A method for compressing and transmitting harmonic data of a three-phase electric energy meter

Abstract

The present application belongs to the technical field of electric power data processing, and provides a kind of compression transmission method of three-phase electric energy meter harmonic data: when discrete fourier transform+quantization encoding compression three-phase electric energy meter harmonic data, the screening of electric energy meter harmonic is carried out;The relevance between quantization step and the amplitude error of electric energy meter harmonic is analyzed, in the case of linear correlation, it is judged whether the target quantization step that can meet high compression ratio and amplitude error can be found under the limitation of high compression ratio, if yes, the set quantization step is changed;If not, the quantization step analysis is carried out on the screened electric energy meter harmonic, to determine whether the source of the amplitude error of electric energy meter harmonic is the mismatch of quantization step, if yes, the key electric energy meter harmonic is locally refined quantization, and the compression ratio balance verification is carried out after quantization;If verification fails, through the combination operation of non-key harmonic redundancy pruning+key harmonic efficient coding, it is ensured that compression ratio and amplitude error are up to standard.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electric power data processing, and particularly relates to a compression transmission method for harmonic data of a three-phase electric energy meter. BACKGROUND

[0002] In the operation process of the three-phase electric energy meter, the harmonic data, as a key basis for evaluating the power grid quality, needs to be compressed effectively to realize efficient transmission and storage, and the "discrete Fourier transform (DFT) + quantization coding" is the current mainstream compression technology. However, the traditional compression scheme has obvious shortcomings: on the one hand, it is difficult to balance the compression ratio and data accuracy with a fixed quantization step, and if the step is too large, the amplitude error of the key harmonics such as 3rd and 5th, which affect the power grid quality, will exceed the requirement of "harmonic measurement error ≤ 2%" in GB / T17215.323-2022 standard, and if the step is too small, the compression efficiency will be low, increasing the storage and transmission cost; on the other hand, there is a lack of systematic analysis of the correlation between the quantization step and the amplitude error, and the parameters cannot be dynamically adjusted to balance the relationship between the two, and the key and non-key harmonic characteristics are not distinguished, so it is difficult to accurately locate the error source (such as whether the quantization step is mismatched) when the compression ratio is not up to standard, and no differentiated optimization strategy is formulated for different harmonics, resulting in insufficient adaptability and robustness of the scheme. In addition, when the compression ratio and accuracy conflict, the traditional scheme often lacks supplementary means such as redundant data pruning and efficient coding, and cannot ensure that both of them meet the standard at the same time, so it is difficult to meet the fine and efficient demand for harmonic data compression in complex power grid scenarios, and a progressive and differentiated optimization scheme is needed to solve the above problems.

[0003] Therefore, the application provides a compression transmission method for harmonic data of a three-phase electric energy meter. SUMMARY

[0004] In order to make up for the shortcomings of the prior art and solve at least one technical problem proposed in the background art.

[0005] The technical scheme adopted by the application to solve the technical problems is: a compression transmission method for harmonic data of a three-phase electric energy meter, comprising the following steps:

[0006] Step 1: When the discrete Fourier transform + quantization coding is used to compress the harmonic data of the three-phase electric energy meter, compare the amplitude error of the harmonic of the electric energy meter under the set quantization step, and select the harmonic of the electric energy meter;

[0007] Step 2: analyze the correlation between the quantization step and the amplitude error of the harmonic of the electric energy meter, and if there is a linear correlation, determine whether a target quantization step that can meet both the high compression ratio and the amplitude error can be found under the limitation of the high compression ratio, and if so, change the set quantization step according to the target quantization step;

[0008] Step three: if not, the quantization step of the screened power meter harmonic is analyzed, and it is determined whether the amplitude error source of the power meter harmonic is the mismatch of the quantization step, if yes, the key power meter harmonic is locally quantized, and the compression ratio balance verification is carried out after the local fine quantization;

[0009] Step four: if the compression ratio balance verification result fails, the non-key harmonic redundancy pruning and key harmonic efficient coding combined operation are carried out to ensure that the compression ratio and the amplitude error meet the standards.

[0010] As a further technical solution of the application, the process of screening the power meter harmonic is:

[0011] Based on any power meter harmonic, the amplitude error of the power meter harmonic is obtained;

[0012] If the amplitude error is greater than the amplitude error threshold, the power meter harmonic corresponding to the amplitude error is screened out.

