CN-120493053-B - Broadband impedance mode index calculation method

Abstract

The invention provides a broadband impedance mode index calculation method which comprises the following steps of S1, signal acquisition, S2, frequency band division, S3, calculating sub-band impedance, S4, stabilizing indexes, namely breaking through the limitation of a traditional method through multidimensional parameter fusion and dynamic collaborative optimization, adopting an improved wavelet packet decomposition algorithm to construct nonuniform frequency band division, realizing refined modeling of full-band impedance characteristics, fusing regularization constraint, sub-band impedance and phase data, synthesizing a total impedance mode, fusing dynamic stability margin into peaks of a total impedance mode, a stability margin and a total impedance mode curve, constructing a multidimensional stability evaluation model, and dynamically triggering a multistage response strategy based on the fused indexes.

Inventors

• HAN SHAOHUA
• LI JUAN
• LIU JIAN
• JIANG YUNLONG
• GE XUAN
• PANG JINIAN
• WANG XIURU
• DING LI
• Lv Shukang
• YU JIANYU
• YANG XIONG

Assignees

• 国网江苏省电力有限公司宿迁供电分公司
• 国网江苏省电力有限公司电力科学研究院

Dates

Publication Date

20260512

Application Date

20250428

Claims (4)

1. 1. The broadband impedance mode index calculation method is characterized by comprising the following steps of: s1, collecting signals, namely collecting voltage signals of a time domain of a point of connection And a current signal And for the collected voltage signal Current signal And sampling rate Preprocessing to obtain a processed signal; S2, frequency band division, namely adopting nonlinear expansion factors to the processed signals Dynamic adjustment of frequency bandwidth is realized, and the target frequency band is divided into at least 2 sub-frequency bands, namely, a low frequency band is generated <1, The bandwidth is 0.1-10Hz, the high frequency band 1, Wherein the bandwidth is 1-3kHz, and sub-bands are obtained; S3, calculating sub-band impedance, namely calculating sub-band impedance by adopting a regularized synchrophasor method; S301, segment processing is carried out on time domain voltage and current signals in each sub-band signal by applying a sliding time window, and fast Fourier transformation is carried out on signal fragments intercepted in each time window and is converted from the time domain to the frequency domain; s302, calculating the impedance of the sub-band by constructing and solving an optimized linear equation, and introducing a regularization optimization technology to solve; S303, based on noise variance estimation adaptive adjustment, the acquired parameters are attenuation coefficients of noise variance and exponential terms, phase delay compensation, and phase delay compensation for each sub-band Recording Amplitude of (a) of (b) And phase of Drawing a broadband impedance mode curve, and covering 0.1Hz to 3kHz; and S4, generating a global stability index based on frequency domain feature fusion of the dynamic stability margin.
2. 2. The method of claim 1, wherein the S3 sub-band impedance calculation further comprises regularizing the synchrophasor by performing a fast Fourier transform on each sub-band signal using a sliding time window to extract complex phasors at fundamental frequency And 。
3. 3. The method for calculating the modulus of broadband impedance of claim 2, wherein calculating the S3 sub-band impedance further comprises: regularized impedance calculation by constructing a linear equation and solving by regularized optimization ; Regularized optimization solution Is calculated as follows: ; Wherein, the Represented as subbands to be solved Is used to determine the impedance of the (c) signal, Represented as the conjugate transpose of the current phasors, Expressed as an identity matrix, dimensions and The same is true of the fact that, Expressed as matrix inversion, ensures numerical stability.
4. 4. The method for calculating the index of the wideband impedance modulus of claim 1, wherein the method is based on a global stability index The system stability was determined as follows: the value range of (2) is 0.8-0 Less than or equal to 1, expressed as system stability, the decision condition is that the stability margin of all sub-bands is Not less than 0.2, and the total impedance peak value does not exceed the reference value ; The value range of (2) is 0.5-0 <0.8, Expressed as a system light risk, determined on the condition that at least one sub-band <0.2, Or the total impedance peak value approaches the reference value ; The range of the value of (2) is within <0.5, Expressed as a high risk of the system, the judgment condition is any one of the sub-bands <0, Or the total impedance peak exceeds the reference value 。

