Method for measuring error of a polyphase voltage transformer

Abstract

The present application relates to the technical field of mutual inductor error calibration, and provides a method for measuring the error of a multiple-ratio voltage mutual inductor. The primary sides of each basic-ratio standard voltage mutual inductor are connected in series and then connected in parallel with the primary side of the multiple-ratio voltage mutual inductor. The secondary sides of each basic-ratio standard voltage mutual inductor are respectively connected to the secondary side of the multiple-ratio voltage mutual inductor. An alternating voltage signal with a voltage equal to the rated primary voltage of the multiple-ratio voltage mutual inductor is input to both ends of the primary side of the multiple-ratio voltage mutual inductor and the series connection of the basic-ratio standard voltage mutual inductors. The secondary side difference voltage between the unconnected end of each basic-ratio standard voltage mutual inductor and the unconnected end of the multiple-ratio voltage mutual inductor is measured. The secondary side difference voltages are vector-added and averaged, and the average value is combined with the average value of the basic error of each basic-ratio standard voltage mutual inductor to calculate the error of the multiple-ratio voltage mutual inductor.

Description

Technical Field

[0001] This application relates to the field of transformer error verification technology. Specifically, it relates to a method for measuring the error of a multi-ratio voltage transformer. Background Technology

[0002] Instrument transformers (including voltage transformers and current transformers) are special-purpose transformers with two main uses: first, to extend the measuring range of AC electrical instruments; and second, to isolate high voltage and high current and convert them into low voltage and low current for use as signals in relay protection, automatic devices, and control circuits. In power systems, instrument transformers need to be calibrated or verified before leaving the factory and after a period of use. Traditional instrument transformer verification methods mostly employ the comparative differential measurement method. This involves connecting the secondary winding of the transformer under test to a load and comparing it with a standard instrument transformer of the same transformation ratio. A step-up transformer provides primary voltage (current) to both, and the differential voltage (differential current) signal between the two is input to an instrument transformer calibrator, which measures the error of the tested instrument transformer relative to the standard instrument transformer.

[0003] The comparative differential measurement method typically uses a standard voltage transformer as a standard to calibrate the voltage transformer under test. Although its principle is simple and operation is convenient, it requires a standard voltage transformer with an accuracy class two higher than the voltage transformer under test. This standard voltage transformer needs to be traced back to the metrological reference. Due to the limited number of metrological references and the high cost of maintaining them, calibrating and tracing the accuracy of high-accuracy standard voltage transformers is a very labor-intensive and costly task.

[0004] Furthermore, the accuracy of traditional instrument transformer calibrators has a decisive impact on whether the voltage transformer under test meets the required standards and the accuracy of electrical energy measurement. Currently, the measurement accuracy of instrument transformer calibrators that can be used for standard voltage transformer error calibration is generally lower than 0.02%, which cannot meet the traceability requirements of standard voltage transformers with an accuracy class of 0.02 or higher.

[0005] Therefore, there is an urgent need in this field to improve the comparative difference measurement method based on transformer calibrators in order to more accurately and efficiently complete the traceability of the values ​​of standard voltage transformers with high accuracy levels. Summary of the Invention

[0006] This application proposes a method for measuring the error of a multi-ratio voltage transformer.

[0007] According to the first aspect, the method for measuring the error of a multi-ratio voltage transformer proposed in this application includes the following steps: Step S1, obtaining k0 standard voltage transformers with a transformation ratio of 1:1 that have passed verification, where k0 is an integer and k0≥2; Step S2, obtaining a multi-ratio voltage transformer with a transformation ratio of k0:1, connecting the primary sides of each standard voltage transformer in series and then in parallel to the primary side of the multi-ratio voltage transformer; Step S3, constructing a measurement circuit using a voltage source device, a phase-locked loop amplifier differential measurement device, k0 standard voltage transformers, and the multi-ratio voltage transformer, short-circuiting the primary and secondary sides of each standard voltage transformer at the same-name terminals; Step S4, inputting an AC voltage signal, which is the rated primary voltage of the multi-ratio voltage transformer, to the primary side of the multi-ratio voltage transformer and the primary side of the k0 standard voltage transformers connected in series through the voltage source device, and comparing the AC voltage with the rated primary voltage of the multi-ratio voltage transformer. The voltage reference for the in-phase signal is set as the reference voltage. The basic error of each of the basic ratio standard voltage transformers is measured by a phase-locked loop amplification differential measurement device. Step S5: The short circuit between the primary and secondary terminals of each basic ratio standard voltage transformer is released, and the secondary terminals of each basic ratio standard voltage transformer are short-circuited with the secondary terminals of the multi-ratio voltage transformers respectively. Step S6: The secondary differential voltage between the unshort-circuited terminals of the secondary sides of each basic ratio standard voltage transformer and the unshort-circuited terminals of the secondary sides of the multi-ratio voltage transformers is measured by a phase-locked loop amplification differential measurement device. The secondary differential voltage is the vector difference between the secondary voltages of each basic ratio standard voltage transformer and the secondary voltages of the multi-ratio voltage transformers. Step S7: The vector sums of the secondary differential voltages measured by the phase-locked loop amplification differential measurement device are taken as the average value. Combined with the average value of the basic errors of each basic ratio standard voltage transformer, the error of the multi-ratio voltage transformer under the rated primary voltage is calculated.