[0013] As a further technical solution of the application, the process of analyzing the correlation between the quantization step and the amplitude error of the power meter harmonic is:

[0014] Based on any power meter harmonic, the amplitude error of the power meter harmonic under different historical quantization steps is obtained, and the amplitude error sequence is integrated to integrate the quantization step sequence;

[0015] The Pearson correlation coefficient between the amplitude error sequence and the quantization step sequence is calculated, and the correlation coefficient is obtained after absolute valueization;

[0016] If the correlation coefficient is greater than or equal to the correlation coefficient threshold, it indicates that there is a linear correlation between the quantization step and the amplitude error of the power meter harmonic;

[0017] If the amplitude error of all power meter harmonics is linearly correlated with the quantization step, it indicates that there is a linear correlation.

[0018] As a further technical solution of the application, the process of judging whether the target quantization step that can simultaneously satisfy the high compression ratio and the amplitude error can be found under the limitation of the high compression ratio is:

[0019] The high compression ratio is obtained, and the required quantization step of each power meter harmonic is calculated by combining the maximum amplitude of each power meter harmonic;

[0020] The maximum quantization step in the required quantization step of each power meter harmonic is selected as the minimum endpoint value, the set quantization step is selected as the maximum endpoint value, and the quantization step range is constructed;

[0021] Based on any power meter harmonic, the error of the power meter harmonic satisfies the quantization step;

[0022] If the error of all the electric energy meter harmonics meets the quantization step, it indicates that the target quantization step that can simultaneously meet the high compression ratio and the amplitude error can be found under the limitation of the high compression ratio, otherwise, it indicates that the target quantization step that can simultaneously meet the high compression ratio and the amplitude error cannot be found under the limitation of the high compression ratio.

[0023] If the target quantization step that can simultaneously meet the high compression ratio and the amplitude error can be found, the minimum error meeting quantization step is selected as the target quantization step, and the set quantization step is changed to the target quantization step.

[0024] As a further technical solution of the present application, the acquisition method of the error meeting quantization step of the electric energy meter harmonic is:

[0025] Based on any electric energy meter harmonic, the least square method is used for fitting according to the amplitude error sequence and the quantization step sequence, and a fitting model about the amplitude error-quantization step is obtained.

[0026] The amplitude error of the electric energy meter harmonic is substituted into the fitting model about the amplitude error-quantization step, and the error meeting quantization step of the electric energy meter harmonic is obtained.

[0027] As a further technical solution of the present application, the process of determining whether the source of the amplitude error of the electric energy meter harmonic is the mismatch of the quantization step is:

[0028] Based on any electric energy meter harmonic, a first error sequence and a second error sequence are obtained by setting different test quantization steps.

[0029] The Euclidean distance between the first error sequence and the second error sequence is calculated, if the Euclidean distance meets the requirement, it indicates that the source of the amplitude error of the electric energy meter harmonic is the mismatch of the quantization step, otherwise, it is not.

[0030] As a further technical solution of the present application, the acquisition method of the first error sequence and the second error sequence is:

[0031] Different test quantization steps are set, the amplitude error of the electric energy meter harmonic data under different test quantization steps is obtained, and a first error sequence is integrated.

[0032] Different test quantization steps are substituted into the fitting model about the amplitude error-quantization step, the amplitude error corresponding to different test quantization steps is obtained, and a second error sequence is integrated.

[0033] As a further technical solution of the present application, the process of performing local fine quantization on the key electric energy meter harmonic is:

[0034] According to the power grid quality influence priority, a key electric energy meter harmonic is determined in the electric energy meter harmonic;

[0035] Based on any key electric energy meter harmonic, according to the original harmonic amplitude and the harmonic measurement error of the key electric energy meter harmonic, the fine quantization step of the key electric energy meter harmonic is calculated, and the quantization step of the key electric energy meter harmonic is changed according to the fine quantization step.

[0036] As a further technical solution of the application, the process of compression ratio balance verification after local fine quantization is:

[0037] The data amount before and after the sub-sampling of the electric energy meter harmonic data is obtained, and the proportion is calculated to obtain the compression ratio;

[0038] If the compression ratio is higher than or equal to the set required high compression ratio, it means that the compression ratio balance verification is successful, otherwise, the compression ratio balance verification fails.

