Smart meter and harmonic calibration method

Abstract

The application discloses a smart electric meter and a harmonic calibration method, and belongs to the technical field of smart electric meters. The smart electric meter comprises a control module, a communication module, a first filter circuit, a harmonic generation module and a metering module. The control module is connected with the communication module, the first filter circuit, the harmonic generation module and the metering module in signal connection. The metering module is connected with the first filter circuit or connected with a power grid. The control module periodically controls the first filter circuit and the harmonic generation module to be connected to the power grid. When the control module controls the first filter circuit and the harmonic generation module to be connected to the power grid, the harmonic generation module generates a standard harmonic signal, and the metering module detects a power grid signal superimposed with the harmonic signal generated by the harmonic generation module. The application provides a smart electric meter capable of having a harmonic self-calibration function.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of smart meters, in particular to a smart meter and a harmonic calibration method. BACKGROUND

[0002] With the increase in the number of distributed photovoltaic power stations and the decrease in the proportion of thermal power, hydropower and nuclear power generation in main grid power supply, the harmonic components in the power grid will be more complex. Harmonic identification is the basis of harmonic control. The key technology for identifying harmonic sources is to accurately measure the harmonic power size and power factor angle, that is, to accurately measure the amplitude and phase difference of the same measurement point, the same phase and the same harmonic voltage and harmonic current.

[0003] The existing technology generally uses a harmonic vector measurement method based on multi-channel synchronous data acquisition and rectangular window data interception for the harmonic error measurement of a smart meter. The synchronization error generated by multi-channel synchronous data acquisition increases the measurement error of the phase difference between channels, and the frequency spectrum leakage generated by rectangular window data interception increases the measurement error of the harmonic voltage and harmonic current amplitude.

[0004] In summary, there is currently a lack of an intelligent smart meter and a harmonic calibration method that can timely detect measurement harmonic errors on the market. SUMMARY

[0005] The summary part of the present application is used to introduce the concepts in a simple form, which will be described in detail in the specific embodiments part. The summary part of the present application is not intended to identify the key features or essential features of the claimed technical solutions, nor is it intended to limit the scope of the claimed technical solutions.

[0006] As a first aspect of the present application, in order to solve the technical problems mentioned in the background part, some embodiments of the present application provide a smart meter, comprising: a control module, a communication module, a first filter circuit, a harmonic generation module, a metering module; the control module is respectively connected with the communication module, the first filter circuit, the harmonic generation module and the metering module in signal connection; the metering module is connected with the first filter circuit or connected with the power grid; the control module periodically controls the first filter circuit and the harmonic generation module to be connected to the power grid; when the control module controls the first filter circuit and the harmonic generation module to be connected to the power grid, the harmonic generation module generates a standard harmonic signal, and the metering module detects the power grid signal superimposed with the harmonic signal generated by the harmonic generation module; the control module compares the harmonic signal detected by the metering module with the standard harmonic signal generated by the harmonic generation module, and if the voltage fluctuation of the corresponding harmonic signal is greater than a preset threshold, the control module sends a signal of harmonic signal measurement error exceeding the standard to the server of the power supply company.

[0007] Further, the relay circuit comprises a first branch, a second branch and a relay control circuit, the first branch and the second branch are connected to the power grid, and the relay control circuit is connected to the control module.

[0008] By designing the relay circuit, the control module can control the turn-on and turn-off of the first branch and the second branch, so that when the harmonic generation module and the first filter circuit are connected to the power grid, a too complex circuit structure does not need to be set.

[0009] Further, the first filter circuit is arranged in the second branch, and the relay control circuit controls the first branch or the second branch to be connected to the metering module for measurement.

[0010] Further, the relay circuit comprises a relay, a normally closed contact of the relay is connected to the first branch, and a normally open contact of the relay is connected to the second branch.

[0011] Further, the harmonic generation module comprises a signal source variable module and a signal self-variable module, the signal source variable module couples the harmonic signal into the signal self-variable module, and the signal self-variable module is used to deliver a standard harmonic signal to the metering module.

