A method for compensating DC even-order harmonic errors in electric energy meters

Abstract

This application discloses a method for compensating for DC even-order harmonic errors in electricity meters. The method includes: using the least squares method to fit a curve of the relationship between error and current to obtain a functional relationship between error and current; reading the current test current value and correcting it; fitting an error value based on the corrected current value and the obtained functional relationship between error and current; calculating the phase angle offset or power compensation value using the fitted error value; and compensating for the DC even-order harmonics accordingly based on the calculated phase angle offset or power compensation value. This method yields more accurate results and improves the compensation effect.

Description

Technical Field

[0001] The invention relates to the field of electric power equipment, and in particular to a method for compensating direct current even-order harmonic errors of electric energy meters. Background Art

[0002] In the detection of electric energy meters, the harmonic error test is used as an assessment item, mainly to examine whether the smart meter can ensure the accuracy of measurement when there are harmonic contents in the voltage or current circuit. The purpose of the DC even harmonic influence experiment is to detect whether the electric energy meter can accurately measure when the current circuit contains DC components and even harmonics. This is also an experiment to assess the measurement accuracy.

[0003] In smart meters, the transformer is used as the current sampling device of the energy meter. When the current waveform is a DC even harmonic, the transformer used in the three-phase meter cannot pass DC, resulting in phase deviation. Therefore, in order to accurately measure, it is necessary to compensate for the DC even harmonic.

[0004] At present, for DC even harmonic compensation, the compensation method used in the metering chip manual is: first obtain the current value, use Figure 1 The segmented customization method shown divides the current into intervals and takes the error corresponding to the current in each interval as a constant value, or uses Figure 2 The linear compensation method shown replaces the functional relationship between current and error with a straight line, and solves the error with a linear function; then the compensation amount is calculated by approximate calculation method through the error, and then the compensation amount is used to compensate the DC even harmonics. However, the results obtained by these methods have large deviations. In the case of large phase angles or errors, the approximate solution in the calculation will no longer hold, and the approximate error will be relatively large, resulting in inaccurate results after compensation. Summary of the invention

[0005] In view of this, the purpose of the present invention is to provide a method for compensating for DC even harmonic errors of an electric energy meter, which can obtain a more accurate compensation result. The specific scheme is as follows:

[0006] A method for compensating direct current even harmonic errors of an electric energy meter, comprising:

[0007] The relationship between the error and the current is fitted by the least square method to obtain the functional relationship between the error and the current;

[0008] Reading the current test current value and correcting the current test current value;

[0009] Fitting the error value according to the corrected current value and the obtained functional relationship between the error and the current;

[0010] Calculate the phase angle offset or power compensation value using the fitted error value;

[0011] According to the calculated phase angle offset or power compensation value, the DC even harmonics are compensated accordingly.

[0012] Preferably, in the above-mentioned electric energy meter DC even harmonic error compensation method provided by the embodiment of the present invention, the least square method is used to perform curve fitting on the relationship between the error and the current to obtain the functional relationship between the error and the current, including:

[0013] Test and record the initial error values ​​corresponding to different initial currents without compensation;

[0014] The least square method is used to fit the relationship between the error and the current, and the functional relationship between the error and the current is fitted;

[0015] Substituting the recorded initial current and initial error value into the fitted functional relationship, and determining each coefficient in the fitted functional relationship by Gaussian elimination method;

[0016] Substitute the determined coefficients into the fitted functional relationship to obtain a functional relationship containing only the error and the current.

[0017] Preferably, in the above-mentioned electric energy meter DC even harmonic error compensation method provided by the embodiment of the present invention, the correction of the current test current value includes:

[0018] Obtain the current correction multiple according to the actual measured value and theoretical value of the current;

[0019] The current test current value is corrected according to the current correction multiple.

[0020] Preferably, in the above-mentioned electric energy meter DC even harmonic error compensation method provided by the embodiment of the present invention, the step of calculating the phase angle offset by using the fitted error value includes:

[0021] Obtaining the functional mapping relationship between phase angle offset, phase angle and error;

[0022] The phase angle offset is calculated based on the fitted error value and the known phase angle, as well as the acquired functional mapping relationship between the phase angle and the error.

