A Method for Remote Calibration of Electric Energy of AC Charging Piles

Abstract

The present invention discloses a method for remotely calibrating the electric energy of an AC charging pile, which relates to the technical field of electric energy metering and calibration. The method includes: constructing a calibration system; using an error self-diagnosis module to calculate the error and the electrical parameters of the collected signals, obtaining the electrical parameter data and the monitoring error in the calibration signal processing flow, and using a reference signal calibration module to judge the error source and determine the fault repair scheme during calibration; the collected signals include the load signal and the reference signal of the reference signal source; the reference signal source includes a DC reference signal source and an AC reference signal source; based on the fault repair scheme, remotely calibrate the electric energy of the AC charging pile using a laboratory. The present invention can accurately monitor the electrical parameters and the error in the calibration signal processing flow, and improve the accuracy and stability of the signal processing flow.

Description

Technical Field

[0001] The present invention relates to the technical field of electric energy metering and calibration, and particularly to a method for remotely calibrating the electric energy of an AC charging pile. Background Art

[0002] In the field of electric energy metering, traditional calibration methods mainly rely on on-site calibration or laboratory calibration, that is, transporting the device to be calibrated to a place with high-precision standard equipment for comparison and correction. Although this method can ensure the accuracy of calibration, it has many limitations and deficiencies. First of all, on-site calibration or laboratory calibration requires a lot of time and resources. Especially during the transportation process, additional errors may be introduced, and for large or equipment installed in remote areas, the transportation cost is high and the risk is great.

[0003] With the development of technology and the progress of remote communication technology, remote calibration technology has gradually become a research hotspot. However, the current application of remote calibration technology in the field of electric energy metering still faces many challenges. On the one hand, electric energy metering involves multiple electrical parameters (such as voltage, current, power factor, etc.), and the remote transmission and comparison of these parameters are relatively complex, requiring high-precision measurement technology and a stable communication link. On the other hand, the remote calibration process may be affected by environmental factors (such as electromagnetic interference, temperature changes, etc.), resulting in unstable calibration results.

[0004] Some research institutions and enterprises have begun to explore the remote calibration technology of electric energy metering. For example, some research has proposed a remote calibration system based on the Internet of Things and cloud computing. By establishing a calibration database and a server on the network platform, remote monitoring and calibration of metering devices can be realized. However, these systems still need to be further improved and optimized in actual applications, especially in terms of calibration accuracy, real-time performance, and security.

[0005] In addition, although some developed countries are relatively leading in the research and application of remote calibration technology for electric energy metering. For example, the US NIST (National Institute of Standards and Technology) and some metrology institutions in Europe have developed a remote calibration system based on satellite common view technology, using GPS or GNSS satellite signals as a high-precision time reference to achieve remote comparison and calibration of physical quantities such as voltage and frequency. These methods have significant advantages in improving calibration accuracy and reducing costs, but various factors need to be comprehensively considered in the specific implementation and application process. Summary of the Invention

[0006] The purpose of the present invention is to provide a method for remotely calibrating the electric energy of an AC charging pile, which can accurately monitor the errors in the electrical parameter and calibration signal processing flow, and improve the accuracy and stability of the signal processing flow.

[0007] To achieve the above object, the present invention provides the following solutions:

[0008] A method for remote calibration of the electric energy of an AC charging pile, comprising:

[0009] Constructing a calibration system; the calibration system includes a field end and a laboratory; the field end includes an error self-diagnosis module and a reference signal calibration module connected in sequence; the reference signal calibration module is also wirelessly connected to the laboratory;

[0010] Using the error self-diagnosis module to calculate the error and electrical parameters of the collected signals, obtaining electrical parameter data and monitoring errors in the calibration signal processing flow, and using the reference signal calibration module to judge the error source and determine the fault repair plan during calibration; the collected signals include load signals and reference signals of the reference signal source; the reference signal source includes a DC reference signal source and an AC reference signal source;

[0011] Based on the fault repair plan, using the laboratory to remotely calibrate the electric energy of the AC charging pile.

