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International Conference on power Electronics (ICPE)

作者： Wenhao Xie Shiqi Ji Zhengming Zhao Xin Mo Department of Electrical Engineering State Key Laboratory of Control and Simulation of Power System and Generation Equipment Tsinghua University China Tsinghua Sichuan Energy Internet Research Institute China

Compared to Si IGBTs, SiC MOSFETs can reduce switching losses, achieve higher switching frequencies and enable smaller converter size. However, due to the high dv/dt of SiC MOSFETs, certain topologies, such as two SiC MOSFETs in a phase-leg configuration, are highly sensitive to crosstalk, which can slow down switching speed and even reduce gate oxide’s lifetime. In this paper, an accurate model of crosstalk is established by considering the impacts of both dv/dt and di/dt in the power loop. The proposed model can simulate the gate-source voltage on bare die of SiC MOSFETs, allowing for a more accurate evaluation of the impact of crosstalk. Model verification is implemented using a double pulse test (DPT) platform and a gate driver with active miller clamp technology. key parameters of the model are extracted from both 3D simulation models and measurement experiments. The DPT waveform of power loop is used as the excitation source in the simulation, and the simulated gate-source waveform shows good agreement with the experimental waveform. Based on the model, parameter sensitivity analysis is performed, and suggestions for improving crosstalk suppression are proposed.

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A Novel Structure Design of Iron Core for power Transformers Considering Joints Forms and Magnetostriction.

A Novel Structure Design of Iron Core for Power Transformers...

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International Conference on Magnetics (INTERMAG)

作者： J. Li S. Wang H. Gao M. Liu J. Hong State Key Laboratory of Control and Simulation of Power System and Generation Equipments Tsinghua University Beijing China State Key Laboratory of Reliability and Intelligence of Electrical Equipment Hebei University of Technology Tianjin China

Body: power transformers and reactors are important devices in power transmission systems. But their cores and windings could produce vibration and acoustic noise by magnetostrictive effect, Maxwell electromagnetic stress and Lorentz force. Noise has become a bad environmental pollution source in some situations, and its vibration and noise reduction has become an urgent problem need to be solved. The shapes, materials, magnetostriction and joints forms of iron cores, the limitations of test, modeling, and experimental measurement of vibration and noise characteristic, are all the difficult reasons to analyze the vibration and acoustic noise of transformers and reactors. 1. The magnetostrictive modeling can be divided into two steps based on the magnetic field force and materials deformation, so the magnetic field force will be fed into the structural finite element with Maxwell electromagnetic force produced on the interface between the iron core and the air to calculate the deformation of the magnetic materials and to make the model more general and consistent. In order to fully verify the correctness of the model in the magnetostrictive analysis, and to ensure the simplicity of test and avoid unnecessary interference factors, the most simple magnetostriction tests will be carried out by using a single closed circle or rectangular electrical steel sheet, as shown in Fig. 1(a). The tests will measure the relationship between magnetostriction and magnetic field of different magnetic materials, different saturations, different sizes and different shapes. 2. The joint is a necessary form for the stacking of large transformer iron cores, and the main joint form is the step jiont at present. The introduction of the joints causes the magnetic force lines to flow through the different laminations and to make the local magnetic field complicated. From simple to complex process is adopted in this paper, and the verification is gradually complicated. Based on the study of a

关键词： Magnetics Conferences

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Ultra-short-term solar power forecasting based on a modified clear sky model

Ultra-short-term solar power forecasting based on a modified...

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第三十九届中国控制会议

作者： Yuan Ma Xuemin Zhang Shengwei Mei Zhao Zhen Rui Gao Zijie Zhou State Key Lab of Control and Simulation of Power Systems and Generation Equipments （Dept of Electrical Engineering Tsinghua University）

The ultra-short-term prediction of photovoltaic power system is of great significance to the safe operation of power ***,the daily and annual periodicity of solar radiation brings strong non-stationary to the photovoltaic power series,which makes it difficult to predict the photovoltaic power *** order to overcome the problem that the detailed clear sky model relies on a large number of plant parameters,this paper proposes a prediction algorithm based on a modified clear sky ***,historical data and geographical location of a certain site are utilized to build a modified clear sky model,then the theoretical clear sky power curve fitted by the modified clear sky model are divided by the actual historical power output to get a stabilized time series,finally the method of "online update" is adopted to forecast PV plant power output in the ultrashort-term time horizon（0-4 h）.The test results of a photovoltaic power station in Ningxia show that the proposed model can reduce the prediction error of the 4 th hour to about 3%.

关键词： Clear sky model stabilization photovoltaic power generation ultra-short-term prediction

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Green roadmap choice for coupled system of power and urban heating: quick win or long-term strategy?

Green roadmap choice for coupled system of power and urban h...

