120 results about "Spectral leakage" patented technology

A resource block (RB)-based multicarrier modulation (MCM) transmitter and receiver structure for spectral agile systems are disclosed. The transmitter and the receiver are capable of sharing opportunistically available and non-contiguous channels with other users. The RB-MCM partitions the available spectrum, contiguous or non-contiguous, into multiple RBs (same or different sizes), applies a baseband MCM or single carrier modulation, or coded single carrier or multicarrier schemes in each RB with a type of spectral leakage reduction technique, and applies RB modulation for each RB to modulate the signal from baseband to the frequency band of that RB. At the receiver, the received signal may be filtered and RB demodulation may be applied to put each RB signal in baseband and a baseband multicarrier or single carrier or coded single carrier or coded multicarrier demodulation may be applied to each RB signal. Different RBs may use different modulation schemes.

The invention discloses a dynamic signal phasor measurement method based on time domain quasi-synchronization. The dynamic signal phasor measurement method based on the time domain quasi-synchronization comprises the following steps: estimating the fundamental wave frequency of a sampled signal by a time domain quasi-synchronization sampling algorithm; carrying out time domain quasi-synchronization on the sampled signal by the estimated value of the fundamental wave frequency; reconstructing a quasi-synchronization sampling sequence by Newton interpolation; carrying out frequency domain analysis on the reconstructed quasi-synchronization sampling sequence by FFT (fast Fourier transform) to obtain a dynamic signal phasor measurement result. According to the method, the influence on the measurement precision of the traditional phasor measurement method by frequency spectrum leakage caused by nonsynchronous sampling is avoided. The computation complexity of the dynamic signal phasor measurement method based on the time domain quasi-synchronization is smaller than the computation complexity of the traditional phasor measurement method based on the discrete Fourier transform, and the dynamic signal phasor measurement method based on the time domain quasi-synchronization is easy to realize in an embedded system.

The invention discloses a method for measuring electric network voltage flicker, and discloses a high-accuracy rapid flicker calculating method aiming at a non-integral cycle low sampling rate by taking account of errors probably caused by harmonic waves and electric network frequency. The core of the calculating method is that: a low fixed sampling rate is adopted to perform non-integral cycle sampling on electric network voltage waveforms, a cosine window is used for performing a fast Fourier transform algorithm (FFT), then the flicker frequency component is accurately extracted through a double-spectral line interpolation algorithm and a frequency spectrum searching algorithm, and the instantaneous flicker visual sensitivity is obtained through calculation. By using the method, under the condition of non-integral cycle low sampling rate, the errors caused by frequency spectrum leakage and harmonic wave aliasing are overcome, the frequency resolution is improved, the complexity of flicker calculation is effectively simplified, and a flicker measurement result is acquired quickly. By using the method, the performance requirement of hardware of an analog-digital converter, a processor and the like is reduced, thus the cost of a flicker measuring instrument is reduced, and simultaneously the measuring accuracy is improved; and besides, the method is applicable to fast low-cost measurement of the electric network voltage flicker, and has a very good effect.

The invention discloses a power system interharmonic wave detection method based on MUSIC spectrum estimation and a HBF neural network, comprising the steps of getting sampling data of detected signals by an analog-to-digital converter, getting various harmonic waves and interharmonic wave frequency contained in the signals through MUSIC spectrum estimation, and getting amplitudes and phases of the harmonic waves and the interharmonic waves through the adaptive adjustment of weights of the HBF neural network. The invention first provides the power system interharmonic wave measurement method based on the MUSIC spectrum estimation and the HBF neural network. The invention has the advantages of high frequency resolution without causing frequency spectrum leakage, high measurement precision of frequency, amplitudes and phases of the harmonic waves and the interharmonic waves, and high learning speed of the weights of the neural network, and is adaptive to on-line monitoring and off-line testing of interharmonic waves in the power system.