[0012] Optionally, the operation process of the error self-diagnosis module is: using a sampling circuit to collect the load signal and the reference signal of the reference signal source, performing signal superposition according to Thevenin's theorem and Norton's theorem IV, then using an analog-to-digital conversion module to separate the signals, calculating the electrical parameters by the first branch, and calculating the online error by the second branch.

[0013] Optionally, the sampling circuit is composed of a voltage divider and a current divider.

[0014] Optionally, the expression for the error calculation is:

[0015]

[0016] where C 监测误差 is the monitoring error of the self-diagnosis function, %; U 基准电压额定值 is the initial parameter after meter calibration; U 基准电压还原值 is the real-time parameter of the error self-diagnosis.

[0017] Optionally, the operation process of the reference signal calibration module is: after biasing the AC reference voltage of the reference signal source, alternately passing it through a voltage-to-frequency conversion module with the DC reference voltage, converting it into corresponding frequency signals, and determining the time interval signal and pulse signal corresponding to the frequency signals by a frequency counter, and finally transmitting the time interval signal and the pulse signal to the laboratory for calibration through wireless communication; wherein, the voltage-to-frequency conversion module includes a main path voltage-to-frequency conversion module and a standby voltage-to-frequency conversion module, and the on-off of the main path voltage-to-frequency conversion module and the standby voltage-to-frequency conversion module is controlled by a program-controlled switch.

[0018] Optionally, during the alternating conversion by the voltage-frequency conversion module, fault judgment is performed based on data performance, and the fault repair solution during calibration is determined to be enabling a standby voltage-frequency converter or recommending replacing the electricity meter.

[0019] Optionally, the process of the fault judgment is as follows:

[0020] When the main path voltage-frequency conversion module is adopted by the voltage-frequency conversion module, the DC reference signal before conversion is set as U1, the AC reference signal is set as U2, the DC frequency signal after conversion is set as f1, the AC frequency signal is set as f2, and the voltage-frequency conversion of the main path is set as k1;

[0021] If the data of f1 is normal and the data of f2 has an error, it is judged that the AC reference signal U2 has an error;

[0022] If the data of f1 has an error and the data of f2 is normal, it is judged that the DC reference signal U1 has an error;

[0023] If the data of both f1 and f2 have errors, but it is judged that the voltage-frequency conversion k1 has an error;

[0024] If the data of both f1 and f2 have errors, and it is that k1, U1 or k1, U2 or U1, U2 or k1, U1, U2 have errors, and the error occurrence location cannot be determined. At this time, the voltage-frequency conversion module is replaced with a standby voltage-frequency converter, and the DC frequency signal after conversion is set as f3, the AC frequency signal is set as f4, and the standby voltage-frequency conversion is set as k2;

[0025] If the data of f3 is normal and the data of f4 has an error, it is judged that the voltage-frequency conversion k1 and the AC reference signal U2 have errors;

[0026] If the data of f4 is normal and the data of f3 has an error, it is judged that the voltage-frequency conversion k1 and the DC reference signal U1 have errors;

[0027] If the data of both f3 and f4 have errors, but it is judged that the DC reference signal U1 and the AC reference signal U2 have errors;

[0028] If the data of both f3 and f4 have errors, and it is judged that the voltage-frequency conversion k1, the DC reference signal U1, and the AC reference signal U2 all have errors. If k2 is also not credible, it may also be that k2, U1, U2 all have errors, or k1, k2, U1, U2 all have errors. At this time, it is recommended to replace the electricity meter.

[0029] Optionally, the operation process in the laboratory is as follows: Use the time interval counter and pulse counter in the frequency counter to traceability with the standard source at the laboratory end, calculate the voltage difference, and substitute it into the voltage deviation formula for calculation.

[0030] Optionally, the voltage deviation formula is:

[0031]

[0032] Wherein, △t l and △t r are respectively the differences in adjacent time intervals at the laboratory end and the on-site end, f l and f r are respectively the frequency values after voltage frequency conversion at the laboratory end and the on-site end, f p is the frequency of the satellite synchronous clock source, K l is the conversion coefficient of the voltage frequency converter at the laboratory end, N l and N r are respectively the number of pulses per unit time at the laboratory end and the on-site end.

