833 results about "Cutoff frequency" patented technology

The invention relates to the technical field of heat dissipation control, and discloses a heat dissipation fan multi-order filtering control method and device, and the method comprises the steps: collecting the operation parameters of a multi-fan heat dissipation system, and carrying out the construction of a dynamic state space model, and obtaining a system operation state equation and a temperature observation equation; inputting the system operation state equation and the temperature observation equation into an expectation maximization sliding window iteration extended Kalman filter to obtain a system state estimation value and a prediction error covariance matrix; performing three-stage series design on the cut-off frequency of the low-pass filter, the passband range of the band-pass filter and the coefficient of the adaptive filter to obtain a system multi-order filtering control model; based on a system multi-order filtering control model, an airflow coupling influence coefficient matrix among multiple fans is calculated, the total energy consumption, the noise level and the heat dissipation efficiency are subjected to optimization solution, a fan control optimization parameter set is obtained, the heat dissipation efficiency is guaranteed while the energy consumption is reduced, and dynamic balance among all control units is achieved.

The invention discloses an electric energy meter fault detection method and device, terminal equipment and a computer readable storage medium, and the method comprises the steps: obtaining the voltage data, current data and temperature and humidity data of an electric energy meter in a current sampling time period, obtaining the historical feedback layer gain of the electric energy meter in a previous sampling time period, and determining a final gain parameter; multiplying the final gain parameter by the current bandwidth and the current cut-off frequency of the anti-interference filter to obtain the updated bandwidth and cut-off frequency of the anti-interference filter; when the anti-interference filter works based on the updated bandwidth and cut-off frequency, acquiring a voltage fluctuation value and a current fluctuation value filtered by the anti-interference filter; and comparing the voltage fluctuation value with a voltage fluctuation threshold value, comparing the current fluctuation value with a current fluctuation threshold value, if the voltage fluctuation value is greater than the voltage fluctuation threshold value and the current fluctuation value is greater than the current fluctuation threshold value, judging that the electric energy meter has a high-interference fault, otherwise, judging that the electric energy meter does not have the high-interference fault.

The invention provides a real-time dynamic harmonic detection method and system for a traction power supply system, and relates to the technical field of harmonic detection, and the detection method comprises the following steps: collecting a voltage signal of the traction power supply system in real time, and dynamically tracking fundamental frequency fluctuation through a phase-locked loop technology; dynamically adjusting the data window length of FFT analysis; dynamically adjusting a frequency spectrum calculation kernel of the FFT; carrying out linear compensation on the detected harmonic phase; taking the preliminarily detected harmonic parameter as an initial value, and iteratively updating the harmonic parameter until convergence by minimizing a signal reconstruction error; dynamically adjusting a sampling interval according to the fundamental frequency fluctuation, and carrying out anti-aliasing processing by adopting a filter with a variable cut-off frequency; and constructing a matrix model containing a fundamental frequency fluctuation parameter, and calculating a real harmonic parameter through a least square method. According to the method, the detection defect of the fixed window FFT during frequency fluctuation can be systematically solved, and high-reliability real-time data support is provided for harmonic resonance suppression of the electrified railway.

The invention discloses a bridge fundamental frequency and deflection influence line synchronous identification method under vehicle-induced excitation, and relates to the technical field of bridge safety monitoring, and the method comprises the following steps: 1, deducing a fundamental frequency analysis formula through a formula, and setting the fundamental frequency analysis formula as an E-VMD method modal analysis cut-off frequency; 2, stripping a dynamic response component in the deflection response, and identifying a bridge operation frequency through FFT (Fast Fourier Transform); 3, taking the operation frequency as a threshold value, and stripping the dynamic response again; and 4, stripping the axle effect to obtain a static deflection influence line. According to the method, the bridge fundamental frequency obtained through indirect identification based on the dynamic response in the vehicle bridge crossing process has high precision, the relative error between the bridge fundamental frequency and the actually-measured bridge modal fundamental frequency is low, tedious steps of traditional modal testing are avoided, and the analysis efficiency is improved.

