Self-calibration device and calibration method for acquisition unit of electronic transformer

Abstract

The invention discloses a self-calibration device and calibration method for an electronic transformer acquisition unit, a DA chip outputs a standard signal, the standard signal is acquired by an AD chip after passing through a selection switch and a conditioning circuit, and a control chip carries out comparative analysis according to data acquired by the AD chip and the standard signal to realize calibration of the acquisition unit. And the measurement accuracy is effectively improved. In the long-term use process, the acquisition unit of the electronic transformer may be affected by environmental factors, electronic element aging and the like to generate measurement errors, the acquisition unit can be calibrated regularly or in real time, errors can be corrected in time, error accumulation is avoided, and it is ensured that the measurement result is always kept at a high precision level. The control chip can monitor the working state of the acquisition unit in real time and adjust the signal through the DA chip and the selection switch according to needs. The real-time monitoring and adjusting functions enable the acquisition unit to maintain stable performance under different working conditions, and the reliability of the system is improved.

Description

Technical Field

[0001] The invention belongs to the field of calibration, and relates to a self-calibration device and a calibration method for an electronic mutual inductor acquisition unit. Background Art

[0002] Electronic transformers are small in size, light in weight, free of magnetic saturation, and free of secondary open circuits. They can be easily installed in combination with primary high-voltage switchgear, effectively improving the integration of equipment, reducing land use, and facilitating installation and transportation. They have a wide range of market prospects. Electronic transformers are commonly used in new-generation substations, and are integrated in new equipment such as integrated isolation circuit breakers and intelligent GIS. "Except for the outlet relay, when any component in the device is damaged, the device should not trip by mistake." Electronic transformers use two independent A / Ds to sample protection current data, and merge multiple data channels through a merging unit and send them to the protection device, thereby meeting the requirements of completely independent protection. Therefore, the role of the acquisition unit is particularly important.

[0003] In the existing electronic transformer acquisition unit, the input signal is converted into digital quantity by the AD chip after the conditioning circuit, and then the digital quantity is output after manual calibration. Because manual calibration is required, it is time-consuming and labor-intensive, and there are subjective factors in manual calibration, which affects the calibration accuracy. Summary of the invention

[0004] The purpose of the present invention is to solve the problems in the prior art and to provide a self-calibration device and a calibration method for an electronic mutual inductor acquisition unit.

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

[0006] The present invention provides a self-calibration device for an electronic mutual inductor acquisition unit, comprising a selection switch, a conditioning circuit, an AD chip, a control chip and a DA chip;

[0007] The input end of the selection switch is connected to the first port of the DA chip, the output end of the selection switch is connected to the conditioning circuit, the output end of the conditioning circuit is connected to the first port of the AD chip, the second port of the AD chip is connected to the second port of the DA chip, the third port of the AD chip interacts with the first port of the control chip, the second port of the control chip is connected to the DA chip, and the third port of the control chip is connected to the selection switch.

[0008] Preferably, the conditioning circuit is a linear system or a second-order system.

[0009] Preferably, when the conditioning circuit is a linear system, the calculation method of the digital quantity of the transformer after calibration is as follows:

[0010]

[0011] Among them, k Am is the correction factor of the conditioning circuit, k Dm is the calibration coefficient of the DA chip, Db is the DC component of the system, k0 is the ratio of the rated analog quantity to the digital quantity, D M It is the digital quantity of the conditioning circuit.

[0012] Preferably, when the conditioning circuit is a second-order system, the calculation method of the digital quantity of the transformer after calibration is as follows:

[0013]

[0014] Among them, k Dm is the calibration coefficient of the DA chip; Db is the DC component of the system; a and b are adjustment coefficients, according to the digital value D UM and digital quantity D DA Calculated; k0 is the ratio of the rated analog quantity to the digital quantity, D M It is the digital quantity of the conditioning circuit.

[0015] The present invention provides a calibration method for a self-calibration device of an electronic mutual inductor acquisition unit, comprising:

[0016] According to the selection switch, the input of the conditioning circuit is selected as the output U of the DA chip D Or regular input U i ;

[0017] Transmit the output voltage of the conditioning circuit and the output voltage of the DA chip to the AD chip;

[0018] The control chip is used to process the output voltage of the AD chip to obtain the calibration coefficient, and the digital value of the calibrated transformer is obtained according to the correction coefficient.

