Full-range error on-line calibration device and calibration method for low-voltage current transformer

Abstract

The application discloses a full-range error live calibration device and method for a low-voltage current transformer, comprising: a current control unit for outputting full-range calibration current control signals of each frequency; a hetero-frequency calibration current source for outputting full-range hetero-frequency current signals based on the current control signals and injecting the signals into the measured current transformer and a standard current transformer; an open current sensor for measuring a background current signal in real time; a signal decoupling unit for acquiring a mixed-frequency error voltage signal, eliminating a voltage component generated by the background current signal in the mixed-frequency error voltage signal, and acquiring a hetero-frequency error voltage signal; an error measurement unit for calculating ratio error and phase error of the measured current transformer based on the hetero-frequency standard signal and the hetero-frequency error voltage signal; and a data processing unit for determining calibration error under a power frequency frequency mapping based on the ratio error and the phase error under each hetero-frequency frequency.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electric energy metering equipment calibration, and more particularly to a full-range error live calibration device and method for a low-voltage current transformer. BACKGROUND

[0002] A low-voltage current transformer (referred to as a low-voltage CT) is a key device for measuring current, and its metering performance plays an important role in electric energy trade settlement. Nowadays, State Grid Corporation has put forward very high requirements for power supply reliability, and the traditional low-voltage CT verification method relying on power failure is difficult to be applied on a large scale, so it is necessary to develop a kind of transformer error calibration technology which can be carried out live, has high accuracy and is highly related to the traditional quantity transmission system.

[0003] At present, the research on live calibration technology for transformer error mainly focuses on using original load current or modulating background current to achieve full-range coverage, but such methods are easily affected by background current fluctuation and harmonic interference, and it is difficult to guarantee the accuracy and stability of the calibration results.

[0004] The prior art scheme represented by "A low-voltage current transformer on-line calibration system and method" (application number: 202110443641.4) has the design idea of connecting a secondary line in parallel to the primary side of the low-voltage CT to build an auxiliary current channel, and connecting a adjustable phase-shifting power supply to the secondary line. By adjusting the phase and amplitude of the current output by the phase-shifting power supply, the vector superposition with the original load current is realized, and then the synthesized current meeting the specific amplitude requirement is generated, so that the low-voltage CT primary side current reaches full range coverage without affecting the normal load operation, thereby meeting the needs of on-line full range error calibration. To achieve high-precision measurement, the method uses an open-type standard current transformer installed in the additional secondary line path to measure the standard value of the synthesized current, and then compares the standard current with the secondary output current of the measured CT through the transformer calibrator to calculate and analyze the error characteristics of the low-voltage CT at different working current points. This scheme can carry out calibration without power-off and without load, and has certain engineering practicability and representativeness. Although the above prior art realizes on-line calibration of low-voltage current transformers without power-off, it still has many technical limitations and cannot meet the calibration requirements of high precision, full range and dynamic working conditions. First of all, the method is highly sensitive to the actual load current on site. Since the system uses the method of combining load current and phase-shifting current to build calibration current, once the load on site fluctuates, the amplitude and phase of the synthesized current will change, which cannot be kept stable, directly affecting the accuracy of the primary side current, and thus it is difficult to realize controllable coverage of multiple current points and full range calibration. Secondly, due to the influence of harmonic pollution in the power grid, high-order harmonic components are inevitably superimposed in the synthesized current, so that the standard current and the output signal of the measured CT contain high-order harmonic currents, and the traditional differential error calibration method cannot synchronize the current at each frequency point to offset, and the existence of harmonics will seriously interfere with the accuracy of error measurement.

[0005] Therefore, there is a need for a low-voltage current transformer full-range error on-line calibration device and method. SUMMARY

[0006] The present application provides a low-voltage current transformer full-range error on-line calibration device and method to solve the problem of on-line calibration of low-voltage current transformers.

[0007] In order to solve the above problems, according to one aspect of the present application, a low-voltage current transformer full-range error on-line calibration device is provided, which comprises: a current control unit, a hetero-frequency calibration current source, an open current sensor, a standard current transformer, a measured current transformer, a signal decoupling unit, an error measurement unit and a data processing unit, the primary cable of the hetero-frequency calibration current source is connected to the standard current transformer and the measured current transformer in turn, and the open current sensor is connected to the bus background current primary line; wherein,

[0008] The current control unit is connected with the hetero-frequency calibration current source, and is used for outputting a full-range calibration current control signal of each frequency to the hetero-frequency calibration current source.

[0009] The hetero-frequency calibration current source is used for outputting a full-range hetero-frequency current signal to the current transformer to be measured and the standard current transformer based on the current control signal.

[0010] The open current sensor is connected with the signal decoupling unit, and is used for measuring a background current signal in real time and transmitting the background current signal to the signal decoupling unit.

[0011] The signal decoupling unit is connected with the error measurement unit, and is used for obtaining a mixed-frequency error voltage signal, eliminating a voltage component of the background current signal in the mixed-frequency error voltage signal, obtaining a hetero-frequency error voltage signal, and transmitting the hetero-frequency error voltage signal to the error measurement unit.

[0012] The error measurement unit is connected with the hetero-frequency calibration current source and the data processing unit respectively, and is used for calculating a ratio error and a phase error of the current transformer to be measured based on the hetero-frequency standard signal and the hetero-frequency error voltage signal, and transmitting the ratio error and the phase error to the data processing unit.

[0013] The data processing unit is used for determining a calibration error under a power frequency mapping based on the ratio error and the phase error under each hetero-frequency.

[0014] Preferably, the standard current transformer and the current transformer to be measured are connected according to the analog comparison method, the secondary side heteronym ends of the standard current transformer and the current transformer to be measured are connected, a connection point is a, the connection is made through a first shunt and a second shunt, one end of the first shunt is connected at the point a, the other end of the first shunt is grounded, one end of the second shunt is connected at the point b, and the other end of the second shunt is grounded; one end of a standard secondary load of the standard current transformer is connected at the point c, and the other end of the standard secondary load is grounded, a voltage at the end of the first shunt is the mixed-frequency error voltage signal, a voltage at the end of the second shunt is the standard voltage signal, the mixed-frequency error voltage signal is output to the signal decoupling unit after amplification and analog-to-digital conversion, and the standard voltage signal is output to the error measurement unit as the hetero-frequency standard signal after amplification and analog-to-digital conversion.