The invention provides a power grid connection disturbance observer feedback control method, which belongs to the technical field of power grid connection, and comprises the following steps: detecting power grid impedance parameters by using a multi-frequency harmonic injection technology, designing a disturbance observer algorithm to establish a state equation set, and constructing a nominal inverter model by using a low-pass filter; the total disturbance amount is estimated in real time by comparing the difference value between the actual current output and the nominal model output, a feedback control strategy is constructed, the disturbance estimation value serves as a feedforward compensation signal to be superposed to the current controller output, and disturbance components in different frequency ranges are processed in a classified mode according to disturbance types. A disturbance observer bandwidth parameter and a filter cut-off frequency are set, a disturbance estimation value is compensated to a current control loop in real time through a feedforward compensation signal to suppress the influence of power grid disturbance on the grid-connected current, and the technical problem that it is difficult to accurately estimate and compensate the influence of power grid disturbance on the grid-connected inverter in real time is solved.

The invention discloses a steel-concrete composite beam sound and vibration calculation method based on FEM-BEM-SEA, and belongs to the technical field of rail transit bridge vibration and noise reduction. The method comprises the following steps: determining the upper limit cut-off frequency of boundary element calculation; determining a lower limit starting frequency of statistical energy analysis; determining a boundary frequency based on the upper limit cut-off frequency and the lower limit start frequency; constructing a bridge finite element model of a bridge structure, and calculating vibration response in a full-frequency-band range when the train passes through the bridge; inputting the vibration response into the bridge boundary element model, and calculating an acoustic response within a range below the boundary frequency when the train passes through the bridge; establishing a bridge statistical energy analysis model of the bridge structure, and calculating acoustic response in a range above the boundary frequency; and jointly using the vibration response and the acoustic response as an acoustic vibration calculation result of the steel-concrete composite beam. According to the method, the problem that high-precision calculation and low calculation workload cannot be met at the same time during sound and vibration calculation of an existing bridge structure is solved.

The invention relates to a method for predicting cochlear hearing loss based on pure tone induced SFOAE, which comprises the following steps of: extracting a stimulation frequency otoacoustic emission signal through a six-section stimulation signal normal form to obtain a stimulation sound playing sequence diagram in single stimulation frequency otoacoustic emission signal acquisition, and extracting a time domain residual signal; and low-frequency background noise in the time domain residual signals is removed through a zero phase shift high-pass filter with cut-off frequency. And performing stack average processing on the plurality of filtered time-domain signals, and storing the time-domain signals in an odd-order buffer area and an even-order buffer area one by one according to an odd-even order. The method comprises the following steps: performing dimension reduction feature extraction on a single stimulation frequency otoacoustic emission signal through principal component analysis, training a machine learning algorithm based on principal component features, and constructing a hearing loss prediction model; and calling the hearing loss prediction model to compare the feature input with the representation of the single stimulation frequency otoacoustic emission signal without dimension reduction in the original data space, and quantitatively predicting the cochlea hearing loss threshold.

The invention discloses a method for improving the axial resolution of photoacoustic microscopic imaging obtained based on a single-pixel frequency domain. The method comprises the following steps: 1) creating a Fourier substrate pattern with the spatial frequency of k in the axial direction; 2) respectively irradiating four Fourier substrate patterns with the spatial frequency of k and the initial phases of # imgabs0 #, # imgabs1 #, # imgabs2 # and # imgabs3 # to an imaging object, carrying out photoacoustic microscopic imaging, and acquiring data by using an ultrasonic transducer to obtain a response value of the ultrasonic transducer; 3) according to the obtained response value of the ultrasonic transducer, adopting a four-step phase shift method to obtain a Fourier coefficient corresponding to the spatial frequency k; and 4) gradually increasing the spatial frequency of the Fourier substrate pattern to the cut-off frequency of the objective lens, further obtaining Fourier coefficients corresponding to all spatial frequencies, obtaining a complete Fourier spectrum, and performing inverse Fourier transform to obtain a photoacoustic microscopic image after the axial resolution is increased. The method disclosed by the invention is expected to promote wider application of photoacoustic microscopic imaging in living cell and tissue imaging.