[0012] Further, the signal self-variable module comprises a first coil and a first core, the first coil is wound on the first core; the signal source variable module comprises a second coil and a second core, the second coil is wound on the second core, and the second coil is connected to a standard harmonic power supply; the second core comprises a winding part and a magnetic conduction part arranged at the head and tail of the winding part, the magnetic conduction part is folded towards the direction of the first core, and the first core and the second core do not contact each other, and the first core is configured in a ring shape.

[0013] By configuring the first core and the second core in the above shape, the magnetic field generated by the first core is difficult to be introduced into the second core due to the gap between the winding parts, thereby avoiding the influence of the power grid signal on the harmonic signal source. The magnetic field generated by the second core can be directly introduced into the first core through the magnetic conduction part. Therefore, the signal strength coupled to the power grid can be increased on the basis of avoiding the influence of the power grid signal on the harmonic signal source.

[0014] Further, the second filter circuit is connected between the metering module and the power grid output by the smart meter when the harmonic generation module is connected to the power grid, the harmonic signal generated by the harmonic generation module is input to the second filter circuit after passing through the metering module, and the second filter circuit filters out the harmonic signal generated by the harmonic generation module.

[0015] By setting up a second filtering circuit, the harmonic signals generated by the harmonic generation module can be prevented from entering the power grid and causing adverse effects on other devices on the power grid. This minimizes the impact on other meters on the power grid when the smart meter performs harmonic detection, and avoids the presence of unnecessary and useless electrical signals on the power grid.

[0016] As a second aspect of this application, in order to solve the technical problems mentioned in the background section above, some embodiments of this application provide a harmonic calibration method, including the following steps:

[0017] Step 1: The control module periodically controls the first filter circuit and the harmonic generation module to connect to the power grid. When the first filter circuit and the harmonic generation module are connected to the power grid, step 2 is executed. When the first filter circuit and the harmonic generation module are not connected to the power grid, the smart meter works normally.

[0018] Step 2: The first filter circuit filters out the specified harmonic signal input from the power grid to the metering module, and the harmonic generation module generates a standard harmonic signal and couples the standard harmonic signal to the power grid circuit under test.

[0019] Step 3: The metering module detects the power grid signal superimposed with the harmonic signal emitted by the harmonic generation module;

[0020] Step 4: The control module compares the harmonic signal detected by the metering module with the standard harmonic signal generated by the harmonic generation module. If the voltage fluctuation of the corresponding harmonic signal is greater than the preset threshold, the control module sends a signal indicating that the harmonic signal measurement error exceeds the tolerance to the power supply company's server.

[0021] Furthermore, the method for controlling the connection of the first filter circuit and the harmonic generation module to the power grid and the metering module in step 1 is as follows: the control module energizes the relay control circuit, causing the normally open contact of the relay switch to close and the normally closed contact to open, thereby connecting the metering module to the second branch, thus connecting the metering module to the second branch.

[0022] The harmonic generator is connected to and disconnected from the power grid using a relay, which has a fast response speed and good response effect.

[0023] Furthermore, the standard harmonic signals generated by the harmonic generation module in step 2 have frequencies of f1, f2, f3...f n The voltage amplitudes are A1, A2, A3...A n One or more harmonic signals; simultaneously, the first filter circuit filters frequencies ranging from f1, f2, f3...f n One or more frequencies.

[0024] The beneficial effects of this application are as follows:

[0025] (1) In order to solve the problem that the metering module of the smart meter may have error when measuring the harmonic, a harmonic generator module is adopted to generate a standard harmonic signal with known frequency and known amplitude. In the harmonic signal measured by the metering module, the voltage fluctuation between the standard harmonic and the measured harmonic is compared by using the frequency corresponding relationship, and then the error of the metering module for harmonic measurement is determined.

