Impedance / admittance measurement error evaluation method and system

Abstract

The invention relates to the technical field of impedance / admittance measurement error evaluation, in particular to an impedance / admittance measurement error evaluation method and system, and the method comprises the steps: collecting a noise signal of target equipment, and calculating the probability distribution of a noise amplitude; performing frequency sweep measurement on the target equipment, obtaining frequency sweep response signal amplitudes under various frequencies by injecting disturbance signals under various frequencies, and calculating probability distribution of a noise-signal ratio # imgabs0 # under various frequencies; constructing an expression for calculating and measuring the relative error # imgabs1 # through an inversion method or a decoupling method; decomposing an expression for calculating the measurement relative error into an expression molecule and an expression denominator, and respectively calculating probability distribution of an expression molecule modulus value # imgabs2 # and an expression denominator modulus value # imgabs3 #; and converting the expression sub-modulus value # imgabs4 # and the expression denominator modulus value # imgabs5 # into a logarithmic coordinate system, and calculating the probability distribution of the measurement relative error in the logarithmic coordinate system. According to the invention, efficient and accurate measurement error evaluation and disturbance signal optimization in a low-internal-resistance scene of equipment can be realized.

Description

Technical Field

[0001] This application relates to the technical field of impedance / admittance measurement error evaluation, and particularly relates to a method and system for evaluating impedance / admittance measurement errors. Background Art

[0002] With the rapid development of new energy power generation, the penetration rate of power electronic devices in the power system has increased significantly, and the system stability problem has become increasingly prominent. As the mainstream method for analyzing the stability of power electronic systems, the impedance method focuses on obtaining the impedance characteristics of devices through sweep frequency measurement. However, in actual measurement, noise interference will directly affect the impedance measurement accuracy. Especially in the multi-frequency injection scenario, the energy of the disturbance signal is dispersed, resulting in a decrease in the signal-to-noise ratio, which further exacerbates the impact of noise on the measurement results. How to quantitatively evaluate the measurement error caused by noise has become a key challenge in improving the reliability of the impedance method.

[0003] In the prior art, for the problem of measurement error caused by noise, the decoupling method, the improved decoupling method, and the matrix inversion method are mainly used for sequence impedance calculation. The decoupling method decouples the sequence admittance matrix by injecting positive sequence and negative sequence disturbance signals in turn. The improved decoupling method adds the calculation of the sub-diagonal elements on this basis to improve the accuracy, while the matrix inversion method constructs the admittance matrix by injecting two linearly independent disturbance signals. In addition, the Monte Carlo experiment method is used to evaluate the error confidence level, and the influence of noise is simulated through a large number of random samplings. These methods attempt to solve the noise interference problem from different angles and have achieved certain effects in specific scenarios.

[0004] However, the prior art still has obvious limitations. The Monte Carlo experiment method has low computational efficiency due to relying on a large number of repeated samplings, and it cannot realize the real-time evaluation of impedance or admittance measurement errors, making it difficult to meet the actual engineering requirements; the matrix inversion method does not fully consider the characteristic of the small internal resistance of the measurement device, resulting in the signal-to-noise ratio law at the coupling frequency not being effectively utilized, and the error evaluation process is complex and the accuracy is insufficient; the decoupling method simplifies the frequency coupling effect too much and ignores the error transmission, making it difficult to accurately quantify the coupling influence. These problems restrict the practicability and reliability of impedance or admittance measurement error evaluation. Summary of the Invention

[0005] In view of the technical problems that the existing impedance or admittance measurement error evaluation methods have low calculation efficiency and cannot be evaluated in real time, the matrix inversion method has insufficient utilization of the signal-to-noise ratio of the coupling frequency due to ignoring the internal resistance characteristics of the device and complex processes, and the decoupling method over-simplifies the frequency coupling effect and ignores error transmission, this application provides an impedance / admittance measurement error evaluation method and system. Through noise amplitude probability distribution modeling, construction of an error expression with frequency coupling compensation, quantization of probability integration in the logarithmic coordinate system, and an inverse-decoupling hybrid strategy, the problems of low efficiency, model distortion, and simplification of the coupling effect in traditional methods are solved, and efficient and accurate impedance / admittance measurement error evaluation and disturbance signal optimization in the low internal resistance scenario of the device are realized.

[0006] In a first aspect, this application provides an impedance / admittance measurement error evaluation method, including the following steps: S1. Collect the noise signals of the target device at different frequencies, and calculate the probability distribution of the noise amplitude at each frequency. The noise signals include voltage noise and current noise; S2. Perform a frequency sweep measurement on the target device. By injecting disturbance signals at each frequency, obtain the amplitude of the frequency sweep response signal at each frequency. The frequency sweep response signals include voltage response signals and current response signals; Calculate the probability distribution of the noise-signal ratio at each frequency. The noise-signal ratio is the ratio of the noise amplitude to the amplitude of the corresponding frequency sweep response signal, including the voltage noise-signal ratio and the current noise-signal ratio ; S3. Construct an expression for calculating the measurement relative error through the inverse method or the decoupling method. The measurement relative error includes the admittance measurement relative error and the impedance measurement relative error ; S4. Decompose the expression for calculating the measurement relative error into the numerator and denominator of the expression, and calculate the probability distributions of the modulus of the numerator of the expression and the modulus of the denominator of the expression respectively; S5. Convert the modulus of the numerator of the expression and the modulus of the denominator of the expression to the logarithmic coordinate system, and calculate the probability distribution of the measurement relative error in the logarithmic coordinate system through convolution calculation. The formula is:

[0007] where is the decibel representation of the amplitude of the measurement relative error ; is at the The modulus of the numerator of the expression for an amplitude interval is a function for calculating the probability distribution of the modulus of the numerator of the expression for the th amplitude interval in a logarithmic coordinate system; is a function for calculating the probability distribution of the modulus of the denominator of the expression for the th amplitude interval in a logarithmic coordinate system; is the starting bin index of is the ending bin index of

[0008] It should be further noted that in step S1, the probability distribution of the noise amplitude at each frequency is calculated by the kernel function method, specifically including: segmenting the time series data of the noise signal data and performing discrete Fourier transform, and estimating the probability density of the noise amplitude through kernel density estimation.

[0009] It should be further noted that in step S2, the noise-signal ratio is calculated by the following formula:

[0010] wherein, is the noise amplitude, is the amplitude of the swept-frequency response signal; The formula for the probability within the sample interval is:

[0011] wherein, represents the i-th amplitude interval of represents the average value of in the represents the kernel density of the th amplitude interval in the range from M to N - 1, obtained by fitting the actual noise data through the kernel function method.

[0012] It should be further noted that in step S3, when constructing the measurement relative error expression by the inversion method, the admittance measurement relative error includes the MIMO positive-sequence admittance measurement relative error , the MIMO negative-sequence admittance measurement relative error , the MIMO positive-sequence-negative-sequence coupling admittance measurement relative error , the MIMO negative-sequence-positive-sequence coupling admittance measurement relative error ; Relative error of impedance measurement including the relative error of MIMO positive-sequence impedance measurement , the relative error of MIMO negative-sequence impedance measurement , the relative error of MIMO positive-sequence to negative-sequence coupling impedance measurement , the relative error of MIMO negative-sequence to positive-sequence coupling impedance measurement .

[0013] Among them, MIMO refers to Multi-Input Multi-Output.

[0014] Furthermore, it should be noted that the steps to construct the relative error expression of measurement by the inversion method include: S301. Calculate the frequency coupling degree , including the positive-sequence to negative-sequence coupling degree of admittance , the negative-sequence to positive-sequence coupling degree of admittance , the positive-sequence to negative-sequence coupling degree of impedance , the negative-sequence to positive-sequence coupling degree of impedance ; S302. Judge the frequency coupling degree whether it is lower than the preset threshold. If so, construct the relative error expression of measurement by the inversion method with coupling degree compensation; If not, construct the relative error expression of measurement by the inversion method without compensation.

