A high-accuracy current ratio standard and implementation method thereof

Abstract

The present invention relates to a high-accuracy current ratio standard and an implementation method thereof. The standard comprises a main current transformer and a ratio difference compensation module and an angle difference compensation module connected thereto. The ratio difference compensation module is formed by connecting a compensation current transformer, a first standard resistor and a first precision adjustable resistor to form a four-terminal network. The angle difference compensation module is formed by connecting a hollow mutual inductance coil, a second standard resistor and a second precision adjustable resistor to form a four-terminal network. Two terminals on the input side of the ratio difference compensation module are respectively connected to the terminals on the primary side of the main current transformer and one terminal on the input side of the angle difference compensation module. Another terminal on the primary side of the main current transformer and another terminal on the input side of the angle difference compensation module form the input end of the current ratio standard. Two terminals on the output side of the ratio difference compensation module and two terminals on the output side of the angle difference compensation module are connected in parallel between the secondary side terminals of the main current transformer to form the output end of the current ratio standard.

Description

Technical Field

[0001] The present application relates to the technical field of electric power measurement standards, and more particularly to a high-accuracy current ratio standard and an implementation method thereof. Background Art

[0002] Current transformers are usually used to convert the large current on the primary side of the power grid into the small current on the secondary side. According to their use, current transformers can be divided into two categories: (1) current transformers for measurement, that is, when the power system is in stable operation, the high-voltage and large current on the primary side is converted into the low-voltage and small current on the secondary side, thereby completing the conversion of high-power measurement current to low-power measurement current, realizing online current monitoring, data storage, and electric energy measurement; (2) current transformers for protection, that is, when a fault occurs in the power grid, the control system starts the corresponding relay protection device, completes the equipment removal of the faulty electromagnetic device in the power system, and puts the backup electromagnetic device and other equipment into use to ensure the safe and stable operation of the power system.

[0003] The current transformers commonly used at present are mainly divided into electronic current transformers and electromagnetic current transformers. The latter has the advantages of simple principle and easy use, and is more widely used. For measuring current transformers, their accuracy is related to the accuracy of electric energy measurement. The accuracy of current transformers is generally determined by verification and calibration tests, usually by comparing the current transformer under test with a current ratio standard. The existing JJG 313-1010 regulations stipulate how to verify measuring current transformers, and the existing JJF 1701.1-1018 and JJF 1701.4-1019 technical specifications standardize the standard current transformers for measurement and the type evaluation outline of current transformers.

[0004] The current ratio standard needs to meet two conditions: stability and traceability. Although the current electromagnetic standard transformer has been widely used as a standard in the field of power metering, it still has defects. In particular, the accuracy of the electromagnetic current transformer is easily affected by conditions such as ambient temperature, humidity, and the spatial position of the core; on the other hand, the working conditions of the electromagnetic current transformer are very complex. For example, the proximity effect of the transformer and its surrounding electrical equipment will cause the error of the transformer to become larger, thereby reducing its accuracy. In addition, with the development of new power systems, the traceability demand for broadband current transformers is becoming more and more urgent.

[0005] Therefore, the art desires a method for conveniently implementing a high-accuracy current ratio standard, so that when the error of the current ratio standard exceeds a limit, the error of the current ratio standard can be compensated by convenient and effective means to achieve and maintain high accuracy. Summary of the invention

[0006] According to the first aspect of the present application, a high-accuracy current ratio standard is proposed, which includes a main current transformer with an accuracy of at least level 1, a ratio difference compensation module and an angle difference compensation module connected to the main current transformer, wherein the ratio difference compensation module is formed by connecting a compensating current transformer, a first standard resistor and a first precision adjustable resistor to form a four-terminal network, and the angle difference compensation module is formed by connecting a hollow mutual inductance coil, a second standard resistor and a second precision adjustable resistor to form a four-terminal network, two terminals on the input side of the ratio difference compensation module are respectively connected to the terminals on the primary side of the main current transformer and one terminal on the input side of the angle difference compensation module, and the other terminal on the primary side of the main current transformer and the other terminal on the input side of the angle difference compensation module form a current ratio. The input end of the standard, the two terminals on the output side of the ratio difference compensation module and the two terminals on the output side of the angle difference compensation module are all connected in parallel between the terminals on the secondary side of the main current transformer to form the output end of the current ratio standard, wherein the ratio difference compensation module is configured to compensate for the predetermined ratio difference compensation amount by adjusting the first precision adjustable resistor to the ratio difference of the current ratio standard based on a predetermined ratio difference compensation amount, so that the ratio difference of the current ratio standard is within the ratio difference limit range required by high accuracy, and the angle difference compensation module is configured to compensate for the predetermined angle difference compensation amount by adjusting the second precision adjustable resistor to the angular difference of the current ratio standard based on a predetermined angular difference compensation amount, so that the angular difference of the current ratio standard is within the angular difference limit range required by high accuracy.