[0026] (2) When measuring whether the metering module has error, the metering module is not directly removed from the branch in which the power grid is located, but a first filter circuit is adopted to filter out the harmonic frequency generated by the harmonic generator module, so as to test the accuracy of the metering module on the original circuit. Therefore, in addition to the standard harmonic transmitted by the harmonic generator module, there are also signals of other frequencies in the power grid, thereby providing the environment existing in actual work when measuring the accuracy of the metering module. BRIEF DESCRIPTION OF DRAWINGS

[0027] The accompanying drawings, which form a part of this application, are included to provide a further understanding of the application and are incorporated in and constitute a part of this application. The drawings illustrate embodiments of the present application and, together with the description, serve to explain the application. It is expressly understood that the drawings are illustrative only and that the claimed application is not limited to the specific

[0028] In addition, throughout the drawings, the same or similar reference numerals designate the same or similar elements. It should be understood that the drawings are schematic, and the elements and elements are not necessarily drawn according to the scale.

[0029] In the drawings:

[0030] Figure 1 The structural schematic diagram of the smart meter provided for some embodiments of the present application is shown.

[0031] Figure 2 The structural schematic diagram of the smart meter provided for some embodiments of the present application is shown, and the processing module and the communication module are omitted.

[0032] Figure 3 The structural schematic diagram of the smart meter provided for some embodiments of the present application is shown, and the processing module and the communication module are omitted.

[0033] Figure 4 The structural schematic diagram of the harmonic generator of the present application is shown.

[0034] Figure 5 The structural schematic diagram of another harmonic generator of the present application is shown. DETAILED DESCRIPTION

[0035] Embodiments of the present disclosure will be described below in greater detail with reference to the accompanying drawings. While certain embodiments of the present disclosure are shown in the drawings, it is understood that the present disclosure can be embodied in various forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that the present disclosure will be thoroughly and completely understood. It should be understood that the drawings of the present disclosure and the embodiments are only for exemplary purposes and are not intended to limit the scope of protection of the present disclosure.

[0036] In addition, it should be further noted that, for ease of description, only the parts related to the present application are shown in the drawings. The embodiments in the present disclosure and the features in the embodiments can be combined with each other without conflict.

[0037] The present disclosure will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0038] Referring to Figures 1-2 :

[0039] The smart meter comprises a control module, a communication module, a first filter circuit, a harmonic generation module, and a metering module. The control module is connected with the communication module, the first filter circuit, the harmonic generation module, and the metering module. The metering module is connected with the first filter circuit or connected with the power grid.

[0040] The control module periodically controls the first filter circuit and the harmonic generation module to be connected to the power grid. When the control module controls the first filter circuit and the harmonic generation module to be connected to the power grid, the harmonic generation module generates one or more groups of standard harmonic signals with frequencies f1, f2, f3...f n and voltage amplitudes A1, A2, A3...A n The metering module detects the power grid signal superimposed with the harmonic signal generated by the harmonic generation module and identifies the standard harmonic signal with frequencies f1, f2, f3...f n and voltage amplitudes B1, B2, B3...B n from the power grid signal. If, among the voltage fluctuations |A1-B1|, |A2-B2|, |A3-B3|...|A n -B n , there is a group of data exceeding the preset threshold α, the control module sends a signal of large error of the metering module to the server of the power company.

[0041] In the working process of the smart meter, the detection of the harmonic signal is more concerned about the amplitude of the harmonic signal, and the phase and frequency of the harmonic signal are concerned about less. Therefore, the relationship between the harmonic signal generated by the harmonic generation module and the harmonic signal detected by the metering module can be established by the frequency of the harmonic signal. For example, the frequency of the harmonic A generated by the harmonic generation module is 10 kHz, and the frequency of the harmonic A' detected by the metering module is also 10 kHz. The harmonic A and the harmonic A' can be established in a corresponding relationship.

[0042] When the phase of the harmonic signal needs to be accurately identified, the phase of the harmonic signal generated by the harmonic generation module can be compared with the phase of the harmonic signal detected by the metering module. For example, the frequency of the harmonic A generated by the harmonic generation module is 10 kHz, and the phase is θ. The frequency of the harmonic A' detected by the metering module is also 10 kHz, and the phase is θ'. The phase difference θ'-θ of the harmonic A and the harmonic A' is evaluated for error.

