418 results about "Harmonic analysis" patented technology

A method and system for assessing blood volume within a subject includes generating a cardiovascular waveform representing physiological characteristics of a subject and determining blood volume of the subject by analyzing the cardiovascular waveform. The step of analyzing includes generating a first trace of the per heart-beat maximums of the cardiovascular waveform, which is representative of the systolic pressure upon the cardiovascular signal, generating a second trace of the per heart-beat minimums of the cardiovascular waveform, which is representative of the diastolic pressure upon the cardiovascular signal, and comparing the respective first trace and the second trace to generate an estimate of relative blood volume within the subject. In accordance with an alternate method of analyzing harmonic analysis is applied to the cardiovascular waveform, extracting a frequency signal created by ventilation and applying the extracted frequency signal in determining blood volume of the subject.

A system for conducting performing real-time harmonics analysis of an electrical power distribution and transmission system is disclosed. The system includes a data acquisition component, a power analytics server and a client terminal. The data acquisition component is communicatively connected to a sensor configured to acquire real-time data output from the electrical system. The power analytics server is communicatively connected to the data acquisition component and is comprised of a virtual system modeling engine, an analytics engine and a machine learning engine. The machine learning engine is configured to store and process patterns observed from the real-time data output and the predicted data output, forecasting harmonic distortions in the electrical system subjected to a simulated contingency event.

The invention relates to a non-intruding type electric load real time decomposition method comprising off-line extracting electric characteristic parameter when consumer is working in stable state normally; choosing the main comsumer type based on practical situation of the load; on-line real time measuring voltage, current and power data of electric load port and performing harmonic analysis; weight synthetizing the choosed electric characteristic parameter of the electric load main comsumer type to approximatively estimate the actual measured current and power of the electric load; optimal solving the weight coefficient to find out the weight coefficient of each of main comsumer type and obtain the power consumption ratio of the electric load internal main consumer type for realizing load decomposition. The invention can not intrude into load interior, namely on-line obtaining power consumption ratio of the electric load internal main type consumer, the decomposition method can not only have higher precision and better stability, but also have quick computing speed to satisfy on-line real time decomposition request.

Systems, methods, and ultrasound transceivers equipped and configured to execute harmonic analysis and extract harmonic information related to a targeted organ of a subject are described. The methods utilize neural network algorithms to establish improved segmentation accuracy of the targeted organ or structures within a region-of-interest. The neural network algorithms, refined for detection of the bladder and to ascertain the presence or absence of a uterus, is optimally applied to better segment and thus confer the capability to optimize measurement of bladder geometry, area, and volumes.

The invention discloses a harmonic analysis method based on Kaiser self-convolution window dual-spectrum line interpolation FFT (Fast Fourier Transform) and a device thereof. The method comprises the following steps of sampling a signal: sampling a time-domain continuous signal, and discretizing to obtain an infinitely long discrete sequence; windowing a four-order Kaiser self-convolution window function: performing four-order Kaiser self-convolution window operation on the infinitely long discrete sequence; performing N-point FFT on a windowed and truncated signal to obtain the discrete spectrum of the signal; determining the peak parameter of the discrete spectrum: searching the local spectrum peak of each integer harmonic frequency around the integer harmonic frequency; and calculating a harmonic parameter: solving a coefficient alpha by adopting a discrete spectrum interpolation correction formula based on an LSM (Least Square Method), and calculating parameters such as a harmonic frequency, an amplitude, an initial phase angle and the like. Due to the adoption of the method, the fundamental and harmonic components of a tested signal can be detected rapidly and accurately, and accurate frequency measurement is realized; and the method is convenient for implementing an embedded system, and the tested signal can be detected continuously for a long time.

A utility for rapid development of three dimensional representations of electrical distribution switchgear is provided. These switchgear elevations have logical connections to the switchgear devices. An elevation can be modified to any dimensions with an infinite number of combinations and arrangements of meters and protection devices to quickly and accurately represent a customer's switchgear. Also, an event logger utility is provided for viewing, organizing and analyzing unusual behavior in a power system. The event logger utility passes a received message as an un-acknowledgeable or acknowledgeable alarm or as an event based upon the contents of a initialization file. A utility for the waveform capture is provided for viewing and analysis of waveforms (e.g., Fourier, frequency and / or harmonic analysis) captured by sophisticated metering devices. Waveforms from a device may be super-imposed for analysis. Processing of the collected waveform data to display any one of the eight waveform parameters (i.e., Ia, Ib, Ic, In, Va, Vb, Vc, Vx) or a combination thereof including an “all” selection in a window tiling format is provided.