[0015] Preferably, the mixed-frequency error voltage signal is:

[0016] (1)

[0017] wherein, is the mixed-frequency error voltage signal; R a is a resistance of the first shunt; is a secondary current value of the standard current transformer; is a secondary current value of the measured transformer; is a background current signal.

[0018] Preferably, the signal decoupling unit rejects a voltage component generated by the background current signal in the mixed frequency error voltage signal to obtain a hetero-frequency error voltage signal, and then determines the initial range of parameters and , obtains the mixed frequency error voltage signal as the original acquisition signal x(n), and decomposes x(n) based on the VMD algorithm to obtain initial intrinsic mode functions, including: constructing a signal decoupling effect objective function , establishing a parameter optimization objective, and iteratively obtaining the quadratic penalty term and the Lagrange multiplier term when the function minimum value, and bringing the optimized quadratic penalty term and the Lagrange multiplier term into the VMD algorithm, so that the signal x(n) is decomposed into a series of intrinsic mode functions with different frequencies; wherein,

[0019] The parameter optimization objective is:

[0020] (2)

[0021] (3)

[0022] (4)

[0023] The intrinsic mode functions with different frequencies obtained by decomposition are:

[0024] (5)

[0025] wherein, is the sum of the square deviations of the dominant frequency of each intrinsic mode function and the target frequency; is the reconstruction error; is the cross degree between the intrinsic mode functions; K is the number of intrinsic mode functions; , are the i th and j th frequency intrinsic mode functions respectively; the coefficient ; is the frequency domain error signal under the hetero-frequency;

[0026] Based on the intrinsic mode functions obtained by decomposition, the frequency domain signal is converted into a time domain error signal, including:

[0027] (6)

[0028] wherein, is the frequency The time-domain error signal component.

[0029] Preferably, the error measurement unit calculates the ratio error and phase error of the current transformer under test based on the heterogeneous standard signal and the heterogeneous error voltage signal, including:

[0030] (7)

[0031] in, and respectively for The ratio error and phase error of frequency and current; It is a frequency of The time-domain error signal component; It is a frequency of The heterogeneous standard signal; j represents a complex number.

[0032] Preferably, the data processing unit determines the calibration error under the power frequency mapping based on the ratio error and phase error at each different frequency, including:

[0033] Based on the ratio error and phase error at each different frequency, the WSVR algorithm is used for regression to obtain the trained regression function: and power frequency Substitute the values ​​to obtain the calibration error under the power frequency mapping;

[0034] in, This refers to the calibration error under power frequency mapping. For frequency The corresponding weighting coefficients are as follows. Let y be the standard deviation of the current frequency data, and y be the overall error bias term.

[0035] According to another aspect of the present invention, a calibration method is provided based on the full-range error live calibration device for a low-voltage current transformer as described above, the method comprising:

[0036] The current control unit outputs full-range calibration current control signals of each frequency to the heterogeneous frequency calibration current source.

[0037] Using a different frequency calibration current source, a full-range different frequency current signal is output based on the current control signal and injected into the current transformer under test and the standard current transformer.

[0038] The background current signal is measured in real time using an open-type current sensor and transmitted to the signal decoupling unit.

[0039] The signal decoupling unit obtains the mixed error voltage signal and removes the voltage component generated by the background current signal in the mixed error voltage signal to obtain the error voltage signal at the different frequency and transmit to the error measurement unit;

[0040] The error measurement unit calculates the ratio error and phase error of the current transformer to be measured based on the error voltage signal at the different frequency and the standard signal at the different frequency and transmits to the data processing unit;

[0041] The data processing unit determines the calibration error under the power frequency mapping based on the ratio error and phase error under each different frequency.

[0042] Preferably, the method further comprises:

[0043] The standard current transformer and the current transformer to be measured are connected according to the analog comparison method measurement error connection, the secondary side of the standard current transformer and the current transformer to be measured are connected to the different name terminals, the connection point is a, the connection is made through the first shunt and the second shunt, one end of the first shunt is connected to the a point, the other end of the first shunt is grounded, one end of the second shunt is connected to the b point, the other end of the second shunt is grounded; one end of the standard secondary load of the standard current transformer is connected to the c point, the other end of the standard secondary load is grounded, the voltage at the end of the first shunt is the mixed error voltage signal, the voltage at the end of the second shunt is the standard voltage signal, the mixed error voltage signal is output to the signal decoupling unit after amplification and analog-to-digital conversion, and the standard voltage signal is output to the error measurement unit as the standard signal at the different frequency after amplification and analog-to-digital conversion.

[0044] Preferably, the mixed error voltage signal is:

[0045] (1)

[0046] wherein, is the mixed error voltage signal; R a is the resistance of the first shunt; is the secondary current value of the standard transformer; is the secondary current value of the transformer to be measured; is the background current signal.

[0047] Preferably, the voltage component generated by the background current signal in the mixed error voltage signal is removed to obtain the error voltage signal at the different frequency, comprising:

[0048] The initial range of the parameters and is determined, the mixed error voltage signal is obtained as the original acquisition signal x(n), and the initial intrinsic mode function is obtained by decomposing x(n) based on the variational mode decomposition algorithm VMD, and then the parameters and are determined and The initial range of the initial range, obtain the mixed frequency error voltage signal as the original acquisition signal x(n), and decompose x(n) based on the variational mode decomposition algorithm VMD to obtain the initial intrinsic mode function, including: constructing a signal decoupling effect objective function , establishing a parameter optimization target, and iteratively obtaining the quadratic penalty term and the Lagrange multiplier term when the function minimum value , , , ,

[0049] The parameter optimization target is:

[0050] (2)

[0051] (3)

[0052] (4)

[0053] The intrinsic mode function of different frequencies obtained by decomposition is:

[0054] (5)

[0055] Wherein, is the sum of the deviation squares of the dominant frequency of each intrinsic mode function and the target frequency; is the reconstruction error; is the cross degree between each intrinsic mode function; K is the number of intrinsic mode functions; , The i-th and j-th frequency intrinsic mode functions are respectively; the coefficient ; is the frequency domain error signal under the different frequency frequency; Based on the intrinsic mode function obtained by decomposition, the frequency domain signal is converted into a time domain error signal, including:

[0056]

[0057] (6) Wherein,

[0058] is the time domain error signal component with a frequency of .

