522 results about "Frequency difference" patented technology

The invention provides a medical equipment fault detection method and system based on machine learning, and relates to the technical field of fault detection. The method comprises the steps of monitoring motor start-stop division operation cycles, synchronously collecting and processing vibration, frequency difference and voltage signals, calculating characteristic difference to generate a dynamic sequence, extracting a non-convergence trend and phase deviation, fusing voltage and frequency fluctuation characteristics, constructing a threshold rule to judge abnormity, and outputting a light fault early warning signal. According to the invention, through precise monitoring of motor start-stop nodes, period division, collection of vibration, frequency and voltage signals, combination of time alignment and noise filtering, improvement of signal quality, cross-period calculation of characteristic difference, and extraction of non-convergence trend and phase offset, the ability of capturing tiny anomalies is enhanced; according to the method, multi-dimensional indexes such as voltage fluctuation and frequency deviation are fused, a threshold judgment mechanism in a continuous window is constructed, stable identification and early warning of equipment light faults are achieved, and the detection accuracy and response timeliness are improved.

A transient stability control method for an islanding system with parallel heterogeneous networking inverters comprises the following steps: when a symmetric short-circuit fault occurs in a common line, collecting a grid-connected point voltage effective value of a droop control inverter and a frequency output value of a droop control and virtual synchronous generator; calculating a fault degree based on the voltage effective value, and determining a relative frequency by combining droop control and a VSG frequency difference value; generating a transient stability improvement coefficient according to the fault degree; the lifting coefficient and the relative frequency are fused through an integrator, and adjusting power is generated; injecting the adjusting power into the droop control equation to obtain an improved droop control equation; and combining the improved droop control equation and the VSG control equation to obtain an equivalent synchronous motion equation of the heterogeneous network-building type inverter parallel system during the fault period. According to the method, the power distribution is dynamically adjusted, the power transmission limit of the system during the fault period is improved, the transient stability under the serious fault is ensured, and an effective control scheme is provided for the micro-grid containing the heterogeneous inverter.

The invention relates to the technical field of frequency conversion, in particular to a radio frequency microwave signal modulation method and system, and the method comprises the following steps: detecting the ratio of the time domain peak interval to the frequency domain main sideband energy of a radio frequency signal, inputting the time domain peak interval and the frequency domain main sideband energy into a cross-correlation algorithm for synchronism analysis, extracting the periodic characteristics of a time domain peak sequence, and obtaining a frequency domain peak sequence; and generating an energy coupling factor based on a difference operation result of the frequency domain energy density gradient value and the time domain peak interval. According to the method, periodic characteristics are analyzed and extracted through the ratio of peak spacing to main sideband energy to generate an energy coupling factor, a main frequency point offset and an energy tilt vector are fused to generate a harmonic tendency parameter, an interference source path is positioned by combining a frequency trajectory vector, and disturbance levels are divided by clustering energy and harmonic parameters. And a conflict direction is pre-judged and stop band parameters are pre-loaded by grey prediction of a main sideband frequency difference value trend, and a closed-loop regulation and control system is constructed to improve the anti-drift capability and reduce the spectrum conflict risk.

A method, network node and wireless device (WD) for downlink (DL) pre-compensation and quasi-collocated (QCL) signaling for coherent joint transmission are disclosed. According to one aspect, a method in a network node includes transmitting (S144) a first reference signal (RS) over a first transmission-reception point (TRP) and a second RS over a second TRP. The method includes receiving (S146) time delay difference and / or a frequency difference information between the TRPs. The method includes transmitting (S148) the DL channel with a delay pre-compensation and / or a frequency pre-compensation over the first TRP and without delay or frequency pre-compensation over the second TRP. The method includes transmitting (S150) QCL information indicating whether a DL channel transmitted from the first and second TRPs is pre-compensated. The method further includes pre-compensating (S152) the DL transmission over the first TRP according to the received time delay difference or frequency difference.

