Self-calibration method and system for measuring function of measuring switch

Abstract

The invention relates to the technical field of electric power measurement, in particular to a self-calibration method and system for measuring the metering function of a switch, and the method comprises the steps: a standard signal source carries out the current data point collection of a data collection time period at a fixed collection frequency, carries out the filtering processing of the collected data of the current data point, and obtains the current value of the data collection time period; determining a reference current signal required to be output by a standard signal source based on the acquired current value of the data acquisition time period; the metering module samples a reference current signal output by the standard signal source to obtain a metering sampling current; and carrying out error threshold comparison on the difference between the metering sampling current and the reference current signal, and carrying out self-calibration adjustment on the measurement switch based on a comparison result. Metering deviation is corrected in time, misoperation of overload protection and short-circuit protection is avoided, meanwhile, field calibration operation is simplified, and the self-calibration function can be completed without complex test equipment.

Description

Technical Field

[0001] The present invention relates to the technical field of electric power metering, and in particular to a self-calibration method and system for measuring metering function of a switch. Background Art

[0002] Measuring switches are widely used in power systems. They have the function of protecting circuits and equipment from damage such as overcurrent and short circuit. They can also monitor and record electrical parameters such as voltage, current, power factor, etc. in real time, thereby providing more sophisticated and intelligent electricity metering functions.

[0003] In the field of power metering, whole box metering is a key link, which refers to the precise measurement of power parameters directly in the substation or power metering box. These measurement data are used to settle electricity bills or analyze the operation of the power system. In this process, the metering sampling of the measuring switch needs to be very precise to ensure the accuracy and fairness of the measurement.

[0004] However, when these measurement data are transmitted to the on-site measuring switch through equipment such as mutual inductors, measurement sampling deviations often occur, resulting in low accuracy of overload protection and short-circuit protection of the measuring switch during use, which increases the risk factor; inaccurate measurement accuracy leads to high losses in the substation. At the same time, on-site verification operations are complicated, there is no suitable tooling to complete on-site self-verification identification, or super-complex test equipment is required to complete the self-verification function of the on-site measuring switch. Summary of the invention

[0005] In order to solve the above problems, the present invention provides a self-calibration method for the metering function of a measuring switch, which is applied to the measuring switch. The measuring switch includes a built-in standard signal source and a metering module. The standard signal source is used to generate a preset standard reference signal; the metering module is used to measure and collect the standard reference signal; the method includes:

[0006] S1. The standard signal source collects current data points in a data collection period at a fixed collection frequency, and performs filtering processing on the collected data of the current data points to obtain the current value of the data collection period;

[0007] S2. Determine the reference current signal required to be output by the standard signal source based on the current value obtained during the data acquisition period;

[0008] S3, the metering module samples the reference current signal output by the standard signal source to obtain a metering sampling current;

[0009] S4, the measurement sampling current is subtracted from the reference current signal to perform an error threshold comparison, and a self-calibration adjustment of the measurement switch is performed based on the comparison result. The specific method of the self-calibration adjustment is:

[0010] a. Initialize the calibration factor and the current number of iterations, and set the maximum number of calibration iterations and calibration tolerance;

[0011] b. Multiply the reference current signal by the calibration factor to obtain the calibration current value, subtract the measurement sampling current from the calibration current value and multiply by a fixed coefficient to obtain a new calibration factor;

[0012] c. Adjust the limit value of the new calibration factor. If the new calibration factor is less than the minimum limit value, set the new calibration factor equal to the minimum limit value; if the new calibration factor is greater than the maximum limit value, set the new calibration factor equal to the maximum limit value;

[0013] d. Recalculate and multiply the new calibration factor with the reference current signal to obtain a new calibration current value, and accumulate the current number of iterations;

[0014] e. Subtract the new calibration current value from the metering sampling current to determine whether the difference is less than or equal to the calibration tolerance. If so, the self-calibration adjustment is completed; if not, the new calibration current value is used as the calibration current value in step b, and step be is re-executed;

[0015] Step e also includes stopping the self-calibration adjustment and triggering a self-calibration adjustment failure signal when the current iteration number accumulates to the maximum calibration iteration number and the difference between the new calibration current value and the metering sampling current is greater than the calibration tolerance.

