Electric energy meter and metering terminal clock field detection method and system

Abstract

The application discloses an electric energy meter and a meter terminal clock field detection method and system, relates to the technical field of timing and synchronization, and comprises a clock calibrator GPS-7A system which is constructed and intercepts high-voltage signals for overload protection during data acquisition; converts the optocoupler on-off signal output by the electric energy meter into an identifiable electrical signal, and acquires standard time by using a GPS & Beidou receiver; measures the daily timing error of the electric energy meter and the overtime, and forcibly synchronizes the electric energy meter with the local time for timing by using high-precision local time. The application guarantees the interests of the power department and the power consumer, acquires more accurate matching parameters by matching the crystal oscillator and the load capacitor through the measurement of the daily timing error, simultaneously accesses two-way electric energy meters to improve the test efficiency, more quickly screens qualified products, effectively prevents the problem that the user mistakenly connects the 220V power supply to the test port, fully protects the core circuit of the equipment, effectively reduces the equipment failure rate, and provides a good use experience for the user.

Description

Technical Field

[0001] This invention relates to the field of timing and synchronization technology, specifically to a method and system for on-site detection of clocks in electricity meters and metering terminals. Background Technology

[0002] Electricity meters play a prominent role in current power operations. The accuracy of their clocks directly affects the settlement of tariffs and is related to the interests of both the power supplier and the electricity consumer.

[0003] With the continuous development of the power industry, electricity metering has become a crucial component of the electricity marketing system. Currently, clock deviation is a major issue affecting the accuracy of electricity meters. Only by effectively controlling clock deviation and improving its accuracy can the safe operation of electricity meters be maintained and their precise metering function fully realized. Therefore, power supply companies need to strive for excellence, clearly identify the causes and influencing factors of clock deviation, explore solutions, further improve calibration quality, ensure more accurate metering and more reliable operation of electricity meters, and safeguard the economic interests of both power suppliers and consumers.

[0004] Domestic electricity meter timing methods are divided into two types: independent clock chips and microcontroller-integrated clock modules. The latter has a greater cost advantage and is therefore more widely used. Microcontroller-integrated clock modules primarily provide clock services. Users can set and read the values ​​of their internal timing registers, and the system will automatically keep track of time, typically outputting clock pulses in seconds. Crystal oscillators below 20MHz offer good stability; those above 20MHz mostly produce harmonics and have poor stability. In the event of a power outage, the electricity meter's clock module is powered by a battery. To achieve low-power, stable operation, the clock source must be a low-frequency crystal oscillator with a small drive current. Tuning fork crystal oscillators typically have frequencies between 10 and 200kHz, with 32.768kHz being commonly used.

[0005] The main factors affecting the accuracy of electricity meter timing include: crystal oscillator, matching capacitor, battery, etc.

[0006] ① Crystal Oscillator: The oscillation frequency of a quartz crystal changes with temperature, a phenomenon known as its temperature characteristic. Due to this characteristic, the accuracy of the clock chip will deviate with temperature changes, and different crystal oscillators have different temperature characteristics. Through batch testing, the vertex deviations of different crystals vary significantly, requiring measurement during calibration and compensation based on the deviation differences to maintain the accuracy of the clock chip.

[0007] ② Matching capacitor: The actual oscillation frequency of a passive crystal depends not only on the crystal itself, but also on the size of the matching capacitor. Fine adjustment of the matching capacitor is required to ensure that the clock runs within the allowable error range.

[0008] ③ Battery: The battery is also a significant factor causing deviations. The clock battery in the electricity meter powers the RTC (Real-Time Clock) module. When powered by an external power source, the battery voltage is typically 3.3V (or 5V). Based on current usage, China Southern Power Grid stipulates that the battery voltage should exceed 2.7V under normal conditions for normal operation. When the battery voltage drops below 2.7V, the electricity meter's accumulated charge will be erroneous, requiring battery replacement. After battery replacement, the clock needs to be recalibrated, and any lost data from the electricity meter must be processed.

[0009] To address the measurement of timing errors in electricity meters, a device was developed that detects daily timing errors and measures overtime. This device can measure the daily timing error of electricity meters and, based on the user-set overtime time, determine the number of overtime days, providing further suggestions for meter replacement or time calibration. Furthermore, the device integrates the broadcast time calibration function of the DLT645-2007 State Grid multi-functional electricity meter communication protocol, facilitating time calibration for users and further realizing intelligent management of electricity meter clock verification. Summary of the Invention

[0010] In view of the aforementioned existing problems, this invention addresses the issue that when the electricity meter clock is accurate, it may time out again, requiring on-site maintenance and increasing the number of maintenance personnel required. This device checks whether the electricity meter clock meets the specified requirements and provides a prediction of the timeframe in which clock timeout may occur. Based on the inspection, it determines whether to replace the electricity meter, reducing the number of maintenance operations required for on-site handling of clock anomalies and ensuring that clock timeout issues do not recur shortly after on-site handling of clock anomalies.