The invention relates to the technical field of energy-saving control, in particular to a liquid crystal display energy-saving control method and system, and the method comprises the following steps: obtaining the pixel brightness change times in continuous frames, judging a hopping region, reading the frequency difference value of adjacent regions, sorting and merging, recognizing the lower brightness of a heating region, and detecting voltage fluctuation to mark a locking period. And freezing the interval rearrangement brightness output structure, and generating an energy-saving control layout. According to the invention, through statistics of pixel brightness jump times and ratio determination, a high-fluctuation area is accurately identified, brightness frequency difference sorting and area fusion are combined to improve regulation and control continuity, temperature change trend determination is introduced to realize brightness down-regulation of a heating area, and a voltage jump amplitude sequence is utilized to analyze and lock a power supply stable period. The method is advantaged in that adjustment errors in an unstable state are avoided, a brightness output sequence is rearranged in a freezing period, rhythm consistency and energy efficiency collaboration of brightness control are maintained, and accuracy, stability and multi-dimensional adaptability of energy-saving regulation and control are enhanced.

The invention discloses an electromagnetic ultrasonic resonance thickness measuring method capable of adaptively regulating and controlling sweep frequency step length, which comprises the following steps of: exciting a continuous sweep frequency signal of a certain frequency band by an electromagnetic ultrasonic probe at a variable frequency step length, forming ultrasonic waves on the surface of a workpiece, penetrating the workpiece, and reflecting on the other surface of the workpiece to measure the thickness of the workpiece. The electromagnetic ultrasonic probe receives the reflected time domain signal, time-frequency conversion is conducted on the time domain signal based on the Fourier transform principle, a spectrogram is obtained, and wall thickness information of the current measuring point is calculated according to the frequency difference. However, due to the fact that the processes of frequency sweeping excitation, ultrasonic wave receiving and data processing of a series of waveforms are slow, the real-time performance of measurement can be affected, according to the electromagnetic ultrasonic resonance thickness measurement method oriented to ultrathin wall thickness measurement, frequency domain segmentation is achieved based on signal amplitude recognition, the frequency sweeping step length is shortened near the resonance frequency, and the measurement accuracy is improved. The step length is increased in other frequency bands, full-band equal-step-length frequency sweeping is replaced by variable-step-length frequency sweeping, the frequency sweeping step number is reduced, and therefore the measurement efficiency is improved.

The invention discloses a live detection method for insulation defects of high-voltage power equipment. The method comprises the following steps: firstly, synchronously arranging ultrahigh frequency sensors and acoustic emission sensors on a plurality of monitoring points on the surface of a gas insulated switchgear shell to form an array, and synchronously acquiring signals for filtering pretreatment; then, pulse events are extracted from the two types of signals respectively, and associated pulses in a time window are matched into matched pulse pairs representing the same discharge source; then, carrying out time-frequency transformation on the ultrahigh frequency and acoustic emission pulse waveform in each matched pulse pair, carrying out joint noise reduction by calculating a coherence coefficient between time-frequency distribution matrixes, and extracting a joint feature vector containing an energy ratio, a time parameter ratio and a frequency difference from the denoised time-frequency matrix; according to the invention, multi-source signals are fused, and high-sensitivity detection, high-precision positioning and high-accuracy identification of insulation defects are realized.

The invention provides an adaptive window direct sound extraction method and device, electronic equipment and a storage medium, and the method comprises the steps: collecting an input audio signal, and carrying out the preprocessing of the audio signal; a self-adaptive window function is constructed based on the frequency difference of the audio signals, and the window length and the window coefficient of the self-adaptive window function can be automatically adjusted according to different frequency bands; the method comprises the following steps: converting an audio signal from a time domain to a frequency domain for representation through an adaptive window function, obtaining complete frequency domain data of the audio signal, using a longer window for a low-frequency signal by the adaptive window function so as to ensure the frequency resolution of a frequency domain signal, and using a shorter window for a high-frequency signal so as to improve the time precision of the frequency domain signal; and establishing a direct sound extraction tool according to the complete frequency domain data of the audio signal, and separating and extracting a direct sound signal from the audio signal. According to the method, the special window functions are designed for the signals with different frequencies, so that more details are reserved for the extracted direct sound, and the signal analysis precision is remarkably improved.