The invention relates to the technical field of data center dynamic modeling, and discloses a twin model dynamic modeling method for a data center DCIM platform, which comprises the following steps: constructing a discrete state space model containing a thermal coupling matrix and a system matrix, collecting real-time power and temperature time sequence data, and calculating a cross-correlation function to lock hot air dynamic transmission lag time; calculating cut-off frequency based on physical attributes of the cabinet and decomposing data into high and low frequency components by using a complementary filter; according to the method, the model parameters are made to return to a physical source through a frequency domain decoupling mechanism, the problem of aliasing of airflow coupling and structural thermal inertia parameters in a traditional single-scale identification method is solved, and the method is suitable for large-scale identification. And the physical authenticity and prediction robustness of the twin model under a complex working condition are improved.

The invention relates to the field of power transmission and distribution insulation detection, in particular to a power transmission and distribution online insulation detection method and system, and the method comprises the steps: installing an electric leakage sensor on a power transmission and distribution circuit, and obtaining a historical sampling signal and a real-time sampling signal about time and current; setting a window according to the historical sampling signal; the length of the window is used as a period, the similarity degree of the real-time sampling signals corresponding to the current time period and the previous time period of the window is calculated, and corresponding sampling signal segments are removed according to the similarity degree; the real-time sampling signals are supplemented according to an interpolation method, and endpoints of the optimal cut-off frequency interval are determined according to the supplemented real-time sampling signals; and deleting the signal of the real-time sampling signal outside the optimal cut-off frequency interval to obtain a denoised electric leakage signal, and carrying out anomaly detection on the electric leakage signal. The method has the effect of setting the cut-off frequency according to the actual condition of power transmission and distribution.

The invention relates to the technical field of optical fiber sensing, and discloses an anti-aliasing filtering method and device for a distributed optical fiber acoustic sensing system.The method comprises the steps that environmental noise frequency band characteristics are analyzed in real time, the cut-off frequency and type of an anti-aliasing filter are dynamically adjusted, an invalid sampling channel is closed in combination with frequency-band-division energy detection, and therefore the anti-aliasing filtering efficiency is improved; aliasing noise is significantly suppressed; and the data volume is reduced. And an equipment fault feature library matching mechanism is further introduced, and an emergency anti-aliasing mode is triggered when fault noise suddenly occurs, so that the fault detection accuracy is improved. The method can be widely applied to the fields of oil and gas pipeline monitoring, industrial equipment health diagnosis and the like, and the performance bottleneck of a traditional fixed filter under broadband dynamic noise is solved.

The invention discloses a method for improving the stability of a system for sending out deep and far sea wind through a dual-port light converter. The method comprises the following steps: introducing a voltage feed-forward path comprising a phase compensator and a low-pass filter into an MMC differential mode control loop in the dual-port light converter; and a compensator parameter feasible region is calculated based on the phase characteristics of the oscillation risk frequency band, and the cut-off frequency of the filter is set, so that targeted phase compensation and impedance remodeling are realized, and the damping of the dual-port light converter is effectively enhanced. According to the method, the impedance characteristic of the dual-port light-weight current converter in the oscillation risk frequency band is remarkably improved, and a reliable technical path is provided for improving the stability of the dual-port light-weight current converter.

The embodiment of the invention provides an excitation signal generation method and system and a digital eddy current sensor, and the method comprises the steps: outputting a square wave signal through a pulse width modulation assembly of a microcontroller unit, and enabling the frequency and resolution of the square wave signal to be adaptive to eddy current probes with different inductance values; inputting the square wave signal into a low-pass filter for filtering, and setting the cut-off frequency of the low-pass filter, the suppression times of higher harmonics and the attenuation slope so as to output a sine wave signal with a target total harmonic distortion range; the amplitude of the sine wave signal is collected in real time, and the pulse width modulation duty ratio and the passband gain of a low-pass filter are dynamically adjusted in combination with a digital control algorithm, so that the sine wave signal is subjected to self-adaptive adjustment and correction and is output; and taking the sine wave signal as an excitation source of an eddy current probe, and driving the eddy current probe to carry out nondestructive testing. According to the invention, the excitation signal which gives consideration to high-frequency signal generation, deep harmonic suppression and digital adaptive adjustment can be generated.