[0011] To address the aforementioned technical issues, a method for on-site testing of the clock of electricity meters and metering terminals is proposed, including:

[0012] A GPS-7A clock calibrator system was constructed, and high-voltage signals were intercepted during data acquisition for overload protection. The optocoupler on / off signals output by the electricity meter were converted into recognizable electrical signals, and standard time was obtained using a GPS & Beidou receiver. The daily timing error and overtime of the electricity meter were measured, and the high-precision local time was used to force the electricity meter to synchronize with the local time for time calibration.

[0013] As a preferred embodiment of the on-site detection method for the clock of the energy meter and metering terminal described in this invention, the overload protection includes: using two energy meter optocoupler output signals for input; when 220V power frequency AC is connected to the instrument input port, the instrument protection module is activated; the forward voltage is intercepted by a high-voltage diode and connected to the signal input terminal in reverse; a current-limiting resistor and a Zener diode are added after the high-voltage diode; when the negative half-cycle voltage of 220V power frequency enters the input port, the instrument protection module limits the current through the current-limiting resistor and limits the amplitude through the Zener diode before entering the shaping circuit.

[0014] When the optocoupler output of the energy meter is correctly connected to the instrument input terminal, the optocoupler inside the energy meter will output a 1Hz on / off signal. When the optocoupler output of the energy meter is on, the signal is shaped into a square wave and sent to the MCU for sampling and calculation.

[0015] As a preferred embodiment of the on-site detection method for the clock of the electricity meter and metering terminal described in this invention, the signal shaping includes converting the 1Hz optocoupler on / off signal output by the electricity meter into an LVTTL 3.3V electrical signal recognizable by the MCU, and when the optocoupler is on and off, the positive voltage of the operational amplifier is on both sides of the negative input reference voltage.

[0016] When the optocoupler outputs an ON signal from the energy meter, the operational amplifier outputs a low level when the voltage is below 7V. When the optocoupler outputs an OFF signal from the energy meter, the operational amplifier outputs a high level when the voltage is above 7V. A resistor network is used to divide the voltage to obtain an LVTTL 3.3V signal, which is then sent to the MCU capture port.

[0017] As a preferred embodiment of the on-site clock detection method for electricity meters and metering terminals described in this invention, the standard time includes: acquiring standard time using a GPS & Beidou receiver, adding the rising edge of the PPS signal to indicate the whole second of UTC, receiving beacon information sent by GPS with extremely high precision time difference through the receiver, and counting ticks of its own clock within a specified time. After the receiver synchronizes with the GPS clock, it outputs a PPS signal and a complete clock waveform every second according to its own calibrated clock, and synchronizes and locks all clocks in the computer.

[0018] As a preferred embodiment of the on-site clock detection method for electricity meters and metering terminals described in this invention, the measurement of daily timing error and the measurement of timeout time include: the MCU sampling the signal output from the signal shaping process, counting by controlling a counter to obtain the count value of standard time pulses within one signal cycle, and the microprocessor acquiring and calculating the daily timing error.

[0019]

[0020] Where Dd is the standard daily deviation value, f0 is the nominal value of the center frequency of the daily deviation signal, and f1 is the actual frequency value of the signal being tested.

[0021] The MCU samples the shaped second pulse electrical signal and records and saves the two rising edges of a complete second pulse cycle. The MCU counter captures the timer value N1 when the first rising edge of the second pulse arrives and the counter value N2 when the second rising edge of the second pulse arrives. Then, N2-N1 is the total number of counter counts between the two rising edges of the second pulse.

[0022] If the MCU sampling frequency is F, then the time interval for each count is 1 / F seconds. The actual time interval between the rising edges of two sampled pulses is... Seconds, corresponding to a frequency of

[0023] Calculate the timeout period Td:

[0024]

[0025] Among them, T curr The current clock reading is γ, which controls the rate of exponential decay, T is the time variable, and Θ(Dd) is used to adjust the daily timing error.

[0026] Based on the timekeeping error measured during testing, the GPS-7A determines whether to replace the watch. If Dd ≤ 0.5s / d, it is recommended not to replace the watch.

[0027] However, if Dd > 0.5s / d, the timeout period Td will be calculated and displayed based on the user-set timeout parameter. If Td ≤ the user-set timeout parameter, it is recommended not to change the table. If Td > the user-set timeout parameter, a table change suggestion will be given.

[0028] As a preferred embodiment of the on-site clock detection method for electricity meters and metering terminals described in this invention, the time calibration includes the GPS-7A clock calibrator's time calibration module simultaneously employing both infrared and RS485 time calibration schemes, and using sensors to monitor the surrounding environmental conditions in real time to assess the current time calibration environment.

[0029]

[0030] Where k is the weighting coefficient of the obstacle's influence on the signal, a is the distance between the device and the time source, ob is the number of obstacles in the path that obstruct the signal, and s is the measured GPS / BeiDou signal strength.