[0007] According to a preferred embodiment of the first aspect of the present application, the transformation ratio of the compensating current transformer of the ratio difference compensation module, the resistance value of the first standard resistor, and the resistance value and adjustment range of the first precision adjustable resistor are configured according to the ratio difference, rated transformation ratio and rated secondary load of the main current transformer under rated operating conditions, and the number of turns and coil size of the hollow mutual inductance coil of the angle difference compensation module, the resistance value of the second standard resistor, and the resistance value and adjustment range of the second precision adjustable resistor are configured according to the angle difference, rated transformation ratio, rated secondary load of the main current transformer under rated operating conditions and the AC frequency of the rated operating conditions.

[0008] According to the second aspect of the present application, another high-accuracy current ratio standard is proposed, which includes a main current transformer and an auxiliary current transformer with an accuracy of at least level 1 and connected in series on the primary side, and a ratio difference compensation module and an angle difference compensation module connected to the main current transformer and the auxiliary current transformer, wherein the ratio difference compensation module is formed by connecting a compensation current transformer, a first standard resistor and a first precision adjustable resistor to form a four-terminal network, and the angle difference compensation module is formed by connecting a hollow mutual inductance coil, a second standard resistor and a second precision adjustable resistor to form a four-terminal network, the terminals on the primary side of the main current transformer and the auxiliary current transformer that are not connected in series form the input end of the current ratio standard, and the terminals on the input side of the ratio difference compensation module are connected in series with the terminals on the input side of the angle difference compensation module and are connected to the auxiliary Between the terminals on the secondary side of the current transformer, the two terminals on the output side of the ratio difference compensation module and the two terminals on the output side of the angle difference compensation module are connected in parallel between the terminals on the secondary side of the main current transformer to form the output end of the current ratio standard, wherein the ratio difference compensation module is configured to compensate for the predetermined ratio difference compensation amount by adjusting the ratio difference of the current ratio standard by the first precision adjustable resistor based on the predetermined ratio difference compensation amount, so that the ratio difference of the current ratio standard is within the ratio difference limit range required by high accuracy, and the angle difference compensation module is configured to compensate for the predetermined angle difference compensation amount by adjusting the angle difference of the current ratio standard by the second precision adjustable resistor based on the predetermined angle difference compensation amount, so that the angle difference of the current ratio standard is within the angle difference limit range required by high accuracy.

[0009] According to a preferred embodiment of the second aspect of the present application, the transformation ratio of the compensating current transformer of the ratio difference compensation module, the resistance value of the first standard resistor, and the resistance value and adjustment range of the first precision adjustable resistor are configured according to the ratio difference, rated transformation ratio, rated secondary load of the main current transformer under rated operating conditions and the current transformation ratio of the auxiliary current transformer, and the number of turns and coil size of the hollow mutual inductance coil of the angle difference compensation module, the resistance value of the second standard resistor, and the resistance value and adjustment range of the second precision adjustable resistor are configured according to the angle difference, rated transformation ratio, rated secondary load of the main current transformer under rated operating conditions, the AC frequency of the rated operating conditions and the current transformation ratio of the auxiliary current transformer.

