Clock and monitoring system applied to electric energy meter calibrating device

Abstract

The invention discloses a clock and monitoring system applied to an electric energy meter calibrating device. The clock and monitoring system comprises a standard time-frequency signal generation module used for acquiring a time-frequency signal, and a time-frequency encoding module used for encoding the time-frequency signal and transmitting the time-frequency signal to a time-frequency decoding module; the time-frequency decoding module is used for decoding the coding result to obtain a time-frequency signal; the NTP time service module is used for providing time service for the electric energy meter calibrating device according to the timestamp; the frequency generation module is used for providing reference frequency for the electric energy meter calibrating device according to the frequency signal; the time difference and state monitoring module is used for monitoring each module according to the second pulse signal to obtain operation state information and time difference information of each module; the monitoring platform is used for displaying and storing the time difference information and the operation state signal; according to the invention, the precision of time frequency reference and the real-time monitoring of the equipment state in the verification process can be ensured, and the efficiency and effectiveness of power verification are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of time and frequency synchronization, and in particular relates to a clock and a monitoring system used in an electric energy meter calibration device. Background Art

[0002] Clock testers generally use oven controlled crystal oscillators (OCXOs) or oven controlled crystal oscillators trained by GPS as frequency references. Crystal oscillators have problems such as aging and being greatly affected by temperature. They cannot be traced back in real time during the calibration of electric energy meters, and the working status of the clock tester is not monitored. It is even more unknown whether the clock error of the clock calibrator is out of tolerance. Once an out-of-tolerance is found, it can only be known afterwards, which seriously affects power production. To reverse the current unfavorable factors, there is an urgent need for a device that can monitor the accuracy and working status of the timing terminal in real time and can replace the existing clock tester. The development of a standard clock that can be traced back to the superior time and frequency reference and transmitted to the electric energy meter calibration device, and a device that can monitor the timing terminal, is particularly critical for improving timing accuracy and work efficiency. Summary of the invention

[0003] In order to solve the above technical problems, the present invention proposes a clock and monitoring system used in an electric energy meter calibration device to solve the above problems existing in the prior art.

[0004] To achieve the above object, the present invention provides a clock and monitoring system used in an electric energy meter calibration device, comprising:

[0005] Standard time-frequency signal generation module, time-frequency encoding module, time-frequency decoding module, NTP timing module, frequency generation module, time difference and status monitoring module and monitoring platform;

[0006] Among them, the standard time-frequency signal generating module, the time-frequency encoding module, and the time-frequency decoding module are connected in sequence, and the time-frequency decoding module is respectively connected to the NTP timing module, the frequency generating module, and the time difference and status monitoring module; the time difference and status monitoring module is connected to the monitoring platform;

[0007] The standard time-frequency signal generating module is used to obtain a time-frequency signal, wherein the time-frequency signal includes a frequency signal, a second pulse signal and a timestamp;

[0008] The time-frequency encoding module is used to encode the time-frequency signal and transmit it to the time-frequency decoding module;

[0009] The time-frequency decoding module is used to decode the encoding result to obtain a time-frequency signal;

[0010] The NTP timing module is used to provide timing services to the electric energy meter verification device according to the timestamp;

[0011] The frequency generation module is used to generate a standard frequency signal according to the pulse-per-second signal to provide a reference frequency for the electric energy meter verification device;

[0012] The time difference and status monitoring module is used to monitor the time-frequency decoding module, the NTP timing module, and the frequency generation module according to the second pulse signal to obtain the operating status information and time difference information of each module;

[0013] The monitoring platform is used to display and store the time difference information and the operation status signal, and transmit them to the production management system of the electric energy meter calibration device.

[0014] Optionally, in the standard time-frequency signal generating module, the time-frequency signal is acquired by tracing back to a reference time-frequency standard through a satellite common-view method.

[0015] Optionally, the time-frequency encoding module and the time-frequency decoding module are connected via an optical fiber.

