77 results about "Harmonic model" patented technology

A 2.3 kb/s speech coding technique with harmonic excitation and linear prediction is disclosed. The speech signals are acquired by speech acquisition system and then inputted to the processor of computer. The fundational tone detecting method and voiced sound analysis method are used to split the LPC exciting signal into lower band associated with voised sound and higher band relative to voiceless sound. A united harmonic model with a fixed phase spectrum of voiced sound of man speech is used to express the harmonic component and pseudo-noise component. An interpolation method is used to reduce noise. A short-lag filter is used for high quality of synthetic speech.

An engine sound synthesis system is operable to analyze sound. Operation of the system may include providing an input sound signal to be analysed and determining a fundamental frequency of the input signal from the input signal or from at least one guide signal. Furthermore, the frequencies of higher harmonics of the fundamental frequency are determined, thus determining harmonic model parameters. A harmonic signal based on the harmonic model parameters is synthesized and a residual signal is estimated by subtracting the harmonic signal from the input signal. Residual model parameters are estimated based on the residual signal. Furthermore, a corresponding method for synthesizing a sound signal is described.

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 modeling method for a harmonic model of a three-phase charger of an electric vehicle. The modeling method comprises the following steps: deducing a time-domain expression of an alternating current of the charger of the electric vehicle according to a three-phase uncontrollable bridge type rectification equivalent circuit; creating a three-phase charger harmonic coupling admittance matrix according to obtained charging currents in two work modes; combining the time-domain alternating current with a voltage of the charger, and proposing a model parameter determination method, wherein a coupling effect of the charger-terminal voltage and a harmonic current is considered in the model and matrix elements are not changed along with a harmonic voltage of the charger; creating the harmonic model of the three-phase charger of the electric vehicle in combination with the created coupling admittance matrix according to an admittance matrix parameter calculation method, wherein the harmonic model is used for providing a good theoretical basis for analyzing the characteristics that the harmonic current of a charging station with a plurality of chargers is changed along with the number of the chargers and the charging power. The modeling method can be used for directly and effectively calculating the harmonic current of the three-phase charger of the electric vehicle.

The invention belongs to the technical field of signal processing, and relates to a speech enhancement method based on speech presence probability and phase estimation. The method comprises the following steps: (1) estimating the speech presence probability; (2) estimating the pure voiced phase; (3) estimating the pure speech magnitude spectrum; and (4) estimating pure speech signals. The Q value is estimated through a multivariable linear regression technology, and the accuracy of speech presence probability estimation is improved. The pure voiced phase is estimated between adjacent bands using a harmonic model of short-time Fourier transform domain. The pure speech magnitude spectrum is estimated based on the phase difference, and the compensation effect of phase on the pure speech magnitude spectrum is fully utilized. The speech enhancement method of the method is a single-channel speech enhancement method. Speech signals with noise are collected using one microphone. The method is easy to implement. The problem that estimation of speech presence probability is inaccurate can be well solved. The compensation effect of the voiced phase and the phase difference on the pure speech magnitude spectrum is fully utilized. Thus, the performance of the speech enhancement method is improved.

Voiced speech preprocessing employs waveform interpolation or a harmonic model circuit to smooth a transition region and simplify speech coding. At low bit rates, the speech is coded by a system that maintains a high perceptual quality in the transition region from a voiced (quasi-periodic) portion of the speech signal to an unvoiced (non-periodic) portion of the speech signal. Similarly, the transition region from an unvoiced portion to a voiced portion is conditioned to maintain a high perceptual quality at a low bandwidth. The transition region from one type of voiced region to another type of voiced region is also smoothed. The transition region is smoothed to create a quasi-periodic speech signal.

The invention discloses a harmonic analysis algorithm combining fast Fourier transform (FFT) and nonlinear least square. The harmonic analysis algorithm is applied in the field of harmonic analysis of power grids, and can realize accurate calculation of frequency, amplitude and phase of power grid signals. The technical scheme (1) provides a method for calculating initial parameters of harmonic by using FFT and establishing a harmonic model, and (2) provides a nonlinear least square method for solving the parameters of the harmonic model. The algorithm has the advantages that influence of data length in no-parameter harmonic analysis on resolution is avoided, and the frequency resolution is improved; the structure and the initial parameters of the model are provided by the FFT, the parameter modeling problem of the least square is solved, and the initial values of the parameters are provided; by proper initial value selection, the initial value sensitivity of the iterative algorithm is reduced, and the iteration step is greatly reduced, so that the calculation efficiency is improved; and the parameter calculation precision of the nonlinear least square algorithm is further higher than that of a Hanning window interpolation method.

