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2021 Annual Meeting of CSEE Study Committee of HVDC and power Electronics, HVDC 2021

作者： Liu, Guowei Guo, Peiqian Yuan, Zhichang Zhao, Yuming Shenzhen Power Supply Corporation Shenzhen China Department of Electrical Engineering State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing China

ISBN: (纸本)9781839537035

With effective properties, a resistive-type superconducting fault current limit (R-SFCL) has become an effective device to restrain DC-side bipolar short fault currents in multilevel modular converter multiterminal DC systems (MMC-MTDCs). However, due to the resistance-energy accumulation-dependent characteristics of the R-SFCL device, the fault durations and different fault current values will produce various output resistances at each fault stage, and the related coordinated protection and control strategy needs to be adjusted accordingly. Therefore, in the first part of this paper, we analysed the DC side short circuit current mechanism and the fault current restraint characteristics of R-SFCLs. Subsequently, to verify the above analysis, the R-SFCL-based four-terminal MMC-MTDC with DC bipolar short fault modelling and simulation are presented in the next section. Finally, based on the above analysis and research, the advanced DC bipolar fault control and protection strategies of the R-SFCL-based MMC-MTDC system are discussed to promote further study of coordinated and protection control and the application of R-SFCLs in subsequent engineering applications. © 2021 IET Conference Proceedings. All rights reserved.

关键词： Timing circuits

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Failure analysis of fan mill in thermal power plant 68

Failure analysis of fan mill in thermal power plant

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68th Society for Machinery Failure Prevention Technology Conference: Technology Solutions for Affordable Sustainment, MFPT 2014

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

Fan mill is an important device in thermal plants, which supply coal power to boiler. Crack failures recently occurred in pulverizing wheels of fan mills in a power plant in China. The cracks happens in quite a few pulverizing wheels and they affect the normal operation. To find out the root cause of the cracks, Finite Element Analysis (FEA) of the pulverizing wheel is carried out in this work. The assembly with real dimensions is modelled to calculate the concentrated stress and strain with centrifugal load, driving load, and operational temperature taken into account. Contact effects are included in the finite element model as well as nonlinear material property. Based on the analysis, the crack causes are determined: (i) the initial stress exceeds the yield limit in normal operational condition, resulting low safety coefficient;(ii) the stress increases significantly in the worn pulverizing wheel, where the risk of failure is greatly increased.

关键词： Cracks

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Wind power generation Capacity Evaluation Based on Correlation Analysis of Adjacent Wind Farms

Wind Power Generation Capacity Evaluation Based on Correlati...

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2021 IEEE Sustainable power and Energy Conference, iSPEC 2021

作者： Sun, Shuxin Qiao, Ying Lu, Zongxiang Ma, Yanhong Tsinghua University State Key Lab of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Beijing100084 China State Grid Gansu Electric Power Company Wind Power Technology Center Lanzhou730050 China

ISBN: (纸本)9781665414395

Accurate assessment of the power generation capacity of the wind farm is the key basis for incorporating it into power system scheduling and other optimizing operation activities. Traditional evaluation methods, such as benchmarking wind turbine method, have higher requirements for input data, but many wind farms in operation for many years are difficult to meet such data conditions. A new power generation capacity evaluation method based on correlation analysis of adjacent wind farms is proposed in this paper. Meteorological data and power of adjacent wind farms are used as replaced input data based on correlation analysis between the target farm with its adjacent farms. First, anticipate wind speed data and then construct the wind power curve with three different neural networks to evaluate power generation capacity. Afterwards, adjacent wind farms are used as data sources to fit the power data of the target wind farm with the application of influence radius method, inverse square distance method and bilinear interpolation method. Finally, combined with data in the actual case, investigate the advantages and disadvantages of different methods in the evaluation of power generation capacity. © 2021 IEEE.

关键词： Time delay

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Modelling and harmonic analysis of metro traction power supply system 18

Modelling and harmonic analysis of metro traction power supp...