[0033] According to the specific embodiments provided by the present invention, the following technical effects are disclosed by the present invention:

[0034] The present invention discloses a method for remotely calibrating the electric energy of an AC charging pile. The method includes constructing a calibration system; using an error self-diagnosis module to calculate the error and electrical parameters of the collected signals, obtaining the electrical parameter data and the monitoring error in the calibration signal processing flow, and using a reference signal calibration module to judge the error source and determine the fault repair plan during calibration; the collected signals include load signals and reference signals of the reference signal source; the reference signal source includes a DC reference signal source and an AC reference signal source; based on the fault repair plan, the laboratory is used to remotely calibrate the electric energy of the AC charging pile. The present invention can accurately monitor the electrical parameters and the error in the calibration signal processing flow, and improve the accuracy and stability of the signal processing flow. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0036] Figure 1 is a schematic flow chart of the method for remotely calibrating the electric energy of the AC charging pile of the present invention;

[0037] Figure 2 is a schematic structural diagram of the system in this embodiment;

[0038] Figure 3 This is the signal superposition schematic diagram in this embodiment;

[0039] Figure 4 This is the signal schematic diagram using the main path voltage - frequency conversion module in this embodiment;

[0040] Figure 5 This is the signal schematic diagram using the standby voltage - frequency conversion module in this embodiment;

[0041] Figure 6 This is the schematic diagram of the remote calibration device in this embodiment;

[0042] Figure 7 This is the remote calibration logic schematic diagram in this embodiment. Detailed implementation manners

[0043] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0044] The purpose of the present invention is to provide a method for remotely calibrating the electric energy of an AC charging pile, which can accurately monitor electrical parameters and calibrate the errors in the signal processing flow, improving the accuracy and stability of the signal processing flow.

[0045] To make the above - mentioned objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation manners.

[0046] As Figure 1 shown, the present invention provides a method for remotely calibrating the electric energy of an AC charging pile, including:

[0047] Step 100: Construct a calibration system; the calibration system includes a field end and a laboratory; the field end includes an error self - diagnosis module and a reference signal calibration module connected in sequence; the reference signal calibration module is also wirelessly connected to the laboratory.

[0048] Step 200: Use the error self - diagnosis module to calculate the error and electrical parameters of the collected signal, obtaining the electrical parameter data and the monitoring error in the calibration signal processing flow, and use the reference signal calibration module to judge the error source and determine the fault repair plan during calibration; the collected signals include load signals and reference signals of the reference signal source; the reference signal source includes a DC reference signal source and an AC reference signal source.

[0049] Step 300: Based on the fault repair solution, remotely calibrate the electric energy of the AC charging pile using a laboratory.

[0050] The following embodiments are provided based on the above technical solutions.

[0051] As the system structure in step 100, as Figure 2 shown, the on-site end includes an error self-diagnosis module and a reference signal calibration module. The error self-diagnosis module of the system includes a sampling circuit, an analog-to-digital conversion module, a signal separation link, an online error calculation module, an electrical parameter calculation module, and a reference signal calibration module.

[0052] The system working process is as follows: The load signal and the reference signal of the reference signal source are simultaneously sampled through the sampling circuit, and according to Thevenin's theorem and Norton's theorem four, they are superimposed on the load signal of voltage or current. This is similar to serially connecting a high-precision voltage signal source to the voltage input terminal of the watt-hour meter; and parallely connecting a high-precision current signal source to the current input terminal. The signal superposition of the load signal and the reference signal is as Figure 3 shown.

[0053] After the superposition is completed, it is converted into a digital signal by the analog-to-digital conversion module. These digital signals are then transmitted to the signal separation link, where the load signal and the reference signal are separated. The reference signal is sent to the online error calculation module for error analysis. Using the factory calibration parameters and real-time parameters, the monitoring error calculation formula is used to calculate the monitoring error. This formula calculates the self-diagnosis function monitoring error C 基准电压额定值 by comparing the difference between U 基准电压还原值 and U 监测误差 The calculation formula is:

[0054]

[0055] where C 监测误差 is the self-diagnosis function monitoring error, %; U 基准电压额定值 is the initial parameter after meter calibration; U 基准电压还原值 is the real-time parameter of error self-diagnosis.

