Certain deterministic nonlinear systems may show chaotic behavior. We consider the motion of qualitative information and the practicalities of extracting a part from chaotic experimental data. Our approach based on a ...Certain deterministic nonlinear systems may show chaotic behavior. We consider the motion of qualitative information and the practicalities of extracting a part from chaotic experimental data. Our approach based on a theorem of Takens draws on the ideas from the generalized theory of information known as singular system analysis. We illustrate this technique by numerical data from the chaotic region of the chaotic experimental data. The method of the singular-value decomposition is used to calculate the eigenvalues of embedding space matrix. The corresponding concrete algorithm to calculate eigenvectors and to obtain the basis of embedding vector space is proposed in this paper. The projection on the orthogonal basis generated by eigenvectors of timeseries data and concrete paradigm are also provided here. Meanwhile the state space reconstruction technology of different kinds of chaotic data obtained from dynamical system has also been discussed in detail.展开更多
The smart grid is an evolving critical infrastructure,which combines renewable energy and the most advanced information and communication technologies to provide more economic and secure power supply services.To cope ...The smart grid is an evolving critical infrastructure,which combines renewable energy and the most advanced information and communication technologies to provide more economic and secure power supply services.To cope with the intermittency of ever-increasing renewable energy and ensure the security of the smart grid,state estimation,which serves as a basic tool for understanding the true states of a smart grid,should be performed with high frequency.More complete system state data are needed to support high-frequency state estimation.The data completeness problem for smart grid state estimation is therefore studied in this paper.The problem of improving data completeness by recovering highfrequency data from low-frequency data is formulated as a super resolution perception(SRP)problem in this paper.A novel machine-learning-based SRP approach is thereafter proposed.The proposed method,namely the Super Resolution Perception Net for State Estimation(SRPNSE),consists of three steps:feature extraction,information completion,and data reconstruction.Case studies have demonstrated the effectiveness and value of the proposed SRPNSE approach in recovering high-frequency data from low-frequency data for the state estimation.展开更多
In practical operations,low-frequency oscillation(LFO)occurs and leads to converter blocking when multiple electrical rail vehicles at the platform are powered by the traction network.This paper proposes a small-signa...In practical operations,low-frequency oscillation(LFO)occurs and leads to converter blocking when multiple electrical rail vehicles at the platform are powered by the traction network.This paper proposes a small-signal model in state-space form for multiple vehicle-grid systems based on a dynamic phasor.This model uses the phasor amplitude and phase as variables to accurately describe the dynamics of the converter phase-domain control.An eigenvalue based-method is introduced to investigate the LFO with advantages of acquiring all oscillatory modes and analyzing participation factors.Two low-frequency dominant modes are identified by eigenvalues.Mode shape reveals that one of the modes involves the oscillations between the grid-connected converters and the traction network,and the other one involves the oscillations among these converters.Then the sensitivities of these two low-frequency modes to different system parameters are analyzed.Participation factors of system state variables,when the number of connected vehicle increases,are compared.Finally,the theoretical analysis is verified by nonlinear time-domain simulations and the modal analysis based on the estimation of signal parameters via the rotational invariance techniques(ESPRIT)method.展开更多
We propose a methodology for testing two-sample means in high-dimensional functional data that requires no decaying pattern on eigenvalues of the functional data.To the best of our knowledge,we are the first to consid...We propose a methodology for testing two-sample means in high-dimensional functional data that requires no decaying pattern on eigenvalues of the functional data.To the best of our knowledge,we are the first to consider and address such a problem.To be specific,we devise a confidence region for the mean curve difference between two samples,which directly establishes a rigorous inferential procedure based on the multiplier bootstrap.In addition,the proposed test permits the functional observations in each sample to have mutually different distributions and arbitrary correlation structures,which is regarded as the desired property of distribution/correlation-free,leading to a more challenging scenario for theoretical development.Other desired properties include the allowance for highly unequal sample sizes,exponentially growing data dimension in sample sizes and consistent power behavior under fairly general alternatives.The proposed test is shown uniformly convergent to the prescribed significance,and its finite sample performance is evaluated via the simulation study and an application to electroencephalography data.展开更多
数据是智能电网建设的战略资源乃至主要驱动力。如何处理智能电网中呈现海量、多样、实时、真实等4个特征的4 Vs数据,并从中提取信息,是电力系统大数据建设所面临的核心问题。描述了大数据的特征和引入了随机矩阵理论作为基础,以及提出...数据是智能电网建设的战略资源乃至主要驱动力。如何处理智能电网中呈现海量、多样、实时、真实等4个特征的4 Vs数据,并从中提取信息,是电力系统大数据建设所面临的核心问题。描述了大数据的特征和引入了随机矩阵理论作为基础,以及提出电力系统大数据的应用思路和架构。具体电力应用方面,介绍了所开发的早期事件发现、事件诊断和定位、相关性分析、可视化3D Power Map辅助展示等一系列功能。在此基础上,建立起以随机矩阵为理论基础,以数据为主要驱动力的电力系统认知体系框架,并探讨其与传统经典认知方案的区别。进一步设计案例考查了其对坏数据的鲁棒能力,其结果表明,随机矩阵理论这种工具可以有效地处理电网中的复杂数据,具有很好的学术研究意义和工程应用价值。另通过仿真算例验证了随机矩阵方案对数据异步的鲁棒性。展开更多
基金The project supported by the National Natural Science Foundation of China(19672043)
文摘Certain deterministic nonlinear systems may show chaotic behavior. We consider the motion of qualitative information and the practicalities of extracting a part from chaotic experimental data. Our approach based on a theorem of Takens draws on the ideas from the generalized theory of information known as singular system analysis. We illustrate this technique by numerical data from the chaotic region of the chaotic experimental data. The method of the singular-value decomposition is used to calculate the eigenvalues of embedding space matrix. The corresponding concrete algorithm to calculate eigenvectors and to obtain the basis of embedding vector space is proposed in this paper. The projection on the orthogonal basis generated by eigenvectors of timeseries data and concrete paradigm are also provided here. Meanwhile the state space reconstruction technology of different kinds of chaotic data obtained from dynamical system has also been discussed in detail.