[0039] As a further technical solution of the application, the process of ensuring that the compression ratio and the amplitude error meet the standards through the combination of non-key harmonic redundancy pruning and key harmonic efficient coding is:

[0040] Only the amplitude information of the non-key electric energy meter harmonic is retained, the phase data is deleted, the data amount of the non-key electric energy meter harmonic is reduced, the characteristic that the amplitude of the key electric energy meter harmonic fluctuates little in a short time is utilized, the complete amplitude is stored in the first frame, and only the amplitude difference value of the previous frame is stored in the subsequent frame, the data amount of the key electric energy meter harmonic is reduced, the quantization coefficient is normalized according to the maximum amplitude of the key electric energy meter harmonic, the number of coding bits is reduced, and it is ensured that the total error after normalization is less than or equal to 2%.

[0041] The beneficial effects of the application are as follows: first, the harmonics with amplitude error exceeding the standard are screened based on the set quantization step, to ensure that the initial error of the core harmonic meets the standard; second, the linear correlation between the quantization step and the amplitude error is analyzed, and the target quantization step that takes both into account is found under the limitation of high compression ratio and is adjusted; if the target step does not exist, it is verified whether the error source is the mismatch of the quantization step, the key harmonic is locally fine quantized, and the compression ratio balance is verified; if the compression ratio still does not meet the standard, the redundant data of the non-key harmonic is pruned and the coding of the key harmonic is optimized to ensure that both meet the standard. Overall, the amplitude error of the key harmonic meets the requirement of GB / T17215.323-2022 (≤2%) through error screening, local fine quantization and standard constraints, and the precision of the core data is ensured, and the compression ratio is maximally improved through dynamic adjustment of the quantization step, correlation analysis and coding optimization. BRIEF DESCRIPTION OF DRAWINGS

[0042] The application will be further described below with reference to the drawings.

[0043] Figure 1 is a flow chart of steps of a three-phase electric energy meter harmonic data compression transmission method according to the present application;

[0044] Figure 2 is a logic judgment chart of a three-phase electric energy meter harmonic data compression transmission method according to the present application. DETAILED DESCRIPTION

[0045] In order to make the technical means, creative features, purposes and effects of the present application easy to understand, the present application is further described below in combination with specific embodiments.

[0046] Referring to Figure 1 the three-phase electric energy meter harmonic data compression transmission method according to the present application, comprises the following steps:

[0047] Step one: when the three-phase electric energy meter harmonic data is compressed by discrete Fourier transform + quantization coding, the amplitude error of the harmonic of the electric energy meter under the set quantization step is compared, and the harmonic of the electric energy meter is screened;

[0048] In step one, the set quantization step is set in advance by the technician when the three-phase electric energy meter harmonic data is compressed by "discrete Fourier transform + quantization coding";

[0049] In step one, the process of screening the harmonic of the electric energy meter is:

[0050] Based on any harmonic of the electric energy meter, the amplitude error of the harmonic of the electric energy meter is obtained and compared with the amplitude error threshold;

[0051] If the amplitude error is less than or equal to the amplitude error threshold, no operation is performed;

[0052] If the amplitude error is greater than the amplitude error threshold, the harmonic of the electric energy meter corresponding to the amplitude error is screened out, and the screening is completed;

[0053] In step one, the amplitude error of the harmonic of the electric energy meter is obtained in the following way:

[0054] The original signal (current / voltage signal) of the three-phase electric energy meter sampled by high-precision AD (such as 16-bit or 24-bit sampling) is obtained, the original signal is calculated by DFT (such as the amplitude of each harmonic of 3 times, 5 times, 7 times, etc. of the fundamental wave 50Hz), and the original harmonic amplitude A 原始 is obtained.

