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4th International Symposium on Insulation and Discharge Computation for power equipment, IDCOMPU 2023

作者： Zhou, Yuanxiang Dai, Yasong Chen, Jianning Li, Yuhang Hou, Xuzhao Zhang, Zhen State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing100084 China The Wind Solar Storage Division of State Key Laboratory of Power System and Generation Equipment School of Electrical Engineering Xinjiang University Urumqi830047 China

ISBN: (纸本)9789819974047

Long-term operation and switching of transformer on-load tap-changers can cause degradation and deterioration of the main contact material, even leading to contact arcing damage in severe cases. However, the arcing mechanism of the main contact during the switching has not been clarified yet. A magneto-hydrodynamic simulation method of main contact arcing has been proposed. The geometry of the main contact in transformer oil is simplified, and the simulation model of the arc temperature field of the main contact in transformer oil coupled with electric, magnetic, thermal and fluid fields is proposed. The dynamic evolution of the arc temperature has been investigated at peak currents of 2100 A, 1500 A, 600 A and 300 A, respectively. The results show that with the increase of the spacing between contacts, the temperature at arc core rises rapidly and then decreases slowly, and the temperature can reach 50177 K at 2100A. Due to the electron bombardment at the anode surface, the temperature at anode surface is higher than that at cathode surface under different chopped currents. The highest temperatures at anode and cathode surface can reach 4142.5 K and 4081.7 K respectively. © Beijing Paike Culture Commu. Co., Ltd 2024.

关键词： Deterioration

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Condition Evaluation of power Cables Based on BiLSTM with Siamese Attention

Condition Evaluation of Power Cables Based on BiLSTM with Si...

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2023 Panda Forum on power and Energy, PandaFPE 2023

作者： Lin, Menglong Chen, Jianning Zhou, Yuanxiang Pan, Zehua Tsinghua University State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Beijing China Beijing Electric Power Research Institute State Grid Beijing China

ISBN: (纸本)9798350321173

The fast and accurate state evaluation of cable plays an important role in the safe and reliable operation of power system. Thus a high-voltage cables condition evaluation model based on siamese-attention bidirectional long short-term memory (SA-BiLSTM) is proposed in this paper. First, the attention mechanism was used to optimize the BiLSTM network, which can complete parallel training while obtaining global information. then the optimized network was adopted to build a siamese neural network framework, realizing data classification by calculating the Euclidean distance between feature vectors. Finally, the model was trained and tested through the online monitoring data of high-voltage cables from engineering. The results showed that the accuracy rate, precision, recall rate, F1 score and Matthews correlation coefficient of the SA-BiLSTM model was increased at least by 7.92%, 11.79%, 11.41%, 12.04%, and 20.90%, respectively, compared with other models. © 2023 IEEE.

关键词： Long short-term memory

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The harmonic characteristics analysis of offshore wind farms transmitted by the submarine cable based on time domain simulation 6

The harmonic characteristics analysis of offshore wind farms...

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2021 6th International Symposium on Advances in Electrical, Electronics and Computer Engineering, ISAEECE 2021

作者： Li, Jingyi Yang, Jianjun Shi, Zhaohui Wang, Ke Li, Haozhi Xie, Xiaorong Li, Fangfeng Key Laboratory of Far-shore Wind Power Technology of Zhejiang Province Hangzhou Zhejiang311122 China State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Haidian District Beijing100084 China

The harmonic amplitude may exceed the limit when the large scale of wind farm is connected to the weak AC system through AC submarine cable. The harmonic with high amplitude will endanger the safety of power equipment, and even affect the normal integration of large-scale wind farm. This paper takes an actual offshore wind power connected to the system through AC submarine cable as an example. On the basis of building the model of the system in the PSCAD/EMTDC simulation software. The simulation calculation is systematically carried out. The effect of multiple factors on the harmonic characteristics is analyzed. The preliminary explanation for the harmonic amplitude out of limit is given for the actual large scale of wind farm connected to the weak AC system through AC submarine cable. © Published under licence by IOP Publishing Ltd.

关键词： Time domain analysis

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DC Bias Elimination and Soft Switching in Transient state of Dual-Active-Bridge DC-DC Converter 48

DC Bias Elimination and Soft Switching in Transient State of...

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48th Annual Conference of the IEEE Industrial Electronics Society, IECON 2022

作者： Wang, Zhe Li, Chi Liu, Jiye Zheng, Zedong Tsinghua University State Key Lab of Control and Simulation of Power Systems and Generation Equipments Beijing China

ISBN: (数字)9781665480253

ISBN: (纸本)9781665480253

Dual active bridge is a promising isolated bidirectional DC/DC converter which has attracted more and more attention due to its advantages of zero-voltage switching, great voltage regulation ability, high power density, and fast dynamic response. However, the DC bias problem is seldom mentioned, which may lead to system instability and decreased efficiency. Besides, whether the converter can realize soft switching in the dynamic process is unclear. This paper proposed a novel phase-shift loading mode which can not only realize the DC bias elimination but also achieve zero voltage switching (ZVS) during a transient state. Finally, a 4.5 kW prototype is built and experimental results are provided to verify the conclusion. © 2022 IEEE.

