Area Damping control, Long Stochastic Time Delay, Expectative Model.

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Calculation on the thermal field of the water cooling stator of three-gorge hydro-generator

Calculation on the thermal field of the water cooling stator...

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

作者： Wang, H.Y. Su, P.S. Wang, X.H. Department of Electrical Engineering State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing 10084 China

ISBN: (纸本)7506274078

To simplify the calculation of winding bar temperature for the condition monitoring of the water cooling stator of Three-Gorge Hydro-Generator, this paper calculates three of two-dimension thermal fields. Using the three fields simulates the different section along the axial direction of the generator. The total amount of heat taken away by water can be calculated by weighting the result of three fields on the total axial length of them. Four groups of thermal-fields with different outlet-water temperature are calculated by using ANSYS multi-physical software. The calculation results of temperature of measurement-point between up-layer and down-layer bars in stator are partly supported by the measurement data. And the relatively error between the heat taken by cooling-water and the heat generated by the stator bar is always less than 5%.

关键词： Stators

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Influences of temperature on Space Charge in Gas-to-Liquid Oil-Impregnated Paper 7

Influences of temperature on Space Charge in Gas-to-Liquid O...

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7th IEEE International Conference on High Voltage Engineering and Application, ICHVE 2020

作者： Zhou, Yuanxiang Huang, Xin Zhang, Ling Zhang, Yunxiao Zhou, Zhongliu Teng, Chenyuan China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Department of Electrical Engineering Beijing China

ISBN: (纸本)9781728155111

Gas-to-liquid (GTL) transformer oil has been on trial in converter transformers. However, its influence on the space charge characteristic is not clear. This work aims at exploring space charge characteristics of GTL oil at different temperatures as well as comparing with commercial naphthenic oil (KI50X). Space charge distribution during the polarization and the dissipation process in the GTL oil-impregnated paper at different temperature was measured by the pulse electroacoustic method (PEA), which were contrasted with those of the KI50X oil-impregnated paper. Results illustrated that high temperature accelerated the injection and migration of charge carriers in the oil-impregnated paper. And the polarity of the accumulated charge in the vicinity of anode changed from positive to negative with the increase of temperature. It was perceived that oil-paper conductivity and carrier mobility grew with the increase of temperature, resulting in the easier migration of injected charge to another electrode. Furthermore, the space charge dissipation rate in the GTL oil-impregnated paper is lower than that in the naphthenic oil-impregnated paper at the same temperature. Thus, a longer time interval of tests or switch operation in the factory test and operation process may need if GTL oil is used rather than naphthenic oil. © 2020 IEEE.

关键词： Electric space charge

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Research on the prediction-model of the surface-temperature of large oil-immersed power transformer

Research on the prediction-model of the surface-temperature ...

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

ISBN: (纸本)7506274078

In order to detect the abnormal temperature of large oil-Immersed power transformer earlier, this paper presents a new prediction-model of surface-temperature for the transformer to predict the normal surf ace-temperature. And to compare the difference between the predicted value and the measured value can judge If the condition of the transformer Is fit to operate. The model parameters are estimated from the field data by using the Partial-Least-Square method, which overcomes the instability of results estimated by using the traditional Least-Square method. Furthermore, the appropriate amount of data for the parameter estimation was decided according to the principle of Heat Transfer and the characteristics of the predicted deviation, such as mean, variance and normal distribution. The prediction model is verified from the accuracy of results predicted with one year of field data.

关键词： Electric transformers

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A Joint Prediction Method of Multi-state Variables for High-Voltage Cables Based on GRU 10th

A Joint Prediction Method of Multi-State Variables for High-...

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10th Frontier Academic Forum of Electrical Engineering, FAFEE 2022

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

ISBN: (纸本)9789819934034

In order to carry out risk warning for high-voltage cable transmission system and realize differentiated operation and maintenance decision-making, it is necessary to carry out time series prediction for online monitoring state quantities of high-voltage cables such as load current, partial discharge, and grounding circulating current. Therefore, a joint prediction method for multi-state variables of high-voltage cables based on Gate Recurrent Unit (GRU) is proposed. Taking the online monitoring state quantities of a certain area in central China in May as the analysis data set, a GRU network is built to predict the sequence of multi-state quantities, compared with different models. Taking the phase A load current of a node of the cable as an example to carry out state prediction, the results show that compared with the Long Short Term Memory (LSTM) neural network, back-propagation neural network (BPNN), and Auto Regressive Integrated Moving Average (ARIMA) model, the accuracy of the sequence prediction model based on GRU is Higher. When predicting for 5 min, the MAE and RMSE are 1.94 and 2.65 A, respectively, with the MAPE of 0.54%. When predicting for 30 min, the MAE and RMSE are 9.81 and 15.36 A, respectively, with the MAPE of 2.89%. When predicting for 1 h, the MAE and RMSE are 17.05 and 27.47 A, respectively, with the MAPE of 4.91%. The GRU model performs better due to the suppression on over-fitting of training data with simpler model structure. © Beijing Paike Culture Commu. Co., Ltd. 2023.

关键词： Forecasting

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