[0015] Furthermore, it should be noted that the calculation formula of the frequency coupling degree includes:

[0016]

[0017] In the formula, is the negative-sequence current noise amplitude at the negative-sequence coupling frequency ; is the positive-sequence current response signal amplitude at the positive-sequence frequency ; is the positive-sequence current noise amplitude at the positive-sequence coupling frequency ; is the negative-sequence current response signal amplitude at the negative-sequence frequency ; is the negative-sequence voltage noise amplitude at the negative-sequence coupling frequency ; is the positive-sequence frequency amplitude of the positive-sequence voltage response signal under is the positive-sequence coupling frequency amplitude of the positive-sequence voltage response signal under is the negative-sequence frequency amplitude of the negative-sequence voltage response signal under

[0018] Furthermore, it should be noted that the expression of the relative error of the inverse method measurement with coupling degree compensation includes:

[0019]

[0020]

[0021]

[0022]

[0023]

[0024]

[0025]

[0026] In the formula, is the positive-sequence frequency amplitude of the voltage noise under is the positive-sequence coupling frequency amplitude of the voltage noise under is the negative-sequence frequency amplitude of the voltage noise under is the negative-sequence coupling frequency amplitude of the voltage noise under is the positive-sequence frequency amplitude of the current noise under is the positive-sequence coupling frequency amplitude of the current noise under is the negative-sequence frequency amplitude of the current noise under is the negative-sequence coupling frequency amplitude of the current noise under is the positive-sequence frequency Positive-sequence voltage noise-signal ratio under; is the negative-sequence frequency Negative-sequence voltage noise-signal ratio under; is the positive-sequence frequency Positive-sequence current noise-signal ratio under; is the negative-sequence frequency Negative-sequence current noise-signal ratio under.

[0027] It should be further noted that the expression of the relative error of the inverse method measurement without compensation includes:

[0028]

[0029]

[0030]

[0031]

[0032]

[0033]

[0034]

[0035] In the formula, is the positive-sequence coupling frequency Positive-sequence voltage noise-signal ratio under; is the negative-sequence coupling frequency Negative-sequence voltage noise-signal ratio under; is the positive-sequence coupling frequency Positive-sequence current noise-signal ratio under; is the negative-sequence coupling frequency Negative-sequence current noise-signal ratio under; is the theoretical relative error of the SISO positive-sequence admittance on the device side; is the theoretical relative error of the SISO negative-sequence admittance on the device side; is the theoretical relative error of the SISO positive-sequence-negative-sequence coupling admittance on the device side; is the theoretical relative error of the SISO negative-sequence-positive-sequence coupling admittance on the device side; is the theoretical relative error of the SISO positive-sequence impedance on the device side; is the theoretical relative error of the SISO negative-sequence impedance on the device side; is the theoretical relative error of the SISO positive-sequence to negative-sequence coupling impedance on the device side; is the theoretical relative error of the SISO negative-sequence to positive-sequence coupling impedance on the device side.

[0036] Furthermore, it should be noted that 、 、 、 、 、 、 、 The calculation formula is:

[0037]

[0038]

[0039]

[0040] In the formula, The calculation formula is: ; The calculation formula is: ; is the transfer function of the perturbation signal and the response signal when injecting a positive-sequence perturbation. When the perturbation is a series voltage perturbation, is The calculation formula is:

[0041] When the perturbation is a shunt current perturbation, is The calculation formula is:

[0042] Among them, represents the injected positive-sequence perturbation voltage; represents the injected positive-sequence perturbation current; is the transfer function of the perturbation signal and the response signal when injecting a negative-sequence perturbation. When the perturbation is a series voltage perturbation, For , the calculation formula is:

[0043] When the disturbance is a shunt current disturbance, For , the calculation formula is:

[0044] Wherein, represents the injected negative-sequence disturbance voltage; represents the injected negative-sequence disturbance current.

[0045] It should be further noted that in step S3, when constructing the measurement relative error expression by the decoupling method, the measurement relative error of the SISO positive-sequence admittance is , the measurement relative error of the SISO positive-sequence to negative-sequence coupling admittance , the measurement relative error of the SISO negative-sequence admittance , the measurement relative error of the SISO negative-sequence to positive-sequence coupling admittance ; The measurement relative error of the impedance includes the measurement relative error of the SISO positive-sequence impedance , the measurement relative error of the SISO positive-sequence to negative-sequence coupling impedance , the measurement relative error of the SISO negative-sequence impedance , the measurement relative error of the SISO negative-sequence to positive-sequence coupling impedance .

[0046] Wherein, SISO refers to Single-Input Single-Output.

[0047] It should be further noted that the measurement relative error expression constructed by the decoupling method includes:

[0048]

[0049] .

[0050] Further, it should be noted that in step S4, the probability distributions of the numerator modulus value and the denominator modulus value are calculated using numerical integration methods. When there are 2 complex variables involved in the combined calculation in a numerator modulus value or a denominator modulus value, the steps for calculating the probability distribution of the numerator modulus value or the denominator modulus value include: S401. Define the two complex variables as and , let the amplitude distribution range of be , let the amplitude distribution range of be , let the vector and modulus value , calculate the total probability distribution of:

[0051] In the formula, is the conditional probability density function, and the expression is: ; is the probability distribution in the i-th amplitude interval; is the probability distribution in the j-th amplitude interval; I is the indicator function, and the expression is: ; When there are 3 complex variables involved in the combined calculation in a numerator modulus value or a denominator modulus value, first execute step S401 using two complex variables, and use the obtained calculation result as a new complex variable, and execute step S401 with the third complex variable to obtain the probability distribution of the numerator modulus value or the denominator modulus value.

[0052] In the second aspect, the present application provides an impedance / admittance measurement error evaluation system for implementing the above-mentioned impedance / admittance measurement error evaluation method for an integrated energy system, including: A data acquisition and calculation module for collecting noise signals of a target device at different frequencies and calculating the probability distribution of the noise amplitude at each frequency; A frequency sweep measurement module for performing a frequency sweep measurement on the target device to obtain the amplitude of the frequency sweep response signal at each frequency; A noise-signal ratio calculation module for calculating the probability distribution of the noise-signal ratio at each frequency; An error expression construction module for constructing an expression for calculating the measurement relative error by the inversion method or the decoupling method; The modulus probability distribution calculation module is used to decompose the expression for calculating the measurement relative error into the numerator and denominator of the expression, and calculate the probability distributions of the modulus of the numerator and the modulus of the denominator of the expression respectively. and the modulus of the denominator of the expression of the probability distribution; The logarithmic coordinate conversion and result calculation module is used to convert the modulus of the numerator of the expression and the modulus of the denominator of the expression to the logarithmic coordinate system and calculate the probability distribution of the measurement relative error in the logarithmic coordinate system.

[0053] In a third aspect, the present application provides an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. The processor is used to implement the steps of the above impedance / admittance measurement error evaluation method when executing the computer program.

[0054] In a fourth aspect, the present application provides a storage medium with a computer program stored thereon. The computer program, when executed by a processor, implements the steps of the above impedance / admittance measurement error evaluation method.