The invention discloses a high-precision harmonic parameter estimation method based on a composite iterative algorithm. The method comprises the steps as follows: firstly, a harmonic amplitude value is directly calculated by utilizing a three-peak interpolation algorithm, and meanwhile, a harmonic phase is calculated to serve as an initial phase value for composite iteration, then the initial phase value is transmitted to a phase difference correction algorithm to obtain a frequency deviation value by utilizing the phase difference correction algorithm, and the phase difference correction algorithm is combined with a spectral leakage cancellation algorithm so as to obtain a phase value for the first-time iterative computation; circulating iteration is performed between the phase difference correction algorithm and the spectral leakage cancellation algorithm repeatedly until a phase iteration result meeting the error limit requirement is obtained. According to the invention, with the adoption of the three-peak interpolation algorithm, the estimation precision of the harmonic amplitude value is improved, and the phase obtained by utilizing the three-peak interpolation algorithm serves as an initial value, and the phase difference correction algorithm and the spectral leakage cancellation algorithm are combined to construct the composite iterative algorithm, so that the estimation precision of a harmonic phase and frequency is greatly improved.

The invention discloses a high-accuracy sinusoidal signal measuring device for removing frequency spectrum leakage, comprising an analog signal pre-processing unit, a data acquisition unit, a digital signal processing unit, a measuring result display unit, and a communication interface unit, wherein the analog signal pre-processing unit is connected with the data acquisition unit through multipath signal wires, and the digital signal processing unit is connected with the data acquisition unit, the measuring result display unit and the communication interface unit respectively through an SPI (Serial Peripheral Interface) bus. The measuring method comprises the steps of: 1, continuously sampling a signal to be measured to obtain sequences S1 and S2; 2, carrying out fast Fourier transform onthe S1, extracting a peak frequency spectrum and obtaining the peak frequency spectrum of the S2 through recursion; 3, calculating the frequency of the signal to be measured by applying the peak frequency spectrums of the S1 and the S2; 4, calculating the phase of the signal to be measured according to the phase angle information of the peak frequency spectrums of the S1 and S2; 5, solving an equation set relevant to positive and negative frequency spectrum amplitudes to obtain the measured value of the amplitude of the signal to be measured; and 6, removing the influence of the frequency spectrum leakage to obtain the accurate measured valve of a direct-current component.

Disclosed is an inter-cell interference mitigation method using a spatial covariance matrix (SCM) estimation method in a multi-input multi-output (MIMO) orthogonal frequency division multiplexing (OFDM) communication system for mitigating interference between asynchronous cells. The inter-cell interference mitigation method includes extracting a reference symbol (RS) of a received OFDM symbol and performing channel estimation, estimating an initial SCM using the RS signal and the channel estimation result, applying time-domain sinc type weighting to the initial SCM and applying an SCM, and demodulating a data symbol with mitigated inter-cell interference using the channel estimation result and the estimated SCM. By applying time-domain sinc type weighting to SCM estimation, it is possible to reduce an SCM estimation error occurring due to a spectral leakage induced by an abrupt change in a signal at a border point between an effective sub carrier zone and a guard band zone, and a simple design of a moving average filter form for a frequency domain signal can be made instead of frequency-time-frequency domain transformation using an inverse fast Fourier transform (IFFT) and fast Fourier transfer (FFT).

The present invention provides a unicast and multicast orthogonal frequency and time division multiplex emitter including: a inverse Fourier transform device, a data block multiplexing device, a protective gap adding device and also includes a sub-carrier mapping device positioned before the inverse Fourier transform device for mapping each element in the symbol data block to the corresponding effective carrier in the inverse Fourier transform device to transmit and 0 is transmitted to the sub-carrier having no data mapping; and a forming filter device positioned after the protective gap adding device for performing a form filtering to the OFTDM signal wave to be sent according to the frequency spectrum module. Said forming filter is an over-sampling FIR filter for satisfying the requirement of the leak of out-off-band frequency spectrum of the system. The present invention can solve the technique problem of the leak of out-off-band frequency spectrum of the system.

The invention discloses a phase difference correction method applied to self-adaptive sampling of a power grid having a wide range of frequency fluctuation. The method overcomes lower measurement precision of phase difference correction methods upon dynamic variation of a fundamental frequency by increasing computing of frequency change rate, predicting real-time fundamental frequency for each measurement, correcting sample frequency so as to carry out measurement. Therefore, the method herein effectively reduce spectral frequency leakage and increases measurement precision. The method herein conducts simulation analysis on variety-frequency power grid signals by using phase difference correction method which is based on Harming window, verifies the feasibility of self-adaptive sampling methods. The method can produce high magnitude and phase measurement precision when a frequency is stable, and can also reach IEC standard requirements for magnitude measurement precision when the fundamental frequency has wide range of fluctuation, so that the method herein effectively reduce phase difference errors, can real-time reflect state of a system, and is suitable for on-line monitoring harmonic waves of a power grid which has a wide range of frequency fluctuation.

