30 results about "Harmonic attenuation" patented technology

The invention provides a parameter designing method of an LCL filter of a grid-connected inverter. The parameter designing method of the LCL filter is based on the bridge arm output voltage rejection ratio. On the basis that an inverter structure and a modulation mode are determined, by selecting the harmonic attenuation proportionality coefficient at harmonic frequency and inverter switch frequency, the requirement for guaranteeing the filtering performance of LCL is met. Meanwhile, through optimized design, the values of filter inductance and filter capacitance are minimum, the designing method is visual and effective, the steps of error-and-try repeating are omitted, and easiness and quickness are achieved.

The invention provides a software radio receiver circuit. The software radio receiver circuit comprises a low-noise radio-frequency front end circuit, a high-linearity radio frequency front end circuit, a harmonic attenuation radio frequency front end circuit, a common analog intermediate-frequency circuit, a local oscillator signal generation circuit, a biasing circuit and a control circuit. One end of the low-noise radio-frequency front end circuit is connected with the first end of the common analog intermediate-frequency circuit after the low-noise radio-frequency front end circuit is connected with the high-linearity radio frequency front end circuit in parallel. One end of the harmonic attenuation radio frequency front end circuit is connected with the first end of the common analog intermediate-frequency circuit .The local oscillator signal generation circuit is connected with the low-noise radio-frequency front end circuit, the high-linearity radio frequency front end circuit and the harmonic attenuation radio frequency front end circuit. The biasing circuit is used for providing a reference bias voltage and a reference bias current for the software radio receiver circuit. The control circuit is used for controlling work modes of the software radio receiver circuit. The software radio receiver circuit can meet the requirements of various application environments.

The invention discloses a method for optimizing excitation modes in transient flow-based pipeline tiny leakage detection. The optimizing method comprises the following steps of: building a pipeline leakage system model through Flowmaster software and selecting various component parameters; exploring the influence of excitation point positions on positioning accuracy in harmonic attenuation method-based leak detection; and exploring the influence of valve actuation time of pulse signals, amplitude of the pulse signals and waveform of excitation signals on the positioning accuracy in the harmonic attenuation method-based leak detection. According to the method disclosed by the invention, factors such as the positions of excitation points, the valve closing time, the amplitude of the excitation signals, the waveform of the excitation signals and the like are changed in the model to find an excitation mode which is least in the influence on the normal operation of a pipeline and most accurate in the measurement result.

The invention discloses a method and system for processing the relay protection setting value of a nuclear power plant generator-transformer unit. The method for processing the relay protection setting value of the nuclear power plant generator-transformer unit includes the following steps that S1, a first initial setting value of the main transformer zero-sequence differential slope of a generator of the generator-transformer unit and a second initial setting value of differential protection second harmonic intersecting lock time are collected; S2, the actuation time T1 of a main transformer zero-sequence differential protection switch is detected, when T1 is larger than a preset value T, the first initial setting value is optimized, and the actuation time T1 of the main transformer zero-sequence differential protection switch is made to be smaller than the preset value T; whether three-phase second harmonic attenuation time constants of the generator are the same or not is detected, when the three-phase second harmonic attenuation time constants are not the same, the second initial setting value is optimized, and the three-phase second harmonic attenuation time constants are made to be the same; S3, the optimized initial setting value is sent to a control system of the generator-transformer unit. The method and system have the advantage that the stability and the safety of the generator-transformer unit are improved.

The embodiment of the invention discloses a harmonic attenuation method and a circuit. The method and the circuit are used for solving the problem of interference of different-order harmonics during a down-conversion process. The method provided by the embodiment of the invention comprises the steps: respectively inputting a same radio-frequency signal to a first active link and at least one path of second active link of a harmonic attenuation circuit; performing adjustment and phase shift on the radio-frequency signal inputted to the first active link by a first phase shifter, and then performing the down-conversion on the radio-frequency signal and a local oscillating signal inputted to a first down-converter; performing adjustment and phase shift on the radio-frequency signal inputted to the second active link by a second phase shifter, and then performing the down-conversion on the radio-frequency signal and the local oscillating signal inputted to a second down-converter; and lastly, adding the radio-frequency signals of all active links by an adder of the harmonic attenuation circuit, thereby efficiently attenuating the different-order harmonics.

