Calibration signal generating circuit, single-phase calibration device and three-phase calibration device

Abstract

The utility model relates to the technical field of electronic electric energy meters, and discloses a calibration signal generating circuit, a single-phase calibration device and a three-phase calibration device, which comprise a power supply, a signal generating unit and a metering unit, the first input end and the second input end of the signal generating unit are respectively and correspondingly connected with the positive end and the negative end of the power supply, and the metering unit is connected with the signal generating unit. The output end of the voltage conversion unit is connected with the input end of the metering unit, and the voltage conversion unit is used for converting power supply voltage of a power supply into MV-level voltage signals and outputting the MV-level voltage signals; and the metering unit is arranged in a base meter of the electric energy meter and is used for outputting a calibration signal based on the MV-level voltage signal. The calibration signal generating circuit can replace a professional table body to generate standard MV-level calibration signals and input the standard MV-level calibration signals into the base meter of the electric energy meter, the precision of the MV-level calibration signals is high, the cost of the calibration signal generating circuit is low, and the calibration signal generating circuit can be suitable for base meters of various electric energy meters.

Description

Technical Field

[0001] The utility model relates to the technical field of electronic electric energy meters, in particular to a calibration signal generating circuit, a single-phase calibration device and a three-phase calibration device. Background Art

[0002] The rail-type watt-hour meter is generally divided into two parts: a base meter and an external Rogowski coil. The rail-type watt-hour meter has specified error requirements for both the base meter and the entire machine. That is, the sampling signal input to the base meter should be the MV-level voltage signal output by the Rogowski coil. Therefore, a special dedicated platform is required to calibrate the base meter, which is expensive.

[0003] The base meter is required to be able to match any Rogowski coil of any manufacturer and any model, and after matching, it can meet the error accuracy required by the technical specifications. However, the Rogowski coil itself has large angular difference and ratio difference. If the combination of Rogowski coil and base meter is used for calibration, the base meter already includes the error of the Rogowski coil. When a Rogowski coil is replaced in actual use, it may cause error offset to exceed the tolerance and the calibration result to be inaccurate. Utility Model Content

[0004] Therefore, the technical problem to be solved by the present invention is to solve the problem that the ordinary table and Rogowski coil in the prior art have low precision, resulting in inaccurate base meter calibration of the electric energy meter, thereby providing a calibration signal generating circuit, a single-phase calibration device and a three-phase calibration device.

[0005] In order to achieve the above object, the utility model provides the following technical solutions:

[0006] In a first aspect, the utility model provides a calibration signal generating circuit, comprising: a power supply, a signal generating unit and a metering unit, wherein the signal generating unit has a first input terminal and a second input terminal respectively connected to the positive terminal and the negative terminal of the power supply, and an output terminal connected to the input terminal of the metering unit, and is used for converting the power supply voltage of the power supply into an MV-level voltage signal and then outputting it; the metering unit is arranged in a base meter of the electric energy meter, and is used for outputting a calibration signal based on the MV-level voltage signal.

[0007] The calibration signal generating circuit provided by the utility model has a signal generating unit which can convert the supply voltage into a standard MV-level voltage signal and input it into a base meter, and is applicable to various types of base meters; moreover, the generation of the MV-level voltage signal does not require the use of a professional table, so the circuit does not involve precision components and has low cost, can significantly reduce the deviation of the output calibration signal, and improve the accuracy of the calibration signal.

[0008] In an optional embodiment, the signal generating unit includes: a mutual inductor and a sampling resistor, wherein the mutual inductor has a first input terminal and a second input terminal respectively connected to the positive terminal and the negative terminal of the power supply, a first output terminal and a second output terminal respectively connected to the first terminal and the second terminal of the sampling resistor, and a first output terminal and a second output terminal also connected to the first input terminal and the second input terminal of the metering unit, and is used to convert the power supply voltage into an MA level current signal; the sampling resistor is used to convert the MA level current signal into an MV level voltage signal and then input it into the metering unit.