[0016] Optionally, the time-frequency signal is encoded in the time-frequency encoding module using a digital time encoding method.

[0017] Optionally, the time difference information includes a time deviation signal, a frequency deviation signal, a time delay signal and a time offset signal.

[0018] Optionally, in the time difference and status monitoring module, monitoring the frequency generation module includes measuring the second pulse signal, wherein the process of measuring the second pulse signal includes: taking the second pulse signal as the opening door, measuring the second pulse signal to be measured of the crystal oscillator in the frequency generation module as the coarse clock count at the closing moment, obtaining the count within a clock cycle, amplifying the hysteresis of the second pulse signal to be measured by a linear delay circuit, and then performing a fine clock count, and obtaining the time deviation signal of the second pulse signal according to the coarse clock count and the fine clock count.

[0019] Optionally, in the time difference and status monitoring module, monitoring the frequency generation module also includes measuring the frequency signal, wherein the process of measuring the frequency signal includes: performing a linear slope calculation on the time deviation signal at a fixed time of the electric energy meter calibration device by a time difference method to obtain a frequency deviation signal.

[0020] Optionally, in the time difference and status detection module, monitoring the NTP timing module includes monitoring network synchronization, wherein the process of monitoring network synchronization includes: using the NTP timing module as the master clock and the electric energy meter calibration device as the slave clock, performing time delay and time offset calculations on the master clock and the slave clock through the network timing principle to obtain a time delay signal and a time offset signal.

[0021] Compared with the prior art, the present invention has the following advantages and technical effects:

[0022] The present invention realizes the application of remote traceability technology of time and frequency signals through satellite common view in the power system, that is, the transmission and application from the State Grid Metering Center to the provincial time and frequency standards, and then to the electric energy meter calibration device, realizing the unification of the traceability link. It can be used to transform the automatic calibration station of the electric energy meter, replace the original standard clock tester, and solve the problems of low accuracy and non-traceability in traditional measurement and calibration. The present invention not only ensures the uniformity of the value of the time and frequency reference of the electric energy meter calibration device in the power system and improves the accuracy of electric energy metering, but also achieves real-time monitoring of the accuracy of the time and frequency reference and the status of the equipment during the calibration process, which is more conducive to fair trade and energy saving and consumption reduction in settlement, and improves the efficiency and effectiveness of power calibration.

[0023] Through pilot application, the present invention provides real-time traceable time and frequency signals for the electric energy meter calibration device, which not only improves the accuracy of time and frequency traceability and the accuracy of electric energy measurement, but also monitors the accuracy and status of the time and frequency timing equipment, and knows the real-time status of the equipment, truly unifies timing and monitoring, and makes electric power measurement more fair and scientific. The present invention can be extended to the calibration of other devices with electric energy metering functions, such as energy controllers, charging piles, etc., and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0025] Figure 1 A structural block diagram of a clock and monitoring system used in an electric energy meter calibration device according to an embodiment of the present invention;

[0026] Figure 2 A schematic diagram of a network delay and time offset measurement process according to an embodiment of the present invention;

[0027] Figure 3 A schematic diagram of an application scenario of an embodiment of the present invention;

[0028] Figure 4 It is a structural diagram of the time-frequency value optical fiber transmission system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0029] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0030] It should be noted that the steps shown in the flowcharts of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and that, although a logical order is shown in the flowcharts, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0031] The clock tester in the prior art generally has an oven controlled crystal oscillator (OCXO), or an oven controlled crystal oscillator trained by GPS, which has the following disadvantages:

[0032] 1. It can only provide time, but cannot monitor the clock tester. The working status and timing accuracy of the clock tester cannot be mastered in real time. Even if a problem is found, it is only discovered afterwards, which seriously affects production;

[0033] 2. Real-time traceability is not possible. The independent constant temperature crystal oscillator in the clock test is traced through periodic calibration, but it cannot be traced in real time during production testing. The constant temperature crystal oscillator tamed by GPS is synchronized with the navigation system time, and cannot be directly traced to the timekeeping laboratory of the power system, and does not have real-time traceability.