[0055] It can be seen from the above technical solutions that the present application has the following advantages: 1. By collecting the noise signals of the target device at different frequencies and coupling frequencies, calculating the probability distribution of the noise amplitude based on kernel density estimation, and generating the probability distribution of the noise-signal ratio in combination with the amplitude data of the swept-frequency response signal, the present application can directly use the actual noise data to quickly fit the noise characteristics, realize the accurate modeling of noise interference, avoid the defect of the traditional Monte Carlo experiment method relying on a large number of samplings, significantly improve the evaluation efficiency through the direct calculation of the probability density function, and shift the error evaluation from offline simulation to real-time analysis, providing data support for the dynamic optimization of the disturbance signal design.

[0056] 2. For the scenario where the internal resistance of the measurement device is small and the signal-to-noise ratio of the coupling frequency signal is low, the present application constructs a measurement relative error expression with frequency coupling degree compensation, dynamically correlates the noise-signal ratio with the amplitude of the swept-frequency response signal, accurately quantifies the error contribution, solves the problem of error evaluation distortion caused by the traditional method ignoring the attenuation of the coupling frequency signal, and improves the evaluation reliability in the low signal-to-noise ratio scenario.

[0057] 3. After the measurement relative error expression, the present application decomposes the measurement relative error into the probability distributions of the numerator modulus and the denominator modulus, and calculates the probability distribution of the measurement relative error based on the probability integral in the logarithmic coordinate system, intuitively representing the boundary influence of the noise randomness on the measurement result, providing a quantitative basis for the credibility of the evaluation result, guiding the optimal selection of the amplitude and frequency points of the disturbance signal, and finally realizing high-precision impedance measurement.

[0058] 4. The error expression construction strategy of this application combines the inverse method and the decoupling method, covers the error transmission path, and introduces a frequency coupling degree threshold judgment mechanism to dynamically select the compensation model, effectively solving the problem that the traditional decoupling method ignores the coupling effect. At the same time, it avoids the accuracy degradation of the matrix inversion method in low signal-to-noise ratio scenarios, significantly improving the accuracy of impedance and admittance measurement error evaluation, and providing a reliable basis for optimizing the perturbation signal design and high-precision impedance measurement. Brief Description of the Drawings

[0059] To more clearly illustrate the technical solutions of this application, the drawings required for description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of this application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0060] Figure 1 is a flowchart of the method for evaluating impedance / admittance measurement error in an embodiment of this application.

[0061] Figure 2 is a schematic diagram of the admittance / impedance measurement experimental platform in an embodiment of this application.

[0062] Figure 3 is a simulated noise power density graph in an embodiment of this application.

[0063] Figure 4 is a comparison graph of the theoretical confidence interval calculated in an embodiment of this application and the actual confidence interval obtained by Monte Carlo simulation.

[0064] Figure 5 is the MIMO frequency-coupled sequence impedance in an embodiment of this application Comparison graph of the measured error and confidence level at a frequency of 25 Hz.

[0065] Figure 6 is the MIMO frequency-coupled sequence impedance in an embodiment of this application Comparison graph of the measured error and confidence level at a frequency of 55 Hz.

[0066] Figure 7 is the MIMO frequency-coupled sequence impedance in an embodiment of this application Comparison graph of the measured error and confidence level at a frequency of 70 Hz.

[0067] Figure 8 is the MIMO frequency-coupled sequence impedance in an embodiment of this application Comparison graph of the measured error and confidence level at a frequency of 105 Hz.

[0068] Figure 9is the MIMO frequency coupling sequence impedance in an embodiment of the present application Comparison graph of the measured error and confidence level at a frequency of 205 Hz.

[0069] Figure 10 is the schematic diagram of the frequency sweep and error band of the decoupling method and the inversion method in a noise environment in an embodiment of the present application; Among them, Figure 10 in (a) is the amplitude schematic diagram, Figure 10 in (b) is the phase angle schematic diagram.

[0070] Figure 11 is the schematic block diagram of the evaluation system for impedance / admittance measurement error in an embodiment of the present application.

[0071] Figure 12 is the schematic diagram of the hardware structure of an electronic device in an embodiment of the present application. Detailed implementation manners

[0072] To make the application purpose, features, and advantages of the present application more obvious and understandable, the technical solutions protected by the present application will be clearly and completely described below by using specific embodiments and the accompanying drawings. Obviously, the embodiments described below are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts shall fall within the protection scope of the present application.

[0073] The evaluation method for impedance / admittance measurement error involved in the present application will be described in detail below. For the purpose of illustration rather than limitation, specific details such as specific system structures and technologies are proposed to thoroughly understand the embodiments of the present application. However, those skilled in the art should clearly understand that the present application can also be implemented in other embodiments without these specific details.

[0074] In the evaluation method for impedance / admittance measurement error involved in the present application, the term "including" indicates the existence of the described features, wholes, steps, operations, elements, and / or components, but does not exclude the existence or addition of one or more other features, wholes, steps, operations, elements, components, and / or their combinations. The terms "including", "comprising", "having" and their variants all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0075] The evaluation method for impedance / admittance measurement error provided by the embodiments of the present application is executed by a computer device. Correspondingly, the evaluation system for impedance / admittance measurement error runs in the computer device.

[0076] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present application.

[0077] Figure 1 This is a flowchart of an evaluation method for impedance / admittance measurement error in an embodiment of the present application. Among them, Figure 1 The execution subject can be an evaluation system for impedance / admittance measurement error. According to different requirements, the order of steps in this flowchart can be changed, and some can be omitted.

[0078] As Figure 1 shown, the evaluation method for impedance / admittance measurement error includes: Step S1, collect the noise signals of the target device at different frequencies, and calculate the probability distribution of the noise amplitude at each frequency. The noise signals include voltage noise and current noise.

[0079] By collecting the voltage and current noise signals of the target device at different frequencies and coupling frequencies and calculating their amplitude probability distributions, it provides a multi-dimensional noise characteristic data basis for subsequent error analysis, ensures coverage of the noise interference characteristics of the device under different working conditions, and establishes an accurate data model for quantifying the impact of noise on measurement.

[0080] In some specific embodiments, the probability distribution of the noise amplitude at each frequency is calculated by the kernel function method, specifically including: segmenting the time series data of the noise signal data and performing discrete Fourier transform, and estimating the probability density of the noise amplitude through kernel density estimation.

[0081] By sampling the actual noise data, the probability distribution of the noise amplitude at different frequencies can be statistically obtained. Let the sweep frequency sampling time be , and before the sweep frequency, intercept the time series data with a duration of 、 from the observed data, divide it evenly into segments, and after FFT calculation (i.e., fast discrete Fourier transform), statistically obtain the probability distribution of the amplitude at different frequencies through the kernel function method.

[0082] By performing density estimation on the FFT segmented data through the kernel function method, it can accurately capture the non-Gaussian distribution characteristics of the noise amplitude, overcome the discretization error of traditional histogram statistics, and improve the accuracy and adaptability of the noise probability density estimation.

[0083] Step S2, perform sweep frequency measurement on the target device, and obtain the sweep frequency response signal amplitude at each frequency by injecting perturbation signals at each frequency. The sweep frequency response signals include voltage response signals and current response signals; Calculate the probability distribution of the noise-signal ratio at each frequency. The noise-signal ratio is the ratio of the noise amplitude to the corresponding sweep frequency response signal amplitude, including the voltage noise-signal ratio Sum current noise - signal ratio .

[0084] By combining the amplitude of the swept - frequency response signal and the amplitude of the noise to calculate the probability distribution of the noise - signal ratio at each frequency, an accurate quantitative evaluation of the relationship between the noise and the useful signal energy is achieved, providing key input parameters for subsequent error modeling.

[0085] In some specific embodiments, the noise - signal ratio is calculated by the formula:

[0086] wherein, is the amplitude of the noise, is the amplitude of the swept - frequency response signal; In the sample interval the probability calculation formula is:

[0087] wherein, represents the i - th amplitude interval of; represents in the th amplitude interval average value; represents the kernel density of the th amplitude interval in the range from M to N - 1, obtained by fitting the actual noise data through the kernel function method.