[0019] Preferably, obtaining the calibration coefficient includes the calibration coefficient of the DA chip and the correction coefficient of the conditioning circuit.

[0020] Preferably, the calibration coefficient calculation method of the DA chip is as follows:

[0021]

[0022] Among them, D DAi is the digital quantity of DA chip, D UDi The digital quantity collected by the AD chip, k Di is the calibration coefficient of the DA chip output voltage, and the calibration coefficient k of the DA chip output voltage Di The average value is used to obtain the calibration coefficient k of the DA chip. Dm .

[0023] Preferably, the correction coefficient calculation method of the conditioning circuit is as follows:

[0024]

[0025] Among them, D DAi is the digital quantity of DA chip, D UMi is the digital quantity collected by the AD chip, Db is the DC component of the system, k Ai is the correction factor of the output voltage of the conditioning circuit, and the correction factor k of the output voltage of the conditioning circuit is Ai The average value is calculated to obtain the correction coefficient k of the conditioning circuit. Am .

[0026] Preferably, when the conditioning circuit is a linear system, the calculation method of the digital quantity of the transformer after calibration is as follows:

[0027]

[0028] Among them, k Am is the correction factor of the conditioning circuit, k Dm is the calibration coefficient of the DA chip, Db is the DC component of the system, k0 is the ratio of the rated analog quantity to the digital quantity, D M It is the digital quantity of the conditioning circuit.

[0029] Preferably, when the conditioning circuit is a second-order system, the calculation method of the digital quantity of the transformer after calibration is as follows:

[0030]

[0031] Among them, k Dm is the calibration coefficient of the DA chip; Db is the DC component of the system; a and b are adjustment coefficients, according to the digital value D UM and digital quantity D DA Calculated; k0 is the ratio of rated analog quantity to digital quantity, D M It is the digital quantity of the conditioning circuit.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The present invention proposes a self-calibration device for an electronic transformer acquisition unit. The DA chip outputs a standard signal, which is collected by the AD chip after passing through a selection switch and a conditioning circuit. The control chip compares and analyzes the data collected by the AD chip with the standard signal, thereby realizing the calibration of the acquisition unit and effectively improving the accuracy of the measurement. During long-term use, the electronic transformer acquisition unit may be affected by environmental factors, aging of electronic components, etc., resulting in measurement errors. The self-calibration device can calibrate the acquisition unit regularly or in real time, correct errors in time, avoid error accumulation, and ensure that the measurement results always remain at a high level of accuracy. The control chip can monitor the working status of the acquisition unit in real time, and adjust the signal through the DA chip and the selection switch as needed. This real-time monitoring and adjustment function can enable the acquisition unit to maintain stable performance under different working conditions and improve the reliability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0035] Figure 1 It is a structural diagram of the self-calibration device of the electronic mutual inductor acquisition unit of the present invention.

[0036] Figure 2 The figure is a flow chart of the calibration method of the present invention.

[0037] Figure 3 It is a structural diagram of the present invention which is only used for off-line self-calibration. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0039] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0041] In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use, it is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply 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 a limitation on the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0042] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0043] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" 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, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0044] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0045] The present invention proposes a self-calibration device for an electronic mutual inductor acquisition unit, such as Figure 1 As shown, it includes a selection switch, a conditioning circuit, an AD chip, a control chip and a DA chip;

[0046] The input end of the selection switch is connected to the first port of the DA chip, the output end of the selection switch is connected to the conditioning circuit, the output end of the conditioning circuit is connected to the first port of the AD chip, the second port of the AD chip is connected to the second port of the DA chip, the third port of the AD chip interacts with the first port of the control chip, the second port of the control chip is connected to the DA chip, and the third port of the control chip is connected to the selection switch.