The invention provides a wind farm harmonic evaluation prediction method. The method includes the following steps that: a mathematical model is established for individual wind turbine generator sets in a wind farm to be established, and the overall distribution condition of harmonic current of various orders which is outputted by the individual wind turbine generator sets under historical wind speed at a corresponding region can be obtained through utilizing the mathematical model, and a corresponding probability density function can be obtained through utilizing the least square fit; the historical data of harmonic current of an existing wind farm are put into statists, so that the overall distribution interval of harmonic phases of various orders or the discrete degree of the harmonic phases of various orders can be obtained, and therefore, a random model of the phases is established; and the amplitude and phase conditions of the harmonic current of the sets in the wind farm can be simulated according to the random model; amplitude and phase variation values of harmonic current brought by power transmission lines and transformers thereof are calculated according to a wind farm topologic structure diagram and a power transmission line and transformer harmonic model, so that the magnitude and phase angle of the harmonic current of various orders brought by the sets can be obtained, wherein the harmonic current is harmonic current which has not been aggregated to a main transformer; and harmonic phase superposition based on sector distribution is evaluated.

The invention discloses a harmonic instability analysis method for a double-fed fan grid-side converter, comprising the following steps: firstly, building a harmonic model for the double-fed fan grid-side converter; secondly, only considering influence of a current control loop and grid-side impedance, and building an output admittance small signal model under a d axis according to the model in the step 1; thirdly, building a return ratio matrix under the influence of the d axis according to the model in the step 2; fourthly, obtaining an output impedance closed loop transfer function under adq axis and a return ratio matrix thereof according to the model in the step 2; and fifthly, respectively extracting characteristic values of the return ratio matrixes obtained in the step 3 and the step 4, and carrying out harmonic instability analysis on each parameter according to a generalized Nyquist criterion. The method disclosed by the invention can simply and visually judge and control influence of parameters as well as conversion trends of inductances and resistances at a grid side and an alternating current side on system stability.

The invention discloses a VSC harmonic modeling method based on a PWM modulation principle. A harmonic model of a VSC type converter is established by adopting a time domain analysis method; the method starts from the basic concept of a pulse width modulation (PWM) technology, a commutation process of a thyristor is ignored, by establishing two time variables of a carrier phase and a modulation wave phase, a universal VSC type converter alternating current side harmonic voltage analytical expression is obtained through Fourier decomposition, a Fourier coefficient of the general VSC type converter alternating current side harmonic voltage analytical expression is further simplified through a double accumulation table expression, so that a, b and c phases of bridge arm voltages, line-line voltages and alternating current side phase voltages are obtained. Only three input data of the direct current voltage, the modulation ratio and the carrier frequency are used for solving the content ofeach harmonic of the alternating current side, and the VSC type converter is approximately regarded as a harmonic voltage source.

The invention belongs to the ground nuclear magnetic resonance data processing field and discloses a method for eliminating an adjacent-frequency harmonic in ground nuclear magnetic resonance data. The method comprises the following steps of inputting ground nuclear magnetic resonance measurement data, measuring an experimental-location ground magnetic field and calculating a Larmor frequency; searching a power frequency harmonic fundamental frequency, modeling a power frequency harmonic and calculating and acquiring all harmonic coefficients; and determining whether there is an adjacent frequency harmonic according to a frequency difference between a Larmor frequency and each harmonic frequency, if there is no adjacent frequency harmonic, using the harmonic fundamental frequency and the harmonic coefficients to calculate and acquire a harmonic model, and subtracting the harmonic model from measured data, and if there is the adjacent frequency harmonic, removing the power frequency harmonic outside an adjacent domain harmonic and then removing the adjacent domain harmonic based on a fitting method. In the invention, under the condition that a nuclear magnetic resonance signal is not lost, the influence of the adjacent-frequency harmonic in the power frequency harmonic on subsequent data processing and inversion is removed. Especially when the Larmor frequency of the experimental location is close to the high order harmonic of the power frequency harmonic, a ground nuclear magnetic resonance signal characteristic can be accurately extracted and inversion result accuracy is increased.

The invention provides a calculation method for high-frequency harmonic power flow of an active power distribution network, aiming at the problems of how to calculate the high-frequency harmonic power flow of the active power distribution network, and no related calculation methods in the prior art. The calculation method comprises the steps of 1) obtaining a high-frequency harmonic impedance model of each component; 2) performing equivalence on high-frequency background harmonics and voltage source and current source type grid-connected inverters; 3) calculating harmonic voltages of to-be-calculated nodes of the active power distribution network during separate action after equivalence; and 4) obtaining the high-frequency harmonic power flow of the to-be-calculated nodes by utilizing a superposition theorem. According to the method, the high-frequency harmonic power flow of the active power distribution network is obtained by utilizing an equivalent high-frequency harmonic model of the active power distribution network and the superposition theorem in electrotechnics, so that high-frequency harmonic power flow distribution can be mastered more accurately and harmonic control measures can be better established for reducing harmonic control cost and influence on a power system; and therefore, the method has a very important effect for research and development of the active power distribution network.