The invention relates to the technical field of oil exploration, and particularly relates to a slip-sweep harmonic suppression method and device. The method comprises the following steps: acquiring slip-sweep relevant post data, and picking up the first arrival time of the relevant post data; performing complementary ensemble empirical mode decomposition (CEEMD) on the relevant post data to obtain a group of intrinsic mode function (IMF) components; analyzing the distribution condition of harmonic in the IMF components, and determining the IMF components containing the harmonic and the IMF components not containing the harmonic; performing harmonic attenuation on the IMF components containing the harmonic from the first arrival time; and reconstructing the IMF components after harmonic attenuation and the IMF components not containing the harmonic to obtain harmonic-removed relevant post data. The method and the device effectively suppress the slip-sweep harmonic without focal force signals, and improve the signal-to-noise ratio of seismic data.

The invention relates to a method for judging harmonic stability of a high-voltage direct-current power transmission system. The method for judging the harmonic stability of the high-voltage direct-current power transmission system comprises the following steps of (1) obtaining an H matrix of a converter equivalent two-port network; (2) using a switch function to deduce an H matrix parameter expression; (3) using the H matrix to enable the high-voltage direct-current power transmission system connected with a converter to be equivalent to a simple RLC circuit, and obtaining a harmonic attenuation factor Re(Zcondc+Zdch), wherein, if the Re(Zcondc+Zdch) is smaller than or equal to zero, it is determined that harmonic waves are unstable, if the Re(Zcondc+Zdch) is equal to zero, it is determined that the high-voltage direct-current power transmission system is in a critical unstable state, and if the Re(Zcondc+Zdch) is larger than zero, it is determined that the high-voltage direct-current power transmission system is stable. According to the method for judging the harmonic stability of the high-voltage direct-current power transmission system, the conception is clear and the judgment method is easy and effective in the judgment process, the phenomenon that the high-voltage direct-current power transmission system is unstable can be effectively prevented from occurring by modifying related device parameters in the design stage of HVDC.

The invention discloses an isolation method and system based on MGP grid-connected harmonic waves of a new energy power grid, and the method comprises the steps: connecting a frequency converter intoa power feedback control device, starting the frequency converter, and driving an MGP to operate at a synchronous rotating speed; detecting voltages on two sides of grid connection, closing the gridconnection switch after a grid connection condition is met, and enabling the MGP to operate in a grid connection manner; respectively measuring voltage waveforms of the measuring point 1 and the measuring point 2 under different working conditions and storing measurement result data; and performing Fourier transform on the measuring point 1 and the measuring point 2 by using the different workingconditions, obtaining spectrogram data by combining a 50HZ fundamental wave amplitude, and analyzing the isolation effect of the MGP on harmonic waves according to the measurement result data and thespectrogram data. The new energy power grid harmonic waves are isolated through the MGP system, the power feedback control system and the voltage feedback control system, the MGP system can isolate the generated harmonic waves under different working conditions, the harmonic waves are attenuated, and the operation stability of the new energy power grid is improved.

A radio frequency (RF) switch apparatus includes a signal input terminal; a signal output terminal; a first transistor including a first input terminal connected to the signal input terminal, a first output terminal connected to the signal output terminal, a first gate terminal, and a first body terminal, wherein one of the first input terminal and the first output terminal is a source terminal and another one of the first input terminal and the first output terminal is a drain terminal; a first capacitor circuit connected between the first input terminal and the first body terminal; and a second capacitor circuit connected between the first body terminal and the first output terminal; wherein a first capacitance of the first capacitor circuit is greater than a second capacitance of the second capacitor circuit.

The invention discloses an output filter applied to open winding transformer type dual inverters. The output filter comprises three-phase inverters 1 and 2 on the primary side of an open winding transformer, three-phase filtering electric reactors L3 and three-phase filtering capacitors C on the secondary side of the open winding transformer, wherein one ends of the three-phase filtering electric reactors L3 are connected with the secondary sides of the three-phase windings of the open winding transformer respectively while the other ends of the three-phase filtering electric reactors L3 are used as filter output to be connected with a power grid; the filter also comprises at least one group of primary side three-phase filtering electric rectors which consist of three primary side three-phase filtering electric rectors; and one ends of the three primary side three-phase filtering electric rectors are connected with three-phase output bridge arms of the three-phase inverter 1 or the three-phase inverter 2 respectively while the other ends of the three primary side three-phase filtering electric rectors are connected with the primary side three-phase terminals or separating side three-phase terminals of the three-phase windings of the open winding transformer respectively. According to the output filter, the characteristic that the output voltage harmonics of the two inverters are counteracted of the open winding transformer type dual inverter topology is fully utilized by combination with relatively high harmonic attenuation capability of the LCL filter, thereby greatly reducing the usage amount of filtering inductors and lowering the cost of the filter.