[0056] The monitoring error calculated by this formula can intuitively reflect the performance change of the watt-hour meter during the metering process, aiming to observe the stability of the signal in the entire processing flow. At the same time, the separated load signal is sent to the electrical parameter calculation module for necessary electrical parameter calculation. During this process, the meter calibration parameters provide necessary parameter support for the electrical parameter calculation module and the online error calculation module.

[0057] During the monitoring process, the error self-diagnosis module generates a large number of error monitoring reports. These reports are stored in the electricity meter through data storage technology for subsequent query and analysis. In addition, the host computer can remotely obtain the above reports through the remote acquisition function for further analysis and processing.

[0058] The function of the reference signal calibration module is to ensure the high precision of the reference signal source in the error self-diagnosis system. Therefore, the present invention proposes a remote calibration method based on satellite common view technology. The reference signal calibration module is connected to the reference signal source of the error self-diagnosis module, and uses a program-controlled switch to control the on-off relationship between the DC reference signal, AC reference signal and main and standby voltage-frequency converters, realizing the precise calibration of the reference signal. During the calibration process, the system judges the error source according to the data performance of different signal sources. For example, when only the DC reference signal has an error, it can be determined that there is a problem with the DC signal source itself; when both the DC and AC reference signals have errors but meet specific conditions, it may be that there is a fault in the voltage-frequency conversion link. Through this logical judgment method, the system can quickly locate and isolate the fault point, thus ensuring the accuracy and efficiency of the calibration process. In the face of complex multiple fault situations, the reference signal calibration module will judge whether it is necessary to enable the standby voltage-frequency converter for further diagnosis according to the specific data performance, or directly recommend replacing the electricity meter to solve the problem. The following is the specific process.

[0059] The method includes the following steps:

[0060] 1. Signal conversion:

[0061] Connect the reference signal output by the reference signal source of the error self-diagnosis module to the reference signal calibration module, and use a program-controlled switch to control the on-off of the DC reference signal, AC reference signal and main and standby voltage-frequency converters.

[0062] The voltage-frequency converter (VFC) biases the AC reference voltage output by the reference signal source and alternately converts it into a frequency signal proportional to it through the voltage-frequency conversion module together with the DC reference voltage. The voltage-to-frequency module uses an LM331 chip, which can generate different frequencies according to the input voltage. It can convert a 0-10V voltage into a 0-10KHz frequency pulse signal, with a maximum non-linear distortion less than 0.01%. It still has good performance when the working frequency is as low as 0.1Hz. It has high conversion accuracy, a digital resolution of up to 12 bits, and a simple external circuit. Only a few external components need to be connected to easily form a V / F or F / V conversion circuit. Since the biased AC reference voltage and DC reference voltage themselves cannot be directly used for remote comparison. Through the VFC, the voltage value is indirectly represented as the frequency of the pulse signal. The following is the specific introduction:

[0063] Such as Figure 4As shown, if the f1 data is normal and the f2 data has an error, then the error occurs in the AC reference signal U2, and if the f1 data has an error and the f2 data is normal, then the error occurs in the DC reference signal U1, and if both the f1 and f2 data have errors, but then the error occurs in the voltage-to-frequency conversion k1, and if both the f1 and f2 data have errors, and then the error occurs in k1, U1 or k1, U2 or U1, U2 or k1, U1, U2, and it is impossible to determine the location of the error. At this time, connect the DC reference signal, the AC reference signal to the spare voltage-to-frequency converter.

[0064] As Figure 5 shown, if the f3 data is normal and the f4 data has an error, then the error occurs in the voltage-to-frequency conversion k1 and the AC reference signal U2, and if the f4 data is normal and the f3 data has an error, then the error occurs in the voltage-to-frequency conversion k1 and the DC reference signal U1, and if both the f3 and f4 data have errors, but then the error occurs in the DC reference signal U1 and the AC reference signal U2, and if both the f3 and f4 data have errors, and then the voltage-to-frequency conversion k1, the DC reference signal U1, and the AC reference signal U2 all have errors. If k2 is also not reliable, it may also be that k2, U1, U2 all have errors, or k1, k2, U1, U2 all have errors. At this time, it is recommended to replace the meter.