[0043] For example, the preset value α is set to 1V; if the harmonic signal on the power grid is 100MHz, the amplitude is 220V, and after the first filter circuit is connected to the power grid, the harmonic signal on the power grid is filtered by the first filter circuit, then at this time the harmonic generation module generates a standard harmonic with a frequency of 100MHz and an amplitude of 2V, and the frequency of the harmonic signal detected by the metering module is 100MHz and the amplitude is 2.2V. At this time, the voltage fluctuation is 0.2v, which is less than the preset value, so the metering module is accurate, and the smart meter works normally. The smart meter can periodically test the smart meter after the control module periodically controls the first filter circuit to be connected to the power grid. It can be predicted that in actual work, in order to detect the accuracy of the metering module in measuring different frequency harmonics, a plurality of frequency harmonic signals can be continuously generated and then sent to the metering module to determine whether the metering of the metering module is accurate.

[0044] As shown in Figure 2 In order to facilitate the control of the first filter circuit to be connected to the power grid, the electrical signal on the power grid is transmitted to the harmonic generation module after being filtered by the first filter circuit, and then the standard harmonic signal generated by the harmonic generation module and the remaining signals of the harmonic signal in the power grid except the filter frequency of the filter circuit are input to the metering module. The application also provides the following technical solutions:

[0045] The intelligent electric meter further comprises a relay circuit, the relay circuit comprising a first branch, a second branch and a relay control circuit, the first branch and the second branch being connected to the power grid, and the relay control circuit being connected to the control module. The relay circuit comprises a relay, the normally closed contact of the relay being connected to the first branch, and the normally open contact of the relay being connected to the second branch. The first filter circuit and the harmonic generation module are arranged in the second branch. Therefore, when the relay is powered on, the normally open contact of the relay is closed, and the normally closed contact of the relay is opened, at this time, the first filter circuit and the harmonic generation module are connected between the power grid and the metering module.

[0046] Further, when the harmonic generation module generates the standard harmonic signal, a harmonic power supply is needed to form the harmonic signal. However, in the present scheme, the harmonic signal generated by the harmonic generation module and the remaining signals on the power grid are input into the metering module, so in fact the harmonic signal needs to be coupled to the power grid signal. Specifically, the harmonic generation module comprises a signal source variable module and a signal self-variable module, the signal source variable module couples the harmonic signal into the signal self-variable module, and the signal self-variable module is used to deliver the standard harmonic signal to the metering module.

[0047] Reference Figure 4 The signal self-variable module comprises a first coil 12 and a first core 11, and the first coil is wound around the first core; the signal source variable module comprises a second coil 22 and a second core 21, and the second coil is wound around the second core, and the second coil is connected to a standard harmonic power supply; the second core comprises a winding part 211 and a magnetic conduction part 212 arranged at the head and tail of the winding part, the magnetic conduction part is folded towards the direction of the first core, and the first core and the second core do not contact each other, and the first core is configured in a ring shape. Therefore, when the harmonic generation module needs to send the standard harmonic signal to the metering module, the standard harmonic power supply is started, and then a changing magnetic field is generated at the position of the second coil, these magnetic fields will be introduced into the first core along the magnetic conduction part, and then an induced current is coupled into the first coil, thereby generating the required harmonic signal.

[0048] Of course, because the signal coupled from the second coil to the first coil will be attenuated to a certain extent, when the standard harmonic signal we need is obtained, the harmonic generation module needs to be tested to calculate the gain coefficient Au of the harmonic generator. Au = α / β, wherein α is the amplitude of the harmonic signal input into the second coil, and β is the amplitude of the harmonic signal input into the first coil.