[0055] The original harmonic amplitude is quantized by the set quantization step to obtain the quantized harmonic amplitude, the error A 量化 between the original harmonic amplitude and the quantized harmonic amplitude is calculated, the amplitude error is obtained, and the specific calculation formula is:

[0056] ;

[0057] It should be noted that the amplitude error threshold is 5%, which is set according to the requirement of "harmonic measurement error ≤ 2%" in GB / T17215.323-2022 "Special Requirements for AC Electric Measurement Equipment Part 23: Static Active Power Meter (0.2S and 0.5S)", it can be understood that if the quantization step is too large, the amplitude error of 3rd and 5th harmonics (the main harmonics affecting the quality of power grid) will exceed 5%, which does not meet the requirement of "harmonic measurement error ≤ 2%" in GB / T17215.323-2022 "Special Requirements for AC Electric Measurement Equipment Part 23: Static Active Power Meter (0.2S and 0.5S)";

[0058] It can be understood that the role of step one is to set the quantization step, calculate and compare the amplitude error of each harmonic with the threshold, and select the harmonics with error exceeding the standard, which is to preliminarily ensure that the amplitude error of key harmonics (such as 3rd and 5th harmonics) in the compressed harmonic data after "discrete Fourier transform + quantization coding" meets the requirements of GB / T17215.323-2022 standard, and provides a basic screening result for subsequent compression optimization, to ensure the accuracy of core harmonic data;

[0059] Step two: analyze the correlation between the quantization step and the amplitude error of the electric energy meter harmonics, if there is a linear correlation, determine whether a target quantization step that can meet both high compression ratio and amplitude error can be found under the limitation of high compression ratio, if so, change the set quantization step according to the target quantization step;

[0060] In step two, the process of analyzing the correlation between the quantization step and the amplitude error of the electric energy meter harmonics is as follows:

[0061] Based on any electric energy meter harmonics, obtain the amplitude error of the electric energy meter harmonics under different historical quantization steps, and integrate to obtain an amplitude error sequence, and integrate different historical quantization steps into a quantization step sequence;

[0062] It should be noted that the amplitude error sequence is obtained by integrating the amplitude error of different electric energy meter harmonics under different quantization steps in the past historical compression transmission process;

[0063] Calculate the Pearson correlation coefficient between the amplitude error sequence and the quantization step sequence, and obtain the correlation coefficient after absolute value;

[0064] If the correlation coefficient is greater than or equal to the correlation coefficient threshold, it indicates that there is a linear correlation between the quantization step and the amplitude error of the electric energy meter harmonics;

[0065] If the correlation coefficient is less than the correlation coefficient threshold, it indicates that there is no linear correlation between the quantization step and the amplitude error of the power meter harmonic;

[0066] If the amplitude error of all power meter harmonics is linearly correlated with the quantization step, it indicates that there is linear correlation;

[0067] If the amplitude error of all power meter harmonics is not linearly correlated with the quantization step or is not uniformly linearly correlated, it indicates that there is no linear correlation;

[0068] In step two, the process of determining whether a target quantization step that can simultaneously satisfy the high compression ratio and the amplitude error can be found under the limitation of the high compression ratio is as follows:

[0069] The high compression ratio is obtained, and the required quantization step of each power meter harmonic is calculated in combination with the maximum amplitude of each power meter harmonic, and the specific calculation is as follows:

[0070] ;

[0071] Wherein, CR is the high compression ratio, Amax is the maximum amplitude of each power meter harmonic, is the required quantization step of each power meter harmonic;

[0072] For example, taking the 3rd harmonic (Amax=20A) as an example:

[0073] When =0.5A, the compression ratio CR=32 / 6=5.3:1;

[0074] When =1A, the compression ratio CR=32 / 5=6.4:1;

[0075] When =2A, the compression ratio CR=32 / 4=8:1;

[0076] When =4A, the compression ratio CR=32 / 3=10.7:1;

[0077] The maximum quantization step in the required quantization step of each power meter harmonic is selected as the minimum endpoint value, the set quantization step is selected as the maximum endpoint value, and the quantization step range is constructed;

[0078] It should be noted that the quantization step and the compression ratio are positively correlated, so the maximum quantization step in the required quantization step is selected as the minimum endpoint value, and the purpose is to find a quantization step that can satisfy the amplitude error requirement of each power meter harmonic within the limited range of the high compression ratio, and the maximum quantization step in the required quantization step is less than the set quantization step;

[0079] According to the amplitude error sequence and the quantization step sequence, and by using the least square method, a fitting model about the amplitude error-quantization step is obtained based on any one of the electric energy meter harmonics;

[0080] It should be noted that the amplitude error and the quantization step are linearly related, and therefore, the least square method is used for fitting. It should also be noted that each electric energy meter harmonic has a fitting model about the amplitude error-quantization step;

