A method and system for evaluating impedance / admittance measurement errors

Abstract

The present application relates to the technical field of impedance / admittance measurement error assessment, and specifically to an impedance / admittance measurement error assessment method and system, including: collecting a noise signal from a target device and calculating the probability distribution of the noise amplitude; performing a swept-frequency measurement on the target device, injecting a disturbance signal at each frequency to obtain the swept-frequency response signal amplitude at each frequency, and calculating the probability distribution of the noise-to-signal ratio #imgabs0# at each frequency; constructing an expression for calculating the measurement relative error #imgabs1# through an inversion method or a decoupling method; decomposing the expression for calculating the measurement relative error into a numerator and a denominator, and calculating the probability distributions of the numerator modulus #imgabs2# and the denominator modulus #imgabs3#, respectively; converting the numerator modulus #imgabs4# and the denominator modulus #imgabs5# to a logarithmic coordinate system, and calculating the probability distribution of the measurement relative error in the logarithmic coordinate system. This application can achieve efficient and accurate measurement error assessment and disturbance signal optimization in low-internal-resistance device scenarios.

Description

Technical Field

[0001] The present application relates to the technical field of impedance / admittance measurement error evaluation, and in particular to an impedance / admittance measurement error evaluation method and system. Background Art

[0002] With the rapid development of renewable energy generation, the penetration rate of power electronics equipment in power systems has increased significantly, and system stability issues have become increasingly prominent. The impedance method, a mainstream approach for analyzing the stability of power electronics systems, relies on obtaining the impedance characteristics of the device through swept-frequency measurement. However, in actual measurements, noise interference directly affects the accuracy of impedance measurements. This is especially true in multi-frequency injection scenarios, where the energy dispersion of the disturbance signal leads to a reduced signal-to-noise ratio, further exacerbating the impact of noise on measurement results. Quantifying and evaluating the measurement errors caused by noise has become a key challenge in improving the reliability of the impedance method.

[0003] In existing technologies, sequence impedance calculations are primarily performed using decoupling, improved decoupling, and matrix inversion methods to address noise-induced measurement errors. The decoupling method decouples the sequence admittance matrix by sequentially injecting positive and negative sequence disturbance signals. The improved decoupling method adds subdiagonal element calculations to improve accuracy, while the matrix inversion method constructs the admittance matrix by injecting two linearly independent disturbance signals. Furthermore, Monte Carlo experiments are used to assess error confidence, simulating the effects of noise through large numbers of random samples. These methods attempt to address noise interference from different perspectives and have achieved some success in specific scenarios.

[0004] However, existing technologies still have significant limitations. The Monte Carlo experiment method relies on a large number of repeated sampling, resulting in low computational efficiency. It cannot achieve real-time evaluation of impedance or admittance measurement errors, making it difficult to meet actual engineering needs. The matrix inversion method does not fully consider the low 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 assessment process is complex and lacks accuracy. The decoupling method oversimplifies the frequency coupling effect, ignores error transmission, and has difficulty in accurately quantifying the coupling impact. These problems restrict the practicality and reliability of impedance or admittance measurement error assessment. Summary of the Invention

[0005] In response to the technical problems of low computational efficiency and inability to conduct real-time evaluation in existing impedance or admittance measurement error evaluation methods, the matrix inversion method ignores the internal resistance characteristics of the device, resulting in insufficient utilization of the coupling frequency signal-to-noise ratio and complex processes, and the decoupling method oversimplifies the frequency coupling effect and ignores error transmission, the present application provides an impedance / admittance measurement error evaluation method and system. Through noise amplitude probability distribution modeling, error expression construction for frequency coupling compensation, logarithmic coordinate system probability integral quantization and inversion-decoupling hybrid strategy, the problems of low efficiency, model distortion and coupling effect simplification of traditional methods are solved, and efficient and accurate impedance / admittance measurement error evaluation and disturbance signal optimization are achieved in low internal resistance scenarios of the device.

[0006] In a first aspect, the present application provides a method for evaluating impedance / admittance measurement errors, comprising the following steps:

[0007] S1. Collect noise signals from the target device at different frequencies and calculate the probability distribution of the noise amplitude at each frequency. The noise signal includes voltage noise and current noise.

[0008] S2. Perform a frequency sweep measurement on the target device by injecting a disturbance signal at each frequency to obtain the amplitude of the frequency sweep response signal at each frequency. The frequency sweep response signal includes a voltage response signal and a current response signal.

[0009] Calculate the noise-to-signal ratio at each frequency The probability distribution of the noise-signal ratio is the ratio of the noise amplitude to the corresponding swept frequency response signal amplitude, including the voltage noise-signal ratio and current noise-to-signal ratio ;

[0010] S3. Calculate the relative measurement error by inversion method or decoupling method The expression of measurement relative error Including the relative error of admittance measurement and impedance measurement relative error ;

[0011] S4. Decompose the expression for calculating the relative measurement error into the numerator and denominator, and calculate the modulus of the numerator and denominator respectively. Sum expression denominator modulo value The probability distribution of

[0012] S5. Modulate the expression numerator Sum expression denominator modulo value Convert to the logarithmic coordinate system and calculate the probability distribution of the relative error in the logarithmic coordinate system through convolution calculation. The formula is:

[0013]

[0014] Where, The relative error of the measurement Amplitude is expressed in decibels;

[0015] For the The numerator modulus of the expression for the amplitude interval is, To calculate the The expression of the amplitude interval is a function of the probability distribution of the molecular modulus value in the logarithmic coordinate system;

[0016] To calculate the The function of the probability distribution of the denominator modulus of the expression of the amplitude interval in the logarithmic coordinate system;

[0017] for The starting bin index of for The ending bin index.

[0018] It should be further explained that step S1 calculates the probability distribution of the noise amplitude at each frequency 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 statistical noise amplitude by kernel density estimation.

[0019] It should be further explained that in step S2, the noise-signal ratio The calculation formula is:

[0020]

[0021] Where, is the noise amplitude, is the amplitude of the swept frequency response signal;

[0022] In the sample interval The calculation formula for the internal probability is:

[0023]

[0024] Where, express The i-th amplitude interval of ;

[0025] express In the The average value of the amplitude interval;

[0026] Indicates the number of The kernel density of the amplitude interval is obtained by fitting the actual noise data using the kernel function method.

[0027] It should be further explained that in step S3, when constructing the measurement relative error expression by the inversion method, the admittance measurement relative error Including MIMO positive sequence admittance measurement relative error , MIMO negative sequence admittance measurement relative error , MIMO positive-sequence-negative-sequence coupled admittance measurement relative error , MIMO negative-sequence-positive sequence coupled admittance measurement relative error ;

[0028] Impedance measurement relative error Including MIMO positive sequence impedance measurement relative error , MIMO negative sequence impedance measurement relative error , MIMO positive-sequence-negative-sequence coupling impedance measurement relative error , MIMO negative-sequence-positive sequence coupling impedance measurement relative error .

[0029] Among them, MIMO refers to Multiple-Input Multi-Output (Multi-Input Multi-Output).

[0030] It should be further explained that the steps of constructing the measurement relative error expression by the inversion method include:

[0031] S301. Calculate frequency coupling , including the positive-sequence-negative-sequence coupling of admittance , Admittance negative sequence-positive sequence coupling , Impedance positive sequence-negative sequence coupling , Impedance negative sequence-positive sequence coupling ;

[0032] S302. Determine frequency coupling Is it lower than a preset threshold? If so, construct an inverse method measurement relative error expression including coupling degree compensation;

[0033] If not, then construct an uncompensated inversion method measurement relative error expression.

