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

Co-channel full-duplex system based on MPPSK modulation

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.
Owner:苏州东奇信息科技股份有限公司

Single-ended electrical quantity full-line quick-action protection method for recognizing faults inside and outside high-voltage direct-current transmission line region

The invention relates to the field of relay protection of direct-current transmission lines of power systems, in particular to a single-ended electrical quantity full-time quick-action protection method for recognizing faults inside and outside a high-voltage direct-current transmission line region. The faults inside and outside the high-voltage direct-current transmission line region are recognized by using an amplitude of a special frequency component of electrical quantity of the direct-current line side of a single-ended convertor station. The invention is mainly used in single-ended electrical quantity full-line quick-action protection of the direct-current transmission line in the power system, only needs to adopt the singe-ended electrical quantity, has low requirement on the sampling frequency and a simple algorithm, is easy to realize on the engineering, has the advantages of high action speed, good selectivity and high reliability, and is complete in theory and easy to integrate. The protection method in the invention can be used as the main protection of the direct-current transmission line instead of the traditional traveling wave protection, and is especially suitable for full-line quick-action protection of extra / super high-voltage direct-current transmission lines by using single-ended electrical quantity.
Owner:XI AN JIAOTONG UNIV

Non-intrusive resident load identification method based on S_Kohonen

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.
Owner:NORTH CHINA ELECTRIC POWER UNIV (BAODING)

Finite state set asynchronous motor model prediction flux linkage control method and device

The invention discloses a finite state set asynchronous motor model prediction flux linkage control method. The method includes the steps that a torque instruction is obtained through a speed external loop PI adjustor, and a flux linkage amplitude instruction is set to be at a rated value; an equivalent stator flux linkage vector instruction is obtained; duty ratios corresponding to three voltage vectors are calculated; a stator flux linkage vector instruction at the next moment is predicted; the three voltage vectors making the target function value be minimum and the corresponding duty ratios are selected to serve as the optimal output information of a prediction controller; according to the optimal output information of the prediction controller, driving signals of all switch tubes of an inverter are constructed. The invention discloses a finite state set asynchronous motor model prediction flux linkage control device. According to the finite state set asynchronous motor model prediction flux linkage control method and device, the problems that according to a traditional model prediction control scheme, complicated weight coefficient debugging is needed, steady state torque and current ripples are large, the requirement for sampling frequency is high, and switching frequency is not fixed are solved.
Owner:NORTH CHINA UNIVERSITY OF TECHNOLOGY

Image sensor for pixel splitting and merging and signal transmission method of image sensor

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.
Owner:SHANGHAI INTEGRATED CIRCUIT RES & DEV CENT

Frequency modulation wave marking method for time-difference process ultrasonic flowmeter

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.
Owner:ZHEJIANG SCI-TECH UNIV

Online monitoring method for degradation of insulated gate bipolar transistor

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.
Owner:ZHEJIANG UNIV +1

Distribution network fault line selection method based on extensional fusion of pattern spectrum analysis and morphological peak and valley detection

ActiveCN103954884AImprove anti-interference abilityNot affected by the size of the transition resistanceFault locationElectric power systemExtension theory
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.
Owner:KUNMING UNIV OF SCI & TECH

Islanding detection method based on voltage harmonic fault component

The invention discloses an islanding detection method based on voltage harmonic fault component. Through detecting differences presented by voltage signals at specific frequencies of 150 Hz, 250 Hz and 350 Hz in the case of normal grid-connected operation and islanding operation, the islanding operation state is detected. A sliding data window is used for calculating absolute values |DeltaU3|, |DeltaU5|, and |DeltaU7| for voltage specific subharmonic fault components at the grid-connected inverter end, and whether islanding happens according to the sizes of the |DeltaU3|, the |DeltaU5|, and the |DeltaU7|. The quality of electric energy outputted by the grid-connected inverter is not influenced, the transient response of the system is not disturbed, the sampling frequency is lowly required, and hardware realization is facilitated. The method of the invention can quickly and effectively detect islanding effects in the most serious islanding condition defined by the IEEE Std.1547.1 standard, is applicable to various broken circuit conditions, and has good practicality.
Owner:XIAN UNIV OF SCI & TECH