[0081] The amplitude error of the electric energy meter harmonic is substituted into the fitting model about the amplitude error-quantization step to obtain an error satisfying quantization step of the electric energy meter harmonic based on any one of the electric energy meter harmonics;

[0082] The error satisfying quantization step of each electric energy meter harmonic is compared with the quantization step range;

[0083] If the error satisfying quantization step of all electric energy meter harmonics is within the quantization step range, it indicates that a target quantization step that can simultaneously satisfy the high compression ratio and the amplitude error can be found under the limitation of the high compression ratio;

[0084] If the target quantization step that can simultaneously satisfy the high compression ratio and the amplitude error can be found, the minimum error satisfying quantization step is selected as the target quantization step, and the set quantization step is changed to the target quantization step;

[0085] If the error satisfying quantization step of all electric energy meter harmonics is not within the quantization step range, it indicates that a target quantization step that can simultaneously satisfy the high compression ratio and the amplitude error cannot be found under the limitation of the high compression ratio;

[0086] It can be understood that the error satisfying quantization step represents the quantization step required by the electric energy meter harmonic data compression to satisfy the amplitude error requirement, and the quantization step range is constructed according to the requirement of the high compression ratio. If the error satisfying quantization step of all electric energy meter harmonics is within the quantization step range, it indicates that a quantization step that can satisfy both the amplitude error and the high compression ratio can be found;

[0087] It can be understood that the function of step two is to analyze the linear relationship between the quantization step and the amplitude error, construct the quantization step range combined with the limitation of the high compression ratio, find the target quantization step by using the fitting model, and adjust the set value. Its function is to improve the data compression ratio as much as possible under the premise of ensuring the amplitude error to meet the standard, and to balance the compression efficiency and data accuracy;

[0088] Step three: if not, perform quantization step analysis on the screened electric energy meter harmonics to determine whether the amplitude error source of the electric energy meter harmonics is the mismatch of quantization step, if so, perform local fine quantization on the key electric energy meter harmonics, and perform compression ratio balance verification after local fine quantization;

[0089] In step three, the process of determining whether the amplitude error source of the electric energy meter harmonics is the mismatch of quantization step by performing quantization step analysis on the screened electric energy meter harmonics is as follows:

[0090] Based on any electric energy meter harmonic, set different test quantization steps (such as 1 / 2, 1 / 3, etc. of the set quantization step), obtain the amplitude error of the electric energy meter harmonic data under different test quantization steps, and integrate to obtain a first error sequence;

[0091] Substitute different test quantization steps into the fitting model of amplitude error-quantization step to obtain the amplitude error corresponding to different test quantization steps, and integrate to obtain a second error sequence;

[0092] It can be understood that the first error sequence obtained by substituting different test quantization steps into the fitting model of amplitude error-quantization step contains the theoretical amplitude error corresponding to different quantization steps (in the case of amplitude error source being the mismatch of quantization step), while the amplitude error of the electric energy meter harmonic under different test quantization steps is the actual amplitude error. The deviation between the actual amplitude error and the theoretical amplitude error can reflect whether the amplitude error source of the electric energy meter harmonic is the mismatch of quantization step;

[0093] Calculate the Euclidean distance between the first error sequence and the second error sequence, and compare it with the Euclidean distance threshold;

[0094] If the Euclidean distance is greater than the Euclidean distance threshold, it means that the amplitude error source of the electric energy meter harmonic is not the mismatch of quantization step, then analyze other amplitude error sources, including but not limited to phase deviation, etc.

[0095] If the Euclidean distance is less than or equal to the Euclidean distance threshold, it means that the amplitude error source of the electric energy meter harmonic is the mismatch of quantization step;

[0096] In step three, the process of performing local fine quantization on the key electric energy meter harmonics is as follows:

[0097] Determine the key electric energy meter harmonics in the electric energy meter harmonics according to the grid quality influence priority (such as the key requirements of GB / T17215.323-2022 for harmonic monitoring);

[0098] Based on any key electric energy meter harmonic, according to the original harmonic amplitude A 原始And harmonic measurement error (2%), calculate the fine quantization step of key electric energy meter harmonic 精细 ; The specific calculation formula is:

