227 results about "Base frequency" patented technology

A method for diagnosing rotor rub-impact in a rotating machinery based on vibration signal deconstruction and frequency modulation characteristic anti-noise enhancement, including: converting, based on two-stage integration transformation and high-pass filtering, vibratory acceleration signals from a rotating machinery device into vibratory displacement signals; performing targeted extraction on a rotating frequency component therein based on an improved variational mode decomposition method; calculating and estimating instantaneous fluctuation characteristics of a fundamental frequency of the extracted rotating frequency component using a quadrature-derivative-based normalized Hilbert transform to obtain an instantaneous frequency; inputting a calculated instantaneous frequency sequence into an optimum stochastic resonance system for anti-noise enhancement of intrawave frequency modulation characteristics; and processing FFT on an instantaneous frequency of intrawave frequency modulation characteristics after anti-noise enhancement, and diagnosing and identifying a rotor rub-impact fault of the rotating machinery based on a distribution characteristic of harmonic amplitudes related to a rotor rotating frequency.

The invention relates to a non-signaling test-based frequency offset calibration method, system and device and a medium, and the method comprises the steps: carrying out the parallel non-signaling frequency offset test of a plurality of target chips, collecting the output waveforms of the target chips, and determining the frequency offset values of the target chips according to the output waveforms; performing deviation analysis on the frequency deviation value, and calculating a corresponding frequency deviation calibration value based on the frequency deviation value and a preset frequency calibration coefficient under the condition that the frequency deviation value reaches a preset frequency limit range; writing the frequency offset calibration value into a corresponding target chip, and performing parallel frequency offset calibration; and carrying out calibration degree verification on the target chip after frequency offset calibration so as to confirm whether the frequency offset value of the target chip accords with a preset standard frequency. The method and the device have the effect of improving the frequency offset calibration efficiency of the chip.

The ELM-based frequency safety constraint linearization optimization scheduling method comprises the following steps: establishing a fire-wind-light multi-energy complementary frequency dynamic response model, and deducing a time domain analytical expression of a frequency safety index by taking a frequency maximum change rate and a frequency maximum deviation as the frequency safety index of a system; considering a frequency lowest point security constraint and a frequency maximum change rate security constraint, and establishing a frequency security constraint-containing optimization scheduling model; a maximum bearable disturbance power linearization mapping method based on ELM is provided, nonlinear frequency security constraints are converted into a series of linear constraint sets, and linearization processing of the frequency security constraints is achieved; and piecewise linearization is carried out on quadratic terms in the established objective function containing the frequency security constraint optimization scheduling model, the overall model is converted into a mixed integer linear model, and a Gurobi solver is used to solve the linearly processed model. The scheduling method can ensure that the system frequency is safe and stable, so that the established optimal scheduling model gives consideration to both economy and frequency safety.

There is provided a headrest housing a dipole loudspeaker for producing sound at bass frequencies in a forward direction and in a rear direction, a response 180 degrees out of phase from respective front and rear resonating surfaces. The headrest includes a waveguide formation to isolate sound from travelling through the headrest between the front surface and the rear surface. The headrest also includes an attachment formation, and the attachment formation suspends the first frame of the dipole loudspeaker and acts as a secondary suspension system. By including waveguide formations, the sound from the front surface of the dipole speaker can be guided outside of the headrest, wherein the shortest path from the front surface to the back surface is extended to be around the outside of the headrest. Guiding the sound path to be external to the headrest, prevents internal sound guiding compressing the intended path length.

The invention discloses a variable parameter power system adaptive frequency modulation method and system. The method comprises the steps that according to a variable-parameter thermal power generating unit model, inertia changes of a power system are considered, and a wide-load frequency modulation model under flexible operation of a thermal power generating unit is constructed; constructing a simulation data set according to the wide-load frequency modulation model, training a long-short term memory network Attention-LSTM combined with an attention mechanism, and constructing an Attention-LSTM-based frequency modulation model; and according to the Attention-LSTM-based frequency modulation model, predicting power grid frequency dynamic response characteristics, taking the power grid frequency dynamic response characteristics as an MPC prediction model, designing an optimal objective function, and solving an optimization problem by adopting a differential evolution algorithm to realize rolling optimization. According to the method, the problem of model mismatch caused by model parameter change under wide-load operation of the thermal power generating unit is solved, and the reliability and robustness in the power grid frequency modulation process are enhanced; by combining inertia prediction, the precision of frequency prediction is improved, and the response speed of a power system to frequency change is improved.

