A method for preventing electricity theft from electricity meters

Abstract

This invention provides a method for preventing electricity theft using electricity meters, addressing the current challenges of detecting and obtaining evidence of electricity theft, as well as the issues of high reliability and susceptibility to misjudgments during detection. The method includes: collecting continuous voltage samples, performing second-order difference operations, and plotting a point distribution map to obtain empirical values, including the number of voltage waveform samples, a second-order difference threshold for the voltage waveform, and a threshold for the number of voltage samples exceeding this threshold. Continuous second-order voltage samples are randomly selected from the voltage samples for difference operations, compared with the second-order difference threshold, and a counter value is set. The voltage samples are then processed again, and the counter value is compared with the threshold value to determine the electricity theft status. By obtaining relevant empirical values, performing second-order difference operations on the voltage samples, and comparing the results with the empirical values ​​multiple times, the false positive rate of electricity theft status is reduced, and random errors are avoided. This method offers advantages such as high accuracy and strong reliability.

Description

Technical Field

[0001] This invention relates to the field of electricity meter anti-theft technology, and in particular to a method for preventing electricity theft in electricity meters. Background Technology

[0002] Electricity is an important resource related to the national economy and people's livelihood, and it is inseparable from people's production and life. With the rapid development of the national economy, people's production and life have increasingly increased their demand for electricity resources, which has become an indispensable part of social and economic development.

[0003] With technological advancements, methods of electricity theft have become increasingly sophisticated, such as short-circuiting phase wires and diverting live wire current. Currently, one existing anti-theft technology in electricity theft and non-compliance management involves using a dimmer. A dimmer works by decreasing or increasing the RMS voltage value to cause a light source of a certain average power to produce different light intensities. Dimmer anti-theft involves connecting a dimmer device in series between the L or N line. When rotating the dimmer device, the meter's error must be within 1%. Currently, there are two main implementation schemes: apparent power metering and constant metering. Apparent power metering means that when an external interference signal is detected on the voltage, the meter switches to measuring electricity consumption using apparent power. The constant metering scheme, on the other hand, switches to measuring electricity consumption using constant power after detecting the connection of a dimmer.

[0004] The invention disclosed in Chinese patent literature, "A Method for Detecting Electricity Theft Based on Second-Order Differential Values ​​of Voltage Waveforms," ​​with publication number CN110261674A, provides a method for detecting dimmer electricity theft in electronic electricity meters. By performing second-order differential operations on multiple voltage sampling points, it provides a more reliable detection method for dimmer electricity theft, improving the anti-theft function of the electricity meter. However, because certain specific sinusoidal voltage values ​​contain a large DC component, these signals are easily misjudged as dimmer electricity theft. In addition, this invention does not perform multiple comparisons based on empirical values ​​obtained through analysis and processing of sampled values ​​to determine the actual electricity theft status. Therefore, the reliability of electricity theft detection still needs to be improved. Summary of the Invention

[0005] This invention aims to solve the problems of the difficulty in detecting and obtaining evidence of electricity theft, and the low reliability of detection due to the susceptibility to misjudgments during the detection process.

[0006] The above technical problems are solved by the following technical solution: a method for preventing electricity theft in electricity meters, comprising: S1. Adjust the DIMMER setting on the dimmer switch and collect several consecutive voltage sample values; S2. After performing second-order difference operations on several consecutive voltage sample values, draw the corresponding point distribution map and obtain several empirical values. These empirical values ​​include the number of voltage waveform samples, the second-order difference threshold of the voltage waveform, and the threshold for the number of voltage sample values ​​that are greater than the second-order difference threshold of the voltage waveform. S3. Randomly select several consecutive secondary voltage sampling values ​​from several consecutive voltage sampling values ​​and perform differential operation processing; S4. Set the counter count value according to the relationship between the differential operation processing result and the voltage waveform secondary differential threshold. S5. Reprocess several voltage sample values ​​and determine the electricity theft status based on the relationship between the counter count value and the number of voltage sample values ​​that are greater than the second differential threshold of the voltage waveform.