[0008] According to the second aspect, the method for measuring the error of a multi-ratio voltage transformer proposed in this application includes the following steps:

[0009] Step S101: Obtain k2 standard voltage transformers with a base ratio of k1:1 that have passed inspection, and obtain the basic error of each of the standard voltage transformers with a base ratio under the rated primary voltage; where k2 is an integer and k2≥2;

[0010] Step S102: Connect the primary sides of each basic standard voltage transformer in series and then in parallel to form a transformation ratio of k2. k1:1 is the primary side of the multi-ratio voltage transformer, and the secondary side of each basic ratio standard voltage transformer is short-circuited to the secondary side of the multi-ratio voltage transformer with the same name terminal.

[0011] Step S103: A measurement circuit is constructed using a voltage source device, a phase-locked amplification differential measurement device, k2 basic ratio standard voltage transformers and multiple ratio voltage transformers. An AC voltage signal, which is the rated primary voltage of the multiple ratio voltage transformer, is input to the primary side of the multiple ratio voltage transformer and the two ends of the primary side of the k2 basic ratio standard voltage transformers connected in series through the voltage source device.

[0012] Step S104: Set the voltage reference in phase with the AC voltage signal as the reference voltage, and measure the secondary differential voltage between the unshort-circuited secondary side of each basic ratio standard voltage transformer and the unshort-circuited secondary side of the multiple ratio voltage transformer using a phase-locked amplification differential measurement device. The secondary differential voltage is the vector difference between the secondary side voltage of each basic ratio standard voltage transformer and the secondary side voltage of the multiple ratio voltage transformer.

[0013] Step S105: The average value of the vector summation of the secondary differential pressures measured by the phase-locked amplification differential measurement device is obtained. Combined with the average value of the basic error of each standard voltage transformer with a base ratio under the rated primary voltage, the error of the multi-ratio voltage transformer under the rated primary voltage is calculated.

[0014] According to a preferred embodiment of this application, the voltage resolution of the lock-in amplifier differential measurement device is at least 10nV.

[0015] According to a preferred embodiment of this application, the accuracy class of the base ratio standard voltage transformer is at least 0.1.

[0016] According to a preferred embodiment of this application, the accuracy level of the standard voltage transformer with a base ratio reaches 0.0001 or higher.

[0017] According to a preferred embodiment of this application, the same-named short circuit is configured as a high-side short circuit.

[0018] According to a preferred embodiment of the second aspect of this application, the ratio coefficient k1 of the base ratio standard voltage transformer is an integer greater than or equal to 2.

[0019] The method provided in this application can produce the following beneficial effects: Based on the basic principle of the comparative difference measurement method, the phase-locked amplification difference measurement device with a voltage resolution of at least 10nV can achieve accurate measurement of small voltage signals, while having good frequency response characteristics and good measurement stability; the improved comparative difference measurement method can conveniently extend the measurement of the error of the corresponding multiple ratio voltage transformer based on the basic error of multiple base ratio standard voltage transformers that have been traced in terms of measurement value. Therefore, with the help of the base ratio standard voltage transformer, error measurement and measurement value traceability of multiple ratio voltage transformers can be performed without the need for high accuracy level multiple ratio voltage transformers, which can greatly save manpower and cost for measurement value traceability of multiple ratio voltage transformers. Attached Figure Description

[0020] One or more embodiments of this application are illustrated by way of example with the corresponding accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are represented as similar elements. Unless otherwise stated, the figures in the drawings do not constitute a limitation on scale.

[0021] Figure 1 This is a schematic diagram of the self-test circuit of a standard voltage transformer with a base ratio of 1:1 used in one embodiment.

[0022] Figure 2 This is a schematic diagram of the error measurement circuit for a multi-ratio voltage transformer used in one embodiment when the corresponding terminals of the base ratio standard voltage transformer are short-circuited.

[0023] Figure 3 This is a schematic diagram of the error measurement circuit for a multi-ratio voltage transformer used in one embodiment, when the corresponding terminal of the base ratio standard voltage transformer is un-short-circuited and then short-circuited to the corresponding terminal of the secondary side of the multi-ratio voltage transformer.

[0024] Figure 4 This is a composite error vector diagram showing the measurement of the error of a multi-fold voltage transformer with a 2:1 ratio based on a standard voltage transformer with a base ratio of 1:1 in one embodiment.

[0025] Figure 5 This is a flowchart of a method for measuring the error of a multi-ratio voltage transformer based on a standard voltage transformer with a base ratio of 1:1, as described in one embodiment.

[0026] Figure 6 This is a schematic diagram of an error measurement circuit for a multi-ratio voltage transformer used in another embodiment.

[0027] Figure 7 A flowchart of a method for measuring the error of a multi-ratio voltage transformer, as described in another embodiment. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0029] It should be noted that, unless otherwise specified, the various features in the embodiments of this application can be combined with each other, all of which are within the protection scope of this application. Furthermore, although functional modules are divided in the schematic diagrams and a logical order is shown in the flowcharts, in some cases, the steps shown or described may be performed in a different module division or in a different order than that shown in the schematic diagrams or the flowcharts.

[0030] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. The term "and / or" as used in this specification includes any and all combinations of one or more of the associated listed items.

[0031] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings, so that the purpose and advantages of this application will be more clearly understood. Obviously, the described embodiments are some, but not all, of the embodiments of this application.