[0034] 3. Poor accuracy. The accuracy of constant temperature crystal oscillator is generally within 10 -7 ~10 -8 The accuracy of the constant temperature crystal oscillator trained by GPS is generally within 10 -10 ~10 -12 It is one-way timing, has no comparability, and cannot provide early warning when large errors occur.

[0035] The electric energy meter calibration device is an important calibration tool to determine whether the electric energy meter is qualified or not. At present, the electric energy meter calibration device is equipped with a high-precision clock tester. The accuracy and stability of the frequency signal of the clock tester are crucial for the measurement of the built-in clock signal of the electric energy meter. At present, the clock testers of the assembly line electric energy meter calibration devices in various regions need to be calibrated regularly in accordance with the "JJG 180-2002 Calibration Procedure for Quartz Crystal Oscillators in Electronic Measuring Instruments". The clock tester generally uses a constant temperature crystal oscillator (OCXO) or a constant temperature crystal oscillator tamed by GPS as the frequency reference. The crystal oscillator has problems such as aging and being greatly affected by temperature. The status and accuracy of the clock tester are unknown between two calibration cycles, which poses a great hidden danger to the calibration of the electric energy meter. An innovative method is needed to solve the above problems.

[0036] The present invention is a clock and monitoring system used in an electric energy meter calibration device. The clock of the present invention is a traceable time frequency source. The monitoring system of the present invention has the following advantages:

[0037] (1) The device of the present invention transmits the time-frequency signal of common-view traceability to the electric energy meter calibration line by optical fiber transmission. The optical fiber has a small delay, which ensures accuracy and also avoids the disadvantage of communication interruption caused by network security in Ethernet. It ensures stable and reliable signal transmission;

[0038] (2) The clock error and status information of each time-frequency timing terminal of the present invention is uploaded to the monitoring system in real time through the time-frequency coding device. This completely solves the drawback of the original clock tester that can only transmit in one direction without monitoring. It not only achieves high-precision time-frequency transmission, but also can know the clock error and status of the time-frequency timing terminal in real time. The time-frequency coding device also has the function of NTP timing, which can perform NTP timing on the assembly line control computer, and at the same time send the time difference of each assembly line control computer to the production management system, so that the closed-loop management of the timing and monitoring of the assembly line control computer is achieved at the same time.

[0039] The technology of the present invention can be widely used in electric energy meter calibration devices, fundamentally solving the problem that the original clock tester can only provide time to the electric energy meter calibration device but does not monitor the clock tester. By monitoring the time and frequency timing terminal, the accuracy and status of the time and frequency timing terminal can be mastered in real time. It fundamentally avoids the problem that the clock accuracy exceeds the tolerance in the electric energy meter calibration but cannot be known in time, which seriously affects the efficiency of the calibration. This technology meets the terminal application requirements in the power system, from the State Grid Metering Center to the provincial time reference, and then to the electric energy meter calibration, and can be widely promoted on the future smart electric energy meter calibration assembly line. In the future, this technology has great potential for achievement transformation and can also be expanded to other aspects: (1) Calibration and testing of devices with timing functions such as energy controllers, GPS synchronized clocks, and smart charging piles; (2) Providing network timing services for the acquisition master station and billing system to achieve time and frequency synchronization and homology;

[0040] First, the technical terms involved in the following embodiments are explained below:

[0041] GNSS

[0042] The Global Navigation Satellite System is a general term for satellite navigation systems that can provide navigation services worldwide. Currently, the commonly used satellite navigation systems include China's Beidou, the United States' GPS, Russia's GLONASS and the European Union's Galileo.

[0043] Satellite Common-View time transfer

[0044] Using GNSS satellite signals as a common resource, users in two locations measure the time difference between their local clocks and the same satellite clock at the same time, and then calculate the clock deviations of the two locations by comparing the observation results of the two locations. This is referred to as the common view method.