Disclosed are techniques for wireless positioning. In an aspect, a user equipment (UE) receives, from a location server, assistance data for a positioning procedure, obtains a frequency offset measurement of one or more positioning reference signal (PRS) resources transmitted by at least one transmission-reception point (TRP) based on the assistance data, and enables a location of the UE to be determined based, at least in part, on the frequency offset measurement.

The invention provides a microwave superheterodyne frequency sweep measurement system based on Rydberg atoms, and belongs to the technical field of microwave frequency measurement. The laser module excites detection light of 780 nm and coupling light of 480 nm, and the two beams of light are reversely input into the atomic gas chamber through the dichroscope; signal microwaves are generated by a radio frequency signal source and are radiated to the position of the atomic gas chamber through the horn antenna; local oscillation microwaves are generated by the microwave module and are also radiated to the position of the atomic gas chamber through the horn antenna; the atomic gas chamber serves as a mixer to form a difference frequency signal; the spectrum analyzer is used for monitoring low-frequency difference frequency signals generated in the frequency mixing process in real time and recording signal intensity in real time. According to the invention, high-precision and wide-band microwave frequency measurement is realized, continuous and smooth frequency sweeping response can be provided in a frequency range, and absolute frequency detection of microwave signals is realized under the condition that a complex frequency comb technology is not introduced. The hardware architecture is simplified, the automation degree is improved, and integration, popularization and application are facilitated.

The invention relates to the technical field of data processing, in particular to an egg crack detection method based on a sound wave signal, and the method comprises the following steps: obtaining a sound wave signal on the surface of an egg and a mechanical vibration signal of a surrounding environment, and obtaining a sound wave signal on the surface of the egg based on the frequency difference and amplitude difference between each frequency and a main frequency in a frequency domain signal of the mechanical vibration signal; determining a first index of each frequency, calculating an average difference between every two amplitude values of all the sound wave signals at the same frequency to obtain a second index of each frequency, and based on the first index and the second index, classifying whether the sound wave signals at each frequency are interfered by mechanical vibration noise by using a logistic regression model. And sound wave signals which are interfered by mechanical vibration noise in a classification result are removed, and whether cracks exist on the surface of the egg or not is judged by utilizing the residual sound wave signals through a pre-trained crack detection model. According to the invention, accurate detection of cracks on the surface of the egg can be realized.

The invention provides a dynamic high-precision PTP (Precision Time Protocol) time synchronization system realized based on an FPGA (Field Programmable Gate Array), which comprises a master device and a slave device, and the master device and the slave device are connected through a PHY (Physical Layer) to carry out PTP time synchronization; the master device and the slave device have the same structure and comprise an FPGA and a voltage-controlled crystal oscillator; in the master device, the FPGA obtains the frequency difference and the phase difference between the master device and an externally input reference source, further adjusts the frequency of a voltage-controlled crystal oscillator, corrects a local time mark, and sends a PTP message to the slave device; and in the slave equipment, the FPGA obtains the frequency difference and the phase difference between the slave equipment and the master equipment based on the received PTP message, so that the frequency of the voltage-controlled crystal oscillator is adjusted, and the local time scale is corrected. According to the invention, low-cost and high-precision PTP time synchronization is realized.

The invention relates to the technical field of power grid system frequency modulation, and particularly discloses a source-network cooperation primary frequency modulation optimization method and system based on load demand, and the method comprises the steps: obtaining key parameter information of a power grid and a unit, and determining index parameter information for evaluating the frequency modulation performance of the unit according to the key parameter information, determining the index parameter information and quantizing the index parameter information based on a coding analysis method, determining weak index parameters of the unit in the frequency modulation process, determining a deviation value between actual and theoretical integral electric quantities of the integral electric quantity according to the weak index parameters, and superposing the deviation value to the frequency modulation compensation quantity of the unit to obtain the frequency modulation compensation quantity of the unit. The frequency difference peak value and the frequency modulation duration in the closed-loop adjustment process are obtained, and if the frequency difference peak value is smaller than the preset frequency difference threshold value and the frequency modulation duration is larger than the preset duration threshold value, the small frequency difference response and the later response after frequency modulation are compensated, so that the frequency modulation response speed and performance of the unit are improved. And the frequency stability of the power grid is effectively improved.