[0059] Preferably, wherein the error measuring unit is used to calculate the ratio error and phase error of the current transformer to be measured based on the different frequency standard signal and the different frequency error voltage signal, including:

[0060] (7)​

[0061] wherein, and respectively are the ratio error and phase error of the frequency current; is the time domain error signal component with a frequency of ; is the hetero-frequency standard signal with a frequency of ; j represents a complex number.

[0062] Preferably, wherein the data processing unit is used to determine the calibration error under the power frequency frequency mapping based on the ratio error and phase error under each hetero-frequency frequency, comprising:

[0063] based on the ratio error and phase error under each hetero-frequency frequency, regression is carried out using the WSVR algorithm to obtain a trained regression function: and the power frequency frequency is brought in to obtain the calibration error under the power frequency frequency mapping;

[0064] wherein, is the calibration error under the power frequency frequency mapping; is the corresponding weight coefficient under the frequency , and is the current frequency data standard deviation, and y is the error overall bias term.

[0065] Based on another aspect of the present application, the present application provides a computer readable storage medium having a computer program stored thereon, the program being executed by a processor to implement the steps of any one of the calibration methods of the low-voltage current transformer based full-range error live calibration device.

[0066] Based on another aspect of the present application, the present application provides an electronic device, comprising:

[0067] The computer readable storage medium described above; and

[0068] One or more processors for executing the program in the computer readable storage medium.

[0069] The application provides a full-range error live calibration device and method for a low-voltage current transformer, comprising: a current control unit, configured to output a full-range calibration current control signal of each frequency to a different-frequency calibration current source; the different-frequency calibration current source, configured to output a full-range different-frequency current signal based on the current control signal and inject the signal into the to-be-tested current transformer and a standard current transformer; an open current sensor, configured to measure a background current signal in real time and transmit the signal to the signal decoupling unit; the signal decoupling unit, connected to the error measurement unit, configured to obtain a mixed-frequency error voltage signal, eliminate a voltage component generated by the background current signal in the mixed-frequency error voltage signal, obtain a different-frequency error voltage signal, and transmit the signal to the error measurement unit; the error measurement unit, configured to calculate a ratio error and a phase error of the to-be-tested current transformer based on the different-frequency standard signal and the different-frequency error voltage signal, and transmit the signal to the data processing unit; and the data processing unit, configured to determine a calibration error under a power frequency mapping based on the ratio error and the phase error under each different-frequency frequency. BRIEF DESCRIPTION OF DRAWINGS

[0070] The exemplary embodiments of the application can be more completely understood in reference to the following drawings:

[0071] Figure 1 FIG. 1 is a structural schematic diagram of a full-range error live calibration device for a low-voltage current transformer according to an embodiment of the application;

[0072] Figure 2 FIG. 2 is a connection structural diagram of a full-range error live calibration device for a low-voltage current transformer according to an embodiment of the application;

[0073] Figure 3 FIG. 3 is a structural diagram of a different-frequency calibration current source according to an embodiment of the application;

[0074] Figure 4 FIG. 4 is a flowchart of a calibration method 400 for a full-range error live calibration device for a low-voltage current transformer according to an embodiment of the application. DETAILED DESCRIPTION

[0075] Exemplary embodiments of the invention will now be described with reference to the accompanying drawings. However, the invention may be embodied in many different forms and is not limited to the embodiments described herein. These embodiments are provided to fully and completely disclose the invention and to fully convey its scope to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the drawings is not intended to limit the invention. In the drawings, the same units / elements are referred to by the same reference numerals.

[0076] Unless otherwise stated, the terms used herein (including technical terms) have their common meaning as understood by one of ordinary skill in the art. Furthermore, it is understood that terms defined in commonly used dictionaries should be understood to have a meaning consistent with the context of their relevant field, and not to be interpreted as having an idealized or overly formal meaning.

[0077] This invention proposes a method for live calibration of low-voltage current transformers (CTs). This method includes real-time cancellation of the background current signal on the secondary side of the current transformer under test, injection of a different frequency current (different from the power frequency) into the primary circuit of the low-voltage CT, measurement of the error of the different frequency current using a parameter adaptive high-precision signal decoupling algorithm, and frequency regression calculation of the error data. This method can effectively map the measurement results of the different frequency current to the error of the power frequency measurement current of the same range, thus solving the problem of calibration results being offset due to different current frequencies.

[0078] Figure 1 This is a schematic diagram of the structure of a live-line calibration device 100 for the full-range error of a low-voltage current transformer according to an embodiment of the present invention. Figure 1As shown, the low-voltage current transformer full-range error live calibration device provided by the embodiment of the application adopts an open current sensor to measure the background current in real time, clearly determines the background current component of the secondary side of the to-be-tested transformer, eliminates the influence of the background current on the measurement, and significantly suppresses the influence of the load current fluctuation and harmonics on the calibration accuracy; in the signal processing link, through the frequency-domain signal decoupling technology of the frequency modulation of the full-range calibration current and adaptive parameter optimization, the frequency-different secondary signal containing the error information of the transformer is extracted, and the error data measured under the frequency-different excitation is accurately mapped to the power frequency error in combination with the weighted regression model, so that the error evaluation of the in-service low-voltage current transformer in the full-range range is realized; the application has strong dynamic adaptability, high measurement accuracy, and can provide a feasible solution path for the live calibration of the transformer under complex working conditions. The low-voltage current transformer full-range error live calibration device 100 provided by the embodiment of the application comprises: a current control unit 101, a frequency-different calibration current source 102, an open current sensor 103, a standard current transformer 104, a to-be-tested current transformer 105, a signal decoupling unit 106, an error measurement unit 107, and a data processing unit 108. Wherein, the primary cable of the frequency-different calibration current source is sequentially connected to the standard current transformer and the to-be-tested current transformer, and the open current sensor is connected to the bus background current primary circuit.

[0079] Preferably, the current control unit 101 is connected with the frequency-different calibration current source, and is configured to output a full-range calibration current control signal of each frequency to the frequency-different calibration current source.

[0080] Preferably, the frequency-different calibration current source 102 is configured to output a full-range frequency-different current signal to the to-be-tested current transformer 105 and the standard current transformer 104 based on the current control signal.