[0023] Preferably, in the above-mentioned electric energy meter DC even harmonic error compensation method provided by the embodiment of the present invention, the expression of the functional mapping relationship between the phase angle offset, the phase angle and the error is:

[0024]

[0025] in, Indicates the phase angle offset; Represents the phase angle; Error represents the fitted error value.

[0026] Preferably, in the above-mentioned electric energy meter DC even harmonic error compensation method provided by the embodiment of the present invention, the DC even harmonics are compensated accordingly according to the calculated phase angle offset, including:

[0027] Convert the calculated phase angle offset into a phase correction register value;

[0028] The DC even harmonics are compensated accordingly through the phase correction register value.

[0029] Preferably, in the above-mentioned electric energy meter DC even harmonic error compensation method provided by the embodiment of the present invention, the step of calculating the power compensation value by using the fitted error value includes:

[0030] Obtaining the functional mapping relationship between power compensation value, phase angle and error;

[0031] The power compensation value is calculated based on the fitted error value and the known phase angle, and the acquired functional mapping relationship between the power compensation value, the phase angle and the error.

[0032] Preferably, in the above-mentioned electric energy meter DC even harmonic error compensation method provided by the embodiment of the present invention, the expression of the function mapping relationship between the power compensation value, the phase angle and the error is:

[0033]

[0034] Where, λ represents the power compensation value; Represents the phase angle; Error represents the fitted error value.

[0035] Preferably, in the above-mentioned DC even harmonic error compensation method of the electric energy meter provided by the embodiment of the present invention, the DC even harmonics are compensated accordingly according to the calculated power compensation value, including:

[0036] The product of the calculated power compensation value and the reactive energy before compensation is added to the active energy before compensation to obtain the active energy after compensation.

[0037] The DC even harmonics are compensated accordingly by means of the compensated active power value.

[0038] Preferably, in the above-mentioned electric energy meter DC even harmonic error compensation method provided by the embodiment of the present invention, after the fitting error value, it also includes:

[0039] According to different error values ​​obtained by different mutual inductors under the same current, an error offset is obtained;

[0040] The error value obtained by fitting is corrected using the error offset.

[0041] It can be seen from the above technical scheme that a method for compensating DC even harmonic errors of an electric energy meter provided by the present invention includes: using the least squares method to perform curve fitting on the relationship between the error and the current to obtain a functional relationship between the error and the current; reading the current test current value and correcting the current test current value; fitting the error value according to the corrected current value and the obtained functional relationship between the error and the current; using the fitted error value, calculating the phase angle offset or the power compensation value; and according to the calculated phase angle offset or the power compensation value, performing corresponding compensation for the DC even harmonics.

[0042] The above-mentioned DC even harmonic error compensation method of the electric energy meter provided by the present invention first uses curve fitting to obtain the functional relationship between the error and the current, and fits the error value in combination with the test current value, and then uses the error value to calculate the phase angle offset or the power compensation value for compensation, which can obtain more accurate results and improve the compensation effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the drawings required for use in the embodiments or related technical descriptions are briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0044] Figure 1 This is the effect diagram obtained by using the existing segmented value method;

[0045] Figure 2 This is the effect diagram obtained by using the existing linear compensation method;

[0046] Figure 3 A flow chart of a method for compensating for DC even harmonic errors in an electric energy meter provided by an embodiment of the present invention;

[0047] Figure 4 A wiring diagram for a DC even harmonic experiment provided by an embodiment of the present invention;

[0048] Figure 5 for Figure 4 Schematic diagram of current waveform;

[0049] Figure 6 A specific flow chart of a method for compensating for DC even harmonic errors in an electric energy meter provided by an embodiment of the present invention;

[0050] Figure 7 A third-order polynomial fitting effect diagram provided by an embodiment of the present invention;

[0051] Figure 8 The effect diagram of the curve fitting provided by the embodiment of the present invention and the existing straight line fitting;

[0052] Fig. 9 A schematic diagram of current offset provided by an embodiment of the present invention;

[0053] Fig.10 A schematic diagram of error offset of different mutual inductors provided in an embodiment of the present invention;

[0054] Fig.11 A schematic diagram of the relationship between a compensated error value and a current value corresponding to an electric energy meter provided in an embodiment of the present invention;