[0088] Among them, the relationship between the amplitude of the swept - frequency response signal and the noise - signal ratio can be expressed as:

[0089] wherein, is the measured signal with superimposed noise. It is not difficult to see that the measurement error of the noise is the reciprocal of the signal - to - noise ratio (SNR) of the signal, that is, the noise - signal ratio (NSR). The NSR of the signal can simultaneously reflect the maximum value of the relative error of the amplitude and the relative error of the phase of the signal: .

[0090] By establishing a probability calculation model of the noise - signal ratio in a discrete interval and combining kernel density to fit the actual noise data, a refined modeling of the probability characteristics of noise interference is achieved, providing a reliable statistical basis for error propagation analysis.

[0091] Step S3, construct the expression for calculating the measurement relative error through the inversion method or the decoupling method of the measurement relative error including the relative error of admittance measurement and the relative error of impedance measurement .

[0092] By constructing the expression of the measurement relative error including two types of parameters, admittance and impedance, it completely covers the core parameter types required for power system stability analysis, and at the same time provides two error modeling paths, the inversion method and the decoupling method, to meet the requirements of different measurement scenarios.

[0093] In some specific embodiments, when constructing the expression of the measurement relative error through the inversion method, the relative error of admittance measurement includes the MIMO positive-sequence admittance measurement relative error , the MIMO negative-sequence admittance measurement relative error , the MIMO positive-sequence-negative-sequence coupling admittance measurement relative error , the MIMO negative-sequence-positive-sequence coupling admittance measurement relative error ; the relative error of impedance measurement includes the MIMO positive-sequence impedance measurement relative error , the MIMO negative-sequence impedance measurement relative error , the MIMO positive-sequence-negative-sequence coupling impedance measurement relative error , the MIMO negative-sequence-positive-sequence coupling impedance measurement relative error .

[0094] The inversion method is mostly used in dq impedance measurement, and this method is also applicable to solving sequence impedance. What the inversion method calculates is the MIMO sequence impedance. Therefore, the relative errors of admittance measurement regarding the inversion method are all the relative errors of sequence admittance measurement or coupling admittance measurement of MIMO, and the same applies to the relative errors of impedance measurement. The MIMO sequence impedance calculated by the inversion method can be converted into dq impedance after frequency shift, so it is called accurate sequence impedance. In the measurement process, the inversion method injects two linearly independent perturbation signals successively to ensure obtaining two groups of linearly independent response signals between voltage and current, and then calculates the impedance by means of matrix inversion.

[0095] By classifying the measurement error types of admittance and impedance, a complete error evaluation system for sequence impedance parameters is established to meet the differential requirements of parameter accuracy for multi-dimensional stability analysis of power electronic equipment.

[0096] In some specific embodiments, the steps of constructing the expression of the measurement relative error through the inversion method include: S301. Calculate the frequency coupling degree , including the positive-sequence-negative-sequence coupling degree of admittance Admittance negative sequence - positive sequence coupling degree Impedance positive sequence - negative sequence coupling degree Impedance negative sequence - positive sequence coupling degree ; S302. Determine the frequency coupling degree Whether it is lower than the preset threshold. If so, construct an inverse method measurement relative error expression with coupling degree compensation; If not, construct an inverse method measurement relative error expression without compensation.

[0097] By introducing a frequency coupling degree threshold judgment mechanism, construct an adaptive error expression generation strategy to avoid over - compensation while ensuring calculation accuracy and achieve intelligent configuration of the measurement error model.

[0098] In some specific embodiments, the calculation formula of the frequency coupling degree includes:

[0099]

[0100] In the formula, is the negative - sequence current noise amplitude at the negative - sequence coupling frequency ; is the positive - sequence current response signal amplitude at the positive - sequence frequency ; is the positive - sequence current noise amplitude at the positive - sequence coupling frequency ; is the negative - sequence current response signal amplitude at the negative - sequence frequency ; is the negative - sequence voltage noise amplitude at the negative - sequence coupling frequency ; is the positive - sequence voltage response signal amplitude at the positive - sequence frequency ; is the positive - sequence voltage response signal amplitude at the positive - sequence coupling frequency ; is the negative - sequence voltage response signal amplitude at the negative - sequence frequency ;

[0101] By defining a calculation formula for the frequency coupling degree based on the ratio of positive and negative sequence components, establish a quantitative correlation model between the coupling characteristics of the equipment and the noise propagation path, providing key characteristic parameters for error compensation.

[0102] In some specific embodiments, the relative error expression of the inverse method measurement with coupling degree compensation includes:

[0103]

[0104]

[0105]

[0106]

[0107]

[0108]

[0109]

[0110] In the formula, is the voltage noise amplitude at the positive sequence frequency ; is the voltage noise amplitude at the positive sequence coupling frequency ; is the voltage noise amplitude at the negative sequence frequency ; is the voltage noise amplitude at the negative sequence coupling frequency ; is the current noise amplitude at the positive sequence frequency ; is the current noise amplitude at the positive sequence coupling frequency ; is the current noise amplitude at the negative sequence frequency ; is the current noise amplitude at the negative sequence coupling frequency ; is the positive sequence voltage noise-signal ratio at the positive sequence frequency ; is the negative sequence voltage noise-signal ratio at the negative sequence frequency ; is the positive sequence current noise-signal ratio at the positive sequence frequency ; is the negative sequence current noise-signal ratio at the negative sequence frequency Negative-sequence current noise-signal ratio under

[0111] By constructing an error expression model with coupling degree compensation, a second-order compensation correction term is introduced while retaining the main error term, significantly improving the error evaluation accuracy under high coupling conditions.

[0112] In some specific embodiments, the relative error expression of the inverse method measurement without compensation includes:

[0113]

[0114]

[0115]

[0116]

[0117]

[0118]

[0119]

[0120] In the formula, is the positive-sequence coupling frequency Positive-sequence voltage noise-signal ratio under is the negative-sequence coupling frequency Negative-sequence voltage noise-signal ratio under is the positive-sequence coupling frequency Positive-sequence current noise-signal ratio under is the negative-sequence coupling frequency Negative-sequence current noise-signal ratio under is the theoretical relative error of the SISO positive-sequence admittance on the device side; is the theoretical relative error of the SISO negative-sequence admittance on the device side; is the theoretical relative error of the SISO positive-sequence-negative-sequence coupling admittance on the device side; is the theoretical relative error of the SISO negative-sequence-positive-sequence coupling admittance on the device side; is the theoretical relative error of the SISO positive-sequence impedance on the device side; is the theoretical relative error of the SISO negative-sequence impedance on the device side; is the theoretical relative error of the SISO forward - reverse coupling impedance on the device side; is the theoretical relative error of the SISO reverse - forward coupling impedance on the device side.

[0121] By establishing a simplified error expression under uncompensated conditions, the balance between calculation efficiency and accuracy is achieved in high - coupling scenarios, providing a lightweight solution for rapid error assessment.

