96results about How to "Low sampling frequency requirement" patented technology

The invention discloses a co-channel full-duplex system based on MPPSK modulation. After the system isolates receiving and sending signals at the radio-frequency head normally, cancellation conducted on leakage self-interference signals is finished on a digital baseband; the cancellation method is conducted after conducting shock filter on MPPSK receiving and sending aliasing signals, extracting and multiplying by coherent carrier, band-pass filtering and digitizing, the result of initial channels of all self-interference channels between the output end of a modulator and a receiver ADC is estimated before formal communication, self-interference offset signals are rebuilt by the adoption of the estimated result, further residual errors are filtered out with the combination of methods of coding rate filtering and double matched filtering of a method of shock filtering-multiplying by the coherent carrier-band-pass filtering-coherent demodulation, and MPPSK receiving signals are demodulated reliably. The co-channel full-duplex system based on MPPSK modulation is free of radio-frequency self-interference cancellation, has low requirements for the dynamic range and sampling rate of the ADC, has high isolation degree for the self-interference signals, and is simple in structure, low in complexity, high in spectrum efficiency and good in demodulation performance.

The present invention discloses a non-intrusive resident load identification method based on S_Kohonen. The method comprises the steps: the step 1: determining a switching event according to the changing of an active power at a home electric power inlet, and when the switching event happens, collecting current samples of electric appliances having generation of the switching events at the home electric power inlet; the step 2: performing frequency-domain analysis of the collected electric appliance current samples, extracting the frequency-domain harmonic amplitudes of the collected electric appliance current samples as load features of each electric appliance, and forming a load feature base; the step 3: designing an S_Kohonen neural network suitable for resident load identification, and determining the number of nerve cells of the input layer and the output layer of the S_Kohonen neural network and the scale of the competition layer to determine a selection mode for obtaining the nerve cells and a learning algorithm of weight regulation; the step 4: performing parameter initialization; the step 5: performing training of the S_Kohonen network through a training set and performing test of the training set; and the step 6: regulating the network parameters to realize optimal network performances.

The invention discloses an image sensor which comprises a pixel array module formed by multiple pixel groups, multiple switch control modules, a variable gain amplifier, an assembly line ADC and a decoding module, wherein each pixel group comprises multiple pixels which constitute at least one unit pixel, each switch control module corresponds to one line of the pixel array module in configuration and comprises a first gating circuit and a second gating circuit, the variable gain amplifier processes output signals of the first gating circuits and output signals of the second gating circuits, the assembly line ADC carries out analog-to-digital conversion on the signals output by the variable gain amplifier, and the decoding module controls the first gating circuit and the second gating circuit of each line to be alternately read, outputs signals of various unit pixels of each line and controls the first gating circuits and the second gating circuits so that the signals of various unit pixels read by the decoding module can be sequentially output to the variable gain amplifier. The image sensor can save the map area and breaks through height restriction of multiple analog-digital converter maps.

The present invention relates to a frequency modulation waveform marking method of time difference method ultrasonic flowmeter, and is used to measure the transmitting time of an ultrasonic signal in the fluid medium, thereby measuring the flow speed and the flow capacity of medium. The method provided by the invention has the following procedures: (1) frequency variation is overlaid on transducer operating frequency to form an emitting signal; (2) the emitting signal carries the information of flow speed when the fluid medium transmits; (3) signals are collected on a receiving transducer terminal; the frequency variation signals are demodulated and have related calculation with the original frequency variation signals in the procedure one; (4) according to the related function peak value, the signal transmitting time is calculated to gain the flow speed and the flow capacity. The frequency variation provided by the invention can be achieved through overlaying frequency deviation on transducer resonance central frequency; the frequency after overlaid is in the operation bandwidth of the transducer; the invention has the advantages of having no interference by signal amplitude fluctuation and flow and of achieving the signal transmitting time with high measuring precision.

The invention discloses an online monitoring method for degradation of an insulated gate bipolar transistor (IGBT). The online monitoring method can be used for monitoring the degradation degree of the IGBT in actual operating process, so as to send out early warning before the IGBT fails. The online monitoring method comprises the steps of: under the condition that the IGBT does not degrade, conducting a temperature experiment on an IGBT to be monitored, measuring junction temperature indexes (invariant voltage drop) representing IGBT junction temperature levels at different junction temperatures of the IGBT to be monitored and degradation indexes (conductive resistance) representing IGBT degradation degrees, and calculating a proportionality coefficient of degradation index variable quantity and junction temperature index variable quantity under the same junction temperature variation; and under the condition that the IGBT degrades, measuring a junction temperature index and a degradation index online, carrying out optimization of removing junction temperature influence on the degradation index by combining with the proportionality coefficient obtained through the temperature experiment under the normal condition, and monitoring the degradation degree of the IGBT to be monitored according to the optimized degradation index.