关键词： Zero voltage switching

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Modeling and simulation analysis of dual-rotor vibration system with multiple faults

Modeling and simulation analysis of dual-rotor vibration sys...

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Society for Machinery Failure Prevention Technology Conference 2018: Intelligent Technologies for equipment and Human Performance Monitoring, MFPT 2018

作者： Yang, Yizhou Liu, Chao Jiang, Dongxiang Yang, Wenguang State Key Lab. of Control and Simulation of Power Systems and Generation Equipment Department of Thermal Engineering Tsinghua University Beijing100084 China

Dual-rotor system is an important rotor form in rotating machinery like gas turbine engine. Its complex structure results in rich dynamical behaviors and more probability to failure. The modeling and simulation of the dual-rotor system can help to understand its dynamic characteristics and provide theoretical support for the design, operation and maintenance. In this paper, a dynamic model of a dual-rotor system with multiple rotor faults is established. The dual-rotor vibration model without any fault is built by finite element method, where the two shafts are connected by an inter-shaft bearing and nonlinear models of rolling element bearing and squeeze film damper are considered. The numerical integration method of Newmark-β is used to obtain the steady-state vibration response of the system. Then rotor faults are introduced to the system model, including unbalance, misalignment, looseness and rub-impact. The steady-state responses of single faults in the dual-rotor system are analyzed and typical fault features are obtained. Then coupling characteristics between different rotor faults, and the influences of the squeeze film dampers on the dynamic characteristics and fault features of the system are studied. © 2018 Proceedings of the 9th International Symposium on Imprecise Probability.

关键词： Rotating machinery

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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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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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Hierarchical Dispatch Method for Integrated Heat and power systems Based on a Feasible Region of Boundary Variables

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CSEE Journal of power and Energy systems 2020年第3期6卷 543-553页

作者： Tuo Jiang Yong Min Weichun Ge Lei Chen Qun Chen Fei Xu Huanhuan Luo Guiping Zhou State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical EngineeringTsinghua UniversityBeijing 100084China State Grid Liaoning Electric Power Supply Co.Ltd. Shenyang 110000China Department of Engineering Mechanics Tsinghua UniversityBeijing 100084China

Fully utilizing the flexibility provided by a district heating system(DHS)can promote wind power accommodation for an electric power system(EPS).However,for privacy or communication reasons,existing power and heat dispatch methods are not suitable for practical *** this paper,a general math formulation of the hierarchical dispatch method is proposed to coordinate EPS and DHS operators based on the feasible region of boundary variables(FRBV),and a method based on the simplicial approximation approach is proposed to obtain a conservative FRBV approximation of a DHS.A simulation based on a real 41-node DHS is constructed to determine the factors that may impact the boundaries of the FRBV,and then the performance of the simplicial approximation approach is displayed by visualizing the approximation process for the FRBV,and finally three dispatch methods are compared to show the advantages of the proposed hierarchical dispatch method.

关键词： District heating system feasible region hierarchical dispatch method integrated heat and power system simplicial approximation approach

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Experimental research of the upward leader inception from transmission line

Experimental research of the upward leader inception from tr...

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2011 7th Asia-Pacific International Conference on Lightning, APL2011

作者： Zeng, Rong Li, Zhizhao Yu, Zhanqing Zhuang, Chijie State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing 100084 China

ISBN: (纸本)9781457714665

Electro-Geometric Model (EGM) has been applied widely all over the world to evaluate the lightning shielding failure of transmission line. But with the increase of operation voltage to 1000 kV and tower height to more than 100 meters, some shortcomings of the traditional EGM model were found by many researchers. Leader Progression Model (LPM) was proposed to solve these problems. But some fundamental works, such as when the upward leader initiates and how it propagates, is still indistinct. An experiment was designed and implemented in this paper to simulate the electric field circumstance near the test transmission line while the lightning downward leader approached. The upward leader from the test transmission line was clearly observed. The inception voltage and characteristics was analyzed. The streamer and leader initiated from the ground wire and conductor bundle were compared. The experiment results show that the leader initiating from the ground wire is more active in the inception stage. The velocity of the upward leader acquired is about 1.2-3.0 cm/μs. © 2011 IEEE.

关键词： Electric lines

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High resistance grounding fault feeder detection in a resonant grounding system based on transient current correlation coefficient comparison 8

High resistance grounding fault feeder detection in a resona...

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8th Renewable power generation Conference, RPG 2019

作者： Cui, Xin Wang, Bin Dong, Xinzhou Key Lab of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing100084 China

ISBN: (纸本)9781839531255

Because the fault characteristics is not obvious, the high resistance grounding fault feeder selection in a resonant grounding system has always been a hot and difficult problem in the field of power system protection. To solve this problem, the expressions of the transient zero sequence current of each feeder under over-damping and under-damping conditions are obtained based on the transient equivalent circuit of high resistance grounding fault in a resonant grounding system. The correlation degree of the transient zero sequence current between any two feeders is analysed by using the correlation coefficient method, so as to realize the fault feeder selection for high resistance grounding fault. simulation results of PSCAD software show that this method is not affected by transition resistance, initial phase angle of fault, and has high accuracy and reliability. © 2019 Institution of Engineering and Technology. All rights reserved.

关键词： Damping

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