[0016] In order to improve the anti-interference performance of the current data point acquisition of the standard signal source, the current data point acquisition data is filtered in S1, and the specific method is as follows:

[0017] Set the window size of the median filter and select the current data point within the corresponding window size for a single current data point;

[0018] Sorting the selected current data points, and taking the median as the current value of the single current data point;

[0019] Traversing all current data points through a median filter to obtain a corresponding current value data array, and performing autocorrelation function calculation on the current value data array;

[0020] The autocorrelation function value calculated by the autocorrelation function is compared with the maximum lag time threshold. If it is greater than or equal to the maximum lag time threshold, it means that the current value data array of all current data points is not stable. Then the current data points are collected again in the current stable time period until the autocorrelation function value is less than the maximum lag time threshold to obtain the stable current value of all current data points.

[0021] In order to improve the accuracy of the output signal of the standard signal source, the data collection period is selected from the current stable time period.

[0022] In a specific implementation manner, the reference current signal required to be output by the standard signal source is determined in S2 based on the current value acquired during the data acquisition period, specifically in the following manner:

[0023] S2.1. Determine the range interval corresponding to the output current of the standard signal source according to the current value obtained during the data collection period;

[0024] S2.2, constructing a mapping relationship equation between the current value in the data collection period and the range of the output current;

[0025] S2.3. Substitute the current value during the data collection period into the constructed mapping relationship equation to obtain the output current value, and set the output current value as the reference current signal required to be output by the standard signal source.

[0026] The mapping relationship equation is as follows:

[0027]

[0028] In the formula, I in Indicates the current value; I out Indicates the output current value; I Amax with I Amin Respectively represent the maximum and minimum values ​​of the output current range; I Bmax with I Bmin Respectively represent the maximum and minimum values ​​of the input range.

[0029] In the S4, the measurement sampling current is subtracted from the reference current signal to perform an error threshold comparison. Specifically, the measurement sampling current is subtracted from the reference current signal to obtain an error value, which is compared with the error threshold. If the error value is less than the error threshold, the measurement switch self-calibration adjustment is not performed; if the error value is greater than or equal to the error threshold, the measurement switch self-calibration adjustment is performed.

[0030] Another aspect of the present invention provides a self-calibration system for measuring the metering function of a switch, comprising:

[0031] The collection and filtering module is used to collect current data points in a data collection period at a fixed collection frequency, and filter the collected data of the current data points to obtain the current value of the data collection period;

[0032] An output module, used to determine a reference current signal required to be output by a standard signal source based on the current value acquired during the data acquisition period;

[0033] A measurement sampling module is used to sample the reference current signal output by the standard signal source to obtain a measurement sampling current;

[0034] The self-calibration module is used to make a difference between the measurement sampling current and the reference current signal to compare the error threshold, and perform self-calibration adjustment of the measurement switch based on the comparison result.

[0035] The present invention also provides a self-calibration device for measuring the metering function of a measuring switch, comprising a processor and a memory, wherein the processor implements the self-calibration method for the metering function of the measuring switch as described above when executing program data stored in the memory.

[0036] Beneficial effects: The present invention is a self-calibration method and system for measuring the metering function of a measuring switch. By setting a standard signal source and a metering module, the standard signal source collects and filters the current data points, ensuring the accuracy and reliability of the reference current signal generated; the reference current signal is compared with the metering sampling signal of the metering module for error threshold and self-calibration adjustment, and the metering deviation is corrected in time to avoid the malfunction of overload protection and short-circuit protection, thereby reducing the risk factor. At the same time, the present invention simplifies the on-site verification operation, and the self-calibration function can be completed without complex test equipment. The current averaging method based on stationarity and time window is used for processing and self-calibration to achieve high-precision data metering verification in complex environments, and more stable and anti-interference metering calibration verification is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Flow chart of the self-calibration method for measuring the metering function of the switch. DETAILED DESCRIPTION

[0038] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings.