[0055] Fig.12 A schematic diagram of the relationship between the compensated error value and the current value corresponding to six different electric energy meters provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0056] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0057] The present invention provides a method for compensating DC even harmonic errors of an electric energy meter. Figure 3 As shown, the following steps are included:

[0058] S101, using the least square method to perform curve fitting on the relationship between the error and the current, to obtain a functional relationship between the error and the current;

[0059] In the present invention, the functional relationship between current and error can be Error = a0 + a1I + a2I 2 +a3I 3 , where Error is the error value, I is the current value, and a0, a1, a2, and a3 all represent coefficients;

[0060] S102, reading the current test current value, and correcting the current test current value;

[0061] S103, fitting the error value according to the corrected current value and the obtained functional relationship between the error and the current;

[0062] S104, calculating a phase angle offset or a power compensation value using the fitted error value;

[0063] S105. Compensate the DC even harmonics accordingly according to the calculated phase angle offset or power compensation value.

[0064] In the above-mentioned DC even harmonic error compensation method of the electric energy meter provided in the embodiment of the present invention, the functional relationship between the error and the current is firstly fitted by using a curve, and the error value is fitted in combination with the test current value, and then the error value is used to calculate the phase angle offset or the power compensation value for compensation, so as to obtain more accurate results and improve the compensation effect.

[0065] It should be noted that Figure 4 The figure shows the wiring diagram for the DC even harmonic experiment. Figure 5 It can be seen that the current waveform used in the DC even harmonic experiment of the present invention is a half-wave waveform. The reason why the current waveform used in the DC even harmonic experiment is a half-wave waveform is that after the half-wave waveform is decomposed by the Fourier series, it can be regarded as the superposition of the DC component, the sine component, and the even harmonic component.

[0066] Half-wave Fourier decomposition:

[0067]

[0068] Therefore, from the perspective of experimental conditions, the half-wave rectification method is much simpler than the experimental DC component and even-order harmonic components, which greatly reduces the difficulty of DC even-order harmonic experiments.

[0069] In specific implementation, in the above-mentioned DC even harmonic error compensation method of the electric energy meter provided in an embodiment of the present invention, step S101 uses the least squares method to perform curve fitting on the relationship between the error and the current to obtain a functional relationship between the error and the current, which may specifically include: first, testing and recording the initial error value corresponding to different initial currents when not compensated; then, using the least squares method to perform curve fitting on the relationship between the error and the current to fit a functional relationship between the error and the current; then, substituting the recorded initial current and initial error value into the fitted functional relationship, and determining the coefficients in the fitted functional relationship by Gaussian elimination method; finally, substituting the determined coefficients into the fitted functional relationship to obtain a functional relationship containing only the error and the current.

[0070] Specifically, Figure 6 As shown, turn off the DC even harmonic error compensation function and test the initial error without compensation. Use the HPU-1510 DC even harmonic generator to output a half-wave waveform. The wiring method of the experiment is as follows: Figure 4 As shown, the initial error values ​​corresponding to different initial currents are recorded.

[0071] The error record table can be as follows:

[0072]

[0073] In the DC even-order harmonic error fitting of three-phase electric energy meters, a third-order polynomial can be used for curve fitting.

[0074] The least squares polynomial curve fitting is based on the given n points (x i ,y i ), find the approximate curve y = f(x). And make the deviation between the approximate curve and the true value as small as possible. The function expression is:

[0075] y=a0+a1x+a2x 2 +a3x 3

[0076] The purpose of the polynomial quasi-algorithm is to solve the coefficient matrix of each order

[0077] a=[a0,a1,a2,a3]

[0078] The deviation of the approximate curve at each sample point is:

[0079] y i -y=y i -f(x i )

[0080] When the sum of squares of all point deviations is minimized, the coefficient matrix can be obtained:

[0081]

[0082] According to the method of finding extreme values ​​of multiple unknown variables, the partial derivatives of each term of a are calculated. The error is minimum when the partial derivative is equal to 0:

[0083]

[0084] The coefficient a is placed on the left side of the equation:

[0085]

[0086] Write the formula in matrix form:

[0087]

[0088] Finally, the coefficient matrix a can be obtained by Gaussian elimination method.

