Method for determining impedance in front of meter based on time synchronization

Abstract

The invention discloses a pre-meter impedance determination method based on time synchronization, a meter box terminal is utilized, the meter box terminal comprises a high-level core and a basic core, and the method comprises the following steps: counting the RTC time difference of the high-level core and the basic core once every T0 time, and counting the system task time and the RTC time difference of the high-level core once, correcting user electricity meter time by using the first time difference and the second time difference; the high-level chip calculates voltage data of the meter box every T1 time and marks a time mark to obtain a meter box cache queue; the advanced core receives the user electric meter data pushed by the basic core once every T2 time and screens out the electric meter box voltage with the minimum time difference corresponding to the electric meter box for impedance calculation to obtain an impedance data set; and the high-level core performs filter point processing and mean value processing on the impedance data set to obtain impedance data. According to the method for determining the impedance in front of the meter based on time synchronization, the accuracy of the impedance in front of the meter can be effectively improved, and it is convenient to check which meter has line abnormity.

Description

Technical Field

[0001] This invention belongs to the field of low-voltage distribution area meter box line loss technology, and relates to a method for determining the meter front impedance based on time synchronization. Background Technology

[0002] With industrial development and the increasing electricity consumption of residents, energy conservation and regulation have become particularly important. The power loss in residential meter boxes is also becoming increasingly serious. Current conventional methods only detect the power loss in the meter box without specifying the cause, and the complex wiring inside the meter box makes troubleshooting difficult. Especially with the widespread adoption of app-based solutions for meter boxes, some manufacturers use different CPUs for the data acquisition and calculation modules, which can lead to low accuracy or abnormalities in the calculated impedance before the meter.

[0003] Therefore, a new time-synchronized method for determining the front impedance of the meter is needed to solve the above problems. Summary of the Invention

[0004] The purpose of this invention is to provide a time-synchronized method for determining the front impedance of a meter, in order to solve the problems of the prior art.

[0005] The technical solution of the present invention is as follows:

[0006] A method for determining the front impedance of a meter based on time synchronization, utilizing a meter box terminal comprising an advanced core and a basic core, includes the following steps:

[0007] Step 1: Calculate the first time difference between the RTC time of the advanced core and the RTC time of the basic core every T0 time, and calculate the second time difference between the system task time of the advanced core and the RTC time. Use the first time difference and the second time difference to correct the user's electricity meter time. The corrected user's electricity meter time corresponds to the system task time of the advanced core.

[0008] Step 2: The advanced core calculates the meter box voltage data every T1 time and adds a timestamp to obtain the meter box cache queue, and adds it to the data cache queue;

[0009] Step 3: The advanced core receives user meter data pushed by the basic core every T2 time and filters out the meter box voltage with the smallest time difference for impedance calculation to obtain an impedance data set, and adds the calculation results to the data cache queue.

[0010] Step 4: The advanced core performs filtering and averaging on the impedance data set obtained in Step 3 to obtain impedance data.

[0011] Furthermore, the filtering process in step 5 includes extreme value removal from the impedance dataset, rate of change stability filtering, and statistical consistency filtering.

[0012] Furthermore, the extreme value rejection of the impedance data set is to judge each impedance data by the following formula:

[0013] R min ≤R i ≤R max

[0014] In the formula, R i is the impedance value meeting the conditions, R min is the minimum value in the impedance data set, and R max is the maximum value in the impedance data set.

[0015] Furthermore, the change rate stability filtering is to judge each impedance data by the following formula:

[0016] ∣R i -R i-1 ∣≤α×R i-1

[0017] When α ≤ 50%, then R i is the impedance value meeting the conditions.

[0018] Furthermore, the statistical consistency filtering is to judge each impedance data by the following formula:

[0019] μ - βσ ≤ R i ≤ μ + βσ

[0020] In the formula, R i is the impedance value meeting the conditions, μ is the mean value of the impedance data set, σ is the standard deviation of the impedance data set, and β is a constant.

