9 results about "Characteristic polynomial" patented technology

The invention relates to the technical field of new energy grid-connected stability control, in particular to a small-signal steady-state discrimination method and system for a double-fed wind power plant controlled by a virtual synchronous machine and a medium, and the method comprises the steps: building a linear state space model for a double-fed fan controlled by a single virtual synchronous machine; listing a characteristic polynomial, and deducing a single-machine stability criterion inequality by using a Routh criterion; the method comprises the following steps: constructing a full-order state space matrix for a doubly-fed wind power plant comprising M units; decomposing the matrix into M independent subsystems, and performing eigenvalue decomposition on the current collection network impedance matrix to obtain a maximum eigenvalue; the M independent subsystems are equivalent to M-1 isolated subsystems without network interaction and an equivalent single-machine subsystem; and carrying out Routh criterion derivation on the equivalent single machine subsystem to obtain an explicit stability criterion inequality of the double-fed wind power plant grid-connected system and carrying out steady state discrimination. According to the invention, the problem that the stability boundary cannot be explicitly displayed under the complex power grid topology in the prior art is effectively solved.

The application provides a wideband measurement method and device based on a Prony algorithm, the method comprising: collecting time window data of a target power signal and constructing a sampling sequence; constructing a Hankel matrix based on the sampling sequence, separating the Hankel matrix into a low-frequency part and a high-frequency part through frequency analysis on frequency components; performing resampling processing on the low-frequency part of the Hankel matrix; for the resampling-processed low-frequency part, constructing a characteristic polynomial by using the Prony algorithm, and obtaining an initial frequency of each frequency component by solving the characteristic polynomial. The application solves the problem that current wideband measurement algorithms cannot accurately reflect the dynamic change characteristics of signals in a short time window and cannot accurately measure.

This invention discloses a method, system, and device for identifying subsynchronous oscillation modes under environmental excitation, belonging to the field of power system oscillation detection. Kalman filtering (KF) is used to estimate the coefficients of an autoregressive (AR) model to fit measured environmental data. The damping factor and frequency of the subsynchronous oscillation (SSO) mode can be directly obtained by solving for the roots of the characteristic polynomial corresponding to the AR model. Furthermore, multi-model segmentation filtering (MMPF) is applied to KF to select the correct AR model order. This invention combines the KF algorithm with MMPF, enabling the algorithm to directly identify weak SSO mode parameters from environmental data. The method has simple operation steps and short response time, thus possessing good application prospects.

This invention discloses a method and system for identifying hydrological anomalies in water conservancy projects, belonging to the field of data processing technology. The invention collects hydrological observation data and maps monitoring sections as graph nodes, calculates the cross-sectional specific energy to construct transient graph signal vectors and unsigned topological Laplace matrices; calculates the global scheduling ground-state signal vector based on matrix polynomial expansion and performs differential operations to remove interference from compliant high-flow scheduling, obtaining local disturbance residual signal vectors; calculates the evolution rate by extracting algebraic invariants of characteristic polynomials, dynamically generating filtering boundaries; uses Chebyshev polynomial approximation to construct a bandpass graph filter to filter the residual signals, retaining structural anomaly signal vectors representing local structural damage; calculates the transient energy sequence vector and compares it with the energy alarm threshold to accurately identify abnormal physical nodes and generate alarm information. This invention eliminates compliant scheduling interference and achieves high-precision perception and positioning of physical structural disasters.

The application discloses a signal delay estimation method based on block processing, comprising the following steps: acquiring CSI data and preprocessing (validity test, noise filtering, selecting valid index); obtaining overlapping data blocks by block processing according to a preset block quantity and overlapping ratio; building Hankel matrix and enhancement matrix for each block, and obtaining delay estimation value through singular value decomposition, subspace separation and characteristic polynomial solving; assigning weight to each estimation value in combination with signal quality evaluation; and determining the final result based on the delay estimation value and weight information. In the application, a large matrix is disassembled through block overlapping, the singular value decomposition complexity and storage occupation are reduced, and lightweight hardware is adapted; the processing time consumption is shortened, the real-time demand in multiple scenes is met, the application can be run on ordinary equipment, and positioning deviation caused by delay is avoided.