[0007] By adjusting the various settings of the DIMMER dimmer, voltage sampling of the output voltage waveform is achieved. The continuous voltage sample values ​​are then subjected to second-order difference operations, and the distribution of the operation results is plotted in an Excel spreadsheet. Three relevant empirical values ​​are derived: the number of voltage waveform samples, the second-order difference threshold for the voltage waveform, and the threshold for the number of voltage sample values ​​exceeding the second-order difference threshold, thus completing the preparatory process for the DIMMER algorithm. For a large number of voltage sample values, three consecutive second-order voltage sample values ​​are randomly selected and sequentially subjected to first-order and second-order difference operations, with the absolute value of the results taken. The difference operation results are compared with the second-order difference threshold of the voltage waveform to update the counter value. The voltage sample values ​​are then reprocessed, and the DIMMER electricity theft status is determined based on the relationship between the counter value and the aforementioned threshold.

[0008] Preferably, in step S5, determining the electricity theft status includes: when the counter count value is greater than or equal to the threshold number, it is determined that the device has entered the DIMMER electricity theft preparation state, and the number of times it has entered the DIMMER electricity theft preparation state is counted; when the counter count value is less than the threshold number, the counter count value remains unchanged, and it is determined that the device has entered the non-DIMMER electricity theft state. When the counter count value is greater than or equal to the threshold number, because certain specific sinusoidal voltage values ​​contain a large DC component, these signals are easily misjudged as dimmer electricity theft. At the same time, the existence of accidental events during the detection process may also lead to misjudgment of the electricity theft status. Therefore, further status determination is required based on this. So, the status determined at this time is the DIMMER electricity theft preparation state. Setting the DIMMER electricity theft preparation state can improve the accuracy and reliability of the electricity theft detection process.

[0009] Preferably, in step S5, if the number of times the device enters the DIMMER electricity theft preparation state exceeds a preset number, it is determined that the device has entered the DIMMER electricity theft state; if the number of times the device enters the DIMMER electricity theft preparation state does not exceed the preset number, it is determined that the device has entered the non-DIMMER electricity theft state. Determining the electricity theft state based on whether the number of times the device enters the DIMMER electricity theft preparation state exceeds the preset number makes the misjudgment of the electricity theft state a low-probability event.

[0010] Preferably, in step S3, the differential operation processing includes performing first-order and second-order differential operations sequentially on three randomly selected consecutive secondary voltage sample values, and taking the absolute value of the second-order differential operation result. By performing second-order differential operations on multiple voltage sample values, a more reliable detection method for Dimmer electricity theft is provided, improving the meter's anti-theft function. Taking the absolute value of the second-order differential operation result facilitates subsequent comparison and judgment.

[0011] Preferably, in step S4, the data reprocessing includes continuously processing a number of voltage sample values ​​in a slip manner, where the number of voltage sample values ​​is the same as the number of voltage waveform samples. The purpose of slip is to reduce irregular fluctuations between voltage sample values, making the waveform curve smoother and improving the accuracy of the detection process.

[0012] Preferably, in step S4, the counter count value is set such that when the differential operation result is greater than or equal to the second differential threshold of the voltage waveform, the counter count value is incremented by one; when the differential operation result is less than the second differential threshold of the voltage waveform, the counter count value remains unchanged. By updating the counter's status value and performing multiple comparisons on intermediate results, the determination of the DIMMER's electricity theft status is more accurate, improving the reliability of electricity theft detection.

[0013] Preferably, in step S1, several voltage sampling values ​​are acquired by adjusting the dimmer at several levels, with each level triggering a DMA interrupt via an interrupt service routine. Each level of the dimmer corresponds to a DMA interrupt in the interrupt service routine. By executing the corresponding DMA interrupt routine, waveform data is sampled, thereby obtaining a large number of continuous voltage sampling values ​​for analysis and processing during the actual detection process.

[0014] Preferably, in step S2, the voltage waveform secondary difference threshold is the product of the voltage sample value with the largest absolute value among several consecutive voltage sample values ​​and a random number, wherein the random number ranges from 0.01 to 0.99. Setting the voltage waveform secondary difference threshold facilitates comparison and judgment, thereby promptly identifying abnormal sampled voltage values ​​for further detection and understanding of the actual electricity theft status.