[0047] Among them, the selection switch K is used to select the input of the conditioning circuit as UD Or U i ; The output voltage of the conditioning circuit is U M , AD chip collects U M The digital quantity obtained is D UM ;DA chip corresponds to digital quantity D DA The output voltage is U D , and output to the AD chip and conditioning circuit at the same time; finally, the calibration coefficient is calculated and the calibrated digital quantity U is output O .

[0048] Among them, the conditioning circuit is a linear system or a second-order system.

[0049] When the conditioning circuit is a linear system, the calculation method of the digital value of the transformer after calibration is as follows:

[0050]

[0051] Among them, k Am is the correction factor of the conditioning circuit, k Dm is the calibration coefficient of the DA chip, Db is the DC component of the system, k0 is the ratio of the rated analog quantity to the digital quantity, D M It is the digital quantity of the conditioning circuit.

[0052] When the conditioning circuit is a second-order system, the calculation method of the digital value of the transformer after calibration is as follows:

[0053]

[0054] Among them, k Dm is the calibration coefficient of the DA chip; Db is the DC component of the system; a and b are adjustment coefficients, according to the digital value D UM and digital quantity D DA Calculated; k0 is the ratio of rated analog quantity to digital quantity, D M It is the digital quantity of the conditioning circuit.

[0055] The present invention provides a calibration method for a self-calibration device of an electronic mutual inductor acquisition unit, comprising the following steps:

[0056] Step 1: Select the input of the conditioning circuit as the output U of the DA chip according to the selection switch. D Or regular input U i ;

[0057] Step 2, transmitting the output voltage of the conditioning circuit and the output voltage of the DA chip to the AD chip;

[0058] Step 3: Use the control chip to process the output voltage of the AD chip to obtain the calibration coefficient, and obtain the digital value of the calibrated transformer according to the correction coefficient.

[0059] The calibration coefficients obtained include the calibration coefficients of the DA chip and the correction coefficients of the conditioning circuit.

[0060] The calibration coefficient calculation method of the DA chip is as follows:

[0061]

[0062] Among them, D DAi is the digital quantity of DA chip, D UDi The digital quantity collected by the AD chip, k Di is the calibration coefficient of the DA chip output voltage, and the calibration coefficient k of the DA chip output voltage Di The average value is used to obtain the calibration coefficient k of the DA chip. Dm .

[0063] The correction factor of the conditioning circuit is calculated as follows:

[0064]

[0065] Among them, D DAi is the digital quantity of DA chip, D UMi is the digital quantity collected by the AD chip, Db is the DC component of the system, k Ai is the correction factor of the output voltage of the conditioning circuit, and the correction factor k of the output voltage of the conditioning circuit is Ai The average value is calculated to obtain the correction coefficient k of the conditioning circuit. Am .

[0066] When the conditioning circuit is a linear system, the calculation method of the digital value of the transformer after calibration is as follows:

[0067]

[0068] Among them, k Am is the correction factor of the conditioning circuit, k Dm is the calibration coefficient of the DA chip, Db is the DC component of the system, k0 is the ratio of the rated analog quantity to the digital quantity, D M It is the digital quantity of the conditioning circuit.

[0069] When the conditioning circuit is a second-order system, the calculation method of the digital value of the transformer after calibration is as follows:

[0070]

[0071] Among them, k Dm is the calibration coefficient of the DA chip; Db is the DC component of the system; a and b are adjustment coefficients, according to the digital value D UM and digital quantity D DA Calculated; k0 is the ratio of the rated analog quantity to the digital quantity, DM It is the digital quantity of the conditioning circuit.

[0072] The detailed steps of this calibration method are as follows:

[0073] Step 1: The controller controls the calibration time through the timer. When the calibration time is up, select the switch to select U D Input, DA chip digital quantity is 0 output voltage;

[0074] Step 2: At this time, the input of the conditioning circuit is actually 0V, and the value collected by the AD chip is the DC component Db of the system;

[0075] Step 3: Determine the type of collector. Different collectors have different ratios of rated analog and digital quantities k0:

[0076] Serial number Collector Type <![CDATA[Ratio k0 of rated analog quantity and digital quantity]]> 1 AC protection current 0.15V / 463 2 AC measurement current 1.5V / 11585 3 AC Voltage 1.5V / 11585 4 DC Current 5V / 15000 5 DC voltage 0.075V / 5000

[0077] Step 4: Calibrate the output voltage of the DA chip. The digital value of the DA chip is D DAi Output voltage U Di , the AD chip collects the digital quantity D UDi , the value of i is 0~N, at this time, the calibration coefficient k of the DA chip output voltage can be obtained Di :

[0078]

[0079] Calculate the calibration factor k Di The mean k Dm .