[0045] NTP

[0046] Network Time Protocol (NTP), a protocol defined by RFC (Request For Comments)-1305 standard, is used for time synchronization between a group of distributed time servers and clients. SNTP is a simplified protocol of NTP.

[0047] The following is a description of the technical solutions related to the present invention:

[0048] like Figure 1 As shown, the present invention provides a clock and monitoring system used in an electric energy meter calibration device, which is mainly composed of the following parts: a standard time-frequency signal generating module, a time-frequency encoding module, a time-frequency decoding module, an NTP timing module, a frequency generating module, a time difference and status monitoring module, and a monitoring platform.

[0049] Specifically, the standard time and frequency signal generation module remotely traces the local clock signal to a reference time and frequency standard or benchmark through the GNSS satellite common view method, and provides 1PPS, 10MHz and timestamp signals for the time and frequency encoding module.

[0050] Specifically, the time-frequency encoding module encodes the time information of the received frequency signal (10MHz), pulse-per-second signal (1PPS) and timestamp (date, time) of the standard time-frequency source through time-frequency coding technology, and then converts the encoded information into an optical signal and transmits it to the time-frequency decoding module through optical fiber.

[0051] Specifically, the time-frequency decoding module decodes the time-frequency signal sent by the received time-frequency encoding module. The timestamp generated after decoding is provided to the NTP timing module.

[0052] Specifically, the NTP timing module acts as an NTP timing server to provide NTP and SNTP protocol timing for the electric energy meter calibration computer, wherein the NTP timing module receives timestamp information and performs timing for the electric energy meter calibration computer according to the standard frequency signal and timestamp information.

[0053] Specifically, the frequency generation module transmits the decoded 100kHz or 500kHz standard frequency signal to the electric energy meter calibration device as a reference frequency, wherein the standard frequency signal in the frequency generation module is tamed to generate 10MHz by the crystal oscillator according to the 1PPS analyzed by optical fiber transmission, and then converted by frequency division.

[0054] Specifically, the time difference and status monitoring module uses the 1PPS output by the time-frequency decoding module to perform accuracy monitoring, and at the same time transmits the operating status information and time difference information of the monitored decoding module, NTP timing module and frequency generation module back to the monitoring platform through the optical fiber loop.

[0055] Specifically, the monitoring platform displays and saves the received time difference information and equipment operation information in real time. At the same time, the monitoring platform sends this information to the production management system MES, so as to timely grasp the equipment operation status and ensure that the electricity meter calibration work is always carried out under the condition of normal equipment operation and normal time synchronization accuracy, effectively avoiding the situation where the clock is out of tolerance while the calibration is still in progress, and subsequent discovery requires rework, affecting production.

[0056] Based on the functions provided by the above modules, the working principles of the systems involved in the modules are explained:

[0057] The working principle of the above system of the present invention mainly involves three parts: (1) GNSS remote time and frequency transmission principle, (2) time encoding and decoding principle, and (3) time and frequency signal measurement and status monitoring principle.

[0058] (1) Principle of GNSS remote time and frequency transmission

[0059] In the standard time-frequency signal generation module, the standard time-frequency source uses the satellite common view principle to trace back to the reference time-frequency standard or benchmark, calculates the time difference with the reference time, and uses the calculated time difference to correct the phase and frequency difference of the internal clock to achieve synchronization with the time-frequency of the reference time. The synchronized time-frequency signal is sent to the time-frequency encoding module, which encodes the received time-frequency signal.

[0060] (2) Time signal encoding and decoding principle

[0061] In the time-frequency encoding module and the time-frequency decoding module, time coding technology is an important branch in the field of digital signal processing. It adds time information to the signal so that the original signal can be accurately restored during transmission, storage and processing. Time coding mainly includes digital time coding and analog time coding. The digital time coding is used in the present invention. The time information is modulated into pulse signals of different widths, and the whole second corresponds to a pulse signal of a special width. The encoded digital signal is transmitted using a low-latency optical fiber.