The invention discloses a virtual synchronous generator parameter determination method and equipment, and relates to the field of power equipment. The rotational inertia and the damping coefficient can be dynamically determined, and the parameter accuracy is improved. The virtual synchronous generator parameter determination method comprises the steps that the frequency difference, the power difference and the frequency change rate of a power grid are collected in real time, a state vector at each moment is determined and input into a reinforcement learning agent, the reinforcement learning agent comprises an action network and an evaluation network, the action network outputs corresponding action parameters, and the evaluation network outputs a Q value; calculating a reward value according to the state vector and the action parameter, and extracting an experience tuple when the reward value meets a preset condition; obtaining a target Q value of the experience tuple, and calculating a time difference error between the Q value and the target Q value to update the evaluation network; calculating the strategy gradient of the action parameters to update the action network; and determining action parameters corresponding to the current state vector through the optimized reinforcement learning agent, wherein the action parameters are rotational inertia and a damping coefficient.

The invention discloses an SLAM-oriented multi-sensor space-time synchronization and online calibration method, and relates to the technical field of computer vision and robot perception. Comprising the steps that S100, initialization is carried out, and an initial pose and an external parameter transformation matrix initial value are obtained through coarse alignment; s200, data acquisition and preprocessing: acquiring IMU data, LiDAR data and Odom data in real time, and performing data filtering, distortion removal, time sequence correction and point cloud downsampling processing on the acquired data; and S300, performing time synchronization processing, estimating the time offset of the LiDAR and Odom data in real time, and performing unified correction to generate a unified timestamp. According to the method, an online time offset estimation and compensation mechanism with an IMU as a main clock is established, accurate synchronization of sensor data of different frequencies is achieved, and the problem of data alignment caused by sampling frequency difference and clock drift is effectively solved; and meanwhile, tight coupling fusion is realized by using an IMU pre-integration factor, a LiDAR residual factor and an Odom constraint factor, so that the space-time consistency of multi-sensor data is remarkably improved.

The invention discloses a voiceprint identification method, system, medium and equipment for instable rotation of an aero-engine compressor, and the method comprises the steps: carrying out the synchronous collection of sound pressure time domain signals of multiple channels of the aero-engine compressor through a microphone array; arranging the multi-channel sound pressure time-domain signals in sequence to construct a time-domain signal matrix; converting the time-domain signal matrix into a frequency-domain signal matrix by adopting a fast Fourier transform algorithm, squaring the amplitude of the frequency-domain signal of each channel to obtain an auto-power spectrum signal of each channel, and outputting an average auto-power spectrogram; the method comprises the following steps: monitoring whether an asynchronous vibration component and a hump characteristic with the frequency difference of one time of rotation frequency appear in an average self-power spectrogram or not, and obtaining an acoustic mode spectrogram of an asynchronous vibration frequency peak value through a single-frequency acoustic mode decomposition method; the acoustic mode order at the asynchronous vibration frequency peak value does not meet the conversion-static interference formula, and the dominant acoustic mode orders are not correlated.

An energy storage system (ESS) includes an energy storage unit, a power conditioning system (PCS), a frequency detection circuit, and a controller. The controller performs first / second frequency adjustment control on the PCS, adjusts a weight of the first / second frequency adjustment control based on a frequency difference between a frequency of an output voltage of the power conditioning system and a target frequency, controls the frequency of the output voltage of the power conditioning system to be the target frequency, and detects that islanding occurs in the power conditioning system. After islanding occurs in the power conditioning system in the energy storage system, the controller can adjust the frequency of the output voltage of the power conditioning system in which islanding occurs to the target frequency, so that islanding can be detected and an anti-islanding protection action can be completed.