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.

The utility model provides a reconstruction method for the high speed signals of the oscillograph, belonging to the technical filed of the high speed broad band oscillograph, which comprises sampling the original tape limit signal x (t) to get the sequence x (n), inserting a plurality of zero value spots in equal space between two neighboring actual sampling points to get a new sequence m (n); carrying on low-pass filtering to the frequency spectrum M (ejOmega) of the m (n) with the interpolation filter and then separating the baseband weight X (ejOmega) of the original signals; making fourier inversion to the baseband weight X (ejOmega) to get the interpolation signals of the original signals; wherein, the interpolation filter is constructed with the method of frequency-domain sampling. Comparing with the traditional reconstruction method for the high speed signals, the utility model has the advantages of enabling to effectively revise the waveform distortion because of the divulging of the frequency spectrum, and achieving the aim of reconstructing the original signals in high quality due to the physical feature of output signals are completely consistent with the original signal.

The invention discloses a synchronous phasor measuring method suitable for an M-class PMU unit. The method includes the steps that a low-pass digital filter regarding a phasor factor is combined with disperse Fourier transform (DFT) algorithm, and an original phasor measured after spectrum leakage is eliminated is worked out; fitting is carried out on the dynamic phasor through second order Taylor series, the measurement error caused by the DFT equalization effect is obtained, compensation is carried out on the original phasor based on the error, and the precise dynamic phasor measurement is obtained; the low-pass digital filter regarding the M-class phasor measurement unit (PMU) is arranged at the phasor uploading position, the precisely measured phasor is used as input, and the final measured phasor is obtained. By means of the synchronous phasor measuring method, when the input is a static signal or a dynamic signal, phasor measurement can be carried out precisely and quickly, and the phasor accuracy can meet the requirements of IEEE C37.118.1, and is higher by an order of magnitude generally.

The present invention relates to a BDPD-based method for improving efficiency of RF power amplifier, comprising: first, choose key neural network architecture and scale and input initial values of modeling data and network parameters necessary for establishing the neural network model for RF power amplifier; second, correct network parameters with back propagation method and output the neural network model for RF power amplifier when the error meets the criterion; next, solve the pre-distortion algorithm of the RF power amplifier with said model and then carry out pre-distortion processing for the input with the pre-distortion algorithm and feed the input to the RF power amplifier. The present invention can be used to establish a neural network model with adequate accuracy and easy to solve corresponding pre-distortion algorithm for RF power amplifier, in order to improve RF power amplifier efficiency, reduce costs, and suppress out-of-band spectrum leakage effectively through base-band digital pre-distortion technology.

The invention relates to a time shift phase difference steady harmonic signal correction method based on a Nuttall window and belongs to the harmonic wave analysis field; the method adopts the Nuttall window for weighting the harmonic signal and combines the phase difference correction theory for obtaining the frequency correction amount for correcting and analyzing the harmonic wave. The time shift phase difference steady harmonic signal correction method based on the Nuttall window can restrain the base wave caused by the spectrum leakage and the mutual interference among the integer harmonic waves, compared with the harmonic wave analysis specific value correction method and the other window parameter, the time shift phase difference steady harmonic signal correction method based on the Nuttall window can obtain higher calculation precision at the same signal truncation time.

The invention provides a harmonic detection method based on Nuttall window four-spectral-line interpolation FFT (fast Fourier transform). The method comprises steps as follows: (1), a time-domain signal is subjected to discrete sampling, a discrete signal sequence is obtained, a four-term three-derivative Nuttall window is selected to perform windowing processing on the discrete signal sequence, FFT analysis is performed, and a value of each discrete frequency point is obtained; (2), a maximum frequency point value and a submaximal frequency point value are selected nearby each peak frequency point spectral line according to the value of each discrete frequency point, a maximum amplitude spectral line and a submaximal amplitude spectral line nearby each peak frequency point spectral line as well as two peripheral spectral lines are found out according to the maximum frequency point value and the submaximal frequency point value, and amplitudes of the four spectral lines are obtained; (3), a amplitude correction formula, a frequency correction formula and a phase correction formula of four-spectral-line interpolations are derived according to the amplitude information of the four spectral lines. The spectrum leakage inhibition effect is good, the correction errors are small, and the harmonic analysis precision is high.