[0031] Based on the environmental assessment results, the time synchronization method is selected: when E>1, infrared time synchronization is selected, and infrared signals are used for time synchronization to ensure that there are no significant obstacles between the two devices.

[0032] When E≤1, select RS485 time synchronization to perform time synchronization in situations with signal interference or long distance.

[0033] After selecting a time synchronization scheme, update the time to calculate the time deviation and synchronize the time.

[0034] Another objective of this invention is to provide an on-site detection system for the clock of an electricity meter and metering terminal. This invention addresses how to protect equipment ports and personnel safety, avoiding equipment damage and personal injury caused by wiring errors or misconnection of voltage lines. It also improves the timing accuracy of the electricity meter clock and reduces daily timing errors. This invention solves the problems of insufficient equipment protection, low timing accuracy, low time calibration efficiency, and complex operation in the prior art, thereby ensuring the fairness and reliability of electricity metering and improving the system's ease of operation and human-computer interaction experience.

[0035] As a preferred embodiment of the on-site detection system for the electricity meter and metering terminal clock described in this invention, it is characterized by including a signal preprocessing module, a daily timing error / overtime measurement module, and a time calibration module.

[0036] The signal preprocessing module completes the input protection of the device port, the shaping of the output signal of the energy meter optocoupler, and the acquisition of the standard second pulse signal of the GPS & Beidou receiver.

[0037] The daily timing error / timeout measurement module measures the four 1Hz signals obtained from the signal preprocessing module to obtain the daily timing error and timeout.

[0038] The time synchronization module outputs broadcast time synchronization commands that conform to the DLT645-2007 State Grid multi-function energy meter communication protocol, including infrared mode and RS485 mode.

[0039] As a preferred embodiment of the on-site clock detection system for electricity meters and metering terminals described in this invention, the signal preprocessing module includes an antenna interface and a BeiDou & GPS timing unit, and an electricity meter optocoupler input shaping and input protection unit. The antenna interface and BeiDou & GPS timing unit obtains standard time through GPS and BeiDou satellite synchronization, performing time synchronization and clock verification functions on the electricity meter. The electricity meter optocoupler input shaping and input protection unit receives second pulse inputs from four electricity meters. The second pulse output from the electricity meters is an unconventional electrical signal, which is then converted into an electrical signal for measurement. In case of wiring errors or incorrect voltage line connections, the system protects the equipment and personnel from damage.

[0040] The daily timing error / overtime measurement module includes a high-precision temperature-compensated crystal oscillator unit that uses a high-stability, high-frequency standard pulse signal to send to the MCU and the second pulse signal of the energy meter for calculation and processing to determine the daily timing error and overtime days of the energy meter.

[0041] The time synchronization module includes a central processing unit and data processing unit, an interaction unit, a display unit, an output unit, and a power management unit. The central processing unit and data processing unit use a 32-bit high-frequency processor to analyze data and perform inter-module communication. The interaction unit is the device's input interface, allowing users to select test parameters via a touchscreen. The display unit displays the device's test modes and measurement results, enabling human-machine interaction. The output unit outputs 10MHz, 1MHz, 1kHz, and 1Hz signals. The power management unit serves as the device's power unit, providing power to the device.

[0042] A computer device includes a memory and a processor, wherein the memory stores a computer program, characterized in that the processor executes the computer program to implement the steps of the on-site detection method for the clock of the electricity meter and metering terminal.

[0043] A computer-readable storage medium having a computer program stored thereon, characterized in that, when the computer program is executed by a processor, it implements the steps of the on-site detection method for the clock of the energy meter and metering terminal.

[0044] The beneficial effects of this invention are as follows: This invention combines microprocessor technology and digital signal processing technology to measure the daily timing error and overtime of electricity meters. The overtime parameter can be set by the user. As a fully digital, multifunctional, high-precision, and intelligent multi-parameter time error measurement device, it provides technical support and assurance for electricity meter manufacturers in developing and mass-producing electricity meters, and provides objective and impartial evidence for power departments and electricity customers, thus protecting the interests of both parties.

[0045] During the research and development and production stage of electricity meters, the crystal oscillator and load capacitor can be matched by measuring the daily timing error to obtain more accurate matching parameters. During the batch testing stage, the simultaneous connection of two electricity meters can significantly improve testing efficiency and screen qualified products more quickly. Frontline staff of the power grid can simultaneously complete multiple tasks such as daily timing error testing, overtime testing, and electricity meter time calibration, thereby improving testing efficiency.

[0046] It effectively prevents users from accidentally connecting 220V power to the test port, provides full protection for the core circuit of the equipment, effectively reduces the equipment failure rate, and provides users with a good user experience.

[0047] The test results are presented in a very intuitive and concise way, without the need for complicated and tedious operations, with a low learning curve and easy to get started. Attached Figure Description

[0048] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein:

[0049] Figure 1 This is a flowchart illustrating a mobile inspection process for an on-site clock detection method for an energy meter and metering terminal, as provided in an embodiment of the present invention.

