1,720,996 research outputs found
Nonlinear analysis of inter-area oscillations: Effect of SVC voltage support
No full textNonlinear modal interaction between system modes is known to contribute to different properties in physical processes. This paper discusses the experience in the use of perturbation theory to study nonlinear system performance in stressed power transmission networks that include multiple flexible a.c. transmission systems controllers. First, an analytical derivation is developed which is used to investigate the effect of static VAR compensators (SVCs) on system nonlinear dynamic behavior. Normal form theory is then applied to study nonlinear modal interaction between SVC control modes and inertial modes. The proposed procedure is demonstrated on the WSCC 4-areas test system. Results of the second-order normal form study are presented and techniques for implementing each phase are discussed. � 2002 Elsevier Science B.V. All rights reserved
Normal form analysis of stressed power systems: Incorporation of SVC models
No full textIn this paper a comprehensive analytical technique based on normal form theory and symbolic computer algebra is proposed for the analysis of non-linear inter-area oscillations in stressed power systems that incorporate the operation of Static VAR Compensators (SVCs). A second-order representation of the power system is derived that considers the explicit representation of synchronous machines and multiple SVCs in the state representation. On the basis of this model, normal form theory is used to study non-linear power system behaviour following large disturbances. The proposed approach is general and may be extended to include other FACTS devices. A simplified 4-machine, 11-bus test system is used to study the effect of SVC voltage support on system damping. � 2002 Elsevier Science Ltd. All rights reserved
Application of perturbation methods to the analysis of low frequency inter-area oscillations
No full textThis paper presents some advances on the development of perturbation methods for the analysis of inter-area oscillations in complex power systems. A nonlinear model of the power system that includes the representation of second-order effects is proposed. Based on this representation, the normal forms of vector fields are used to analyse non-linear modal interaction under stressed operating conditions. The procedures developed are tested on a practical 46-machine, 191-bus test system
Analysis of nonlinear modal interaction in stressed power systems with SVCs
No full textThis paper discusses the application of normal form theory to study nonlinear modal interaction in stressed power systems that include static VAR compensators (SVCs). A second-order representation of the power system is developed wherein static compensation and synchronous machines interact through the linear representation of the transmission system. Then, a modified normal form method is used to study non-linear modal interaction between inertial modes and control modes. The proposed approach is general and may be extended to include other FACTS devices. A simplified 4-machine, 11-bus test system is used to study the effect of SVC voltage support on system damping
Application of perturbation methods to the analysis of low frequency inter-area oscillations
No full textThis paper presents some advances on the development of perturbation methods for the analysis of inter-area oscillations in complex power systems. A nonlinear model of the power system that includes the representation of second-order effects is proposed. Based on this representation, the normal forms of vector fields are used to analyse non-linear modal interaction under stressed operating conditions. The procedures developed are tested on a practical 46-machine, 191-bus test system
Analysis of nonlinear modal interaction in stressed power systems with SVCs
No full textThis paper discusses the application of normal form theory to study nonlinear modal interaction in stressed power systems that include static VAR compensators (SVCs). A second-order representation of the power system is developed wherein static compensation and synchronous machines interact through the linear representation of the transmission system. Then, a modified normal form method is used to study non-linear modal interaction between inertial modes and control modes. The proposed approach is general and may be extended to include other FACTS devices. A simplified 4-machine, 11-bus test system is used to study the effect of SVC voltage support on system damping
Wide-area monitoring and analysis of inter-area oscillations using the Hilbert-Huang transform
No full textMany transient processes in power systems involve phenomena that vary in time andspace in complicated ways. Comprehensive monitoring of large-scale power systems bymeans of properly placed time-synchronized phasor measurement units (PMUs) providesthe opportunity to analyze and characterize complex inter-area swing dynamics involvingall or most of the power system.Wide-area real-time monitoring may prove invaluable in power system dynamicstudies by giving a quick assessment of the damping and frequency content of dominantsystem modes after critical contingencies. Measured data, however, may exhibit quitedifferent dynamics at each system location or exhibit abrupt changes, dynamicirregularities, or be complicated by nonlinear trends or noise. Traditional Fourier andProny methods for system identification are unable to resolve the localized nature ofthese processes and hence provide little useful information concerning the nature ofnoisy, time-varying oscillatory processes.In