[0009] The calibration signal generating circuit provided by the utility model has a signal generating unit which only includes a mutual inductor and a sampling resistor. Compared with a professional platform, the calibration signal generating circuit provided by the utility model has fewer components, a simpler connection method, and a low cost, and can significantly reduce the deviation of the output calibration signal and improve the accuracy of the calibration signal.

[0010] In an optional implementation, the sampling resistor is an ohm-level low-temperature drift resistor.

[0011] The calibration signal generating circuit provided by the utility model further reduces the deviation of the calibration signal output by the signal generating circuit by adopting a low-temperature drift resistor whose resistance value changes less with temperature, thereby improving the accuracy of the calibration signal.

[0012] In the second aspect, the utility model provides a single-phase calibration device, comprising: a host computer and the calibration signal generating circuit of the first aspect, wherein the host computer, whose input end is connected to the output end of the metering unit, and whose output end is connected to the control end of the base meter of the single-phase electric energy meter, is used to calibrate the base meter of the single-phase electric energy meter based on the calibration signal.

[0013] The single-phase calibration device provided by the utility model has a calibration signal generating circuit that generates an MV-level voltage signal, and a metering unit outputs an accurate calibration signal based on the MV-level voltage signal, so that a host computer can calibrate a base meter of a single-phase electric energy meter based on the calibration signal. The calibration accuracy is high, and since no high-precision table equipment is required, the single-phase calibration device has a low cost.

[0014] In an optional implementation, the supply voltage is a single-phase voltage.

[0015] In the third aspect, the utility model provides a three-phase calibration device, comprising: a host computer, the power supply of the first aspect, a metering unit and three signal generating units of the first aspect, wherein the first input terminal and the second input terminal of each signal generating unit are correspondingly connected to the positive terminal and the negative terminal of the power supply, the output terminal of each signal generating unit is connected to the input terminal of the metering unit, and each signal generating unit is used to convert the voltage of the power supply into an MV-level voltage signal and then output it; the input terminal of the host computer is connected to the output terminal of the metering unit, and the output terminal of the host computer is connected to the control terminal of the base meter of the electric energy meter, and the host computer is used to calibrate the base meter based on the calibration signal output by the metering unit.

[0016] The three-phase calibration device provided by the utility model has a calibration signal generating circuit that generates a MV-level voltage signal, and a metering unit outputs an accurate calibration signal based on the MV-level voltage signal, so that a host computer can calibrate a base meter of a three-phase electric energy meter based on the calibration signal. The calibration accuracy is high, and since no high-precision table equipment is required, the cost of the three-phase calibration device is low.

[0017] In an optional implementation, the supply voltage is a three-phase voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the specific implementation methods of the utility model or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 A composition diagram of a specific example of a calibration signal generating circuit according to an embodiment of the present utility model;

[0020] Figure 2 A structural diagram of a specific circuit of a calibration signal generating circuit according to an embodiment of the utility model;

[0021] Figure 3 A structural diagram of a specific circuit of a single-phase calibration device according to an embodiment of the utility model;

[0022] Figure 4 This is a structural diagram of a specific circuit of a three-phase calibration device according to an embodiment of the utility model. DETAILED DESCRIPTION

[0023] The technical solution of the utility model will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0024] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0025] In the description of the present utility model, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, it can also be the internal connection of two components, it can be a wireless connection, or it can be a wired connection. For ordinary technicians in this field, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0026] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0027] Related technology When calibrating the base meter of an electric energy meter, the base meter needs to receive the MV-level voltage signal output by the Rogowski coil. However, since the Rogowski coil itself has large angular differences and ratio differences, when the Rogowski coil is used in combination with the base meter of the electric energy meter for calibration operations, the base meter also contains the error of the Rogowski coil. Therefore, when it is replaced with a Rogowski coil of another model, the error of the new Rogowski coil cannot match the error in the calibrated base meter, resulting in a large error offset, low accuracy in subsequent use, and a small scope of application of the calibrated base meter. To avoid errors introduced by Rogowski coils, technicians in this field usually use professional tables to output MV-level voltage signals, but professional tables require special customization, are expensive, and cannot be widely used. To solve the above problems,

[0028] This embodiment provides a calibration signal generating circuit 1, such as Figure 1As shown, it includes: a power supply 11, a signal generating unit 12 and a metering unit 13, wherein the signal generating unit 12 has a first input terminal and a second input terminal respectively connected to the positive terminal and the negative terminal of the power supply 11, and an output terminal thereof is connected to the input terminal of the metering unit 13, and is used for converting the power supply voltage of the power supply 11 into an MV-level voltage signal and then outputting it; the metering unit 13 is arranged in the base meter of the electric energy meter, and is used for outputting a calibration signal based on the MV-level voltage signal.