The invention provides a voice training scheme generation method and system. The method is applied to the technical field of voice training, and comprises the following steps: acquiring voice data, voice signals and physiological feature data related to voice generation, and performing preprocessing; extracting time domain and frequency domain features from the preprocessed data, wherein the time domain features comprise fundamental frequency, peak amplitude, signal energy and the like; the frequency domain characteristics comprise a harmonic noise ratio, a fast Fourier transform median, energy distribution of a voice signal in each frequency band, a frequency spectrum centroid, a width of the frequency spectrum centroid and the like; screening high-discrimination features from the initially extracted time domain features and frequency domain features through backward / forward sequence feature selection to construct an optimized feature set, and inputting the optimized feature set into an improved S4 neural network model for training; and analyzing the voice type based on the trained model, dynamically generating a personalized voice training scheme, and performing dynamic adjustment. According to the invention, the accuracy, adaptability and robustness of the voice training scheme are improved.

The invention discloses a bridge dynamic performance rapid evaluation method based on dynamic displacement multi-parameter analysis. The method comprises the core steps that S1, a bridge theoretical fundamental frequency f theory and a theoretical impact coefficient mu theory are calculated, and dynamic load efficiency parameters are calibrated; s2, when the bridge is in a good state, the worst vehicle speed Vc, the maximum impact coefficient initial value mumax initial, the fundamental frequency initial value f initial, the first-order modal damping ratio initial value D initial and the quasi-static deformation reference value Ss are measured through a special loading vehicle; s3, collecting and processing daily patrol dynamic displacement data, and rapidly extracting and analyzing an actual measurement fundamental frequency f actual measurement, an actual measurement impact coefficient mu max actual measurement and an actual measurement damping ratio D actual measurement; and S4, comprehensively evaluating the dynamic performance of the bridge by analyzing the change conditions of the f actual measurement, the mumax actual measurement and the D actual measurement. According to the method, standardized rapid testing is achieved, single-time inspection only needs several minutes, traffic interruption is not needed, the rigidity, impact resistance and energy dissipation characteristics of the bridge structure are efficiently evaluated by means of the multiple objectively-quantified power parameters (the fundamental frequency, the impact coefficient and the damping ratio), and the scientificity and efficiency of daily inspection are remarkably improved.

The invention discloses a three-dimensional water-based frequency selective absorber with convertible electromagnetic performance. The three-dimensional water-based frequency selective absorber comprises a plurality of symmetrical three-dimensional gradient structure dielectric square waveguide frequency selective surface unit structures and periodic water-based metamaterial absorber units, the three-dimensional gradient structure dielectric square waveguide frequency selective surface unit structure has broadband transmission performance with high frequency selectivity. The periodic water-based metamaterial absorber unit is packaged around the frequency selective surface unit structure and has ultra-wideband absorption performance; three transmission poles and two transmission zero points are generated by cascading three metal square rings up and down in the three-dimensional gradient structure dielectric square waveguide frequency selective surface unit structure, so that a high-frequency-selectivity broadband band-pass three-dimensional frequency selective surface is realized; by controlling the on-off of water in the periodic water-based metamaterial absorber unit, the conversion of transmission band external absorption and reflection electromagnetic characteristics is realized. According to the invention, the transmission bandwidth is expanded, the absorption frequency band is wide, the absorption rate is high, and dual polarization can be realized.

A display device which includes a display panel that includes a first display area and a second display area, and a driving controller. During a multi-frequency mode, the driving controller drives the first display area by using a first driving frequency and drives the second display area by using a second driving frequency. During the multi-frequency mode, when the second driving frequency changes from a first frequency to a second frequency, the driving controller drives the first display area and the second display area during at least one frame by using a base frequency, drives the first display area and the second display area during at least one second frame by using an intermediate frequency between the base frequency and the second frequency, and then drives the first display area by using the first driving frequency and drives the second display area by using the second frequency.

A method may include generating, using an oscillator, a first signal having a frequency based on a current; generating a first portion of the current based on the second signal, the first portion of the current having a first frequency characteristic; and generating a second portion of the current based on the second signal, the second portion of the current having a second frequency characteristic. A gain of the first frequency characteristic may vary based on a frequency of the second signal. The first frequency characteristic may include a first gain at a first frequency and a second gain at a second frequency. The first gain may be greater than the second gain, and the second frequency may be greater than the first frequency. A phase of the first frequency characteristic may vary based on a frequency of the second signal.