[0032] refer to Figure 1 This diagram shows the self-test circuit of a standard voltage transformer with a base ratio of 1:1. The standard voltage source AC and the error measuring device are connected to the primary side high-side A and primary side low-side B of the standard voltage transformer, respectively. The secondary side high-side a and secondary side low-side b of the standard voltage transformer are connected to the rated secondary load Y. In practice, a high-precision phase-locked loop amplification differential measurement device can be selected as the error measuring device. Since the base ratio of the standard voltage transformer is 1:1, after short-circuiting the corresponding terminals on the primary and secondary sides, the voltage difference between the un-short-circuited terminals on the primary and secondary sides can be measured using the error measuring device based on the differential measurement principle. Figure 1 In the embodiment shown, the corresponding terminals of the primary and secondary sides of the standard voltage transformer with the base ratio are short-circuited, configured to short-circuit the primary high-side A and the secondary high-side a. The standard voltage source AC outputs a voltage signal with an effective value equal to its rated voltage 1V to the primary high-side A and primary low-side B of the standard voltage transformer with the base ratio. This voltage signal is set as the reference voltage U of the error measuring device. Then, the voltage difference ΔU between the primary low-side B and the secondary low-side b can be measured by the error measuring device, thereby obtaining the basic error of the standard voltage transformer with the base ratio of 1:1 under the rated primary voltage.

[0033] The basic principle of this invention is as follows: Given the basic error of a standard voltage transformer with a base ratio, an AC voltage signal can be simultaneously input to the primary side of multiple series-connected standard voltage transformers and the primary side of corresponding multi-ratio voltage transformers connected in parallel using a voltage source device. The effective value of the AC voltage signal is equal to the rated primary voltage of the multi-ratio voltage transformer. After short-circuiting the secondary side of each standard voltage transformer with the corresponding terminal of the secondary side of the multi-ratio voltage transformer, since the input voltages of both the standard and multi-ratio voltage transformers are near the rated primary voltage, the secondary differential voltage between the un-short-circuited terminals of the standard and multi-ratio voltage transformers, measured by a high-precision phase-locked loop amplification differential measurement device, can be used to characterize the basic error of the multi-ratio voltage transformer under the rated primary voltage. Therefore, based on the basic errors of multiple standard voltage transformers with traceable measurement values, the error of the corresponding multi-ratio voltage transformer can be conveniently extended for measurement.

[0034] Specifically, Figure 2 and Figure 3 A schematic diagram of a multi-ratio voltage transformer error measurement circuit according to an embodiment of this application is shown. Figure 2 and Figure 3 In the illustrated embodiment, the base ratio standard voltage transformers all have a 1:1 ratio and equal rated primary voltages. The primary side terminals are labeled A1, B1, A2, B2…A… k0 B k0 (k0 is an integer and k0≥2), the terminals on the secondary side are labeled as a1, b1, a2, b2…a k0 b k0 The ratio of the multi-ratio voltage transformer is k0:1, and the rated primary voltage is k0 times the rated primary voltage of the standard voltage transformer with the base ratio. The terminals on the primary side are marked as C1 and D1, and the terminals on the secondary side are marked as c1 and d1, respectively.

[0035] like Figure 2 As shown, according to the concept of the present invention, the primary sides of k0 calibrated standard voltage transformers with a base ratio are connected in series, and then the series-connected primary sides are connected in parallel with the primary sides of a multiple voltage transformer with a ratio of k0:1. A measurement circuit is constructed using a voltage source device AC, a phase-locked loop amplifier differential measurement device, and the k0 standard voltage transformers with a base ratio and the multiple voltage transformer with a ratio of k0:1. For each standard voltage transformer with a base ratio, the primary and secondary sides are short-circuited at the same-name terminals. Figure 2(As shown in the diagram, this is a high-side short circuit). The secondary side can be connected to the corresponding rated secondary load. An AC voltage signal, representing the rated primary voltage of the multi-ratio voltage transformer, is input to the primary side of the multi-ratio voltage transformer with a transformation ratio of k0:1 and the primary side of the series connection of k0 basic ratio standard voltage transformers via a voltage source device. A voltage reference in phase with this AC voltage signal is set as the reference voltage U of the phase-locked loop amplification differential measurement device. ref The differential pressure signals ΔU1, ΔU2…ΔU1 between the primary and secondary un-short-circuited terminals of each base ratio standard voltage transformer are measured by a phase-locked loop amplifier differential measurement device. k0 This allows us to determine the basic error of each of the standard voltage transformers with different base ratios.

[0036] Furthermore, such as Figure 3 As shown, disconnect the corresponding terminals of the primary and secondary sides of each basic standard voltage transformer, and then short-circuit the secondary sides of each basic standard voltage transformer with the same terminal to the secondary sides of the voltage transformer with a ratio of k0:1. Figure 3 (As shown in the diagram, this is a high-side short circuit). The secondary side can be connected to the corresponding rated secondary loads. The secondary differential pressures ΔE1, ΔE2…ΔE are measured between the unshort-circuited terminals of the secondary sides of each standard voltage transformer with a base ratio and the unshort-circuited terminals of the secondary sides of a multi-ratio voltage transformer with a ratio of k0:1 using a phase-locked loop amplification differential measurement device. k0 By vector summing all secondary voltage differences and taking the average value, and combining this with the average value of the basic errors of standard voltage transformers with various base ratios, the error of a multi-ratio voltage transformer with a ratio of k0:1 under rated primary voltage can be calculated. To enable those skilled in the art to better understand the concept of this invention, the following references... Figure 4 An error composite vector diagram is generated based on the measurement error of a multi-ratio voltage transformer with a 2:1 ratio using a standard voltage transformer with a base ratio of 1:1. Figure 2 , Figure 3 This paper describes a method for measuring the error of a multi-fold voltage transformer with a 2:1 ratio based on a standard voltage transformer with a basic ratio of 1:1.