[0050] Figure 2 Signal and modulation of an on-site clock detection method for an energy meter and metering terminal provided in one embodiment of the present invention.

[0051] Figure 3 The light radiation angle of the on-site detection method for the clock of the energy meter and metering terminal provided in one embodiment of the present invention.

[0052] Figure 4 This is a system scheme module diagram of an on-site detection system for an electricity meter and metering terminal clock provided in one embodiment of the present invention.

[0053] Figure 5 This is a system interface structure diagram of an on-site clock detection system for an energy meter and metering terminal provided in one embodiment of the present invention. Detailed Implementation

[0054] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0055] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0056] Secondly, the term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places throughout this specification does not necessarily refer to the same embodiment, nor is it an embodiment that is mutually exclusive, either alone or selectively, with other embodiments.

[0057] This invention is described in detail with reference to the schematic diagrams. When detailing the embodiments of this invention, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged, not adhering to the usual scale. Furthermore, the schematic diagrams are merely examples and should not be construed as limiting the scope of protection of this invention. In actual fabrication, the three-dimensional spatial dimensions of length, width, and depth should be included.

[0058] Furthermore, in the description of this invention, it should be noted that the terms "upper," "lower," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are used solely for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. In addition, the terms "first," "second," or "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0059] Unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" in this invention should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integrated connections; similarly, they can refer to mechanical connections, electrical connections, or direct connections, or indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0060] Example 1, referring to Figure 1 This is the first embodiment of the present invention, which provides a method for on-site detection of the clock of an energy meter and a metering terminal, including:

[0061] S1: Construct a GPS-7A clock calibrator system and intercept high-voltage signals for overload protection during data acquisition.

[0062] Furthermore, a two-channel optocoupler output signal is used for input. When 220V AC power is connected to the instrument input port, the instrument protection module is activated. The forward voltage is intercepted by a high-voltage diode and connected to the signal input terminal in reverse. A current-limiting resistor and a Zener diode are added after the high-voltage diode. When the negative half-cycle voltage of 220V AC power enters the input port, the instrument protection module limits the current through the current-limiting resistor and limits the amplitude through the Zener diode before entering the shaping circuit.

[0063] It supports the input of two optocoupler output signals from electricity meters, improving testing efficiency. Conventional devices for testing the daily timing error of electricity meters only connect to one meter, resulting in low testing efficiency. Simultaneously, through the GPS & BeiDou time synchronization module, it synchronously displays standard Beijing time, allowing real-time monitoring of the electricity meter's clock timing error.

[0064] First, a high-voltage diode is used to intercept the forward voltage. Here, a 700V high-voltage diode is selected and connected in reverse to the signal input terminal. This ensures that the 220V power frequency positive half-cycle high voltage cannot enter the instrument, and only the negative half-cycle high voltage can enter the equipment. The parameters of the high-voltage diode selected here have a margin. The peak value of the 220V power frequency voltage is 220*1.414=311V. Even if the energy meter is powered by 380V, the peak value is 380*1.414=537V, which is still within the 700V withstand voltage range, and can still play a role in circuit protection.

[0065] Secondly, a current-limiting resistor and a Zener diode are added after the high-voltage diode. When the negative half-cycle voltage of the 220V power frequency enters the input port, the module's current is limited by the current-limiting resistor and the amplitude is limited by the Zener diode before entering the shaping circuit. In this way, the voltage obtained by the negative half-cycle voltage of the 220V power frequency entering the subsequent signal shaping circuit is only the 0.6V voltage drop of the diode. At this time, the negative half-cycle voltage of the 220V power frequency is applied to the current-limiting resistor, so it will not cause damage to the shaping circuit and the MCU, thus playing a protective role.

[0066] When the optocoupler output of the energy meter is correctly connected to the instrument input terminal, the optocoupler inside the energy meter will output a 1Hz on / off signal. When the optocoupler output of the energy meter is on, the signal is shaped into a square wave and sent to the MCU for sampling and calculation.

[0067] Conventional test circuits can only accept low-voltage inputs, in the volt range. Based on past experience testing daily timing errors in electricity meters, over 90% of failures are caused by operator error. Electricity meters have a 220V AC input, which can easily be accidentally touched, leading to damage to the MCU port and shaping circuitry. Through a cleverly designed protection circuit, when the test port is accidentally touched by 220V AC power, the high-voltage signal is intercepted within the protection circuit, preventing it from entering the shaping circuitry and MCU port, thus protecting the core circuitry.

[0068] It should be noted that the 1Hz optocoupler on / off signal output by the energy meter is converted into an LVTTL 3.3V electrical signal that the MCU can recognize. The on / off circuit of the optocoupler output of the energy meter is used to control the positive voltage of the operational amplifier. During the design, it is ensured that the positive voltage of the operational amplifier is on both sides of the negative input reference voltage when the optocoupler is on and off.