[0021] Furthermore, in step 3, the specific operation of screening the cabinet voltage with the smallest time difference for impedance calculation is as follows: the advanced core filters the cabinet voltage data with the smallest error from the user's meter according to the phase where the user's meter is located, and cyclically selects the smallest time difference from the cabinet cache queue. When the minimum time difference t_min < t_set, the user's meter and the cabinet meet the calculation data, and a qualified data queue is obtained for impedance calculation. Among them, t_min = t_mter_afger - t_box, t_mter_afger = t_1 + t_meter - t_4, t_mter_afger is the corrected user meter time, t_1 is the time difference between the RTC time of the advanced core and the RTC time of the basic core, t_meter is the user meter acquisition time, t_4 is the time difference between the RTC time of the advanced core and the system task time, t_box is the cabinet time, and t_set is the threshold.

[0022] Furthermore, the impedance calculation in step 3 is specifically as follows:

[0023]

[0024] In the formula, θ1 is the phase angle of the meter box voltage, θ2 is the phase angle of the user voltage, θ3 is the phase angle of the user current, U1 is the meter box voltage value, U2 is the user meter voltage value, I is the user meter current value, and θ1 is the phase angle of the meter box voltage.

[0025] Furthermore, step 3 of the impedance calculation also includes a confidence level assessment. A confidence level greater than or equal to 0.85 is considered a qualified impedance value, which is then added to the qualified impedance queue data. The confidence level is calculated using the following formula:

[0026] Confidence = 1 - (σ_R / R_avg)

[0027] In the formula, Confidence is the confidence level, σ_R is the standard deviation of the calculated impedance value, and R_avg is the average impedance value.

[0028] Furthermore, T0 is 1 second, T1 is 20ms, T2 is 1 minute, and T3 is 20ms.

[0029] Beneficial effects: The time-synchronized method for determining the front impedance of the meter in this invention can effectively improve the accuracy of the front impedance and facilitate the identification of which meter has a circuit abnormality. Attached Figure Description

[0030] Figure 1 This is a data flow diagram of the time-synchronized front impedance determination method of the present invention;

[0031] Figure 2 The flowchart shows the method for determining the front impedance based on time synchronization.

[0032] Figure 3 This is a diagram showing the correspondence between basic core minute data, advanced core data queues, meter box data, and user meter data. Detailed Implementation

[0033] Please see Figures 1-3 As shown, the time-synchronization-based method for determining the front impedance of a meter, utilizing the basic and advanced cores within the meter box terminal, includes the following steps:

[0034] Step 1: Set the calculation mode. The fast calculation mode outputs results every 15 minutes, and the slow calculation mode outputs results once a day.

[0035] Step 2: The advanced chip actively acquires the base chip's time upon power-up, achieving time synchronization between the advanced chip and the base chip;

[0036] Step 3: Statistically calculate the time difference between the RTC time of the advanced core and the basic core once per second, and statistically calculate the time difference between the system time (SPI task time) of the advanced core and the RTC time of the advanced core once per second. Calculate these two time differences to correct the meter time, and after correction, it corresponds to the system time of the advanced core.

[0037] t_1 = th_2 - tb_3;

[0038] t_4 = th_2 - t_5;

[0039] In the formula, t_2 is the RTC time of the advanced core, t_3 is the RTC time of the basic core, and t_5 is the system task time of the advanced core;

[0040] Step 3: The advanced core calculates the voltage data of the meter box in real time every 20 ms and marks the time stamp, and adds it to the data cache queue;

[0041] Step 4: Receive the minute data (voltage and current) of the user's meter pushed by the basic unit, and correct the user's meter data to the system task time of the advanced core.

[0042] t_mter_afger = t_1 + t_meter - t_4;

[0043] t_mter is the acquisition time of the user's meter;

[0044] t_1: The time difference between the RTC time of the advanced core and the basic core:

[0045] t4: The time difference between the RTC time of the advanced core and the system task time;

[0046] t_mter_afger: The time of the meter after correction.