[0037] exist Figure 4 In the vector diagram shown, a two-dimensional coordinate system is created using the rated primary voltage of 2V of a voltage transformer with a transformation ratio of 2:1 as the zero-phase reference. Figure 4 The meanings of each vector are explained below:

[0038] The primary voltage vector of a standard voltage transformer with a first base ratio of 1:1;

[0039] The primary voltage vector of a standard voltage transformer with a second base ratio of 1:1;

[0040] The primary voltage vector of a multi-ratio voltage transformer with a transformation ratio of 2:1 is 2V;

[0041] The secondary voltage vector of a standard voltage transformer with a first base ratio of 1:1;

[0042] The secondary voltage vector of a standard voltage transformer with a second base ratio of 1:1;

[0043] The secondary voltage vector of a voltage transformer with a multiple transformation ratio of 2:1;

[0044] The fundamental error vector of a standard voltage transformer with a first base ratio of 1:1 can be obtained through... Figure 2 The measurement circuit shown measures the following:

[0045] The fundamental error vector of a standard voltage transformer with a second base ratio of 1:1 can be obtained through... Figure 2 The measurement circuit shown measures the following:

[0046] The secondary differential voltage vector between a 2:1 multiple ratio voltage transformer and a 1:1 first base ratio standard voltage transformer can be obtained through... Figure 3 The measurement circuit shown measures the following:

[0047] The secondary differential voltage vector between a 2:1 multiple ratio voltage transformer and a 1:1 first base ratio standard voltage transformer can be obtained through... Figure 3 The measurement circuit shown measures the following:

[0048] for and The vector sum;

[0049] for and The vector sum;

[0050] This is the error vector of a multi-ratio voltage transformer with a transformation ratio of 2:1.

[0051] according to Figure 4 The following derivation process can be derived from the vector diagram shown:

[0052] according to = - ; = - ; = - ; = - It can be concluded that:

[0053] = + = - ;

[0054] = + = - ;

[0055] Given + = =2, therefore:

[0056] = -1=( + ) / 2=( + + + ) / 2, which is related to Figure 4 The error vector of the multi-ratio voltage transformer shown is Totally consistent.

[0057] For standard voltage transformers with the above basic transformation ratio and voltage transformers with the above multiple transformation ratio for other rated voltages, please refer to the above reference. Figure 4 To understand the vector diagram for error compensation, we can ultimately arrive at the following formula:

[0058] = ( + + + ) / 2,

[0059] Furthermore, it extends to Figure 2 and Figure 3 The error measurement of the multi-ratio voltage transformer shown is combined with Figure 5 The flowchart shown provides a better understanding of the method for measuring the error of multi-ratio voltage transformers based on a standard voltage transformer with a base ratio of 1:1. For example... Figure 5 As shown, the error measurement method includes the following steps: Step S1, obtain k0 standard voltage transformers with a transformation ratio of 1:1 that have passed verification, where k0 is an integer and k0≥2; Step S2, obtain multiple voltage transformers with a transformation ratio of k0:1, connect the primary sides of each standard voltage transformer in series and then connect them in parallel to the primary side of the multiple voltage transformer; Step S3, construct a measurement circuit using a voltage source device, a phase-locked loop amplifier differential measurement device, k0 standard voltage transformers, and multiple voltage transformers, and short-circuit the primary and secondary sides of each standard voltage transformer to the same-name terminals; Step S4, input an AC voltage signal, which is the rated primary voltage of the multiple voltage transformer, to the primary side of the multiple voltage transformer and the primary side of the k0 standard voltage transformers connected in series through the voltage source device, and set the voltage reference in phase with the AC voltage signal. Using the reference voltage, the basic error of each of the standard voltage transformers with each base ratio is measured using a phase-locked loop amplification differential measurement device; Step S5, the short circuit between the primary and secondary sides of each standard voltage transformer with the same name is released, and the secondary side of each standard voltage transformer with the same name is short-circuited with the secondary side of the multi-ratio voltage transformer respectively; Step S6, the secondary differential voltage between the unshort-circuited secondary side of each standard voltage transformer with the unshort-circuited secondary side of the multi-ratio voltage transformer is measured using a phase-locked loop amplification differential measurement device. The secondary differential voltage is the vector difference between the secondary side voltage of each standard voltage transformer with the secondary side voltage of the multi-ratio voltage transformer; Step S7, the vector sum of the secondary differential voltages measured by the phase-locked loop amplification differential measurement device is taken as the average value, and combined with the average value of the basic errors of each standard voltage transformer with the base ratio, the error of the multi-ratio voltage transformer under the rated primary voltage is calculated.

