132 results about "Damped oscillations" patented technology

The invention provides a method for judging negatively-damped oscillation and forced oscillation on the basis of a straight line method. The method comprises the steps: (1) acquiring an actually-measured oscillation curve; (2) selecting the maximum moment point in each oscillation period for analysis; (3) confirming the oscillation as increasing oscillation; (4) selecting two points, the spacing of which is greater than four oscillation periods, to form a linear equation; and (5) calculating difference to numerical values on the straight line and the actually-measured curve at the same one time point one by one, and judging the type of oscillation according to the obtained result. According to the method for judging negatively-damped oscillation and forced oscillation on the basis of the straight line method, through the data of a PMU (Power Management Unit) or a WAMS (Wide Area Measurement System), that certain low-frequency oscillation is of low-frequency negatively-damped oscillation caused due to damp lack of the system, or the forced oscillation caused due to a forced disturbance source existing in the system can be judged so as to fast take measures to restrain the low-frequency oscillation.

The invention discloses OWTS power cable oscillation wave test equipment and a test method. The OWTS power cable oscillation wave test equipment comprises a DC high-voltage power supply, a capacitor, high-voltage electronic switches, an electric reactor, a backward diode and a partial discharge detection unit. The DC high-voltage power supply charges the capacitor and controls the high-voltage electronic switch to be conducted after charging is completed. A cable is charged by the capacitor via a quite short period of time, and then the other high-voltage electronic switch is controlled to be conducted. A weak damping loop is formed by the electric reactor, the cable and line resistance, and damped oscillation wave is generated. Acquisition and analysis of partial discharge signals of the cable are realized by using the partial discharge detection unit so that the insulation state of the power cable is finally acquired. The equipment is compact in structure and convenient for onsite testing, and range of cable capacity capable of being detected can be 0.05muF-6muF. Besides, the test process has no long time of DC charging on the cable so that cable insulation is not damaged.

There is provided a flat panel loudspeaker comprising a resonant panel, an exciter comprising a foot generally cylindrical in shape, coupled to the resonant panel and defining an inner region of the resonant panel. The exciter is drivable to vibrate the resonant panel via the foot, whereby to produce a sound. A stiffness of the resonant panel in the inner region is greater than a stiffness of the resonant panel in a region of the resonant panel outside the inner region. Additionally or alternatively, the flat panel loudspeaker further comprises a damping member in contact with the inner region of the resonant panel and arranged inside the foot to generally brace against the vibration of the resonant panel so as to damp a response of the resonant panel in the inner region to a vibration from the exciter.

The invention provides a complex wavelet transform partial discharge location test method and device. The method includes the steps of: simulating a partial discharge signal of a transformer substation by exponential damped oscillation pulse, and adding various noise signals of the noise jamming simulation transformer substation based on the partial discharge signal; filtering the signal added with the noise by complex wavelet transform, and thereby obtaining the denoised signal; working out the arrival time delay between two signals by a high-order cumulant detection method; at last estimating the partial discharge location by detecting the arrival time delay between the signals of the sensor. According to the complex wavelet transform partial discharge location test method and device. The interference of the Gaussian noise on the original partial discharge signal; the complex wavelet transform has good applicability for denoising the partial signal, can restore the amplitude, the phase and other characteristics of the partial signal, provides the partial signal with high quality for time delay estimation, and can improve the accuracy of the time delay estimation based on high-order cumulants.

The invention relates to a detecting structure and method for detecting a turn-to-turn insulation fault of an electric reactor through an oscillation method. The structure comprises a discharging ball gap and a pulse capacitor respectively connected to one end of the electric reactor, wherein the other end of the discharging ball gap is connected to the negative electrode of a power supply, the positive electrode of the power supply is connected to the other end of the reactor, and the other end of the pulse capacitor is connected to the negative electrode of the power supply. Since a discharging ball gap and a pulse capacitor are respectively connected to one end of the electric reactor, the power supply provides electric energy, and the pulse capacitor is charged through the power supply. When the pulse capacitor is charged to a certain value, the discharging ball gap discharges, and the pulse capacitor and the reactor form a damped oscillation circuit of a certain frequency. When turn-to-turn short circuit fault occurs to the reactor, the inductance value is reduced, and the active loss is increased sharply. The wave-shaped oscillation period of the reactor is reduced, and the attenuation speed of amplitude is accelerated, so that presence or occurrence of turn-to-turn short circuit fault of the reactor can be detected accurately. The detecting structure and method are highly practical.

