9 results about "Discrete time domain" patented technology

The invention discloses a power distribution network multi-type flexible resource low-carbon scheduling method based on carbon emission flow, and relates to the technical field of power system low-carbon scheduling, and the method comprises the steps: constructing a scheduling time period set of a discrete time domain, and building an equivalent lossless network model; power flow calculation is carried out, and a node-branch carbon flow mapping relation is established; according to the carbon emission intensity of the unit, the carbon flow rate and node carbon emission flow of each branch are calculated; performing differential approximate calculation on the node injection power to obtain a carbon marginal coefficient of each node; generating a time-varying carbon price signal of each node in combination with an external carbon price reference; constructing a weighted combination objective function based on the node time-varying carbon price signal; and solving a weighted combination objective function and constraint conditions by adopting a distributed multi-agent collaborative optimization strategy. According to the invention, collaborative scheduling of multiple types of flexible resources under a low-carbon target is realized, and the carbon emission reduction effect is improved.

The application discloses a disturbance-resistant multi-agent discrete-continuous hybrid specified-time state estimation method, and belongs to the field of distributed state estimation of multi-agent systems, and comprises the following steps: S1, considering the state dynamics of the multi-agent system and the influence of external disturbance, a dynamic equation of the multi-agent system is constructed; S2, based on the dynamic equation of the multi-agent system, an augmented state estimation error equation and an extended state observer of the multi-agent system are constructed; S3, an estimation error dynamic equation in a discrete time domain is constructed, and the convergence of the augmented state estimation error is analyzed; S4, a discrete sampling interval is designed, so that the augmented state estimation error converges to zero within a specified time. The above-mentioned disturbance-resistant multi-agent discrete-continuous hybrid specified-time state estimation method can effectively cope with external disturbance, fuse the advantages of discrete and continuous time, be faster, more accurate and robust, and ensure that the state estimation of the multi-agent system is efficient and reliable.

The application belongs to the technical field of marine monitoring, and discloses a wave spectrum analysis method and system based on a laser radar.The method comprises the following steps: obtaining a plurality of concentric circles in the obtained wave field point cloud data; matching the discrete time domain signals of the wave height corresponding to the concentric circles and the derivative of the wave height with respect to time, and calculating the discrete values of the amplitude of the wave spectrum with respect to frequency; calculating unknown parameters in a directional spread function; and multiplying the discrete values of the amplitude of the wave spectrum with respect to frequency and the spread function to obtain the discrete values of the directional spectrum in frequency and direction, i.e., realizing the analysis of the wave spectrum. Through the application, the problem of realizing the analysis of the wave field spectrum and the directional spectrum by using point cloud data in the analysis of the wave field is solved.

This invention provides a method and apparatus for extracting the time-frequency characteristics of combined impact and corrugation defects in railway tracks. The method includes: determining a window length limit based on the discrete-time domain signal; using a third-order B-spline function as the window function for the Short-Time Fourier Transform (STFT) based on the discrete-time domain signal to determine the initial STFT time-frequency diagram and the initial Rayleigh entropy; utilizing the recursive property of the third-order B-spline function as the window function to determine the STFT result sequence and the Rayleigh entropy sequence of equal-length window sequences; determining the time-frequency transformation result and the optimal Rayleigh entropy based on the window length limit, the initial STFT time-frequency diagram, the initial Rayleigh entropy, the STFT result sequence, and the Rayleigh entropy sequence; and determining the time-frequency characteristics of the impact signal and the corrugation signal based on the time-frequency transformation result and the optimal Rayleigh entropy. This invention can simultaneously, quickly, and effectively extract the time-frequency characteristics of the impact component and the corrugation component in railway track defects and express them on a time-frequency diagram.