The invention discloses a method and system for extending orders of spherical cap harmonic models of earth disturbance gravity fields. The method comprises the following steps of: in an aircraft launching process, determining a spherical cap radius by taking a launching first area as a to-be-approached spherical cap area; determining a spherical cap boundary condition according to the spherical cap radius; and according to the spherical cap boundary condition, circularly calculating a zero root value of an associated Legendre function, and when a distance between zero root values obtained viatwo adjacent calculations is smaller than a preset limiting value, ending the calculation, namely, realizing the extension of an order of a spherical cap harmonic model of an earth disturbance gravityfield. According to the method and system, orders of spherical cap harmonic models are extended to a certain extent, assignment precision of along-track disturbance gravity of spacecraft is improved,and benefit is brought to accurate navigation.

The invention discloses a method for establishing harmonic model of household electrical appliance load based on measured data, which comprises the following steps of acquiring measured voltage and current data of household electrical appliance load; performing Fourier analysis on the measured data to obtain the phasor values of each harmonic of voltage and current; obtaining the phasor values ofeach harmonic of voltage and current; establishing the harmonic model of cross frequency admittance matrix of household electrical appliance load; based on the generalized linear complex biased leastsquare method, calculating the parameters of the cross frequency admittance matrix model, and obtaining the cross frequency admittance harmonic model of household appliances by using the obtained voltage and current harmonic phasors as inputs. The method has the advantages of accuracy, rapidity, simplicity and practicability on the basis of no need to know the internal circuit structure and parameters of the household load, and has great significance for ensuring the accurate analysis and evaluation of the harmonic generation situation of the distribution network.

The invention relates to a power system harmonic flow algorithm giving consideration to uncertainty and three-phase unbalance, and the algorithm comprises the steps: selecting a harmonic order h; calculating an h-th order harmonic current value of a harmonic source injection system connected with a nonlinear load node; building an h-th order harmonic model of system elements comprising all circuits and a transformer; initializing a harmonic voltage and phase angle of each node; setting the number of interaction times, and calculating the equivalent injection harmonic current value of each linear load node in each iteration process; solving the sum of the branch harmonic currents from a tail node, and obtaining the harmonic current value of each phase of each branch circuit; sequentially calculating the harmonic voltage values of the nodes from the head end of a feed line to the tail end of the feed line, wherein an iteration ending criterion is that the deviation of the harmonic voltage of each node at each phase relative to the value at the last iteration is less than an allowed value; and solving the distortion rate of the harmonic voltage of each node at each phase according to an obtained fundamental wave voltage value and the value of each harmonic voltage.

The invention discloses a bow angle detection method based on CSI signal intensity in wifi. The method comprises the following steps: step one, configuring an AP and MP; constructing an experimental environment; preparing a commercial normal wireless network card driver, and a wifi router supporting 802.11n or above protocol; and configuring a CSI environment; step two, collecting data; and step three, processing the data; extracting a feature value reflecting a bow action by analyzing and processing channel state information CSI, and establishing a harmonic model; and finally classifying thebow angle action by utilizing a classifier, identifying and correcting the sitting posture, and realizing synchronous adjusting of the waist and cervical vertebra of the user; and reflecting the waistbending degree through the bow angle. The method disclosed by the invention is simple, free from carrying any sensor equipment and high in real time.

The invention discloses a forest biomass estimation method considering harmonic model coefficients and phenological parameters. The method comprises the following steps: S1, image acquisition and preprocessing; s2, establishing an MCCDC model based on multi-source remote sensing data; s3, forest annual phenology extraction based on a logistic regression equation; and S4, forest biomass mapping based on phenological parameters. Forest phenological parameters extracted based on remote sensing and a constructed harmonic model MCCDC coefficient serve as input variables of tree species classification and biomass modeling, optical remote sensing and radar images are coupled on the basis of improving the forest tree species group mapping precision, an optical-radar-phenological model is constructed according to tree species, and the forest species group mapping precision is improved. The defect that the influence of the tree species on the modeling precision is not distinguished during traditional AGB modeling is overcome to a certain extent, and therefore the precision of regional scale forest biomass mapping is improved.