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IEEE General Meeting power& Energy Society

作者： Yisha Lin Ying Qiao Zongxiang Lu Jin Li State Key Lab of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing China Wind Power Technology Center State Grid Gansu Electric Power Company Lanzhou China

ISBN: (数字)9781728155081

ISBN: (纸本)9781728155098

Cleanliness of energy system requires both NO x reduction due to urgent air pollution control and CO 2 cutting due to long-term climate change pressure. In the urban heating sector, quick-win plans use to be popular that focus on the NO x reduction by replacing untreated scattered coal fired boilers to natural gas or combined heat and power generators (CHPs). Meanwhile, in the electrical sector, all these fossil fuel generators should be cut down in the long-term decarbonization process. There should be a need for coordination of short- and long-term targets, because two energy supply sectors are believed to work in a coupled way in the future. A three-layered collaborative planning model is proposed in this paper: the top layer focuses roadmap economic evaluation; the middle layer applies coupled production simulation aiming at verifying energy balance; and the bottom one checks real-time operational feasibility. Pathways are made from 2020 to 2040 based on Hebei, China. Results indicate that the pathway with quick win will have delayed construction of renewable power, resulting the slow process in emission control. The long-term strategy scheme greatly promotes the renewables for supply in both sectors, but the close operational link forces the decoupling, leading to rebound on emission and operation cost on decentralized heating for the long-term future. In conclusion, the tradeoff pathway, reducing CO 2 emission as much as possible with NO x emission controlled to acceptable level, is recommended with good performance on emission control and economy.

关键词： Cogeneration Process control Production Air pollution Generators Real-time systems Planning

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power transformer condition assessment by on-line monitoring and trend analysis

Power transformer condition assessment by on-line monitoring...

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IASTED International Conference on power and Energy systems and Applications, PESA 2012

作者： Xie, Qijia Gao, Shengyou Zhang, Hailong Dai, Wen Ruan, Ling Nie, Dexin Lu, Wenhua Key Laboratory of High-Voltage Field-Test Technique of SGCC Hubei Electric Power Testing and Research Institute Wuhan China State Key Lab of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing China State Grid Electric Power Research Institute Wuhan China School of Electrical Engineering Wuhan University Wuhan China

power transformer condition assessment is the basi of condition-based maintenance and plays a very important role in carrying assets management and risk assessment for power system. As the heart of transmission and transformation system, power transformer's condition has close relation with many factors, such as the production quality of itself, operation environment and so on. This paper analyzes some variables which could represent the transformer's condition, including the data from preventative test, factory test and commission test, diagnostic test, on-line detection and monitoring, routine inspection, operation history, family defection and environment information. Some parameters which have representation are chosen as the condition variables. Artificial neuron network (ANN) and Dempster-Shafer (D-S) evidence theory are adopted to form the multiparameter information fusion condition assessment model. Besides the static value, the change trends of some parameters are considered as an independent evidence section. Cooperating with on-line monitoring, it will be helpful to improve the accuracy and efficiency of condition assessment.

关键词： power transformers

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The Actual Operation of Transmission Line and Evaluation of the Reclosing Time of Reclosure

The Actual Operation of Transmission Line and Evaluation of ...

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2017 International Conference on Mechanical and Mechatronics Engineering(ICMME2017)

作者： Rui-ming OU Gun YANG Zhan-qing YU Jin-bo WU Shui-ming CHEN Hong-jun ZHEN Qingyuan Power Supply Bureau of Guangdong Grid Company State Key Lab.of Control and Simulation of Power Systems and Generation Equipment Department of Electrical EngineeringTsinghua University

In this paper,the actual trip of typical transmission line is *** includes the trip frequency of transmission lines and the tripping frequency caused by lightning,seasonal distribution characteristics of transmission line trip,and the success rate of reclosing on the transmission *** this paper,the probability of the occurrence of the trip again is evaluated based on the duration of ground lightning *** the increase of the time of reclosure,the probability of the occurrence of the trip will *** this calculating method,the average probability of tripping of reclosure decreased significantly during a ground lightning stroke process,when the reclosing time t0 is 1 s.

关键词： Trip of transmission line Trip caused by lightning Reclosing time of reclosure Probability of tripping of reclosure

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INFLUENCES OF BREAKDOWN CHARACTERISTICS OF DISCONNECT SWITCH GAP ON RESIDUAL VOLTAGE

INFLUENCES OF BREAKDOWN CHARACTERISTICS OF DISCONNECT SWITCH...

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The ⅪⅩ International Conference on Gas Discharges and Their Applications

作者： YUE GONGCHANG GUAN YONGGANG LIU WEIDONG CHEN WEIJIANG LI ZHIBING State Key Lab of Control and Simulation of Power System and Generation Equipments Department of Electrical EngineeringTsinghua University State Grid Corporation of China China Electric Power Research Institute

The very fast transient overvoltages(VFTO) are generated during operation of disconnect switch (DS) of gas insulated switchgear(GIS). After the opening operation of DS,the load side busbar is left at a residual *** residual voltage is determined by the opening phase and the breakdown characteristics of SF6 gap of DS. This study obtains the breakdown characteristic of the test DS,including the dielectric strength recovery speed and polarity effect factor of gap of testing *** the stochastic property of DS opening phase,the opening process of DS is simulated by computer under different dielectric strength recovery speeds and polarity effect *** results show that the dielectric strength recovery speed and polarity effect factor have big influences over the residual *** proper value of dielectric strength recovery speed and polarity effect factor could make the residual voltage minor

关键词： simulation INFLUENCES OF BREAKDOWN CHARACTERISTICS OF DISCONNECT SWITCH GAP ON RESIDUAL VOLTAGE

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The Method for Evaluating the Reclosing Time of Reclosure Based on Lightning Parameters

The Method for Evaluating the Reclosing Time of Reclosure Ba...