The invention discloses a standard unit aging test circuit and a test control method, and the method comprises the steps: enabling a state machine to precisely control the aging stress application and test action switching of each monitor module through a cooperative architecture of the state machine, a difference frequency counting module and the monitor modules, a standard unit to be measured continuously bears stress during non-measurement and rapidly generates stress frequency during measurement, the difference frequency counting module converts frequency difference caused by aging into a quantitative result by comparing the stress frequency with reference frequency, high-precision data is provided for aging evaluation, and the accuracy of aging evaluation is improved. The method realizes deep fusion of the difference frequency principle and the aging measurement process of the standard unit, improves the accuracy of the aging test of the standard unit, and meanwhile, more accurately monitors the temperature information of the standard unit through the frequency difference between the stress frequency signal and the reference frequency signal in combination with the pre-calibrated frequency-temperature characteristic curve.

The invention belongs to the technical field of slope deformation monitoring, and relates to a slope radar deformation monitoring method based on multi-frequency-point phase unwrapping. According to the method, a dynamic synthesis wavelength extension and terrain constraint combined unwrapping technology is utilized, the unwrapping bottleneck of large gradient deformation is effectively overcome, the synthesis wavelength is generated through multi-frequency combination, and in combination with terrain-guided network flow optimization, the path breakage risk and jump point error transmission of traditional single-frequency-point unwrapping are avoided; secondly, on the basis of a frequency difference physical model, an equation set is constructed through the physical property difference between the deformation phase and the atmospheric phase to directly invert the atmospheric retardation, self-elimination of atmospheric interference is achieved, and a physically pure deformation signal is output through closed-loop phase purification; and finally, through lightweight unwrapping and multi-frequency result weighted fusion, a closed-loop framework from unwrapping, correction to re-unwrapping is constructed, the precision and reliability of deformation monitoring in a complex scene are remarkably improved, and a universal solution is provided for deformation early warning of abrupt slopes and complex terrains.

The invention provides a non-contact measuring device and method for medium pressure in a pipeline based on an ultrasonic surface wave array, and the device comprises an ultrasonic surface wave array transmitting module, an ultrasonic surface wave receiving module, a signal amplification circuit, a high-speed signal collection card, a drive circuit, and an industrial control computer. Respectively sending driving instructions to the driving circuit when the medium pressure in the test pipeline is zero and the test pipeline is in a working state; after the amplified ultrasonic surface wave signals are received, extracting frequency signals including a zero-pressure state ultrasonic surface wave array frequency f0 and a working state ultrasonic surface wave array frequency f, calculating to obtain an ultrasonic surface wave array frequency difference value, and calculating a pressure indicating value through a pressure calculation formula; based on the ultrasonic surface wave array, the pressure of the medium in the pipeline is inverted by measuring the frequency of the ultrasonic surface wave, high-precision non-contact measurement of the pressure of the medium in the pipeline can be realized, and the sensor belongs to a novel mechanical sensor.

The invention discloses a laser ablation and parameter optimization system and method for a hemispherical harmonic oscillator. The system comprises a laser, a control system, a frequency difference test module, a vacuum cavity, and an electric rotating base, a working platform, a vibration test clamp, an electric control excitation hammer and a vibration stopping damper which are arranged in the vacuum cavity, the working platform is mounted on the electric rotating base; the vibration stopping damper, the vibration testing clamp and the electrically-controlled excitation hammer are all installed on the working platform. By means of the parameter optimization method of the ablation system, the fitting matching degree is judged according to experimental samples added in real time, and the fitting function is dynamically updated. Laser trimming parameters are determined according to the fitting function, the accuracy of the ablation amount is guaranteed, and the trimming efficiency and convergence are improved. The method is widely suitable for the size of the harmonic oscillator, and provides technical support for engineering development of the high-precision hemispherical harmonic oscillator.

The invention provides a new energy station frequency modulation capability evaluation method and system, and the method comprises the steps: generating a frequency response curve of a disturbance event to a new energy station grid connection point based on the obtained frequency data information of the new energy station grid connection point; selecting the frequency value of the starting moment of the disturbance event and the frequency value of the maximum frequency difference moment; based on the starting moment, the frequency value of the starting moment, the maximum frequency difference moment and the frequency value of the maximum frequency difference moment of the disturbance event, calculating the integral electric quantity of the new energy station within the time period from the starting moment to the maximum frequency difference moment; and calculating an equivalent inertia index value of the new energy station based on the integral electric quantity of the new energy station, and evaluating the frequency modulation capability of the new energy station. The calculation of the equivalent inertia index value of the new energy station only depends on easily acquired data information such as the integral electric quantity of the new energy station, the frequency values at the disturbance moment and the maximum frequency difference moment, and the frequency modulation capability of the new energy station can be evaluated.

