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Study on dynamic stiffness of supporting structure and its influence on vibration of rotors

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Chinese Journal of Aeronautics 2022年第11期35卷 252-263页

作者： Yongfeng WANG Yanhong MA Jie HONG School of Energyand power Engineering Beihang UniversityBeijing 100083China research institute of Aero-Engine Beijing 100083China

The dynamic response of the rotor depends on not only itself but also the dynamical characteristics of the structures that support it. In this paper, the coupling vibration characteristics of the rotor and supporting structure are studied using one simple rotor-supports model firstly, and then the dynamic stiffness of the typical supporting structure of an aero-engine is investigated in use of both numerical and experimental methods. While, one simulation strategy is developed to include dynamic stiffness of realistic supports in the dynamical analysis of the rotor system. The simulated and tested results show that the dynamic stiffness of the supporting structure not only depends on the structural parameters but also is related to the frequency of the excitation force. The dynamic stiffness is affected by the damping and inertia effect when the excitation frequency is high and closed to the resonance frequency of the support, which may decrease the dynamic stiffness *** resonance frequencies may be induced and the critical speed could be reduced or *** higher vibration response peak and overload of the bearing may also be caused by the varied dynamic stiffness, which needs to be avoided in the design of the rotor-supports system.

关键词： Coupling vibration Critical speed Dynamic stiffness Rotor dynamic Rotor-supports system

Excitation and Detection of Shear Horizontal Waves with Electromagnetic Acoustic Transducers for Nondestructive Testing of Plates

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Chinese Journal of Mechanical Engineering 2014年第2期27卷 428-436页

作者： MA Qingzeng JIAO Jingpin HU Ping ZHONG Xi WU Bin HE Cunfu Electric power research institute of Guangdong power Grid Corporation College of Mechanical Engineering and Applied Electronics Technology Beijing University of Technology

The fundamental shear horizontal（SH0） wave has several unique features that are attractive for long-range nondestructive testing（NDT）. By a careful design of the geometric configuration, electromagnetic acoustic transducers（EMATs） have the capability to generate a wide range of guided wave modes, such as Lamb waves and shear-horizontal（SH） waves in plates. However, the performance of EMATs is influenced by their parameters. To evaluate the performance of periodic permanent magnet（PPM） EMATs, a distributed-line-source model is developed to calculate the angular acoustic field cross-section in the far-field. Numerical analysis is conducted to investigate the performance of such EMATs with different geometric parameters, such as period and number of magnet arrays, and inner and outer coil widths. Such parameters have a great influence on the directivity of the generated SH0 waves that arises mainly in the amplitude and width of both main and side lobes. According to the numerical analysis, these parameters are optimized to obtain better directivity. Optimized PPM EMATs are designed and used for NDT of strip plates. Experimental results show that the lateral boundary of the strip plate has no perceivable influence on SHO-wave propagation, thus validating their used in NDT. The proposed model predicts the radiation pattern ofPPM EMATs, and can be used for their parameter optimization.

关键词： electromagnetic acoustic transducers shear-horizontal waves strip plate nondestructive testing

Review of Learning-assisted power System Optimization

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CSEE Journal of power and Energy Systems 2021年第2期7卷 221-231页

作者： Guangchun Ruan Haiwang Zhong Guanglun Zhang Yiliu He Xuan Wang Tianjiao Pu Department of Electrical Engineering Tsinghua UniversityBeijing 100084China China Electric power research institute Beijing 100192China

With dramatic breakthroughs in recent years,machine learning is showing great potential to upgrade the toolbox for power system *** the strength and limitation of machine learning approaches is crucial to decide when and how to deploy them to boost the optimization *** paper pays special attention to the coordination between machine learning approaches and optimization models,and carefully evaluates how such data-driven analysis may improve the rule-based *** typical references are selected and categorized into four groups:the boundary parameter improvement,the optimization option selection,the surrogate model,and the hybrid *** taxonomy provides a novel perspective to elaborate the latest research progress and *** further compare the design patterns of different categories,and discuss several key challenges and opportunities as *** integration between machine learning approaches and optimization models is expected to become the most promising technical trend.