[0039] Example 1

[0040] This embodiment provides a self-calibration method for the metering function of a measuring switch, which is applied to the measuring switch, wherein the measuring switch includes a built-in standard signal source and a metering module, wherein the standard signal source is used to generate a preset standard reference signal; and the metering module is used to measure and collect the standard reference signal. The self-calibration method is specifically implemented in the following steps:

[0041] S1. The standard signal source collects current data points in a data collection period at a fixed collection frequency, and performs filtering processing on the collected data of the current data points to obtain the current value of the data collection period;

[0042] The data collection period in S1 is selected as the current stable period, that is, the period when the current is stable after the measuring switch is powered on, to avoid inaccurate self-calibration caused by current fluctuations. The standard signal source collects current data points in the current stable period by presetting the collection frequency, and filters the collected data of the current data points;

[0043] The filtering process of the current data point acquisition data is specifically performed as follows:

[0044] Set the window size of the median filter and select the current data point within the corresponding window size for a single current data point;

[0045] Sorting the selected current data points, and taking the median as the current value of the single current data point;

[0046] Traversing all current data points through a median filter to obtain a corresponding current value data array, and performing autocorrelation function calculation on the current value data array;

[0047] The autocorrelation function value calculated by the autocorrelation function is compared with the maximum lag time threshold. If it is greater than or equal to the maximum lag time threshold, it means that the current value data array of all current data points is not stable. Then the current data points are collected again in the current stable time period until the autocorrelation function value is less than the maximum lag time threshold to obtain the stable current value of all current data points.

[0048] The collected data of the current data points are filtered to obtain the stable current values ​​of all the current data points, and the average value of the stable current values ​​of all the current data points is calculated to obtain the current value in the current stable time period, which is the average current value of all the current data points.

[0049] S2. Based on the current value obtained during the data acquisition period, determine the reference current signal required to be output by the standard signal source, the specific method is as follows:

[0050] S2.1. Determine the range interval corresponding to the output current of the standard signal source according to the current value obtained during the data collection period;

[0051] S2.2, constructing a mapping relationship equation between the current value in the data collection period and the range of the output current;

[0052] The present application takes the current value of 1.5 mA in the data acquisition period as an example. The current value input range interval of the data acquisition period is 1-2 mA, and the corresponding range interval of the standard signal source output current is 4-20 mA.

[0053] According to the current value during the data collection period and the range of the output current, the mapping relationship equation between the two is constructed as follows:

[0054]

[0055] In the formula, I in Indicates the current value; I out Indicates the output current value; I Amax with I AminRespectively represent the maximum and minimum values ​​of the output current range; I Bmax with I Bmin Respectively represent the maximum and minimum values ​​of the input range.

[0056] S2.3. Substitute the current value during the data collection period into the constructed mapping relationship equation to obtain the output current value, and set the output current value as the reference current signal required to be output by the standard signal source.

[0057] S3, the metering module samples the reference current signal output by the standard signal source to obtain a metering sampling current;

[0058] S4. Subtract the measured sampling current from the reference current signal to perform an error threshold comparison, and perform a self-calibration adjustment of the measurement switch based on the comparison result.

[0059] In this embodiment, the reference current signal output by the standard data source is represented by N, and the metering sampling current sampled by the metering module is represented by P.

[0060] The error value is obtained by subtracting N from P and compared with the error threshold. If the error value is less than the error threshold, the self-calibration adjustment of the measurement switch is not performed, indicating that the metering function of the measurement switch is accurate; if the error value is greater than or equal to the error threshold, the self-calibration adjustment of the measurement switch is performed.