[0069] When the optocoupler outputs an ON signal from the energy meter, the operational amplifier outputs a low level when the voltage is below 7V. When the optocoupler outputs an OFF signal from the energy meter, the operational amplifier outputs a high level when the voltage is above 7V. A resistor network is used to divide the voltage to obtain an LVTTL 3.3V signal, which is then sent to the MCU capture port.

[0070] S2: Convert the optocoupler on / off signal output by the electricity meter into a recognizable electrical signal, and obtain standard time using a GPS & Beidou receiver.

[0071] Furthermore, by using GPS and BeiDou receivers to obtain standard time and adding the rising edge of the PPS signal to indicate the whole second in UTC, the accuracy can reach the nanosecond level, and there is no cumulative error. GPS uses atomic clocks, which are devices that use the extremely stable electromagnetic waves emitted by atoms when they absorb or release energy to keep time, and the accuracy can reach 1 second of error every 20 million years.

[0072] The receiver receives beacon information transmitted by GPS with extremely high precision time differences and counts ticks on its own clock within a specified time. It compares the count value with the theoretical number of ticks generated in the same time period at the nominal frequency, and uses hardware to adjust its own crystal oscillator frequency accordingly, achieving precise frequency correction over several consecutive second pulse cycles. After synchronizing with the GPS clock, the receiver outputs a PPS signal and a complete clock waveform every second based on its calibrated clock, and synchronizes and locks all clocks in the computer.

[0073] To obtain highly accurate and more stable PPS (Pulse Per Second), an imported UBLOX receiver module is used, and an active antenna is selected to enhance signal reception. The GPS & BeiDou module is an outdoor module; its performance is very weak and poor indoors. Handheld devices need to be taken to an open outdoor location for time synchronization to better acquire GPS & BeiDou signals.

[0074] The GPS-7A clock calibrator also offers a more intuitive method for measuring time difference. The device can directly obtain the real-time time information from the electricity meter using infrared communication and display it on a 4.3-inch touchscreen. This allows users to visually compare the standard time on the clock calibrator with the actual time on the electricity meter under test to obtain the time error value.

[0075] S3: Measure the daily timing error and overtime of the electricity meter, and use the high-precision local time to force the electricity meter to synchronize with the local time for time calibration.

[0076] Furthermore, the MCU samples the signal output after signal shaping and controls a counter to count the standard time pulses within one signal cycle. The microprocessor then collects and calculates the daily timing error.

[0077]

[0078] Where Dd is the standard daily deviation value, f0 is the nominal value of the center frequency of the daily deviation signal, and f1 is the actual frequency value of the signal being tested.

[0079] The MCU samples the shaped second pulse electrical signal and records and saves the two rising edges of a complete second pulse cycle. The MCU counter captures the timer value N1 when the first rising edge of the second pulse arrives and the counter value N2 when the second rising edge of the second pulse arrives. Then, N2-N1 is the total number of counter counts between the two rising edges of the second pulse.

[0080] If the MCU sampling frequency is F, then the time interval for each count is 1 / F seconds. The actual time interval between the rising edges of two sampled pulses is... Seconds, corresponding to a frequency of

[0081] Calculate the timeout period Td:

[0082]

[0083] Among them, T curr The current clock reading is γ, which controls the rate of exponential decay, T is the time variable, and Θ(Dd) is used to adjust the daily timing error.

[0084]

[0085] Among them, T interval Let P(t) be the actual time interval, P(t) be the function controlling external disturbances, and G(t) be the rate of change of time.

[0086]

[0087] Wherein, λ is a parameter representing the degree of filtering, which determines the extent of error smoothing.

[0088] Based on the timekeeping error measured during testing, the GPS-7A determines whether to replace the watch. If Dd ≤ 0.5s / d, it is recommended not to replace the watch.

[0089] However, if Dd > 0.5s / d, the timeout period Td will be calculated and displayed based on the user-set timeout parameter. If Td ≤ the user-set timeout parameter, it is recommended not to change the table. If Td > the user-set timeout parameter, a table change suggestion will be given.

[0090] It should be noted that the GPS-7A clock calibrator's time synchronization module employs both infrared and RS485 time synchronization methods, using sensors to monitor the surrounding environmental conditions in real time and assess the current time synchronization environment.

[0091]

[0092] Where k is the weighting coefficient of the obstacle's influence on the signal, a is the distance between the device and the time source, ob is the number of obstacles in the path that obstruct the signal, and s is the measured GPS / BeiDou signal strength.

[0093] Based on the environmental assessment results, the time synchronization method is selected: when E>1, infrared time synchronization is selected, and infrared signals are used for time synchronization to ensure that there are no significant obstacles between the two devices.

[0094] When E≤1, select RS485 time synchronization to perform time synchronization in situations with signal interference or long distance.

[0095] After selecting a time synchronization plan, the update time will be:

[0096] T new =T curr +(T source -T curr )·α

[0097] Among them, T new For the updated time, T curr T represents the current time. source is the source time, represents the target time to be referenced, and α is a weighting coefficient that controls the smoothness of the update.