[0062] The time-frequency decoding module receives the encoded time information and needs to decode it. When decoding, it first finds the pulse signal of special width, marks it as the whole second, converts the digital code after parsing according to the agreed pulse width, forms a decimal timestamp, and then parses out the date, time and 1PPS (pulse per second) signal corresponding to the whole second. The parsed 1PPS pulse will tame the crystal oscillator to restore a frequency to keep it consistent with the reference frequency.

[0063] (3) Principles of time-frequency signal measurement and status monitoring

[0064] In the time difference and status monitoring module, the measurement of the time signal of the second pulse signal is carried out by taking the reference 1PPS signal (the decoded 1PPS signal transmitted by the optical fiber) as the opening door, and measuring the coarse clock count of the closing moment of the 1PPS signal to be measured (the 1PPS signal generated by the tamed crystal oscillator); for the count within a clock cycle, the hysteresis of the 1PPS to be measured is amplified by the linear delay circuit, and then the fine clock count is performed. The fine clock count and the coarse clock calculation are multiplied by the clock cycle to obtain different time signals, and the coarse count and the fine count results are combined to perform the difference calculation to obtain the time deviation of the final 1PPS signal, which can achieve the purpose of high-precision measurement. The measurement of the frequency signal is realized by the time difference method, and the linear slope of the time deviation within a period of time is calculated, which is the frequency deviation result, so as to measure the frequency deviation of the frequency generation module.

[0065] The network-based time measurement adopts the basic principle of network timing and uses the symmetry of network round-trip communication to calculate the network transmission delay and time offset of the master clock (time frequency standard) and the slave clock (time terminal to be measured). The master clock corresponds to the NTP timing module, and the slave clock corresponds to the electric energy meter identification device. The timing deviation between the NTP timing module and the electric energy meter verification device is monitored, and the electric energy meter verification device controlled by the NTP timing module is monitored to ensure that there is no problem.

[0066] First, the master clock sends a Synco synchronization message. When the message is sent, the physical layer adds an accurate sending timestamp T1 to the sending packet. When the slave clock receives the message, the physical layer adds an accurate receiving timestamp T2 to the receiving packet. At this time, the slave clock has timestamps T1 and T2. Secondly, the slave clock sends a delay request message Delay_Req to the master clock, and when the message is sent, the physical layer adds an accurate sending timestamp T3 to the sending packet. The slave clock records T3. At this time, the slave clock has timestamps T1, T2, and T3. Finally, when the master clock receives the delay request message Delay_Req, the physical layer adds an accurate receiving timestamp T4 to the receiving message, and sends T4 timestamp information to the slave clock through the delay response message Delay_Resp. The slave clock records the time T4. At this time, the slave clock has timestamps T1, T2, T3, and T4. The timestamp marking process is as follows: Figure 2 shown.

[0067] Since the above transmission delay is carried out at the transmission physical layer, it is only related to the distance between the two points of carrier communication. Therefore, the uplink and downlink transmission delay T delay1 and T delay2 Equal, the time delay and time offset can be calculated:

[0068] T delay =[(T2-T1)+(T4-T3)] / 2

[0069] T offset =[(T2-T1)-(T4-T3)] / 2

[0070] If the master clock uses a time and frequency standard that has been traced back to its source, then the time deviation of the slave clock can be accurately measured based on Toffset, thereby completing the absolute time value transfer of the slave clock. By calculating the time offset over a period of time, the frequency measurement characteristics such as the relative frequency deviation of the slave clock can be obtained, thereby achieving the purpose of remote measurement.

[0071] The time difference and status monitoring module transmits the collected operating status, time deviation, frequency deviation, network synchronization deviation and other information of each module (decoding module, NTP timing module and frequency generation module, etc.) back to the monitoring platform. The monitoring platform then transmits the received time and frequency measurement information and status information to the MES system, achieving real-time monitoring of timing accuracy and equipment status, and perfectly realizing the closed loop of timing and monitoring.

