182 results about "Base frequency" patented technology

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.

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 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.

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 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 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.

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 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.

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.

A method for identifying the dynamic behavior of a non-rigid object (10), the object being fixedly attached to a platform (12) that can be set in motion by an actuation device (14) is proposed. The method comprises actuation of the drive device (14) so ​​as to impart to the object a predefined periodic movement at a frequency, called the "cycle frequency". The periodic movement is a combination of at least two geometrically independent periodic elementary movements. The method comprises recording during actuation the variation of at least one quantity representative of a dynamic behavior, called the "dynamic quantity", and calculating for each of the cycle frequencies of the components called "elementary components", a Fourier transform of the variation of said at least one dynamic quantity for each elementary frequency.A dynamic behavior of the object is determined based on the variation of the elementary components. Abstract figure: Figure 2.

The application relates to the field of laser technology, in particular to a device and a method for generating wide-tuning narrow-line-width mid-infrared laser, wherein the pump light emitted by a nanosecond pulse OPO base frequency pump source is reflected to a beam splitter by a full reflection mirror after passing through a first adjuster; the pump light emitted by a continuous wave OPO base frequency pump source is irradiated to the beam splitter after passing through a second adjuster; the two beams of pump light are combined after passing through the beam splitter, are focused after passing through a plano-convex lens, are irradiated to a first plano-concave full reflection mirror, and then are transmitted to a nonlinear crystal to generate signal light and idler mid-infrared laser through nonlinear frequency conversion; the idler mid-infrared laser and the residual pump light are transmitted to a doublet mirror and are separated by the doublet mirror; the signal light is reflected to the nonlinear crystal in sequence through a second plano-concave full reflection mirror, a first plane full reflection mirror, a second plane full reflection mirror and the first plano-concave full reflection mirror, and an oscillation closed loop is formed. The application realizes that the pulse OPO outputs a pulse with a line width less than 90 MHz in the tuning range, and the extraction efficiency of the idler light is as high as 9.3%.

The invention discloses a wind turbine generator frequency modulation control method based on inertia requirements. The method comprises the following steps: analyzing main factors influencing system frequency response characteristics; according to an analysis result, taking the frequency change rate as a constraint, and carrying out system minimum inertia demand evaluation; according to an analysis result, performing system minimum inertia demand evaluation by taking the maximum frequency offset as a constraint; the maximum value of the two constraints is adopted as the minimum inertia demand of the system, so that the sufficient inertia of the system is ensured, and the frequency stability of the system is improved; and constructing a target function according to the results to obtain the output power of the wind turbine generator, and participating in system frequency modulation. In order to solve the problems that the existing comprehensive inertia simulation synchronous machine control is insufficient and the consideration factors of the system minimum inertia evaluation are not comprehensive, a wind turbine generator rotor kinetic energy optimal frequency output power control scheme based on the system minimum inertia demand is provided, and the flexibility and plasticity of the wind turbine generator converter control output power are fully exerted. And the system frequency stability is enhanced.

An impedance matching circuit for a plasma process supply system and a plasma process system, configured for powers≥500 W and frequencies in a range from 2 MHz to 100 MHz, the impedance matching circuit including a matching unit having one or more reactances and a resonator. The impedance matching circuit is configured for operation at a predetermined high frequency (HF) power signal with a predetermined basic frequency and auto-frequency tuning (AFT) bandwidth, limited by a predetermined upper AFT frequency and a predetermined lower AFT frequency. The resonator is configured to not influence the HF power signal at the predetermined basic frequency and to damp the HF power signal and / or influence the HF power signal in a phase at both the predetermined upper and lower AFT frequencies.

The application discloses a frequency offset estimation method and device based on LoRa modulation, a medium, and a frequency offset estimation device. The method comprises the following steps: estimating a decimal multiple frequency offset based on an upper chirp signal in a received chirp signal, and compensating the received chirp signal based on the decimal multiple frequency offset to obtain a compensated chirp signal; determining a first upper chirp signal and a first lower chirp signal from the compensated chirp signal, and the decimal multiple frequency offset is obtained based on the upper chirp signal in the chirp signal; determining a first position with the largest correlation peak of the first upper chirp signal and a reference upper chirp signal, and a second position with the largest correlation peak of the first lower chirp signal and a reference lower chirp signal; and estimating a target frequency offset based on the first position, the second position, and the decimal multiple frequency offset. The method can improve the accuracy of frequency offset estimation, reduce the influence of timing deviation on the accuracy of frequency offset estimation, improve the accuracy and precision of timing synchronization, and further improve the demodulation performance of a LoRa received signal.

Technological advancements are disclosed that utilize inertial sensor data for multiple classes to select a combination of filters to extract information though features to train a machine learning core decision tree. A determination is made whether the data for a class includes a frequency peak or dominating frequency that contains significant information about the class. In response to the data for the class including a frequency peak, a peak-based frequency range is determined. An entropy value is calculated for multiple frequency ranges in the data for the class. An entropy-based frequency range is selected from the multiple frequency ranges having a minimum entropy value. A frequency of interest is selected from the peak-based frequency range and the entropy-based frequency range for the class. A combination of filters is selected for each frequency of interest for each class and a decision tree is trained based on selected filter combination.

The invention provides a frequency modulation nonlinear correction method based on frequency domain phase shift asynchronous resampling. The method is realized based on a sweep frequency interference measurement device, and the method utilizes signals detected by two balance detectors to carry out a series of calculations so as to determine a target distance. According to the method, the problem that in an existing synchronous resampling frequency modulation nonlinear correction method, the nonlinear correction effect is not ideal due to the fact that the optical frequency of the auxiliary interferometer and the optical frequency of the measurement interferometer are not synchronous can be solved, correction can be more accurate through frequency domain phase shift resampling, and the correction effect is not limited by the sampling rate.