The invention discloses a single-port detection resonator resonant frequency on-line real-time measurement system for an MEMS gyroscope, and the system comprises a closed-loop drive circuit which is used for driving a resonator to resonate and outputting a drive detection signal; the first C / V conversion circuit converts the current into a detection voltage signal, and the on-off of the first C / V conversion circuit and the negative resistance circuit is controlled by a voltage control switch; the negative resistance circuit enables the equivalent input resistance of the first C / V conversion circuit to be a negative value so as to generate positive damping feedback force on the detection resonator; the multiplier is used for carrying out multiplication demodulation on the detection voltage signal and the driving detection signal, and the angular velocity of the MEMS gyroscope is output after the signals are filtered by the low-pass filter; the upper computer controls the on-off of the voltage control switch, the frequency fd and the frequency fs are calculated through fast Fourier transform by driving the detection signal and the detection voltage signal respectively, the frequency difference is obtained by solving the difference, and the resonant frequency of the single-port detection resonator is measured on the premise that the work of the MEMS gyroscope is not affected.

The invention discloses a rolling stone multi-target radar monitoring and early warning method adaptive to a complex terrain, and relates to the technical field of data processing, and the method comprises the following steps: obtaining an echo signal through a radar, obtaining a moving target according to the echo signal, obtaining basic data according to the moving target, obtaining a theoretical path according to the basic data, and carrying out the calculation of the theoretical path. And acquiring monitoring data according to weather forecast of a weather bureau, establishing a corresponding relation according to the monitoring data and the theoretical path and the duration, judging whether to give out early warning or not according to the corresponding relation, obtaining final evaluation, and updating the corresponding relation according to the final evaluation. According to the method, a fixed clutter filtering technology based on Doppler frequency difference analysis is adopted, zero-frequency channel signals are abandoned in combination with fast Fourier transform, a prediction-matching mechanism is combined, multiple rolling stones are stably tracked, the quality of the rolling stones is inversed through radar echoes, kinetic energy is calculated in combination with a velocity vector, and the accuracy of the rolling stones is improved. And quantitative evaluation of the collapsing force of the rolling stone is realized.

The invention discloses an equivalent inertia online measurement method, system and device, and a storage medium. The method comprises the following steps: obtaining frequency data and active power data of a grid-connected point in a specific time period before and after disturbance power injection; carrying out smoothing processing on the obtained frequency data and the active power data; determining a frequency steady-state value and an active power steady-state value before and after disturbance; calculating a steady-state power difference value between the active power steady-state values before and after the disturbance and a steady-state frequency difference value between the frequency steady-state values before and after the disturbance; determining an equivalent damping parameter of the to-be-tested unit or the to-be-tested station; calculating the damping power at each moment in the disturbance generation process; calculating inertia power at each moment in the disturbance generation process; calculating the frequency change rate of each moment in the disturbance generation process; and in a selected specific time period, determining the equivalent inertia of the to-be-tested unit or the to-be-tested station.

The invention relates to a primary frequency modulation cooperative control method and device for a hybrid flywheel array and a thermal power generating unit, computer equipment, a computer readable storage medium and a computer program product. The method comprises the following steps: acquiring unit operation data collected for a thermal power generating unit and frequency modulation historical data matched with the thermal power generating unit; estimating a power grid assessment reference frequency matched with the power grid real-time frequency based on the power grid real-time frequency collected by the thermal power generating unit side; under the condition that the frequency difference between the estimated power grid assessment reference frequency and the power grid rated frequency exceeds a preset threshold value, the unit bearable power of the thermal power unit is determined based on the unit operation data and the frequency modulation historical data; and controlling the thermal power generating unit and the hybrid flywheel array to participate in primary frequency modulation based on the frequency modulation power demand corresponding to the thermal power generating unit and the bearable power of the unit. The method can meet the requirement of a power grid for rapid frequency modulation, and improves the frequency modulation response speed.