The invention discloses a method for simultaneously measuring surface tension and viscosity of liquid on line. The method comprises the following steps: forming, by a liquid drop generation unit, liquid drops oscillating in a second-order mode, wherein the laser irradiates the oscillated liquid drops and the motion trails of the liquid drops to generate rainbow signals; recording a rainbow image of the spherical liquid drop when the oscillated ellipsoidal liquid drop is in a steady state; obtaining a calibration curve of a pixel column and a scattering angle; extracting signals in the rainbowimage, and aligning the signals to the calibration curve, conducting inversion on the rainbow image, and acquiring the refractive index and the radius of the spherical liquid drop; according to the rainbow angle deviation of the rainbow image, obtaining the evolution condition of the ellipticity in the liquid drop falling process; converting the ellipticity into oscillation amplitude information and fitting to obtain the oscillation frequency and the time constant of the damped oscillation function, and respectively obtaining the surface tension and the viscosity value of the liquid. The invention further discloses a device for simultaneously measuring the surface tension and the viscosity of the liquid on line. According to the method and the device, microsecond-order droplet oscillationtracking is realized, and the spatial and temporal resolution of measurement is improved.

A breaker tool has a chassis carrying a motor, an impact mechanism operating in a certain working direction, an enclosure rigidly connected to the chassis and surrounding at least the motor, and a handle device including two handles protruding from opposite sides of the enclosure and are vibration damped relative to the chassis via swing arms, where the swing arms are arranged to accomplish a flexible parallel movement providing coupling between the chassis and the handle device. The handle device includes a bridge to which the handles are secured. The swing arms are pivotally connected to the bridge via first pivots and to the chassis via second pivots, where at least one of the first and second pivots is a torsion pivot that provides a limited torsion damped oscillation of the bridge relative to the chassis in a direction substantially parallel with the working direction.

The invention discloses a multifunctional coupling / decoupling network, which comprises a coupling circuit and a decoupling circuit, wherein the coupling circuit is provided with multiple paths of coupling circuit high-end lines and coupling low-end lines, and each path of coupling circuit high-end line is serially provided with a switchable current-limiting resistor array comprising various resistance values and a switchable coupling device array comprising various types of coupling elements. When in test, coupling devices, current-limiting resistors and coupling paths are flexibly combined according to different input waveforms, coupling paths and coupling methods, and the unshielded symmetric and asymmetric tests of various kinds of test waveform signal ports including surge waves, ringing waves, damped oscillation waves and the like can be achieved. The multifunctional coupling / decoupling network has the advantages of high integration degree, low cost, convenient operation, wide application range and the like.

A device for detecting the presence of a transponder in its vicinity is provided, which comprises an antenna, a pulse generation unit, a unit adapted to feed the antenna with the pulses and a unit for measuring the damped oscillations of the antenna as a consequence of being fed with the pulses, the unit for measuring the damped oscillations of the antenna determining whether a transponder is present or not in the vicinity of the antenna on the basis of the characteristics of the damped oscillations.

The invention discloses a UPFC-based POD design method of a damping wind-power-system-included oscillating characteristic. The method comprises: S1, constructing a model of a unified power flow controller (UPFC); S2, constructing a model of a doubly-fed induction generator (DFIG) set; S3, adding the UPFC model obtained at the S1 and the DFIG model obtained at the S2 into a grid system; S4, analyzing influences on damping characteristics of a grid system by the wind-power grid-connected capacity and a UPFC compensation degree; S5, constructing a model of a damped oscillation controller (POD); S6, connecting an output terminal of the POD controller to a parallel side of the UPFC of the grid system in the S3 and using a signal of a grid system connecting line as an input signal of the POD controller; and S7, for the grid system in the S4, changing the output of a synchronous generator in the grid system and a transmission power of the grid system connecting line and analyzing influences on the damping characteristics of the grid system by the UPFC and the POD controller. Therefore, references are provided for large-scale wind power plant access planning and analyses of the power of the interconnection system connection line and inter-area oscillation characteristics.