The invention relates to a distribution network fault line selection method based on extensional fusion of pattern spectrum analysis and morphological peak and valley detection, and belongs to the technical field of electrical power system relay protection. When a single-phase ground fault happens to a resonant grounded power distribution network, the fault line selection method with the pattern spectrum analysis has the good line selection effect on a fault with a small initial phase angel, and the fault line selection method with peak and valley detection of each feeder zero-sequence current in the feature frequency band has the good line selection effect on a fault with a large initial phase angel. The initial phase angles are calculated, the extension theory is combined, extensional fusion is carried out on the two line selection methods with the fault initial phase angles as weight distribution factors, and symbols relevant to confidence coefficients are used as criterions to achieve fault line selection. Specific examples and a large number of simulation experiments show that the method has applicability and reliability on different fault lines, fault distances, transitional resistances and fault initial phase angles.

The invention provides a fault line selection method for a resonant grounded power distribution system by pattern spectrum. When the resonant grounded power distribution system has a single phase fault, the zero sequence current of each line can be increased suddenly; and at the instant of the fault, the direction of the zero sequence current of a fault line is opposite to that of a perfect line; therefore, the zero sequence current of each line is subjected to multi-scale morphological operation firstly, and then the pattern spectrum of the zero sequence current is derived; after the fault line has a fault, the pattern spectrum of the first-half wave zero sequence current is mainly distributed in the positive scale, while after the perfect line has a fault, the pattern spectrum of the first-half wave zero sequence current is mainly distributed in the negative scale; therefore, positive scale spectral values and negative scale spectral values of the pattern spectrum of the zero sequence current of each line are respectively summed, and then a ratio of the sum of the positive scale spectral values to the sum of the negative scale spectral values of the zero sequence current of each line is respectively calculated; and a line with the maximum ratio is the fault line, otherwise, the bus fault is judged. The method has strong antijamming capacity, is not influenced by fault close angle and transition resistance, has low requirement on sampling frequency of signals, and has the advantages of convenient realization and low cost.

The invention relates to a power-system direct current power transmission line relay protection field and especially relates to a single-terminal electric-quantity whole-line quick action protection method which can be used to identify faults in and out of an HVDC transmission line area. An amplitude of a specific frequency component in a single-terminal direct-current filter branch is used to realize discrimination of the faults in and out of the area. The method of the invention is used to protect a single-terminal whole-line quick action in the direct current power transmission line of the power system. The protection can be achieved only by using the single-terminal electric quantity. The method has a low requirement to a sampling frequency. An algorithm is simple. Sensitivity is high. The method can be realized during engineering. The action speed is fast, selectivity is good and reliability is high. A theory is completed and is easy to be adjusted. The protection method of the invention can replace current traveling-wave protection which is taken as the main protection of the direct current power transmission line. And the method is especially suitable for realizing the whole-line quick action protection of the ultra/super HVDC power transmission line by using the single-terminal electric quantity.

The invention provides a system and method for detecting defects of micromotor rotor windings. According to the system and method, pulse square waves with specified peak values and frequencies are exerted to a tested rotor winding, response signals and standard rotor winding signals are collected, compared and analyzed, and whether the rotor winding has faults and fault modes are judged. The corresponding detection system comprises a pulse generator, a rotor winding, an integral circuit, an A/D switching circuit, a controller, a display terminal and a motor. The pulse generator exerts pulse signals on the rotor winding, and the integral circuit is connected to the two ends of each commutator bar of the rotor winding in parallel; the A/D switching circuit collects voltages at the two ends of an integrating capacitor C in the integral circuit and converts the voltages to digital signals which are transmitted to the controller; the motor is controlled by the controller to drive the rotor winding to rotate to the next set of commutator bars; the controller outputs an operation result to the display terminal. By means of the system and method, the states of the rotor winding can be automatically, quickly and accurately detected, a production line is optimized, and the yield of an assembly line is improved.

The invention discloses a method and a device for positioning a high-resistance grounding fault section of a power distribution network and a storage medium. The method comprises the following steps of acquiring zero-mode current recording data of fault fixed-section terminals; selecting zero-mode current initial wave heads according to the zero-mode current recording data, and aligning travelingwave heads of the zero-mode current recording data of the terminals; when the amplitude values of the zero-mode current initial wave heads are not smaller than a rated current value, according to thezero-mode current initial wave heads, calculating a product integral of sampling points of each terminal and the next terminal after breakdown, and determining a first grounding fault section according to a calculation result, thereby obtaining an initial wave head judgment result; performing cross wavelet transformation on the zero-mode current recording data acquired by each terminal and the next terminal, and determining a second grounding fault section according to a transformation result, thereby obtaining a cross wavelet phase judgment result; and when the initial wave head judgment result and the cross wavelet phase judgment result are consistent, obtaining a fault fixed-section result. The fault section can be accurately judged; and the method and the device have relatively high adaptability.