[0010] According to a third aspect of the present application, a method for realizing a high-accuracy current ratio standard is proposed, and the method comprises the following steps: S1, obtaining an electromagnetic current transformer with an accuracy of at least level 1 and measuring its ratio difference and angle difference under rated conditions, wherein the electromagnetic current transformer is configured as a single main current transformer or a main current transformer and a secondary current transformer connected in series on the primary side; S2, calculating the ratio difference compensation amount and angle difference compensation amount to be applied to the main current transformer to realize a high-accuracy current ratio standard based on the ratio difference and angle difference of the current transformer; S3, calculating the ratio difference compensation amount and angle difference compensation amount to be applied to the main current transformer according to the ratio difference and angle difference of the main current transformer; The rated transformation ratio, rated secondary load and ratio difference compensation amount of the transformer configure the parameters of the ratio difference compensation module, and the parameters of the angle difference compensation module are configured according to the rated transformation ratio, rated secondary load, rated working condition AC frequency and angle difference compensation amount of the main current transformer. The ratio difference compensation module is connected by a compensating current transformer, a first standard resistor and a first precision adjustable resistor to form a four-terminal network, and the angle difference compensation module is connected by a hollow mutual inductance coil, a second standard resistor and a second precision adjustable resistor to form a four-terminal network. The parameters of the ratio difference compensation module include: the transformation ratio of the compensating current transformer, the first standard resistor and the second precision adjustable resistor. The parameters of the angle difference compensation module include: the number of turns and coil size of the hollow mutual inductance coil, the resistance of the second standard resistor, and the resistance and adjustment range of the second precision adjustable resistor; S4, connecting the ratio difference compensation module and the angle difference compensation module to the current transformer to form a current ratio standard; S5, measuring the ratio difference and angle difference of the current ratio standard under rated conditions, and verifying the level of the ratio difference and angle difference of the current ratio standard; S6, judging whether the ratio difference or angle difference of the current ratio standard exceeds If the error limit range required by high accuracy is not exceeded, the verification is passed and go to step S8, otherwise continue to step S7; S7, if the ratio difference of the current ratio standard exceeds the ratio difference limit range required by high accuracy, the ratio difference of the current ratio standard is compensated by adjusting the resistance value of the first precision adjustable resistor, if the angular difference of the current ratio standard exceeds the angular difference limit range required by high accuracy, the angular difference of the current ratio standard is compensated by adjusting the resistance value of the second precision adjustable resistor, and then go to step S5; S8, complete the realization of the high-accuracy current ratio standard.

[0011] According to a preferred embodiment of the third aspect of the present application, when the electromagnetic current transformer is configured as a single main current transformer, connecting the ratio difference compensation module and the angle difference compensation module to the current transformer includes: connecting the two terminals on the input side of the compensating current transformer to the terminals on the primary side of the main current transformer and one terminal on the input side of the angle difference compensation module, respectively, so that the other terminal on the primary side of the main current transformer and the other terminal on the input side of the angle difference compensation module form the input end of the current ratio standard, and the two terminals on the output side of the ratio difference compensation module and the two terminals on the output side of the angle difference compensation module are connected in parallel between the terminals on the secondary side of the main current transformer to form the output end of the current ratio standard.

[0012] According to a preferred embodiment of the third aspect of the present application, when the electromagnetic current transformer is configured as a main current transformer and an auxiliary current transformer connected in series on the primary side, connecting the ratio difference compensation module and the angle difference compensation module to the current transformer includes: connecting the terminals on the input side of the ratio difference compensation module and the terminals on the input side of the angle difference compensation module in series and then connecting them in parallel between the terminals on the secondary side of the auxiliary current transformer, connecting the two terminals on the output side of the ratio difference compensation module and the two terminals on the output side of the angle difference compensation module in parallel between the terminals on the secondary side of the main current transformer to form the output end of the current ratio standard, and the terminals on the primary sides of the main current transformer and the auxiliary current transformer that are not connected in series form the input end of the current ratio standard.

[0013] According to a preferred embodiment of the third aspect of the present application, the accuracy of the high-accuracy current ratio standard achieved by this method reaches level 0.02 or higher.

[0014] According to the preferred embodiments of the aforementioned various aspects of the present application, the first precision adjustable resistor and the second precision adjustable resistor are both multi-turn adjustable resistors, and the maximum resistance values ​​of the first precision adjustable resistor and the second precision adjustable resistor are both configured to be at least 10,000 times the impedance of the rated secondary load of the main current transformer.

[0015] According to a preferred embodiment of the aforementioned various aspects of the present application, the rated secondary load of the main current transformer is a resistive load.

[0016] According to the preferred embodiments of the aforementioned various aspects of the present application, the accuracy of the main current transformer reaches at least level 0.1.

[0017] According to the preferred embodiments of the aforementioned various aspects of the present application, the current transformer used by the compensation current transformer of the ratio difference compensation module is a current transformer with an accuracy of level 1 or higher.