The invention provides a method for processing a signal. The method includes the steps of conditioning the original signal according to preset conditioning conditions to obtain an analog signal; carrying out A / D conversion on the analog signal to obtain a digital signal; carrying out spectral analysis on the digital signal with an FIR algorithm and an FFT algorithm to obtain a first signal; correcting the frequency and the amplitude of the first signal with a preset correcting algorithm to obtain a second signal; compensating for the amplitude of the second signal according to a preset compensation rule to obtain a third signal, and outputting the third signal to a calculation device. By means of the method, after spectral analysis is carried out on the digital signal with the FIR algorithm and the FFT algorithm, the frequency and the amplitude are corrected, and the amplitude is compensated. The signal is corrected, spectrum leakage of the FFT algorithm is reduced, and meanwhile the picket fence effect of the FFT algorithm is buffered; amplitude compensation is carried out on the signal, FIR band-pass fluctuation and transition band attenuation are overcome, and the accuracy of the signal processing result is improved.

The invention discloses a sub-synchronous and super-synchronous harmonic parameter processing method based on PMU implementation. Current signals containing sub-synchronous and super-synchronous harmonic parameters in A / D acquisition are resampled, can be used for analyzing sub-synchronous harmonic parameters and can be also used for analyzing super-synchronous harmonic parameters, a frequency spectrum of an FFT is corrected by using a Grandke frequency spectrum correction method, a picket fence effect and a frequency spectrum leakage phenomenon in frequency spectrum analysis of the FFT are overcome, the identification precision of oscillating component parameters is greatly improved, the software and hardware expenditures on a WAMS master station side are reduced to some degree, reliable raw data and data support are provided for functions such as power grid wide-area monitoring, automatic substation measurement and control, stability control and self-adaptive relay protection of a whole system, and the sub-synchronous and super-synchronous harmonic parameter processing method has a good application prospect.

The invention discloses an adjacent harmonic and inter-harmonic separation and measurement method under an IEC (international electrotechnical commission) framework. The method includes the following steps: firstly, performing discrete sampling on a power grid signal; secondly, performing ten-cycle Hanning window addition DFT / FFT (discrete Fourier transform / fast Fourier transform) spectral transformation on a sampling value according to IEC standards so as to obtain a spectrum; thirdly, multiplying the spectrum by rotary phase factors to obtain a new spectrum; fourthly, solving a vector sum of neighboring spectral lines of the new spectrum so as to offset sidelobe interference of rest components on the new spectrum, and solving corresponding frequency, a frequency deviation value and amplitude phase via a spectral line phase cancellation interpolation method; fifthly, rejecting spectrum leakage values of a fundamental component and the rest components at spectral line attention positions on a frequency domain; sixthly, solving a harmonic spectrum value to obtain parameters of h subharmonics, and solving parameters of inter-harmonics adjacent to the h subharmonics. By the method, the problem that the parameters of the two adjacent harmonics and inter-harmonics cannot be measured accurately during limited data asynchronous sampling is solved.

The invention relates to the field of voice communication, and discloses an elimination method and system of remaining echoes. Windowing processing is carried out on the remaining echoes by adopting a Hamming window or a Blackman window or other non-rectangular window, spectrum leakage can be reduced so that accuracy of linear prediction can be improved, residual error signals are made to be more similar to white noise, and therefore the remaining echoes can be eliminated better. Further, when the windowing processing is carried out on the residual echo signals, remaining echo signals of a base frame and the last N signals of a last frame can be combined to form the remaining echo signals needing to be process at present, and the spectrum leakage can be further reduced.

The invention discloses a navigation anti-interference algorithm combining threshold processing and a space-frequency adaptive algorithm, and belongs to the field of satellite navigation communication. The algorithm enables a threshold processing algorithm and the space-frequency adaptive algorithm to be combined together, carries out the threshold preprocessing of a signal converted into a frequency domain at first, and then carries out the space-frequency adaptive processing, thereby effectively improves the capability of resisting narrow-band strong interference of an anti-interference system. Meanwhile, the algorithm employs a method of two-channel data stack windowing for the anti-interference processing of the signal during the space-frequency adaptive processing, effectively reducing the impact on spectrum leakage from a conventional space-frequency adaptive algorithm, and improving the performance of a system.