The invention relates to the technical field of thermal power generating unit frequency modulation, and discloses a thermal power generating unit frequency modulation control method based on deep learning. According to the method, through real-time acquisition and preprocessing of operation data, power grid data, environment data and historical frequency modulation data of a thermal power generating unit, abnormal values and missing values can be effectively removed, amplitude and periodic characteristics of frequency fluctuation are extracted, frequency prediction is carried out by adopting a long-short-term memory network model, and the accuracy of frequency prediction is improved. According to the method, complex time sequence characteristics and dynamic changes can be captured, the prediction precision is remarkably improved, compared with a traditional control method depending on experience, the method has higher adaptability and flexibility, in addition, the needed adjusting amount can be accurately calculated in combination with LSTM output and a PID control strategy, and therefore rapid and accurate frequency adjustment is achieved, and the method is suitable for large-scale popularization and application. The response speed and the adjusting capacity of the thermal power generating unit are improved, the stability and the reliability of the power system are enhanced, and finally efficient and safe power supply is achieved.

A display device which includes a display panel that includes a first display area and a second display area, and a driving controller. During a multi-frequency mode, the driving controller drives the first display area by using a first driving frequency and drives the second display area by using a second driving frequency. During the multi-frequency mode, when the second driving frequency changes from a first frequency to a second frequency, the driving controller drives the first display area and the second display area during at least one frame by using a base frequency, drives the first display area and the second display area during at least one second frame by using an intermediate frequency between the base frequency and the second frequency, and then drives the first display area by using the first driving frequency and drives the second display area by using the second frequency.

A high-frequency power supply system according to the present disclosure includes a first power supply, a second power supply, a first matcher, and a second matcher. The second power supply performs pulse modulation of repeating an ON operation of outputting a second forward wave voltage and an OFF operation of not outputting the second forward wave voltage. The first power supply performs frequency modulation control in a second power supply ON period, and performs frequency offset control of outputting a forward wave voltage having a fundamental frequency obtained by adding an offset frequency to a fundamental frequency in a second power supply OFF period.

Provided in the present invention are a primary frequency regulation dynamic simulation method and apparatus based on a thermal power condensate water throttling strategy, which are used for analyzing the dynamic characteristics of a unit when a power plant executes a primary frequency regulation instruction by means of a condensate water throttling strategy after a power disturbance occurs in a power grid. The dynamic characteristics mainly comprise the characteristics of a steam turbine speed governor system, the characteristics of a variable-frequency condensate pump system, the dynamic heat exchange characteristics of a low-pressure heater and extraction steam, the flow characteristics of an extraction steam pipeline, and the output characteristics of a steam turbine body. A moving boundary method is mainly applied to a heat exchange process between condensate water (a cold fluid) and shell-side extraction steam (a hot fluid) in a low-pressure heater. The heat exchange process between the cold and hot fluids can be divided into a superheated section, a phase change section and a subcooled section on the basis of the aggregation state of the extraction steam. When the moving boundary method is applied to a steam turbine regenerative system, the dynamic variation laws of extraction steam temperature and pressure can be more accurately obtained, and the extraction steam pressure on a low-pressure heater side is a key factor in determining the extraction steam flow rate on a low-pressure cylinder side, and is also critical in determining the instantaneous power increment of a steam turbine. Moving boundary method-based frequency regulation dynamic simulation for thermal power condensate water throttling takes into account relatively comprehensive actual process factors, and only one-dimensional modeling along an axial main flow direction is taken into account, thus combining the advantages of fast and accurate simulation. A fast and accurate simulation method is a prerequisite for implementing power grid frequency security analysis. By mastering the dynamic process of power plant load response from the moment a frequency deviation exceeds a dead band to the moment same returns to the dead band, a foundation can be provided for the primary frequency regulation control of power plants and the frequency security analysis of power grids.

The invention discloses a frequency band extension type composite vibration table control system and method based on MRAC-TVC, and the system and method are applied to a frequency band extension type composite vibration table which comprises a lower-layer low-frequency vibration table, a low-frequency long-stroke servo actuator, an upper-layer high-frequency vibration table and a high-frequency short-stroke servo actuator. The control system comprises a lower-layer low-frequency table control system and an upper-layer high-frequency table control system, the lower-layer low-frequency table control system comprises a lower-layer low-frequency vibration table, a low-frequency long-stroke servo actuator, a low-frequency table inner closed-loop subsystem and a low-frequency table outer closed-loop subsystem; the upper-layer high-frequency table control system comprises an upper-layer high-frequency vibration table, a high-frequency short-stroke servo actuator, a high-frequency table inner closed-loop subsystem and a high-frequency table outer closed-loop subsystem. According to the invention, not only is the robustness of the earthquake simulation vibration table system to cope with the load change under the influence of the dynamic response of the experimental structure increased, but also the experimental structure can be prevented from being damaged too early.