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2017 International Conference on Mechanical and Mechatronics Engineering(ICMME2017)

作者： Gun YANG Zhan-qing YU Hong-jun ZHEN Chao SU Shui-ming CHEN Rong ZENG Jin-liang HE State Key Lab.of Control and Simulation of Power Systems and Generation Equipment Department of Electrical EngineeringTsinghua University Qingyuan Power Supply Bureau of Guangdong Grid Company

The fault of transmission line is mostly caused by lightning,and a ground lightning stroke process is often accompanied by multiple *** duration of ground lightning stroke are also *** this paper,a method for evaluating the reclosing time of reclosure based on lightning parameters is *** addition,this paper also gives an expression for the cumulative rate of the duration of ground lightning stroke,and an expression for probability distribution of the amplitude of lightning current in Guangdong *** also proposed a method for calculating the probability of tripping of *** this calculating method,the average probability of tripping of reclosure is less than 1/10000 during a ground lightning stroke process,when the reclosing time t0 is greater than 1.012 s.

关键词： Ground lightning stroke Lightning parameters Reclosing time of reclosure Probability of tripping of reclosure

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Electrical Tree Evolution under DC Voltages and Its Differences from AC Trees in Silicone Rubber

Electrical Tree Evolution under DC Voltages and Its Differen...

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Conference on Electrical Insulation and Dielectric Phenomena, (CEIDP)

作者： Yunxiao Zhang Yuanxiang Zhou Ling Zhang Chenyuan Teng Zhongliu Zhou Meng Huang State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing China The Wind Solar Storage Division of State Key Laboratory of Power System and Generation Equipment School of Electrical Engineering Xinjiang University Urumqi China State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University Beijing China

Electrical tree is one of the major issues for insulation failure in high-voltage direct current (HVDC) cable. In this paper, electrical tree initiation and growth characteristics of silicone rubber (SIR) are studied by optical tree observation system under DC and AC voltage with varied temperature. Moreover, tree channels are pictured and analyzed by 3D fluorescence imaging technology. Results show that the average tree initiation voltage, whether DC or AC, decreases exponentially with increasing temperature. However, the initiation voltage under positive DC voltages is much higher than that under AC voltages. AC tree growth pattern could be roughly divided into two modes: bush-like growing pattern and pine-like growing pattern, while DC trees stop growing after voltage stabilizes. 3D fluorescence tests show that DC tree branches are sparser and the channels are thinner. Based on the trap theory, mechanism of DC electrical tree in SIR is clarified. It is believed that different charge transport dynamics are the main reason for the differences in electrical tree behavior under DC and AC voltages.

关键词： Three-dimensional displays Temperature Shape HVDC transmission Conferences Fluorescence Space charge

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Distributionally Robust Dispatch for power system with Advanced Adiabatic Compressed Air Energy Storage Considering Frequency Security

SSRN

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SSRN 2024年

作者： Liu, Hanchen Chen, Laijun Cui, Sen Chen, Siyuan Mei, Shengwei State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing100084 China

In response to climate change and the need to decrease carbon emissions, the penetration of renewable energies into power grids is growing dramatically. However, the high intermittence and low inertia of renewable energy pose significant risks to frequency security. The advanced adiabatic compressed air energy storage (AA-CAES) is a promising solution to enhancing grid frequency security due to its flexible and high inertia properties. Therefore, based on distributionally robust optimization, this paper proposes a dispatch strategy with the participation of AA-CAES to enhance frequency security. Firstly, a dispatch-friendly model of AA-CAES is proposed and can reflect the impacts of the part-load features on the dis-/charging efficiencies and capacities. Subsequently, a frequency response model with AA-CAES is presented to establish frequency security constraints, ensuring compliance with minimum inertia and maximum frequency deviation requirements. Furthermore, to cope with the randomness of renewable energy, this proposed model is formulated as a distributionally robust optimization problem with a "min-max-min" structure. In the day-ahead stage, the optimal on/off schedules for generators and AA-CAES can be determined according to the worst probability distribution in the second stage for providing sufficient grid inertia. In the intra-day stage, the generation and AA-CAES can be adjusted to minimize the frequency deviation. Finally, numerical studies are tested on the modified IEEE-39 bus system. The simulation results demonstrate the validity and feasibility of the proposed strategy with AA-CAES in supporting grid frequency security. © 2024, The Authors. All rights reserved.

关键词： Wind power

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