[0099] ;

[0100] ;

[0101] For key electric energy meter harmonics, according to the fine quantization step 精细 Change the set quantization step of key electric energy meter harmonics;

[0102] In step three, the process of compression ratio balance verification after local fine quantization is:

[0103] Get the data amount of electric energy meter harmonic data before and after sub-sampling and calculate the proportion to get the compression ratio;

[0104] For example, the calculation method of compression ratio is: Assuming the scene: total harmonics are 10 times (2 times of key electric energy meter harmonics + 8 times of non-key electric energy meter harmonics (priority is determined by power grid quality)), original data is 4 bytes / time (floating point type), and quantization is coded in binary (bit number is determined by step length):

[0105] Key electric energy meter harmonics (2 times): original step length Δ = 0.5A, 6 bits / time, after fine quantization Δ = 0.4A, 7 bits / time (because the quantization level increases), total bits = 2x7 = 14 bits; Non-key electric energy meter harmonics (8 times): step length Δ = 0.5A, 6 bits / time, total bits = 8x6 = 48 bits;

[0106] Total data amount after compression = (14+48):8 = 62:8 = 7.75 bytes (1 byte = 8 bits);

[0107] Original total data amount = 10 times x 4 bytes = 40 bytes, compression ratio = 40:7.75x = 5.16:1;

[0108] If the compression ratio is higher than or equal to the set high compression ratio, it means that the compression ratio balance verification is successful, and no operation is performed;

[0109] If the compression ratio is lower than the set high compression ratio, it means that the compression ratio balance verification fails;

[0110] Understandably, the purpose of step three is to: analyze the source of error by testing the quantization step size when a target quantization step size that meets the requirements cannot be found, perform local fine quantization of the key harmonics and verify the compression ratio balance. Its purpose is to solve the error problem caused by the mismatch of quantization step size. While ensuring the measurement accuracy of the key harmonics, it attempts to maintain a high compression ratio through local adjustments to avoid the overall compression effect from deteriorating.

[0111] Step 4: If the compression ratio balance verification fails, then the compression ratio and amplitude error are ensured to meet the standards by combining non-critical harmonic redundancy trimming with critical harmonic efficient coding.

[0112] In step four, the process of ensuring that both the compression ratio and amplitude error meet the standards through the combination of non-critical harmonic redundancy trimming and critical harmonic efficient coding is as follows:

[0113] Only the amplitude information of harmonics (such as the 7th order and above) of non-critical energy meters is retained, and phase data is deleted (phase has a very small impact on power grid quality assessment), reducing the amount of harmonic data of non-critical energy meters by about 50%. Taking advantage of the small fluctuation of harmonic amplitude in a short period of time of critical energy meters, the first frame stores the complete amplitude, and subsequent frames only store the amplitude difference with the previous frame, reducing the amount of harmonic data of critical energy meters. The quantization coefficient is normalized according to the maximum amplitude of the harmonics of critical energy meters, reducing the number of bits in the encoding, and ensuring that the total error after normalization is ≤2%.

[0114] For example, non-critical harmonic redundancy reduction: for the 7th, 9th, and 11th harmonics, only amplitude information (2 bytes) is retained, and phase data (2 bytes) is deleted. The data size of a single non-critical harmonic group is reduced from 4 bytes / harmonic to 2 bytes / harmonic, and the total data size of the 3rd non-critical harmonic is reduced by 50% (from 12 bytes to 6 bytes). The first frame of the 3rd harmonic stores the complete amplitude (20A), and subsequent frames only store the difference from the previous frame (e.g., fluctuation range ±1A, which can be represented by 1 byte). The same applies to the 5th harmonic, where the first frame stores 15A, and subsequent frames store the difference. (±0.8A, 1 byte representation), reducing data volume by 50% compared to the original 4 bytes / harmonic; normalization of quantization coefficients for key harmonics: for the 3rd harmonic, with the maximum amplitude of 20A as the baseline, the number of bits in the encoding is increased from 6 bits (step size 0.5A) to 5 bits (step size 0.625A) after normalization, with an error of <1.5% (≤2%); for the 5th harmonic, with 15A as the baseline, the number of bits in the encoding is reduced from 5 bits (step size 0.5A) to 4 bits (step size 0.9375A) after normalization, with an error of ≤1.25% (≤2%).