There is provided an inspection method for inspecting an object built on a tire building drum to make up a pneumatic tire with respect to profile thereof in process of production of the tire includes, in which data with respect to a profile of the object for a single rotation of the tire building drum is acquired by a two-dimension laser sensor having a detection range along a lateral direction of the object while rotating the drum. Then, using the data so acquired, a radial run-out (RRO) in a circumferential direction of the tire is averaged out in a lateral direction of the object for harmonic analysis, and whether or not the magnitude of the harmonic obtained as a result of the analysis falls within a predetermined range is determined.

The invention provides a method for forecasting the tide level in a tidal river network and belongs to the technical field of hydrodynamic force simulation and hydrologic forecasting. A computational fluid dynamics (CFD) method and a water level forecasting method are comprehensively applied, the problem that the water level in the tidal river network is difficult to accurately forecast due to multi-branch stream bypass flowing and open sea tide influences is solved, and the application range and precision of tidal river network tide level forecasting are improved. The method mainly comprises the following steps that firstly, a tidal river network region and upstream riverway one-dimensional hydrodynamic force mathematical model is established; secondly, the hourly tide level processes of a control station of a river mouth are precast through harmonic analysis, and forecast values are corrected through measured data of the day before forecasting; thirdly, flow processes of control stations of an upstream are derived through a weighted moving average method; fourthly, tide level processes of all fracture surfaces in a tidal river network region are solved through the tidal river network region and upstream main stream area one-dimensional hydrodynamic force mathematical model, and the tide level forecasting of any fracture surface in the river network region is achieved.

The invention relates to a tide predicting method for the tide is influenced by various factors, including cyclical factors, such as tidal generation force, and non-cyclical factors, such as wind power, atmospheric pressure, coast characteristics, rainfall, dip angles of the lunar orbit and the like. The predicting accuracy of the traditional harmonic analysis method is influenced by partial tide number, and the traditional harmonic analysis method cannot analyze the influence of non-cyclical factors; the artificial neural network method developed recent years overcomes the defect that the non-cyclical factors cannot be predicted by the harmonic analysis method to a certain extent, but has great data volume required by study training samples and wide involve range, can cover various possible conditions, but has less station historical data of non-cyclical factors. The invention provides a predict model, wherein factors which influence tide non-cyclically, such as wind directions, rainfall, storm surge, coast characteristics and the like, can be fused into the model, and small sample data can receive more accurate results. In the method, a support vector machine (SVM)-based predict model is established, wherein, an SVM toolbox is imported into MATLAB 7.8; training sample data is trained by utilizing svmtrain function; the formed model is tested by using a test sample svmpredict function; and the trained and tested data can predict the tide in the same tide test station.

The invention discloses a high-precision harmonic analysis method improved on the basis of quasi-synchronous discrete Fourier transformation (DFT). The method comprises the step: changing the position of a frequency domain sample according to the drift of signal frequency when harmonic analysis is performed by applying the quasi-synchronous DFT, wherein the position of the frequency domain sample is mu2pi / N, and mu is the drift of the signal frequency, and mu is equal to 1 when the signal frequency does not have the drift. The harmonic analysis method disclosed by the invention comprises thinking: a variable barrier, i.e. the position of the frequency domain sample is changed according to the drift of the signal frequency when the harmonic analysis is performed. The technology disclosed by the invention is beneficial to more accurately obtaining the information, such as the amplitudes, the initial phase angles, the frequencies and the like of all harmonics in the fields of applying the harmonic analysis, such as the fields of power quality monitoring, electronic product production inspection, electric equipment monitoring and the like.

The invention discloses a control method for compensating location torque of permanent-magnet motor by injecting current harmonics; in the method, harmonic current is injected to interact with the fundamental wave permanent magnetic potential to generate an additional torque component, so that the additional torque can be equal to the amplitude of the fundamental wave and the ultra-harmonics component in the directional torque and the phase positions thereof are opposite and can be offset, thus achieving the aim of compensating the location torque. In the method, firstly harmonic analysis is carried out on the location torque of the permanent-magnet motor by using finite element simulation result or observed data and adopting the Fourier series approximation approaching method; secondly the aero load counter electromotive force of the permanent-magnet motor is analyzed and the corresponding mathematical expression is written out; and finally the injected harmonic current is worked out according to the principle that additional torque and location torque can offset each other.