The invention discloses a frequency correction algorithm for a non-stationary signal, which is characterized in that a signal chain is specially designed, an original target non-stationary signal is divided into two paths after passing through a signal conditioning circuit, one path of signal x1 (t) is directly input to an analog-to-digital converter, and a discrete time domain signal x (n) is obtained after sampling by the analog-to-digital converter; the other path of signal passes through a waveform shaping circuit, a non-stationary signal is converted into a unipolar square wave digital signal x2 (t), the signal enters a digital processor with pulse capture and timer technical functions as a digital signal, and the digital processor can obtain a frequency value fc of the signal x2 (t) after passing through the waveform shaping circuit by adopting an equal-precision frequency measurement method; fc is defined as coarse frequency. Under the condition that all original time domain information of the signal is reserved, the judgment coefficient gamma is calculated by dividing frequency spectrum and power spectrum intervals, and the corresponding frequency correction formula is selected according to the value range of the judgment coefficient gamma, so that the accurate frequency correction of the non-stationary signal is realized, and the data measurement accuracy is improved.

The application belongs to the technical field of fuel cells, and discloses a hydrogen fuel cell equivalent circuit model parameter direct identification method. First, according to the response characteristics of the internal electrochemical reaction of the fuel cell in different frequency bands of the impedance spectrum, an R-(RC)-(RC)-(RC) equivalent circuit model and its frequency domain transfer function are established. Second, the continuous transfer function is converted into an input-output equation in the discrete time domain through variable substitution and bilinear transformation, forming an identifiable mathematical model of the to-be-identified parameters. Then, the recursive least squares method with a forgetting factor is used to identify the coefficients of the mathematical model in real time. Finally, all impedance parameters of the equivalent circuit are solved reversely based on the identification result, and an electrochemical impedance spectrum curve is drawn accordingly. The application only needs to use the output voltage and current data of the fuel cell during normal operation, without injecting any external excitation signal, so that the online rapid identification of the impedance parameters can be realized.

The invention discloses a radar ranging method based on frequency domain phase correction, which comprises the following steps: synchronously sampling a transmitted wave signal and a reflected wave signal to respectively obtain discretized time domain signals xt (n) and xr (n), windowing to obtain time domain signal sequences yt (n) and yr (n), and respectively carrying out FFT (Fast Fourier Transform) operation to obtain time domain signal sequences yt (n) and yr (n); a high-precision synchronous analog-to-digital converter is adopted to sample the transmitted wave signal and the reflected wave signal after frequency reduction at the same time to obtain an original time domain discrete signal, FFT is executed after windowing to obtain discrete spectrum data of the signal, and a correction coefficient is obtained through a special phase correction algorithm for calculation; after the phases of the transmitted wave and the reflected wave are corrected, a high-precision transmitted wave phase and a high-precision reflected wave phase are obtained respectively, a high-precision distance value is obtained through the relation between the phase difference and the distance, and high-precision radar ranging is achieved.

The application discloses an impedance automatic modeling method for a frequency-division offshore wind power system, which comprises the following steps: firstly, constructing a mathematical model of an element and linearizing the mathematical model to obtain a continuous time domain small signal model of the element, and discretizing the continuous time domain small signal model through trapezoidal integration to obtain a discrete time domain small signal model of the element; then, based on a correlation matrix and node analysis, converting the discrete time domain model at the element level to a system level model; finally, through z transformation and bilinear transformation, converting the discrete time domain model at the system level to a continuous frequency domain model at the system level, and realizing the above process through codes in a computer to automatically obtain the impedance of the system. The application replaces traditional manual symbolic derivation with numerical calculation, significantly improves the modeling efficiency, has good flexibility and expansibility, can be suitable for complex systems and new topological structures, provides an efficient stability analysis tool for the design and optimization of offshore wind farms and grid-connected systems, and can be extended to other renewable energy grid-connected systems containing multiple power electronic converters.

The invention provides a discrete time domain modal analysis method suitable for an alternating-current and direct-current hybrid system containing multi-port direct current and a related device, which are used for evaluating small disturbance stability and oscillation propagation characteristics of the system. The method comprises the following steps: firstly, constructing a whole-network discrete state matrix, and calculating a characteristic mode to judge a stability and instability mode serial number; determining a main influence area of oscillation through a node voltage observability matrix; and finally, determining an oscillation propagation path in the region by using the branch current observability matrix. According to the method, the limitation that a traditional method is only suitable for a two-port direct current system is solved, the method is expanded to a multi-port direct current scene, and support is provided for oscillation positioning, traceability and stability control strategy formulation of a complex system.