[0115] It is understandable that the purpose of step four is to combine non-critical harmonic redundancy pruning with critical harmonic efficient coding when the compression ratio balance verification fails. Its purpose is to reduce the amount of non-critical data and optimize the coding method of critical data, thereby effectively improving the overall compression ratio while ensuring that the amplitude error meets the standard. Ultimately, it achieves the dual standard of compression ratio and amplitude error, ensuring the effectiveness and reliability of harmonic data compression transmission.

[0116] The technical solution and advantages of this application are as follows: First, based on a set quantization step size, harmonics with excessive amplitude errors are screened out to ensure that the initial error of the core harmonics meets the standard; then, the linear correlation between the quantization step size and the amplitude error is analyzed, and a target quantization step size that balances both is found and adjusted under the constraint of high compression ratio; if the target step size does not exist, the source of error is verified by testing to see if it is a quantization step size mismatch, and local fine quantization is performed on the key harmonics to verify the compression ratio balance; if the compression ratio still does not meet the standard, redundant data of non-key harmonics is trimmed and the key harmonic coding is optimized to ensure that both standards are met. In terms of overall technical effect, the key harmonic amplitude error meets the requirements of GB / T17215.323-2022 (≤2%) through error screening, local fine quantization, and standard constraints, ensuring the accuracy of core data, and the compression ratio is maximized through dynamic adjustment of the quantization step size, correlation analysis, and coding optimization.

[0117] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for compressing and transmitting harmonic data from a three-phase energy meter, characterized in that: Includes the following steps: Step 1: When compressing the harmonic data of three-phase electricity meters using Discrete Fourier Transform + Quantization encoding, compare the amplitude error of the harmonics of the electricity meters under the set quantization step size to screen the harmonics of the electricity meters. Step 2: Analyze the correlation between the quantization step size and the amplitude error of the energy meter harmonics. If there is a linear correlation, determine whether a target quantization step size can be found that simultaneously satisfies both the high compression ratio and the amplitude error under the constraint of high compression ratio. If so, modify the set quantization step size according to the target quantization step size. Step 3: If not, perform quantization step size analysis on the screened electricity meter harmonics to determine whether the source of the amplitude error of the electricity meter harmonics is quantization step size mismatch. If so, perform local fine quantization on the key electricity meter harmonics and perform compression ratio balance verification after local fine quantization. Step 4: If the compression ratio balance verification fails, then the compression ratio and amplitude error are ensured to meet the standards by combining non-critical harmonic redundancy trimming with critical harmonic efficient coding.

2. The method for compressing and transmitting harmonic data of a three-phase energy meter according to claim 1, characterized in that: The process of screening harmonics in electricity meters is as follows: Based on any harmonic of the electricity meter, obtain the amplitude error of the harmonic of the electricity meter; If the amplitude error is greater than the amplitude error threshold, then the harmonics of the electricity meter corresponding to the amplitude error are selected.

3. The method for compressing and transmitting harmonic data of a three-phase energy meter according to claim 2, characterized in that: The process of analyzing the correlation between the quantization step size and the amplitude error of the harmonics in the energy meter is as follows: Based on any harmonic of the electricity meter, the amplitude error of the harmonic of the electricity meter under different historical quantization step sizes is obtained, and the amplitude error sequence is integrated to obtain the amplitude error sequence. The different historical quantization step sizes are integrated into the quantization step size sequence. Calculate the Pearson correlation coefficient between the amplitude error sequence and the quantization step size sequence, and obtain the correlation coefficient after absolute value conversion; If the correlation coefficient is greater than or equal to the correlation coefficient threshold, it indicates that there is a linear correlation between the quantization step size and the amplitude error of the harmonics of the electricity meter. If the amplitude error of all electricity meter harmonics is linearly correlated with the quantization step size, then it indicates that there is a linear correlation.