The invention relates to an elastic imaging method based on focused ultrasound vibration signals. An imaging system for usage comprises a signal generator, an ultrasonic pulse transceiver, a power amplifier, an excitation probe, a tracking probe, a data collecting card, a computer and a motion controller; through the excitation probe, ARF is generated in a focusing region and brings vibration of amedium of the focusing region, then secondary ultrasonic waves are emitted, amplitude value information of the secondary ultrasonic waves is detected, the elastic feature of the medium is estimated,the excitation probe is moved to scan a whole tested object field, and elastic distribution of the medium is reconstructed.

The invention discloses a method for detecting a multi-terminal DC(direct current) system fault based on transient high frequency energy, characterized by establishing an analytical expression of a fault component current of a multi-terminal DC system line; obtaining the transient high frequency energy of the current according to the analytical expression of the fault component current; and if thetransient high frequency energy of a line exceeds a preset protection threshold, determining that the line is a fault line. The invention has the following advantages: the threshold setting is easy to be realized, the robustness of the fault detection of the multi-terminal DC system is improved, the sampling frequency is low, and the transition resistance is good.

The invention discloses a method and device for locating a high-resistance ground fault section of a distribution network, and a storage medium. The method for locating the high-resistance ground fault section of the distribution network comprises the following steps: obtaining zero-sequence current and voltage recording data of each fault location terminal; calculating the average value of the absolute value of the ratio of the current integral value and the voltage difference value collected by each terminal according to the zero-sequence current and voltage recording data; calculating the average value ratio of each terminal and the subsequent terminal according to the average value, and determining the size of the average value ratio and a preset setting threshold; and recording the average value ratio and the terminal number when the average value ratio is greater than the setting threshold, and determining that the ground fault section is the section between the terminal corresponding to the number and the subsequent terminal according to the number, so that the section determination result is obtained. The invention has strong applicability, can be applied to different faultlocations and different transition resistances, can effectively improve the accuracy of determining the fault section, can effectively reduce the difficulty of fault location and reduce errors, and has low cost and a high engineering application value.

The invention discloses a direct power control method for current negative sequence component restraining under network unbalance. The direct power control method comprises the steps that three-phase voltage and three-phase current of a transformer are detected and transformed into a two-phase static coordinate system, T/4 delay positive-negative sequence decomposition is carried out on two-phase static voltage and two-phase static current, active power and reactive power of a system are calculated, and the active power and the reactive power are predicted; compensation power in the two-phase static coordinate system is calculated when negative-sequence current needs to be zero, the negative-sequence current is made to be zero, and given active power and reactive power of the system are calculated; a conditional function is set up, an SVPWM positive-sequence voltage component is solved, an SVPWM negative-sequence voltage vector is determined, and an SVPWM voltage vector is output to a PWM rectifier. The direct power control method has the advantages that during a network unbalance fault, it can be guaranteed that the system is stable, response speed is high, design of a power filter is facilitated, the requirement for system sampling frequency is not high, and high robustness and good adaptability are achieved.

The invention discloses a method for identifying excitation surge current and internal fault of a transformer, belongs to the technical field of power system relay protection, and is to solve the technical problem of identifying the excitation surge current and internal fault of the transformer in a power system. The method comprises the following steps: sampling current in a transformer differential circuit; carrying out absolute value taking and sorting operation and the like on a sampling data sequence, and calculating an equal square ratio R; if R is less than Rset, judging that the current current is an internal fault current, and starting differential protection; or otherwise, calculating a correction factor FC and a correction equal square ratio RC, and further identifying the current current according to whether RC is greater than Rset or not. The method for identifying the excitation surge current and the internal fault has the advantages of simple steps, small calculation amount, convenient engineering implementation and the like.

The invention discloses a satellite navigation signal channel SCB characteristic detecting method. The satellite navigation signal channel SCB characteristic detecting method comprises the following steps of: collecting a satellite navigation signal, and performing carrier wave stripping on the signal to obtain a baseband signal; performing lowpass filtering on the baseband signal; utilizing an ideal bandpass signal to calculate related curves; locking a point deviation curve according to the related curves; performing arithmetic averaging on the locked point deviation curve; and calculating SCB according to the mean result of the curve. According to the invention, the discreteness of single locked point deviation curve is considered, the cross-correlation disturbing influences of other signal components, data and the like are eliminated, and the navigation signal channel SCB characteristics can be assessed accurately.