[0089] According to the above process, the recorded initial current and initial error value are substituted into the fitted functional relationship Error = a0 + a1I + a2I 2 +a3I 3 It is used for fitting and solving the coefficient matrix a=[a0, a1, a2, a3]. The solved coefficient matrix a=[a0, a1, a2, a3] can then be stored in EEPROM and used for calculation when performing DC even-order error compensation.

[0090] Figure 7 A third-order polynomial fitting effect diagram is shown. Figure 8 The effect diagram of the curve fitting of the present invention and the existing straight line fitting is shown. It can be seen that in terms of error fitting problem, the fitting effect of the curve is better than that of the straight line.

[0091] In specific implementation, in the above-mentioned electric energy meter DC even harmonic error compensation method provided in an embodiment of the present invention, step S102 corrects the current test current value, which may specifically include: obtaining a current correction multiple based on the actual measured value and theoretical value of the current; and correcting the current test current value based on the current correction multiple.

[0092] It is important to understand that Fig. 9 The current offset problem is shown, and the current correction multiple can be obtained according to the actual measured value and theoretical value of the current; the present invention performs current correction because when testing the half-wave waveform, the effective value of the half-wave current is not half of the effective value of the full-wave current, and there is a certain multiple deviation. After correction, the current can be made closer to the theoretical value and the error can be reduced.

[0093] Specifically, Figure 6 As shown, the experiment phase begins, the DC even harmonic compensation function is turned on, and the HPU-1510 DC even harmonic spectrum generator is used to provide a half-wave current to determine whether the DC even harmonic compensation is currently started; if so, the current current value I′ is read, and the current is corrected using the current correction multiple;

[0094] I=2×I′×number of correction bits

[0095] After that, the error can be fitted by reading the data from the EEPROM.

[0096] In specific implementation, in the above-mentioned electric energy meter DC even harmonic error compensation method provided in an embodiment of the present invention, step S104 uses the fitted error value to calculate the phase angle offset, which can specifically include: obtaining a functional mapping relationship between the phase angle offset, the phase angle and the error; calculating the phase angle offset according to the fitted error value and the known phase angle, and the obtained functional mapping relationship between the phase angle offset, the phase angle and the error.

[0097] Specifically, when there is no phase angle error:

[0098]

[0099] Among them, P0 represents the power value when there is no phase angle error, U represents the voltage value, and I represents the current value. represents the phase angle;

[0100] When there is a phase angle error:

[0101]

[0102] Where P represents the power value when there is a phase angle error. Indicates the phase angle offset (as the compensation value that needs to be solved currently);

[0103] Error value Error:

[0104]

[0105] Further we can get:

[0106]

[0107] Finally, the expression of the functional mapping relationship between the phase angle offset, phase angle and error is obtained as follows:

[0108]

[0109] It should be understood that in the prior art, the amount of compensation is calculated by using the error and an approximate solution is obtained, and the formula is as follows:

[0110]

[0111] The functional relationship between the phase angle and the error value obtained by the prior art is:

[0112]

[0113] It can be seen that the compensation value calculation formula of the present invention is a congruent relationship, while the compensation value calculation formula of the prior art uses approximate calculation. The calculation accuracy of the present invention is higher than the approximate calculation result. The present invention provides a good theoretical calculation basis for DC even harmonic compensation.

[0114] Further, in the specific implementation, in the above-mentioned electric energy meter DC even harmonic error compensation method provided in the embodiment of the present invention, step S105 performs corresponding compensation for the DC even harmonics according to the calculated phase angle offset, which can specifically include: converting the calculated phase angle offset into a phase correction register value; performing corresponding compensation for the DC even harmonics through the phase correction register value, specifically compensating the phase.

[0115] Specifically, the phase correction register value PHUS:

[0116]

[0117] In addition, in the specific implementation, in the above-mentioned electric energy meter DC even harmonic error compensation method provided in the embodiment of the present invention, step S104 uses the fitted error value to calculate the power compensation value, which can specifically include: obtaining the function mapping relationship between the power compensation value, the phase angle and the error; calculating the power compensation value according to the fitted error value and the known phase angle, and the obtained power compensation value, the function mapping relationship between the phase angle and the error.