[0080] The specific implementation method is also relatively simple. The linear first-order system flow chart is as follows: Figure 2 shown.

[0081] Step 5: Calibrate the conditioning circuit. Assume that both the AD chip and the DA chip are bipolar 16-bit, and the reference voltage is 2.5V. As shown in the figure below, 5V corresponds to a digital value of 32768, and -5V corresponds to a digital value of -32768. The digital value of the DA chip is D DAi Output voltage U Di , the AD chip collects the digital quantity D UMi , the value of i is 0~N.

[0082]

[0083] (1) The conditioning circuit is a linear system;

[0084] U M =kU i +b

[0085] Where b has been obtained in step 2, and k can be obtained by the digital quantity D UM And the digital quantity is D DA The calculation results are:

[0086]

[0087] Calculate the calibration factor k Ai The mean k Am .

[0088] (2) The conditioning circuit is a second-order system;

[0089]

[0090] Among them, c has been obtained in step 2. Db, a and b can be obtained by digital quantity D UM And the digital quantity is D DA The calculation results are:

[0091]

[0092] Step 6. Control the selection switch to U i Input, calibrate the collected digital quantity through the above calibration coefficient, and output U O .

[0093] (1) The conditioning circuit is a linear system;

[0094]

[0095] (2) The conditioning circuit is a second-order system;

[0096]

[0097] The self-calibration device of an electronic mutual inductor acquisition unit proposed in the present invention has the following advantages:

[0098] 1) The circuit is simple and the amount of calculation is small. Add a selection switch and a DA chip to the acquisition circuit, and select the input of the conditioning circuit as the output U of the DA through the selection switch K. D Or regular input U i ; The output of the conditioning circuit is U M , AD chip collects U M The digital quantity obtained is D UM ;DA chip corresponds to digital quantity D DA The output voltage is U D , and output to the AD chip and conditioning circuit at the same time; finally, D UM and D DA Calculate the calibration coefficient and output the calibrated digital value U O ;

[0099] 2) It can be powered on for self-calibration, or scheduled for self-calibration, which saves time and effort, has high precision, does not require manual calibration, and does not have the subjective factors of manual calibration. Self-calibration can avoid the differences between the various components of the conditioning circuit, and each acquisition unit can be replaced without distinction; in addition, it can also solve the problem of accuracy changes caused by changes in the parameters of the acquisition unit components at different temperatures.

[0100] 3) The present invention can select different calibration formulas according to different conditioning circuits. The conditioning circuit can be a first-order system, a second-order system, or a higher-order system, and has strong applicability.

[0101] Key point: Add a selection switch and a DA chip to the acquisition circuit, and select the input of the conditioning circuit as the output U of the DA through the selection switch K. D Or regular input U i ; The output of the conditioning circuit is U M , AD chip collects U M The digital quantity obtained is D UM ;DA chip corresponds to digital quantity D DA The output voltage is U D , and output to the AD chip and conditioning circuit at the same time; finally, D UM and D DA Calculate the calibration coefficient and output the calibrated digital value U O This solution can realize offline and online self-calibration. If it is only used for offline self-calibration, the circuit can be simplified, such as Figure 3 This scheme is used to input U i When it is 0, the calibration coefficient is obtained in the offline state and saved in the memory for calculating the output calibrated digital quantity U in normal operation. O , the calculation method is the same as above.