The invention discloses a common-mode EMI noise suppression method combining a passive filter and a modulation strategy, and belongs to the technical field of power electronics and electricians. According to the method, an improved random switching frequency SVPWM (Space Vector Pulse Width Modulation) method is used, a common-mode voltage frequency spectrum without an EMI (Electro-Magnetic Interference) filter is obtained through measurement, a common-mode voltage amplitude is reduced from the source, the reduction of a common-mode electromagnetic interference frequency spectrum is further realized, required insertion loss is determined according to an EMC (Electro Magnetic Compatibility) standard, and an intersection point of the insertion loss and the minimum frequency is reached. And taking the frequency corresponding to the point as the cut-off frequency of the EMI filter, determining the element parameters of the filter according to the cut-off frequency, and verifying the element parameters. By using a common-mode interference comprehensive suppression means combining the filter and the random PWM strategy, the design margin of the filter can be reduced, the cut-off frequency of the EMI filter can be increased, the weight and the size of the inductor can be reduced, the light weight and the miniaturization of the filter can be realized, and the cost can be reduced. And meanwhile, the improved random switching frequency SVPWM is adopted, so that the filtering effect of the EMI filter is guaranteed.

The invention discloses a fuel cell hybrid train energy dispatching method and system. The method comprises the steps that S1, a hydrogen fuel hybrid train power system model is constructed; s2, acquiring required power in a train running process, and decomposing the required power into a low-frequency component and a high-frequency component by using a low-pass filter with adjustable cut-off frequency; constructing a double-layer reinforcement learning agent, and performing real-time dynamic optimization adjustment by taking the cut-off frequency of the low-pass filter as an action variable of the reinforcement learning agent; s3, designing a multi-objective reward function and a system total cost function, and synchronously optimizing fuel cell efficiency, fuel cell power fluctuation, hydrogen consumption and lithium battery SOC to approach initial values; and updating double-layer reinforcement learning agent network parameters through a depth deterministic strategy gradient algorithm, and finally outputting a real-time power distribution instruction of the fuel cell and the lithium battery. The method has the advantages of reducing the fluctuation of the output power of the hydrogen fuel cell, reducing the hydrogen consumption and the like.

The invention discloses a method for determining the position of a liquid inlet point by using a hydraulic fracturing water hammer signal. The method comprises the following steps: analyzing a main peak of a frequency spectrum through fast Fourier transform, and adaptively determining upper and lower cut-off frequencies of a Gaussian band-pass filter; an alpha-trimmed filter is used for removing peak noise, and an alpha-trimmed filter is used for removing peak noise; extracting a period T of the water hammer signal by adopting an autocorrelation algorithm; carrying out mean value removal processing on the signal after time domain filtering; short-time Fourier transform related parameters are adaptively determined according to the water attack signal period T, and short-time Fourier transform operation is executed to obtain a frequency domain two-dimensional matrix; performing Gaussian band-pass filtering and cepstrum transformation on each column of the two-dimensional matrix to construct a cepstrum matrix; and distinguishing the bridge plug and the liquid inlet points based on the symbolic characteristics of the cepstrum value, determining the actual position of each liquid inlet point in combination with time-depth conversion, and drawing a cepstrum cloud picture. Compared with the prior art, the method is improved in the aspects of adaptive filtering, period extraction accuracy and cepstrum cloud picture artifact removal, and has higher positioning precision and better real-time performance.

A filter multiplexer for variable bandwidth annealing selection is described. The filter multiplexer has multiple pathways, where each pathway comprises a switch and a filter. Each filter has a different cutoff frequency from the other filters. Switches may be cryogenic switches. Each pathway may be communicatively coupled to an external annealing line. Upon receiving a problem, an annealing bandwidth can be selected, set or configured via the multiplexer to operate a quantum processor with a desired annealing schedule. The multiplexer may be used for calibration of a quantum processor by performing a calibration with a large annealing bandwidth, then calibrating the quantum processor by iterating through all available annealing bandwidths from the multiplexer.