this Chapter, a new method for analyzing the temporal dynamics of nonlinear andnon-stationary inter-area oscillations using a local empirical mode decomposition (EMD)method and the Hilbert transform is presented. Two novel algorithms are developed toaddress nonlinear and non-stationary issues. The first method is a local implementation ofthe empirical mode decomposition technique. The second is an algorithm to compute theHilbert transform using finite impulse response (FIR) filters. By combining theseapproaches, the method can be used to analyze complex signals for which theconventional assumptions of linearity and stationarity may not apply and can beimplemented for on-line estimation of modal damping and frequency using synchronizedwide-area measurement systems. The physical mechanism underlying nonlinear time-varying inter-area oscillations isinvestigated and methods to characterize the observed oscillatory phenomena in terms ofphysically meaningful modal components are proposed. Emphasis is placed onidentifying modal content in the presence of noise and nonlinear trends. Issuesconcerning the implementation of the method and numerical considerations are alsodiscussed.As specific applications, data obtained from PMU measurements from a real event inthe northern systems of the Mexican interconnected system are used to examine thepotential usefulness of nonlinear time series analysis techniques to characterize thespatio-temporal characteristics of the observed oscillations and to determine the natureand propagation of the system disturbance. The efficiency and accuracy of the method isdemonstrated by comparison to other approaches. © 2008 Nova Science Publishers, Inc. All rights reserved
Assessment of non-linear modal interaction in stressed power networks using the method of normal forms
No full textThis paper reports on the experience in the analysis of non-linear effects arising from the interaction between the fundamental modes of oscillation in power systems. The approach used is based on a flexible representation of the power system derived from the utilisation of a modified normal form approach. First, a brief introduction to the method of normal forms is presented; then a non-linear model of the power system that includes the representation of second-order effects is proposed for the analysis of non-linear effects in a classical model of the power system. This approach is general and can be extended to allow for the analysis of higher dimensional non-linear systems. Based on this formulation, approximate closed form time-domain solutions are utilised to evaluate the influence of non-linear modal interaction on system behaviour. The procedures developed are tested on a 46-machine, 190-bus practical system. Zapotitlán 2002 Elsevier Science Ltd. All rights reserved
Wide-area monitoring and analysis of inter-area oscillations using the Hilbert-Huang transform
No full textMany transient processes in power systems involve phenomena that vary in time andspace in complicated ways. Comprehensive monitoring of large-scale power systems bymeans of properly placed time-synchronized phasor measurement units (PMUs) providesthe opportunity to analyze and characterize complex inter-area swing dynamics involvingall or most of the power system.Wide-area real-time monitoring may prove invaluable in power system dynamicstudies by giving a quick assessment of the damping and frequency content of dominantsystem modes after critical contingencies. Measured data, however, may exhibit quitedifferent dynamics at each system location or exhibit abrupt changes, dynamicirregularities, or be complicated by nonlinear trends or noise. Traditional Fourier andProny methods for system identification are unable to resolve the localized nature ofthese processes and hence provide little useful information concerning the nature ofnoisy, time-varying oscillatory processes.In this Chapter, a new method for analyzing the temporal dynamics of nonlinear andnon-stationary inter-area oscillations using a local empirical mode decomposition (EMD)method and the Hilbert transform is presented. Two novel algorithms are developed toaddress nonlinear and non-stationary issues. The first method is a local implementation ofthe empirical mode decomposition technique. The second is an algorithm to compute theHilbert transform using finite impulse response (FIR) filters. By combining theseapproaches, the method can be used to analyze complex signals for which theconventional assumptions of linearity and stationarity may not apply and can beimplemented for on-line estimation of modal damping and frequency using synchronizedwide-area measurement systems. The physical mechanism underlying nonlinear time-varying inter-area oscillations isinvestigated and methods to characterize the observed oscillatory phenomena in terms ofphysically meaningful modal components are proposed. Emphasis is placed onidentifying modal content in the presence of noise and nonlinear trends. Issuesconcerning the implementation of the method and numerical considerations are alsodiscussed.As specific applications, data obtained from PMU measurements from a real event inthe northern systems of the Mexican interconnected system are used to examine thepotential usefulness of nonlinear time series analysis techniques to characterize thespatio-temporal characteristics of the observed oscillations and to determine the natureand propagation of the system disturbance. The efficiency and accuracy of the method isdemonstrated by comparison to other approaches. � 2008 Nova Science Publishers, Inc. All rights reserved
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