[0034] It should be further explained that the frequency coupling The calculation formula includes:

[0035]

[0036]

[0037] Where, Negative sequence coupling frequency Negative sequence current noise amplitude under ;

[0038] Positive sequence frequency The positive sequence current response signal amplitude under ;

[0039] is the positive sequence coupling frequency The positive sequence current noise amplitude under ;

[0040] Negative sequence frequency The negative sequence current response signal amplitude under ;

[0041] Negative sequence coupling frequency The negative sequence voltage noise amplitude under ;

[0042] Positive sequence frequency The amplitude of the positive sequence voltage response signal under ;

[0043] is the positive sequence coupling frequency The amplitude of the positive sequence voltage response signal under ;

[0044] Negative sequence frequency The negative sequence voltage response signal amplitude under .

[0045] It should be further explained that the relative error expression of the inverse method measurement including coupling compensation includes:

[0046]

[0047]

[0048]

[0049]

[0050]

[0051]

[0052]

[0053]

[0054] Where, Positive sequence frequency The voltage noise amplitude under ;

[0055] is the positive sequence coupling frequency The voltage noise amplitude under ;

[0056] Negative sequence frequency The voltage noise amplitude under ;

[0057] Negative sequence coupling frequency The voltage noise amplitude under ;

[0058] Positive sequence frequency The current noise amplitude under ;

[0059] is the positive sequence coupling frequency The current noise amplitude under ;

[0060] Negative sequence frequency The current noise amplitude under

[0061] Negative sequence coupling frequency The current noise amplitude under

[0062] Positive sequence frequency Positive sequence voltage noise-signal ratio under ;

[0063] Negative sequence frequency Negative sequence voltage noise-to-signal ratio under ;

[0064] Positive sequence frequency Positive sequence current noise-signal ratio under ;

[0065] Negative sequence frequency Negative sequence current noise-to-signal ratio under .

[0066] It should be further explained that the relative error expression of the uncompensated inversion method measurement includes:

[0067]

[0068]

[0069]

[0070]

[0071]

[0072]

[0073]

[0074]

[0075] Where, is the positive sequence coupling frequency Positive sequence voltage noise-signal ratio under ;

[0076] Negative sequence coupling frequency Negative sequence voltage noise-to-signal ratio under ;

[0077] is the positive sequence coupling frequency Positive sequence current noise-signal ratio under ;

[0078] Negative sequence coupling frequency Negative sequence current noise-to-signal ratio under ;

[0079] is the theoretical relative error of the SISO positive sequence admittance on the equipment side;

[0080] is the theoretical relative error of the SISO negative sequence admittance on the equipment side;

[0081] is the theoretical relative error of the SISO positive-sequence-negative-sequence coupling admittance on the equipment side;

[0082] is the theoretical relative error of the SISO negative-sequence-positive-sequence coupling admittance on the equipment side;

[0083] is the theoretical relative error of the SISO positive sequence impedance on the equipment side;

[0084] is the theoretical relative error of the SISO negative sequence impedance on the equipment side;

[0085] is the theoretical relative error of the SISO positive-sequence-negative-sequence coupling impedance on the equipment side;

[0086] is the theoretical relative error of the SISO negative-sequence-positive-sequence coupling impedance on the equipment side.

[0087] It should be further explained that 、 、 、 、 、

[0088] 、 、 The calculation formula is:

[0089]

[0090]

[0091]

[0092]

[0093] Where, The calculation formula is:

[0094] ;

[0095] The calculation formula is:

[0096] ;

[0097] 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:

[0098]

[0099] When the disturbance is a parallel current disturbance, for , the calculation formula is:

[0100]

[0101] in, represents the injected positive sequence disturbance voltage;

[0102] represents the injected positive sequence disturbance current;

[0103] is the transfer function between the disturbance signal and the response signal when a negative sequence disturbance is injected. When the disturbance is a series voltage disturbance, for , the calculation formula is:

[0104]

[0105] When the disturbance is a parallel current disturbance, for , the calculation formula is:

[0106]

[0107] in, represents the injected negative sequence disturbance voltage;

[0108] Represents the injected negative sequence disturbance current.

[0109] It should be further explained 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 measurement , SISO positive-sequence-negative-sequence coupling admittance The relative error of measurement , SISO negative sequence admittance The relative error of measurement , SISO negative-sequence-positive-sequence coupling admittance The relative error of measurement ;

[0110] The relative error of impedance measurement includes SISO positive sequence impedance The relative error of measurement , SISO positive-sequence-negative sequence coupling impedance The relative error of measurement , SISO negative sequence impedance The relative error of measurement , SISO negative-sequence-positive-sequence coupling impedance The relative error of measurement .

[0111] Among them, SISO refers to single-input single-output (Single-Input Single-Output).

[0112] It should be further explained that the measurement relative error expression constructed by the decoupling method includes:

[0113]

[0114]

[0115] .

[0116] It should be further explained that step S4 uses a numerical integration method to calculate the probability distribution of the numerator modulus value and the denominator modulus value. When there are two complex variables involved in the combined calculation in a numerator modulus value or a denominator modulus value, the step of calculating the probability distribution of the numerator modulus value or the denominator modulus value includes:

[0117] S401. Define two complex variables as and ,set up The amplitude distribution range is ,set up The amplitude distribution range is , let vector and modulus ,calculate The total probability distribution of:

[0118]

[0119] Where, is the conditional probability density function, and its expression is:

[0120] ;

[0121] for Probability distribution in the i-th amplitude interval;

[0122] for The probability distribution in the jth amplitude interval;

[0123] I is the indicator function, and its expression is:

[0124] ;

[0125] When there are three complex variables involved in the combined calculation of a numerator modulus or denominator modulus, first use two complex variables to execute step S401, 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 or denominator modulus.

[0126] In a second aspect, the present application provides an impedance / admittance measurement error evaluation system for implementing the above-mentioned integrated energy system impedance / admittance measurement error evaluation method, comprising:

[0127] The data acquisition and calculation module is used to collect noise signals of the target device at different frequencies and calculate the probability distribution of the noise amplitude at each frequency;

[0128] The frequency sweep measurement module is used to perform frequency sweep measurement on the target device to obtain the amplitude of the frequency sweep response signal at each frequency;

[0129] Noise-signal ratio calculation module, used to calculate the noise-signal ratio at each frequency The probability distribution of

[0130] Error expression building block, used to calculate relative measurement error by inversion method or decoupling method Expressions of

[0131] The module for calculating the probability distribution of modulus value is used to decompose the expression for calculating the relative error of measurement into the numerator and denominator of the expression, and calculate the modulus value of the numerator of the expression respectively. Sum expression denominator modulo value The probability distribution of

[0132] Logarithmic coordinate conversion and result calculation module, used to convert the expression numerator modulus Sum expression denominator modulo value Convert to the logarithmic coordinate system and calculate the probability distribution of the measurement relative error in the logarithmic coordinate system.

[0133] In a third aspect, the present application provides an electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor is configured to implement the steps of the above-mentioned impedance / admittance measurement error evaluation method when executing the computer program.

[0134] In a fourth aspect, the present application provides a storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the above-mentioned impedance / admittance measurement error evaluation method.