[0081] Preferably, the standard current transformer and the to-be-tested current transformer are connected according to the analog comparison method error connection, the frequency-different name terminals of the secondary sides of the standard current transformer and the to-be-tested current transformer are connected, the connection point is a, the first shunt and the second shunt are connected, one end of the first shunt is connected to the point a, the other end of the first shunt is grounded, one end of the second shunt is connected to the point b, and the other end of the second shunt is grounded; one end of the standard secondary load of the standard current transformer is connected to the point c, the other end of the standard secondary load is grounded, the voltage at the end of the first shunt is a mixed frequency error voltage signal, the voltage at the end of the second shunt is a standard voltage signal, the mixed frequency error voltage signal is output to the signal decoupling unit after amplification and analog-to-digital conversion, and the standard voltage signal is output to the error measurement unit as a frequency-different standard signal after amplification and analog-to-digital conversion.

[0082] Preferably, the opening current sensor 103 is connected with the signal decoupling unit for measuring the background current signal in real time and transmitting to the signal decoupling unit.

[0083] In combination Figure 2 As shown in the present application, the low-voltage current transformer full-range energized calibration device comprises a current control unit, an opening current sensor, a standard current transformer, a current transformer to be measured, a different-frequency calibration current source, a signal decoupling unit, an error measurement and data processing unit. Wherein, the primary cable of the different-frequency calibration current source is sequentially threaded into the standard transformer CT0 and the current transformer to be measured CT X The opening current sensor is connected to the bus background current primary circuit; and the two transformers are connected according to the simulation comparison method for measuring error, the two transformer secondary side different name ends are connected to the point a in Figure 2 R a and R b are high-precision shunts, one end of R a is connected to point a, and the other end is grounded, one end of R b is connected to point b, and the other end is grounded. R c is a standard secondary load of the transformer, one end is connected to point c, and the other end is grounded. R a The voltage at the end is a mixed-frequency error voltage signal, R b The voltage at the end is a standard voltage signal, and the mixed-frequency error voltage signal and the standard voltage signal are amplified by PGA and converted into digital signals by ADC.

[0084] The opening current sensor can measure the bus background current value (i.e. the background current signal) in real time and transmit the signal to the signal decoupling unit, so that the signal decoupling unit performs difference operation to remove the voltage component of the bus load current in the mixed-frequency error voltage signal.

[0085] In combination Figure 2 As shown in the present application, the current control unit generates full-range calibration current control signals of each frequency, and the different-frequency calibration current source receives the digital signals output by the current control unit, thereby controlling the frequency and amplitude of the full-range calibration current, and outputting full-range calibration current amplitude 0-500A, frequency 40Hz, 45Hz, 55Hz, 60Hz, 65Hz, 70Hz, 75Hz, 80Hz, 85Hz, 90Hz. The main function of the different-frequency calibration current source is to convert the control signal into a high-power current signal for providing full-range different-frequency calibration current. The principle of the device is as follows Figure 3The switch power supply converts the signal of the current control unit into stable voltage and current required by the power output module. The power output module adopts multi-stage digital power amplifier in parallel, uses multi-stage self-current sharing technology, uses 12V high-power power supply in parallel, has maximum output power of 6000W, and has adjustable output power, and realizes stable output of maximum 500A. The power supply is also equipped with power source state monitoring function, which can monitor the power output current value and equipment temperature, and ensure the safety of equipment use.

[0086] In the present application, the open current sensor measures the background current signal ΔI P1 , the shunt Ra flows through the secondary differential current of two mutual inductors (i.e. ΔI0-ΔI1), and the voltage across the shunt Ra and the background current signal are synchronously collected and based on the formula , the mixed frequency error voltage signal U mix is obtained. Through this operation, the background current signal on the secondary side of the measured mutual inductor is offset in real time, which can effectively eliminate the problem of reduced signal-to-noise ratio caused by the background current signal and improve the measurement accuracy. Because the accuracy of the open current sensor and the CT X is different, the background current voltage cannot be completely eliminated, and at this time U mix is the frequency aliasing signal of the residual background current signal and the mixed frequency error signal.

[0087] Preferably, the signal decoupling unit 106 is connected with the error measurement unit, used to obtain the mixed frequency error voltage signal, eliminate the voltage component generated by the background current signal in the mixed frequency error voltage signal, obtain the mixed frequency error voltage signal, and transmit to the error measurement unit.

[0088] Preferably, the mixed frequency error voltage signal is:

[0089] (1)

[0090] wherein, is the mixed frequency error voltage signal; R a is the resistance of the first shunt; is the secondary current value of the standard mutual inductor; is the secondary current value of the measured mutual inductor; is the background current signal.

[0091] Preferably, the signal decoupling unit 106 eliminates the voltage component generated by the background current signal in the mixed frequency error voltage signal to obtain the mixed frequency error voltage signal, and includes:

[0092] determine the initial range of the parameters and, obtain the mixed frequency error voltage signal as the original collection signal x(n), and based on the VMD algorithm, the initial intrinsic mode function is obtained by decomposing x(n), and then the parameters and The initial range of the initial range, the mixed frequency error voltage signal is obtained as the original acquisition signal x(n), and the initial intrinsic mode function is obtained based on the VMD algorithm, including: constructing a signal decoupling effect target function , establishing a parameter optimization target, and iteratively obtaining the quadratic penalty term and the Lagrange multiplier term , and the optimized quadratic penalty term and the Lagrange multiplier term are brought into the VMD algorithm, so that the signal x(n) is decomposed into a series of intrinsic mode functions with different frequencies; wherein,

[0093] The parameter optimization target is:

[0094] (2)

[0095] (3)

[0096] (4)

[0097] The intrinsic mode functions with different frequencies obtained by decomposition are:

[0098] (5)

[0099] Wherein, is the sum of the square deviations of the dominant frequency of each intrinsic mode function and the target frequency; is the reconstruction error; is the cross degree between the intrinsic mode functions; K is the number of intrinsic mode functions; 、 The i-th and j-th frequency intrinsic mode functions are respectively; the coefficient ; is the frequency domain error signal under the different frequency frequency;

[0100] The frequency domain signal is converted into a time domain error signal based on the intrinsic mode function obtained by decomposition, including:

[0101] (6)

[0102] Wherein, is the time domain error signal component with a frequency of .