[0098] Record the current time of the electricity meter and calculate the deviation:

[0099] ΔT=T new -(T source -T curr )·(1-β)

[0100] Where ΔT represents the time deviation, that is, the difference between the updated time and the current time, and β is the adjustment coefficient.

[0101] The system calculates the accuracy of time synchronization:

[0102]

[0103] Here, Accuracy represents the accuracy of the calculation system output, and factor is the adjustment coefficient that affects the accuracy assessment.

[0104] Example 2, refer to Figures 2-3 As an embodiment of the present invention, a method for calculating the sensitivity of a three-phase four-wire low-voltage AC / DC distribution network is provided. To verify the beneficial effects of the present invention, scientific demonstration is carried out through experiments.

[0105] Infrared time synchronization uses infrared transmitters and receivers to communicate with the electricity meter and uses a broadcast time synchronization scheme for time synchronization.

[0106] ①Modulation characteristics

[0107] For signal modulation, see Figure 2 , where a is the unmodulated electrical signal and b is the modulated infrared light signal.

[0108] The carrier frequency is 38kHz±1kHz.

[0109] ② Optical properties: Reference temperature is 23℃±2℃.

[0110] ③ Half-angle of light radiation: θ≥15°.

[0111] ④ Wavelength: Infrared wavelength is 900nm~1000nm.

[0112] Transmitter: The irradiance of the infrared light signal generated by the transmitter at a distance of 1m ± 10mm from the transmitter surface along its optical axis:

[0113] In the ON state, Ee / T ≥ 250 μW / cm 2

[0114] The irradiance of the infrared light signal generated by the transmitter at a distance of 10mm ± 1mm ​​from the transmitter surface along its optical axis is:

[0115] In the OFF state, Ee / T ≤ 1 μW / cm 2

[0116] Receiver: The infrared irradiance Ee / R at a distance of 10mm ± 1mm ​​from the receiver surface along its optical axis should meet the following conditions:

[0117] In the ON state, Ee / R ≥ 3.5 μW / cm 2

[0118] In the OFF state, Ee / R ≤ 2μW / cm 2

[0119] ⑤ Optical environment conditions: When the ambient light intensity around the optical path for data transmission is less than 5000 lx, the effective communication distance is greater than 3m.

[0120] ⑥ Electrical characteristics: Default rate: 1200bps.

[0121] The RS485 time synchronization scheme uses an RS485 interface to communicate with the electricity meter, and also uses a broadcast scheme for time synchronization.

[0122] Consistent with the communication protocol of the State Grid DLT645-2007 multi-functional energy meter, the GPS-7A clock calibrator uses an RS-485 standard serial electrical interface, enabling multi-point connections. The general performance of the RS-485 interface meets the following requirements:

[0123] Common-mode input voltage: -7V to +12V.

[0124] Differential input voltage: greater than 0.2V.

[0125] Drive output voltage: Maximum 5V, minimum 1.5V with a load impedance of 54Ω.

[0126] Three-state output.

[0127] Half-duplex communication mode.

[0128] The driving capability is no less than 32 similar interfaces.

[0129] Default rate: 2400bps. Under the condition that the communication rate is no more than 100kbps, the effective transmission distance is no less than 1200m.

[0130] The bus is passive and is powered by an isolated power source provided by a multifunction energy meter or data terminal.

[0131] The GPS-7A clock calibrator is specified as follows:

[0132] Table 1

[0133]

[0134]

[0135] Example 3, the third embodiment of the present invention, differs from the previous two embodiments in that:

[0136] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0137] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device.

[0138] More specific examples of computer-readable media (a non-exhaustive list) include: electrical connections (electronic devices) having one or more wires, portable computer disk drives (magnetic devices), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Furthermore, computer-readable media can even be paper or other suitable media on which the program can be printed, because the program can be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in computer memory.

[0139] It should be understood that various parts of the present invention can be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0140] Example 4, refer to Figures 4-5 This is the fourth embodiment of the present invention. This embodiment provides an on-site detection system for the clock of an energy meter and metering terminal, including a signal preprocessing module 10, a daily timing error / overtime measurement module 20, and a time calibration module 30.

[0141] The signal preprocessing module 10 completes the input protection of the device port, the shaping of the output signal of the energy meter optocoupler, and the acquisition of the standard second pulse signal of the GPS & Beidou receiver.

[0142] The signal preprocessing module 10 includes an antenna interface and a BeiDou & GPS timing unit 11, and an energy meter optocoupler input shaping and input protection unit 12. The antenna interface and BeiDou & GPS timing unit 11 obtain standard time through GPS and BeiDou satellite synchronization, performing time synchronization and clock verification functions for the energy meters. The energy meter optocoupler input shaping and input protection unit 12 receives the second pulse input from four energy meters. The second pulse output from the energy meters is an unconventional electrical signal, which is then converted into an electrical signal for measurement. In case of wiring errors or incorrect voltage line connections, the module protects the equipment and personnel from damage.

[0143] The daily timing error / timeout measurement module 20 measures the four 1Hz signals to be tested obtained from the signal preprocessing module 10 to obtain the daily timing error and timeout.