[0060] In step S4, the basic error of each standard voltage transformer with a base ratio, measured by the phase-locked amplification differential measurement device, is expressed by the following formula:

[0061] ε1(m) = f1(m) +j δ1(m) Formula (1)

[0062] In the above formula (1), ε1(m) represents the basic error of the m-th basic ratio standard voltage transformer, f1(m) represents the ratio difference component of the m-th basic ratio standard voltage transformer, δ1(m) represents the angle difference component of the m-th basic ratio standard voltage transformer, j represents the imaginary unit, where m is an integer and 1≤m≤k0.

[0063] In step S6, the secondary differential voltage between the unshort-circuited secondary side of each basic ratio standard voltage transformer and the unshort-circuited secondary side of the multiple ratio voltage transformer, measured by the phase-locked amplification differential measurement device, is expressed by the following formula:

[0064] u1(n) = ɑ1(n) +j Formula (2) for β1(n)

[0065] In the above formula (2), u1(n) represents the secondary differential voltage between the unshort-circuited secondary side of the nth basic ratio standard voltage transformer and the unshort-circuited secondary side of the multiple ratio voltage transformer, ɑ1(n) represents the ratio component of the secondary differential voltage, and β1(n) represents the angle component of the secondary differential voltage, where n is an integer and 1≤n≤k0.

[0066] Since the sum of the primary voltage vectors of the k0 basic ratio standard voltage transformers is equal to the primary voltage vector of the multiple ratio voltage transformer, in step S7, the error of the multiple ratio voltage transformer is obtained by the following formula:

[0067]

[0068] In the above formula (3), ε2(x) represents the error of a multi-ratio voltage transformer with a ratio of k0:1 under the rated primary voltage, f2(x) represents the ratio difference component of a multi-ratio voltage transformer with a ratio of k0:1 under the rated primary voltage, and δ2(x) represents the angle difference component of a multi-ratio voltage transformer with a ratio of k0:1 under the rated primary voltage.

[0069] Wherein, f2(x) is derived from the following formula:

[0070]

[0071] The f2(x) calculated by the above formula (4) is used to verify whether the ratio difference of a multi-ratio voltage transformer with a ratio of k0:1 is less than the error limit specified in the verification procedure.

[0072] δ²(x) is derived from the following formula:

[0073]

[0074] The δ2(x) calculated by the above formula (5) is used to verify whether the angle difference of a multi-ratio voltage transformer with a transformation ratio of k0:1 is less than the error limit specified in the verification procedure.

[0075] Figure 6 A schematic diagram of a multi-ratio voltage transformer error measurement circuit according to another embodiment of this application is shown. Figure 6In the illustrated embodiment, the basic ratio standard voltage transformers all have a transformation ratio of k1:1 and equal rated primary voltages. The primary side terminals are labeled M1, N1, M2, N2…M k2 N k2 (k2 is an integer and k2≥2), the terminals on the secondary side are labeled as m1, n1, m2, n2…m k2 n k2 The transformation ratio of the multi-ratio voltage transformer is k2. k1:1 and the rated primary voltage is correspondingly k2 times the rated primary voltage of the base ratio standard voltage transformer with a transformation ratio of k1:1. The primary side terminals of the multi-ratio voltage transformer are marked as P1 and Q1, and the secondary side terminals are marked as p1 and q1, respectively. For example Figure 6 As shown, according to the concept of the present invention, the primary sides of k2 calibrated standard voltage transformers with base ratios are connected in series and then connected to a transformer with a ratio of k2. The primary side of a k1:1 multi-ratio voltage transformer is connected in parallel, utilizing an AC voltage source device, a phase-locked loop amplifier differential measurement device, and k2 standard voltage transformers with a k1:1 ratio, and a k2-ratio transformer. A measurement circuit is constructed using a k1:1 multi-ratio voltage transformer. The secondary sides of each basic ratio standard voltage transformer are short-circuited with the secondary sides of the multi-ratio voltage transformer using the same-name terminals. Figure 6 (As shown in the diagram, high-side short-circuit) The secondary side can be connected to the corresponding rated secondary loads respectively. An AC voltage signal, representing the rated primary voltage of the multi-ratio voltage transformer, is input to the primary side of the multi-ratio voltage transformer and the primary side of the k2 series-connected standard voltage transformers via a voltage source device AC. The voltage reference in phase with this AC voltage signal is set as the reference voltage U of the phase-locked loop amplification differential measurement device. ref The secondary differential pressures ΔE1, ΔE2…ΔE, measured by a phase-locked loop amplification differential measurement device, are the voltages between the unshort-circuited secondary terminals of each basic ratio standard voltage transformer and the unshort-circuited secondary terminals of the multiple ratio voltage transformer. k0 After vector summation and averaging, combined with the average of the basic errors of standard voltage transformers with various base ratios, the ratio k2 can be calculated. The error of a k1:1 multi-ratio voltage transformer under rated primary voltage.