[0122] When the matrix inversion method is used in calculating the calculation result considering noise interference can be written as:

[0123] Therefore, the measurement error when calculating can be written as:

[0124] where S1 and S2 are related to the theoretical error and frequency coupling degree:

[0125] When the internal resistance of the measuring device is small, the relative error of the off - diagonal element of either impedance or admittance approaches 0. Here, it is assumed that the relative error of the off - diagonal element of admittance is close to 0. It can be seen that both S1 and S2 are much less than 1. Therefore, the relevant terms containing S 1 S 2 can be ignored; while , the NSR of 、S 2 is inversely proportional to S1 so the relative error of :

[0126] can be obtained according to the above derivation process , , and the expression of

[0127] Due to the fact that in actual measurement, the signal is masked in noise, so theoretically there is no method to extract the ideal signal in a noise environment. That is, whether it is filtering or multiple - mean processing, it can only reduce the NSR of the signal as much as possible. This means that the NSR in error assessment can only be obtained approximately:

[0128] This approximation is fine when the SNR is not large. However, in actual measurements, it is found that when the frequency coupling is K When it is lower, and <<1, the signal-to-noise ratio at the coupling frequency will be very low. For example, under the series voltage condition, , The amplitude is much smaller than the disturbance signal and other response signals, making it difficult to accurately measure the two types of signals; similarly, under the condition of parallel current, , The amplitude is much smaller than the disturbance signal and other response signals, making it difficult to accurately measure the two types of signals. The low signal-to-noise ratio of the signal at the coupling frequency will affect the accuracy of the final calculation result of the inversion method, causing its measurement error to be even greater than that of the decoupling method. Therefore, this scheme artificially sets the frequency coupling degree K The preset threshold value, when the calculated frequency coupling degree K When the value is lower than the preset threshold, the inversion method with coupling compensation is used to measure the relative error expression to estimate the measurement error caused by the noise.

[0129] In some specific embodiments, , , , , , , , The calculation formula is:

[0130]

[0131]

[0132]

[0133] In the formula, The calculation formula is: ; The calculation formula is: ; is the transfer function between the disturbance signal and the response signal when the positive sequence disturbance is injected. When the disturbance is a series voltage disturbance, for , the calculation formula is:

[0134] When the disturbance is a shunt current disturbance, is , and the calculation formula is:

[0135] where, represents the injected positive-sequence disturbance voltage; represents the injected positive-sequence disturbance current; is the transfer function of the disturbance signal and the response signal when injecting negative-sequence disturbance. When the disturbance is a series voltage disturbance, is , and the calculation formula is:

[0136] When the disturbance is a shunt current disturbance, is , and the calculation formula is:

[0137] where, represents the injected negative-sequence disturbance voltage; represents the injected negative-sequence disturbance current.

[0138] Among them, when it is series positive-sequence voltage / shunt positive-sequence current, and are respectively written as:

[0139] ; where, is the positive-sequence admittance on the device side, ; is the positive-sequence admittance on the grid side; is the positive-sequence impedance on the device side, ; is the positive-sequence impedance on the grid side; Taking the series voltage disturbance as an example, when , , , , and , have the following relationship:

[0140] ; Define the coupling frequency 、 The product of the positive-sequence and negative-sequence voltages and the frequency 、 The ratio of the product of the positive-sequence and negative-sequence voltages is : ; Thus, the theoretical relative error of the positive-sequence admittance Can be written as: ; Similarly, define To represent the coupling frequency 、 The product of the positive-sequence and negative-sequence currents and the frequency 、 The ratio of the product of the positive-sequence and negative-sequence currents: ; Then, the relative error of the positive-sequence impedance Can be evaluated as follows:

[0141]

[0142] Replacing all subscripts p in the above formula with subscript n, the error evaluation of the negative-sequence admittance and impedance can be performed.

[0143] Since the deviation between the approximate value and the actual value in the approximate relationship of the above formula is extremely small, for the convenience of calculation, the approximate equal sign is regarded as an equal sign in the calculation of this scheme.

[0144] By constructing a mathematical relationship model between the theoretical relative error and the parameters of power grid equipment, the abstract error quantity is transformed into a measurable combination of physical quantities, realizing the accurate positioning and quantitative analysis of the error source.

[0144] In some specific embodiments, when constructing the measurement relative error expression by the decoupling method, the measurement relative error of the admittance Includes the measurement relative error of the SISO positive-sequence admittance 、The measurement relative error of the SISO positive-sequence to negative-sequence coupling admittance 、The measurement relative error of the SISO negative-sequence admittance 、The measurement relative error of the SISO negative-sequence to positive-sequence coupling admittance 、The measurement relative error of the SISO negative-sequence admittance 、The measurement relative error of the SISO negative-sequence to positive-sequence coupling admittance 、The measurement relative error of the SISO negative-sequence to positive-sequence coupling admittance 、The measurement relative error of the SISO negative-sequence to positive-sequence coupling admittance ; The measurement relative error of the impedance includes the measurement relative error of the SISO positive-sequence impedance 、The measurement relative error of the SISO positive-sequence impedance , Measurement relative error of SISO forward - reverse sequence coupling impedance , Measurement relative error of SISO negative - sequence impedance , Measurement relative error of SISO negative - forward sequence coupling impedance .

[0145] Among them, the decoupling method decouples the 2×2 sequence admittance matrix into 2 SISO admittances and . Therefore, the measurement relative error of the admittance regarding the decoupling method is the measurement relative error of the sequence admittance or the coupling admittance of SISO, and the same applies to the impedance measurement relative error. Since the decoupled admittance includes the source - side admittance, some people call it the sequence admittance considering the power grid.

[0146] By expanding the error evaluation object of the decoupling method to the positive and negative sequence coupling parameters, a complete error evaluation system of the decoupling method is established to improve the analytical ability of the measurement error of complex coupling systems.

[0147] In some specific embodiments, the measurement relative error expression constructed by the decoupling method includes:

[0148]

[0149] .

[0150] By establishing an independent calculation model for the errors of each parameter of the decoupling method, parallel calculation of multi - parameter errors is realized, significantly improving the calculation efficiency and feasibility of the error evaluation of the decoupling method.

[0151] Step S4, decompose the expression for calculating the measurement relative error into the numerator and denominator of the expression, and calculate the probability distributions of the modulus of the numerator of the expression and the modulus of the denominator of the expression respectively.

[0152] By decomposing the error expression into the modulus of the numerator and the modulus of the denominator and independently calculating their probability distributions, the statistical characteristics of the error - forming elements are effectively separated, establishing an operable mathematical processing framework for subsequent error synthesis.

[0153] In some specific embodiments, the numerical integration method is used to calculate the probability distributions of the modulus of the numerator and the modulus of the denominator. When there are 2 complex variables participating in the combined calculation in a modulus of a numerator or a modulus of a denominator, the steps for calculating the probability distribution of the modulus of the numerator or the modulus of the denominator include: S401. Define the two complex variables as and​​​ , let have an amplitude distribution range of , let have an amplitude distribution range of , let the vector and modulus , calculate 's total probability distribution:

[0154] In the formula, is the conditional probability density function, and the expression is: ; is 's probability distribution in the i-th amplitude interval; is 's probability distribution in the j-th amplitude interval; I is the indicator function, and the expression is: ; When there are 3 complex variables participating in the combined calculation in a molecular modulus or a denominator modulus, first use two complex variables to execute step S401, and use the obtained calculation result as a new complex variable, and execute step S401 with the third complex variable to obtain the probability distribution of the molecular modulus or the denominator modulus.

[0155] By constructing a probability synthesis algorithm for the combined modulus of complex variables, the calculation problem of the joint distribution of multiple variables is overcome, providing a feasible numerical analysis method for the complex error transfer process.

[0156] S5. Convert the molecular modulus of the expression and the denominator modulus of the expression to the logarithmic coordinate system, and calculate the probability distribution of the measurement relative error in the logarithmic coordinate system through convolution calculation. The formula is:

[0157] In the formula, is the decibel representation of the amplitude of the measurement relative error ; is the molecular modulus of the expression in the -th amplitude interval, is the function for calculating the probability distribution of the molecular modulus of the expression in the logarithmic coordinate system in the -th amplitude interval; is the function for calculating the probability distribution of the denominator modulus of the expression in the logarithmic coordinate system in the -th amplitude interval; is the starting bin index of is the ending bin index of

[0158] By converting the modulus value to the logarithmic coordinate system and constructing a probability distribution synthesis formula, the linearization process of the complex error propagation process is realized, and the computational complexity of the multi-dimensional probability distribution synthesis is significantly reduced.