[0072] In view of the shortcomings of the existing technology and equipment, combined with the demand of the electric energy meter calibration device for a reference clock, the present invention introduces a clock and monitoring system used in the electric energy meter calibration device, which can achieve the following purposes:

[0073] 1. Remote real-time time tracing

[0074] The present invention uses the standard time and frequency signals traced to the national power grid through satellite common view, modulates them and transmits them using the low latency and long-distance transmission characteristics of optical fiber, and demodulates them into standard time and frequency signals that can be traced in real time required by the electric energy meter calibration device at the time and frequency timing terminal. Real-time tracing through satellite common view ensures the accuracy of timing.

[0075] 2. Timing and monitoring closed-loop system

[0076] The monitoring system of the present invention, that is, the time-frequency timing terminal, in addition to providing high-precision time-frequency signals, can also upload the working status of the time-frequency timing terminal and the real-time clock error to the monitoring platform through optical fiber, thus forming a closed-loop system of timing + monitoring. During the operation of the equipment, not only the timing accuracy of the equipment can be grasped in real time, but also the working status of the equipment can be known, effectively improving production efficiency.

[0077] 3. Improve accuracy

[0078] The present invention realizes the remote tracing of time and frequency through GNSS satellite common view and optical fiber time and frequency transmission, fundamentally ensuring the accuracy of the generated standard time and frequency signal. The time accuracy can reach 100ns and the frequency accuracy can reach 2e-11, which are both one order of magnitude better than the traditional GPS disciplined crystal oscillator, effectively improving the timing accuracy.

[0079] 4. Device application scenarios

[0080] A clock and monitoring platform used in electric energy meter calibration devices can be traced back to the time and frequency standards of the State Grid Metering Center through satellite common view technology, and then traced back to the national time and frequency measurement benchmark, forming a complete traceability link to ensure the accuracy of equipment timing. By monitoring the time difference and status of the time and frequency timing terminal, a closed loop of timing and monitoring is formed, which fundamentally solves the problem of only timing without monitoring, and the inability to grasp the occurrence of problems with equipment timing accuracy in a timely manner. The present invention belongs to the application of the terminal to the time and frequency transmission value, and the system architecture formed by it is as follows: Figure 3 shown.

[0081] At present, the time-frequency coding and monitoring module of the present invention is deployed together with the provincial standard time-frequency source. It is transmitted to the electric energy meter calibration device in the electric energy meter automatic calibration assembly line workshop through optical fiber to provide it with a time-frequency reference signal. At the same time, the internal time difference measurement and status detection module transmits the collected accuracy error and status information to the time-frequency coding and monitoring module through the optical fiber loop. The time-frequency coding and monitoring module forwards the accuracy error and status information to the monitoring platform. The monitoring platform stores the monitoring information, warns of out-of-tolerance warnings, and forwards it to the MES system, so as to facilitate real-time monitoring of the entire production process.

[0082] In the future, the present invention can also be applied to the testing of energy controllers, charging piles and other devices with electricity billing devices; these devices generally measure energy and bill based on time, and measuring timing errors is an item that needs to be tested. The present invention can be used as a clock tester to provide them with time and frequency references. Compared with traditional clock testers, it has the characteristics of high precision, real-time traceability, and monitoring, and can replace traditional clock testers.

[0083] The present invention monitors the accuracy and status of the timing module and transmits the information back to the monitoring platform through an optical fiber loop. The monitoring platform transmits the monitoring information to the MES system, thereby achieving high-precision time and frequency remote measurement and status monitoring of the time and frequency standard clock in the electric energy meter calibration, effectively avoiding the situation where the original standard clock calibrator finds out the error at the next calibration, thereby improving the efficiency of the electric energy meter calibration, improving the fairness of the calibration and realizing the effective use of energy.