[0047] Step 5: The advanced core filters the voltage data of the meter box with the smallest error from the user's minute according to the phase where the user is located, and cyclically selects the smallest time difference from the meter box cache queue, and the threshold is 20 ms;

[0048] t_min = t_mter_afger - t_box;

[0049] t_min is the time difference between the meter and the meter box;

[0050] t_set is the difference threshold, and t_set is 20 ms. When t_min < t_set, the meter and the meter box meet the calculation data and are added to the data queue cache to wait for calculation.

[0051] Step 6: Obtain the meter and meter box data from the qualified data queue for impedance calculation;

[0052]

[0053] In the formula, θ1 is the phase angle of the meter box voltage, θ2 is the phase angle of the user voltage, θ3 is the phase angle of the user current, U1 is the meter box voltage value, U2 is the user meter voltage value, and I is the user meter current value.

[0054] (2) Confidence assessment:

[0055] Confidence = 1 - (σ_R / R_avg)

[0056] Where: Confidence: confidence level (0-1), σ_R: standard deviation of the calculated impedance (Ω), R_avg: average impedance (Ω).

[0057] A confidence level of 0.85 or higher is considered a valid impedance value and is added to the valid impedance queue.

[0058] Step 7: Filter and average the output impedance results;

[0059] 1) Remove extreme values ​​from the impedance data set, first round of filtering.

[0060] R min ≤R i ≤R max

[0061] In the formula, R m in represents the minimum value in the impedance set, R max This represents the maximum value in the dataset;

[0062] 2) Rate of change stability filtering, second round of filtering

[0063] |R i -R i-1 |≤α×R i-1

[0064] a) Identify abrupt changes caused by data asynchrony or momentary interference;

[0065] b) α allows for a relative rate of change of 50%; anything exceeding this threshold is considered abnormal.

[0066] 3) Based on the above two filters, finally perform statistical consistency filtering:

[0067] μ-βσ≤R i ≤μ+βσ

[0068] illustrate:

[0069] Identify the most concentrated core clusters from the stable impedance data;

[0070] μ: Mean of impedance dataset; σ: Standard deviation of impedance dataset;

[0071] β = 2.0: Contains approximately 95% of normally distributed data (2σ principle);

[0072] Ri is the impedance value that is satisfied.

[0073] Step 8: Output impedance results;

[0074] Example: Taking a 300 milliohm impedance as an example, by comparing the two methods, the time synchronization method greatly improves the accuracy of impedance calculation.

[0075] 1) Standard Calculation Method: Calculation without time stamp, using real-time single-phase voltage from the meter box. This method suffers from voltage lag compared to user voltage changes. As shown in Table 1, the calculated impedance error is relatively large.

[0076] Table 1 shows the impedance calculation table without time scale.

[0077] User load change (V) User current (A) Real-time meter box corresponding phase voltage during calculation Impedance before meter (mΩ) 220.12 5.10 220.50 74.50 221.60 4.33 222.45 196.30

[0078] 2) Using the time synchronization method: Table 2 shows the voltage change data of one phase of the corresponding meter box when the user load changes, and the calculated impedance results are shown in Table 2.

[0079] Table 2. Voltage Changes of One Phase in the Box When User Load Changes

[0080] time User voltage (V) User current (A) Meter box voltage (V) Impedance (milliohms) 2025-10-0919：35：20 220.12 5.10 221.60 290.19 2025-10-0919：35：21 221.60 4.33 222.84 286.37 2025-10-0919：35：23 220.90 4.86 222.45 320.65

[0081] This invention can effectively improve the accuracy of the meter's impedance, facilitating the identification of specific meters with wiring abnormalities. It is highly adaptable; as long as the data interface is agreed upon with the data push module, it can be matched with various manufacturers. The invention is configurable, offering both a rapid calculation mode during peak electricity consumption periods and a slow calculation mode during off-peak periods.