[0029] Specifically, Figure 1 In the example, when the electric energy meter is a single-phase electric energy meter or a three-phase electric energy meter, the power supply 11 is used to output a DC supply voltage or an AC supply voltage to the signal generating unit 12. In order to meet the requirement of the base meter of the electric energy meter to receive the MV-level voltage signal, the signal generating unit 12 can be a mutual inductor, a transformer or other device that can convert the supply voltage into a MV-level voltage signal. The metering unit 13 samples and processes the MV-level voltage signal and then outputs a calibration signal. The operator can calibrate the base meter of the electric energy meter according to the calibration signal.

[0030] It should be noted that the metering unit in this embodiment has a built-in mature sampling program control method in the prior art. Those skilled in the art can program the metering unit according to the mature sampling program in the prior art in combination with actual needs, and adjust the sampling and output logic. That is, this embodiment only protects the structure of the calibration signal generating circuit, and does not protect the internal control logic of the metering unit and the method of sampling and outputting the calibration signal.

[0031] The present embodiment utilizes a signal generating unit to replace the existing Rogowski coil to generate an MV-level voltage signal, thereby effectively avoiding the problems of high angular difference and ratio difference inherent in the Rogowski coil, and making the calibration signal output by the calibration signal generating circuit more accurate; at the same time, since the calibration signal generating circuit provided by the present embodiment does not include a Rogowski coil, the base meter does not include an error matching the Rogowski coil, and it can be avoided that when the Rogowski coil is replaced, the error inherent in the base meter matching the old Rogowski coil cannot match the error of the new Rogowski coil, thereby improving the application range of the base meter.

[0032] The calibration signal generating circuit provided in this embodiment has a signal generating unit that can convert the supply voltage into a standard MV-level voltage signal and input it into a base meter, and is applicable to various types of base meters. Moreover, the generation of the MV-level voltage signal does not require the use of a professional platform, so the circuit does not involve precision components and has low cost, and can significantly reduce the deviation of the output calibration signal, thereby improving the accuracy of the calibration signal.

[0033] In some optional embodiments, such as Figure 2As shown, the signal generating unit 12 includes: a mutual inductor 121 and a sampling resistor R0, wherein the mutual inductor 121 has a first input terminal and a second input terminal respectively connected to the positive terminal and the negative terminal of the power supply 11, a first output terminal and a second output terminal respectively connected to the first terminal and the second terminal of the sampling resistor, and a first output terminal and a second output terminal are also connected to the first input terminal and the second input terminal of the metering unit, and is used to convert the power supply voltage into an MA level current signal; the sampling resistor R0 is used to convert the MA level current signal into an MV level voltage signal and then input it into the metering unit 13.

[0034] Specifically, Figure 2 In the embodiment, the sampling resistor R0 is an ohm-class resistor, and the mutual inductor 121 is a high-precision MA-class mutual inductor. Under the action of the power supply voltage of the power supply 11, the primary side of the mutual inductor 121 induces a corresponding MA-class current signal flowing through the sampling resistor R0 on its secondary side, so that a potential difference is generated between the two ends of the sampling resistor R0, and the metering unit 13 receives the MV-class voltage signal output by the sampling resistor R0. Since the calibration signal generating circuit provided in this embodiment only includes the power supply 11, the mutual inductor 121, the sampling resistor R0 and the metering unit, the circuit structure is simple, the variables are few, the factors affecting the accuracy of the calibration signal are few, the error of the Rogowski coil can be avoided, and the accuracy of the output calibration signal is improved.