The invention relates to a harmonic analysis technology of electric energy, in particular to a harmonic analysis method based on a windowed interpolation FFT (Fast Fourier Transform) base frequency tracking technology, belonging to the technical field of power electric energy quality analysis. The analysis method comprises the following steps of: a. acquirement of higher-precision base frequency: sampling by a low-frequency sampling rate electric energy signal; after adding a Hanning window to sampled data, carrying out FFT calculation; obtaining a higher-precision base frequency f by an interpolation method; and b. base frequency tracking and synchronous frequency doubling: sampling the electric energy signal again at the frequency of 128*f and carrying out FFT calculation on the sampled data to obtain amplitudes and phases of all harmonic waves. By adopting the technical scheme, compared with the prior art, the invention has the advantages of reducing the calculation complexity because a base frequency parameter is just calculated during windowed interpolation calculation and having higher precision of harmonic analysis results by realizing plesiochronous adoption by the base frequency tracking.

The invention relates to a method for measuring the signal frequency and harmonic parameters of an electric power system. The frequency, the amplitude and the phase of harmonics are acquired through modifying two maximum spectrum lines close to real frequency points in FFT data acquired by applying seven term Rife-Vincent (I) window to sampling data, wherein the seven term Rife-Vincent W(n)=sigma<k>(i=0)(-1)bicos(2pi / Nin), n=0, 1,.. N-1, wherein b0=1, b1=12 / 7, b2=15 / 14, b3=10 / 21, b4=1 / 7, b5=2 / 77 and b6=1 / 462. The method provided by the invention is simple to implement and can achieve very high precision in harmonic analysis applications of a digital substation, and the calculation is smaller than a general cosine window.

The invention discloses a harmonic characteristic analytical method of an MMC (Modular Multilevel Converter). The harmonic characteristic analytical method comprises utilizing operation conditions and system parameters of the MMC and considering a second harmonic component of the bridge arm current to calculate the bridge arm current of every bridge arm of the MMC; calculating the average capacitive current of sub-modules of the MMC through an average switching function model under the actual condition; calculating the average capacitive voltage of the sub-modules of the MMC according to the relationship between the voltage at two ends of a capacitor and the current which flows through the capacitor; calculating the total voltage of phase bridge arms of the MMC through the average switching function model under the actual condition; utilizing the fourier series harmonic analysis method and extracting second harmonics to perform analysis to calculate the double frequency circular current of the bridge arms. According to the harmonic characteristic analytical method of the MMC, a harmonic component of every electric parameter of the MMC can be calculated, so that the computation commonality is strong, the application range is wide, and the accuracy is greatly improved in comparison with the existing methods.

The invention discloses an operating method of a resistive current on-line monitoring system of a metal oxide arrester (MOA). Fundamental wave parameters of a resistive leakage current of the MOA are usually obtained according to a projection method. The method comprises the following steps of: sampling an electric network voltage and an MOA leakage current signal at the same time; acquiring a fundamental wave amplitude value and an initial phase angle of the electric network voltage by using a quasi-synchronization discrete Fourier transformation (DFT) harmonic analysis technology of a variable fence; acquiring the fundamental wave amplitude value and the initial phase angle of the MOA leakage current by using the quasi-synchronization DFT harmonic analysis technology of the variable fence; acquiring a projection angle of a fundamental wave of the leakage current on the fundamental wave of the electric network voltage according to the projection method; and acquiring the fundamental wave of the resistive leakage current of the MOA, and outputting and displaying the fundamental wave. By adoption of the operating method of the resistive current on-line monitoring system of the MOA, the analysis error of the quasi-synchronization DFT harmonic analysis technology is effectively avoided, and a high-accuracy harmonic analysis result is obtained, so that the reliability in test of the resistive current of the MOA based on a harmonic analysis theory is improved.

The invention relates to an axial circular runout and total runout single displacement error separation device and method, and belongs to the technical field of micro-nanometer ultra-precise measurement. In the method, an axial circular runout and total runout measurement device and an error separation system are organically integrated into a whole, a proper displacement angle alpha is selected in an error separation process, so that a workpiece performs a single small-angle displacement of a corresponding angle relative to a rotary main shaft, total harmonic separation of z(n) and g(n) in a harmonic range of between 1 and 100upr by measuring comprehensive errors A(n) and B(n) including a workpiece axial circular runout error g(n) and a main shaft rotary error z(n) before and after displacement of the workpiece, and utilizing fast Fourier series transform, harmonic analysis and other mathematic processing methods. According to the device and the system, when an existing error separation method is used for circular runout error separation, the defects that an error introduced by a rotary shaft cannot be completely separated, error separation time is long, various larger drifts are easily introduced and the like can be overcome, and the error separation device and the error separation process can be greatly simplified.