[0103] In the present application, the signal decoupling unit separates the different frequency error signal and the residual background current signal to obtain the different frequency error voltage signal Δ U D ​The method is based on adaptive variational mode decomposition technology, and the key parameters affecting the accuracy of variational mode decomposition algorithm are adaptively selected by a Bayesian optimization algorithm, including the optimal values of a quadratic penalty factor alpha and a Lagrange multiplier tau. The optimization strategy effectively ensures that the VMD algorithm can accurately decompose the mixed frequency signal into a series of band-limited intrinsic mode functions, while eliminating the modes containing white noise, thereby significantly improving the signal-to-noise ratio of the mixed frequency signal.

[0104] In the application, the VMD algorithm changes the traditional intrinsic mode constraint variational problem into an unconstrained variational problem by simultaneously introducing a quadratic penalty term alpha and a Lagrange multiplier term tau. The quadratic penalty term alpha is used to ensure the reconstruction accuracy in the presence of Gaussian noise, and its setting should be inversely proportional to the noise level of the signal; the Lagrange multiplier term is used to maintain the strictness of the constraint. The Bayesian optimization algorithm is used to adaptively estimate the quadratic penalty term and the Lagrange multiplier term, thereby improving the decoupling effect of the frequency domain signal.

[0105] In the application, first, the initial range is defined as x(n) is the original collected signal, and VMD decomposition is performed on x(n) to obtain the initial intrinsic mode function. A signal decoupling effect objective function is constructed as The parameter optimization objective is as shown in formula (2), and the parameters when the function minimum value is iteratively obtained 、 :

[0106] (2)

[0107] (3)

[0108] (4)

[0109] Wherein, is the sum of the square deviations of the dominant frequency of each intrinsic mode function and the target frequency; is the reconstruction error, and the specific calculation method is as shown in formula (3); is the degree of intersection between the intrinsic mode functions (BLIMF), and the correlation coefficient between the intrinsic mode functions is used here, as shown in formula (4), wherein K is the number of intrinsic mode functions, is the first i frequency intrinsic mode function, and the coefficient j .

[0110] The optimized quadratic penalty term and the Lagrange multiplier term are brought into the VMD algorithm, and the signal is decomposed into a series of intrinsic mode functions (5) with different frequencies:

[0111] ​ (5)

[0112] obtained frequency error signal at the different frequency and then convert the frequency domain signal into a time domain error signal as shown in equation (6):

[0113] (6)

[0114] Preferably, the error measurement unit 107 is connected to the different frequency calibration current source and the data processing unit respectively, for calculating the ratio error and phase error of the current transformer to be tested based on the different frequency standard signal and the different frequency error voltage signal, and transmitting to the data processing unit.

[0115] Preferably, the error measurement unit 107 calculates the ratio error and phase error of the current transformer to be tested based on the different frequency standard signal and the different frequency error voltage signal, including:

[0116] (7)

[0117] wherein, and respectively are the ratio error and phase error of the frequency current; is the time domain error signal component with a frequency of ; is the different frequency standard signal with a frequency of ; and j represents a complex number.

[0118] In the present application, the error measurement unit calculates the ratio error and phase error of the frequency current, and obtains:

[0119] (7)

[0120] wherein, and respectively are the ratio error and phase error of the frequency current; is the time domain error signal component with a frequency of ; is the different frequency standard signal with a frequency of ; and j represents a complex number.

[0121] Preferably, the data processing unit 108 is used to determine the calibration error under the power frequency frequency mapping based on the ratio error and phase error under each different frequency.

[0122] Preferably, the data processing unit 108 determines the calibration error under the power frequency mapping based on the ratio error and phase error under each different frequency, comprising:

[0123] Based on the ratio error and phase error under each different frequency, regression is carried out by using WSVR algorithm to obtain the trained regression function: , and the power frequency is brought in to obtain the calibration error under the power frequency mapping;

[0124] , wherein, is the calibration error under the power frequency mapping; is the corresponding weight coefficient under the frequency , and is the current frequency data standard deviation, and y is the error overall bias term.

[0125] In the application, the data processing unit collects error data under each different frequency, carries out frequency-error regression calculation by using the weighted support vector regression (WSVR) algorithm, and obtains the calibration error value under the power frequency mapping.

[0126] The low-voltage CT primary side excitation current is the root cause of error generation, the excitation impedance is a direct parameter affecting the error, and the error characteristics of the low-voltage CT have a significant correlation with the current frequency. The error values under different frequencies have certain internal relations. The application calculates the error values under each range point of the power frequency current by using the regression algorithm from the error of the different frequency current.

[0127] The WSVR algorithm is used to regress the different frequency errors, and different weights are given according to the closeness of each different frequency point to the power frequency, so as to reduce the influence of the frequency difference on the regression result. The Lagrange function for training the regression model of the algorithm is formula (8), and the input quantity of the WSVR algorithm is the current frequency , wherein i =1…n) is the current frequency of each measurement point, and the error value , is the error under the frequency . C is a penalty factor, which is set according to the data complexity; and and y are obtained by training, wherein is the normal vector of the data regression hyperplane, and y is the hyperplane displacement term; and the output quantity is the error value under the frequency of 50 Hz.

[0128] (8)

[0129] In the calculation process, the and Gaussian radial kernel function (9) under frequency error, the nonlinear error data is mapped to high-dimensional space, and the linear separable line of the data is improved, wherein is the standard deviation of error data.

[0130] (9)

[0131] The obtained trained regression function is formula (10), and the error after the regression of the power frequency frequency is:

[0132] (10)

[0133] wherein, is the calibration error under the mapping of the power frequency frequency; is the frequency corresponding weight coefficient under the frequency is the standard deviation of current frequency data, and y is the overall bias term of error.

[0134] The on-frequency current energized calibration device of the application can effectively obtain the low-voltage CT error under energized working condition, and the technology can effectively avoid the 50Hz frequency interference of the main power grid, improve the separation degree and observability of the error signal. By canceling the influence of the background current on the measurement at the secondary side, the application can extract the error signal of the mutual inductor under the premise of uninterrupted power supply and without affecting the normal operation of the power grid, thereby significantly improving the practicability and safety of energized calibration.

[0135] In the application, the on-site test of the full-range error energized calibration device of the low-voltage current transformer is carried out, and the evaluation of the measurement uncertainty is carried out. The mathematical model of the device measurement error is shown in Table 1.

