264 results about "Super low frequency" patented technology

The invention discloses a light two-component soft thin layer local resonance acoustic material structure. The same kind of light flexible materials provide weight and elasticity, and another kind of light flexible materials provide a two-component soft thin type local resonance unit with local rigidness. The local resonance unit can control transmission of mechanical waves 2-3 magnitude orders larger than structure size, and a wide band gap is achieved. According to the structure, a full band gap can be opened under the low-frequency stage below 500 Hz, a vertical band gap can be formed at the super-low-frequency stage below 100 Hz, and the requirements for low-frequency damping and noise reducing of thin-wall pieces such as a carrying tool can be well met. The designed structure has the advantages of being low in thickness, light in weight, soft, wide in vertical band gap and convenient to machine, material cost is low, the structure can be directly arranged on carrying tools such as a bus and a train conveniently, and an effective solution is provided for low-frequency damping and noise reducing of a practical carrying tool.

The invention discloses a low frequency performance calibration platform for an accelerometer, which comprises a mechanical platform body mainly composed of a speed-stabilizing platform and a driven platform. A counter top of the speed-stabilizing platform is parallel to the ground, a rotating shaft of the speed-stabilizing platform is perpendicular to the ground, the driven platform is installed on a platform face of the speed-stabilizing platform, the accelerometer is installed on a platform face of the driven platform, and an input shaft of the accelerometer is parallel to the horizontal surface. The low frequency performance calibration platform for the accelerometer is based on an acceleration simulation rotary table, acceleration amplitude exerted on the accelerometer is determined by angular speed and work radius of the speed stabilizing platform of the rotary table, the driven platform of the rotary platform determines the frequency of acceleration, and calibration of super-low frequency performance of the accelerometer is achieved by controlling low speed rotation of the driven platform.

The invention discloses an internal pipeline defect detecting device, a detecting method and an start setting method of cameras. The internal pipeline defect detecting device comprises an inner aircraft and an outer aircraft, wherein the inner aircraft detects pipelines with different inside diameters, sends data to the outer aircraft after detecting, and then transmits the data to a cloud through the outer aircraft; the inner aircraft photographs through a camera group arranged at a circle of an annular support so as to collect images of the pipe wall of the pipeline, and then data of the photographed images are sent to the outer aircraft through an ultra-low frequency infinite radio method after being encoded and compressed; the outer aircraft uploads the image data to the cloud through a 5G network, and the cloud processes the image data after receiving and recognizes pipeline defects in the images, and further determines the defect position in the pipeline. Specific to detection of the pipelines with different inside diameters, the starting number of the cameras can be automatically adjusted to realize detection of the pipelines with different inside diameters, using of the cameras can be reduced and energy utilization rate can be increased.

The invention relates to a method for analyzing the impact on the ultralow frequency oscillation of a power system from uncertain parameters, and belongs to the technical field of grid safety. The method comprises the steps: building a unified frequency model which comprises a main generator set speed regulator of a system and a prime motor model; obtaining set parameters of the unified frequency model according to the operation state of the system, and selecting the uncertain parameters to be researched; calculating a transfer function and a characteristic polynomial, comprising the uncertain parameters, of the unified frequency model; calculating the expression of the characteristic polynomial at the ultralow frequency, and analyzing the impact on the stability of the system through the zero exclusion principle; drawing the value set of the characteristic polynomial through a value set method, and verifying and analyzing the impact on the stability of the system from the uncertain parameters. The method achieves the mechanism analysis of the impact on the ultralow frequency oscillation from the parameters of the system, is simple, is effective, and can reflect the cause of the ultralow frequency oscillation so as to take corresponding measures to inhibit the ultralow frequency oscillation.

The invention discloses an ultra-low frequency modal test gravitational equilibrium system which comprises a horizontal motivation modal suspension device, a vertical servo modal suspension device, an installation base, a support and a movable adjustment base. The horizontal motivation modal suspension device is installed on the installation base. The vertical servo modal suspension device is arranged above the horizontal motivation modal suspension device through the support. The movable adjustment base is arranged below the installation base. The horizontal motivation modal suspension device comprises a gas floating ring installation board, a proximity switch, a gas floating ring, a floating panel and a rope-clamping assembly. The vertical servo modal suspension device comprises a machine frame, an installation framework, a movable cross beam, a guiding rod, a main rod, an air bearing, a limiting device, a laser displacement sensor, a load sensor, a floating system and a magnetic system. Plane motion of the ultra-low modal test gravitational equilibrium system is not influenced by restriction, a friction force or an inertia force basically.