A signal processing device includes a plurality of harmonics attenuation filters configured to have different bandpass characteristics and configured to generate signals to be used for estimation of a fundamental frequency of an input signal by restricting the bandwidth of the input signal. Each of the harmonics attenuation filters comprises a filter that has an accumulator and a comb filter which are connected in cascade. The accumulator is configured to accumulate input signals thereto. The comb filter is configured to output a difference between an input signal to the comb filter and a signal obtained by delaying the input signal to the comb filter.

The invention provides a design scheme of a three-phase to nine-phase step-up step-down auto-coupling phase-shifting transformer. Secondary side windings are successively displaced by an electrical angle of 20 degrees. The secondary side 20-degree winding and a 20-degree winding are symmetric about its 20-degree winding axis, so a 20-degree voltage vector and a 20-degree voltage vector are symmetric about a voltage vector. The scheme has less additional winding turns of the three windings on the secondary side (20 degrees, 0, 20 degrees), good symmetry, and a resultant magnetic potential closer to a sine wave. A primary winding side has a good current low-order harmonic attenuation effect. The phase-shifting transformer with the auto-coupling structure has a design capacity only about 10%of a phase-shifting transformer of isolation structure, which can greatly reduce manufacturing cost.

The invention discloses a prompt-neutron-attenuation-constant obtaining method. The prompt-neutron-attenuation-constant obtaining method includes the following steps that periodic pulse neutrons are injected into a subcritical reactor through a pulse neutron source; in a target pulse period, neutron counting rate time spectrums of different positions in the subcritical reactor are obtained; specific values of the obtained neutron counting rate time spectrums of the different positions are computed, and relative neutron counting rate time spectrums are obtained; through the relative neutron counting rate time spectrums, a target moment when prompt-neutron higher-order harmonic attenuation is completed is determined; in the target pulse period, the neutron counting rate between the target moment and an ending moment of the pulse period is subjected to exponential attenuation fitting processing, and a prompt-neutron fundamental-wave attenuation constant is obtained. The more-accurate prompt-neutron fundamental-wave attenuation constant under the condition that interference of prompt-neutron higher-order harmonic waves does not exist can be obtained. The invention also discloses a prompt-neutron-attenuation-constant obtaining device, equipment and system and a readable storage medium, and the prompt-neutron-attenuation-constant obtaining device, equipment and system and the readable storage medium have corresponding technical effects.

The embodiment of the invention provides a radio frequency control circuit and electronic equipment. The radio frequency control circuit comprises a baseband controller, a wireless fidelity link and aharmonic attenuation module. The wireless fidelity link comprises a receiving sub-link, a transmitting sub-link and a first selection switch, and the receiving sub-link and the transmitting sub-linkare connected with a first end of the first selection switch; the harmonic attenuation module is connected with the wireless fidelity link; the harmonic attenuation module and the wireless fidelity link are respectively connected with the baseband controller; the baseband controller is used for controlling the harmonic attenuation module and the wireless fidelity link to be connected or disconnected according to the on-off state of the first selection switch and the transmitting sub-link, the transmitting sub-link is used for transmitting a radio frequency signal generated by the baseband controller, and the harmonic attenuation module is used for attenuating second harmonics in the radio frequency signal. In the embodiment of the invention, the wireless fidelity link and the 5G link can coexist to work, the frequency of the 5G link does not need to be reduced, and the user experience is improved.

The invention relates to a phase-locked loop control circuit based on a second-order oscillation link under high permeability, and belongs to the field of electronic circuits. A function relationship between an output phase angle of the phase-locked loop and a disturbance quantity is utilized to reveal a main reason for system robustness reduction, and main defects of a traditional pre-filter phase-locked loop are analyzed. Therefore, a novel phase-locked loop design scheme based on a second-order oscillation link is provided, an equivalent transfer function of the novel phase-locked loop is deduced, and meanwhile a specific parameter design method is provided. Theoretical analysis shows that the novel phase-locked loop has the same harmonic attenuation characteristic as that of a traditional preposed second-order low-pass filter phase-locked loop, the system robustness is guaranteed, and grid-connected common point unity power factor network access can be achieved without an additional phase compensation link. And finally, verifying the effectiveness of the novel phase-locked loop design scheme through a simulation result.