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18th International Conference on AC and DC power Transmission, ACDC 2022

作者： Guo, Peiqian Zhao, Yuming Liu, Guowei Yuan, Zhichang Wu, Aijun Wang, Yuxuan Jiang, Zhilin Xiang, Miaoyi State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing China Shenzhen Power Supply Corporation Shenzhen China

ISBN: (数字)9781839537615

ISBN: (纸本)9781839537615

The large number of nonlinear loads used in urban metro rail traction grids distorts the voltage and current on the load side, then generates harmonics. The resulting capacitive characteristic harmonics current component provides feedback to the power grid, thus causing additional power losses and equipment damage. To solve this power quality problem, a detailed dynamic simulator of the metro traction power supply system is developed, which includes the corresponding 24-pulse rectifier and low-voltage power distribution system. Based on the established simulator, a study of the harmonic content and characteristics research of the 24-pulse rectifier and low-voltage electricity-consuming equipment are performed. In combination with the digital simulator, we presented and disused the lower-order frequency harmonic currents of the 35kV AC bus exhibiting capacitive characteristics. The results lay a technical foundation for harmonic equivalent impedance calculation and harmonic current suppression of the metro traction power supply system. © ACDC 2022. All rights reserved.

关键词： Simulators

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Characteristics calculation and pattern recognition for partial discharge of cable joint

Characteristics calculation and pattern recognition for part...

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2014 International Conference on Communication Technology and Application, CTA 2014

作者： Xia, Y.F. Gui, J.F. Chen, X.Y. Gao, S.Y. Huang, J.H. Lin, J.H. Dongguan Power Breuse of Guangdong Grid China School of Electrical Engineering Beijing Jiaotong University China Department of Electrical Engineering Tsinghua University State Key Lab of Control and Simulation of Power Systems and Generation Equipments China

ISBN: (纸本)9781845649302

For PD pattern recognition, six kinds of typical cable fault models are made and tested. Characteristics are calculated from test data. Multiple statistical characteristics of PD distribution map are calculated and pattern vectors are formed. Artificial neural network is trained for recognition. Through the selection and adjustment of characteristics and network parameters, recognition effect with satisfactory result is obtained. © 2014 WIT Press.

关键词： Partial discharges

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A large-scale reactive power optimization method based on gaussian penalty function with discrete control variables

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Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering 2013年第4期33卷 68-76页

作者： Li, Zhigang Wu, Wenchuan Zhang, Boming Guo, Qinglai State Key Lab of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Haidian District Beijing 100084 China

Reactive power optimization with discrete control variables can be formulated as a mixed-integer nonlinear programming problem, which is a typical NP-hard problem in mathematics. This paper proposed a Gaussian penalty function based approach to handle discrete variables, in which the discrete variables were relaxed to continuous variables. The properties of the optimization model with Gaussian penalty function, as well as how it could be affected by parameters, were discussed. Then a practical algorithm combining nonlinear interior point method and a heuristic parameters tuning strategy was developed to solve the optimization problem. Finally, numerical experiments were taken on different systems, including IEEE standard systems and several real power systems with varying scales, to verify the robustness and practicability of the proposed method. © 2013 Chinese Society for Electrical Engineering.

关键词： IEEE Standards

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Optimal Auxiliary Frequency control of Wind Turbine Generators and Coordination with Synchronous Generators

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CSEE Journal of power and Energy systems 2021年第1期7卷 78-85页

作者： Ming Sun Yong Min Lei Chen Kaiyuan Hou Deming Xia Hangyin Mao State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical EngineeringTsinghua UniversityBeijing 100084China with Northeast Branch of State Grid Corporation of China Shenyang 110180Liaoning ProvinceChina with State Grid Zhejiang Electric Power Co.LTD. Hangzhou 310007Zhejiang ProvinceChina

Auxiliary frequency control of a wind turbine generator(WTG) has been widely used to enhance the frequencysecurity of power systems with high penetration of renewableenergy. Previous studies recommend two types of control schemes,including frequency droop control and emulated inertia control,which simulate the response characteristics of the synchronousgenerator (SG). This paper plans to further explore the optimalauxiliary frequency control of the wind turbine based on previousresearch. First, it is determined that the virtual inertia control haslittle effect on the maximum rate of change of frequency (MaxROCOF)if the time delay of the control link of WTG is taken intoconsideration. Secondly, if a WTG operates in maximum powerpoint tracking (MPPT) mode and uses the rotor deceleration forfrequency modulation, its optimal auxiliary frequency control willcontain only droop control. Furthermore, if the droop control isproperly delayed, better system frequency response (SFR) willbe obtained. The reason is that coordination between the WTGand SG is important for SFR when the frequency modulationcapability of the WTG is limited. The frequency modulationcapability of the WTG is required to be released more ***, when designing optimal auxiliary frequency controlfor the WTG, a better control scheme is worth further study.