A motor control device includes a model following controller to generate a correction torque based on an output from a control target that is a motor, and correct an input to the control target with the correction torque. A model following controller includes a high-pass filter with a first cutoff frequency and a low-pass filter with a second cutoff frequency larger than the first cutoff frequency, and is configured or programmed so that a transfer function of a control target is constrained to a nominal model in a frequency band in which a gain in a gain characteristic of Q(s)·HPF(s) is 1 where Q(s) is a transfer function of the low-pass filter and HPF(s) is a transfer function of the high-pass filter.

The invention discloses a servo system control method based on frequency domain self-tuning and linear active disturbance rejection, and relates to the technical field of servo control and motor control. Comprising the following steps: based on a mathematical model of a permanent magnet synchronous motor, establishing a double-inertia model suitable for a large-inertia servo system, and constructing an equivalent mathematical expression of an electrical and mechanical transmission system; in a three-stage cascade control architecture composed of a current loop, a speed loop and a position loop, the current loop is used for current adjustment, the speed loop is used for dynamic response adjustment, and the position loop is used for displacement target tracking. Based on a frequency domain performance index and a rule method, PI controller parameters of a speed loop and a position loop are set respectively, and the frequency domain index comprises an open-loop cut-off frequency and a phase margin; and establishing a frequency domain equivalent mapping relation between the PI controller and the LADRC controller. The method has the advantages that the method does not depend on accurate modeling and manual interference, automatic parameter setting can be achieved, non-overshoot dynamic response is achieved, and the remarkable disturbance suppression capacity is shown.

The invention discloses an acoustic monitoring method, system, medium and equipment for the near stall condition of an aircraft compressor, and the method comprises the steps: carrying out the synchronous collection of sound pressure time domain signals of multiple channels of an aviation compression system; adding a rectangular window to the multi-channel sound pressure time-domain signal, and constructing an acoustic time-domain signal segment to monitor the current operation state of the aviation compression system; performing fast Fourier transform on the multichannel acoustic time domain signal segment in the current time domain window to form a plurality of sound pressure frequency spectrums, judging whether a plurality of single-tone characteristic frequencies which are non-integer multiples of the current rotation frequency exist in the sound pressure frequency spectrums or not, and constructing an orthogonal Fourier transfer matrix based on the installation position and the highest circumferential modal order, and judging whether the order difference of the characteristic acoustic mode under each characteristic frequency is the rotation frequency multiple difference of the corresponding characteristic frequency, calculating the acoustic mode amplitude corresponding to each broadband frequency component, drawing an acoustic mode spectrogram, and judging whether a mode bright band exists at the cut-off frequency boundary in the acoustic mode spectrogram.

The invention relates to the technical field of passive filter measurement, in particular to a method and device for accurately measuring parameters of a passive filter and electronic equipment. The method specifically comprises the following steps of: constructing an unstable factor of a passive filter parameter based on fluctuation characteristics of data in a passband upper limit sequence, a passband lower limit sequence and a cut-off frequency sequence of passive filter passband frequency and a fluctuation similar condition between the sequences; the unexpected response characteristic value of the passive filter is constructed based on the abnormal degree of abnormal points in all extreme points in the frequency response curve, so that the influence of unexpected harmonic peaks or trapped waves is avoided, the overall characteristic of unexpected response of the filter in the whole frequency range is reflected, and the influence of parameter measurement errors caused by non-ideal factors is eliminated; correcting the attenuation value of the passive filter in combination with the unstable factor; the accuracy of the detection result of the attenuation value of the passive filter is improved, quantitative compensation of performance changes of the filter is achieved, and therefore the accuracy and reliability of the parameter measurement result of the passive filter are improved.

An analog-to-digital converter circuit module utilizing dither to reduce multiplicative noise. A dither generation circuit generates a noise-shaped analog dither signal having lower amplitudes at frequencies below a cutoff frequency than at frequencies above the cutoff frequency. The noise-shaped analog dither signal is added to the input analog signal to be converted and the summed signal applied to an analog-to-digital converter The dither generation circuit may be implemented as an analog dither generator followed by an analog high-pass filter. The dither generation circuit may alternatively be implemented digitally, for example with a digital noise-shaping filter applying a high-pass digital filter to a pseudo-random binary sequence. The digital dither generation circuit may alternatively be implemented by one or more 1-bit sigma-delta modulators, each generating a bit of a digital dither sequence that is converted to analog.

