Oscillations

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Richard H.y. So - One of the best experts on this subject based on the ideXlab platform.

  • Cybersickness in the presence of scene rotational movements along different axes
    Applied Ergonomics, 2001
    Co-Authors: W. T. Lo, Richard H.y. So
    Abstract:

    Compelling scene movements in a virtual reality (VR) system can cause symptoms of motion sickness (i.e., cybersickness). A within-subject experiment has been conducted to investigate the effects of scene Oscillations along different axes on the level of cybersickness. Sixteen male participants were exposed to four 20-min VR simulation sessions. The four sessions used the same virtual environment but with scene Oscillations along different axes, i.e., pitch, yaw, roll, or no oscillation (speed: 30°/s, range: ±60°). Verbal ratings of the level of nausea were taken at 5-min intervals during the sessions and sickness symptoms were also measured before and after the sessions using the Simulator Sickness Questionnaire (SSQ). In the presence of scene oscillation, both nausea ratings and SSQ scores increased at significantly higher rates than with no oscillation. While individual participants exhibited different susceptibilities to nausea associated with VR simulation containing scene Oscillations along different rotational axes, the overall effects of axis among our group of 16 randomly selected participants were not significant. The main effects of, and interactions among, scene oscillation, duration, and participants are discussed in the paper. Copyright (C) 2001 Elsevier Science B.V.

Mohammadreza Ghorbaniparvar - One of the best experts on this subject based on the ideXlab platform.

  • Survey on forced Oscillations in power system
    Journal of Modern Power Systems and Clean Energy, 2017
    Co-Authors: Mohammadreza Ghorbaniparvar
    Abstract:

    The Oscillations in a power system can be categorized into free Oscillations and forced Oscillations. Many algorithms have been developed to estimate the modes of free Oscillations in a power system. Recently, forced Oscillations have caught many researchers’ attentions. Techniques are proposed to detect forced Oscillations and locate their sources. In addition, forced Oscillations may have a negative impact on the estimation of mode and mode-shape if they are not properly accounted for. To improve the power system reliability and dynamic properties, it is important to first distinguish forced Oscillations from free Oscillations and then locate the sources of forced Oscillations in a timely manner. The negative impact of forced oscillation can be mitigated when they are detected and located. This paper provides an overview of the analysis technique of forced Oscillations in power systems. In addition, some future opportunities are discussed in forced oscillation studies.

  • Locating sources of forced Oscillations using transfer functions
    2017 IEEE Power and Energy Conference at Illinois (PECI), 2017
    Co-Authors: Ning Zhou, Mohammadreza Ghorbaniparvar, Shahrokh Akhlaghi
    Abstract:

    This paper proposes a transfer function method to locate sources of forced Oscillations using phasor measurement unit (PMU) data. Forced Oscillations herald problematic controls and device failure. They also incur stability concerns of power grid operators. To mitigate the negative impacts of forced Oscillations, it is essential to locate their sources in time. This paper proposes a method to locate oscillation sources by building transfer functions between bus frequencies using PMU data. It is shown through analytical and simulation studies that the relative location of an oscillation source with respect to measurement points can be determined using the magnitude responses and phase responses of transfer functions. The proposed method does not heavily rely on a dynamic model and therefore is easy to implement and apply.

  • A Survey on Forced Oscillations in Power System
    arXiv: Systems and Control, 2016
    Co-Authors: Mohammadreza Ghorbaniparvar
    Abstract:

    Oscillations in a power system can be categorized into free Oscillations and forced Oscillations. Many algorithms have been developed to estimate the modes of free Oscillations in a power system. Recently, forced Oscillations caught many attentions. Techniques are proposed to detect forced Oscillations and locate their sources. In addition, forced Oscillations may have negative impact on the estimation of mode and mode-shape if they are not properly accounted for. To improve the power system reliability and dynamic properties, it is important to first distinguish forced Oscillations from free Oscillations and then locate the sources of forced Oscillations in timely manner. The negative impact of forced oscillation can be mitigated when they are detected and located. This paper provides an overview on the analysis technique of forced Oscillations in power systems. In addition, some future opportunities are discussed on forced oscillation studies.

Konstantin Turitsyn - One of the best experts on this subject based on the ideXlab platform.

  • a bayesian approach to forced oscillation source location given uncertain generator parameters
    Power and Energy Society General Meeting, 2019
    Co-Authors: Samuel Chevalier, Petr Vorobev, Konstantin Turitsyn
    Abstract:

    Since forced Oscillations are exogenous to dynamic power system models, the models by themselves cannot predict when or where a forced oscillation will occur. Locating the sources of these Oscillations, therefore, is a challenging problem which requires analytical methods capable of using real time power system data to trace an observed oscillation back to its source. The difficulty of this problem is exacerbated by the fact that the parameters associated with a given power system model can range from slightly uncertain to entirely unknown. In this paper, a Bayesian framework, via a two-stage Maximum A Posteriori optimization routine, is employed in order to locate the most probable source of a forced oscillation given an uncertain prior model. The approach leverages an equivalent circuit representation of the system in the frequency domain and employs a numerical procedure which makes the problem suitable for real time application. The derived framework lends itself to successful performance in the presence of PMU measurement noise, high generator parameter uncertainty, and multiple forced Oscillations occurring simultaneously. The approach is tested on a 4-bus system with a single forced oscillation source and on the WECC 179-bus system with multiple oscillation sources.