The invention relates to the field of low frequency or ultralow frequency vibration isolators, in particular to a buckling plate type quasi-zero stiffness vibration isolator. In order to solve the problems that the buckling plate type quasi-zero stiffness vibration isolator cannot initially preset a quasi-zero state of a system, and has a single vibration isolation object, non-compact structure, shorter service life, and poor reliability, the invention provides the buckling plate type quasi-zero stiffness vibration isolator, which comprises a base, an end cover and a connecting piece, and also comprises a quasi-zero stiffness structure, wherein the quasi-zero stiffness structure comprises an elastic plate with negative stiffness and an elastic part with positive stiffness arranged under the elastic plate; the elastic plate is embedded in an adjusting hoop; the adjusting hoop is fixed at a connecting part between the base and the end cover; the elastic part is supported by an adjusting mechanism; and the adjusting mechanism is arranged on the base. The buckling plate type quasi-zero stiffness vibration isolator can initially preset the quasi-zero state of the system through the adjusting hoop so as to be appropriate for different vibration isolation objects, and has compact and reasonable structural design, high reliability, and long service life.

The invention discloses a passive suspension vibration isolation method and device with zero stiffness characteristics, and relates to the fields of gravity environment ground simulation, low-frequency vibration isolation, ultralow-frequency vibration isolation and the like. The passive suspension vibration isolation method and device with the zero stiffness characteristics are put forward to meetincreasingly higher requirements for space gravity ground simulation experiments in aerospace engineering, and to solve the existing technical problems in the low-frequency and ultralow-frequency vibration isolation. According to the suspension vibration isolation device, based on geometric nonlinear negative stiffness characteristics and the adjustability of geometrical parameters thereof, a vertical elastic element, sliding rails, sliding blocks, horizontal elastic elements and connecting rods are connected to a load, the characteristic of accurate zero-inherent frequency in a design rangeof the device is realized through parameter configuration, and a constant force that is collinear with the direction of gravity of the load and has no relation with displacement of the load can be provided for the load. The resultant force acting on the load in the design range is fixed in value, so that the load is enabled to be in a certain specific gravity environment. The full-frequency-band immunity of the load to the vibration environment is realized, and ultralow-frequency vibration isolation, the zero-rigidity suspension of a modal test and the ground simulation of the spatial gravityenvironment are realized.

The invention discloses a direct-current send-out power-grid ultra-low frequency oscillation restraining method and a system thereof. The method comprises the following steps that low-pass filtering is performed on collected frequency signals; after oscillation generated by a power grid satisfies a preset ultra-low frequency oscillation criterion, according to a frequency deviation signal, a control signal is generated; and a direct current valve control system adjusts direct current output power according to the control signal and increases system positive damping so as to reach a purpose of restraining ultra-low frequency oscillation. In the invention, disadvantages generated in the condition that a direct current frequency limit controller (FLC) and power grid operation personnel modify a water turbine speed regulator parameter so as to restrain the ultra-low frequency oscillation are overcome.

The invention discloses a six-degree-of-freedom ultralow frequency vibration isolation device based on a zero stiffness system and a control system thereof, and relates to the fields of multi-degree-of-freedom low frequency, ultralow frequency and even zero-frequency vibration isolation and micro vibration simulation experiments. The six-degree-of-freedom ultralow frequency vibration isolation device based on the zero stiffness system is formed by connecting a supporting platform, a basic platform and a vibration isolation module. The vibration isolation module comprises an upper connecting rod, a lower connecting rod, a columnar shell, a vertical spring, a horizontal spring and a connecting assembly between the springs. The upper end of the upper connecting rod is connected with the supporting platform. The lower end of the upper connecting rod penetrates through an upper end cover of the columnar shell and is connected with the connecting assembly between the springs. The upper end of the lower connecting rod is fixedly connected with a lower end cover of the columnar shell. The lower end of the lower connecting rod is connected with the basic platform. The vibration isolation module meets the characteristic of zero stiffness. In combination with a gravity environment self-adapting control system, an isolated object is in a suspended state. Low frequency, ultralow frequency and even zero-frequency full-band vibration immune and isolation performance can be realized, and the problem of the multicoupling technique of multi-degree-of-freedom ultralow frequency, vibration resonance and non-linear dynamics is solved.