[0076] Combination Figure 7 The flowchart shown provides a better understanding of measuring a standard voltage transformer with a base ratio of k1:1 and a base ratio of k2. Methods for measuring the error of multi-ratio voltage transformers with k1:1. For example... Figure 7As shown, the error measurement method includes the following steps: Step S101, obtain k2 qualified standard voltage transformers with a transformation ratio of k1:1, and obtain the basic error of each of the standard voltage transformers under the rated primary voltage, where k2 is an integer and k2≥2; Step S102, connect the primary sides of each standard voltage transformer in series and then in parallel to form a transformation ratio of k2. In step S103, a measurement circuit is constructed using a voltage source device, a phase-locked amplification differential measurement device, k2 basic ratio standard voltage transformers, and the multiple ratio voltage transformer. The voltage source device inputs an AC voltage signal equal to the rated primary voltage of the multiple ratio voltage transformer to the primary side of the multiple ratio voltage transformer and the primary side of the k2 basic ratio standard voltage transformers connected in series. In step S104, a voltage reference in phase with the AC voltage signal is set as the reference voltage, and differential measurement is performed using a phase-locked amplification differential measurement device. The device measures the secondary differential voltage between the unshort-circuited secondary side of each standard voltage transformer with a base ratio and the unshort-circuited secondary side of the multi-ratio voltage transformer. The secondary differential voltage is the vector difference between the secondary voltages of each standard voltage transformer with a base ratio and the secondary voltages of the multi-ratio voltage transformer. In step S105, the secondary differential voltages measured by the phase-locked amplification differential measurement device are vector-summed and averaged. Combined with the average value of the basic errors of each standard voltage transformer with a base ratio under rated primary voltage, the error of the multi-ratio voltage transformer under rated primary voltage is calculated. In step S101, the basic error of the standard voltage transformer with a base ratio is expressed by the following formula:

[0077] ε2(m) = f2(m) +j δ2(m) Formula (6)

[0078] In the above formula (6), ε2(m) represents the basic error of the m-th basic ratio standard voltage transformer with a ratio of k1:1, f2(m) represents the ratio difference component of the m-th basic ratio standard voltage transformer with a ratio of k1:1, δ2(m) represents the angle difference component of the m-th basic ratio standard voltage transformer with a ratio of k1:1, j represents the imaginary unit, where m is an integer and 1≤m≤k2;

[0079] In step S104, the secondary differential voltage between the unshort-circuited secondary side of each basic ratio standard voltage transformer and the unshort-circuited secondary side of the multiple ratio voltage transformer, measured by the phase-locked amplification differential measurement device, is expressed by the following formula:

[0080] u2(n) = ɑ2(n) +j Formula (7) for β2(n)

[0081] In the above formula (7), u2(n) represents the non-short-circuited secondary side of the nth basic ratio standard voltage transformer with a transformation ratio of k1:1 and the transformation ratio of k2. k1: The secondary differential voltage between the unshort-circuited terminals of the secondary side of a multi-ratio voltage transformer with a ratio of 1, α2(n) represents the ratio component of the secondary differential voltage, β2(n) represents the angle component of the secondary differential voltage, where n is an integer and 1≤n≤k2;

[0082] In step S105, the error of the multi-ratio voltage transformer is expressed by the following formula:

[0083] ε2(y) = f2(y) +j δ2(y) Formula (8)

[0084] In the above formula (8), ε2(y) represents the ratio k2 k1: The error of a multi-ratio voltage transformer at rated primary voltage, where k1 is the ratio of k2. k1: The ratio difference component of a multi-ratio voltage transformer at rated primary voltage, where k1 is a multiple of k2. δ2(y) represents the ratio difference component of a multi-ratio voltage transformer at k2. k1: The angle difference component of a multi-ratio voltage transformer under rated primary voltage;

[0085] Wherein, f2(y) is derived from the following formula:

[0086]

[0087] The f2(y) calculated using the above formula (9) is used to verify the transformation ratio k2. Whether the ratio difference of a k1:1 multi-ratio voltage transformer under rated primary voltage is less than the error limit specified in the verification procedure;

[0088] δ2(y) is derived from the following formula:

[0089]

[0090] The δ2(y) calculated using the above formula (10) is used to verify the transformation ratio k2. Whether the phase angle difference of a k1:1 multi-ratio voltage transformer under rated primary voltage is less than the error limit specified in the verification procedure.

[0091] According to embodiments of this application, the voltage resolution of the lock-in amplifier differential measurement device is at least 10nV, thus enabling accurate measurement of 10 -8The accuracy class is extremely small. Preferably, the accuracy class of the standard voltage transformer with the base ratio is at least 0.1. Particularly preferably, the accuracy class of the standard voltage transformer with the base ratio is 0.0001 or higher.

[0092] According to embodiments of this application, when the transformation ratio coefficient of the standard voltage transformer with the base transformation ratio is an integer greater than or equal to 2, it is possible to first adopt... Figure 5 The method shown yields the error of a voltage transformer with a certain intermediate integer multiple transformation ratio. Then, it uses... Figure 7 The illustrated method extends the calculation to obtain the error of the final multi-ratio voltage transformer. This reduces the accumulated error and ensures the accuracy level of the final multi-ratio voltage transformer's traceability. For example, the ratio of the base ratio standard voltage transformer can be selected as a prime number within 100, which can be achieved by first using... Figure 5 The method shown is based on measuring the error of a standard voltage transformer with a base ratio of 1:1, and then using... Figure 7 The illustrated method flow extends to obtain the error of the final multi-ratio voltage transformer. For example, the error of a 2:1 basic ratio standard voltage transformer can be measured based on two 1:1 basic ratio standard voltage transformers. Then, the error of a 10:1 basic ratio standard voltage transformer can be measured based on five 2:1 basic ratio standard voltage transformers. Subsequently, the error of a 100:1 basic ratio standard voltage transformer can be measured based on ten 10:1 basic ratio standard voltage transformers, and the error of a 1000:1 basic ratio standard voltage transformer can be measured based on ten 100:1 basic ratio standard voltage transformers. The above-mentioned basic ratio standard voltage transformers are merely illustrative and not limiting. Other feasible methods for expanding the transformer ratio include, but are not limited to: measuring the error of a standard voltage transformer with a 5:1 ratio based on five standard voltage transformers with a 1:1 ratio; then measuring the error of a standard voltage transformer with a 25:1 ratio based on five standard voltage transformers with a 5:1 ratio; then measuring the error of a standard voltage transformer with a 125:1 ratio based on five standard voltage transformers with a 25:1 ratio; and measuring the error of a standard voltage transformer with a 1000:1 ratio based on eight standard voltage transformers with a 125:1 ratio.