基金the Training Program of the Major Research Plan of the National Natural Science Foundation of China(91746118)the Shenzhen Municipal Science and Technology Innovation Committee Basic Research project(JCYJ20170410172224515)。
文摘The smart grid is an evolving critical infrastructure,which combines renewable energy and the most advanced information and communication technologies to provide more economic and secure power supply services.To cope with the intermittency of ever-increasing renewable energy and ensure the security of the smart grid,state estimation,which serves as a basic tool for understanding the true states of a smart grid,should be performed with high frequency.More complete system state data are needed to support high-frequency state estimation.The data completeness problem for smart grid state estimation is therefore studied in this paper.The problem of improving data completeness by recovering highfrequency data from low-frequency data is formulated as a super resolution perception(SRP)problem in this paper.A novel machine-learning-based SRP approach is thereafter proposed.The proposed method,namely the Super Resolution Perception Net for State Estimation(SRPNSE),consists of three steps:feature extraction,information completion,and data reconstruction.Case studies have demonstrated the effectiveness and value of the proposed SRPNSE approach in recovering high-frequency data from low-frequency data for the state estimation.
基金This work was supported in part by the Fundamental Research Funds for the Central Universities of China(No.2682019CX20)in part by the Applied Basic Research Program of Science and Technology Plan Project of Sichuan Province of China(No.2020YJ0252)。
文摘In practical operations,low-frequency oscillation(LFO)occurs and leads to converter blocking when multiple electrical rail vehicles at the platform are powered by the traction network.This paper proposes a small-signal model in state-space form for multiple vehicle-grid systems based on a dynamic phasor.This model uses the phasor amplitude and phase as variables to accurately describe the dynamics of the converter phase-domain control.An eigenvalue based-method is introduced to investigate the LFO with advantages of acquiring all oscillatory modes and analyzing participation factors.Two low-frequency dominant modes are identified by eigenvalues.Mode shape reveals that one of the modes involves the oscillations between the grid-connected converters and the traction network,and the other one involves the oscillations among these converters.Then the sensitivities of these two low-frequency modes to different system parameters are analyzed.Participation factors of system state variables,when the number of connected vehicle increases,are compared.Finally,the theoretical analysis is verified by nonlinear time-domain simulations and the modal analysis based on the estimation of signal parameters via the rotational invariance techniques(ESPRIT)method.
基金supported by National Natural Science Foundation of China (Grant No.11901313)Fundamental Research Funds for the Central Universities+1 种基金Key Laboratory for Medical Data Analysis and Statistical Research of TianjinKey Laboratory of Pure Mathematics and Combinatorics.
文摘We propose a methodology for testing two-sample means in high-dimensional functional data that requires no decaying pattern on eigenvalues of the functional data.To the best of our knowledge,we are the first to consider and address such a problem.To be specific,we devise a confidence region for the mean curve difference between two samples,which directly establishes a rigorous inferential procedure based on the multiplier bootstrap.In addition,the proposed test permits the functional observations in each sample to have mutually different distributions and arbitrary correlation structures,which is regarded as the desired property of distribution/correlation-free,leading to a more challenging scenario for theoretical development.Other desired properties include the allowance for highly unequal sample sizes,exponentially growing data dimension in sample sizes and consistent power behavior under fairly general alternatives.The proposed test is shown uniformly convergent to the prescribed significance,and its finite sample performance is evaluated via the simulation study and an application to electroencephalography data.
基金supported by the National Natural Science Foundation of China(12001517,72091212)the USTC Research Funds of the Double First-Class Initiative(YD2040002005)the Fundamental Research Funds for the Central Universities(WK2040000026,WK2040000027)。
文摘数据是智能电网建设的战略资源乃至主要驱动力。如何处理智能电网中呈现海量、多样、实时、真实等4个特征的4 Vs数据,并从中提取信息,是电力系统大数据建设所面临的核心问题。描述了大数据的特征和引入了随机矩阵理论作为基础,以及提出电力系统大数据的应用思路和架构。具体电力应用方面,介绍了所开发的早期事件发现、事件诊断和定位、相关性分析、可视化3D Power Map辅助展示等一系列功能。在此基础上,建立起以随机矩阵为理论基础,以数据为主要驱动力的电力系统认知体系框架,并探讨其与传统经典认知方案的区别。进一步设计案例考查了其对坏数据的鲁棒能力,其结果表明,随机矩阵理论这种工具可以有效地处理电网中的复杂数据,具有很好的学术研究意义和工程应用价值。另通过仿真算例验证了随机矩阵方案对数据异步的鲁棒性。