关键词： Frequency droop control power system frequency security rate of change of frequency(ROCOF) virtual inertia control wind turbine generator auxiliary frequency control

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Risk Assessment with Generic Energy Storage under Exogenous and Endogenous Uncertainty

Risk Assessment with Generic Energy Storage under Exogenous ...

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2022 IEEE power and Energy Society General Meeting, PESGM 2022

作者： Qi, Ning Cheng, Lin Wan, Yuxiang Zhuang, Yingrui Liu, Zeyu State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing100084 China Tianjin University China

ISBN: (数字)9781665408233

ISBN: (纸本)9781665408233

Current risk assessment ignores the stochastic nature of energy storage availability itself and thus lead to potential risk during operation. This paper proposes the redefinition of generic energy storage (GES) that is allowed to offer probabilistic reserve. A data-driven unified model with exogenous and endogenous uncertainty (EXU & EDU) description is presented for four typical types of GES. Moreover, risk indices are proposed to assess the impact of overlooking (EXU & EDU) of GES. Comparative results between EXU & EDU are illustrated in distribution system with day-ahead chance-constrained optimization (CCO) and more severe risks are observed for the latter, which indicate that system operator (SO) should adopt novel strategies for EDU uncertainty. © 2022 IEEE.

关键词： Risk assessment

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Research on Lithium-ion Battery Safety Risk Assessment Based on Measured Information

Research on Lithium-ion Battery Safety Risk Assessment Based...

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2020 IEEE Sustainable power and Energy Conference, iSPEC 2020

作者： Zhou, Xuyan Cheng, Lin Wan, Yuxiang Qi, Ning Tian, Liting You, Feng State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing China Energy Storage System Business Unite Tianjin Lishen Battery Joint-Stock Co. Ltd. Tianjin China

ISBN: (纸本)9781728191645

Lithium-ion batteries have the advantages of high energy density, fast power response, recyclability, and convenient to movement, which are unsurpassed by other energy storage systems. However, safety issues such as thermal runaway of lithium-ion batteries have become the main bottlenecks restricting the development of their extensive applications. In practical applications, the demand for battery energy storage scale and specific energy continues to increase, and the contradiction between battery high safety and battery safety has become increasingly prominent. This paper proposes a lithium-ion battery safety risk assessment method based on online information. Effective predictions are essiential to avoid irreversible damage to the battery and ensure the safe operation of the battery energy storage system before a failure occurs. This paper is expected to provide novel risk assessment method and research idea for the development and design of high-safety battery systems. © 2020 IEEE.

关键词： Lithium-ion batteries

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Travelling wave based single phase grounding protection for distribution system

Travelling wave based single phase grounding protection for ...

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12th IET International Conference on Developments in power System Protection, DPSP 2014

作者： Dong, Xinzhou Wang, Jun Shi, Shenxing Wang, Bin Dominik, Bak Kirby, Brian Yang, Xia State Key Lab of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing 10084 China Alstom Grid Stafford ST174LX United Kingdom

ISBN: (纸本)9781849198349

It is very difficult to correctly identify single-phase-to-ground fault (SFG) in distribution system with neutral non-effectively grounded (NNG). A novel travelling wave based singlephase-to-ground protection is proposed in the paper. The polarity of initial transient current and voltage travelling waves are used to identify the fault direction, and power frequency voltages are used to distinguish SFG from phaseto- phase fault to ensure the reliability of the protection. In the paper, wavelet transforms and module maxima theory was adopted to represent the polarity of travelling waves effectively and construct protection algorithm,. The analysis and simulation demonstrate that the protection is valid.

关键词： Wavelet transforms

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