Thyristor speed control switch power theft detection method

Abstract

The invention discloses a method for detecting electricity theft of a thyristor speed regulating switch, comprising the following steps: designing a cyclic detection interval time according to a detection frequency of the thyristor speed regulating switch by an electric meter; setting an interval for ADC cycle acquisition to acquire periodic waveform data of a voltage, wherein the voltage waveform value is used for determining an electricity theft algorithm of the thyristor speed regulating switch; arranging the waveform data to obtain sampling midpoint data Ymin of the right half of a half-cycle of the waveform and peak data Ymax of the half-cycle waveform; calculating a slope K=(Ymax-Ymin) / Ymax according to a set electricity theft algorithm of the thyristor speed regulating switch; and comparing the K value with a preset K value of a normal waveform to determine if the K value is smaller than the normal waveform, determining that the thyristor speed regulating switch has entered an electricity theft state.

Description

Technical Field

[0001] The invention belongs to the technical field of electronic electric meters, and in particular relates to a method for detecting electricity theft of a thyristor speed regulating switch. Background Art

[0002] In the field of existing electronic electric meters, see Figure 1 There is a method of stealing electricity through a thyristor (SCR) speed control switch. The specific stealing principle is as follows: after the meter's sampled voltage passes through the thyristor speed control switch (dimmer), the measured effective value of the voltage and the phase angle between the voltage and current will undergo significant changes. If the meter uses a linear power supply, the measured RMS (Root Mean Square) voltage will decrease and the phase angle will increase. For a RC power supply, the RMS voltage will increase, and the phase angle will also increase. The final result is that the active power decreases and the reactive power increases. Since the meter charges based on active power, unscrupulous users can achieve their purpose of stealing electricity through the thyristor speed control switch.

[0003] Therefore, it is necessary to detect whether the electricity is being stolen by a thyristor speed control switch. In the existing technology, there are mainly the following methods for detecting thyristor speed control switches: (1) By performing FFT transformation on the voltage waveform and analyzing the harmonic content in the frequency domain to determine whether it is interfered with by the thyristor speed control switch, but this solution has high requirements for MCU performance and requires a lot of MCU resources, which is not practical for low-cost electricity meters. (2) By comparing the voltage waveform difference value with the abnormal value, this method judges by the difference between adjacent points, and it is easy to misjudge the normal waveform as the thyristor speed control switch state. Because the actual voltage waveform is not an ideal waveform, it is easy to make mistakes when there is a slight interference, such as harmonics. (3) Based on the maximum value of the voltage waveform and the inspection of the effective value, it is an empirical value summary and is prone to misjudgment. Summary of the Invention

[0004] In view of the above problems, the present invention provides a method for detecting electricity theft in a thyristor speed regulating switch. By comparing the waveform characteristics of the thyristor speed regulating switch, which are close to a square wave, with the ideal sinusoidal waveform, the state of the thyristor speed regulating switch is judged from the overall waveform. This method has the advantages of simple calculation and no misjudgment.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A method for detecting electricity theft in a thyristor speed regulating switch comprises the following steps:

[0007] Design the cycle detection interval time according to the detection frequency of the thyristor speed regulating switch by the electric meter;

[0008] Set the ADC cycle collection interval to collect voltage waveform data. The voltage waveform value is used to determine the power theft algorithm of the thyristor speed control switch.

[0009] Arrange the waveform data, make the negative half-wave data positive, and convert all of them into positive half-wave data, and obtain the sampling midpoint data Ymin of the right half of the waveform half cycle, and the half-cycle waveform vertex data Ymax;

[0010] According to the set thyristor speed control switch power stealing algorithm, calculate the slope K = (Ymax-Ymin) / Ymax;

[0011] The K value is compared with the preset normal waveform K value. If the K value is less than the normal waveform K value, it is determined that the thyristor speed control switch has entered the power stealing state.

[0012] Preferably, the K value of the normal sin waveform is obtained in advance as the basis for the judgment threshold. Then, the judgment is entered to obtain the K value of the real-time waveform data. If the K value is less than 15%, it is determined that the thyristor speed control switch has entered the power theft state.

[0013] Preferably, the ADC sampling uses the live wire as the reference ground, and the collected signal enters the ADC sampling terminal of the single-chip microcomputer through a resistor voltage divider.

[0014] Preferably, the ADC sampling frequency is greater than 3.2k, and 64 points of AC data are acquired.

[0015] Preferably, the model of the single chip processor is V8530.

[0016] The present invention has the following beneficial effects: the thyristor speed regulating switch is judged by the overall slope of the voltage waveform. The slope method is simple to calculate, faster than the FFT method, and saves MCU resources. Compared with the simple differential method, it can reduce the misjudgment caused by waveform distortion due to local interference. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic diagram of electricity theft through a thyristor speed regulating switch in the prior art;

[0018] Figure 2 Flowchart of the steps of the method for detecting electricity theft in a thyristor speed regulating switch according to an embodiment of the present invention;

[0019] Figure 3 Schematic diagram of the detection algorithm principle;

[0020] Figure 4 This is a normal 64-point waveform diagram;

[0021] Figure 5 This is a waveform diagram of a thyristor speed control switch (Dimmer);

[0022] Figure 6 It is a schematic diagram of the waveform with third harmonic;

[0023] Figure 7 Schematic diagram of an ADC sampling circuit in an embodiment of the present invention. DETAILED DESCRIPTION

[0024] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0025] See also Figure 2 , which is a flowchart of a method for detecting electricity theft in a thyristor speed regulating switch according to an embodiment of the present invention, includes the following steps:

[0026] Design the cycle detection interval time according to the detection frequency of the thyristor speed regulating switch by the electric meter; the detection interval time can be set to 5-10S;

[0027] Set the ADC sampling interval to collect voltage waveform data. The voltage waveform value is used to determine the power theft algorithm of the thyristor speed control switch. The ADC sampling frequency is greater than 3.2k, and 64 points of AC data are obtained.