[0065] C 基准电压校准误差 is the deviation degree between the value after calibration of the reference voltage and the actual value of the reference voltage, %; the calibration error calculation formula is:

[0066]

[0067] In the formula, U 基准电压实际值 is the real-time measured value of the reference error; U 基准电压校准值 is the value after calibration of the reference error.

[0068] In order to make the reference signal source in the error self-diagnosis module absolutely accurate, it is necessary to perform DC voltage traceability. And synchronizing the clock information on the GPS satellite as the carrier and medium for non-physical standard transmission can achieve DC voltage parameter traceability. After the bias voltage of the error self-diagnosis module passes through the voltage-to-frequency converter, the frequency converted by the voltage-to-frequency converter is traced through the satellite second pulse, and the time interval counter and the pulse counter are used to trace with the standard source at the laboratory end, calculate the voltage difference, and substitute it into the voltage deviation formula for calculation, so as to ensure the accuracy of the reference signal source. The voltage deviation formula is as follows:

[0069]

[0070] Among them, △t l and △t r are respectively the differences between adjacent time intervals at the laboratory end and the on-site end, f l and f r are respectively the frequency values after voltage-frequency conversion at the laboratory end and the on-site end, f p is the frequency of the satellite synchronous clock source (usually 1 Hz), K l is the conversion coefficient of the voltage-frequency converter at the laboratory end, N l and N r are respectively the number of pulses at the laboratory end and the on-site end within a unit time (such as within a second pulse period).

[0071] As Figures 6 - 7 shown, the AC power remote calibration system in this embodiment is deployed in an electric vehicle charging station containing multiple AC charging piles. The charging station is located in a relatively remote area where it is not easy to conduct frequent on-site calibrations. Therefore, adopting the method of the present invention can significantly improve the calibration efficiency and reduce the labor and logistics costs.

[0072] Error self-diagnosis module: Integrate a sampling circuit, an analog-to-digital conversion module, and a signal separation link inside the AC charging pile. The voltage and current signals of each charging pile are collected through the sampling circuit and converted into digital signals through the analog-to-digital conversion module. The signal separation link is used to separate the load signal from the reference signal to ensure the accuracy of error self-diagnosis.

[0073] Reference signal calibration module: Set a reference signal source at the center of the charging station. The reference signal source is synchronized with an external high-precision time reference through satellite common view technology. The reference signal source outputs high-precision AC voltage and current signals as the reference standard for calibrating the charging piles in the entire charging station.

[0074] Remote calibration server: Set up a remote calibration server near the charging station or in a remote data center, which is responsible for receiving the calibration data uploaded by each charging pile and processing and analyzing the data through a preset calibration algorithm. The server is also responsible for storing calibration records and reports for subsequent auditing and traceability.

[0075] Start the calibration process: The system administrator sends a calibration start instruction to each charging pile through the remote control system. After receiving the instruction, the charging pile starts the error self-diagnosis module and the reference signal calibration module.

[0076] Error self-diagnosis: The error self-diagnosis module inside the charging pile starts to work, collects voltage and current signals in real time, and processes them through the analog-to-digital conversion module and the signal separation link. The online error calculation module uses a preset monitoring error calculation formula to calculate and monitor the error situation of the signal during the processing flow in real time.

[0077] Reference signal calibration: The charging pile accesses the AC voltage and current signals of the reference signal source to the error self-diagnosis module through a program-controlled switch as the calibration reference. The reference signal calibration module accurately calibrates the metering circuit inside the charging pile according to the difference between the reference signal and the load signal. During the calibration process, the system records and transmits relevant calibration data to the remote calibration server.

[0078] Data analysis and report: After receiving the calibration data uploaded by each charging pile, the remote calibration server processes and analyzes the data using a remote calibration algorithm based on satellite common view technology. The server generates a detailed calibration report, including key information such as the error comparison before and after calibration, calibration time, calibration results, etc.