[0159] In a specific embodiment, the method for evaluating the impedance / admittance measurement error includes: Step S1: Collect the noise signals of the target device at different frequencies. The noise signals include voltage noise and current noise; Calculate the probability distribution of the noise amplitude at each frequency by the kernel function method. Specifically, it includes: segmenting the time series data of the noise signal data and performing discrete Fourier transform, and estimating the probability density of the noise amplitude through kernel density estimation.

[0160] Step S2: Perform a swept-frequency measurement on the target device. By injecting perturbation signals at each frequency, obtain the amplitudes of the swept-frequency response signals at each frequency. The swept-frequency response signals include voltage response signals and current response signals; Calculate the probability distribution of the noise-signal ratio at each frequency. The noise-signal ratio is the ratio of the noise amplitude to the amplitude of the corresponding swept-frequency response signal, including the voltage noise-signal ratio and the current noise-signal ratio . The calculation formula of the noise-signal ratio is:

[0161] In the formula, is the noise amplitude, is the amplitude of the swept-frequency response signal; The calculation formula of the probability within the sample interval is:

[0162] In the formula, represents the i-th amplitude interval of represents the average value of in the i-th amplitude interval; represents the kernel density of the -th amplitude interval in the range from M to N - 1, which is obtained by fitting the actual noise data through the kernel function method.

[0163] Step S3. Construct the expression for calculating the measurement relative error by the inversion method or the decoupling method The measurement relative error includes the relative error of admittance measurement and the relative error of impedance measurement ; When constructing the expression for the measurement relative error by the inversion method, the relative error of admittance measurement includes the relative error of MIMO positive-sequence admittance measurement , the relative error of MIMO negative-sequence admittance measurement , the relative error of MIMO positive-sequence to negative-sequence coupled admittance measurement , the relative error of MIMO negative-sequence to positive-sequence coupled admittance measurement : The relative error of impedance measurement includes the relative error of MIMO positive-sequence impedance measurement , the relative error of MIMO negative-sequence impedance measurement , the relative error of MIMO positive-sequence to negative-sequence coupled impedance measurement , the relative error of MIMO negative-sequence to positive-sequence coupled impedance measurement ; The steps of constructing the expression for the measurement relative error by the inversion method include: S301. Calculate the frequency coupling degree , including the positive-sequence to negative-sequence coupling degree of admittance , the negative-sequence to positive-sequence coupling degree of admittance , the positive-sequence to negative-sequence coupling degree of impedance , the negative-sequence to positive-sequence coupling degree of impedance ; S302. Judge whether the frequency coupling degree is lower than the preset threshold. If so, construct the expression for the measurement relative error by the inversion method with coupling degree compensation; If not, construct the expression for the measurement relative error by the inversion method without compensation.

[0164] Among them, the calculation formula of the frequency coupling degree includes:

[0165]

[0166] In the formula, is the amplitude of the negative-sequence current noise at the negative-sequence coupling frequency ; is the amplitude of the positive-sequence current response signal at the positive-sequence frequency ; is the positive-sequence coupled frequency and is the amplitude of the positive-sequence current noise under is the negative-sequence frequency and is the amplitude of the negative-sequence current response signal under is the negative-sequence coupled frequency and is the amplitude of the negative-sequence voltage noise under is the positive-sequence frequency and is the amplitude of the positive-sequence voltage response signal under is the positive-sequence coupled frequency and is the amplitude of the positive-sequence voltage response signal under is the negative-sequence frequency and is the amplitude of the negative-sequence voltage response signal under The expression of the relative error measured by the inverse method with coupling degree compensation includes:

[0167]

[0168]

[0169]

[0170]

[0171]

[0172]

[0173]

[0174] wherein, is the positive-sequence frequency and is the amplitude of the voltage noise under is the positive-sequence coupled frequency and is the amplitude of the voltage noise under is the negative-sequence frequency and is the amplitude of the voltage noise under is the negative-sequence coupled frequency and is the amplitude of the voltage noise under is the positive-sequence frequency and is the amplitude of the current noise under is the positive-sequence coupled frequency and is the amplitude of the current noise under The current noise amplitude at negative sequence frequency ; The current noise amplitude at negative sequence coupling frequency ; The positive sequence voltage noise-signal ratio at positive sequence frequency ; The negative sequence voltage noise-signal ratio at negative sequence frequency ; The positive sequence current noise-signal ratio at positive sequence frequency ; The negative sequence current noise-signal ratio at negative sequence frequency ; The measurement relative error expression of the inverse method without compensation includes:

[0175]

[0176]

[0177]

[0178]

[0179]

[0180]

[0181]

[0182] Wherein, The positive sequence voltage noise-signal ratio at positive sequence coupling frequency ; The negative sequence voltage noise-signal ratio at negative sequence coupling frequency ; The positive sequence current noise-signal ratio at positive sequence coupling frequency ; The negative sequence current noise-signal ratio at negative sequence coupling frequency ; Is the theoretical relative error of the SISO positive sequence admittance on the equipment side; is the theoretical relative error of the SISO negative-sequence admittance on the device side; is the theoretical relative error of the SISO positive-sequence to negative-sequence coupling admittance on the device side; is the theoretical relative error of the SISO negative-sequence to positive-sequence coupling admittance on the device side; is the theoretical relative error of the SISO positive-sequence impedance on the device side; is the theoretical relative error of the SISO negative-sequence impedance on the device side; is the theoretical relative error of the SISO positive-sequence to negative-sequence coupling impedance on the device side; is the theoretical relative error of the SISO negative-sequence to positive-sequence coupling impedance on the device side; 、 、 、 、 、 、 、 The calculation formula of

[0183]

[0184]

[0185]

[0186] In the formula, The calculation formula of ; The calculation formula of ; is the transfer function of the perturbation signal and the response signal when injecting a positive-sequence perturbation. When the perturbation is a series voltage perturbation, is The calculation formula is:

[0187] When the perturbation is a shunt current perturbation, is The calculation formula is:

[0188] Among them, represents the positive-sequence perturbation voltage injected; represents the positive-sequence perturbation current injected; is the transfer function of the perturbation signal and the response signal when injecting negative-sequence perturbation. When the perturbation is a series voltage perturbation, is , and the calculation formula is:

[0189] When the perturbation is a shunt current perturbation, is , and the calculation formula is:

[0190] Among them, represents the negative-sequence perturbation voltage injected; represents the negative-sequence perturbation current injected.

[0191] When constructing the measurement relative error expression by the decoupling method, the measurement relative error of admittance includes the measurement relative error of SISO positive-sequence admittance , the measurement relative error of SISO positive-sequence to negative-sequence coupling admittance , the measurement relative error of SISO negative-sequence admittance , the measurement relative error of SISO negative-sequence to positive-sequence coupling admittance ; The measurement relative error of impedance includes the measurement relative error of SISO positive-sequence impedance , the measurement relative error of SISO positive-sequence to negative-sequence coupling impedance , the measurement relative error of SISO negative-sequence impedance , the measurement relative error of SISO negative-sequence to positive-sequence coupling impedance ; The measurement relative error expression constructed by the decoupling method includes:

[0192]

[0193] .