[0136] Table 1 Uncertainty mathematical model of calibration value

[0137] <![CDATA[ d x = d p + Δd 1 +Δd 2 +Δd 3 +Δd 4 +Δd 5+ Δd 6 ]]> <![CDATA[ δ x = δ p + Δδ 1+ Δδ 2+ Δδ 3+ Δδ 4+ Δδ 5+ Δδ 6 ]]> <![CDATA[ d x ratio difference for the current transformer under test <![CDATA[ δ x for the phase difference of the current transformer under test <![CDATA[ d p ratio difference of the current transformers being calibrated as measured on the device <![CDATA[ δ p to measure the phase difference of the current transformer being calibrated on the device Δd 1 is the ratio of the standardizer ​ Δδ 1 is the standardizer phase inaccuracy ​ Δd 2 is the influence of the inaccuracy of the measuring device ​ Δδ 2 is the influence of the inaccuracy of the measuring device ​ Δd 3 is the influence of the working electromagnetic field ​ Δδ 3 is the influence of the working electromagnetic field ​ Δd 4 is the influence of external electromagnetic field interference ​ Δδ 4 is the influence of external electromagnetic field interference ​ Δd 5 is the influence of the secondary load ​ Δδ 5 is the influence of the secondary load ​ Δd 6 for the background current residual ​ Δδ 6 for the background current residual ​

[0138] In the application, the energized calibration test under the on-site working condition is carried out, and the full-range current error data of the to-be-tested low-voltage CT is obtained. Then the to-be-tested mutual inductor is removed, and the mutual inductor calibration equipment of the national high-voltage measurement station is used to compare the error measurement results of two times, and two mutual inductors are measured. The #1 mutual inductor has an accuracy level of 0.2S level, a variable ratio of 300 / 5, and a background current of 25A, and the #2 mutual inductor has an accuracy level of 0.2S level, a variable ratio of 300 / 5, and a background current of 20A. The comparison results are shown in Table 2, and the error difference of the two test results is less than 0.05S level mutual inductor error specified value. The device can effectively and accurately obtain the full-range power frequency current error of the low-voltage current transformer under the on-site working condition.

[0139] Table 2 Comparison results of calibration error

[0140]

[0141] The device of the present application can accurately obtain the measurement error of the running low-voltage CT under the condition of no power failure, significantly improves the reliability and accuracy of the live calibration, and does not need to power off or bypass the measured system, significantly improves the power supply reliability, and simplifies the on-site operation process. By using the excitation of the different frequency current and the offset of the load secondary current, the disturbance of the load current to the error measurement of the transformer can be minimized, and the measurement error suppression ability and the measurement precision can be effectively improved by combining the frequency domain signal decoupling and the error regression algorithm processing technology.

[0142] Figure 4 The flowchart of the calibration method 400 of the full-range error live calibration device based on the low-voltage current transformer according to the embodiment of the present application. As shown in Figure 4 The calibration method 400 of the full-range error live calibration device based on the low-voltage current transformer according to the embodiment of the present application starts from step 401, in which the current control unit outputs the full-range calibration current control signal of each frequency to the different frequency calibration current source.

[0143] In step 402, the different frequency calibration current source outputs the full-range different frequency current signal based on the current control signal to the measured current transformer and the standard current transformer.

[0144] In step 403, the open current sensor measures the background current signal in real time and transmits it to the signal decoupling unit.

[0145] In step 404, the signal decoupling unit obtains the mixed frequency error voltage signal, removes the voltage component generated by the background current signal in the mixed frequency error voltage signal, obtains the different frequency error voltage signal, and transmits it to the error measurement unit.

[0146] Preferably, the method further comprises:

[0147] The standard current transformer and the measured current transformer are connected according to the simulation comparison method, the different name ends of the secondary sides of the standard current transformer and the measured current transformer are connected, the connection point is a, the connection is made through the first shunt and the second shunt, one end of the first shunt is connected to the a point, the other end of the first shunt is grounded, one end of the second shunt is connected to the b point, and the other end of the second shunt is grounded; one end of the standard secondary load of the standard current transformer is connected to the c point, the other end of the standard secondary load is grounded, the voltage at the end of the first shunt is the mixed frequency error voltage signal, the voltage at the end of the second shunt is the standard voltage signal, the mixed frequency error voltage signal is output to the signal decoupling unit after amplification and analog-to-digital conversion, and the standard voltage signal is output to the error measurement unit as the different frequency standard signal after amplification and analog-to-digital conversion.

[0148] Preferably, the mixed frequency error voltage signal is:

[0149] (1)

[0150] wherein, is a mixed frequency error voltage signal; R a is a resistance of the first shunt; is a standard transformer secondary current value; is a to-be-measured transformer secondary current value; is a background current signal.

[0151] Preferably, wherein the voltage component generated by the background current signal in the mixed frequency error voltage signal is removed to obtain a heterodyne error voltage signal, comprising:

[0152] determining the initial range of parameters and, obtaining the mixed frequency error voltage signal as the original acquisition signal x(n), and decomposing the initial intrinsic mode function based on the VMD algorithm, and then determining the initial range of parameters and obtaining the mixed frequency error voltage signal as the original acquisition signal x(n), and decomposing the initial intrinsic mode function based on the VMD algorithm, comprising: constructing a signal decoupling effect objective function , establishing a parameter optimization target, and iteratively obtaining the quadratic penalty term and the Lagrange multiplier term when the function minimum value, and bringing the optimized quadratic penalty term and the Lagrange multiplier term into the VMD algorithm, so that the signal x(n) is decomposed into a series of intrinsic mode functions of different frequencies; wherein,

[0153] The parameter optimization target is:

[0154] (2)

[0155] (3)

[0156] (4)

[0157] The intrinsic mode functions of different frequencies decomposed are:

[0158] (5)

[0159] wherein, is the sum of the square deviations of the dominant frequency of each intrinsic mode function and the target frequency; is a reconstruction error; is the cross degree between each eigenmode function; K is the number of eigenmode functions; 、 is the i th and j th frequency eigenmode function respectively; coefficient ; is the cross degree between each eigenmode function; K is the number of eigenmode functions; is the frequency domain error signal under the different frequency;

[0160] The frequency domain signal is converted into a time domain error signal based on the eigenmode functions obtained by decomposition, including:

[0161] (6)

[0162] wherein, is the time domain error signal component with the frequency of .

[0163] In step 405, the ratio error and phase error of the current transformer to be measured are calculated based on the different frequency standard signal and the different frequency error voltage signal by using the error measurement unit, and are transmitted to the data processing unit.