[0084] As the inventive unit, the State Grid Jiangxi Marketing Service Center (Metering Center) has carried out pilot application construction. The system composition structure diagram is shown in the figure below: Figure 4 As shown. After actual field testing, pilot application, and data analysis, the present invention can achieve higher time-frequency transmission accuracy, and the frequency accuracy index is 3 orders of magnitude higher than the original standard clock, reaching an accuracy of 2E-11, which can completely replace the original standard clock. At the same time, due to the monitoring of the accuracy and status of the time-frequency timing terminal by this system, the effective monitoring of the equipment is achieved, which effectively avoids the original equipment out-of-tolerance only being known at the next calibration, which seriously affects power production. The application of this device for one year has achieved remarkable results, and the original unknown out-of-tolerance situation has not occurred, which has effectively improved production efficiency.

[0085] The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A clock and monitoring system used in an electric energy meter calibration device, characterized in that: include: Standard time-frequency signal generation module, time-frequency encoding module, time-frequency decoding module, NTP timing module, frequency generation module, time difference and status monitoring module and monitoring platform; Among them, the standard time-frequency signal generating module, the time-frequency encoding module, and the time-frequency decoding module are connected in sequence, and the time-frequency decoding module is respectively connected to the NTP timing module, the frequency generating module, and the time difference and status monitoring module; the time difference and status monitoring module is connected to the monitoring platform; The standard time-frequency signal generating module is used to obtain a time-frequency signal, wherein the time-frequency signal includes a frequency signal, a second pulse signal and a timestamp; The time-frequency encoding module is used to encode the time-frequency signal and transmit it to the time-frequency decoding module; The time-frequency decoding module is used to decode the encoding result to obtain a time-frequency signal; The NTP timing module is used to provide timing services to the electric energy meter verification device according to the timestamp; The frequency generation module is used to generate a standard frequency signal according to the pulse-per-second signal to provide a reference frequency for the electric energy meter verification device; The time difference and status monitoring module is used to monitor the time-frequency decoding module, the NTP timing module, and the frequency generation module according to the second pulse signal to obtain the operating status information and time difference information of each module; The monitoring platform is used to display and store the time difference information and the operation status signal, and transmit them to the production management system of the electric energy meter calibration device.

2. The system according to claim 1, characterized in that In the standard time-frequency signal generating module, the time-frequency signal is acquired by tracing back to the reference time-frequency standard through the satellite common-view method.

3. The system according to claim 1, characterized in that The time-frequency encoding module is connected to the time-frequency decoding module via an optical fiber.

4. The system according to claim 1, characterized in that In the time-frequency encoding module, the time-frequency signal is encoded by a digital time encoding method.

5. The system according to claim 1, characterized in that The time difference information includes a time deviation signal, a frequency deviation signal, a time delay signal and a time offset signal.

6. The system according to claim 5, characterized in that In the time difference and state monitoring module, monitoring the frequency generation module includes measuring the second pulse signal, wherein the process of measuring the second pulse signal includes: taking the second pulse signal as the opening door, measuring the second pulse signal to be measured of the crystal oscillator in the frequency generation module as the coarse clock count at the closing moment, obtaining the count within a clock cycle, amplifying the hysteresis of the second pulse signal to be measured by a linear delay circuit, and then performing a fine clock count, and obtaining the time deviation signal of the second pulse signal according to the coarse clock count and the fine clock count.

7. The system according to claim 6, characterized in that In the time difference and status monitoring module, monitoring the frequency generation module also includes measuring the frequency signal, wherein the process of measuring the frequency signal includes: calculating the linear slope of the time deviation signal at a fixed time of the electric energy meter calibration device by the time difference method to obtain the frequency deviation signal.

8. The system according to claim 5, characterized in that In the time difference and status detection module, monitoring the NTP timing module includes monitoring network synchronization, wherein the process of monitoring network synchronization includes: using the NTP timing module as the master clock and the electric energy meter calibration device as the slave clock, performing time delay and time offset calculations on the master clock and the slave clock through the network timing principle to obtain a time delay signal and a time offset signal.

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