[0079] Expected effect: Through the application of this embodiment, the accuracy of electric energy metering of the AC charging pile has been significantly improved. The remote calibration method not only reduces the labor and logistics costs of on-site calibration, but also avoids additional errors that may be introduced during transportation. At the same time, the integrated application of the error self-diagnosis module and the reference signal calibration module ensures the stability and reliability of the charging pile during long-term use.

[0080] Therefore, as can be seen from the above, by integrating the error self-diagnosis module and the reference signal calibration module, the present invention realizes the real-time monitoring and high-precision calibration of errors in the electric energy metering process. This design reduces the error accumulation caused by environmental factors and equipment aging. By adopting a remote calibration method based on satellite common view technology, it ensures the high precision and stability of the calibration process, thereby improving the accuracy of electric energy metering. Compared with traditional electric energy calibration methods, the present invention does not require transporting the device to be calibrated to a laboratory or calibration center, greatly saving time and transportation costs and reducing risks. Especially for large-scale or remote-area devices, the advantages of remote calibration are more significant, shortening the calibration cycle, accelerating the speed of equipment put into use, reducing manual intervention through an automated and intelligent calibration process, and improving calibration efficiency. At the same time, the real-time monitoring function of the error self-diagnosis module ensures that the device can also be calibrated at any time during operation, guaranteeing the real-time accuracy of the metering results.

[0081] In addition, the error self-diagnosis module and the reference signal calibration module of the present invention can ensure the long-term stability and consistency of the metering results. The proposal and implementation of the present invention promote the application of remote calibration technology in the field of electric energy metering.

[0082] When using the device for the remote calibration scheme of alternating current energy, several key aspects need to be particularly noted to ensure the accuracy and reliability of calibration. First of all, the accuracy and stability of the reference signal are the core of the calibration process. Since the reference signal serves as the reference point for calibration, any slight deviation in it may cause significant errors to the entire calibration system. Therefore, the reference signal source must be calibrated regularly and its stability continuously monitored to ensure the precision of remote calibration.

[0083] Secondly, the installation location and method of the device have a direct impact on the calibration results. When installing the error self-diagnosis module and the reference signal calibration module, it is necessary to avoid the influence of environmental factors during the installation process. Especially for the installation of the reference signal module, factors such as electromagnetic interference and environmental temperature changes need to be fully considered to ensure the purity and stability of the signal. Therefore, during the use process, it is necessary to monitor the temperature and humidity of the calibration environment in real time and maintain the stability of the environment to reduce the interference to the calibration results.

[0084] The real-time monitoring and maintenance of the system are also the keys to ensuring the accuracy of calibration data. During the calibration process, it is necessary to regularly check the working status of the error self-diagnosis module to ensure that it can detect and correct errors in a timely manner. At the same time, for the reference signal calibration module, regular calibration and maintenance are also required to ensure its long-term stability and accuracy, thus ensuring the accuracy of power metering.

[0085] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The same or similar parts among the various embodiments can be referred to each other.

[0086] Specific examples are used in this article to elaborate on the principles and implementation methods of the present invention. The descriptions of the above embodiments are only used to help understand the core idea of the present invention; at the same time, for those of ordinary skill in the art, based on the idea of the present invention, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A method for remotely calibrating the electrical energy of an AC charging pile, characterized in that Including: Constructing a calibration system; the calibration system includes a field end and a laboratory; the field end includes an error self-diagnosis module and a reference signal calibration module connected in sequence; The reference signal calibration module is also wirelessly connected to the laboratory; Using the error self-diagnosis module to calculate the error and electrical parameters of the collected signal, obtaining electrical parameter data and the monitoring error in the calibration signal processing flow, and using the reference signal calibration module to judge the error source and determine the fault repair plan during calibration; The collected signals include a load signal and a reference signal of a reference signal source; The reference signal source includes a DC reference signal source and an AC reference signal source; The operation process of the reference signal calibration module is: after offsetting the AC reference voltage of the reference signal source and alternating it with the DC reference voltage, passing it through a voltage-frequency conversion module to convert it into corresponding frequency signals, and using a frequency counter to determine the time interval signal and pulse signal corresponding to the frequency signal, and finally transmitting the time interval signal and the pulse signal to the laboratory for calibration through wireless communication; wherein, the voltage-frequency conversion module includes a main path voltage-frequency conversion module and a standby voltage-frequency conversion module, and the on-off of the main path voltage-frequency conversion module and the standby voltage-frequency conversion module is controlled by a program-controlled switch; during the alternating conversion process through the voltage-frequency conversion module, a fault judgment is made according to the data performance, and the fault repair plan during calibration is determined to enable the standby voltage-frequency converter or recommend replacing the meter; Based on the fault repair plan, using the laboratory to remotely calibrate the electric energy of the AC charging pile.