Multiple-channel radio-frequency signal adaptation system

The invention discloses a multiple-channel radio-frequency signal adaptation system in the technical field of digital signal processing, and the system comprises an automatic gain control module, a direct frequency conversion module, a digital-analog conversion module, a clock control module and a digital signal processor, wherein the digital signal processor is composed of a branching unit, N paiallel and independent control signal processing branches and a combiner. The system provided by the invention has the advantages of simple structure, and good phase noise index; and the precision of the radio-frequency delay is set to 0.025 microseconds, the range of the radio-frequency delay is set to second level, multiple channels can work independently, and any channel can be set to independently open and close.
Owner:ANYWAVE COMM TECH

Fault line selection method for resonant grounded power distribution system by pattern spectrum

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.
Owner:KUNMING UNIV OF SCI & TECH

Hierarchical location method for locating fault of active power distribution network by utilizing multi-source data

The invention provides a hierarchical location method for locating the fault of an active power distribution network by utilizing multi-source data. The method comprises two levels of initial region layer positioning and accurate line layer positioning. According to the method, firstly, the information of a circuit breaker, a section switch and an interconnection switch monitoring terminal FTU, which is uploaded at a fault moment, is comprehensively utilized. The information is subjected to fault section area layer positioning, and then a line layer is positioned in the determined range of a fault section. The calculation is carried out by utilizing the electric quantity information of nodes at the two ends of the fault section and then an accurate fault position is obtained. The result ofthe verification shows that, the method is not influenced by the fault type and the position, and the fault positioning is rapidly realized. The adopted fault positioning principle is simple and reliable. The method is strong in anti-transition resistance capability and the sampling frequency requirement of the method is not high. Meanwhile, the fault positioning precision can be improved by increasing the sampling frequency, so that the method has higher practical application value.
Owner:JIANGSU ELECTRIC POWER CO +2

Asynchronous motor model type predict flux linkage control method and device

The invention discloses an asynchronous motor model type predict flux linkage control method. The asynchronous motor model type predict flux linkage control method includes: according to a mathematical model of a motor, generating the stator flux linkage vector reference value; according to the acquired stator flux linkage vector reference value, calculating the reference voltage vectors; adopting a space vector pulse width modulation method to calculate two nonzero vectors and one zero vector required for synthesizing the reference voltage vectors and action time of the reference voltage vectors; according to size relationship of the action time is summed in pairs, acquiring two sections of basic voltage vectors and action time thereof in one control period. By the arrangement, a stator flux linkage vector is taken as a control target, simpleness and practicability in calculation are achieved, and complicated weight coefficient design and adjust problem in a traditional control scheme is effectively solved; the two voltage vectors are generated, so that control effect is obviously improved by reducing steady-state torque ripple and current harmonics of a motor, and meanwhile, requirements on sampling frequency is lowered.
Owner:NORTH CHINA UNIVERSITY OF TECHNOLOGY

HVDC power-transmission whole-line speed protection method by using direct-current filter current

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.
Owner:XI AN JIAOTONG UNIV

System and method for detecting defects of micromotor rotor windings

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.
Owner:CHONGQING INST OF GREEN & INTELLIGENT TECH CHINESE ACADEMY OF SCI

Elastic characteristic detecting method based on focused ultrasonic acoustic vibration signal

The invention relates to an elastic characteristic detecting method based on a focused ultrasonic acoustic vibration signal. An adopted detecting system comprises a signal generator, an ultrasonic pulse transceiver, a power amplifier, a stimulation probe, a tracking probe, an N1 collecting card and a computer. By stimulating the stimulation probe, ARF is generated on a focusing area, vibration ofa focusing area medium is caused, then secondary ultrasonic waves are emitted, amplitude information of the secondary ultrasonic waves is detected, and the elastic characteristic of a medium is evaluated.
Owner:TIANJIN UNIV

Method and device for positioning high-resistance grounding fault section of power distribution network and storage medium

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.
Owner:ELECTRIC POWER RESEARCH INSTITUTE, CHINA SOUTHERN POWER GRID CO LTD +1

Elastic imaging method based on focused ultrasound vibration signals

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.
Owner:TIANJIN UNIV

Longitudinal connecting protection method for identifying inner and outer faults of hybrid double-end DC power transmission line area