[0118] Specifically, when performing compensation calculation, the amount of compensation is the active value, that is, the adjustment is performed by changing the active power:

[0119] P′=P+λQ

[0120] Among them, P′ represents the active value after compensation, P represents the active value before compensation, Q represents the reactive value before compensation, and λ represents the power compensation value (as the compensation value currently to be solved).

[0121] That is, the expression of the compensation value is:

[0122]

[0123] Error value Error:

[0124]

[0125] Obtain the compensation value λ:

[0126]

[0127] The error and phase angle are derived as Substituting into the above formula:

[0128]

[0129] The sin function is replaced by cos, and the final functional relationship between λ and Error is obtained:

[0130]

[0131] That is, the expression of the functional mapping relationship between the power compensation value, phase angle and error is:

[0132]

[0133] Similarly, it can be seen that the compensation value calculation formula of the present invention is a congruent relationship, and the calculation accuracy is higher than the approximate calculation result. The present invention provides a good theoretical calculation basis for DC even harmonic compensation.

[0134] Furthermore, in a specific implementation, in the above-mentioned DC even harmonic error compensation method of the electric energy meter provided in an embodiment of the present invention, step S105 performs corresponding compensation for the DC even harmonics according to the calculated power compensation value, which may specifically include: using the product of the calculated power compensation value and the reactive amount before compensation plus the active amount before compensation, that is, P′=P+λQ, to obtain the compensated active value; and performing corresponding compensation for the DC even harmonics by using the compensated active value, that is, adjusting by changing the active power.

[0135] In specific implementation, in the above-mentioned electric energy meter DC even harmonic error compensation method provided in an embodiment of the present invention, after executing step S103 to fit the error value, it can also include: obtaining an error offset according to different error values ​​obtained by different mutual inductors under the same current; and correcting the fitted error value using the error offset.

[0136] It is understandable that when performing error compensation for electric energy meters of the same type and batch, a fixed set of error data will be used for compensation calculation. Fig.10 As shown, due to some reasons such as the manufacturing process, the errors measured by different electric energy meters are different, and there is a certain deviation from the default data. In order to adjust the error caused by the measurement deviation between different mutual inductors, the present invention adds error offset for fine adjustment.

[0137] After compensation, the experimentally measured deviation value can be reduced to between -0.5% and 0.5%.

[0138] Fig.11 The following is a schematic diagram showing the relationship between the compensation error value and the current value of an electric energy meter. The specific data is shown in the following table:

[0139] Current 5A 10A 15A 20A 25A 30A 35A 40A 45A 50A 55A 60A 65A 72A error -0.4472 -0.3317 -0.3053 -0.2322 -0.0897 -0.0497 0.0703 0.1485 0.2624 0.4315 0.4109 0.4764 0.3688 0.4901

[0140] Then we experimented with six different meters and used a set of mean values ​​to compensate. The experimental data are as follows: Fig.12 The error fluctuations of the six electric energy meters are all around 1%, and there are small deviations between the errors of different meters.

[0141] The error range of the first electricity meter is (-0.5% - 0.5%), with an error of 1.0% above and below.

[0142] The error range of the second electricity meter is (0.9%-1.5%), with an error of 0.6% above and below.

[0143] The error range of the third electricity meter is (-0.6%——-0.3%), with an error of 0.3% up and down.

[0144] The error range of the fourth electricity meter is (0.4%-0.9%), with an error of up and down 0.5%.

[0145] The error range of the 5th electricity meter is (-0.9%——-0.3%), with an error of 0.6% up and down.

[0146] The error range of the 6th electricity meter is (0.5%-1.1%), with an error of 0.6% up and down.

[0147] The present invention utilizes the error offset to correct the fitted error value, which can reduce the deviation of the error value and further improve the compensation effect.

[0148] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0149] Professionals may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in the above description according to function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0150] The steps of the method or algorithm described in conjunction with the embodiments disclosed herein may be implemented directly using hardware, a software module executed by a processor, or a combination of the two. The software module may be placed in a random access memory (RAM), a memory, a read-only memory (ROM), an electrically programmable ROM, an electrically erasable programmable ROM, a register, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.