[0194] ​​​​​​​​Step S4: Decompose the expression for calculating the measurement relative error into the numerator and denominator of the expression, and calculate the modulus values of the numerator and denominator of the expression respectively. and the modulus value of the denominator of the expression The probability distributions of the modulus values of the numerator and denominator of the expression are calculated. When there are two complex variables involved in the combined calculation in the modulus value of a numerator or denominator, the steps for calculating the probability distribution of the modulus value of the numerator or denominator include: S401. Define the two complex variables as and respectively. Let have an amplitude distribution range of Let have an amplitude distribution range of Let the vector sum and modulus value Calculate the total probability distribution of as follows:

[0195] In the formula, is the conditional probability density function, and the expression is: ; is the probability distribution in the i-th amplitude interval; is the probability distribution in the j-th amplitude interval; I is the indicator function, and the expression is: ; When there are three complex variables involved in the combined calculation in the modulus value of a numerator or denominator, first perform step S401 using two complex variables, and use the calculation result as a new complex variable. Then perform step S401 with the third complex variable to obtain the probability distribution of the modulus value of the numerator or denominator.

[0196] Step S5: Transform the modulus value of the numerator of the expression and the modulus value of the denominator of the expression to the logarithmic coordinate system, and calculate the probability distribution of the measurement relative error in the logarithmic coordinate system through convolution calculation. The formula is:

[0197] In the formula, is the decibel representation of the amplitude of the measurement relative error ; is the modulus value of the numerator of the expression in the -th amplitude interval, is for calculating in the Function of the probability distribution of the magnitude of the numerator of the expression in a logarithmic coordinate system for each amplitude interval; To calculate at the Function of the probability distribution of the magnitude of the denominator of the expression in a logarithmic coordinate system for each amplitude interval; For Starting bin index of For Ending bin index of

[0198] Using the method of this embodiment to conduct an impedance / admittance measurement error evaluation experiment, injecting a series voltage perturbation into the admittance / impedance measurement experimental platform. The schematic diagram of the admittance / impedance measurement experimental platform is as shown in Figure 2 As shown, the simulated noise power density graph generated from a section of noise data intercepted in actual measurement is as shown in Figure 3 As shown.

[0199] From Figure 3 It can be seen that the noise shows an obvious pink characteristic in the low-frequency band, that is, as the frequency increases, the power density of the noise decays.

[0200] Using the data measured in step 1-2 of this embodiment for Monte Carlo simulation, the number of Monte Carlo simulation times is 10 5 times, obtaining the actual confidence interval, and comparing it with the theoretical confidence interval calculated in this embodiment. The comparison graph is as shown in Figure 4 As shown; From Figure 4 It can be seen that although the number of Monte Carlo simulation times is 10 5 times, its waveform still has a relatively obvious serrated feeling, while the theoretical probability distribution calculation method adopted in this embodiment (as shown by the red line) can more accurately reflect the probability distribution.

[0201] The measured error and confidence level comparison graph of the MIMO frequency coupling sequence impedance calculated in this embodiment at each frequency is as shown in As shown in Figures 5 - 9 As shown; Figures 5 - 9 The blue circular line in Figures 5 - 9 represents the modulus of the measurement relative error caused by noise in 100 actual measurements, while the red lines respectively represent the predicted values of the modulus of the measurement relative error with confidence levels of 90%, 95% and 99%. From

[0202] In this embodiment, the frequency sweep and error band schematic diagrams of the decoupling method and the inversion method in a noise environment are as shown in Figure 10 As shown, Figure 10In (a), it is the amplitude schematic diagram, and in (b), it is the phase angle schematic diagram; Figure 10 In it, the red line is the MIMO frequency coupling sequence impedance calculated by the inverse method , and the black dashed line is the SISO frequency coupling sequence impedance calculated by the decoupling method ; the light pink band is the error band of the inverse method, and the light purple is the error band of the decoupling method; the blue dots are the measured values of the inverse method in a noise environment, and the green triangles are the measured values of the decoupling method in a noise environment. It can be seen from Figure 10 that as the frequency increases, the error band of the inverse method will be greater than that of the decoupling method, indicating that the measurement error of the inverse method will be greater than that of the decoupling method under certain circumstances.

[0203] The following is an embodiment of the impedance / admittance measurement error evaluation system provided by the present disclosure. This impedance / admittance measurement error evaluation system and the impedance / admittance measurement error evaluation methods of the above embodiments belong to the same inventive concept. For the details not described in detail in the embodiment of the impedance / admittance measurement error evaluation system, reference can be made to the embodiments of the impedance / admittance measurement error evaluation method.

[0204] Now, the mobile terminals implementing various embodiments of the present application will be described with reference to the accompanying drawings. In the following description, suffixes such as "module", "component", or "unit" used to represent elements are only for the convenience of description of the embodiments of the present application, and they have no specific meaning in themselves. Therefore, "module" and "component" can be used interchangeably.

[0205] As Figure 11 shown, the impedance / admittance measurement error evaluation system includes: A data acquisition and calculation module, configured to acquire the noise signals of the target device at different frequencies and calculate the probability distribution of the noise amplitude at each frequency; A frequency sweep measurement module, configured to perform a frequency sweep measurement on the target device to obtain the amplitude of the frequency sweep response signal at each frequency; A noise-signal ratio calculation module, configured to calculate the probability distribution of the noise-signal ratio at each frequency; An error expression construction module, configured to construct an expression for calculating the measurement relative error by the inverse method or the decoupling method; A modulus probability distribution calculation module, configured to decompose the expression for calculating the measurement relative error into the numerator and denominator of the expression, and calculate the probability distribution of the modulus of the numerator of the expression and the probability distribution of the modulus of the denominator of the expression; Modulus value of the denominator of the sum expression Convert to the logarithmic coordinate system and calculate the probability distribution of the measurement relative error in the logarithmic coordinate system.

[0206] The impedance / admittance measurement error evaluation system of this embodiment is used to implement the impedance / admittance measurement error evaluation method.

[0207] This application also provides an electronic device for implementing each embodiment of this application. The electronic device includes a memory, a processor, and a computer program stored on the memory and executable on the processor.

[0208] Those skilled in the art can understand that the structure of the electronic device involved in the embodiments of this application does not constitute a limitation on the electronic device. The electronic device may include more or fewer components than shown in the figure, or combine some components, or have different component arrangements.

[0209] Figure 12 Schematic diagram of the hardware structure of an electronic device for implementing each embodiment of this application.

[0210] The electronic device includes, but is not limited to, components such as a processor and a memory. Those skilled in the art can understand that the structure of the electronic device involved in the embodiments of this application does not constitute a limitation on the electronic device. The electronic device may include more or fewer components than shown in the figure, or combine some components, or have different component arrangements.

[0211] This application also provides a storage medium. In the storage medium, there is a program product capable of implementing the impedance / admittance measurement error evaluation method. In some possible implementation manners, each aspect of this disclosure can also be implemented in the form of a program product, which includes program code. When the program product runs on a terminal device, the program code is used to cause the terminal device to execute the steps according to various exemplary embodiments of this disclosure described in the "Exemplary Method" section above of this specification.

[0212] The storage medium can adopt any combination of one or more readable media. The readable media can be a readable signal medium or a readable storage medium. The readable storage medium can be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device, or component, or any combination of the above.