[0135] It can be seen from the above technical solutions that this application has the following advantages:

[0136] 1. This application collects noise signals from the target device at different frequencies and coupling frequencies, calculates the probability distribution of the noise amplitude based on kernel density estimation, and generates the probability distribution of the noise-signal ratio by combining the amplitude data of the swept frequency response signal. The actual noise data can be directly used to quickly fit the noise characteristics, thereby achieving accurate modeling of noise interference and avoiding the defect of the traditional Monte Carlo experiment method that relies on a large number of samples. The direct calculation of the probability density function significantly improves the evaluation efficiency, enabling error evaluation to shift from offline simulation to real-time analysis, providing data support for the dynamic optimization of disturbance signal design.

[0137] 2. This application targets scenarios where the internal resistance of the measurement equipment is small and the signal-to-noise ratio of the coupled frequency signal is low. By constructing a measurement relative error expression that includes frequency coupling compensation, the noise-to-signal ratio is dynamically associated with the amplitude of the swept frequency response signal, and the error contribution is accurately quantified. This solves the error evaluation distortion problem caused by ignoring the attenuation of the coupled frequency signal in traditional methods, and improves the evaluation reliability in low signal-to-noise ratio scenarios.

[0138] 3. After measuring the relative error expression, this application decomposes the measured relative error into the probability distribution of the numerator modulus value and the denominator modulus value, and calculates the probability distribution of the measured relative error based on the probability integral in the logarithmic coordinate system, intuitively characterizing the marginal impact of noise randomness on the measurement results, providing a quantitative basis for the credibility of the evaluation results, guiding the optimal selection of the disturbance signal amplitude and frequency points, and ultimately achieving high-precision impedance measurement.

[0139] 4. This application adopts an error expression construction strategy that combines the inversion method with the decoupling method to cover the error transmission path, and introduces a frequency coupling threshold judgment mechanism to dynamically select the compensation model, which effectively solves the problem of the traditional decoupling method ignoring 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 improves the accuracy of impedance and admittance measurement error evaluation, and provides a reliable basis for optimizing disturbance signal design and high-precision impedance measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0140] In order to more clearly illustrate the technical solution of the present application, the following is a brief introduction to the drawings required for the description. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0141] Figure 1 4 is a flow chart of a method for evaluating impedance / admittance measurement error in one embodiment of the present application.

[0142] Figure 2 This is a schematic diagram of an admittance / impedance measurement experimental platform in one embodiment of the present application.

[0143] Figure 3 is a diagram of simulated noise power density in one embodiment of the present application.

[0144] Figure 4 This is a comparison chart of the theoretical confidence interval calculated by an embodiment of the present application and the actual confidence interval obtained by Monte Carlo simulation.

[0145] Figure 5 It is the MIMO frequency coupling sequence impedance in one embodiment of the present application Comparison chart of measured error and confidence level at a frequency of 25Hz.

[0146] Figure 6 It is the MIMO frequency coupling sequence impedance in one embodiment of the present application Comparison chart of measured error and confidence level at frequency 55Hz.

[0147] Figure 7 It is the MIMO frequency coupling sequence impedance in one embodiment of the present application Comparison chart of measured error and confidence level at a frequency of 70Hz.

[0148] Figure 8 It is the MIMO frequency coupling sequence impedance in one embodiment of the present application Comparison chart of measured error and confidence level at frequency 105Hz.

[0149] Figure 9It is the MIMO frequency coupling sequence impedance in one embodiment of the present application Comparison chart of measured error and confidence level at frequency 205Hz.

[0150] Figure 10 Schematic diagram of frequency sweep and error band of decoupling method and inversion method in a noisy environment in one embodiment of the present application;

[0151] in, Figure 10 (a) is a schematic diagram of amplitude. Figure 10 (b) is a phase angle diagram.

[0152] Figure 11 4 is a schematic block diagram of an impedance / admittance measurement error evaluation system in one embodiment of the present application.

[0153] Figure 12 It is a schematic diagram of the hardware structure of an electronic device in one embodiment of the present application. DETAILED DESCRIPTION

[0154] In order to make the application objectives, features, and advantages of this application more obvious and easy to understand, the technical solutions protected by this application will be clearly and completely described below using specific embodiments and drawings. Obviously, the embodiments described below are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0155] The following describes in detail the impedance / admittance measurement error evaluation method involved in this application. Specific details, such as specific system structures and techniques, are provided for illustrative purposes, not for limitation, to facilitate a thorough understanding of the embodiments of this application. However, it should be apparent to those skilled in the art that this application may also be implemented in other embodiments without these specific details.

[0156] In the impedance / admittance measurement error evaluation method disclosed herein, the term "comprising" indicates the presence of the described features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or combinations thereof. The terms "include," "comprising," "having," and their variations all mean "including but not limited to," unless otherwise specifically emphasized.

[0157] The impedance / admittance measurement error evaluation method provided in the embodiment of the present application is executed by a computer device. Accordingly, the impedance / admittance measurement error evaluation system runs in the computer device.

[0158] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application.

[0159] Figure 1 Flowchart of a method for evaluating impedance / admittance measurement error according to an embodiment of the present application. Figure 1 The execution subject may be an impedance / admittance measurement error evaluation system. According to different requirements, the order of the steps in the flowchart may be changed, and some steps may be omitted.

[0160] like Figure 1 As shown in FIG, the impedance / admittance measurement error evaluation method includes:

[0161] Step S1: Collect noise signals of the target device at different frequencies and calculate the probability distribution of the noise amplitude at each frequency. The noise signal includes voltage noise and current noise.

[0162] By collecting the voltage and current noise signals of the target device at different frequencies and coupling frequencies and calculating their amplitude probability distribution, a multi-dimensional noise characteristic data foundation is provided for subsequent error analysis, ensuring that the noise interference characteristics of the device under different working conditions are covered, and an accurate data model is established to quantify the impact of noise on measurement.

[0163] 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 statistical noise amplitude through kernel density estimation.

[0164] The noise can be statistically analyzed by sampling the actual noise data. The probability distribution of amplitude at different frequencies. Assume that the sweep sampling time is , extract the duration from the observation data before frequency sweep The time series data is divided into After FFT calculation (i.e. fast discrete Fourier transform), the kernel function method is used to calculate the Probability distribution of amplitude at different frequencies.

[0165] Density estimation of FFT segmented data using the kernel function method 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 noise probability density estimation.

[0166] Step S2, performing a frequency sweep measurement on the target device, injecting a disturbance signal at each frequency to obtain the amplitude of the frequency sweep response signal at each frequency, where the frequency sweep response signal includes a voltage response signal and a current response signal;

[0167] Calculate the noise-to-signal ratio at each frequency The probability distribution of the noise-signal ratio is the ratio of the noise amplitude to the corresponding swept frequency response signal amplitude, including the voltage noise-signal ratio and current noise-to-signal ratio .

[0168] By combining the swept frequency response signal amplitude and the noise amplitude to calculate the noise-to-signal ratio probability distribution at each frequency, an accurate quantitative evaluation of the energy relationship between noise and useful signal can be achieved, providing key input parameters for subsequent error modeling.

[0169] In some embodiments, the noise-to-signal ratio The calculation formula is:

[0170]

[0171] Where, is the noise amplitude, is the amplitude of the swept frequency response signal;

[0172] In the sample interval The calculation formula for the internal probability is:

[0173]

[0174] Where, express The i-th amplitude interval of ;

[0175] express In the The average value of the amplitude interval;

[0176] Indicates the number of The kernel density of the amplitude interval is obtained by fitting the actual noise data using the kernel function method.