[0164] Preferably, wherein the ratio error and phase error of the current transformer to be measured are calculated based on the different frequency standard signal and the different frequency error voltage signal by using the error measurement unit, including:

[0165] (7)

[0166] wherein, and respectively is the ratio error and phase error of the frequency current; is the time domain error signal component with the frequency of . is the different frequency standard signal with the frequency of ; j represents a complex number. In step 406, the calibration error under the power frequency frequency mapping is determined based on the ratio error and phase error under each different frequency by using the data processing unit.

[0167] Preferably, wherein the calibration error under the power frequency frequency mapping is determined based on the ratio error and phase error under each different frequency by using the data processing unit, including:

[0168] Based on the ratio error and phase error under each different frequency, the WSVR algorithm is used for regression to obtain the trained regression function:

[0169] , and the power frequency frequency is brought in to obtain the calibration error under the power frequency frequency mapping; wherein,

[0170] ​for the power frequency mapping calibration error; for the frequency for the corresponding weight coefficient, for the current frequency data standard deviation, y is an error overall bias term.

[0171] The calibration method 400 of the low-voltage current transformer based full-range error live calibration device of the embodiments of the present application corresponds to the low-voltage current transformer based full-range error live calibration device 100 of another embodiment of the present application, which will not be described here. The calibration method of the low-voltage current transformer based full-range error live calibration device of the embodiments of the present application is not limited to the above-mentioned step sequence.

[0172] Based on another aspect of the present application, the present application provides a computer readable storage medium having stored thereon a computer program which, when executed by a processor, implements the steps of any one of the calibration methods of the low-voltage current transformer based full-range error live calibration device.

[0173] Based on another aspect of the present application, the present application provides an electronic device comprising:

[0174] the above-mentioned computer readable storage medium; and

[0175] one or more processors for executing the program in the computer readable storage medium.

[0176] The present application has been described by reference to a few embodiments. However, as understood by those skilled in the art, other embodiments, etc. within the scope of the present application are equivalent to the above disclosed embodiments.

[0177] Generally, all terms used in the present application are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a" or "an" means "at least one" unless otherwise clearly indicated by the context of the disclosure. The steps of any methods disclosed herein need not be performed in the exact order disclosed, unless explicitly stated.

[0178] Those skilled in the art will appreciate that embodiments of the present application can be supplied as a method, a system, or a computer program product. Accordingly, the present application can take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present application can take the form of a computer program product on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROMs, optical storage media, etc.) embodying computer readable program code thereon.

[0179] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. Figure 1 one or more flow or blocks. Figure 1 one or more flow or blocks.

[0180] These computer program instructions can also be stored in a computer readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer readable memory produce an article of manufacture including instructions which implement the function specified in the flowchart block or blocks. Figure 1 one or more flow or blocks. Figure 1 one or more flow or blocks.

[0181] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. Figure 1 one or more flow or blocks. Figure 1 one or more flow or blocks.

[0182] Finally, it should be noted that the above-mentioned embodiments are merely used to illustrate the technical solutions of the present application, but not limit the technical solutions of the present application. Although the present application has been described in detail with reference to the above-mentioned embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or equivalent replaced without departing from the spirit and scope of the present application, and any modification or equivalent replacement should be covered in the protection scope of the present application.

Claims

1. A full range error band live calibration device for low voltage current transformers, characterized in that, The device comprises a current control unit, a hetero-frequency calibration current source, an open current sensor, a standard current transformer, a to-be-measured current transformer, a signal decoupling unit, an error measurement unit and a data processing unit, the primary cable of the hetero-frequency calibration current source is sequentially connected to the standard current transformer and the to-be-measured current transformer, and the open current sensor is connected to the primary line of the bus background current; wherein, The current control unit is connected with the hetero-frequency calibration current source and is used for outputting a full-range calibration current control signal of each frequency to the hetero-frequency calibration current source; The hetero-frequency calibration current source is used for outputting a full-range hetero-frequency current signal to the to-be-measured current transformer and the standard current transformer based on the current control signal; The open current sensor is connected with the signal decoupling unit and is used for measuring a background current signal in real time and transmitting the background current signal to the signal decoupling unit; The signal decoupling unit is connected with the error measurement unit and is used for obtaining a mixed-frequency error voltage signal, removing a voltage component generated by the background current signal in the mixed-frequency error voltage signal to obtain a hetero-frequency error voltage signal, and transmitting the hetero-frequency error voltage signal to the error measurement unit; The error measurement unit is connected with the hetero-frequency calibration current source and the data processing unit respectively, is used for calculating a ratio error and a phase error of the to-be-measured current transformer based on a hetero-frequency standard signal and the hetero-frequency error voltage signal, and transmitting the ratio error and the phase error to the data processing unit; The data processing unit is used for determining a calibration error under a power frequency frequency mapping based on the ratio error and the phase error under each hetero-frequency frequency.

2. The apparatus of claim 1, wherein, The standard current transformer and the to-be-measured current transformer are connected according to an analog comparison method error connection, the non-identical name ends of the secondary sides of the standard current transformer and the to-be-measured current transformer are connected, a connection point is a, the connection is made through a first shunt and a second shunt, one end of the first shunt is connected to the point a, the other end of the first shunt is grounded, one end of the second shunt is connected to the point b, and the other end of the second shunt is grounded; one end of a standard secondary load of the standard current transformer is connected to the point c, the other end of the standard secondary load is grounded, a voltage at the end of the first shunt is a mixed-frequency error voltage signal, a voltage at the end of the second shunt is a standard voltage signal, the mixed-frequency error voltage signal is amplified and analog-converted and then output to the signal decoupling unit, and the standard voltage signal is amplified and analog-converted and then output to the error measurement unit as a hetero-frequency standard signal.

3. The apparatus of claim 2, wherein, The mixed-frequency error voltage signal is: （1） wherein, is a mixed error voltage signal; R a is a resistance of the first shunt; is a standard transformer secondary current value; is a to-be-measured transformer secondary current value; is a background current signal.