关键词： Artificial intelligence data-driven deep learning machine learning neural network smart grid

Effect of Thermomechanical Treatment Temperature on Structure and Properties of CFB/M Ultra-High Strength Steel

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Journal of Iron and Steel research International 2010年第4期17卷 66-72页

作者： XU Xue-xia BAI Bing-zhe LIU Dong-yua YUAN Ye Laboratory of Advanced Materials Department of Materials Science and Engineering Tsinghua UniversityBeijing 100084 China Hebei Electric power research institute Shijiazhuang 050021 Hebei China School of Energy and power Engineering North China Electric Power University Beijing 102206 China Northwest Electric power design institute Xi’an 710075 Shaanxi China

Modified CCT diagram of carbide-flee bainite-martensite （CFB/M） ultra-high strength steel was established by applying controlled cooling of small samples. In addition, the influence of thermomechanical treatment tem- perature on the structure and properties was discussed. The experimental results showed that when deformed at 860℃ and below, ferrite transformation occurred due to strain. With the decrease of ausforming temperature, the quantity of ferrite increased and strength and toughness were deteriorated. Therefore, certain information was provided for optimizing technical parameter of ausforming process., firstly, the thermomechanical treatment temperature should not be lower than 860 ℃ in order to avoid ferrite formation induced by deformation; secondly, rapid cooling rate is also significant after deformation in order to avoid ferrite precipitation during subsequent cooling stage.

关键词： thermomechanical treatment carbide-free bainite/martensite (CFB/M) ultra-high strength steel

Parameters Analysis and Operational Area Calculations of VSG Applied to Distribution Networks

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CSEE Journal of power and Energy Systems 2023年第6期9卷 2214-2223页

作者： Zhipeng Lyu Xiaotong Gong Linxu Liu Lan Liu State Grid Shanghai Energy Interconnect research institute Shanghai 200120China Shanghai University of Electric power Shanghai 200090China China Electric power research institute Beijing 100192China

Virtual synchronous generator(VSG)technology is an effective way to realize coordinated energy supply of active distribution networks and comprehensive energy at *** paper starts from the two perspectives of grid-connected operational modes and island operational *** on the mathematical model of VSG,referring to existing grid standards,comprehensively considering its active and reactive-power loop stability and dynamic performance,the influencing factors of the related control parameters K,Dq,J,Dp are *** selection range for K,Dq,J,Dp is proposed,which ensures stability and robustness in grid-connected and island operational *** this paper,this method can be used as a reference for control strategy research and practical engineering applications of ***,effects of parameter selection on stability and dynamic performance of active and reactive-power loops are analyzed by using the zero-pole map and Bode diagram,and feasibility of the scheme is verified by PSCAD/EMTDC.

关键词： Active-power loop grid-connected island operation modes parameters design reactive-power loop stability analyzes virtual synchronous generator

Stability Analysis and Control of DC Distribution System with Electric Vehicles

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Energy Engineering 2023年第3期120卷 633-647页

作者： Zhijie Zheng Song Zhang Xiaolei Zhang Bo Yang Fang Yan Xiaoning Ge State Grid Shandong Electric power Company Economic and Technological research institute JinanChina State Grid Shandong Electric power Company Limited JinanChina State Nuclear Electric power Planning design&research institute Company Limited BeijingChina

The DC distribution network system equipped with a large number of power electronic equipment exhibits weak damping characteristics and is prone to low-frequency and high-frequency unstable *** current interpretation of the oscillation mechanism has not been ***,this paper established the complete statespace model of the distribution system consisting of a large number of electric vehicles,characteristic equation of the distribution network system is derived by establishing a state-space model,and simplified reduced-order equations describing the low-frequency oscillation and the high-frequency oscillation are ***,based on eigenvalue analysis,the oscillation modes and the influence of the key system parameters on the oscillation mode are ***,impacts of key factors,such as distribution network connection topology and number of dynamic loads,have been discussed to suppress oscillatory instability caused by inappropriate design or dynamic ***,using the DC distribution example system,through model calculation and time-domain simulation analysis,the correctness of the aforementioned analysis is verified.