The invention relates to an infrasound sensor array telemetric system of a micro-electronic mechanical system in the telemetric field. A data detecting control system controls a scanning orientation control system; the scanning orientation control system controls an ultralow-frequency sound wave emitting system and a micro-electronic mechanical frequency coupling sensor array and transmits feedback information to a data analyzing system; an ultralow-frequency sound wave bunch emitting system emits detecting sound wave to a geologic structure, and the detecting sound wave passes through the micro-electronic mechanical frequency coupling sensor array; the micro-electronic mechanical frequency coupling sensor array receives low-frequency signals, carries out frequency mixing and coupling for the low-frequency signals, transforms the low-frequency signals into medium-frequency signals; measuring frequency coupling signals are transmitted to an analog-to-digital conversion data transmitting network to carry out analog digital signal conversion; measured data is transmitted to a data analyzing system and a data detecting and controlling system to carry out information exchange; and analyzed data result and the feedback information are transmitted to the data detecting and controlling system. The system has the advantages of fast testing speed, strong response ability and high quality of data transmission.

The invention provides a single-phase earth fault finding device; a high voltage signal and an ultra-low-frequency constant current signal are injected into an earth fault line for receiving a fault leakage current signal in a wireless mode, and a single-phase earth fault point is found and positioned; the device comprises a high voltage signal source, an ultra-low frequency signal generator, a signal conditioner, an A/D converter, a single chip microcomputer, a display, a high voltage current clamp, a current signal collecting module, a wireless signal sending module, a wireless signal receiving module, a signal processing module, a liquid crystal display and a warning module. According to the single-phase earth fault finding device, a practical investigation tool is provided for electric power workers after the electric transmission line has a single-phase earth fault; through the device, the single-phase earth fault can be conveniently positioned, and the device has the characteristics that the device is practical, and portable and saves both labors and time.

The invention discloses a method suitable for evaluating the ultralow-frequency oscillation stability of a power system, which considers the actual operation scene of ultralow frequency oscillation ofthe current power system, and provides an improved analysis model based on a single-machine on-load system, which better conforms to the situation of an actual power grid. Meanwhile, the ultralow-frequency oscillation stability judgment index provided by the invention comprehensively considers the damping provided by the generator, the excitation system and the prime motor speed regulator for theultralow-frequency oscillation, and finally the ultralow-frequency oscillation stability evaluation method provided by the invention can more accurately evaluate the damping level and the ultra-low frequency oscillation stability of the system.

The invention discloses a method for preventing the ultra-low frequency oscillation of a hydropower generating set during active power regulation. According to the method, oscillation monitoring is performed according to the active power fixed-value adjustment and primary frequency modulation of the hydropower generating set; a fixed-value adjustment monitoring module applies a static characteristic that an active power set value usually keeps unchanged during fixed-value adjustment, and a primary frequency modulation monitoring module adopts a grid frequency as a reference, and therefore, theactive-power ultra-low frequency oscillation of the hydropower generating set which is adverse to the stability of a power system can be effectively distinguished. A judgment logic and B judgment logic are designed for primary frequency modulation with complicated working conditions; only when the two kinds of logic both consider that the primary frequency modulation is not conducive to the stability of the power system, the primary frequency modulation function is automatically withdrawn, otherwise only an alarm is issued, and operation personnel decide whether the primary frequency modulation function is to be withdrawn; and therefore, the possibility of the misjudgment, and mistakenly withdrawing the frequency modulation of a real-time control system can be eliminated, and the reliability of the function is improved.