4. The apparatus of claim 1, wherein, The signal decoupling unit removes the voltage component generated by the background current signal in the mixed-frequency error voltage signal to obtain a hetero-frequency error voltage signal, and includes: Determination parameter and The initial range is obtained by acquiring the mixing error voltage signal as the original acquisition signal x(n), and the initial intrinsic mode function is obtained by decomposing x(n) based on the variational mode decomposition algorithm VMD, and then a signal decoupling effect target function is constructed, a parameter optimization target is established, and the quadratic penalty term and the Lagrange multiplier term when the function minimum value is iteratively obtained are obtained, and the optimized quadratic penalty term and the Lagrange multiplier term are brought into the VMD algorithm, so that the signal x(n) is decomposed into a series of intrinsic mode functions with different frequencies; wherein, The parameter optimization target is: （2） （3） （4） The intrinsic mode functions of different frequencies obtained by decomposition are: （5） wherein, is the sum of square deviation of dominant frequency of each eigenmode function from the target frequency; is the reconstruction error; is the cross degree between each eigenmode function; K is the number of eigenmode functions; , are the i-th and j-th frequency eigenmode functions, respectively; the coefficient ; is the error signal in frequency domain at the different frequency. The frequency domain signal is converted into a time domain error signal based on the intrinsic mode functions obtained by decomposition, and includes: （6） wherein is a time-domain error signal component at a frequency of 2 kHz.

5. The apparatus of claim 1, wherein, The error measurement unit calculates a ratio error and a phase error of the to-be-measured current transformer based on the hetero-frequency standard signal and the hetero-frequency error voltage signal, and includes: （7） in, and These are the frequency-current ratio error and the phase error, respectively. It is a frequency of The time-domain error signal component; It is a frequency of The heterogeneous standard signal; j represents a complex number.

6. The apparatus of claim 1, wherein, The data processing unit determines a calibration error under a power frequency frequency mapping based on the ratio error and the phase error under each hetero-frequency frequency, and includes: Based on the ratio error and phase error under each frequency, the WSVR algorithm is used for regression to obtain the trained regression function: And the power frequency Is brought in to obtain the calibration error under the power frequency mapping. wherein, is the calibration error for the power frequency mapping; is the frequency corresponding weight coefficient, is the current frequency data standard deviation, y is the error overall bias term.

7. A calibration method of a full-range error band energized calibration device based on the low voltage current transformer according to any one of claims 1-6, characterized in that, The method comprises: The current control unit outputs each frequency full-range calibration current control signal to the different frequency calibration current source; The different frequency calibration current source outputs full-range different frequency current signal based on the current control signal to the current transformer to be tested and the standard current transformer; The open current sensor measures the background current signal in real time and transmits it to the signal decoupling unit; The signal decoupling unit obtains the mixed error voltage signal and eliminates the voltage component generated by the background current signal in the mixed error voltage signal to obtain the different frequency error voltage signal and transmits it to the error measurement unit; The error measurement unit calculates the ratio error and phase error of the current transformer to be tested based on the different frequency standard signal and the different frequency error voltage signal and transmits them to the data processing unit; The data processing unit determines the calibration error under the power frequency frequency mapping based on the ratio error and phase error under each different frequency.

8. The method of claim 7, wherein, The method further comprises: The standard current transformer and the current transformer to be tested are connected according to the analog comparison method measurement error connection, the non-name ends of the secondary sides of the standard current transformer and the current transformer to be tested are connected, the connection point is a, the connection is made through the first shunt and the second shunt, one end of the first shunt is connected to point a, the other end of the first shunt is grounded, one end of the second shunt is connected to point b, and the other end of the second shunt is grounded; one end of the standard secondary load of the standard current transformer is connected to point c, and the other end of the standard secondary load is grounded, the voltage at the end of the first shunt is the mixed error voltage signal, the voltage at the end of the second shunt is the standard voltage signal, the mixed error voltage signal is output to the signal decoupling unit after amplification and analog-to-digital conversion, and the standard voltage signal is output to the error measurement unit after amplification and analog-to-digital conversion. Different frequency error voltage signal.

9. The method of claim 8, wherein, The mixed error voltage signal is: （1） wherein, is a mixed error voltage signal; R a is a resistance of the first shunt; is a standard transformer secondary current value; is a to-be-measured transformer secondary current value; is a background current signal.

10. The method of claim 7, wherein, Eliminating the voltage component generated by the background current signal in the mixed error voltage signal to obtain the different frequency error voltage signal comprises: Determination parameter and The initial range is obtained by acquiring the mixing error voltage signal as the original acquisition signal x(n), and the initial intrinsic mode function is obtained by decomposing x(n) based on the variational mode decomposition algorithm VMD, and then a signal decoupling effect target function is constructed, a parameter optimization target is established, and the quadratic penalty term when the function minimum value is iteratively obtained and the Lagrange multiplier term , and the optimized quadratic penalty term and the Lagrange multiplier term are brought into the VMD algorithm, so that the signal x(n) is decomposed into a series of intrinsic mode functions with different frequencies; wherein, The parameter optimization target is: （2） （3） （4） The intrinsic mode function of different frequencies obtained by decomposition is: （5） wherein, is the sum of square deviation of dominant frequency of each eigenmode function from the target frequency; is the reconstruction error; is the cross degree between each eigenmode function; K is the number of eigenmode functions; , are the i-th and j-th frequency eigenmode functions, respectively; the coefficient ; is the error signal in frequency domain at the different frequency; Converting the frequency domain signal into a time domain error signal based on the intrinsic mode function obtained by decomposition comprises: （6） wherein is a time-domain error signal component at a frequency of 2 kHz.

11. The method of claim 7, wherein, The error measurement unit calculates the ratio error and phase error of the current transformer to be tested based on the different frequency standard signal and the different frequency error voltage signal, which comprises: （7） wherein and are the ratio error and phase error of the frequency current, respectively; is the time domain error signal component with a frequency of is the heterodyne standard signal with a frequency of j represents a complex number.​ 12. The method of claim 7, wherein, The data processing unit determines the calibration error under the power frequency frequency mapping based on the ratio error and phase error under each different frequency, which comprises: Based on the ratio error and phase error under each frequency, the WSVR algorithm is used for regression to obtain the trained regression function: And the power frequency Is brought in to obtain the calibration error under the power frequency mapping. wherein, is the calibration error for the power frequency mapping; is the frequency corresponding weight coefficient, is the current frequency data standard deviation, y is the error overall bias term.

13. A computer readable storage medium having stored thereon a computer program, characterized in that, The program is executed by the processor to realize the steps of the method in any one of claims 7-12.

14. An electronic device, comprising: Comprise: The computer readable storage medium in claim 13; And One or more processors for executing the program in the computer readable storage medium.

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