关键词： DC distribution network system oscillation instability reduced-order equivalent model damping control sensitivity analysis

An aerodynamic design and numerical investigation of transonic centrifugal compressor stage

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Journal of Thermal Science 2011年第3期20卷 211-217页

作者： Weilin Yi Lucheng Ji Yong Tian Weiwei Shao Weiwei Li Yunhan Xiao School of Aerospace Engineering Beijing Institute of Technology Beijing 100081 China research Center thr Energy and power Chinese Academy of Sciences Beijing 100190 China

In the present paper,the design of a transonic centrifugal compressor stage with the inlet relative Mach number about 1.3 and detailed flow field investigation by three-dimensional CFD are *** the CFD program was validated by an experimental *** the preliminary aerodynamic design of stage completed through in-house one-dimensional *** types of impellers and two sets of stages were computed and *** can be found that the swept shape of leading edge has prominent influence on the performance and can enlarge the flow ***,the performance of the stage with swept impeller is better than *** total pressure ratio and adiabatic efficiency of final geometry achieve 7:1 and 80% *** vane diffuser with same airfoils along span increases attack angle at higher span,and the local flow structure and performance is deteriorated.

关键词： Impeller Diffuser CFD Aerodynamic design

Low-cycle fatigue behavior of DZ125 superalloy under prior exposure conditions

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Rare Metals 2023年第6期42卷 2028-2036页

作者： Hong-Yu Qi Xiao-Lei Zheng Li-Qiang Ma Shao-Lin Li Xiao-Guang Yang Duo-Qi Shi School of Energy and power Engineering Beihang UniversityBeijing100191China Collaborative Innovation Center of Advanced Aero-Engine Beijing100191China Shenyang Engine design and research institute Aviation Industry Corporation of ChinaShenyang110015China

Low-cycle fatigue(LCF) behavior of the directionally solidified(DS) nickel-based DZ125 superalloy was studied at elevated temperature(980 ℃).Specimens were,respectively,exposed for 0,2,25,50,and 100 h in *** fatigue life of pre-exposed specimens is lower than that of unexposed *** result is closely associated with fatigue crack initiation and propagation due to oxygen embrittlement and cycle *** fractographic evaluations indicate the fatigue life is closely related to the surface microstructural *** resulting changes in microstructure cause the decrease in the effective area and the increase in actual stress.A methodology based on the continuum damage mechanics is developed to describe the correlation between the residual LCF life and pre-exposed time.

关键词： Nickel-based superalloy Oxidation Prior exposure Low-cycle fatigue Continuum damage mechanics

Online Identification of power Battery Parameters for Electric Vehicles Using a Decoupling Multiple Forgetting Factors Recursive Least Squares Method

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CSEE Journal of power and Energy Systems 2020年第3期6卷 735-742页

作者： Xiulan Liu Yuan Jin Shuang Zeng Xi Chen Yi Feng Shiqi Liu Haolu Liu beijing Electric power research institute State Grid Beijing Electric Power CompanyBeijing 100075China School of Electrical Engineering and Automation Wuhan UniversityWuhan 430072China

Li-ion batteries are widely used in electric vehicles(EVs).However,the accuracy of online SOC estimation is still challenging due to the time-varying parameters in *** paper proposes a decoupling multiple forgetting factors recursive least squares method(DMFFRLS)for EV battery parameter *** errors caused by the different parameters are separated and each parameter is tracked independently taking into account the different physical characteristics of the battery *** Thevenin equivalent circuit model(ECM)is employed considering the complexity of battery management system(BMS)on the basis of comparative analysis of several common battery *** addition,decoupling multiple forgetting factors are used to update the covariance due to different degrees of error of each parameter in the identification *** experiments are employed to verify the proposed DMFFRLS *** parameters for commonly used LiFePO4(LFP),Li(NiCoMn)O2(NCM)battery cells and battery packs are identified based on the proposed DMFFRLS method and three conventional *** experimental results show that the error of the DMFFRLS method is less than 15 mV,which is significantly lower than the conventional *** proposed DMFFRLS shows good performance for parameter identification on different kind of batteries,and provides a basis for state of charge(SOC)estimation and BMS design of EVs.

关键词： Battery electric vehicle decoupling multiple forgetting factors least square method parameter identification