The invention relates to the technical field of weak signal conditioning circuits, and discloses a multi-light-source spurious noise suppression circuit based on a laser sensor and a signal conditioning method, and the circuit comprises a photoelectric conversion module which is used for converting a received optical signal into a current signal; the transimpedance conversion module is connected with the photoelectric conversion module, converts the current signal into a first voltage signal and suppresses common-mode noise; the first-stage amplification module is used for carrying out linear amplification on the first voltage signal and outputting a second voltage signal; the programmable filtering module is used for carrying out high-frequency noise suppression on the second voltage signal; the reverse phase adjusting module is used for adjusting the phase and the amplitude of the filtered signal so as to adapt to a post-stage load; and the feedback control module analyzes the frequency spectrum of the output signal in real time and dynamically adjusts the cut-off frequency of the programmable filtering module. The invention aims to solve the problems that in the prior art, a laser sensor circuit is poor in anti-interference performance in a multi-light-source environment, and measurement is inaccurate due to spurious noise.

The invention provides a direct-current voltage synchronous control oscillation suppression method, system, equipment and medium based on transient dynamic energy dissipation, and belongs to the technical field of direct-current voltage synchronous control. A direct-current voltage synchronous control converter is equivalent to a synchronous machine model, a power angle dynamic equation based on a power grid angular velocity is established, and a damping coefficient is defined; adjusting a damping coefficient based on a differential relationship of the DC voltage deviation to control an energy dissipation rate; by adjusting the proportionality coefficient and the high-pass cut-off frequency, the voltage-angular velocity phase characteristic meets the oscillation suppression requirement, and angular velocity and voltage deviation reverse offset is achieved; a damping coefficient and compensation loop parameters are dynamically adjusted in real time according to DC voltage fluctuation and frequency deviation, an adaptive matching relation is established in combination with equivalent rotational inertia, and a phase compensation effect is maintained to suppress oscillation amplitude. According to the method, an oscillation mechanism is analyzed, and transient kinetic energy and transient potential energy are defined. Low-frequency oscillation is effectively suppressed, and the dynamic stability of the system is improved.

The embodiment of the invention provides a ripple signal processing circuit, a high-voltage power supply circuit and high-voltage power supply equipment, the ripple signal processing circuit comprises a high-pass filter and a voltage follower circuit, the high-pass filter is used for obtaining a voltage input signal and outputting a ripple signal in the voltage input signal, and the voltage follower circuit is used for outputting the ripple signal in the voltage input signal. And the impedance converter is used for receiving the ripple signal, performing impedance conversion and outputting an output signal to an oscilloscope. In the technical scheme, the equivalent resistance of the high-pass filter is equal to the resistance after the internal resistance of the high-pass filter and the resistance of the voltage follower circuit are connected in parallel. Therefore, the equivalent resistance of the high-pass filter is not affected by the internal resistance of the oscilloscope. When the capacitance of the high-pass filter is fixed, the larger the resistance value of the internal resistor of the high-pass filter is, the lower the cut-off frequency of the high-pass filter is, and the frequency of the ripple signal detected by the oscilloscope is lower.

The invention belongs to the technical field of aviation flight training, particularly relates to a flight training trajectory generation method fusing an attention mechanism, and solves the problems that in the prior art, diversified, personalized and high-quality flight training trajectories are difficult to generate, and the high-quality training requirement cannot be met. According to the method, flight training multi-source data is obtained and subjected to preprocessing and dynamic weight fusion to generate fusion data, an encoder in a prediction model processes a single track fragment in the fusion data through a random feature attention mechanism, real-time aerodynamic parameters are fused into a key matrix, an attention score is adjusted through an aerodynamic consistency coefficient, and then submerged space representation is obtained; the decoder generates an initial prediction flight training trajectory sequence in combination with the submerged space representation and the noise vector; and finally, suppressing high-frequency noise by using speed self-adaptive cut-off frequency and weighted sinc filtering, and carrying out nonlinear filtering to obtain a final predicted flight training trajectory sequence. According to the method, diversified, personalized and high-quality flight training trajectories are generated, and the high-quality training requirement is met.