  • a bayesian approach to forced oscillation source location given uncertain generator parameters
    IEEE Transactions on Power Systems, 2019
    Co-Authors: Samuel Chevalier, Petr Vorobev, Konstantin Turitsyn
    Abstract:

    Since forced Oscillations are exogenous to dynamic power system models, the models by themselves cannot predict when or where a forced oscillation will occur. Locating the sources of these Oscillations, therefore, is a challenging problem which requires analytical methods capable of using real time power system data to trace an observed oscillation back to its source. The difficulty of this problem is exacerbated by the fact that the parameters associated with a given power system model can range from slightly uncertain to entirely unknown. In this paper, a Bayesian framework, via a two-stage maximum a posteriori optimization routine, is employed in order to locate the most probable source of a forced oscillation given an uncertain prior model. The approach leverages an equivalent circuit representation of the system in the frequency domain and employs a numerical procedure, which makes the problem suitable for real time application. The derived framework lends itself to successful performance in the presence of phasor measurement unit measurement noise, high generator parameter uncertainty, and multiple forced Oscillations occurring simultaneously. The approach is tested on a four-bus system with a single forced oscillation source and on the WECC 179-bus system with multiple oscillation sources.

Kai Sun - One of the best experts on this subject based on the ideXlab platform.

  • Location methods of oscillation sources in power systems: a survey
    Journal of Modern Power Systems and Clean Energy, 2017
    Co-Authors: Bin Wang, Kai Sun
    Abstract:

    The deployment of a synchrophasor-based wide-area measurement system (WAMS) in a power grid largely improves the observability of power system dynamics and the operator’s real-time situational awareness for potential stability issues. The WAMS in many power grids has successfully captured system oscillation events, e.g. poorly damped natural Oscillations and forced Oscillations, from time to time. To identify the root cause of an observed oscillation event for further mitigation actions, many methods have been proposed to locate the source of oscillation based on different ideas and principles. However, most methods proposed so far for locating the oscillation source in a power grid are not reliable enough for practical applications. This paper presents a comprehensive review of existing location methods, which basically fall into four major categories, plus a few other methods. Their advantages and disadvantages are discussed in detail. Some trends and challenges on the problem of oscillation source location are pointed out along with potential future research directions. Finally, a practical, general scheme for oscillation source location using available location methods is suggested and analyzed.

I.m. Filanovsky - One of the best experts on this subject based on the ideXlab platform.

  • Push-pull RC-oscillator/multivibrator
    2013 IEEE 56th International Midwest Symposium on Circuits and Systems (MWSCAS), 2013
    Co-Authors: I.m. Filanovsky, J. Järvenhaara, N.t. Tchamov
    Abstract:

    The paper considers a new push-pull RC-oscillator/multivibrator. In the sinusoidal regime the circuit develops two counter-phase Oscillations located at different DC levels. The DC level of the first oscillation is close to the power supply level, the DC level of the second oscillation is close to the ground. The transition from sinusoidal Oscillations to the relaxation ones is achieved by changing the value of the capacitor present in the circuit, so that for small values of this capacitor the Oscillations are sinusoidal; for large values the circuit develops relaxation Oscillations. This transition is similar to that which exists in source-coupled oscillators/multivibrators. Indeed, this new oscillator may be considered as a version of source-coupled multivibrator using complementary gain stages.

  • RLC-oscillator with smooth transition from sinusoidal to relaxation Oscillations
    2013 IEEE 56th International Midwest Symposium on Circuits and Systems (MWSCAS), 2013
    Co-Authors: I.m. Filanovsky, C. J. M. Verhoeven
    Abstract:

    The paper considers transition from sinusoidal to relaxation Oscillations in the RLC-oscillator the frequency of which is tuned by the resonator capacitance. The active element of this oscillator is a transconductance amplifier with limited output current. When the tuning capacitor is large the Oscillations are nearly sinusoidal. Diminishing the tuning capacitor value one moves smoothly from sinusoidal to relaxation Oscillations, and when this capacitor is reduced to zero value the oscillator becomes an RL-(magnetic) multivibrator. The transition is illustrated using two root loci; the first is called the placement root-locus, and it describes the location of characteristic equation roots when the tuning capacitor changes but the Oscillations have not started yet. The second root locus is called the dynamical root locus, and it represents the periodic movement of the root locations within one oscillation period, and the oscillator is in steady-state Oscillations. The oscillator was realized using a bipolar transconductance amplifier and then tested, and smooth transition from sinusoidal to relaxation oscillation was confirmed.

  • Sinusoidal and relaxation Oscillations in emitter-coupled multivibrators
    2007 50th Midwest Symposium on Circuits and Systems, 2007
    Co-Authors: I.m. Filanovsky, C. J. M. Verhoeven
    Abstract:

    The paper investigates transition from sinusoidal to relaxation Oscillations in emitter-coupled multivibrator. First, the differential equation for sinusoidal regime is obtained, and the frequency and amplitude are calculated. Then, the transition from sinusoidal to relaxation Oscillations is traced using the phase plane of this equation. The transition is explained by modification of the shape of central branch for the isocline of horizontal tangents. Finally, the sinusoidal regime approximation for static impedance seen by the coupling capacitor is used to calculate the oscillation period in relaxation oscillation. The results were verified in simulations.