[0144] The daily timing error / overtime measurement module 20 includes a high-precision temperature-compensated crystal oscillator unit 21. It uses a high-stability, high-frequency standard pulse signal to send to the MCU and the second pulse signal of the energy meter for calculation and processing to determine the daily timing error and overtime days of the energy meter.

[0145] The time synchronization module 30 outputs broadcast time synchronization commands that conform to the DLT645-2007 State Grid multi-function energy meter communication protocol, including infrared mode and RS485 mode.

[0146] The time synchronization module 30 includes a central processing unit and data processing unit 31, an interaction unit 32, a display unit 33, an output unit 34, and a power management unit 35. The central processing unit and data processing unit 31 use a 32-bit high-frequency processor to analyze data and perform inter-module communication. The interaction unit 32 is the device's input interface, allowing users to select test parameters via a touchscreen. The display unit 33 displays the device's test mode and measurement results, enabling human-machine interaction. The output unit 34 outputs 10MHz, 1MHz, 1kHz, and 1Hz signals. The power management unit 35 serves as the device's power unit, providing power to the device.

[0147] Among them, system interfaces such as Figure 4 As shown:

[0148] 1 is the power switch: used to turn the GPS-7A clock calibrator on or off.

[0149] 2 is a Type-C charging port: used to charge the internal battery of the GPS-7A clock calibrator.

[0150] 3 is the infrared communication interface: used for infrared time calibration of the electricity meter.

[0151] 4 is the GPS & Beidou antenna interface: used to connect GPS & Beidou antennas to synchronize the internal real-time clock.

[0152] 5 is a 1-channel signal input port: used to connect the 1Hz output of the energy meter optocoupler of the first channel.

[0153] 6 is a 2-channel signal input port: used to connect the 1Hz output of the energy meter optocoupler for the second channel.

[0154] 7 is a 2-channel ground wire interface: used to connect the 1Hz output ground wire of the second channel of the energy meter optocoupler.

[0155] 8-to-1 ground interface: used to connect the 1Hz output ground wire of the energy meter optocoupler of the first channel.

[0156] 9 is the 485 communication B interface: Connects to the 485 communication B interface of the electricity meter for 485 time synchronization.

[0157] 10 is the 485 communication A interface: Connects to the 485 communication A interface of the electricity meter for 485 time synchronization.

[0158] 11 is the PPS signal output: outputs a 1PPS signal from the GPS & Beidou module for metrological verification.

[0159] 12 is the ground interface: the ground terminal for output signals.

[0160] 13 is a 10MHz output port: outputs a 10MHz signal for metrological verification.

[0161] 14 is a 1MHz output port: outputs a 1MHz signal for metrological verification.

[0162] 15 is a 1KHz output port: outputs a 1KHz signal for metrological verification.

[0163] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for on-site testing of the clock of an electricity meter and metering terminal, characterized in that: include, Construct a GPS-7A clock calibrator system and intercept high-voltage signals for overload protection during data acquisition; The optocoupler on / off signal output by the electricity meter is converted into a recognizable electrical signal, and the standard time is obtained using a GPS & Beidou receiver; The daily timing error and overtime of the electricity meter are measured, and the high-precision local time is used to force the electricity meter to synchronize with the local time for time calibration. The measurement of daily timing error and timeout includes sampling the signal output by the MCU after signal shaping, counting by controlling a counter to obtain the count value of standard time pulses within one signal cycle, and then the microprocessor collects and calculates the daily timing error. ； Where Dd is the standard daily deviation. This is the nominal value of the center frequency of the diurnal variation signal. The actual frequency value of the signal being tested; The MCU samples the shaped second pulse electrical signal, records and saves the two rising edges of a complete second pulse cycle, and uses the MCU counter to capture the timer value when the first rising edge of the second pulse arrives. The value of the counter when the second rising edge of the second pulse arrives. ,but This is the total number of counts made by the counter between the two rising edges of the second pulse; If the MCU sampling frequency is F, then the time interval for each count is 1 / F seconds. The actual time interval between the rising edges of two sampled pulses is... Seconds, corresponding to a frequency of Hz; Calculate timeout : ； in, Read the value of the current clock. To control the rate of exponential decay, T is a time variable. To adjust for daily timing errors; Based on the timekeeping error measured during testing, the GPS-7A determines whether to replace the watch. If Dd ≤ 0.5s / d, it is recommended not to replace the watch. However, if Dd > 0.5s / d, the timeout time Td will be calculated and displayed based on the user-set timeout parameter. If Td ≤ the user-set timeout parameter, it is recommended not to change the table. If Td > the user-set timeout parameter, a table change suggestion will be given. The time synchronization includes the GPS-7A clock calibrator's time synchronization module employing both infrared and RS485 time synchronization schemes. It uses sensors to monitor the surrounding environmental conditions in real time and assess the current time synchronization environment. ； Where k is the weighting coefficient of the obstacle's influence on the signal, and a is the distance between the device and the time synchronization source. This represents the number of obstacles in the path that impede the signal. The measured GPS / BeiDou signal strength; Based on the environmental assessment results, the time synchronization method is selected: when E>1, infrared time synchronization is selected, and infrared signals are used for time synchronization to ensure that there are no significant obstacles between the two devices. When E≤1, RS485 time synchronization is selected to perform time synchronization in cases of signal interference or long distance. After selecting a time synchronization scheme, update the time to calculate the time deviation and synchronize the time.