The invention discloses an unmanned aerial vehicle ship autonomous landing method based on relative precision single-point positioning, relates to the field of high-precision relative position measurement, and can realize safe autonomous landing of an unmanned aerial vehicle ship in a complex meteorological environment. The method comprises the following steps of through an RPPP algorithm, establishing an unmanned aerial vehicle kinematics model and a harmonic model during ship motion, controlling transverse and longitudinal motions of the unmanned aerial vehicle, and introducing a relative motion equation between the two; proportional guidance and a linear quadratic regulator being combined, and accurate guidance being conducted on the pulling-up section of the landing tail end of the unmanned aerial vehicle. The method can be used for accurately determining the relative positions of the deck and the unmanned aerial vehicle under the conditions of violent shaking of the deck and drifting of the landing track of the unmanned aerial vehicle in a complex sea surface environment with stormy waves, so safe and autonomous landing of the unmanned aerial vehicle is realized.

The invention provides a harmonic parameter optimization method suitable for an offshore wind power transmission system through an alternating-current submarine cable network. The method comprises thefollowing steps: constructing a transfer function model of an alternating-current submarine cable network, and constructing a harmonic model and a transfer function model of a wind turbine generator;constructing a network transfer function model considering multiple fans and an alternating current submarine cable network; performing harmonic power flow calculation based on a network transfer function model, further calculating a network transfer function of a harmonic calculation point relative to a harmonic source, analyzing the influence of parameter change on harmonic amplitude accordingto the amplitude-frequency characteristic of the network transfer function, and further reducing the harmonic amplitude by optimizing parameters.

Power system harmonic analysis is to determine harmonic voltage and harmonic current in a system through calculation or judge whether a system is close to harmonic resonance state by calculating the frequency response of a network and calculate how to reduce the possibility of system resonance, which is according to a given power network structure, parameters and operation modes of a power network. The invention discloses a method for calculating harmonic wave and negative sequence current of an electrified railway, which builds harmonic models of common elements in the power network according to the practical situation of the power network. The invention also provides a novel equivalent method of a tractive power supply system, which converts a two-phase parameter of a tractive transformer and parallel compensation and traction load in the tractive power supply system into a three-phase parameter corresponding to a three-phase power system topological structure. The method of the invention determines harmonic models of all elements according to the operation modes of the power network, so as to perform corresponding calculation. The method in the invention particularly has a prominent advantage in calculating harmonic power flow and negative sequence current produced by the electrified railway.

The invention provides a delayed coking absorption stability optimization system based on an equation-oriented method. The system comprises a data acquisition module for collecting production processdata and laboratory analysis data and a calculation module which is connected to an output end of the data acquisition module, is formed by a harmonic calculation module and an economic optimization calculation module and outputs an optimization result. A simulation model of a strict mechanism model is established according to an actual delayed coking process, a data output end of the simulation model is connected to data input ends of a harmonic model of a harmonic target function established by using an EO method and an economic optimization model of an optimization target function established by using the EO method, a data input end and a data output end of the calculation module are connected to process simulation software, and a harmonic sub model and an economic optimization sub model are called through the process simulation software. The real-time calculation and optimization can be realized, the system has the advantage of a fast calculation speed, real-time optimization requirements are satisfied, material balance and energy balance are satisfied, and the system is simple to use and maintain by a web application program.

Disclosed is a method and system for utilizing a spherical cap harmonic model to determine disturbing gravity along an orbit. Before an aircraft is launched, with a first launching area as a sphericalcap area to be approached, the radius of a spherical cap is determined, and a spherical cap coordinate system is established; under the condition that an origin of coordinates is unchanged, the radius of the spherical cap is mapped to a hemisphere, and a new coordinate system is established; under the new coordinate system, a non-integral numerical value of a spherical cap harmonic expression iscalculated; on the basis of the non-integral numerical value, the spherical cap harmonic model is utilized to calculate the disturbing gravity under the new coordinate system; the disturbing gravity is converted into the original coordinate system, and the disturbing gravity of the aircraft along the orbit is obtained. By means of the method and system, the practical application effects of the spherical cap harmonic analysis model in studies of partial gravity fields are improved, under the condition of meeting the same accuracy, the speed of assigning the disturbing gravity of the spacecraftalong the orbit is increased, fewer memories are required, and mobile and quick launching is facilitated.

The invention discloses a remote sensing cultivated land change detection method and system considering phenological characteristics. The method comprises the following steps: constructing a pluralityof time series data sets according to time series vegetation indexes; processing each time series data set by adopting an improved MPFIT algorithm to obtain a processed time series data set; constructing a multi-harmonic model corresponding to each time series data set according to each processed time series data set and double-peak or multi-peak distribution characteristics of the cultivated land in consideration of phenological years; optimizing each multi-harmonic model to obtain a cultivated land phenology time sequence track model corresponding to each time sequence data set; calculatingthe change intensity of the cultivated land based on the phenological time sequence track model of each cultivated land; judging whether the cultivated land changes or not according to the change intensity. According to the invention, the original change detection based on two points is improved to change detection based on two phenological time sequence tracks, the accuracy, precision and robustness of change detection are improved, and the authenticity of change information is ensured.