[0061] The specific method of the self-calibration adjustment of the measuring switch is as follows:

[0062] a. Initialize the calibration factor and the current number of iterations, and set the maximum number of calibration iterations and calibration tolerance;

[0063] In this embodiment, the calibration factor is set to 1, the current iteration number is set to 0, the maximum calibration iteration number is set to 10, and the calibration tolerance is set to 0.01;

[0064] b. Multiply the reference current signal N by the calibration factor to obtain the calibration current value, subtract the measurement sampling current P from the calibration current value and multiply by a fixed coefficient to obtain a new calibration factor;

[0065] c. Adjust the limit value of the new calibration factor. If the new calibration factor is less than the minimum limit value, set the new calibration factor equal to the minimum limit value; if the new calibration factor is greater than the maximum limit value, set the new calibration factor equal to the maximum limit value;

[0066] d. Recalculate and multiply the new calibration factor and the reference current signal N to obtain a new calibration current value, and accumulate the current number of iterations;

[0067] e. Subtract the new calibration current value from the measurement sampling current P to determine whether the difference is less than or equal to the calibration tolerance. If so, the self-calibration adjustment is completed, and the measurement switch is calibrated and adjusted using the new calibration factor; if not, the new calibration current value is used as the calibration current value in step b, and step be is re-executed;

[0068] At the same time, step e also includes stopping the self-calibration adjustment and triggering a self-calibration adjustment failure signal when the current iteration number accumulates to the maximum calibration iteration and the difference between the new calibration current value and the metering sampling current is greater than the calibration tolerance.

[0069] Example 2

[0070] This embodiment provides a self-calibration method for the metering function of a measurement switch, which implements self-calibration adjustment of the measurement switch by operating a standard signal source and a metering module, specifically including:

[0071] S1. The standard signal source collects current data points in a data collection period at a fixed collection frequency, and performs filtering processing on the collected data of the current data points to obtain the current value of the data collection period;

[0072] For each current data point, take the data points of the median filter window size around it, sort them and take the median as the value of the point, which can effectively reduce the impact of noise and outliers.

[0073]

[0074]

[0075]

[0076] S2. Determine the reference current signal required to be output by the standard signal source based on the current value obtained during the data acquisition period;

[0077]

[0078]

[0079] S3, the metering module samples the reference current signal output by the standard signal source to obtain a metering sampling current;

[0080] S4. Subtract the measured sampling current from the reference current signal to perform an error threshold comparison, and perform a self-calibration adjustment of the measurement switch based on the comparison result.

[0081]

[0082]

Claims

1. A self-calibration method for a measurement switch metering function, applied to a measurement switch, wherein the measurement switch comprises a built-in standard signal source and a metering module, wherein the standard signal source is used to generate a preset standard reference signal; The metering module is used to measure and collect standard reference signals, and is characterized in that: The method comprises: S1. The standard signal source collects current data points in a data collection period at a fixed collection frequency, and performs filtering processing on the collected data of the current data points to obtain the current value of the data collection period; S2. Determine the reference current signal required to be output by the standard signal source based on the current value obtained during the data acquisition period; S3, the metering module samples the reference current signal output by the standard signal source to obtain a metering sampling current; S4, the measurement sampling current is subtracted from the reference current signal to perform an error threshold comparison, and a self-calibration adjustment of the measurement switch is performed based on the comparison result. The specific method of the self-calibration adjustment is: a. Initialize the calibration factor and the current number of iterations, and set the maximum number of calibration iterations and calibration tolerance; b. Multiply the reference current signal by the calibration factor to obtain the calibration current value, subtract the measurement sampling current from the calibration current value and multiply by a fixed coefficient to obtain a new calibration factor; c. Adjust the limit value of the new calibration factor. If the new calibration factor is less than the minimum limit value, set the new calibration factor equal to the minimum limit value; if the new calibration factor is greater than the maximum limit value, set the new calibration factor equal to the maximum limit value; d. Recalculate and multiply the new calibration factor with the reference current signal to obtain a new calibration current value, and accumulate the current number of iterations; e. Subtract the new calibration current value from the metering sampling current to determine whether the difference is less than or equal to the calibration tolerance. If so, the self-calibration adjustment is completed; if not, the new calibration current value is used as the calibration current value in step b, and step be is re-executed; Step e also includes stopping the self-calibration adjustment and triggering a self-calibration adjustment failure signal when the current iteration number accumulates to the maximum calibration iteration number and the difference between the new calibration current value and the metering sampling current is greater than the calibration tolerance.