[0035] Preferably, the transformer 121 is a 1(10) / 1mA-20 0.02 level transformer.

[0036] Preferably, in order to further reduce the deviation of the calibration signal output by the signal generating circuit and improve the accuracy of the calibration signal, the sampling resistor R0 uses an ohm-level low temperature drift resistor with small temperature variation, and its parameters are 20Ω, 0.1% accuracy, and 25PPM / °C.

[0037] This embodiment provides a single-phase calibration device, such as Figure 3 As shown, it includes: a host computer 2 and a calibration signal generating circuit 1 of the above embodiments and any optional implementation manner thereof, wherein the host computer 2, whose input end is connected to the output end of the metering unit 13, and whose output end is connected to the control end of the base meter of the single-phase electric energy meter, is used to calibrate the base meter of the single-phase electric energy meter based on the calibration signal.

[0038] For example, Figure 3 In the example, a single-phase electric energy meter with a base meter calibration point of 0.5L 100A is used. If a 500A / 400mV Rogowski coil is used, when the Rogowski coil detects a current signal of 500A, the Rogowski coil should output a voltage signal of 400mV, and when the Rogowski coil detects a current signal of 100A, the Rogowski coil should output a voltage signal of 80mV.

[0039] For example, Figure 3 In this embodiment, a 1(10) / 1mA-20 0.02 level mutual inductor 121 is installed on the platform, the power supply 11 outputs a current of 4A to the platform, the sampling resistor R0 is a 20Ω, 0.1% accuracy, 25PPM / ℃ low temperature drift resistor, and a standard 80mV voltage signal is output across the sampling resistor. This voltage signal is the same as the voltage signal output when the Rogowski coil detects a current signal of 0.5L 100A. Therefore, when the metering unit 13 samples the 80mV voltage signal, it will determine that the meter is the 0.5L 100A current detected by the Rogowski coil, and thus output a calibration signal to the upper computer, so that the upper computer performs a calibration operation on the base meter based on the calibration signal.

[0040] It should be noted that, as disclosed in Patent No. CN117647767A, the "first calibration voltage" is provided to the metering chip of the guide rail meter control circuit by a 10-core cable for sampling and processing, and the "first calibration voltage" is simultaneously input into the AD port of the calibration device main control chip U1 for analog-to-digital conversion, and the "second calibration voltage" data for correction is generated after processing and calculation by the U1 main control chip; and then sent to the MCU main control chip of the electric energy meter control board through the LOSS_S2 single-line communication mode for correction and calibration of the "first calibration voltage" obtained by the metering chip, that is, when the metering chip collects the first calibration voltage, the main control chip generates the second calibration voltage according to the first calibration voltage, and the main control chip of the electric energy meter control board corrects and calibrates the first calibration voltage based on the second calibration voltage, that is, the method in this embodiment that the metering chip converts the collected MV-level voltage signal into a calibration signal, and the host computer calibrates the base meter of the electric energy meter according to the calibration signal is a calibration method disclosed in the prior art, which will not be repeated here.

[0041] The single-phase calibration device provided in this embodiment has a calibration signal generating circuit that generates a MV-level voltage signal, and the metering unit outputs an accurate calibration signal based on the MV-level voltage signal, so that the host computer can calibrate the base meter of the single-phase electric energy meter based on the calibration signal. The calibration accuracy is high, and since no high-precision table equipment is required, the single-phase calibration device has low cost.

[0042] This embodiment provides a three-phase calibration device, such as Figure 4As shown, it includes: a host computer 2, a power supply 11 of the above embodiment and any optional implementation manner thereof, a metering unit 13 and three signal generating units 12 of the first aspect, wherein the first input terminal and the second input terminal of each signal generating unit are correspondingly connected to the positive terminal and the negative terminal of the power supply, the output terminal of each signal generating unit is connected to the input terminal of the metering unit, and each signal generating unit is used to convert the voltage of the power supply into an MV-level voltage signal and then output it; the input terminal of the host computer is connected to the output terminal of the metering unit, the output terminal of the host computer is connected to the control terminal of the base meter of the electric energy meter, and the host computer is used to calibrate the base meter based on the calibration signal output by the metering unit.