The invention relates to the technical field of protocol conversion, in particular to an E1 / IP video conference protocol conversion device and system, and the system comprises a frame structure mapping module, a signaling adaptation module, a media stream packaging module, a buffer area control module and a synchronous coordination module. According to the invention, the synchronization mark and the load field of the physical layer framing structure are extracted, the maximum transmission unit parameter is combined, the frame packet boundary is accurately identified, the cross-network data positioning accuracy is improved, the call control mapping relation is established based on key field identification, and the session continuity between heterogeneous signaling is enhanced; the audio and video sampling rate and timestamp fundamental frequency are matched and verified, the consistency of media stream transmission time delay is guaranteed, interface throughput and time slot occupation changes are dynamically monitored, a buffer regulation and control instruction is generated, and the data transmission stability under burst flow is improved; the synchronization accuracy of the protocol conversion system in a heterogeneous network environment is realized, and the reliability of real-time services such as video conferences and the like is enhanced.

The invention provides an impact table top optimization method and device based on multi-physics field coupling and a storage medium, and belongs to the technical field of mechanical impact simulation. According to the scheme, an impact table top is modeled, a large number of finite element models are randomly constructed according to a modeled structure model, and the impact table top is optimized; the model simulation system is used for carrying out analogue simulation on each finite element model, and the finite element model with the highest fitness is determined, so that the impact table top can be optimized according to table top parameters corresponding to the finite element models, and the performance requirements of light weight, high fundamental frequency and high strength / rigidity can be met at the same time; therefore, the impact table board can be in an extreme dynamic environment with high energy, transient impact and broadband excitation.

The invention relates to a network analyzer of multi-channel spread spectrum modules and a measurement method thereof. The network analyzer comprises a network analyzer and a plurality of multi-channel spread spectrum modules, the network analyzer is provided with a source port and is used for sending a fundamental frequency signal f0 to the spread spectrum module; each multi-channel spread spectrum module is provided with a reference channel, a transmitting channel and a measuring channel; the reference channel comprises a first frequency multiplier and a first frequency mixer; the transmitting channel comprises a second frequency multiplier, an isolator and a coupler; the measurement channel comprises a third frequency multiplier and a second frequency mixer. According to the invention, the plurality of change-over switches are correspondingly connected with the plurality of multi-channel spread spectrum modules, simultaneous or time-sharing measurement of multiple channels is realized, the measurement efficiency and flexibility are improved, power amplification, amplitude stabilization and power division are carried out on radio frequency signals and local oscillator signals through the multi-channel spread spectrum modules, the coupler is responsible for separating measurement signals from reference signals, and the measurement accuracy is improved. And the highest frequency of the spread spectrum system can reach 1THz.

The invention provides a multi-channel microwave signal generation method and system with a fixed initial phase, and the method comprises the steps: responding to a triggering signal received by a high-speed clock synchronization module after a pre-configured synchronous clock signal is inputted to the high-speed clock synchronization module; the high-speed clock synchronization module generates a sampling clock signal and a logic clock signal based on the synchronous clock signal, responds to the logic clock signal and inputs the logic clock signal to the high-speed controller, the high-speed controller generates a signal description word while triggering signal input, responds to the sampling clock signal and inputs the sampling clock signal to the direct digital frequency synthesis module; and the direct digital frequency synthesis module generates an analog fundamental frequency signal required by the multi-channel microwave signal source based on the signal description word, responds to the analog fundamental frequency signal and inputs the analog fundamental frequency signal to the phase-locked loop device, and the phase-locked loop device outputs a final target microwave signal.