[0177] Among them, the sweep frequency response signal amplitude Noise-Signal Ratio The relationship can be expressed as:

[0178]

[0179] Where, For a measurement signal with superimposed noise, it is not difficult to see that the noise measurement error is the inverse of the signal-to-noise ratio (SNR), that is, the noise-signal ratio (NSR). The NSR of a signal can also reflect the relative error of the amplitude of the signal itself. , relative phase error The maximum value of:

[0180] .

[0181] By establishing a probability calculation model of the noise-signal ratio in a discrete interval and combining it with kernel density fitting of actual noise data, we can achieve refined modeling of the probability characteristics of noise interference and provide a reliable statistical basis for error propagation analysis.

[0182] Step S3, calculate the relative error of measurement by inversion method or decoupling method The expression of measurement relative error Including the relative error of admittance measurement and impedance measurement relative error .

[0183] By constructing a measurement relative error expression that includes two types of parameters, admittance and impedance, it fully covers the core parameter types required for power system stability analysis, and provides two error modeling paths, the inversion method and the decoupling method, to adapt to the needs of different measurement scenarios.

[0184] In some specific embodiments, when constructing the measurement relative error expression by the inversion method, the admittance measurement relative error Including MIMO positive sequence admittance measurement relative error , MIMO negative sequence admittance measurement relative error , MIMO positive-sequence-negative-sequence coupled admittance measurement relative error , MIMO negative-sequence-positive sequence coupled admittance measurement relative error ;

[0185] Impedance measurement relative error Including MIMO positive sequence impedance measurement relative error , MIMO negative sequence impedance measurement relative error , MIMO positive-sequence-negative-sequence coupling impedance measurement relative error , MIMO negative-sequence-positive sequence coupling impedance measurement relative error .

[0186] The inversion method is commonly used in dq impedance measurements and is also applicable to determining sequence impedance. The inversion method calculates the MIMO sequence impedance. Therefore, the relative error in admittance measurements using the inversion method is the relative error in the MIMO sequence admittance or coupling admittance measurements. The same applies to the relative error in impedance measurements. The MIMO sequence impedance calculated using the inversion method can be converted to the dq impedance after frequency shifting, hence the name "accurate sequence impedance." The inversion method injects two linearly independent perturbation signals during measurement to ensure linearly independent response signals between the two sets of voltage and current. Impedance is then calculated using matrix inversion.

[0187] By classifying the measurement error types of admittance and impedance, a complete sequence impedance parameter error evaluation system is established to meet the differentiated requirements for parameter accuracy in multi-dimensional stability analysis of power electronic equipment.

[0188] In some specific embodiments, the step of constructing a measurement relative error expression by an inversion method includes:

[0189] S301. Calculate frequency coupling , including the positive-sequence-negative-sequence coupling of admittance , Admittance negative sequence-positive sequence coupling , Impedance positive sequence-negative sequence coupling , Impedance negative sequence-positive sequence coupling ;

[0190] S302. Determine frequency coupling Is it lower than a preset threshold? If so, construct an inverse method measurement relative error expression including coupling degree compensation;

[0191] If not, then construct an uncompensated inversion method measurement relative error expression.

[0192] By introducing a frequency coupling threshold judgment mechanism, an adaptive error expression generation strategy is constructed to avoid overcompensation while ensuring calculation accuracy, thus realizing intelligent configuration of the measurement error model.

[0193] In some embodiments, the frequency coupling The calculation formula includes:

[0194]

[0195]

[0196] Where, Negative sequence coupling frequency Negative sequence current noise amplitude under ;

[0197] Positive sequence frequency The positive sequence current response signal amplitude under ;

[0198] is the positive sequence coupling frequency The positive sequence current noise amplitude under ;

[0199] Negative sequence frequency The negative sequence current response signal amplitude under ;

[0200] Negative sequence coupling frequency The negative sequence voltage noise amplitude under ;

[0201] Positive sequence frequency The amplitude of the positive sequence voltage response signal under ;

[0202] is the positive sequence coupling frequency The amplitude of the positive sequence voltage response signal under ;

[0203] Negative sequence frequency The negative sequence voltage response signal amplitude under .

[0204] By defining a frequency coupling calculation formula based on the ratio of positive and negative sequence components, a quantitative correlation model between device coupling characteristics and noise propagation path is established, providing key characteristic parameters for error compensation.

[0205] In some specific embodiments, the relative error expression of the inverse method measurement including coupling degree compensation includes:

[0206]

[0207]

[0208]

[0209]

[0210]

[0211]

[0212]

[0213]

[0214] Where, Positive sequence frequency The voltage noise amplitude under ;

[0215] is the positive sequence coupling frequency The voltage noise amplitude under ;

[0216] Negative sequence frequency The voltage noise amplitude under ;

[0217] Negative sequence coupling frequency The voltage noise amplitude under ;

[0218] Positive sequence frequency The current noise amplitude under

[0219] is the positive sequence coupling frequency The current noise amplitude under

[0220] Negative sequence frequency The current noise amplitude under ;

[0221] Negative sequence coupling frequency The current noise amplitude under ;

[0222] Positive sequence frequency Positive sequence voltage noise-signal ratio under ;

[0223] Negative sequence frequency Negative sequence voltage noise-to-signal ratio under ;

[0224] Positive sequence frequency Positive sequence current noise-signal ratio under ;

[0225] Negative sequence frequency Negative sequence current noise-to-signal ratio under .

[0226] By constructing an error expression model with coupling degree compensation, a second-order compensation correction term is introduced on the basis of retaining the main error term, which significantly improves the error evaluation accuracy under high coupling conditions.

[0227] In some specific embodiments, the relative error expression of the uncompensated inversion method measurement includes:

[0228]

[0229]

[0230]

[0231]

[0232]

[0233]

[0234]

[0235]

[0236] Where, is the positive sequence coupling frequency Positive sequence voltage noise-signal ratio under ;

[0237] Negative sequence coupling frequency Negative sequence voltage noise-to-signal ratio under ;

[0238] is the positive sequence coupling frequency Positive sequence current noise-signal ratio under ;

[0239] Negative sequence coupling frequency Negative sequence current noise-to-signal ratio under ;

[0240] is the theoretical relative error of the SISO positive sequence admittance on the equipment side;

[0241] is the theoretical relative error of the SISO negative sequence admittance on the equipment side;

[0242] is the theoretical relative error of the SISO positive-sequence-negative-sequence coupling admittance on the equipment side;

[0243] is the theoretical relative error of the SISO negative-sequence-positive-sequence coupling admittance on the equipment side;

[0244] is the theoretical relative error of the SISO positive sequence impedance on the equipment side;

[0245] is the theoretical relative error of the SISO negative sequence impedance on the equipment side;

[0246] is the theoretical relative error of the SISO positive-sequence-negative-sequence coupling impedance on the equipment side;

[0247] is the theoretical relative error of the SISO negative-sequence-positive-sequence coupling impedance on the equipment side.

[0248] By establishing a simplified error expression under uncompensated conditions, a balance between computational efficiency and accuracy is achieved in highly coupled scenarios, providing a lightweight solution for rapid error evaluation.