[0102] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A self-calibration device for an electronic transformer acquisition unit, characterized in that: Including selection switch, conditioning circuit, AD chip, control chip and DA chip; The input end of the selection switch is connected to the first port of the DA chip, the output end of the selection switch is connected to the conditioning circuit, the output end of the conditioning circuit is connected to the first port of the AD chip, the second port of the AD chip is connected to the second port of the DA chip, the third port of the AD chip interacts with the first port of the control chip, the second port of the control chip is connected to the DA chip, and the third port of the control chip is connected to the selection switch.

2. The self-calibration device of the electronic mutual inductor acquisition unit according to claim 1, characterized in that: The conditioning circuit is a linear system or a second-order system.

3. The self-calibration device of the electronic mutual inductor acquisition unit according to claim 2, characterized in that: When the conditioning circuit is a linear system, the calculation method of the digital value of the transformer after calibration is as follows: Among them, k Am is the correction factor of the conditioning circuit, k Dm is the calibration coefficient of the DA chip, Db is the DC component of the system, k0 is the ratio of the rated analog quantity to the digital quantity, D M It is the digital quantity of the conditioning circuit.

4. The self-calibration device of the electronic mutual inductor acquisition unit according to claim 2, characterized in that: When the conditioning circuit is a second-order system, the calculation method of the digital value of the transformer after calibration is as follows: Among them, k Dm is the calibration coefficient of the DA chip; Db is the DC component of the system; a and b are adjustment coefficients, according to the digital value D UM And digital quantity D DA Calculated; k0 is the ratio of the rated analog quantity to the digital quantity, D M It is the digital quantity of the conditioning circuit.

5. A calibration method for a self-calibration device of an electronic mutual inductor acquisition unit, characterized in that: A self-calibration device for an electronic mutual inductor acquisition unit according to any one of claims 1 to 4, comprising: According to the selection switch, the input of the conditioning circuit is selected as the output U of the DA chip D Or regular input U i ; Transmit the output voltage of the conditioning circuit and the output voltage of the DA chip to the AD chip; The control chip is used to process the output voltage of the AD chip to obtain the calibration coefficient, and the digital value of the calibrated transformer is obtained according to the correction coefficient.

6. The calibration method of the self-calibration device of the electronic mutual inductor acquisition unit according to claim 5, characterized in that: The calibration coefficients obtained include the calibration coefficients of the DA chip and the correction coefficients of the conditioning circuit.

7. The calibration method of the self-calibration device of the electronic mutual inductor acquisition unit according to claim 6, characterized in that: The calibration coefficient calculation method of the DA chip is as follows: Among them, D DAi is the digital value of DA chip, D UDi The digital quantity collected by the AD chip, k Di is the calibration coefficient of the DA chip output voltage, and the calibration coefficient k of the DA chip output voltage Di The average value is used to obtain the calibration coefficient k of the DA chip. Dm .

8. The calibration method of the self-calibration device of the electronic mutual inductor acquisition unit according to claim 6, characterized in that: The correction factor of the conditioning circuit is calculated as follows: Among them, D DAi is the digital quantity of DA chip, D UMi is the digital quantity collected by the AD chip, Db is the DC component of the system, k Ai is the correction factor of the output voltage of the conditioning circuit, and the correction factor k of the output voltage of the conditioning circuit is Ai The average value is calculated to obtain the correction coefficient k of the conditioning circuit. Am .

9. The calibration method of the self-calibration device of the electronic mutual inductor acquisition unit according to claim 5, characterized in that: When the conditioning circuit is a linear system, the calculation method of the digital value of the transformer after calibration is as follows: Among them, k Am is the correction factor of the conditioning circuit, k Dm is the calibration coefficient of the DA chip, Db is the DC component of the system, k0 is the ratio of the rated analog quantity to the digital quantity, D M It is the digital quantity of the conditioning circuit.

10. The calibration method of the self-calibration device of the electronic mutual inductor acquisition unit according to claim 5, characterized in that: When the conditioning circuit is a second-order system, the calculation method of the digital value of the transformer after calibration is as follows: Among them, k Dm is the calibration coefficient of the DA chip; Db is the DC component of the system; a and b are adjustment coefficients, according to the digital value D UM and digital quantity D DA Calculated; k0 is the ratio of the rated analog quantity to the digital quantity, D M It is the digital quantity of the conditioning circuit.

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