The invention discloses a longitudinal connecting protection method for identifying inner and outer faults of a hybrid double-end DC power transmission line area. The method comprises the steps of ina converter station, acquiring a current magnitude signal from a current sensor at a local-pole DC power transmission line side; calculating a current fault component according to the local-pole current; calculating summation of the current fault components in a selected fault data window length, and when the summation is higher than a starting threshold value, performing starting protection; whenthe current fault component is same with a reference direction, determining the phase to 0 DEG; and when the current fault component is opposite from the reference direction, determining the phase to-180 DEG C. When the fault occurs in the DC line, the phases of the current fault components of the converter stations at two sides are same. When the fault occurs outside an area, the phases of thecurrent fault components of the converter stations at two sides are opposite. According to a fact that the phases of the current fault components at a rectification side and an inversion side are same, determining for the in-area fault and the outer-area fault of the hybrid double-end DC power transmission line area can be performed. The method according to the invention has advantages of low requirement for sampling frequency of the protecting device, easy realization, high reliability and high transition resistance.
Owner:菏泽心爱车业有限公司

Method for detecting multi-terminal DC system fault based on transient high frequency energy

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.
Owner:SHANGHAI MUNICIPAL ELECTRIC POWER CO +2

Electrical appliance operating state recognition method based on dual-sliding window

InactiveCN105607475ASolving the Steady State Discriminant ProblemSolve the problem of operating status identificationAdaptive controlElectricityElectric power system
The present invention discloses an electrical appliance operating state recognition method based on a dual-sliding window. The method comprises the steps of inputing a user electricity consumption overall load, identifying a steady-state load, detecting steady-state load change, correcting the steady-state load, identifying an electrical appliance operating state, and outputing electrical appliance operating operation sequence. According to the method, in the condition of known user total power consumption and electrical appliance power consumption information, the use condition information of a user electrical appliance is analyzed, the method has an important reference value for the power system data publication and has an important reference meaning for understanding the use condition of the electrical appliance and rationally using electrical energy by the user.
Owner:XI AN JIAOTONG UNIV

Current transformer saturation identifying method and device

The invention provides a current transformer saturation identifying method and device. According to the method, a peak point before a zero crossing point, the zero crossing point and a peak point after crossing point in sampling data are determined, data between the peak point before the zero crossing point and the zero crossing point and data between the peak point after the zero crossing point and the zero crossing point are subjected to normalization processing respectively, then a deviation value through a data sequence obtained after combined data processing, and if the deviation value is larger than zero, it is judged that a current transformer is saturated. Since whether the deviation value is larger than zero or not depends on the overall distribution characteristics of the sampling data, the current signal of the current transformer can be distorted when the current transformer is saturated, and the deviation value obtained by means of the distribution characteristics of the data obtained after the current signal distortion can be larger than zero so that it can be accurately judged that the current transformer is distorted. The method has the advantages of that the capacity of resisting disturbance is high, the method is little affected by noise, the requirement for the sampling frequency is low, the calculation is simple, the requirement for the operational capability of a protective device is low, and on-line real-time monitoring is easily achieved.
Owner:STATE GRID CORP OF CHINA +2

Power distribution network fault intelligent searching and positioning method based on multi-source data fusion

InactiveCN110687398AAccurate fault locationThe principle of fault location is simple and reliableFault location by conductor typesMulti source dataFault occurrence
The invention discloses a power distribution network fault intelligent searching and positioning method based on multi-source data fusion, and relates to the field of the power distribution network fault diagnosis. The method comprises the following steps: determining a fault occurrence high-probability region, establishing a fault data matrix related to the fault occurrence high-probability region and a network topological node according to the multi-source data of the power distribution network for fault region positioning; constructing a fault description matrix by utilizing the uploaded information of monitoring terminals of a circuit breaker, a section switch and an interconnection switch at the fault moment by the fault data matrix, then performing fault region layer positioning; performing line layer positioning in the determined fault section range, and calculating by utilizing electric quantity information of the nodes at two ends of the fault section, thereby obtaining the precise fault location. Under the support of a judgment result of the region layer, the precise positioning of the fault can be quickly realized, the adopted fault positioning principle is simple and reliable, and the strong anti-transition resistance capacity is provided; a sampling frequency requirement is low, and the fault positioning precision can be improved by improving the sampling frequency.
Owner:ELECTRIC POWER RES INST OF GUANGXI POWER GRID CO LTD