The invention relates to the technical field of life prediction of a permanent magnet in a permanent magnet synchronous motor, and discloses a multi-element segmented degradation modeling and life prediction method for the permanent magnet of the permanent magnet synchronous motor, which comprises the following steps of: firstly, selecting a back electromotive force fundamental frequency amplitude drop rate and a characteristic harmonic content rise rate as degradation characteristic quantities; respectively representing overall and local demagnetization behaviors of the permanent magnet; the method comprises the following steps: acquiring data through an accelerated degradation test, and establishing a segmented Wiener process model to describe stage characteristics of degradation; utilizing a t-Copula function to construct a joint distribution model of the multivariate degradation characteristic quantity; extrapolating model parameters under normal stress by combining an Arrhenius model and a segmentation point-temperature model; and life prediction is carried out by adopting Monte Carlo simulation, and the model precision is verified through an area ratio index and a cross validation method. According to the method, the degradation process of the permanent magnet can be comprehensively and accurately represented, high-precision life prediction is realized, and the method is suitable for reliability evaluation and preventive maintenance of a motor system.

An apparatus, method, and computer program product arranged to determine a communication frequency and communicate with a collision detection device at the determined communication frequency based on collision risk.

A high-frequency power supply system according to the present disclosure includes a first power supply, a second power supply, and a first matcher. The first power supply performs frequency modulation control in a second power supply ON period and performs frequency offset control to output a forward wave voltage VF3 having a fundamental frequency F3 obtained by adding an offset frequency to a fundamental frequency F1 in a second power supply OFF period. An optimum value of an initial phase α of a modulation signal is searched for, and an offset frequency Fos at which a difference between a reflection coefficient ρ11 or load-side impedance Z11 corresponding to a center of a locus and a reflection coefficient ρ12 or load-side impedance Z12 is minimum is searched for, and the fundamental frequency F3 in the second power supply OFF period is set.

The invention discloses a frequency domain spectral line accumulation-based frequency sweeping interference detection method and system, and the method comprises the following steps: obtaining sampling data, carrying out the multi-channel digital channelization of the sampling data, and obtaining a frequency domain signal corresponding to each channel; spectral line accumulation is carried out on the frequency domain signal of each channel, then a noise area and a non-noise area are divided, the position of a bottom noise spectral line is estimated according to the noise area of each channel, and finally a detection threshold is calculated according to the spectral line of the position of the bottom noise spectral line. Taking a frequency range exceeding a detection threshold in the frequency domain signal of each channel as a to-be-detected frequency region; and carrying out sweep frequency interference detection based on the gravity center frequency on the to-be-detected frequency region of each channel, and combining the detection results of the channels to obtain a final sweep frequency interference detection result. According to the method, the calculated amount and complexity of the system can be greatly relieved, and the method has very high practicability in engineering implementation.

The invention relates to the technical field of power electronics, and discloses a self-adaptive compensation method based on a unified power quality conditioner and a photovoltaic power quality adjusting system. The method comprises the following steps: on the basis of a minimum equalization algorithm, updating a weight by utilizing input, an error, a variable step size factor, a convergence time control parameter and a variable leakage factor, and constructing a variable leakage minimum equalization algorithm; based on a variable leakage minimum equalization algorithm, a reference current active component amplitude and a reference current reactive component amplitude are acquired to acquire a three-phase current comprehensive reference value, and the three-phase current comprehensive reference value is compared with a three-phase current measured value to control the parallel static var compensator to realize current compensation; based on a variable leakage minimum equalization algorithm, a fundamental frequency unit average value and a fundamental frequency orthogonal average value are obtained to obtain a fundamental frequency component total amplitude, a three-phase voltage compensation amount and a three-phase harmonic compensation amount are calculated, a three-phase reference injection voltage is generated, and the three-phase reference injection voltage is compared with a three-phase actual injection voltage to control the series static var compensator to achieve voltage compensation.

The invention discloses a power grid frequency modulation method and device based on an offshore wind power cluster, terminal equipment and a storage medium, and the method comprises the steps: calculating an initial frequency modulation capacity less than an expected value according to a frequency modulation capacity demand, a first frequency modulation capacity and a second frequency modulation capacity, and determining the probability that the frequency modulation capacity demand of a power grid cannot be met at present; when it is determined that the initial frequency modulation capacity insufficiency expected value is smaller than a target frequency modulation capacity insufficiency expected value corresponding to the frequency modulation capacity requirement, the frequency modulation proportion is adjusted, so that the initial frequency modulation capacity insufficiency expected value gradually approaches the target frequency modulation capacity insufficiency expected value, and the target frequency modulation proportion that the offshore wind power cluster can just meet the frequency modulation requirement is calculated; and then determining the target frequency modulation capacity of the offshore wind power cluster participating in the power grid frequency modulation. Therefore, by quantitatively estimating the frequency modulation capability of the offshore wind power cluster, the target frequency modulation capacity of the wind power cluster needing to participate in frequency modulation under different frequency modulation capacity requirements is accurately calculated, and the difficulty of power grid frequency modulation is effectively reduced.