[0093] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a readable storage medium of a non-volatile computer, and when executed, it can include the processes of the embodiments of the methods described above. Any references to memory, storage, databases, or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), RAMbus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and RAMbus dynamic RAM (RDRAM), etc.

[0094] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0095] It should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them; under the concept of this application, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of this application as described above. For the sake of brevity, they are not provided in detail; although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application. For those skilled in the art, several modifications and improvements can be made without departing from the concept of this application, and these all fall within the protection scope of this application.

Claims

1. A method for measuring the error of a multi-ratio voltage transformer, characterized in that, The method includes: Step S1: Obtain k0 standard voltage transformers with a basic transformation ratio of 1:1 that have passed the inspection, where k0 is an integer and k0≥2; Step S2: Obtain a multi-ratio voltage transformer with a transformation ratio of k0:1, and connect the primary side of each of the basic ratio standard voltage transformers in series and then in parallel to the primary side of the multi-ratio voltage transformer. Step S3: Construct a measurement circuit using a voltage source device, a phase-locked amplification differential measurement device, k0 of the basic ratio standard voltage transformers and the multiple ratio voltage transformers, and short-circuit the primary and secondary sides of each of the basic ratio standard voltage transformers with the same name. Step S4: Input an AC voltage signal, which is the rated primary voltage of the multiple ratio voltage transformer, to the primary side of the multiple ratio voltage transformer and the primary side of the k0 basic ratio standard voltage transformers connected in series through the voltage source device; set the voltage reference in phase with the AC voltage signal as the reference voltage; and measure the basic error of each of the basic ratio standard voltage transformers through the phase-locked amplification differential measurement device. Step S5: Unconnect the corresponding terminals of the primary and secondary sides of each of the basic ratio standard voltage transformers, and short-circuit the corresponding terminals of the secondary sides of each of the basic ratio standard voltage transformers with the secondary sides of the multiple ratio voltage transformers respectively. Step S6: Measure the secondary differential voltage between the unshort-circuited secondary side of each of the basic ratio standard voltage transformers and the unshort-circuited secondary side of the multiple ratio voltage transformer using the phase-locked amplification differential measurement device. The secondary differential voltage is the vector difference between the secondary side voltage of each of the basic ratio standard voltage transformers and the secondary side voltage of the multiple ratio voltage transformer. Step S7: The average value of the vector summation of the secondary differential pressures measured by the phase-locked amplification differential measurement device is obtained. Combined with the average value of the basic errors of the standard voltage transformers of the basic ratio, the error of the multiple ratio voltage transformer under the rated primary voltage is calculated.

2. The method according to claim 1, characterized in that, In step S4, the fundamental error of each of the basic ratio standard voltage transformers measured by the phase-locked amplification differential measurement device is expressed by the following formula: ε1(m) = f1(m) +j δ1(m) Formula (1) In the above formula (1), ε1(m) represents the basic error of the m-th basic ratio standard voltage transformer, f1(m) represents the ratio difference component of the m-th basic ratio standard voltage transformer, δ1(m) represents the angle difference component of the m-th basic ratio standard voltage transformer, j represents the imaginary unit, where m is an integer and 1≤m≤k0; In step S6, the secondary differential voltage between the unshort-circuited secondary side of each of the basic ratio standard voltage transformers and the unshort-circuited secondary side of the multiple ratio voltage transformers, measured by the phase-locked amplification differential measurement device, is expressed by the following formula: u1(n) = ɑ1(n) +j β1(n) Formula (2) In the above formula (2), u1(n) represents the secondary differential voltage between the unshort-circuited secondary side of the nth basic ratio standard voltage transformer and the unshort-circuited secondary side of the multiple ratio voltage transformer, ɑ1(n) represents the ratio component of the secondary differential voltage, and β1(n) represents the angle component of the secondary differential voltage, where n is an integer and 1≤n≤k0; In step S7, the error of the multi-ratio voltage transformer is derived from the following formula: In the above formula (3), ε2(x) represents the error of the multiple ratio voltage transformer with a transformation ratio of k0:1 under the rated primary voltage, f2(x) represents the ratio difference component of the multiple ratio voltage transformer with a transformation ratio of k0:1 under the rated primary voltage, and δ2(x) represents the angle difference component of the multiple ratio voltage transformer with a transformation ratio of k0:1 under the rated primary voltage; Wherein, f2(x) is derived from the following formula: The f2(x) calculated by the above formula (4) is used to verify whether the ratio difference of the multiple ratio voltage transformer with a ratio of k0:1 is less than the error limit specified in the verification procedure. δ²(x) is derived from the following formula: The δ2(x) calculated by the above formula (5) is used to verify whether the angle difference of the multi-ratio voltage transformer with a ratio of k0:1 is less than the error limit specified in the verification procedure.