2. The self-calibration method for measuring the metering function of a measuring switch according to claim 1, characterized in that: In S1, the current data point collected data is filtered, and the specific method is as follows: Set the window size of the median filter, and select the current data point within the corresponding window size for a single current data point; Sorting the selected current data points, and taking the median as the current value of the single current data point; Traversing all current data points through a median filter to obtain a corresponding current value data array, and performing autocorrelation function calculation on the current value data array; The autocorrelation function value calculated by the autocorrelation function is compared with the maximum lag time threshold. If it is greater than or equal to the maximum lag time threshold, it means that the current value data array of all current data points is not stable. Then the current data points are collected again in the current stable time period until the autocorrelation function value is less than the maximum lag time threshold to obtain the stable current value of all current data points.

3. The self-calibration method for measuring the metering function of a measuring switch according to claim 1, characterized in that: In S2, based on the current value acquired during the data acquisition period, the reference current signal required to be output by the standard signal source is determined in the following manner: S2.

1. Determine the range interval corresponding to the output current of the standard signal source according to the current value obtained during the data collection period; S2.2, constructing a mapping relationship equation between the current value in the data collection period and the range of the output current; S2.

3. Substitute the current value during the data collection period into the constructed mapping relationship equation to obtain the output current value, and set the output current value as the reference current signal required to be output by the standard signal source.

4. The self-calibration method for measuring the metering function of a measuring switch according to claim 3, characterized in that: The mapping relationship equation is as follows: In the formula, I in Indicates the current value; I out Indicates the output current value; I Amax with I Amin Respectively represent the maximum and minimum values ​​of the output current range; I Bmax with I Bmin Respectively represent the maximum and minimum values ​​of the input range.

5. The self-calibration method for measuring the metering function of a measuring switch according to claim 1, characterized in that: In the S4, the measurement sampling current is subtracted from the reference current signal to perform an error threshold comparison. Specifically, the measurement sampling current is subtracted from the reference current signal to obtain an error value, which is compared with the error threshold. If the error value is less than the error threshold, the measurement switch self-calibration adjustment is not performed; if the error value is greater than or equal to the error threshold, the measurement switch self-calibration adjustment is performed.

6. The self-calibration method for measuring the metering function of a measuring switch according to claim 1, characterized in that: The data collection period is a current stable time period.

7. A self-calibration system for measuring the metering function of a switch, characterized in that: include: The collection and filtering module is used to collect current data points in a data collection period at a fixed collection frequency, and filter the collected data of the current data points to obtain the current value of the data collection period; An output module, used to determine a reference current signal required to be output by a standard signal source based on the current value acquired during the data acquisition period; A measurement sampling module is used to sample the reference current signal output by the standard signal source to obtain a measurement sampling current; The self-calibration module is used to make a difference between the measurement sampling current and the reference current signal to compare the error threshold, and perform self-calibration adjustment of the measurement switch based on the comparison result.

8. A self-calibration device for measuring the metering function of a switch, characterized in that: The method comprises a processor and a memory, wherein the processor implements the self-calibration method for the metering function of the measuring switch according to any one of claims 1 to 6 when executing the program data stored in the memory.

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