Insulator pollution flashover leakage current signal sparse representation method based on wavelet analysis

InactiveCN103558498AAchieve sparse representationImprove acquisitionElectrical testingSignal qualityElectric power system
The invention discloses an insulator pollution flashover leakage current signal sparse representation method based on wavelet analysis in the technical field of electric power system signal processing. The method comprises the steps that a sym8 orthogonal wavelet basis is adopted as a sparse basis psi, a wavelet sparse transformation orthogonal matrix is constructed, and the sparseness K of original leakage current signals is determined; a Gaussian random matrix fai is constructed and used as a measurement matrix, a measurement value M is calculated according to the sparseness K, and a measurement vector y and a sensing matrix theta are obtained through a sparse representation equation; the original leakage current signals are reconstructed through the measurement vector y and the sensing matrix theta under an OMP algorithm. According to the method, the requirement for sensor sampling frequency is lowered, the sampling and reconstruction speed of the signals is improved on the premise of not influencing signal quality, and meanwhile reconstruction accuracy is guaranteed.
Owner:NORTH CHINA ELECTRIC POWER UNIV (BAODING)

Method and device for locating high-resistance ground fault section of distribution network, and storage medium

InactiveCN110542832AImprove accuracySolve the problem of weak ability to withstand transition resistanceFault location by conductor typesInformation technology support systemHigh resistanceEngineering
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.
Owner:ELECTRIC POWER RESEARCH INSTITUTE, CHINA SOUTHERN POWER GRID CO LTD +1

Identification method for excitation surge current of transformer based on kurtosis and skewness

The invention discloses an identification method for excitation surge current of a transformer based on kurtosis and skewness. The identification method comprises the following steps: initially setting a first setting value, a second setting value and a third setting value, performing uniform continuous sampling on differential current of the transformer by adopting an assigned sampling frequency to obtain a sampling value sequence; if a current effective value of the differential current is smaller than the first setting value, exiting the procedure, and otherwise, aiming at the current sampling value sequence, calculating the kurtosis and the skewness of the differential current of the latest power frequency cycle; if the kurtosis is greater than the second setting value and the skewness is greater than the third setting value, judging that the transformer is in an operation state of the excitation surge current, and locking differential protection of the transformer, otherwise, judging that the transformer is in other non-excitation surge current operation states; returning to continuously process the current effective value of the differential current. The identification method disclosed by the invention has the advantages of obvious criterion distinguishing degree, high correctness of identification result, low requirement on hardware realization, short judgment time, good real-time property and low requirement on hardware of an implementation device.
Owner:STATE GRID CORP OF CHINA +2

Direct power control method for current negative sequence component restraining under network unbalance

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.
Owner:湖南中聚福能源科技有限公司

Method for identifying excitation surge current and internal fault of transformer

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.
Owner:HENAN POLYTECHNIC UNIV

Satellite navigation signal channel SCB characteristic detecting method

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.
Owner:XIAN INSTITUE OF SPACE RADIO TECH

Energy detection device for photoetching machine

The invention discloses an energy detection device for a photoetching machine, which is characterized by comprising a reflector, an integral rod, a detector, a detector signal processing circuit, a signal acquisition card and a computer sequentially along the light advancing direction, wherein the integral rod is located on the focal plane of the reflector; the output end of the detector is connected with a current signal input end of the detector signal processing circuit; and the output end of the detector signal processing circuit is connected with the input end of the computer via the signal acquisition card. The reflector is adopted to bend a light path, thereby reducing the entire height of the photoetching machine; the detector signal processing circuit can perform amplification, integration and keeping on narrow pulse signals, thereby reducing demands of a subsequent signal acquisition circuit and effectively eliminating influences of aperture jitter on a measurement result during the signal acquisition process; and synchronous signals of an integral keeping circuit do not need to be inputted from outside the energy detection device, thereby effectively isolating outer noise signals and improving the anti-interference ability of the energy detection device.
Owner:BEIJING GUOWANG OPTICAL TECH CO LTD
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