[0018] The high-accuracy current ratio standard and implementation method provided by the present application have the following advantages: (1) A high-accuracy current ratio standard can be conveniently implemented using an electromagnetic current transformer of conventional accuracy; (2) When the error of the current ratio standard exceeds the rated limit range, the ratio difference and angle difference of the current ratio standard can be adjusted respectively through continuously adjustable error compensation, so that the current ratio standard can conveniently achieve high accuracy; (3) The ratio difference compensation module of the current ratio standard can compensate for the ratio difference current component that is in phase with the secondary current vector, and the angle difference compensation module of the current ratio standard can compensate for the angle difference current component that is orthogonal to the secondary current vector. The angle difference compensation has higher accuracy and better high-frequency response performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] One or more embodiments of the present application are exemplarily described by corresponding drawings, which do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings represent similar elements, and unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0020] Figure 1 The working principle diagram of the current transformer is shown.

[0021] Figure 2 A circuit schematic diagram of a current ratio standard according to a first embodiment of the present application is shown.

[0022] Figure 3 A circuit schematic diagram of a current ratio standard according to a second embodiment of the present application is shown.

[0023] Figure 4 A circuit schematic diagram of a current ratio standard according to a third embodiment of the present application is shown.

[0024] Figure 5 A circuit schematic diagram showing a current ratio standard according to a first embodiment of the present application connected with an AC current source and a secondary load for error compensation.

[0025] Figure 6 A flow chart showing a method for implementing a current ratio standard according to an embodiment of the present application is shown.

[0026] Figure 7 FIG. 4 shows an error compensation vector diagram of a current ratio standard according to an embodiment of the present application.

[0027] Reference numerals

[0028] 1-electromagnetic current transformer, 2-current ratio standard, 10-secondary load of current transformer, 3-ratio compensation module, 30-compensation current transformer, 32-first standard resistor, 34-first precision adjustable resistor, 4-angle difference compensation module, 40-hollow mutual inductance coil, 42-second standard resistor, 44-second precision adjustable resistor, CT1-main current transformer, CT2-auxiliary current transformer, P1, P2-primary terminals of main current transformer, S1, S2-secondary terminals of main current transformer, X P1 , X P2 - Input terminal of the ratio difference compensation module, X S1 , X S2 - Output terminal of the ratio difference compensation module, Y P1 , Y P2 - Input terminal of the angular difference compensation module, Y S1 , Y S2 - output terminal of the angle difference compensation module, A, B- input terminal of the current ratio standard, a, b- output terminal of the current ratio standard, I1- input current of the current ratio standard, I X -Ratio difference compensation current, I Y - Angle difference compensation current, I 20 - Secondary current of the main current transformer, I 21 - The current of the secondary current of the main current transformer after the ratio difference compensation, I 22 - The current of the secondary current of the main current transformer after ratio difference compensation and angle difference compensation, I 30 - The current flowing through the input side of the ratio difference compensation module, I 40 - Current flowing through the input side of the angular error compensation module, U 40 -The induced voltage generated on the secondary side of the hollow mutual inductance coil, R1-the resistance value of the first standard resistor, R2-the resistance value of the second standard resistor, R X -The resistance of the first precision adjustable resistor, R Y -The resistance of the second precision adjustable resistor, R b -Impedance value of the secondary load, AC - alternating current source. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0030] It should be noted that, if there is no conflict, the various features in the embodiments of the present application can be combined with each other, all within the scope of protection of the present application. In addition, although the functional modules are divided in the schematic diagram and the logical order is shown in the flow chart, in some cases, the steps shown or described can be performed in a different order from the module division in the schematic diagram or the order in the flow chart.

[0031] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used in this specification includes any and all combinations of one or more of the related listed items.

[0032] The following will be combined with the drawings of the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application, so as to make the purpose and advantages of the present application clearer. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments.

[0033] Figure 1 The working principle diagram of the electromagnetic current transformer 1 is shown. When the alternating current source AC is connected between the primary terminals P1 and P2 of the electromagnetic current transformer 1, the primary current output by the alternating current source AC flows through the primary winding of the electromagnetic current transformer 1. According to the principle of electromagnetic induction, an electromotive force will be induced in the secondary winding of the electromagnetic current transformer 1. When the secondary terminals S1 and S2 are connected to the secondary load 10, a secondary current flowing through the secondary load 10 will be generated.

[0034] Figure 2 The circuit schematic diagram of the current ratio standard 2 according to the first embodiment of the present application is shown. The current ratio standard 2 includes a single electromagnetic current transformer 1 (also called a main current transformer CT1) with an accuracy of at least level 1, a ratio difference compensation module 3 and an angle difference compensation module 4 connected to the electromagnetic current transformer 1. Preferably, the accuracy of the electromagnetic current transformer 1 is at least level 0.1.