Methods are disclosed wherein the structural health of a civil structure, such as, but not limited to, a bridge or the like is measured by electronic distance measurement (EDM) from a plurality of stable locations to a plurality of cardinal points on the structure in a methodical manner. By measuring the coordinates of the cardinal points, the dynamic and long-term static behavior of the structure provide an indication of the health of the structure. Analysis includes: comparison to a Finite Element Model (FEM); comparison to historical data; and modeling based on linearity, hysteresis, symmetry, creep, damping coefficient, and harmonic analysis.

An inspection method for inspecting beads provided on a tire building drum in process of production a pneumatic tire includes measuring a displacement amount in a radial direction on each of the beads lying axially on both sides of the drum with a distance sensor such as an eddy current sensor while rotating the drum, synthesizing displacement amounts so obtained on the beads on both the sides, calculating a harmonic of the displacement amounts in the radial direction of the beads by performing harmonic analysis on a resultant synthesized displacement amount, and determining whether the magnitude of the harmonic so calculated falls within a predetermined range.

The invention discloses a harmonic modal analysis method for an offshore wind farm. The method comprises the steps of 1) building a system harmonic model according to an offshore wind farm system, namely a connection relationship between each component and a cable; 2) establishing a network admittance matrix of the system according to the system harmonic model, solving a modal impedance frequency spectrum of the system by utilizing a modal method, calculating a participation factor of each node, and determining a real occurrence position of harmonic vibration; 3) assessing the sensitivity of electric parameters of components of the system; and 4) assessing the sensitivity of design parameters of the system. According to the method, an equivalent model is built according to the parameter of each component of the wind farm, the harmonic performance of the system under different topological parameters, cable parameters, transformer parameters and other parameters is studied by applying the modal analysis method, and the topological design and component model selection of the wind farm can be optimized.

The invention discloses a frequency domain interpolation electric power harmonic wave analysis method based on discrete Fourier transform. The method comprises the following steps: (1) conducting time domain continuous signal discretization; (2) selecting an appropriate cosine-class window to weight a discrete sampling sequence according to measuring requirements; (3) performing fast Fourier transform on the sequence; (4) finding the two longest spectral lines close to harmonic waves in the form of spectrum peak searching, and calculating a spectrum value ratio between the two lines; (5) obtaining a frequency deviation according to a Newton interpolation method; and (6) further solving the amplitude, frequency and initial phase of sub-harmonic waves on the basis of the obtained frequency deviation. A fast interpolation based on table look-up is independent of a window function. The method is universally applied, and can be combined with any window function to conduct harmonic wave analysis. Meanwhile, no complex operation exits, the computational complexity is low, and the method is easy to realize in an embedded system.

The invention discloses a real-time monitoring and estimating system of power quality based on CAN bus for electric system and each class of power distribution system, which comprises the following network structures: data gathering layer as the first layer, which groups multiple stations to manage and transmits all the electric power network signal into standard voltage to the data gathering card; data disposing layer as the second layer, which converses the electric parameter by data gathering layer to realize the calculation and analysis of electric quality such as voltage fluctuation, harmonic analysis, flicker and so on; data transmitting layer as the third layer, which utilizes CAN bus to establish high-reliability opened data communicating circuit and realizes the conversion of order and data between middle control chamber PC set and working control machine; user layer as the fourth layer, which builds friend operational interface to provide display, storage, analysis and estimation function of the monitored data and makes the user to observe real-time data of wind electric-field operation directly.

The invention discloses a harmonic analysis method based on the Kaiser window function double-spectral-line interpolation FFT. The method is suitable for analysis and monitoring on voltages, currents and harmonic waves of a power network. The method comprises the steps of firstly, using linear frequency modulation Z conversion for extracting fundamental wave signal parameters (amplitudes, frequencies and phase positions) from electric power signals containing the harmonic waves in a high-precision mode, then adding a Kaiser window function into the analyzed electric power signals to cut off the electric power signals, using the FFT for calculating frequency spectra of remaining signals, and precisely calculating parameters of the electric power harmonic waves according to interpolations of the Kaiser window function by the harmonic frequencies in a frequency domain. The method can effectively overcome fluctuations of fundamental frequencies, and influences of white noise on the harmonic analysis, under the non-integer cycle cut-off condition, the relative error of the frequency calculation of the 21-time harmonic signals is 1.4*10%, the relative error of the amplitude calculation is smaller than or equal to 0.002%, and the relative error of the initial phase position calculation is smaller than or equal to 0.0001%.

Provided are methods and apparatus for characterizing a power waveform. Some such methods include sampling the power waveform to generate a plurality of samples and, for each of the samples, recursively processing the sample to generate an aggregate signal energy value, processing the sample to generate a harmonic component signal energy value associated with at least one target harmonic frequency, and accumulating the aggregate signal energy value and the component signal energy value with previously generated aggregate signal energy values and component signal energy values to generate an accumulated aggregate signal energy value and an accumulated harmonic component signal energy value. Methods also include characterizing the power waveform responsive to the accumulated aggregate signal energy value and the accumulated harmonic component signal energy value.