[0049] The signal coupling method provided in this application avoids the influence of the grid current on the harmonic signal source during use, ensuring that the standard harmonic signal and the grid harmonic signal can be synchronously input to the metering module. Furthermore, the second iron core is U-shaped; the gap formed between the concave section and the winding section reduces the influence of the magnetic field generated from the first coil on the harmonic signal source, while the magnetic field generated by the second coil can be directly introduced into the first iron core along the end of the concave section. Because the first iron core is constructed as a ring, the magnetic field generated by the first coil flows along the ring structure of the first iron core, preventing leakage to the outside, reducing the possibility of magnetic conduction to the second iron core, and increasing the stability of the entire system.

[0050] refer to Figure 5 Besides the coupling methods of the signal source converter module and the signal self-converter module provided in this application, the first iron core and the second iron core can also be configured with other shapes to achieve the effect of coupling harmonic signals into the power grid. Figure 5 In the provided method, aligning the ends of the first coil and the second coil can increase the coupling efficiency of the first coil and the second coil.

[0051] refer to Figure 3 To prevent the harmonic signals generated by the harmonic generation module from adversely affecting the power grid, the smart meter also includes a second filtering circuit. When the harmonic generation module is connected to the power grid, the second filtering circuit is connected between the metering module and the smart meter's output power grid. The harmonic signals generated by the harmonic generation module are input to the second filtering circuit after passing through the metering module, and the second filtering circuit filters out the harmonic signals generated by the harmonic generation module. The connection method of the second filtering circuit can refer to the connection method of the first filtering circuit.

[0052] Example 2: Based on the above-mentioned smart meter, this solution also proposes a harmonic calibration method for timely detection of faulty smart meters. The harmonic calibration method includes the following steps:

[0053] Step 1: The control module periodically controls the first filter circuit and the harmonic generation module to connect to the power grid. When the first filter circuit and the harmonic generation module are connected to the power grid, step 2 is executed. When the first filter circuit and the harmonic generation module are not connected to the power grid, the smart meter works normally.

[0054] The method for controlling the connection of the first filter circuit and the harmonic generation module to the power grid and the metering module in step 1 is as follows: the control module supplies power to the relay control circuit, so that the normally open contact of the relay switch closes and the normally closed contact opens.

[0055] In the embodiment, the harmonic generation module and the first filter circuit are both arranged on the relay circuit, so that the harmonic generation module and the first filter circuit can be connected to or disconnected from the power grid.

[0056] Step 2: The first filter circuit filters out the specified harmonic signals input by the power grid to the metering module, and the harmonic generation module generates standard harmonic signals and couples the standard harmonic signals to the power grid circuit to be measured.

[0057] The standard harmonic signals generated by the harmonic generation module in step 2 are one or more groups of harmonic signals with frequencies f1, f2, f3... f n and voltage amplitudes A1, A2, A3... A n .

[0058] Step 3: The metering module detects the power grid signals superimposed with the harmonic signals generated by the harmonic generation module.

[0059] In step 3, the metering module measures one or more groups of harmonic signals with frequencies f1, f2, f3... f n and voltage amplitudes B1, B2, B3... B n .

[0060] Step 4: The control module compares the harmonic signals detected by the metering module with the standard harmonic signals generated by the harmonic generation module, and if the voltage fluctuation of the corresponding harmonic signals is greater than a preset threshold, the control module sends a signal of harmonic signal measurement error to the server of the power supply company.

[0061] The specific way of step 4 is to determine whether there is a group of data exceeding the preset threshold a among the voltage fluctuations |A1-B1|, |A2-B2|, |A3-B3|... |A n -B n | of the harmonic signals corresponding to the frequencies, and if so, the control module sends a signal of large error of the metering module to the server of the power supply company.

[0062] The above description is only some preferred embodiments of the present disclosure and a description of the principles of the technology applied. Those skilled in the art should understand that the scope of the application involved in the embodiments of the present disclosure is not limited to the technical solutions formed by the specific combinations of the above technical features, and should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the above inventive concept. For example, the above features are replaced with the technical features disclosed in the embodiments of the present disclosure (but not limited to) having similar functions to form technical solutions.