[0028] Arrange the waveform data, make the negative half-wave data positive, and convert all of them into positive half-wave data, and obtain the sampling midpoint data Ymin of the right half of the waveform half cycle, and the half-cycle waveform vertex data Ymax;

[0029] According to the set thyristor speed control switch power stealing algorithm, calculate the slope K = (Ymax-Ymin) / Ymax;

[0030] The K value is compared with the preset normal waveform K value. If the K value is less than the normal waveform K value, it is judged that the thyristor speed control switch has entered the power theft state. Using the K value judgment can avoid misjudgment caused by harmonic interference.

[0031] In one embodiment of the present invention, the K value of the normal sin waveform is obtained in advance as the basis for the judgment threshold. Then, the judgment is entered to obtain the K value of the real-time waveform data. If the K value is less than 15%, it is determined that the thyristor speed control switch has entered the power theft state. Figure 3This is a normal sin waveform. For example, using the waveform typically sampled at 64 points in current electricity meters, the ideal sin waveform's K value is approximately 23% at the middle of the right half of the half-cycle. However, the waveform of a thyristor speed control switch gradually approaches a square wave as the speed control switch is adjusted, causing the K value to decrease, reaching a minimum of approximately 7%. In practice, 15% is set as the K value judgment criterion for the thyristor speed control switch, depending on the speed control amount.

[0032] Figures 4 to 6 , are three typical representatives of the measured 64-point waveform, namely the normal waveform, the thyristor speed control switch (Dimmer) waveform, and the case with third harmonic. The vertical axis is the ADC sampling amplitude, the full scale 1.1V represents 65536, and the horizontal axis is the number of sampling points. The K value of each waveform is calculated as follows:

[0033] Normal waveform K=(Ymax-Ymin) / Ymax=(3112-2369) / 3112=23.87%

[0034] Dimmer waveform K=(Ymax-Ymin) / Ymax = (3102-2873) / 3102=7.38%

[0035] Third harmonic K = (Ymax-Ymin) / Ymax = (3145-1885) / 3145 = 40.06%

[0036] From the results, we can see that by calculating the K value, it is easy to distinguish which state is normal metering, which state is normal metering with harmonics, and which state is dimmer electricity theft. Therefore, this algorithm provides a convenient and quick method for judging dimmer electricity theft in multi-function meters.

[0037] Furthermore, in one embodiment of the present invention, see Figure 7 ADC sampling uses the live wire as the reference ground, and the collected signal enters the ADC sampling terminal of the microcontroller processor through resistor voltage division. The model of the microcontroller processor is Wangao V8530.

[0038] Through the above-mentioned thyristor speed control switch power theft detection method, the thyristor speed control switch is judged by the overall slope of the voltage waveform. The slope method is simple to calculate, has the advantages of being faster than the FFT method and saving MCU resources, and has the advantage of reducing misjudgment caused by waveform distortion due to local interference compared to the simple differential method.

[0039] It should be understood that the exemplary embodiments described herein are illustrative and not restrictive. Although one or more embodiments of the present invention have been described in conjunction with the accompanying drawings, it should be understood by those skilled in the art that various changes in form and details may be made without departing from the spirit and scope of the present invention as defined by the appended claims.

Claims

1. A method for detecting electricity theft in a thyristor speed regulating switch, characterized in that: The following steps are involved: Design the cycle detection interval time according to the detection frequency of the thyristor speed regulating switch by the electric meter; Set the ADC cycle collection interval to collect voltage waveform data. The voltage waveform value is used to determine the power theft algorithm of the thyristor speed control switch. Arrange the waveform data, make the negative half-wave data positive, and convert all of them into positive half-wave data, and obtain the sampling midpoint data Ymin of the right half of the waveform half cycle, and the half-cycle waveform vertex data Ymax; According to the set thyristor speed control switch power stealing algorithm, calculate the slope K = (Ymax-Ymin) / Ymax; The K value is compared with the preset normal waveform K value. If the K value is less than the normal waveform K value, it is determined that the thyristor speed control switch has entered the power stealing state.

2. The method for detecting electricity theft in a thyristor speed regulating switch according to claim 1, wherein: The K value of the normal sin waveform is obtained in advance as the basis for the judgment threshold; then the judgment is entered to obtain the K value of the real-time waveform data. If the K value is less than 15%, it is determined that the thyristor speed control switch has entered the power theft state.

3. The method for detecting electricity theft in a thyristor speed regulating switch according to claim 1, wherein: ADC sampling uses the live wire as the reference ground, and the collected signal enters the ADC sampling end of the microcontroller processor through resistor voltage division.

4. The method for detecting electricity theft in a thyristor speed regulating switch according to claim 1, wherein: The ADC sampling frequency is greater than 3.2k, and 64 points of AC data are obtained.

5. The method for detecting electricity theft in a thyristor speed regulating switch according to claim 3, wherein: The model of the single chip processor is V8530.

Images