[0151] In summary, an embodiment of the present invention provides a method for compensating for DC even harmonic errors in an electric energy meter, including: using the least squares method to perform curve fitting on the relationship between error and current to obtain a functional relationship between error and current; reading the current test current value and correcting the current test current value; fitting the error value according to the corrected current value and the obtained functional relationship between error and current; using the fitted error value to calculate the phase angle offset or power compensation value; and according to the calculated phase angle offset or power compensation value, performing corresponding compensation for DC even harmonics. In this way, the functional relationship between error and current is firstly obtained by curve fitting, the error value is fitted in combination with the test current value, and then the phase angle offset or power compensation value is calculated by using the error value for compensation, so that more accurate results can be obtained and the compensation effect can be improved.

[0152] Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0153] The above is a detailed introduction to the DC even harmonic error compensation method for the electric energy meter provided by the present invention. Specific examples are used in this article to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea; at the same time, for general technicians in this field, according to the idea of ​​the present invention, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A method for compensating DC even harmonic errors of electric energy meters, characterized in that: include: The relationship between the error and the current is fitted by the least square method to obtain the functional relationship between the error and the current; Reading the current test current value and correcting the current test current value; Fitting the error value according to the corrected current value and the obtained functional relationship between the error and the current; Calculate the phase angle offset or power compensation value using the fitted error value; According to the calculated phase angle offset or power compensation value, the DC even harmonics are compensated accordingly; The step of calculating the phase angle offset by using the fitted error value includes: Obtaining the functional mapping relationship between phase angle offset, phase angle and error; Calculate the phase angle offset according to the fitted error value and the known phase angle, as well as the acquired functional mapping relationship between the phase angle and the error; The expression of the functional mapping relationship between the phase angle offset, the phase angle and the error is: in, Indicates the phase angle offset; Represents the phase angle; Error represents the error value obtained by fitting.

2. The method for compensating DC even harmonic errors of electric energy meters according to claim 1, characterized in that: The least square method is used to perform curve fitting on the relationship between the error and the current to obtain a functional relationship between the error and the current, including: Test and record the initial error values ​​corresponding to different initial currents without compensation; The least square method is used to fit the relationship between the error and the current, and the functional relationship between the error and the current is fitted; Substituting the recorded initial current and initial error value into the fitted functional relationship, and determining each coefficient in the fitted functional relationship by Gaussian elimination method; Substitute the determined coefficients into the fitted functional relationship to obtain a functional relationship containing only the error and the current.

3. The method for compensating DC even harmonic errors of electric energy meters according to claim 1, characterized in that: The correcting the current test current value includes: Obtain the current correction multiple according to the actual measured value and theoretical value of the current; The current test current value is corrected according to the current correction multiple.

4. The method for compensating DC even harmonic errors of electric energy meters according to claim 1, characterized in that: The method of compensating the DC even harmonics accordingly according to the calculated phase angle offset comprises: Convert the calculated phase angle offset into a phase correction register value; The DC even harmonics are compensated accordingly through the phase correction register value.

5. The method for compensating DC even harmonic errors of electric energy meters according to claim 1, characterized in that: The step of calculating the power compensation value by using the fitted error value includes: Obtaining the functional mapping relationship between power compensation value, phase angle and error; The power compensation value is calculated based on the fitted error value and the known phase angle, and the acquired functional mapping relationship between the power compensation value, the phase angle and the error.

6. The method for compensating DC even harmonic errors of electric energy meters according to claim 5, characterized in that: The expression of the functional mapping relationship between the power compensation value, phase angle and error is: Where, λ represents the power compensation value; Represents the phase angle; Error represents the error value obtained by fitting.

7. The method for compensating DC even harmonic errors of electric energy meters according to claim 6, characterized in that: The method of compensating the DC even harmonics accordingly according to the calculated power compensation value comprises: The product of the calculated power compensation value and the reactive energy before compensation is added to the active energy before compensation to obtain the active energy after compensation. The DC even harmonics are compensated accordingly by means of the compensated active power value.

8. The method for compensating DC even harmonic errors of electric energy meters according to claim 1, characterized in that: After the fitting error value, it also includes: According to different error values ​​obtained by different mutual inductors under the same current, an error offset is obtained; The error value obtained by fitting is corrected using the error offset.

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