Claims

1. A smart meter, characterized in that, include: The system includes a control module, a communication module, a first filter circuit, a harmonic generation module, and a metering module. The control module is connected to the communication module, the first filter circuit, the harmonic generation module, and the metering module. The metering module is connected to the first filter circuit or to the power grid. The control module periodically controls the first filter circuit and the harmonic generation module to connect to the power grid. When the control module controls the first filter circuit and the harmonic generation module to connect to the power grid, the harmonic generation module generates a standard harmonic signal, and the metering module detects the power grid signal superimposed with the harmonic signal generated by the harmonic generation module. The control module compares the harmonic signal detected by the metering module with the standard harmonic signal generated by the harmonic generation module. If the voltage fluctuation of the corresponding harmonic signal is greater than a preset threshold, the control module sends a signal indicating that the harmonic signal measurement error exceeds the tolerance to the power supply company's server. The harmonic generation module includes a signal source converter module and a signal self-converter module. The signal source converter module couples the harmonic signal into the signal self-converter module, and the signal self-converter module is used to transmit the standard harmonic signal to the metering module. It also includes a second filtering circuit. When the harmonic generation module is connected to the power grid, the second filtering circuit is connected between the metering module and the smart meter output power grid. The harmonic signal generated by the harmonic generation module is input to the second filtering circuit after passing through the metering module. The second filtering circuit filters out the harmonic signal generated by the harmonic generation module.

2. The smart meter according to claim 1, characterized in that: It also includes a relay circuit, which includes a first branch, a second branch, and a relay control circuit. Both the first and second branches are connected to the power grid, and the relay control circuit is connected to the control module.

3. The smart meter according to claim 2, characterized in that: The first filter circuit is set in the second branch, and the relay control circuit controls the first branch or the second branch to connect to the metering module for measurement.

4. The smart meter according to claim 2, characterized in that: The relay circuit includes a relay, with the normally closed contact of the relay connected to the first branch and the normally open contact of the relay connected to the second branch.

5. The smart meter according to claim 1, characterized in that: The signal self-converter module includes a first coil and a first iron core, with the first coil wound around the first iron core; the signal source converter module includes a second coil and a second iron core, with the second coil wound around the second iron core and the second coil connected to a standard harmonic power supply; the second iron core includes a winding portion and magnetically conductive portions disposed at both ends of the winding portion, with the magnetically conductive portions folded towards the direction of the first iron core, and the first and second iron cores not in contact with each other, and the first iron core is constructed as a ring.

6. A harmonic calibration method, characterized in that: Includes the following steps: Step 1: The control module periodically controls the first filter circuit and the harmonic generation module to connect to the power grid. When the first filter circuit and the harmonic generation module are connected to the power grid, step 2 is executed. When the first filter circuit and the harmonic generation module are not connected to the power grid, the smart meter works normally. Step 2: The first filter circuit filters out the specified harmonic signal input from the power grid to the metering module, and the harmonic generation module generates a standard harmonic signal and couples the standard harmonic signal to the power grid circuit under test; Step 3: The metering module detects the power grid signal superimposed with the harmonic signal emitted by the harmonic generation module; Step 4: The control module compares the harmonic signal detected by the metering module with the standard harmonic signal generated by the harmonic generation module. If the voltage fluctuation of the corresponding harmonic signal is greater than the preset threshold, the control module sends a signal indicating that the harmonic signal measurement error exceeds the tolerance to the power supply company's server.

7. The harmonic calibration method according to claim 6, characterized in that: The method for controlling the connection of the first filter circuit and the harmonic generation module to the power grid and the metering module in step 1 is as follows: the control module energizes the relay control circuit, so that the normally open contact of the relay switch closes and the normally closed contact opens, thereby connecting the metering module to the second branch, thus connecting the metering module to the second branch.

8. The harmonic calibration method according to claim 6, characterized in that: In step 2, the standard harmonic signals generated by the harmonic generation module have frequencies of f1, f2, f3...f n The voltage amplitudes are A1, A2, A3...A n One or more harmonic signals; simultaneously, the first filter circuit filters frequencies ranging from f1, f2, f3...f n One or more frequencies.

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