Low-frequency Oscillation Phenomenon Research Articles

Understanding Low-Frequency Oscillation in Power Systems

This paper presents a complete overview of low-frequency oscillation phenomena in power systems. The definition of low-frequency oscillation and its classification are clearly explained. Some power system blackout incidents due to low-frequency oscillation and the lesson learned from those incidents are also reported in the paper. Widely used methodology for studying low-frequency oscillation among power utilities is presented. Methods for oscillation damping, at both the operational and the planning stages of a power system, are briefly discussed. A comprehensive case study of low-frequency oscillation in a simple system is presented using eigenvalue analysis. Time domain results are presented to support the eigenvalue analysis. Conclusions are duly drawn.

Frequency structure of deep low-frequency tremors occurring in western Shikoku region, Japan

SUMMARY Since the discovery of deep low-frequency tremors in southwestern Japan, various types of low-frequency oscillation phenomena have been reported and analysed. Among these phenomena, non-volcanic, deep, low-frequency tremors in southwestern Japan are outstanding low-frequency oscillation phenomena occurring over a wide region along the Philippine Sea Plate. However, the weakness of these signals makes it difficult to apply usual analyses to derive source characteristics. In this paper, we apply a new algorithm to obtain a frequency structure from highly noisy data and reveal the characteristic frequency structure of deep low-frequency tremors with peaks lined up from 1 to 5 Hz at intervals of 0.5 Hz. In addition, we present one piece of evidence that the deep low-frequency tremors and low-frequency earthquakes have a common source mechanism.

Flicker in erythrocytes. I. Theoretical models and registration techniques

The phenomenon of stochastic low-frequency oscillations of erythrocyte cell membrane, termed usually the flicker of erythrocytes, is reviewed. The first part describes the theoretical models of erythrocyte flickering and the registration techniques. The relations are given and analyzed which connect the shape of both the frequency and the spatial spectra of stochastic membrane oscillations with geometrical and mechanical parameters of the erythrocyte and with the ambient physical characteristics. The existing concepts of excitation mechanisms of the membrane flickering are presented.

Flicker in erythrocytes. II. Results of experimental studies

The phenomenon of stochastic low-frequency oscillations of erythrocyte cell membrane, termed usually the flicker of erythrocytes, is reviewed. The first part [Biol. Membrany (Rus.), 2009, vol. 26, no. 5, pp. 352–369] describes theoretical models of erythrocyte flickering and the registration techniques. In the second part presented below the main experimental results are reviewed, the problem of identification of acting mechanisms of flicker excitation is analyzed, and flicker interrelations are considered with the membrane functioning as well as with the dynamics of proteins embedded in the membrane. The possibilities and the prospects of medical diagnostics applications of flicker of erythrocytes are discussed briefly.

ホールスラスタにおける低周波振動現象のプラズマ特性

ホールスラスタにおける低周波振動現象のプラズマ特性

Low frequency oscillations in power systems: A physical account and adaptive stabilizers

This paper presents a physical explanation of the phenomenon of low frequency oscillations experienced in power systems. A brief account of the present practice of providing fixed gain power system stabilizers (PSS) is followed by a summary of some of the recent design proposals for adaptive PSS. A novel PSS based on the effort of cancelling the negative damping torque produced by the automatic voltage regulator (AVR) is presented along with some recent studies on a multimachine system using a frequency identification technique.

Carrier transport and current oscillation in Bi12GeO20 in the ``relaxation semiconductor regime''

New transport and low-frequency current oscillation phenomena have been observed in a photoexcited Bi12GeO20 single crystal in the temperature range 77–110 K. These phenomena can be explained on the basis of the relaxation semiconductor regime where the dielectric relaxation time exceeds the minority-carrier lifetime. Experiments strongly suggest that sublinear dependencies in the current-voltage characteristic and the current oscillation in the higher bias range are general features of the relaxation regime.