[0249] Matrix inversion method is used to calculate When the noise interference is considered, the calculation results Can be written as:

[0250]

[0251] So calculate The measurement error You can write:

[0252]

[0253] Where S1 and S2 are related to the theoretical error and frequency coupling:

[0254]

[0255] When the internal resistance of the measuring device is small, the relative error of the sub-diagonal element of the impedance or admittance approaches 0. Here, assuming that the relative error of the sub-diagonal element of the admittance is close to 0, it can be seen that S1 and S2 are both much smaller than 1, so S 1 S 2 related terms can be ignored; , NSR and S1 、S 2 is inversely proportional, so It can be retained. After simplifying the numerator and denominator, we can finally derive The relative error :

[0256]

[0257] According to the above derivation process, we can get 、 、 The expression of , and the measurement error expression of the corresponding impedance is obtained through the impedance-admittance duality relationship.

[0258] Since the signal is buried in noise in actual measurements, there is no theoretical method to extract the ideal signal in a noisy environment. In other words, whether filtering or multiple averaging, the NSR of the signal can only be reduced as much as possible. This means that the NSR in error assessment can only be obtained through approximation:

[0259]

[0260] This approximation is fine when the SNR is not large. However, in actual measurement, it is found that when the frequency coupling is K When it is lower, and When <<1, the signal-to-noise ratio at the coupling frequency will be very low. For example, under the condition of series voltage, , 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 K When the value is lower than the preset threshold, the inverse method with coupling degree compensation is used to measure the relative error expression to estimate the measurement error caused by the noise.

[0261] In some specific embodiments, 、 、 、 、 、

[0262] 、 、 The calculation formula is:

[0263]

[0264]

[0265]

[0266]

[0267] Where, The calculation formula is:

[0268] ;

[0269] The calculation formula is:

[0270] ;

[0271] 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:

[0272]

[0273] When the disturbance is a parallel current disturbance, for , the calculation formula is:

[0274]

[0275] in, represents the injected positive sequence disturbance voltage;

[0276] represents the injected positive sequence disturbance current;

[0277] is the transfer function between the disturbance signal and the response signal when a negative sequence disturbance is injected. When the disturbance is a series voltage disturbance, for , the calculation formula is:

[0278]

[0279] When the disturbance is a parallel current disturbance, for , the calculation formula is:

[0280]

[0281] in, represents the injected negative sequence disturbance voltage;

[0282] Represents the injected negative sequence disturbance current.

[0283] Among them, when the positive sequence voltage is connected in series and the positive sequence current is connected in parallel, and Write respectively:

[0284]

[0285] ;

[0286] in, is the positive sequence admittance on the equipment side, ;

[0287] is the positive sequence admittance on the grid side;

[0288] is the positive sequence impedance on the equipment side, ;

[0289] is the positive sequence impedance on the grid side;

[0290] Taking the series voltage disturbance as an example, when , hour, , , and , The following relationship exists:

[0291]

[0292] ;

[0293] Defining the coupling frequency 、 The product of positive sequence and negative sequence voltage and frequency 、 The ratio of the product of the positive and negative sequence voltages is :

[0294] ;

[0295] So the positive sequence admittance Theoretical relative error You can write:

[0296] ;

[0297] Same definition Indicates coupling frequency 、 The product of positive sequence and negative sequence current and frequency 、 The ratio of the product of positive and negative sequence currents:

[0298] ;

[0299] Then the positive sequence impedance The relative error This can be evaluated as follows:

[0300]

[0301] Replacing all subscripts p in the above equation with subscript n allows for error evaluation of negative sequence admittance and impedance.

[0302] Since the deviation between the approximate value and the actual value in the above-mentioned relationship is extremely small, for the convenience of calculation, the approximate equality sign is regarded as the equal sign in the calculation of this scheme.

[0303] By constructing a mathematical relationship model between theoretical relative error and grid equipment parameters, the abstract error quantity is converted into a measurable combination of physical quantities, thus achieving accurate positioning and quantitative analysis of the error source.

[0304] In some specific embodiments, 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 measurement , SISO positive-sequence-negative-sequence coupling admittance The relative error of measurement , SISO negative sequence admittance The relative error of measurement , SISO negative-sequence-positive-sequence coupling admittance The relative error of measurement ;

[0305] The relative error of impedance measurement includes SISO positive sequence impedance The relative error of measurement , SISO positive-sequence-negative sequence coupling impedance The relative error of measurement , SISO negative sequence impedance The relative error of measurement , SISO negative-sequence-positive-sequence coupling impedance The relative error of measurement .

[0306] Among them, the decoupling method decouples the 2×2 sequence admittance matrix into two SISO admittances and Therefore, the relative errors in admittance measurements using the decoupling method are the same as the relative errors in SISO sequence admittance or coupling admittance. The same applies to impedance measurement errors. Because the decoupled admittance includes the source-side admittance, some call it the grid-considered sequence admittance.

[0307] By expanding the error evaluation objects of the decoupling method to positive and negative sequence coupling parameters, a complete decoupling error evaluation system is established, and the ability to analyze measurement errors of complex coupling systems is improved.

[0308] In some specific embodiments, the measurement relative error expression constructed by the decoupling method includes:

[0309]

[0310]

[0311] .

[0312] By establishing an independent calculation model for each parameter error of the decoupling method, parallel calculation of multi-parameter errors is realized, which significantly improves the computational efficiency and feasibility of the decoupling method error evaluation.

[0313] Step S4, decompose the expression for calculating the relative measurement error into the expression numerator and the expression denominator, and calculate the expression numerator modulus respectively Sum expression denominator modulo value The probability distribution of .

[0314] By decomposing the error expression into the numerator modulus and denominator modulus and independently calculating their probability distribution, the statistical characteristics of the error components are effectively separated, and an operational mathematical processing framework is established for subsequent error synthesis.

[0315] In some specific embodiments, a numerical integration method is used to calculate the probability distribution of the numerator modulus value and the denominator modulus value. When there are two complex variables involved in the combined calculation in a numerator modulus value or a denominator modulus value, the step of calculating the probability distribution of the numerator modulus value or the denominator modulus value includes:

[0316] S401. Define two complex variables as and ,set up The amplitude distribution range is ,set up The amplitude distribution range is , let vector and modulus be ,calculate The total probability distribution of:

[0317]

[0318] Where, is the conditional probability density function, and its expression is:

[0319] ;

[0320] for Probability distribution in the i-th amplitude interval;

[0321] for The probability distribution in the jth amplitude interval;

[0322] I is the indicator function, and its expression is:

[0323] ;

[0324] When there are three complex variables involved in the combined calculation of a numerator modulus or denominator modulus, first use two complex variables to execute step S401, 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 or denominator modulus.

[0325] By constructing a probabilistic synthesis algorithm for the modular values ​​of complex variable combinations, we overcome the computational difficulties of multivariate joint distribution and provide a feasible numerical analytical method for complex error propagation processes.

[0326] S5. Modulate the expression numerator Sum expression denominator modulo value Convert to the logarithmic coordinate system and calculate the probability distribution of the relative error in the logarithmic coordinate system through convolution calculation. The formula is:

[0327]

[0328] Where, Relative measurement error Amplitude is expressed in decibels;

[0329] For the The numerator modulus of the expression for the amplitude interval is, To calculate the The expression of the amplitude interval is a function of the probability distribution of the molecular modulus value in the logarithmic coordinate system;

[0330] To calculate the The function of the probability distribution of the denominator modulus of the expression of the amplitude interval in the logarithmic coordinate system;

[0331] for The starting bin index of for The ending bin index.