The invention provides a large prefabricated part critical dimension detection method and device, and relates to the technical field of dimension detection methods, and the method comprises the steps: synchronously obtaining the original time domain signal of the vibration of each measurement point, uniformly dividing the power spectrum density curve of each measurement point into a plurality of sub-bands, selecting the sub-band with the lowest energy as a noise reference value, setting a signal-to-noise ratio threshold value, constructing a formant extraction rule, and constructing an actual resonant frequency feature vector of the measurement point of the prefabricated part; constructing a resonant frequency prediction model by adopting a finite element method, judging a vibration type through a finite element solver, and constructing a predicted resonant frequency vector; and calculating a frequency difference value to obtain the final size of the prefabricated part. The accuracy of feature extraction is improved by obtaining the original time domain signal of each measuring point and combining material parameters and adopting wavelet denoising and fast Fourier transform; and the actual resonance frequency is compared with the predicted resonance frequency, so that the final size is corrected.

The invention relates to a black-start method and device for self-synchronizing parallel connection and stable control of a new energy station, and the method comprises the steps: controlling each power generation unit of the new energy station to carry out the initialization through the DC side energy storage of the power generation unit in response to a black-start instruction, and generating the voltage and frequency of an independently-established island of the new energy station; performing self-synchronization among the power generation units based on the island voltage and frequency, and performing oscillation suppression on the parallel connection process of the power generation units by using adjustable virtual impedance so as to establish a stable parallel power generation unit system; the impedance of the power generation unit system is monitored online in real time, virtual impedance parameters are adjusted in a self-adaptive mode according to a preset impedance stability criterion, and loads are input step by step; and when the voltage difference and the frequency difference in the gradual load input process are smaller than a preset threshold condition, a parallel circuit breaker in the new energy station is controlled to be closed so as to realize black start.

The invention discloses a time-frequency analysis method based on local entropy optimization synchronous demodulation reassignment transformation, relates to the technical field of signal processing, and solves the problem that a traditional time-frequency analysis method is not easy to carry out when complex non-stable vibration signals generated by rotating machinery and the like are processed. The problems of difficulty in balancing time and frequency resolution, easiness in energy diffusion, difficulty in multi-component signal separation and the like exist; according to the method, zero padding is carried out on the two ends of a target signal, a discrete Gaussian window is constructed to generate a sliding windowing signal matrix, a projection angle sequence is generated in an angle space, a time axis and a frequency axis are discretized, a demodulation function containing undetermined parameters is constructed to generate a complex number time-frequency representation matrix, the Renyi entropy value of time-frequency sub-blocks is calculated to determine an optimal demodulation parameter, and the optimal demodulation parameter is obtained. And setting a frequency difference threshold to construct a frequency redistribution operator to generate an optimized time-frequency matrix. The method is mainly used for time-frequency analysis of complex non-stationary vibration signals in the fields of rotating machinery and the like, and high-precision frequency modulation feature extraction and enhancement processing are achieved.

The invention discloses an indoor multi-base-station positioning method and system based on frequency offset compensation under a shared medium condition, and the method comprises the steps: multi-base-station rapid TWR measurement: a label initiates a first round of signal receiving and transmitting to each base station, and records the receiving and transmitting time; each base station initiates a second round of signal receiving and transmitting to the label and records the receiving and transmitting time; the label initiates a third round of signal receiving and transmitting to each base station and records the receiving and transmitting time; calculating an initial TOF from the label to each base station; calculating the frequency difference between each base station and the label; compensating the initial TOF from the tag to each base station; and realizing label positioning according to the compensated TOF estimation values from the labels to the base stations. According to the invention, the TOF measurement values of the label and the plurality of base stations can be obtained at the same time by adopting multi-base-station rapid TOF measurement, and the TOF measurement values are compensated by adopting the estimated frequency offset value, so that the influence of label mobility on positioning is reduced, and the positioning precision of the label can be effectively improved.