2. The method for remotely calibrating the electrical energy of an AC charging pile according to claim 1, wherein The operation process of the error self-diagnosis module is: using a sampling circuit to collect the load signal and the reference signal of the reference signal source, performing signal superposition according to Thevenin's theorem and Norton's theorem four, then using an analog-to-digital conversion module to separate the signals, calculating the electrical parameters by the first branch, and calculating the online error by the second branch.

3. The method for remotely calibrating the electric energy of an AC charging pile according to claim 2, wherein, The sampling circuit is composed of a voltage divider and a current divider.

4. The method for remotely calibrating the electric energy of an AC charging pile according to claim 1, characterized in that, The expression of the error calculation is: Among them, C 监测误差 is the self-diagnosis function monitoring error, %; U 基准电压额定值 is the initial parameter after meter calibration; U 基准电压还原值 is the real-time parameter of error self-diagnosis.

5. The method for remotely calibrating the electric energy of an AC charging pile according to claim 1, wherein The process of the fault judgment is: When the main path voltage-frequency conversion module is used in the voltage-frequency conversion module, set the DC reference signal before conversion as U1, the AC reference signal as U2, set the DC frequency signal after conversion as f1, the AC frequency signal as f2, and set the voltage-frequency conversion of the main path as k1; If the f1 data is normal and the f2 data has an error, it is judged that the AC reference signal U2 has an error; If the f1 data has an error and the f2 data is normal, it is judged that the DC reference signal U1 has an error; If there are errors in both f1 and f2 data, but it is determined that there is an error in the voltage-frequency conversion k1; If errors occur in both f1 and f2 data, and then errors occur in k1, U1 or k1, U2 or U1, U2 or k1, U1, U2, and the error location cannot be determined. At this time, replace the voltage-frequency conversion module with a spare voltage-frequency converter, set the converted DC frequency signal as f3, the AC frequency signal as f4, and set the spare voltage-frequency conversion as k2; If the f3 data is normal and the f4 data has an error, it is judged that the voltage-frequency conversion k1 and the AC reference signal U2 have an error; If the f4 data is normal and the f3 data has an error, it is judged that the voltage-frequency conversion k1 and the DC reference signal U1 have an error; If errors occur in both f3 and f4 data, but it is determined that errors occur in the DC reference signal U1 and the AC reference signal U2; If errors occur in both f3 and f4 data, and it is determined that errors occur in the voltage-frequency conversion k1, the DC reference signal U1, and the AC reference signal U2. If k2 is also not credible, it may also be that errors occur in k2, U1, and U2, or errors occur in k1, k2, U1, and U2. In this case, it is recommended to replace the meter.

6. The method for remotely calibrating the electric energy of an AC charging pile according to claim 1, wherein, The operation process in the laboratory is: using the time interval counter and pulse counter in the frequency counter to traceability with the standard source at the laboratory end, finding the voltage difference, and substituting it into the voltage deviation formula for calculation.

7. The method for remotely calibrating the electric energy of an AC charging pile according to claim 6, wherein The voltage deviation formula is: where, △t l and △t r are the differences between adjacent time intervals at the laboratory end and the field end respectively, f l and f r are the frequency values after voltage frequency conversion at the laboratory end and the field end respectively, f p is the frequency of the satellite synchronous clock source, K l is the conversion coefficient of the voltage frequency converter at the laboratory end, N l and N r are the number of pulses per unit time at the laboratory end and the field end respectively.

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