[0332] By converting the modulus value to a logarithmic coordinate system and constructing a probability distribution synthesis formula, the linearization of the complex error transmission process is achieved, significantly reducing the computational complexity of multidimensional probability distribution synthesis.

[0333] In a specific embodiment, a method for evaluating impedance / admittance measurement error includes:

[0334] Step S1, collecting noise signals of the target device at different frequencies, where the noise signals include voltage noise and current noise;

[0335] 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 statistical noise amplitude through kernel density estimation.

[0336] Step S2, performing a frequency sweep measurement on the target device, injecting a disturbance signal at each frequency to obtain the amplitude of the frequency sweep response signal at each frequency, where the frequency sweep response signal includes a voltage response signal and a current response signal;

[0337] Calculate the noise-to-signal ratio at each frequency The probability distribution of the noise-signal ratio is the ratio of the noise amplitude to the corresponding swept frequency response signal amplitude, including the voltage noise-signal ratio and current noise-to-signal ratio , noise-to-signal ratio The calculation formula is:

[0338]

[0339] Where, is the noise amplitude, is the amplitude of the swept frequency response signal;

[0340] In the sample interval The calculation formula for the internal probability is:

[0341]

[0342] Where, express The i-th amplitude interval of ;

[0343] express In the The average value of the amplitude interval;

[0344] Indicates the number of The kernel density of the amplitude interval is obtained by fitting the actual noise data using the kernel function method.

[0345] Step S3, calculate the relative error of measurement by inversion method or decoupling method The expression of measurement relative error Including the relative error of admittance measurement and impedance measurement relative error ;

[0346] When constructing the measurement relative error expression by the inversion method, the admittance measurement relative error Including MIMO positive sequence admittance measurement relative error , MIMO negative sequence admittance measurement relative error , MIMO positive-sequence-negative-sequence coupled admittance measurement relative error , MIMO negative-sequence-positive sequence coupled admittance measurement relative error :

[0347] Impedance measurement relative error Including MIMO positive sequence impedance measurement relative error , MIMO negative sequence impedance measurement relative error , MIMO positive-sequence-negative-sequence coupling impedance measurement relative error , MIMO negative-sequence-positive sequence coupling impedance measurement relative error ;

[0348] The steps to construct the measurement relative error expression by the inversion method include:

[0349] S301. Calculate frequency coupling , including the positive-sequence-negative-sequence coupling of admittance , Admittance negative sequence-positive sequence coupling , Impedance positive sequence-negative sequence coupling , Impedance negative sequence-positive sequence coupling ;

[0350] S302. Determine frequency coupling Is it lower than a preset threshold? If so, construct an inverse method measurement relative error expression including coupling degree compensation;

[0351] If not, then construct an uncompensated inversion method measurement relative error expression.

[0352] Among them, the frequency coupling The calculation formula includes:

[0353]

[0354]

[0355] Where, Negative sequence coupling frequency Negative sequence current noise amplitude under ;

[0356] Positive sequence frequency The positive sequence current response signal amplitude under ;

[0357] is the positive sequence coupling frequency The positive sequence current noise amplitude under ;

[0358] Negative sequence frequency The negative sequence current response signal amplitude under ;

[0359] Negative sequence coupling frequency The negative sequence voltage noise amplitude under ;

[0360] Positive sequence frequency The amplitude of the positive sequence voltage response signal under ;

[0361] is the positive sequence coupling frequency The amplitude of the positive sequence voltage response signal under ;

[0362] Negative sequence frequency The amplitude of the negative sequence voltage response signal under ;

[0363] The relative error expression of the inverse method measurement including coupling degree compensation includes:

[0364]

[0365]

[0366]

[0367]

[0368]

[0369]

[0370]

[0371]

[0372] Where, Positive sequence frequency The voltage noise amplitude under ;

[0373] is the positive sequence coupling frequency The voltage noise amplitude under ;

[0374] Negative sequence frequency The voltage noise amplitude under ;

[0375] Negative sequence coupling frequency The voltage noise amplitude under ;

[0376] Positive sequence frequency The current noise amplitude under

[0377] is the positive sequence coupling frequency The current noise amplitude under

[0378] Negative sequence frequency The current noise amplitude under

[0379] Negative sequence coupling frequency The current noise amplitude under

[0380] Positive sequence frequency Positive sequence voltage noise-signal ratio under ;

[0381] Negative sequence frequency Negative sequence voltage noise-to-signal ratio under ;

[0382] Positive sequence frequency Positive sequence current noise-signal ratio under ;

[0383] Negative sequence frequency Negative sequence current noise-to-signal ratio under ;

[0384] The relative error expression of the uncompensated inversion method measurement includes:

[0385]

[0386]

[0387]

[0388]

[0389]

[0390]

[0391]

[0392]

[0393] Where, is the positive sequence coupling frequency Positive sequence voltage noise-signal ratio under ;

[0394] Negative sequence coupling frequency Negative sequence voltage noise-to-signal ratio under ;

[0395] is the positive sequence coupling frequency Positive sequence current noise-signal ratio under ;

[0396] Negative sequence coupling frequency Negative sequence current noise-to-signal ratio under ;

[0397] is the theoretical relative error of the SISO positive sequence admittance on the equipment side;

[0398] is the theoretical relative error of the SISO negative sequence admittance on the equipment side;

[0399] is the theoretical relative error of the SISO positive-sequence-negative-sequence coupling admittance on the equipment side;

[0400] is the theoretical relative error of the SISO negative-sequence-positive-sequence coupling admittance on the equipment side;

[0401] is the theoretical relative error of the SISO positive sequence impedance on the equipment side;

[0402] is the theoretical relative error of the SISO negative sequence impedance on the equipment side;

[0403] is the theoretical relative error of the SISO positive-sequence-negative-sequence coupling impedance on the equipment side;

[0404] is the theoretical relative error of the SISO negative-sequence-positive-sequence coupling impedance on the equipment side;

[0405] 、 、 、 、 、

[0406] 、 、 The calculation formula is:

[0407]

[0408]

[0409]

[0410]

[0411] Where, The calculation formula is:

[0412] ;

[0413] The calculation formula is:

[0414] ;

[0415] 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:

[0416]

[0417] When the disturbance is a parallel current disturbance, for , the calculation formula is:

[0418]

[0419] in, represents the injected positive sequence disturbance voltage;

[0420] represents the injected positive sequence disturbance current;

[0421] is the transfer function between the disturbance signal and the response signal when a negative sequence disturbance is injected. When the disturbance is a series voltage disturbance, for , the calculation formula is:

[0422]

[0423] When the disturbance is a parallel current disturbance, for , the calculation formula is:

[0424]

[0425] in, represents the injected negative sequence disturbance voltage;

[0426] Represents the injected negative sequence disturbance current.

[0427] When constructing the measurement relative error expression by decoupling method, the admittance measurement relative error Including SISO positive sequence admittance The relative error of measurement , SISO positive-sequence-negative-sequence coupling admittance The relative error of measurement , SISO negative sequence admittance The relative error of measurement , SISO negative-sequence-positive-sequence coupling admittance The relative error of measurement ;

[0428] The relative error of impedance measurement includes SISO positive sequence impedance The relative error of measurement , SISO positive-sequence-negative sequence coupling impedance The relative error of measurement , SISO negative sequence impedance The relative error of measurement , SISO negative-sequence-positive-sequence coupling impedance The relative error of measurement ;

[0429] The relative error expression of measurement constructed by the decoupling method includes:

[0430]

[0431]

[0432] .