The invention provides a terminal performance improvement circuit and a mobile terminal. The terminal performance improvement circuit is applied to a radio frequency circuit with a DC component and comprises a radio frequency module and an LC series resonance circuit, wherein the radio frequency module is provided with a nonlinear device; the LC series resonance circuit is used for carrying out attenuation processing on harmonic wave except for fundamental wave, one end of the LC series resonance circuit is connected to the output end of the radio frequency module and the other end of the LC series resonance circuit is connected to a radio frequency back-end circuit. Through the LC series resonance circuit, the attenuation processing on the harmonic wave except for the fundamental wave is realized, the enough harmonic attenuation effect is guaranteed while the number of components in the circuit is reduced, the circuit volume is reduced, and the convenience is provided for assembly of the components and system optimization.

The invention discloses an inverter grid connected harmonic suppression system based on an error transfer function algorithm. The system comprises a power grid voltage sensor, a current generator, a power grid current sensor, a PR harmonic resonance controller, a monopole SPWM, an IGBT power switching tube, an LC filter and an MCU, the power grid voltage sensor is connected with the current generator, the current generator is connected with the PR harmonic resonance controller, the power grid current sensor is connected with the PR harmonic resonance controller, the PR harmonic resonance controller is connected with the monopole SPWM, the monopole SPWM is connected with the IGBT power switching tube, the IGBT power switching tube is connected with the LC filter, and the LC filter is connected with a power grid. All interference is regarded as system total noise, the PR harmonic suppression algorithm is connected in parallel on the basis of the PR base wave resonance algorithm, according to an fft determined error transmission function, the gain, the center frequency point and the bandwidth of the PR harmonic suppression algorithm are determined, a pulse response invariance method is adopted for dispersing the fft determined error transmission function, the whole system reaches the 20 db or more harmonic attenuation rate.

The invention relates to a pipeline leakage detection positioning method based on coupling of negative pressure waves and a harmonic attenuation method. The method comprises the following steps: S1, detecting leakage by using a negative pressure wave method, positioning an initial leakage position, and isolating the initial leakage pipeline position; S2, applying excitation to an isolated pipeline, generating transient flow, and using a dynamic pressure sensor for continuously measuring and recording pressure signals at a position in the pipeline after the excitation is applied; S3, dividing the collected pressure signals into different periods; S4, performing Fourier transform on the signals divided into the different periods to obtain a signal frequency spectrum in each period, extracting intensity of each harmonic wave in the different periods, and then performing exponential fitting to obtain an attenuation rate of each harmonic wave; and S5, according to the attenuation rate of each harmonic wave obtained after the fitting, further performing calculation to obtain a positioning result. According to the invention, positioning of tiny leakage detection is realized, the positioning is accurate, and the feasibility is high.

The invention discloses an order increasing grid-connected converter transient state network voltage feed-forward item low-pass filter method, wherein an order increasing algorithm is enabled by capturing a network voltage transient point; quick response to a network voltage feed-forward item in a transient process is realized and meanwhile increasing of a harmonic attenuation coefficient along with the passage of time at a voltage transient moment is realized when low-pass filter is performed on each component of positive and negative sequence voltage of a synchronous rotary direct current coordinate system; and quick and accurate acquisition of the network voltage feed-forward item in a positive and negative sequence control equation of the synchronous rotary direct current coordinate system is realized.

The invention provides a software radio receiver circuit. The software radio receiver circuit comprises a low-noise radio-frequency front end circuit, a high-linearity radio frequency front end circuit, a harmonic attenuation radio frequency front end circuit, a common analog intermediate-frequency circuit, a local oscillator signal generation circuit, a biasing circuit and a control circuit. One end of the low-noise radio-frequency front end circuit is connected with the first end of the common analog intermediate-frequency circuit after the low-noise radio-frequency front end circuit is connected with the high-linearity radio frequency front end circuit in parallel. One end of the harmonic attenuation radio frequency front end circuit is connected with the first end of the common analog intermediate-frequency circuit .The local oscillator signal generation circuit is connected with the low-noise radio-frequency front end circuit, the high-linearity radio frequency front end circuit and the harmonic attenuation radio frequency front end circuit. The biasing circuit is used for providing a reference bias voltage and a reference bias current for the software radio receiver circuit. The control circuit is used for controlling work modes of the software radio receiver circuit. The software radio receiver circuit can meet the requirements of various application environments.