Claims

1. A method for determining the pre-meter impedance based on time synchronization, characterized in that, Using a meter box terminal, the meter box terminal includes a high - level core and a basic core, and the method includes the following steps: Step 1: Statistically calculate the first time difference between the RTC time of the high - level core and the RTC time of the basic core every T0 time, and statistically calculate the second time difference between the system task time and the RTC time of the high - level core. Use the first time difference and the second time difference to correct the user meter time, and the corrected user meter time corresponds to the system task time of the high - level core; Step 2: The high - level core calculates the meter box voltage data and marks the time every T1 time, obtains a meter box cache queue, and adds it to the data cache queue; Step 3: The high - level core receives the user meter data pushed by the basic core every T2 time and filters out the meter box voltage with the smallest time difference corresponding to the meter box time for impedance calculation, obtains an impedance data set, and adds the calculation result to the data cache queue; Step 4: The high - level core performs filtering point processing and mean value processing on the impedance data set obtained in Step 3 to obtain impedance data.

2. The method for determining the pre-meter impedance based on time synchronization as described in claim 1, characterized in that, The filtering point processing in Step 5 includes extreme value removal of the impedance data set, change rate stability filtering, and statistical consistency filtering.

3. The method for determining the pre-meter impedance based on time synchronization as described in claim 3, characterized in that, The extreme value removal of the impedance data set is to judge each impedance data using the following formula: R min ≤R i ≤R max In the formula, R i To satisfy the impedance value, R min R is the minimum value in the impedance data set. max This represents the maximum value in the impedance data set.

4. The method for determining the pre-meter impedance based on time synchronization as described in claim 3, characterized in that, The change rate stability filtering is to judge each impedance data using the following formula: ∣R i -R i-1 ∣≤α×R i-1 When α ≤ 50%, then R i The impedance value required to satisfy the conditions.

5. The method for determining the pre-meter impedance based on time synchronization as described in claim 3, characterized in that, The statistical consistency filtering is to judge each impedance data using the following formula: μ-βσ≤R i ≤μ+βσ In the formula, R i The impedance value that satisfies the conditions is μ, where μ is the mean of the impedance dataset, σ is the standard deviation of the impedance dataset, and β is a constant.

6. The method for determining the front impedance of a meter based on time synchronization as described in claim 1, characterized in that, Specifically, in Step 3, filtering out the meter box voltage with the smallest time difference corresponding to the meter box time for impedance calculation: The high - level core screens the meter box voltage data with the smallest error from the user meter according to the phase where the user meter is located, and cyclically selects the smallest time difference from the meter box cache queue. When the smallest time difference t_min < t_set, the user meter and the meter box meet the calculation data, and a qualified data queue is obtained for impedance calculation. Among them, t_min = t_mter_afger - t_box, t_mter_afger = t_1 + t_meter - t_4, t_mter_afger is the corrected user meter time, t_1 is the time difference between the RTC time of the high - level core and the RTC time of the basic core, t_meter is the user meter acquisition time, t_4 is the time difference between the RTC time of the high - level core and the system task time, t_box is the meter box time, and t_set is the threshold.

7. The method for determining the front impedance of a meter based on time synchronization as described in claim 1, characterized in that, Specifically, the impedance calculation in Step 3 is: In the formula, θ1 is the meter box voltage phase angle, θ2 is the user voltage phase angle, θ3 is the user current phase angle, U1 is the meter box voltage value, U2 is the user meter voltage value, and I is the user meter current value.

8. The method for determining the pre-meter impedance based on time synchronization as described in claim 1, characterized in that, The impedance calculation in Step 3 also includes confidence evaluation. When the confidence is greater than or equal to 0.85, it is a qualified impedance value, and the qualified impedance value is added to the qualified impedance queue data. The confidence is calculated by the following formula: Confidence = 1-(σ_R / R_avg) In the formula, Confidence is the confidence, σ_R is the standard deviation of the impedance calculation value, and R_avg is the average impedance.

9. The method for determining the front impedance of a meter based on time synchronization as described in claim 1, characterized in that, T0 time is 1 second, T1 is 20 ms, T2 is 1 minute, and T3 is 20 ms.

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