[0433] Step S4, decompose the expression for calculating the relative measurement error into the expression numerator and the expression denominator, and calculate the expression numerator modulus respectively Sum expression denominator modulo value When there are two complex variables involved in the combined calculation of a numerator modulus value or a denominator modulus value, the steps of calculating the probability distribution of the numerator modulus value or the denominator modulus value include:

[0434] S401. Define two complex variables as and ,set up The amplitude distribution range is ,set up The amplitude distribution range is , let vector and modulus be ,calculate The total probability distribution of:

[0435]

[0436] Where, is the conditional probability density function, and its expression is:

[0437] ;

[0438] for Probability distribution in the i-th amplitude interval;

[0439] for The probability distribution in the jth amplitude interval;

[0440] I is the indicator function, and its expression is:

[0441] ;

[0442] When there are three complex variables involved in the combined calculation of a numerator modulus or denominator modulus, first use two complex variables to execute step S401, 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 or denominator modulus.

[0443] Step S5, modulus the expression numerator Sum expression denominator modulo value Convert to the logarithmic coordinate system and calculate the probability distribution of the relative error in the logarithmic coordinate system through convolution calculation. The formula is:

[0444]

[0445] Where, Relative measurement error Amplitude is expressed in decibels;

[0446] For the The numerator modulus of the expression for the amplitude interval is, To calculate the The expression of the amplitude interval is a function of the probability distribution of the molecular modulus value in the logarithmic coordinate system;

[0447] To calculate the The function of the probability distribution of the denominator modulus of the expression of the amplitude interval in the logarithmic coordinate system;

[0448] for The starting bin index of for The ending bin index.

[0449] The impedance / admittance measurement error evaluation experiment is performed using the method of this embodiment. A series voltage disturbance is injected into the admittance / impedance measurement experimental platform. The schematic diagram of the admittance / impedance measurement experimental platform is shown in FIG. Figure 2 As shown in the figure, the simulated noise power density diagram generated based on a section of noise data intercepted in the actual measurement is as follows Figure 3 shown.

[0450] from Figure 3 It can be seen that the noise presents an obvious pink feature in the low frequency band, that is, the power density of the noise decreases as the frequency increases.

[0451] The data measured in steps 1-2 of this embodiment are used to perform Monte Carlo simulation. The number of Monte Carlo simulations is 10 5 The actual confidence interval is obtained and compared with the theoretical confidence interval calculated in this embodiment. The comparison chart is as follows: Figure 4 As shown;

[0452] from Figure 4 It can be seen that although the number of Monte Carlo simulations is 10 5 However, the waveform still has a relatively obvious sawtooth feeling, and the theoretical probability distribution calculation method adopted in this embodiment (as shown by the red line) can reflect the probability distribution more accurately.

[0453] The MIMO frequency coupling sequence impedance calculated in this embodiment The comparison of measured error and confidence level at each frequency is shown in the figure below: Figure 5-Figure 9 As shown;

[0454] Figure 5-Figure 9 The blue circle line in the figure represents the measurement relative error modulus caused by noise in 100 actual measurements, while the red line represents the measurement relative error modulus prediction value with confidence levels of 90%, 95% and 99%, respectively. Figure 5-Figure 9 It can be seen that most of the actual measurement errors are within the predicted range, which proves the reliability of the error calculation method proposed in this application.

[0455] In this embodiment, the frequency sweep and error band diagram of the decoupling method and the inversion method in a noise environment is as follows: Figure 10 As shown, Figure 10 (a) is the amplitude diagram, (b) is the phase angle diagram;

[0456] Figure 10 In the figure, the red line is the MIMO frequency coupling sequence impedance calculated by the inverse method. 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 inversion method, and the light purple band is the error band of the decoupling method. The blue dots are the measured values ​​of the inversion method under a noisy environment, and the green triangles are the measured values ​​of the decoupling method under a noisy environment. Figure 10 It can be seen from the figure that as the frequency increases, the error band of the inversion method will be larger than the error band of the decoupling method, which means that the measurement error of the inversion method will be larger than the measurement error of the decoupling method under certain circumstances.

[0457] The following is an embodiment of an impedance / admittance measurement error evaluation system provided in an embodiment of the present disclosure. The impedance / admittance measurement error evaluation system and the impedance / admittance measurement error evaluation method of the above-mentioned embodiments belong to the same inventive concept. For details not fully described in the embodiment of the impedance / admittance measurement error evaluation system, reference can be made to the embodiment of the above-mentioned impedance / admittance measurement error evaluation method.

[0458] A mobile terminal implementing various embodiments of the present application will now be described with reference to the accompanying drawings. In the subsequent description, suffixes such as "module," "component," or "unit" used to represent components are used solely to facilitate description of the embodiments of the present application and do not inherently have specific meanings. Therefore, "module" and "component" may be used interchangeably.

[0459] like Figure 11 As shown in Figure 1, the impedance / admittance measurement error evaluation system includes:

[0460] The data acquisition and calculation module is used to collect noise signals of the target device at different frequencies and calculate the probability distribution of the noise amplitude at each frequency;

[0461] The frequency sweep measurement module is used to perform frequency sweep measurement on the target device to obtain the amplitude of the frequency sweep response signal at each frequency;

[0462] Noise-signal ratio calculation module, used to calculate the noise-signal ratio at each frequency The probability distribution of

[0463] Error expression building block, used to calculate relative measurement error by inversion method or decoupling method Expressions of

[0464] The module for calculating the probability distribution of modulus value is used to decompose the expression for calculating the relative error of measurement into the numerator and denominator of the expression, and calculate the modulus value of the numerator of the expression respectively. Sum expression denominator modulo value The probability distribution of

[0465] Logarithmic coordinate conversion and result calculation module, used to convert the expression numerator modulus Sum expression denominator modulo value Convert to the logarithmic coordinate system and calculate the probability distribution of the measurement relative error in the logarithmic coordinate system.

[0466] The evaluation system for impedance / admittance measurement errors of an integrated energy system of this embodiment is used to implement an evaluation method for impedance / admittance measurement errors.

[0467] The present application also provides an electronic device for implementing various embodiments of the present application. The electronic device includes a memory, a processor, and a computer program stored in the memory and executable on the processor.

[0468] Those skilled in the art will understand that the electronic device structure involved in the embodiments of the present 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 certain components, or arrange the components differently.

[0469] Figure 12 A schematic diagram of the hardware structure of an electronic device for implementing various embodiments of the present application.

[0470] The electronic device includes, but is not limited to, components such as a processor and a memory. Those skilled in the art will appreciate that the electronic device structures described in the embodiments of the present application do not limit the electronic device, and the electronic device may include more or fewer components than shown, or may combine certain components or arrange the components differently.

[0471] The present application also provides a storage medium storing a program product capable of implementing a method for evaluating impedance / admittance measurement errors. In some possible implementations, various aspects of the present disclosure may also be implemented in the form of a program product comprising program code. When the program product is executed on a terminal device, the program code is configured to cause the terminal device to execute the steps described in the "Exemplary Methods" section above according to various exemplary embodiments of the present disclosure.

[0472] The storage medium may be any combination of one or more readable media. The readable medium may be a readable signal medium or a readable storage medium. The readable storage medium may be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device, or component, or any combination thereof.