[0213] The foregoing description of the disclosed embodiments enables those skilled in the art to practice or use the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for evaluating impedance / admittance measurement error, characterized in that, Including: S1. Collect the noise signals of the target device at different frequencies, and calculate the probability distribution of the noise amplitude at each frequency. The noise signals include voltage noise and current noise; S2. Perform a sweep frequency measurement on the target device. By injecting disturbance signals at each frequency, obtain the amplitude of the sweep frequency response signal at each frequency. The sweep frequency response signal includes a voltage response signal and a current response signal; Calculate the noise-signal ratio at each frequency of the probability distribution, where the noise-signal ratio is the ratio of the noise amplitude to the amplitude of the corresponding swept-frequency response signal, including the voltage noise-signal ratio and the current noise-signal ratio ; S3. Construct the expression for calculating the measurement relative error by the inversion method or the decoupling method. The measurement relative error includes the relative error of admittance measurement and the relative error of impedance measurement ; ; S4. Decompose the expression for calculating the relative error of measurement into the numerator and denominator of the expression, and calculate the probability distributions of the modulus of the numerator and the modulus of the denominator of the expression respectively. and the modulus of the denominator of the expression respectively. S5. Modulus value of the numerator of the expression and modulus value of the denominator of the expression are transformed into the logarithmic coordinate system. The calculation of the probability distribution of the measurement relative error in the logarithmic coordinate system is realized through convolution calculation. The formula is as follows: In the formula, is the measurement relative error and is the decibel representation of the amplitude; For the modulus of the numerator of the expression in the th amplitude interval, is a function for calculating the probability distribution of the modulus of the numerator of the expression in the th amplitude interval in the logarithmic coordinate system; To calculate the function of the probability distribution of the modulus of the denominator of the expression in the th amplitude interval in the logarithmic coordinate system; is the starting bin index of is the ending bin index of 2. The evaluation method according to claim 1, wherein In step S2, the noise-signal ratio is calculated by the formula: Wherein, is the noise amplitude, is the amplitude of the swept-frequency response signal; In the sample interval The calculation formula for the probability is as follows: In the formula, represents the i th amplitude interval; represent at the average value of the Indicates M to N-1 the kernel density of the th amplitude interval in the range, which is obtained by fitting the actual noise data through the kernel function method.

3. The evaluation method according to claim 1, characterized in that, In step S3, when constructing the measurement relative error expression by the inverse method, the relative error of admittance measurement includes the relative error of MIMO positive-sequence admittance measurement , the relative error of MIMO negative-sequence admittance measurement , the relative error of MIMO positive-sequence-negative-sequence coupling admittance measurement , and the relative error of MIMO negative-sequence-positive-sequence coupling admittance measurement ; Relative error of impedance measurement including relative error of MIMO positive-sequence impedance measurement , relative error of MIMO negative-sequence impedance measurement , relative error of MIMO positive-sequence to negative-sequence coupling impedance measurement , relative error of MIMO negative-sequence to positive-sequence coupling impedance measurement .

4. The evaluation method according to claim 3, wherein The steps of constructing the measurement relative error expression by the inversion method include: S301. Calculate the frequency coupling degree , including the admittance positive-sequence to negative-sequence coupling degree , the admittance negative-sequence to positive-sequence coupling degree , the impedance positive-sequence to negative-sequence coupling degree , the impedance negative-sequence to positive-sequence coupling degree ; S302. Determine the frequency coupling degree Whether it is lower than a preset threshold. If so, construct an expression for measuring the relative error of the inverse method with coupling degree compensation; If not, construct an uncompensated measurement relative error expression by the inversion method.

5. The evaluation method according to claim 4, wherein The measurement relative error expression of the inversion method with coupling degree compensation includes: In the formula, is the voltage noise amplitude at the positive-sequence frequency ; is the voltage noise amplitude under the positive sequence coupling frequency ; is the negative-sequence frequency voltage noise amplitude under; is the negative-sequence coupling frequency the voltage noise amplitude under; is the current noise amplitude under the positive sequence frequency ; is the current noise amplitude under the positive sequence coupling frequency ; is the negative sequence frequency under the current noise amplitude; is the negative-sequence coupling frequency the current noise amplitude under; is the positive-sequence frequency the positive-sequence voltage noise-signal ratio under; is the negative-sequence frequency negative-sequence voltage noise-signal ratio under; is the positive-sequence frequency positive-sequence current noise-signal ratio under; is the negative sequence frequency negative sequence current noise-signal ratio under 6. The evaluation method according to claim 4, wherein The measurement relative error expression of the uncompensated inversion method includes: In the formula, is the positive-sequence voltage noise-signal ratio under the positive-sequence coupling frequency; is the negative-sequence coupling frequency the negative-sequence voltage noise-signal ratio under; is the positive-sequence coupled frequency positive-sequence current noise-signal ratio under; Negative sequence coupling frequency Negative sequence current noise-signal ratio under is the theoretical relative error of the SISO forward admittance on the device side; is the theoretical relative error of the SISO negative-sequence admittance on the device side; is the theoretical relative error of the SISO forward - reverse sequence coupling admittance on the device side; is the theoretical relative error of the SISO negative-sequence to positive-sequence coupling admittance on the device side; is the theoretical relative error of the SISO forward impedance on the device side; is the theoretical relative error of the SISO negative-sequence impedance on the device side; is the theoretical relative error of the SISO forward - reverse coupling impedance on the device side; is the theoretical relative error of the SISO negative-sequence to positive-sequence coupling impedance on the device side.

7. The evaluation method according to claim 1, characterized in that In step S3, when constructing the measurement relative error expression by the decoupling method, the admittance measurement relative error Including SISO positive sequence admittance The relative error of the measurement , SISO positive-negative sequence coupling admittance The relative error of the measurement , SISO negative sequence admittance The relative error of the measurement , SISO negative-sequence-positive-sequence coupling admittance The relative error of the measurement ; The relative error of impedance measurement includes the relative error of SISO positive-sequence impedance of measurement , the relative error of SISO positive-sequence-negative-sequence coupling impedance of measurement , the relative error of SISO negative-sequence impedance of measurement , the relative error of SISO negative-sequence-positive-sequence coupling impedance of measurement .

8. The evaluation method according to claim 7, wherein The measurement relative error expression constructed by the decoupling method includes: 。 9. The evaluation method according to claim 1, wherein Step S4 uses a numerical integration method to calculate the probability distribution of the molecular modulus value and the denominator modulus value. When there are 2 complex variables participating in the combined calculation in a molecular modulus value or a denominator modulus value, the steps of calculating the probability distribution of the molecular modulus value or the denominator modulus value include: S401. Define two complex variables as and . Let the amplitude distribution range of be . Let the amplitude distribution range of be . Let the vector and the modulus . Calculate the total probability distribution of : wherein, is the conditional probability density function, and the expression thereof is: ； is the probability distribution in the i-th amplitude interval; is the probability distribution in the j-th amplitude interval; I is an indicator function, and the expression is: ； When there are 3 complex variables participating in the combined calculation in a molecular modulus value or a denominator modulus value, first use two complex variables to execute step S401 to obtain the calculation result as a new complex variable, and then execute step S401 with the third complex variable to obtain the probability distribution of the molecular modulus value or the denominator modulus value.

10. An evaluation system for impedance / admittance measurement error, characterized in that, For implementing the evaluation method as described in any one of claims 1-9, including: A data acquisition and calculation module for collecting the noise signals of the target device at different frequencies and calculating the probability distribution of the noise amplitude at each frequency; A sweep frequency measurement module for performing a sweep frequency measurement on the target device to obtain the amplitude of the sweep frequency response signal at each frequency; A noise-signal ratio calculation module, which is used to calculate the noise-signal ratio at each frequency of the probability distribution; An error expression construction module, which is used to construct an expression for calculating the relative measurement error by the inversion method or the decoupling method ; Modulus probability distribution calculation module, which is used to decompose the expression for calculating the measurement relative error into the numerator and denominator of the expression, and calculate the probability distributions of the modulus of the numerator of the expression and the modulus of the denominator of the expression respectively; The logarithmic coordinate conversion and result calculation module is used to convert the modulus of the numerator of the expression and the modulus of the denominator of the expression to the logarithmic coordinate system and calculate the probability distribution of the measurement relative error in the logarithmic coordinate system.

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