Description

Broadband impedance mode index calculation method Technical Field The invention relates to the technical field of power system analysis, in particular to a broadband impedance mode index calculation method. Background As the permeability of new energy power generation (wind power, photovoltaic) continues to increase, the power system dominated by the power electronic converter presents significant broadband dynamic characteristics. The interaction between the new energy station and the power grid can cause novel stability problems such as subsynchronous oscillation (SSO), high-frequency resonance and the like in the frequency range of 0.1Hz-3 kHz. Conventional impedance analysis faces two major challenges: the frequency band coverage is insufficient, the resolution of the FFT method is limited in a low frequency band (the time window is required to be between 0.1 and 10Hz for >10 s), and the wavelet transformation has slow response to high frequency transient (the frequency band error is more than 1kHz for >10 percent); The noise sensitivity is high, and the power electronic switching noise (IGBT switching frequency is 2-20 kHz) causes impedance phase calculation jitter (+ -5 degrees) to influence stability margin evaluation. The prior art has the publication number of CN117910846A, and is named as an impedance model index calculation method and system for a new energy multi-feed system; the method comprises the steps of collecting power grid power flow calculation and impedance analysis technical field, defining impedance modulus indexes, constructing an equivalent impedance matrix of a multi-feed new energy grid-connected system, constructing a node impedance matrix of the system after the new energy is equivalent grid-connected based on system node voltage and current relation and the new energy equivalent, obtaining the impedance modulus indexes at the new energy nodes according to the new energy equivalent, and selecting new energy grid-connected capacity through the impedance modulus indexes. According to the impedance mode index calculation method for the new energy multi-feed system, provided by the invention, the intensity of the system static voltage stability of the new energy when different nodes are fed into the system is accurately indicated through the new energy node impedance mode index calculation, the calculation is realized through the equivalent impedance matrix, the impedance matrix is unchanged, repeated iteration is not needed, and the method has a better effect in the aspects of accuracy and applicability. In the prior art, although the impedance modulus index of the new energy node is calculated, the problems of combining frequency domain feature fusion, introducing noise, influencing stability margin evaluation and the like are avoided. Disclosure of Invention The invention aims to provide a broadband impedance mode index calculation method and method for solving the problems in the background technology. In order to achieve the above purpose, the present invention provides the following technical solutions: a broadband impedance mode index calculation method comprises the following steps: s1, collecting signals, namely collecting voltage signals of a time domain of a point of connection And a current signalAnd for the collected voltage signalCurrent signalAnd sampling ratePreprocessing to obtain a processed signal; S2, frequency band division, namely adopting nonlinear expansion factors to the processed signals Dynamic adjustment of frequency bandwidth is realized, and the target frequency band is divided into at least 2 sub-frequency bands, namely, a low frequency band is generated<1, The bandwidth is 0.1-10Hz, the high frequency band1, Wherein the bandwidth is 1-3kHz, and sub-bands are obtained; S3, calculating sub-band impedance, namely calculating sub-band impedance by adopting a regularized synchrophasor method; and S4, generating a global stability index based on frequency domain feature fusion of the dynamic stability margin. Further, the S3 sub-band impedance is calculated as follows: synchronous phasor extraction, namely applying sliding time window to each sub-band signal to perform fast Fourier transform, and extracting complex phasor at fundamental frequency And; Regularized impedance calculation by constructing a linear equation and solving by regularized optimization; Parameter selection and noise suppression, namely, self-adaptive adjustment is carried out on the basis of noise variance estimation, and acquired parameters are noise variance and attenuation coefficients of exponential terms; Dynamic error calibration, namely phase delay compensation; Subband impedance fusion and analysis for each subband RecordingAmplitude of (a) of (b)And phase ofAnd drawing a broadband impedance mode curve, and covering 0.1Hz to 3kHz. Further, based on global stability indexThe system stability was determined as follows: the value range of (2) is 0.8-0 Less than or equal to 1, exp