[0015] The beneficial effects of this invention are as follows: by analyzing and processing the voltage sample values, reliable relevant empirical values ​​are obtained; by performing secondary differential processing on the voltage sample values ​​and combining it with the slip method, an intermediate judgment state for the DIMMER electricity theft preparatory state is set; the calculation results are compared with empirical values ​​multiple times, thereby obtaining a judgment result with high accuracy. This reduces the misjudgment rate of the actual electricity theft state caused by some voltages containing large DC components, and also avoids random errors in the detection process, thereby improving the accuracy and reliability of electricity theft detection. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the detection process of the present invention. Detailed Implementation

[0017] Example 1: This example provides a method for preventing electricity theft using an electricity meter. The specific process is as follows: Figure 1 As shown, the process includes: S101, adjusting the dimmer setting to collect N consecutive voltage sample values; S102, performing second-order difference operations on the N consecutive voltage sample values ​​and plotting the corresponding point distribution map, obtaining three empirical values: the number of voltage waveform samples (COUNTS), the second-order difference threshold (THR1) of the voltage waveform, and the threshold (THR2) for the number of voltage sample values ​​greater than THR1; S103, randomly selecting three consecutive second-order voltage sample values ​​X1, X2, and X3 from the N consecutive voltage sample values ​​to perform first-order difference operations: Y1 = X2 - X1; Y2 = X3 - X2, and second-order difference operations: Z = Y2 - Y1, taking the absolute value of Z. S104. Is |Z| greater than THR1? S105. Increment the counter Zcount by 1 to Zcount1. S106. Keep the counter Zcount unchanged. S107. Reprocess the consecutive COUNTS voltage samples in the form of slip, and similarly update the counter value to ZcountM. S108. Is ZcountM greater than THR2? S109. Determine whether to enter the DIMMER power theft preparation state and count the number K. S110. Determine whether to enter the non-DIMMER power theft state. S111. Does K exceed the preset number? S112. Determine whether to enter the DIMMER power theft state.

[0018] In S101, the dimmer has 12 settings, each corresponding to a DMA interrupt in the interrupt service routine. Adjusting each setting triggers the corresponding DMA interrupt routine to collect 512 consecutive voltage sample values. In S102, after collecting a sufficient number (which can be set to N) of consecutive voltage sample values, these voltage sample values ​​are subjected to second-order difference operations. Using a spreadsheet tool such as Excel, a point distribution diagram corresponding to the second difference of the N voltage sample values ​​is plotted. Three empirical values ​​are derived from the analysis: the number of voltage waveform samples (COUNTS), the voltage waveform second-order difference threshold (THR1), and the threshold (THR2) for the number of voltage sample values ​​greater than THR1. The voltage waveform second-order difference threshold (THR1) is the product of the voltage sample value with the largest absolute value among several consecutive voltage sample values ​​and a random number, with the random number ranging from 0.01 to 0.99. In S103, three consecutive secondary voltage sampling values ​​X1, X2, and X3 are randomly selected from N consecutive voltage sampling values ​​and subjected to first-order difference operations in sequence: Y1 = X2 - X1; Y2 = X3 - X2. Then, second-order difference operations are performed: Z = Y2 - Y1, and the absolute value of Z, |Z|, is taken. In S104 to S106, after the counter is reset, the counter values ​​are set according to the relationship between the absolute value of the secondary difference operation result |Z| and the voltage waveform secondary difference threshold THR1 (S104) for subsequent comparison. When the absolute value of the secondary difference operation result |Z| is greater than the voltage waveform secondary difference threshold THR1, the counter is incremented by 1 (S105); when the absolute value of the secondary difference operation result |Z| is less than the voltage waveform secondary difference threshold THR1, the counter remains unchanged (S106). In S107, following the aforementioned steps, the consecutive COUNTS voltage sample values ​​are reprocessed using a slip-out method, meaning the number of voltage sample values ​​is the same as the number of voltage waveform samples, and the counter value is updated to ZcountM. In S108 to S110, the actual electricity theft state is determined based on the relationship between the current counter value ZcountM and the number threshold THR2 (S108). When the counter value ZcountM is greater than the number threshold THR2, it is determined that the user has entered the DIMMER electricity theft preparation state, and the number of times the user has entered the DIMMER electricity theft preparation state is recorded (S109) to facilitate further determination of whether the user has entered the formal DIMMER electricity theft state; when the counter value ZcountM is less than the number threshold THR2, it is determined that the user has entered the non-DIMMER electricity theft state (S110).In S111 to S112, the system pre-sets an upper limit on the number of times it can enter the DIMMER power theft preparation state, which is generally set to 3 times. If the actual number of times the DIMMER power theft preparation state is entered exceeds the preset number, it is determined that the system has entered the DIMMER power theft state (S112); if the actual number of times the DIMMER power theft preparation state is entered does not exceed the preset number, it is determined that the system has entered the non-DIMMER power theft state (S110).