The invention provides a power system frequency calculation method of windowing spectral line interpolation. The method includes the following steps that 1, voltage sampling data of ten continuous sampling cycles of a public connection point are obtained through a voltage measurement circuit; 2, time domain windowing function processing is conducted on the voltage sampling data; 3, local discrete Fourier transformation is conducted on the data obtained after windowing, and voltage amplitude values of specific harmonic wave times are obtained; 4, for the calculated specific voltage amplitude values, interpolation is conducted between the two adjacent maximal amplitude values; 5, calculation is conducted through a polynomial curve fitting method, a frequency coefficient is obtained, and thus fundamental wave frequency of a power grid is determined. By means of the method, a blackman window function is applied to N sampling points, local discrete Fourier transformation (DFT) is only conducted on designated harmonic frequency , it is proved through experiments that by means of the method, the spectrum leakage inhibition effect is good, the calculation speed is high, the calculation process is simple, precision is high, universality is high, and the method can be used for high-precision electric energy metering and electric energy quality analysis.

A synchrophaser measurement method applied to a P Class Phasor Measurement Unit (PMU), and is based on the dynamic phasor mathematical model. The method includes providing a low pass digital filter for phasor factors and applying Discrete Fourier Transform, so that the spectrum leakage caused by the dynamic phasor inputs is eliminated, and the raw phasor measurements after the spectrum leakage being eliminated can be obtained. In addition, the dynamic phasor inputs are fitted by using the second order Taylor series and the linear relationship between the measurement errors causing the Discrete Fourier Transform averaging effect and the second order coefficients of the Taylor series is explored. The linear relationship is used to correct for the raw measurement errors under a dynamic condition, and the accurate dynamic phasor measurements can thus be obtained. This measurement method can measure phasor accurately and rapidly under both static and dynamic conditions.

Systems and methods for digital signal processing using a sliding windowed infinite Fourier transform (“SWIFT”) algorithm are described. A discrete-time Fourier transform (“DTFT”) of an input signal is computed over an infinite-length temporal window that is slid from one sample in the input signal to the next. The DTFT with the temporal window at a given sample point is effectively calculated by phase shifting and decaying the DTFT calculated when the temporal window was positioned at the previous sample point and adding the current sample to the result. The SWIFT algorithms are stable and allow for improved computational efficiency, improved frequency resolution, improved sampling, reduced memory requirements, and reduced spectral leakage.

The invention discloses a fault diagnosis method for an anti-interference rotating machine. The method comprises the steps that a fault data signal of the rotating machine is preprocessed; a Meyer wavelet filter group is adopted for decomposing the signal in step 1; a multi-decoloring cycle harmonic rate value of each sub-band in a decomposition tree in step 2 is calculated; a square envelope spectrum parsing a sub-signal with the largest multi-decoloring cycle harmonic rate value in a multi-decoloring cycle harmonic rate diagram is selected as a diagnosis result; if a multi-decoloring cycle harmonic rate is greater than 2 times of a historical value, it is diagnosed that the probability of a fault in a diagnostic object is greater than 80%. The multi-decoloring cycle harmonic rate is constructed to characterize a band signal-to-noise ratio, is used for replacing a spectral kurtosis index in a fast spectral kurtosis diagram; a Meyer wavelet filter adopted in a wavelet is used for decomposing the signal to replace an FIR filter in the fast spectral kurtosis diagram, and the Meyer wavelet filter can solve the spectral leakage problem in the center of an analysis frequency of a wavelet packet.

The invention relates to a method which reduces the orthogonal frequency division multiplexing signal spectrum leakage, belongs to the technical field of wireless and wire communications using orthogonal frequency division multiplexing (OFDM) signals, and aims at having lower achievement complexity, causing only small inference to the data sub-carrier of the OFDM signals and effectively reducing the signal spectrum leakage. The input data of the invention can obtain a time-domain sequence si(n) of the OFDM signals through serial-parallel conversion, inverse discrete fourier transform and parallel-serial conversion, plus cyclic prefix and guard interval, and generate a time-domain sequence ci(n) of the optimal offset signals to the si(n), and then superimpose the ci(n) and the si(n) which are then transmitted by a transmitter. In order to reduce compute complexity and reduce the interference of the offset signals to the data sub-carrier in the si(n), two offset signal producing methods are provided; the method of the invention reduces the OFDM signal spectrum leakage, improves the spectrum resource utilization rate, and can also be applied to the communication system using the multi-carrier technology.