4. The method for compressing and transmitting harmonic data of a three-phase energy meter according to claim 3, characterized in that: The process of determining whether a target quantization step size that can simultaneously satisfy both high compression ratio and amplitude error can be found under the constraint of high compression ratio is as follows: A high compression ratio is obtained, and the required quantization step size of each energy meter's harmonics is calculated by combining the maximum amplitude of each energy meter's harmonics. The maximum quantization step size among the required quantization step sizes for harmonics of each energy meter is selected as the minimum endpoint value, and the set quantization step size is used as the maximum endpoint value to construct the quantization step size range. Based on any harmonic of the electricity meter, the error of the electricity meter harmonic is obtained to satisfy the quantization step size; If the errors of all energy meter harmonics are within the range of the quantization step size, it means that a target quantization step size that can simultaneously satisfy both high compression ratio and amplitude error can be found under the constraint of high compression ratio. Conversely, it means that a target quantization step size that can simultaneously satisfy both high compression ratio and amplitude error cannot be found under the constraint of high compression ratio. If a target quantization step size that can simultaneously satisfy both high compression ratio and amplitude error can be found, then the quantization step size that satisfies the minimum error is selected as the target quantization step size, and the previously set quantization step size is changed to the target quantization step size.

5. The method for compressing and transmitting harmonic data of a three-phase energy meter according to claim 4, characterized in that: The method for obtaining the quantization step size for the harmonic error of the electricity meter is as follows: Based on any harmonic of the electricity meter, according to the amplitude error sequence and the quantization step sequence, and by fitting with the least squares method, a fitting model for amplitude error-quantization step is obtained. Substituting the amplitude error of the electricity meter harmonics into the fitting model of amplitude error-quantization step size, we find that the harmonic error of the electricity meter satisfies the quantization step size.

6. The method for compressing and transmitting harmonic data of a three-phase energy meter according to claim 5, characterized in that: The process of performing quantization step size analysis on the harmonics of the screened electricity meters to determine whether the amplitude error of the electricity meter harmonics is caused by quantization step size mismatch is as follows: Based on any harmonic of the electricity meter, by setting several different test quantization step sizes, the first error sequence and the second error sequence are obtained; Calculate the Euclidean distance between the first error sequence and the second error sequence. If the Euclidean distance meets the requirements, it indicates that the source of the harmonic amplitude error of the electricity meter is the quantization step size mismatch; otherwise, it is not.

7. The method for compressing and transmitting harmonic data of a three-phase energy meter according to claim 6, characterized in that: The first and second error sequences are obtained as follows: Set several different test quantization step sizes, obtain the amplitude error of the harmonic data of the energy meter under different test quantization step sizes, and integrate them to obtain the first error sequence; By substituting different test quantization step sizes into the amplitude error-quantization step size fitting model, the amplitude error corresponding to different test quantization step sizes is obtained, and then integrated to obtain the second error sequence.

8. The method for compressing and transmitting harmonic data of a three-phase energy meter according to claim 7, characterized in that: The process of local fine-grained quantization of harmonics in key energy meters is as follows: Based on the priority of the impact on power grid quality, the key energy meter harmonics are identified in the energy meter harmonics. Based on any key energy meter harmonic, the fine quantization step size of the key energy meter harmonic is calculated according to the original harmonic amplitude and harmonic measurement error. For the key energy meter harmonic, the set quantization step size of the key energy meter harmonic is changed according to the fine quantization step size.

9. A method for compressing and transmitting harmonic data of a three-phase energy meter according to claim 8, characterized in that: The process of performing compression ratio balancing verification after local fine-grained quantization is as follows: The amount of harmonic data from the electricity meter before and after Yaso is obtained and the ratio is calculated to obtain the compression ratio. If the compression ratio is higher than or equal to the set high compression ratio, the compression ratio balance verification is successful; otherwise, the compression ratio balance verification fails.

10. A method for compressing and transmitting harmonic data of a three-phase energy meter according to claim 9, characterized in that: The process of ensuring that both compression ratio and amplitude error meet the standards through a combination of non-critical harmonic redundancy trimming and efficient encoding of critical harmonics is as follows: Only the amplitude information of harmonics from non-critical energy meters is retained, while phase data is deleted to reduce the amount of harmonic data from non-critical energy meters. Taking advantage of the small fluctuation of harmonic amplitude in critical energy meters over a short period of time, the complete amplitude is stored in the first frame, and subsequent frames only store the amplitude difference with the previous frame, thus reducing the amount of harmonic data from critical energy meters. The quantization coefficients are normalized according to the maximum amplitude of the harmonics from critical energy meters to reduce the number of bits in the encoding and ensure that the total error after normalization is ≤2%.

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