3. The method according to claim 1, characterized in that, The voltage resolution of the lock-in amplifier differential measurement device is at least 10nV.

4. The method according to claim 1, characterized in that, The accuracy level of the standard voltage transformer with the basic ratio reaches 0.0001 or higher.

5. A method for measuring the error of a multi-ratio voltage transformer, characterized in that, The method includes: Step S101: Obtain k2 qualified standard voltage transformers with a transformation ratio of k1:1, and obtain the basic error of each of the standard voltage transformers with a transformation ratio under the rated primary voltage; where k2 is an integer and k2≥2; Step S102: Connect the primary sides of each of the basic ratio standard voltage transformers in series and then in parallel to form a transformation ratio of k2. k1:1 is the primary side of a multi-ratio voltage transformer, and the secondary side of each of the basic ratio standard voltage transformers is shorted to the secondary side of the multi-ratio voltage transformer with the same name terminal. Step S103: A measurement circuit is constructed using a voltage source device, a phase-locked loop amplifier differential measurement device, k2 of the basic ratio standard voltage transformers and the multiple ratio voltage transformers. An AC voltage signal, which is the rated primary voltage of the multiple ratio voltage transformer, is input to the primary side of the multiple ratio voltage transformer and the two ends of the primary side of the k2 basic ratio standard voltage transformers connected in series through the voltage source device. Step S104: Set the voltage reference in phase with the AC voltage signal as the reference voltage, and measure the secondary differential voltage between the unshort-circuited secondary side of each of the basic ratio standard voltage transformers and the unshort-circuited secondary side of the multiple ratio voltage transformers through the phase-locked amplification differential measurement device. The secondary differential voltage is the vector difference between the secondary side voltage of each of the basic ratio standard voltage transformers and the secondary side voltage of the multiple ratio voltage transformers. Step S105: The average value of the secondary differential pressures measured by the phase-locked amplification differential measurement device is obtained by vector summation. Combined with the average value of the basic error of each basic ratio standard voltage transformer under the rated primary voltage, the error of the multiple ratio voltage transformer under the rated primary voltage is calculated.

6. The method according to claim 5, characterized in that, In step S101, the basic error of the standard voltage transformer with the base ratio is expressed by the following formula: ε2(m) = f2(m) +j δ2(m) Formula (6) In the above formula (6), ε2(m) represents the basic error of the m-th base ratio standard voltage transformer with a ratio of k1:1, f2(m) represents the ratio difference component of the m-th base ratio standard voltage transformer with a ratio of k1:1, δ2(m) represents the angle difference component of the m-th base ratio standard voltage transformer with a ratio of k1:1, j represents the imaginary unit, where m is an integer and 1≤m≤k2; In step S104, the secondary differential voltage between the unshort-circuited secondary side of each of the basic ratio standard voltage transformers and the unshort-circuited secondary side of the multiple ratio voltage transformers, measured by the phase-locked amplification differential measurement device, is expressed by the following formula: u2(n) = ɑ2(n) +j Formula (7) for β2(n) In the above formula (7), u2(n) represents the non-short-circuited secondary side of the nth basic ratio standard voltage transformer with a transformation ratio of k1:1 and the transformation ratio of k2. k1: The secondary differential voltage between the unshort-circuited terminals of the secondary side of the multi-ratio voltage transformer, α2(n) represents the ratio component of the secondary differential voltage, β2(n) represents the angle component of the secondary differential voltage, where n is an integer and 1≤n≤k2; In step S105, the error of the multi-ratio voltage transformer is expressed by the following formula: ε2(y) = f2(y) +j δ2(y), Equation (8) In the above formula (8), ε2(y) represents the ratio k2 k1:1 represents the error of the multi-ratio voltage transformer under rated primary voltage, and f2(y) represents the ratio k2. k1:1 represents the ratio difference component of the multi-ratio voltage transformer under rated primary voltage, δ2(y) represents the ratio of k2. k1:1 is the angle difference component of the multi-ratio voltage transformer under the rated primary voltage; Wherein, f2(y) is derived from the following formula: The f2(y) calculated using the above formula (9) is used to verify the transformation ratio k2. Whether the ratio difference of the multi-ratio voltage transformer described in k1:1 under the rated primary voltage is less than the error limit specified in the verification procedure; δ2(y) is derived from the following formula: The δ2(y) calculated using the above formula (10) is used to verify the transformation ratio k2. Whether the phase angle difference of the multi-ratio voltage transformer k1:1 under the rated primary voltage is less than the error limit specified in the verification procedure.

7. The method according to claim 5, characterized in that, The voltage resolution of the lock-in amplifier differential measurement device is at least 10nV.

8. The method according to claim 5, characterized in that, The accuracy class of the standard voltage transformer with the basic transformation ratio shall be at least 0.

1.

9. The method according to claim 5, characterized in that, The accuracy level of the standard voltage transformer with the basic ratio reaches 0.0001 or higher.

10. The method according to claim 5, characterized in that, The transformation coefficient k1 of the basic transformation standard voltage transformer is an integer greater than or equal to 2.

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