The invention discloses an APF harmonic detection method based on a spectrum leakage correction algorithm. Based on the traditional discrete Fourier transform, the method uses the signal truncation length as an independent variable, extends the classical one-dimensional amplitude spectrum into two dimensions, provides a new way for signal spectrum characterization, and adopts a spectrum leakage correction algorithm based on the minimum error to achieve accurate estimation of the frequency, amplitude and phase. Compared with the prior art, the method of the invention obtains N closest to the integral cycle truncation through the two-dimensional spectrum, on this basis, obtains approximate accurate estimates of the signal frequency, amplitude and phase based on the minimum error theory by taking the spectral value constructed by sinc as a real spectrum, and has the advantages of small error and easy implementation.

The invention discloses a method for discriminating the property of a single-phase fault of a power transmission line with a parallel electric reactor. The method comprises the steps: 1, carrying out uninterrupted sampling for a recovery voltage u of a head end at a fault phase when a single-phase grounding fault happens and the fault phase enters into a recovery voltage stage after arc blowout, and obtaining a sampling value sequence [u1(n)] of the recovery voltage u1(t); 2, comparing the amplitudes of all sampling points in the sampling value sequence [u1(n)] one by one, determining the minimum value Umin, the maximum value Umax, the time tmin corresponding to the minimum value Umin, and the time tmax corresponding to the maximum value Umax in all maximum value points, extracting all other maximum value points between the minimum value Umin and the maximum value Umax, calculating kset and the slope between two adjacent positive extreme points, and determining the minimum value kmin; determining that the single-phase fault is a transient fault if kmin is greater than kset; or else, determining that the single-phase fault is a permanent fault. The method employs a recovery voltage construction as judgment basis, can be easily achieved, effectively inhibits the spectrum leakage and picket fence effect of a DFT algorithm, shortens the time in determining the property of the fault, is high in response speed, and meets the demands of quick reclosure.

The invention discloses a time error estimation and correction method for a TIADC collection system. High frequency standard sinusoidal excitation is carried out on the TIADC system, thereby obtainingsampling data of each ADC. Spectrum leakage-free FFT is carried out on the sampling data of each ADC, thereby obtaining spectrums. A phase spectrum value of each ADC is precisely obtained through utilization of a frequency domain folding theory. A time error estimated value is obtained through utilization of the phase spectrum value of each ADC. The estimated values are corrected to obtain time error corrected values. A TIADC time error is corrected according to the time error corrected values and phase adjustment units in the ADCs.

The invention discloses a novel harmonic high-precision detection method. The method comprises: establishing a novel time-frequency filter, restraining frequency of a minus semiaxis by Hilbert transformation, and detecting frequency, amplitude, and phase positions of each subharmonic and inter-harmonics by a time domain convolution method in a high precision manner. From theoretical analysis basis and calculation formula derivation of the method, the method prevents Fourier (FFT) region spectrum leakage, picket fence effect, and non-integral subwave phenomenon. Results of experiment simulation shows that the time domain filtering convolution method is flexible in design and realization, and convenient in engineering real-time realization, and overcomes influence of fundamental frequency on harmonic analysis, and detection precision of frequency, amplitude values, and initial phases of signals including multiple harmonics and inter-harmonics. Frequency, amplitude, and phase of a voltage flicker signal can be obtained by a signal converting equation. For flicker signals polluted by the inter-harmonics, detection results are not influenced.

The invention discloses a loop signal analysis method and a device for a DC control protection board, which relate to the technical field of signal processing and aim at solving the problem that spectrum leakage generated during a loop signal analysis process can not be effectively restrained. The method mainly comprises steps: according to a preset sampling frequency, board loop signals are sampled uniformly, and discrete signals are acquired; the discrete signals are intercepted according to a mixed convolution window, and filter signals are acquired; the result of carrying out FFT (Fast Fourier Transformation) on the filter signals is determined to be a harmonic spectrum; in the harmonic spectrum with the distance with a preset basic frequency point to be smaller than preset frequency offset, a peak frequency point nearest to the preset basic frequency point and with the maximum amplitude is searched; according to the amplitudes corresponding to the preset basic frequency point and the peak frequency point, the amplitude offset is calculated; and according to the offset, every-order harmonic parameters in the harmonic spectrum are calculated, wherein the harmonic parameters comprise the amplitude, the phase and the frequency. The method and the device are mainly applied to loop signal analysis for the DC control protection board.