[0043] For example, Figure 4 In the example, a three-phase electric energy meter with a calibration point of 0.5L 100A as the base meter of the electric energy meter is used. The power supply voltage of the power supply 11 is a three-phase voltage, and the voltage signals in the circuit are all AC signals. Since the secondary and primary of the mutual inductor 121 are isolated, the three secondary signals output by the three signal generating units 12 can be simultaneously input into the base meter for three-phase simultaneous calibration. The method of calibrating the base meter of the three-phase electric energy meter using the three-phase calibration device is consistent with the operation method of the single-phase calibration device, and will not be repeated here.

[0044] It should be noted that, since the transformation ratio of the Rogowski coil is 100A and the output is 80mV, when the Rogowski coil is used normally, the pulse constant of the base meter is 200, and the transformation ratio of the calibration signal generating circuit in this embodiment is 4A and the output is 80mV, and the current is reduced by 25 times. Therefore, when the calibration signal generating circuit in this embodiment is used for calibration and error detection, the pulse constant of the table body needs to be adjusted to 25 times the constant of the Rogowski coil, that is, 5000.

[0045] The three-phase calibration device provided in this embodiment has a calibration signal generating circuit that generates a MV-level voltage signal, and a metering unit outputs an accurate calibration signal based on the MV-level voltage signal, so that the host computer can calibrate the base meter of the three-phase electric energy meter based on the calibration signal. The calibration accuracy is high, and since no high-precision table equipment is required, the cost of the three-phase calibration device is low.

[0046] Although the embodiments of the present invention are described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A calibration signal generating circuit, characterized in that: include: Power supply, signal generating unit and metering unit, among which, A signal generating unit, whose first input terminal and second input terminal are respectively connected to the positive terminal and negative terminal of the power supply, and whose output terminal is connected to the input terminal of the metering unit, and is used for converting the power supply voltage of the power supply into an MV-level voltage signal and then outputting it; The metering unit is arranged in a base meter of the electric energy meter and is used for outputting a calibration signal based on the MV-level voltage signal.

2. The calibration signal generating circuit according to claim 1, characterized in that: The signal generating unit includes: a mutual inductor and a sampling resistor, wherein: A mutual inductor, whose first input terminal and second input terminal are respectively connected to the positive terminal and negative terminal of the power supply, whose first output terminal and second output terminal are respectively connected to the first terminal and second terminal of the sampling resistor, and whose first output terminal and second output terminal are also connected to the first input terminal and second input terminal of the metering unit, and is used to convert the power supply voltage into a MA level current signal; The sampling resistor is used to convert the MA level current signal into a MV level voltage signal and then input it into the metering unit.

3. The calibration signal generating circuit according to claim 2, characterized in that: The sampling resistor is an ohm-level low-temperature drift resistor.

4. A single-phase calibration device, characterized in that: include: A host computer and a calibration signal generating circuit as claimed in any one of claims 1 to 3, wherein: The host computer has an input end connected to the output end of the metering unit and an output end connected to the control end of the base meter of the single-phase electric energy meter, and is used to calibrate the base meter of the single-phase electric energy meter based on the calibration signal.

5. The single-phase calibration device according to claim 4, characterized in that: The supply voltage is single-phase voltage.

6. A three-phase calibration device, characterized in that: include: A host computer, a power supply according to any one of claims 1 to 3, the metering unit and three signal generating units according to any one of claims 1 to 3, wherein: The first input terminal and the second input terminal of each of the signal generating units are connected to the positive terminal and the negative terminal of the power supply respectively, the output terminal of each of the signal generating units is connected to the input terminal of the metering unit, and each of the signal generating units is used to convert the voltage of the power supply into an MV-level voltage signal and then output it; The input end of the host computer is connected to the output end of the metering unit, and the output end of the host computer is connected to the control end of the base meter of the electric energy meter. The host computer is used to calibrate the base meter based on the calibration signal output by the metering unit.

7. The three-phase calibration device according to claim 6, characterized in that: The supply voltage is three-phase voltage.

Images