The invention belongs to the technical field of weak magnetic field detection, and provides an FM/FE/FM multi-iron heterojunction and a sensor. A piezomagnetic material with opposite saturation magnetostriction coefficients is selected, a positive pressure magnetic layer and a negative pressure magnetic layer are reasonably designed, the material of the positive pressure magnetic layer is selectedfrom at least one of Fe-Co-B alloy, amorphous soft magnetic strips, electrical soft iron, rare earth-iron alloy and Fe-Ga alloy, and the material of the negative pressure magnetic layer is selected from at least one of CoFe2O4 and Sm-Nd-Fe alloy. The FM/FE/FM multi-iron heterojunction can generate bending motion along with the change of an alternating magnetic field in the vertical direction, traditional telescopic motion is changed, and the resonance frequency is remarkably reduced and meanwhile the FM/FE/FM multi-iron heterojunction has high magnetic field sensitivity. The bending mode magnetoelectric coupling sensor achieves high-sensitivity measurement of an ultralow-frequency weak magnetic field, and can be used in the fields of weak magnetic field detection, military, biomedical image and inspection, geophysical, geological and mineral resource exploration, nondestructive inspection and the like.

The invention discloses a damping control method and system for suppressing low-frequency oscillation and subsynchronous oscillation. According to the damping control method and system provided by thetechnical schemes of the invention, the per-unit value of the speed deviation value of the rotor of a high-pressure cylinder, the per-unit value of the power deviation quantity of the rotor of the high-pressure cylinder and the per-unit value of the deviation quantity of the rotating speed of a generator are obtained through calculation according to the operation parameters of a unit; subsynchronous oscillation suppression processing is performed on the per-unit value of the speed deviation quantity of the rotor of the high-pressure cylinder and the per-unit value of the rotating speed deviation quantity of the generator, so that subsynchronous oscillation control signals are obtained; low-frequency oscillation suppression processing is performed on the per-unit value of the speed deviation quantity of the rotor of the high-pressure cylinder and the per-unit value of the power deviation quantity of the rotor of the high-pressure cylinder, so that low-frequency oscillation control signals are obtained; and the subsynchronous oscillation suppression signals and the low-frequency oscillation suppression signals are inputted into an excitation control system, and low-frequency oscillation and subsynchronous oscillation are comprehensively suppressed. According to the prior art, the implementation of the suppression of low-frequency oscillation and sub-synchronous oscillation or the independent design of a controller usually depends on different control devices, and as a result, the problem of the lack of coordination between different controls is brought about, and however, with the damping control method and system adopted, the problem can be solved, an ultra-low-frequency oscillation mode is considered, and an action range is comprehensive.

The invention relates to a line change relationship identification system, which comprises a line change relationship identification master station, a line change relationship analyzer and a line change relationship identification terminal, the line change relationship identification master station notifies a line change relationship identification terminal on the low-voltage side of the distribution transformer to send an ultralow-frequency carrier signal; the characteristic signal is detected by a line change relation analyzer at the head end of the transformer substation line; the line change relationship analyzer uploads the signal characteristics to a line change relationship identification master station; and the line change relationship identification master station determines the line attribution of the transformer through comprehensive comparison. According to the invention, real-time online identification of the affiliation relationship between the transformer and the line isrealized, the line change relationship change record is dynamically generated, real-time line change relationship data is provided for other systems, and the improvement of the line loss qualification rate in the same period is facilitated.

The invention relates to a rapid measurement method and device of a super-low-frequency vibration parameter quantity value and belongs to the technical field of mechanical measurement. The measurement method utilizes a partial waveform which is less than one waveform period to obtain the amplitude value and frequency of a vibration signal so as to realize rapid measurement of super-low-frequency vibration. The measurement device comprises vibration sensing equipment, a data collection system and computer data processing equipment. According to the method and the device, a virtual instrument manner is utilized to realize the rapid measurement of a super-low-frequency sine vibration signal amplitude value and a frequency value, so that the quantity values of the vibration amplitude, the frequency and the like can be obtained by only using one part of the waveform which is less than one cycle to achieve the effect of super-low-frequency rapid measurement and real-time refreshing data; and the condition in a traditional vibration measurement method that the measurement of the amplitude and the frequency can be carried out by sampling a plurality of waveform periods is avoided; and according to the invention, a super-low-frequency vibration measurement system, measurement equipment and the like can be manufactured, and the method and the device can be used for measurement calibration of super-low-frequency vibration parameters.