The invention discloses a micro-grid secondary frequency modulation controller parameter optimization method and a related device, and belongs to the technical field of micro-grid stability analysis and control, and the method comprises the steps: firstly obtaining a model and parameters of a micro-grid, and building a time-delay differential algebraic equation which comprises primary and secondary frequency modulation and considers the communication delay influence; secondly, processing a time delay term by adopting Pade approximation to form a discretization matrix, and carrying out simultaneous operation on the discretization matrix and a time delay differential algebra to obtain a discretization model; next, all characteristic values of the discretization model are calculated through a QR method, and the rightmost characteristic value of the discretization model is used for approximately replacing the rightmost characteristic value of the time-delay differential algebraic equation; and then forming a discrete model characteristic polynomial, and calculating a time lag margin by using a Routh criterion. And finally, under the condition of considering the balance between the damping performance and the time lag margin of the system, establishing an objective function and a constraint condition of controller parameter optimization, and obtaining optimized controller parameters by adopting a genetic algorithm. The method can ensure that the system has good robust stability for time delay while meeting the corresponding damping performance.

The application belongs to the technical field of magnetic field measurement, and particularly relates to a magnetic target positioning method based on a magnetic gradient full tensor, which comprises the following steps: step 1, measuring the magnetic gradient full tensor at two observation points; step 2, solving the characteristic polynomial of the magnetic gradient tensor matrix at the two observation points, and calculating the corresponding real characteristic value and the corresponding unit eigenvector; step 3, calculating the normalized magnetic source intensity corresponding to the two observation points, the cosine of the angle between the relative position vector and the magnetic moment vector, and the cosine of the angle between the plane P1 and the plane P2; step 4, calculating the cosine value of the angle between the relative position vectors at the two observation points, and the modulus value of the relative position vector; step 5, establishing an equation group, and solving the unit direction vector of the relative position vector; and step 6, determining the magnetic source position. The application is convenient to measure, simple to calculate, and high in accuracy.

The present specification relates to the technical field of wellbore trajectory design, and provides a double-arc three-dimensional wellbore trajectory design method and device. The method comprises: obtaining a double-arc three-dimensional wellbore trajectory design model and corresponding constraint conditions; determining associated parameters corresponding to a target azimuth angle according to the constraint conditions; performing mapping transformation on the constraint conditions and the associated parameters by using a preset mapping transformation formula to obtain a target characteristic polynomial; calculating all real roots of the target characteristic polynomial; when the number of the real roots is greater than a preset threshold, analyzing the effectiveness of each real root based on the constraint conditions to obtain a design result of the target azimuth angle and a corresponding double-arc three-dimensional wellbore trajectory. Through the embodiment of the present specification, the stability of double-arc three-dimensional wellbore trajectory design can be improved.

The invention discloses a method for calculating the inherent frequency of a rotating motor under an operation condition, discloses a method for acquiring the inherent frequency of the rotating motor under the operation condition, and belongs to the technical field of online recognition of modal parameters of a motor structure. The method comprises the following steps: uniformly distributing N more than or equal to 4 unidirectional vibration sensors on a stator tooth part; the motor operates with load and synchronously collects vibration signals; carrying out zero-phase band-pass filtering on the signal; calculating a cross-correlation function of the reference point and the response point, and carrying out complex modal modeling to form a complex index series; constructing a matrix equation through unilateral cross-power spectrum transformation and multi-start time sampling, and obtaining a coefficient vector through SVD solution; and constructing a characteristic polynomial by a coefficient to obtain root, mapping to obtain continuous poles of the system, and outputting the inherent frequency and the damping ratio at the same time. The whole process does not need to be stopped, external excitation is not needed, the noise immunity is high, the frequency recognition error is smaller than 1%, and modal data under the real boundary condition is provided for motor NVH optimization and structure modification.