The invention relates to a harmonic analysis method based on asynchronous sampling, belonging to the field of signal harmonic detection technique. The method comprises the steps as follows: 1) a plurality of prearranged weight coefficients corresponding to signal frequencies one-to-one are sequentially memorized in a memory; 2) the harmonics are sampled under a constant sampling period; a sampling signal is output to a digital signal processor after A / D conversion; 3) the digital signal processor processes digital signals which are converted by multi-path A / D converters, and according to the frequencies, the positions of the weight coefficients needed to be invoked in the memory are determined; 4) in the digital signal processor, corresponding weight coefficients invoked in the memory is multiplied by the input digital signals, subsequently, FFT processing is carried out; and 5) the FFT-processed result is displayed or printed. The method overcomes the synchronous difference problem of the harmonic analysis, obtains real-time harmonic analysis signals with high precision, and can be applied to the signals in the fields such as machines, power, information, geology, hydrology and the like so as to carry out the harmonic analysis.

The invention discloses a fault arc detection method. The method comprises the following steps that current signals are collected and subjected to harmonic analysis, the higher harmonic ratio is calculated, the higher harmonic ratio in a current time period is obtained by collecting signals within the time period set before and after switch-on and switch-off of a circuit, and then a time-related mathematical model of the higher harmonic ratio of the circuit is obtained; the change of the higher harmonic ratio of the circuit at the moment of being switched off is calculated and compared with the actual change of the higher harmonic ratio of the circuit; if the frequency that the actual higher harmonic ratio is higher than a theoretical higher harmonic ratio is larger than a threshold value, it is regarded that a fault arc happens. The fault arc detection method has the advantages that a unique model for the circuit is obtained by analyzing the circuit, and analysis in advance is not needed.

The invention belongs to the technical field of micro-grid signal processing, and relates to a micro-grid harmonic and inter-harmonic analysis method based on cubic spline interpolation waveform reconstruction. The method comprises the following steps of: sampling the original measuring signal at a given sampling frequency to acquire the original sampled signal; analyzing the original sampled signal to determine the actual fundamental frequency of a system by using a Hanning windowed double interpolation fast Fourier transform (FFT) algorithm; obtaining the corrected sampling frequency according to the actual fundamental frequency of the system; reconstructing a sampling waveform by using a cubic spline interpolation algorithm; processing the reconstructed signal sequence to determine fundamental waves and all harmonic components by using the Hanning windowed double interpolation FFT algorithm; subtracting the solved fundamental waves and each harmonic component from the original sampled signal; and determining each inter-harmonic component by using the Hanning windowed double interpolation FFT algorithm. By the method, spectrum leakage and a picket fence effect which are generated during harmonic analysis can be effectively reduced, and micro-grid harmonic and inter-harmonic analysis accuracy is improved.

A method for separating roundness error of single transposition includes selecting proper transposition angle a for carrying out single small angle transposition in relevant angle to rotation major axis and realizing complete harmonic separation of z(n) and g(n) as in scope of 1-100 upr harmonic wave by measuring workpiece error g(n) and major axis transposition error z(n) before and after workpiece transposition as well as utilizing quick. Fourier series transform and harmonic analysis.

The invention discloses a cascade inverter H-bridge unit short circuit fault detecting method based on harmonic analysis of switching frequency, which is suitable for a carrier phase-shifting PWM (pulse width modulation) manner based on the harmonic analysis to output phase voltage and comprises three parts, namely output alternating voltage sampling, extracting and processing of harmonic wave close to the switching frequency, and fault judging and fault locating. Three-phase output voltage of a cascade inverter is respectively subjected to low-pass filtering and A / D (analog-to-digital conversion) sampling, and is subjected to discrete Fourier transformation to obtain characteristic harmonic; a comparison result of the characteristic harmonic amplitude and a fault threshold is utilized as the evidence of fault judging, wherein the fault threshold is obtained by carrying out a series of calculation on command voltage. The fault locating is determined through a phase angle range of the harmonic of the switching frequency. According to the cascade inverter H-bridge unit short circuit fault detecting method based on the harmonic analysis of the switching frequency, which is disclosed by the invention, the three-phase output voltage of the inverter is collected, and no other hardware circuit is additionally arranged, so that the cost is reduced, and the efficiency is improved; the application capability is strong, and the application value in the study on the real time fault detection of the cascade inverter exists.