[0473] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present application. Various modifications to these embodiments will be readily apparent to one 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. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to 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: include: S1. Collect noise signals from the target device at different frequencies and calculate the probability distribution of the noise amplitude at each frequency. The noise signal includes voltage noise and current noise. S2. Perform a frequency sweep measurement on the target device by injecting a disturbance signal at each frequency to obtain the amplitude of the frequency sweep response signal at each frequency. The frequency sweep response signal includes a voltage response signal and a current response signal. Calculate the noise-to-signal ratio at each frequency The probability distribution of the noise-signal ratio is the ratio of the noise amplitude to the corresponding swept frequency response signal amplitude, including the voltage noise-signal ratio and current noise-to-signal ratio ; S3. Calculate the relative measurement error by inversion method or decoupling method The expression of measurement relative error Including the relative error of admittance measurement and impedance measurement relative error ; S4. Decompose the expression for calculating the relative measurement error into the numerator and denominator, and calculate the modulus of the numerator and denominator respectively. Sum expression denominator modulo value The probability distribution of S5. Modulate the expression numerator Sum expression denominator modulo value Convert to the logarithmic coordinate system and calculate the probability distribution of the relative error in the logarithmic coordinate system through convolution calculation. The formula is: Where, Relative measurement error Amplitude is expressed in decibels; For the The numerator modulus of the expression for the amplitude interval is, To calculate the The expression of the amplitude interval is a function of the probability distribution of the molecular modulus value in the logarithmic coordinate system; To calculate the The function of the probability distribution of the denominator modulus of the expression of the amplitude interval in the logarithmic coordinate system; for The starting bin index of for The ending bin index.

2. The evaluation method according to claim 1, wherein: In step S2, the noise-signal ratio The calculation formula is: Where, is the noise amplitude, is the amplitude of the swept frequency response signal; In the sample interval The calculation formula for the internal probability is: Where, express No. i Amplitude intervals; express In the The average value of the amplitude interval; express M arrive N-1 The first in the range The kernel density of the amplitude interval is obtained by fitting the actual noise data using the kernel function method.

3. The evaluation method according to claim 1, wherein: In step S3, when constructing the measurement relative error expression by the inversion method, the admittance measurement relative error Including MIMO positive sequence admittance measurement relative error , MIMO negative sequence admittance measurement relative error , MIMO positive-sequence-negative-sequence coupled admittance measurement relative error , MIMO negative-sequence-positive sequence coupled admittance measurement relative error ; Impedance measurement relative error Including MIMO positive sequence impedance measurement relative error , MIMO negative sequence impedance measurement relative error , MIMO positive-sequence-negative-sequence coupling impedance measurement relative error , MIMO negative-sequence-positive sequence coupling impedance measurement relative error .

4. The evaluation method according to claim 3, wherein: The steps to construct the measurement relative error expression by the inversion method include: S301. Calculate frequency coupling , including the positive-sequence-negative-sequence coupling of admittance , Admittance negative sequence-positive sequence coupling , Impedance positive sequence-negative sequence coupling , Impedance negative sequence-positive sequence coupling ; S302. Determine frequency coupling Is it lower than the preset threshold? If so, construct an inverse method measurement relative error expression including coupling degree compensation; If not, then construct an uncompensated inversion method measurement relative error expression.

5. The evaluation method according to claim 4, wherein: The relative error expression of the inverse method measurement including coupling degree compensation includes: Where, Positive sequence frequency The voltage noise amplitude under ; is the positive sequence coupling frequency The voltage noise amplitude under ; Negative sequence frequency The voltage noise amplitude under ; Negative sequence coupling frequency The voltage noise amplitude under ; Positive sequence frequency The current noise amplitude under ; is the positive sequence coupling frequency The current noise amplitude under ; Negative sequence frequency The current noise amplitude under ; Negative sequence coupling frequency The current noise amplitude under ; Positive sequence frequency Positive sequence voltage noise-signal ratio under ; Negative sequence frequency Negative sequence voltage noise-to-signal ratio under ; Positive sequence frequency Positive sequence current noise-signal ratio under ; Negative sequence frequency Negative sequence current noise-to-signal ratio under .

6. The evaluation method according to claim 4, wherein: The relative error expression of the uncompensated inversion method measurement includes: Where, is the positive sequence coupling frequency Positive sequence voltage noise-signal ratio under ; Negative sequence coupling frequency Negative sequence voltage noise-to-signal ratio under ; is the positive sequence coupling frequency Positive sequence current noise-signal ratio under ; Negative sequence coupling frequency Negative sequence current noise-to-signal ratio under ; 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 equipment side; is the theoretical relative error of the SISO positive-sequence-negative-sequence coupling admittance on the equipment side; is the theoretical relative error of the SISO negative-sequence-positive-sequence coupling admittance on the equipment side; is the theoretical relative error of the SISO positive sequence impedance on the equipment side; is the theoretical relative error of the SISO negative sequence impedance on the equipment side; is the theoretical relative error of the SISO positive-sequence-negative-sequence coupling impedance on the equipment side; is the theoretical relative error of the SISO negative-sequence-positive-sequence coupling impedance on the equipment side.

7. The evaluation method according to claim 1, wherein: 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 measurement , SISO positive-sequence-negative-sequence coupling admittance The relative error of measurement , SISO negative sequence admittance The relative error of measurement , SISO negative-sequence-positive-sequence coupling admittance The relative error of measurement ; The relative error of impedance measurement includes SISO positive sequence impedance The relative error of measurement , SISO positive-sequence-negative sequence coupling impedance The relative error of measurement , SISO negative sequence impedance The relative error of measurement , SISO negative-sequence-positive-sequence coupling impedance The relative error of measurement .

8. The evaluation method according to claim 7, wherein: The relative error expression of measurement 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 numerator modulus value and the denominator modulus value. When there are two complex variables involved in the combined calculation in a numerator modulus value or a denominator modulus value, the steps of calculating the probability distribution of the numerator modulus value or the denominator modulus value include: S401. Define two complex variables as and ,set up The amplitude distribution range is ,set up The amplitude distribution range is , let vector and modulus be ,calculate The total probability distribution of: Where, is the conditional probability density function, and its expression is: ； for Probability distribution in the i-th amplitude interval; for The probability distribution in the jth amplitude interval; I is the indicator function, and its expression is: ； When there are three complex variables involved in the combined calculation of a numerator modulus or denominator modulus, first use two complex variables to execute step S401, 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 or denominator modulus.

10. An impedance / admittance measurement error evaluation system, characterized in that: Used to implement the evaluation method according to any one of claims 1 to 9, comprising: The data acquisition and calculation module is used to collect noise signals of the target device at different frequencies and calculate the probability distribution of the noise amplitude at each frequency; The frequency sweep measurement module is used to perform frequency sweep measurement on the target device to obtain the amplitude of the frequency sweep response signal at each frequency; Noise-signal ratio calculation module, used to calculate the noise-signal ratio at each frequency The probability distribution of Error expression building block, used to calculate relative measurement error by inversion method or decoupling method Expressions of The module for calculating the probability distribution of modulus value is used to decompose the expression for calculating the relative error of measurement into the numerator and denominator of the expression, and calculate the modulus value of the numerator of the expression respectively. Sum expression denominator modulo value The probability distribution of Logarithmic coordinate conversion and result calculation module, used to convert the expression numerator modulus Sum expression denominator modulo value Convert to the logarithmic coordinate system and calculate the probability distribution of the measurement relative error in the logarithmic coordinate system.

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