The invention relates to a communication method and system based on a LoRa spread spectrum technology. Relates to a communication transmission technology, and solves the problems of low transmission efficiency and high maintenance cost caused by data transmission at a single frequency point. The method comprises the following steps: acquiring a frequency point offset of a communication opposite terminal according to identity information of the communication opposite terminal; superposing the frequency point offset on the basis of the recently updated communication fundamental frequency to obtain a communication frequency point of the communication opposite end; and carrying out data transmission with the opposite communication end according to the communication frequency point. The technical scheme provided by the invention is suitable for LoRa network remote communication, and flexible and efficient data transmission management is realized.

A method and system for generating a logarithmic non-uniform pseudo-random electromagnetic exploration signal including: constructing two or more basic unit signals, according to an exploration requirement, that are stairstep signals obtained by superposing in-phase periodic square wave signals, a frequency ratio between adjacent periodic square wave signals is 2, and the two or more basic unit signals meet the following requirement: if a lowest dominant frequency in a first basic unit signal is a fundamental frequency, lowest frequencies of the remaining basic unit signal are l×2m times the fundamental frequency, where l is an odd number except 1, and m is a natural number; and superposing the two or more basic unit signals to obtain a logarithmic non-uniform 2n sequence pseudo-random signal. A logarithmic non-uniform 2n sequence stairstep signal is constructed within a limited frequency interval, and requirements of prospectors for a higher frequency density within a specific frequency interval are met.

The invention provides a two-degree-of-freedom fundamental frequency modulation method and device of a multi-level current source converter. And triggering each bridge arm in the multi-level current source converter by adopting a fundamental frequency modulation mode according to a preset first degree of freedom and a preset second degree of freedom under the condition that the terminal voltage of the U-phase filter capacitor has a zero crossing point moment. On the basis of the first degree of freedom and the second degree of freedom, the switching speed of a semiconductor device on a bridge arm in the multi-level current source converter can be reduced by adopting a fundamental frequency modulation mode, and the harmonic quality of the multi-level current source converter is greatly improved, so that the operation loss of the multi-level current source converter is reduced, and the service life of the multi-level current source converter is prolonged. And the sampling cost and the control cost of the sensor are reduced. The multi-level current source converter can realize decoupling of voltage and power, so that the operation of the multi-level current source converter is more flexible and efficient.

The invention discloses a high fundamental frequency permanent magnet motor low carrier wave ratio control method and device based on an optimal switching vector mode. The method comprises the steps of sampling a motor current and a rotor position, and obtaining a dq-axis reference current; calculating a reference stator flux linkage, a reference modulation ratio and a reference voltage phase angle; looking up the table according to the carrier wave ratio and the reference modulation ratio to obtain an optimal switching vector mode and an optimal flux linkage apocentric distance of offline optimization; determining an optimal switching vector mode of the current control time domain; calculating an optimal reference stator flux linkage; calculating a reference voltage vector according to sampling and calculation delay; calculating a switching vector sequence and action time; a switching signal is generated. Through off-line optimization, on-line table look-up and real-time synthesis calculation of the optimal switching vector mode, low-current harmonic and high-dynamic response control of the permanent magnet motor under a low carrier wave ratio is realized, the complexity of a control algorithm is simplified, and the efficiency and reliability of the system are improved.

The invention relates to a resonance peak ratio-based single-phase earth fault line selection method for a resonance grounding system, and belongs to the technical field of power system relay protection. The method comprises the following steps of: calculating zero-sequence current data within one tenth of a fundamental frequency period after a fault starting moment of each line; performing Fourier transform on the zero-sequence current of each line to obtain a spectrogram; for each line, determining a resonance peak and a resonance peak in the spectrogram by using a local peak detection algorithm; calculating the harmonic peak coefficient of each line and the average slope of two maximum harmonic peaks before and after the boundary; the resonance peak value ratio of each line is obtained; and finally, determining a fault line by judging whether the resonance peak value ratio meets the criterion or not. The key point is to detect the significant difference between the harmonic peak coefficient after the fault and the average slope of the two maximum harmonic peaks, and the method has the advantages of strong adaptability, high line selection accuracy, easy engineering realization and the like.