2. The on-site detection method for the clock of the electricity meter and metering terminal as described in claim 1, characterized in that: The overload protection includes using two-channel energy meter optocoupler output signals for input. When 220V power frequency AC is connected to the instrument input port, the instrument protection module is activated. The positive voltage is intercepted by a high-voltage diode and connected to the signal input terminal in reverse. A current-limiting resistor and a Zener diode are added after the high-voltage diode. When the negative half-cycle voltage of 220V power frequency enters the input port, the instrument protection module limits the current through the current-limiting resistor and limits the amplitude through the Zener diode before entering the shaping circuit. When the optocoupler output of the energy meter is correctly connected to the instrument input terminal, the optocoupler inside the energy meter will output a 1Hz on / off signal. When the optocoupler output of the energy meter is on, the signal is shaped into a square wave and sent to the MCU for sampling and calculation.

3. The on-site detection method for the clock of the electricity meter and metering terminal as described in claim 2, characterized in that: The signal shaping includes converting the 1Hz optocoupler on / off signal output by the energy meter into an LVTTL 3.3V electrical signal that the MCU can recognize, and when the optocoupler is on and off, the positive voltage of the operational amplifier is on both sides of the negative input reference voltage. When the optocoupler of the energy meter outputs an ON signal, the operational amplifier outputs a low level when the voltage is below 7V; when the optocoupler outputs an OFF signal, the operational amplifier outputs a high level when the voltage is above 7V. The voltage is then divided using a resistor network to obtain an LVTTL 3.3V electrical signal, which is then sent to the MCU capture port.

4. The on-site detection method for the clock of the electricity meter and metering terminal as described in claim 3, characterized in that: The standard time includes: acquiring standard time using GPS & BeiDou receivers; adding the rising edge of the PPS signal to indicate the whole second of UTC; receiving beacon information sent by GPS with extremely high precision time difference intervals through the receiver; counting ticks on its own clock within a specified time; after the receiver synchronizes with the GPS clock, it outputs the PPS signal and the complete clock waveform every second according to its own calibrated clock, and synchronizes and locks all clocks in the computer.

5. A system employing the on-site detection method for the clock of an energy meter and metering terminal as described in any one of claims 1 to 4, characterized in that: Includes a signal preprocessing module, a daily timing error / timeout measurement module, and a time calibration module; The signal preprocessing module completes the device port input protection, the shaping of the output signal of the energy meter optocoupler, and the acquisition of the standard second pulse signal of the GPS & Beidou receiver. The daily timing error / timeout measurement module measures the four 1Hz signals to be tested obtained from the signal preprocessing module to obtain the daily timing error and timeout. The time synchronization module outputs broadcast time synchronization commands that conform to the DLT645-2007 State Grid multi-function energy meter communication protocol, including infrared mode and RS485 mode.

6. The on-site detection system for the clock of the energy meter and metering terminal as described in claim 5, characterized in that: The signal preprocessing module includes an antenna interface and a BeiDou & GPS timing unit, and an energy meter optocoupler input shaping and input protection unit. The antenna interface and BeiDou & GPS timing unit obtains standard time through GPS and BeiDou satellite synchronization, and performs time synchronization and clock verification functions for the energy meter. The energy meter optocoupler input shaping and input protection unit receives the second pulse input from four energy meters. The second pulse output from the energy meter is an unconventional electrical signal, which is then converted into an electrical signal for measurement. In case of wiring errors or misconnection of voltage lines, the module protects the equipment and personnel from damage. The daily timing error / overtime measurement module includes a high-precision temperature-compensated crystal oscillator unit that uses a high-stability, high-frequency standard pulse signal to send to the MCU and the second pulse signal of the energy meter for calculation and processing to determine the daily timing error and overtime days of the energy meter. The time synchronization module includes a central processing unit and a data processing unit, an interaction unit, a display unit, an output unit, and a power management unit. The central processing unit and the data processing unit use a 32-bit high-frequency processor to analyze data and perform inter-module communication. The interaction unit is the device's input interface, allowing users to select test parameters via a touchscreen. The display unit displays the device's test modes and measurement results, enabling human-machine interaction. The output unit outputs 10MHz, 1MHz, 1kHz, and 1Hz signals. The power management unit serves as the device's power unit, providing power to the device.

7. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the on-site detection method for the electricity meter and metering terminal clock as described in any one of claims 1 to 4.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the on-site detection method for the electricity meter and metering terminal clock as described in any one of claims 1 to 4.

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