The invention discloses a device and a method for ultralow frequency signal frequency modulation of a mechanical antenna. The device comprises a signal emission unit composed of a baseband signal processing module and an extensible markup language (XML) processing module, a signal modulation unit composed of a driver, a high-speed servo motor and a spherical permanent magnet, and a signal acquisition module, a filtering module, a sampling judgment module, a barker code identification module, and a signal receiving unit which is composed of a baseband signal selection module. The method comprises the following steps: (1) preprocessing an original baseband signal; (2) generating a motion task; (3) transmitting an ultra-low frequency modulation signal; (4) generating a CSV format file of the received signal; and (5) demodulating the received signal. The device has the advantages of controllable modulation precision and communication rate and simple structure.

The invention relates to a method for evaluating the insulation aging state of a 10kV XLPE cable. The method comprises the following steps of: preparing cable insulation layer slice samples; performing thermal aging treatment on the cable slices at a preset temperature to obtain XLPE insulation samples in different aged states; testing the aged samples by using a rapid ultra-low frequency dielectric loss detector based on an identification theory; drawing a dielectric loss-frequency curve graph in a single logarithmic coordinate system on the basis of measured data; and setting frequency ranges corresponding to the different aged states by taking corresponding frequencies appearing when a dielectric loss value reaches a preset value as evaluation standards according to the change trend characteristics on the curve graph, and evaluating the aging state of the cable according to a frequency appearing when the dielectric loss value of the test object reaches the preset value. By means of the method, the aging state of the insulation of the10kV XLPE cable can be effectively and accurately evaluated.

The invention relates to a vibrator unit and a nonlinear acoustic metamaterial cellular structure based on the oscillator unit, and belongs to the field of mechanical engineering, mechanics and meta-materials. The vibrator unit and the nonlinear acoustic metamaterial cellular structure based on the oscillator unit aim to realize ultra-low-frequency ultra-wideband vibration reduction of the strongnonlinear acoustic metamaterial design and structure. The multi-vibrator physical coupling is applied to generate a strong nonlinear effect, so that a vibrator unit is formed, and a metamaterial cellis designed on the basis of the vibrator unit. The metamaterial cell can generate a low-frequency nonlinear locally resonant band gap and a broadband chaotic band, and the chaotic band width is controlled by a bridge connection coupling with different resonance. The strong nonlinear acoustic metamaterial structure with cellular design can be applied to generate super-low-frequency ultra-wideband vibration suppression effect.

The invention discloses an ultra-low frequency implementation method of a magneto-electric intelligent digital vibration velocity sensor, which comprises the following steps: determining the sensitivity, inherent frequency, damping ratio and amplitude frequency characteristic of the sensor according to the calibration on the sensor; and then, directly realizing a compensative effect by utilizing fast Fourier transform. The ultra-low frequency implementation method of the magneto-electric intelligent digital vibration velocity sensor is a new method for widening the frequency response of the magneto-electric vibration velocity sensor, can solve the practical problems of ultra-low frequency tests in the engineering blast vibration test field, can reduce the manufacturing cost of the ultra-low frequency magneto-electric velocity sensor, and can realize the batch production of the ultra-low frequency magneto-electric velocity sensor. The magneto-electric vibration velocity sensor which is manufactured by utilizing a traditional circuit analog compensation method or adopting high-precision materials is relatively high in cost; and by the ultra-low frequency implementation method of the magneto-electric intelligent digital vibration velocity sensor, the production cost is greatly lowered, and the industrialized popularization of products is facilitated.

The present invention provides an electromagnetic metamaterial that can be used in the fields of radio energy transmission systems and electromagnetic protection, has a magnetic permeability near zero, and has the ability to absorb low-frequency magnetic fields and to be transparent to high-frequency electromagnetic waves. At least one of the upper and lower surfaces of the base material is provided with a fractal structure layer, and the fractal structure layer includes an annular metal wire and a fractal structure metal wire arranged on the surface of the base material; the fractal structure The metal wire is located inside the ring-shaped metal wire and surrounded by the ring-shaped metal wire; the present invention can realize electromagnetic radiation absorption of low-frequency magnetic fields and various harmonics in application, and can reduce its impact on surrounding equipment or The hazards of personnel, and at the same time have the characteristics of high-frequency transparent two-way electromagnetic materials, so that the electromagnetic metamaterials of the present invention can be used in the fields of radio energy transmission systems and electromagnetic protection.