[0019] Example 2: Since some signals contain a large DC component, such as voltage values ​​of 72V, 120V, etc., and sinusoidal signals containing the fifth harmonic, they are easily misjudged as dimmer electricity theft. Therefore, the present invention adopts the following technical means: continuously calculate the second-order difference value, and calculate the second-order difference maximum value DDMAX in sequence within 5 power frequency cycles (within 400 sampling points); determine the number of times DDMAX is abnormal (greater than a certain threshold) within 5 power frequency cycles.

[0020] Analysis of the collected sample data shows that if DDMAX exceeds 50000, it is determined that the system has entered a DIMMER (disruptive voltage theft) state; if DDMAX does not exceed 15000, it indicates a 240V, 120V, 72V, or 5th harmonic signal. Considering that different voltage sampling resistors in metering applications can cause proportional amplification or reduction of the overall voltage ADC value, the absolute threshold of the ADC can be changed to a value of k, where k = DDMAX / Vmax, DDMAX is the second-order differential maximum value, and Vmax is the voltage peak value. The threshold k is set to 0.03. This can be directly read from the register. Practical analysis shows that if the system has entered a DIMMER state, the number of times DDMAX exceeds the threshold within five power frequency cycles should be more than 10. If the system has not entered a DIMMER state (i.e., the voltage sampling value is a 5th harmonic, 120V, 72V, etc.), the number of times DDMAX exceeds the threshold within five power frequency cycles should be 0.

Claims

1. A method for preventing electricity theft in an electricity meter, characterized in that, include: S1. Adjust the DIMMER setting on the dimmer switch and collect several consecutive voltage sample values; S2. After performing second-order difference operations on several consecutive voltage sample values, draw the corresponding point distribution map and obtain several empirical values. These empirical values ​​include the number of voltage waveform samples, the second-order difference threshold of the voltage waveform, and the threshold for the number of voltage sample values ​​that are greater than the second-order difference threshold of the voltage waveform. S3. Randomly select several consecutive secondary voltage sampling values ​​from several consecutive voltage sampling values ​​and perform differential operation processing. S4. Set the counter value based on the relationship between the differential operation result and the second differential threshold of the voltage waveform; S5. Reprocess several voltage sample values, update the counter value, and determine the DIMMER electricity theft status based on the relationship between the counter value and the number of voltage sample values ​​that are greater than the second differential threshold of the voltage waveform. The data reprocessing includes continuously processing a number of voltage sample values ​​in a slip manner, the number of voltage sample values ​​being the same as the number of voltage waveform samples.

2. The method for preventing electricity theft from an electricity meter according to claim 1, characterized in that, In step S5, determining the electricity theft status includes determining that the electricity theft preparation state is entered when the counter count value is greater than or equal to the number threshold, and counting the number of times the electricity theft preparation state is entered. When the counter count value is less than the threshold number, the counter count value remains unchanged, and it is determined that the system has entered a non-DIMMER electricity theft state.

3. The method for preventing electricity theft in an electricity meter according to claim 2, characterized in that, In step S5, if the number of times the count enters the DIMMER electricity theft preparation state exceeds a preset number, it is determined that the state has entered the DIMMER electricity theft state; if the number of times the count enters the DIMMER electricity theft preparation state does not exceed the preset number, it is determined that the state has entered the non-DIMMER electricity theft state.

4. A method for preventing electricity theft from an electricity meter according to claim 1, characterized in that, In step S3, the differential operation processing includes performing first-order differential operation and second-order differential operation on three consecutive randomly selected voltage secondary sample values ​​in sequence, and taking the absolute value of the second-order differential operation result.

5. A method for preventing electricity theft in an electricity meter according to claim 1 or 4, characterized in that, In step S4, setting the counter count value includes incrementing the counter count value by one when the differential operation result is greater than or equal to the voltage waveform second differential threshold; and keeping the counter count value unchanged when the differential operation result is less than the voltage waveform second differential threshold.

6. A method for preventing electricity theft from an electricity meter according to claim 1 or 2, characterized in that, In step S1, the acquisition is performed by adjusting several levels of the dimmer, and each level is used to execute a DMA interrupt to acquire several consecutive voltage sample values ​​through an interrupt service routine.

7. A method for preventing electricity theft from an electricity meter according to claim 1 or 2, characterized in that, In step S2, the voltage waveform second-order differential threshold is the product of the voltage sample value with the largest absolute value among several consecutive voltage sample values ​​and a random number, wherein the random number ranges from 0.01 to 0.99.

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