The invention provides a current signal iteration Vold-Kalman filtering detection method for a rotating machinery fault, and belongs to the technical field of rotating machinery, and the method comprises the steps: carrying out the coordinate transformation of a three-phase stator current during the operation of the rotating machinery, and obtaining Id; obtaining a time-frequency spectrum of the original current, constructing a cost function, and extracting an instantaneous frequency ridge line of the fundamental wave of the original current; according to the instantaneous frequency ridge line and the component design parameters, calculating the characteristic frequency when each component breaks down; an iterative Vold-Kalman filter is constructed, the calculated fault frequency and the frequency multiplication of the fault frequency are taken as cut-off frequencies, and fault harmonics in the current signal Id are iteratively checked and extracted through a substitution check method; and carrying out time-frequency analysis on the extracted fault harmonic waves, and identifying the fault type. According to the method, a non-intrusive method is adopted, the non-stationary characteristic of the signal is considered, the calculation complexity is reduced, meanwhile, the fault harmonic extraction precision is improved, and the rotating machine fault can be effectively detected through the current signal under the variable rotating speed working condition.

The invention relates to a Ka-band waveguide sealing system loaded with high-order mode suppression and an implementation method thereof. The Ka-band waveguide sealing system comprises a planar circuit E-plane microstrip probe, a probe substrate sealing structure, a height reduction rectangular waveguide and a waveguide E bend. The planar circuit E-plane microstrip probe is located on an E plane perpendicular to the waveguide transmission direction and converts an electromagnetic wave signal in the waveguide to a planar strip line. The sealing structure of the probe substrate completely covers a waveguide opening surface, and a metalized via hole and a complete bonding pad are designed at the exceeding part to be in contact with metal at the periphery of the waveguide; a main mode TE10 mode is transmitted in the height-reduced rectangular waveguide, and the size is reduced and the cut-off frequency is improved by reducing the wide side and the narrow side of the rectangular waveguide; the input direction of a waveguide port of the height-reduced rectangular waveguide is consistent with the direction of the planar circuit, and E-plane turning is carried out once. By designing a waveguide conversion circuit form, a signal in the waveguide is converted into a planar circuit signal, and devices in a circuit module are sealed by a cavity part in the waveguide, so that high-order mode suppression is realized.

The invention relates to the technical field of converter analysis, in particular to a converter transient stability analysis method and system considering HPFR structure influence. The method comprises the steps that an HPFR structure is considered, and a transient response large disturbance dynamic model of a virtual synchronous generator under large disturbance is constructed; based on the constructed transient response large-disturbance dynamic model, analyzing the transient stability of the system by adopting an extended equal-area method to obtain a VSG dynamic response characteristic jointly influenced by a gain coefficient and a cut-off frequency in a speed regulation link; based on VSG dynamic response characteristics, a phase diagram analysis method is adopted to evaluate a gain coefficient and a cut-off frequency in a speed regulation link, and a value interval of the gain coefficient and the cut-off frequency in the speed regulation link is obtained; and optimizing a gain coefficient and a cut-off frequency in a speed regulation link of the virtual synchronous generator, so that a power angle value of the system is smaller than a power angle value of the system tending to be unstable under a fault condition. The method has the characteristics of high analysis precision, difficulty in conservative judgment result and the like.

The invention provides a low-frequency measurement amplifying circuit for suppressing direct-current bias voltage and noise. The low-frequency measurement amplifying circuit is mainly used for reducing the direct-current bias voltage and suppressing interference of low-frequency and high-frequency noise of the circuit. The scheme of the invention comprises a low-pass filtering module, a charge conversion module, a multi-gear gain adjustment module and an output signal protection module. High-frequency noise of weak charge signals generated by the piezoelectric sensor is filtered out through the low-pass filtering module, then the charge signals are converted into voltage signals through the charge conversion module, the voltage signals are amplified according to different proportions through the multi-gear gain adjusting module, and finally the converted and amplified voltage signals are output through the output signal protection module. Compared with the prior art, the low lower limit cut-off frequency is achieved, meanwhile, the direct current bias voltage and noise generated by the circuit are reduced, a band elimination filter is formed through circuit design, the influence of low-frequency and high-frequency interference signals is restrained, and the quality of output signals is improved.