The present application relates to the technical field of geophysical electromagnetic exploration data processing, and specifically discloses a kind of orthogonal digital phase-sensitive detection time-frequency electromagnetic complex response extraction method, automatically extracts base frequency and initial phase using transmitter stored time-stamped current data, constructs zero initial phase orthogonal reference signal, carries out two-way digital phase-sensitive detection to receiver full waveform sampling data, obtains in-phase component and quadrature component, so as to calculate the complex response amplitude and phase information of target frequency.The present application does not need analog phase-locked loop and artificial phase modulation process, can stably extract complex response parameters under strong interference and strong noise background, is especially suitable for array time-frequency electromagnetic receiver full waveform sampling data post-processing, without transmitting current waveform to each receiving node in real time, improves the flexibility and scalability of time-frequency electromagnetic system.

The application discloses a high-power laser beam inter-delay measurement device, when the relative time delay is measured in a base frequency band, a signal emitted by a clock reference is connected to a first channel of a high-speed oscilloscope in an electrical signal mode, and a pulse output by a main laser system with a high repetition frequency is received by a first photoelectric tube and converted into an electrical pulse and connected to a second channel of the high-speed oscilloscope; when the relative time delay is measured in a three times frequency band, three times frequency analog light is received by a second photoelectric tube after passing through terminal optical elements and converted into an electrical pulse and connected to a third channel of the high-speed oscilloscope. The application measures the time delay by segmenting and dividing wavelengths, and finally accumulates the total delay to determine the time delay of each light beam relative to the reference at a target point. The high-precision measurement of the inter-beam delay can be realized without adding new equipment by using the existing main laser system with a high repetition frequency, three times frequency analog light source and other equipment, the principle and structure are simple, the cost is low, and the engineering implementation is easy.

The invention discloses an automatic tobacco cutting flow control method, belongs to the technical field of tobacco processing, and mainly aims to improve the tobacco cutting quality stability, enable the tobacco cutting process to be continuously and efficiently carried out, and avoid the problem that a tobacco cutter and auxiliary connection equipment are frequently started and stopped. According to the main technical scheme, the automatic shredding flow control method comprises the steps that the basic frequency of a feeding device is determined; responding to the adjusting instruction, and controlling the running state of the tobacco cutter; and the operation state of the feeding device is controlled.

The application discloses an infrared image denoising method, computer equipment, medium and product, and relates to the technical field of image processing. The method comprises the following steps: firstly, constructing a structure tensor matrix corresponding to each pixel point in the infrared image through horizontal and vertical pixel gradient matrices; then, realizing separation of a base frequency component and a high frequency component of the infrared image based on an anisotropy measurement map, processing the main structure and the detail information respectively, and avoiding problems such as detail loss or noise residue caused by the traditional denoising method. In the high frequency component processing, the high frequency noise is efficiently filtered through the steps of overlapping block division, structure similarity reference sub-block screening, three-dimensional block group singular value decomposition and adaptive threshold shrinkage, and the integrity of the detail information is ensured by means of sub-block stacking and inverse transformation reconstruction. Finally, the fusion of the base frequency component image and the denoised high frequency component image ensures that the output image has clear main structure and retains key details such as edges and textures.

The invention discloses a resonance network for suppressing transient recovery voltage of a circuit breaker, and belongs to the technical field of high-voltage alternating-current circuit breaker switching-on and switching-off. The resonance network is composed of a metal oxide arrester and N resonance branches with the same structure. The number N of the resonant branches and the resonant frequencies of the resonant branches are obtained through an electromagnetic transient simulation model; the resonant frequency presents low impedance near the transient recovery voltage fundamental frequency, a shunt and energy consumption path is provided for the high-frequency oscillation current, and active suppression of the rising gradient and the oscillation amplitude of the transient recovery voltage is achieved. The metal oxide lightning arrester is used as backup protection, and clamps the transient recovery voltage peak value when the suppression effect of the resonance branch is insufficient or abnormal. The resonant network can significantly suppress the rise rate and amplitude of transient recovery voltage under a high voltage level in a medium strength recovery critical period, effectively improves the on-off reliability of the vacuum circuit breaker, and has good working condition adaptability and system safety.

The invention discloses a bridge-based frequency division duplex balanced low noise amplifier and a radio frequency receiver, comprising a bridge A and a bridge B. The bridge A and the bridge B are both dual-frequency bridges, a port P1 of the bridge A receives signals, a port P4 of the bridge A is connected with a load, a port P2 and a port P3 are respectively connected with an input end of the low noise amplifier, and a port P2 and a port P4 of the bridge B are respectively connected with an output end of the low noise amplifier. The output end of the low noise amplifier is respectively connected with a port P5 and a port P8 of the bridge B, a port P6 outputs a frequency f1 signal, a port P7 can output a frequency f2 signal, or the port P6 outputs the frequency f2 signal, and the port P7 outputs the frequency f1 signal; the output ports of the bridge A are opposite in phase, and the output ports of the bridge B are the same in phase; and the duplex effect is realized under the working of the two bridges. Compared with the design of a traditional balanced duplex low-noise amplifier, an additional traditional duplexer is not needed to realize a duplex function, so that the system integration level is improved, the component cost is reduced, and the system performance is improved.