[0035] Further references Figure 2 The output terminals a and b of the current ratio standard 2 are formed by the secondary terminals S1 and S2 of the main current transformer CT1. The ratio difference compensation module 3 of the current ratio standard 2 is connected by the compensation current transformer 30, the first standard resistor 32 and the first precision adjustable resistor 34 to form a four-terminal network. Specifically, the input terminal X P1 , X P2The first standard resistor 32 is connected in parallel between the secondary terminals of the compensating current transformer 30, and the first precision adjustable resistor 34 is connected in series with the first standard resistor 32, and the unconnected ends of the two form the output terminal Y of the ratio difference compensation module 3. S1 , Y S2 The angle difference compensation module 4 of the current ratio standard 2 is connected by a hollow mutual inductance coil 40, a second standard resistor 42 and a second precision adjustable resistor 44 to form a four-terminal network. Specifically, the input side terminal Y of the angle difference compensation module 4 P1 , Y P2 The two ends of the primary coil of the hollow mutual inductance coil 40 are led out, the second standard resistor 42 and the second precision adjustable resistor 44 are connected in series with the secondary coil of the hollow mutual inductance coil 40, and the unconnected ends of the secondary coil of the hollow mutual inductance coil 40, the second standard resistor 42 or the second precision adjustable resistor 44 form the output side terminal Y of the angle difference compensation module 4. S1 , Y S2 .

[0036] exist Figure 2 In the embodiment shown, the input side terminal X of the ratio difference compensation module 3 P1 , X P2 The terminals P2 on the primary side of the main current transformer CT1 and Y on the input side of the angle difference compensation module 4 are connected to the P1 Connect the other terminal P1 of the primary side of the main current transformer CT1 and the other terminal Y of the input side of the angle difference compensation module 4 P2 The input terminals A and B of the current ratio standard 2 and the output terminal Y of the ratio difference compensation module 3 are formed. S1 , Y S2 And the output terminal Y of the angular difference compensation module 4 P1 , Y P2 They are connected in parallel between the terminals S1 and S2 on the secondary side of the main current transformer CT1 to form the output terminals a and b of the current ratio standard 2.

[0037] exist Figure 2In the illustrated embodiment, the current transformation ratio of the compensating current transformer 30 of the ratio difference compensation module 3, the resistance value of the first standard resistor 32, and the resistance value and adjustment range of the first precision adjustable resistor 34 can be configured according to the ratio difference, rated transformation ratio, and rated secondary load of the main current transformer CT1 under rated conditions. The number of turns and coil size of the hollow mutual inductance coil 40 of the angle difference compensation module 4, the resistance value of the second standard resistor 42, and the resistance value and adjustment range of the second precision adjustable resistor 44 can be configured according to the angle difference, rated transformation ratio, rated secondary load of the main current transformer CT1 under rated conditions, and the AC frequency of the rated conditions. The ratio difference compensation module 3 is configured to compensate for the predetermined ratio difference compensation amount of the main current transformer CT1 by adjusting the resistance value of the first precision adjustable resistor 34 to compensate for the ratio difference of the main current transformer CT1, so that the ratio difference of the current ratio standard 2 is within the ratio difference limit range required by high accuracy; the angle difference compensation module 4 is configured to compensate for the predetermined angle difference compensation amount of the main current transformer CT1 by adjusting the resistance value of the second precision adjustable resistor 44 to compensate for the angle difference of the main current transformer CT1, so that the angle difference of the current ratio standard 2 is within the angle difference limit range required by high accuracy.

[0038] Figure 3 The circuit schematic diagram of the current ratio standard 2 according to the second embodiment of the present application is shown. The current ratio standard 2 includes two electromagnetic current transformers 1 ( Figure 3 , respectively indicated as main current transformer CT1 and auxiliary current transformer CT2), and ratio difference compensation module 3 and angle difference compensation module 4 connected to main current transformer CT1 and auxiliary current transformer CT2. Preferably, the accuracy of main current transformer CT1 and auxiliary current transformer CT2 reaches at least level 0.1.

[0039] Further references Figure 3 The output terminals a and b of the current ratio standard 2 are formed by the secondary terminals S1 and S2 of the main current transformer CT1. The four-terminal network structure of the ratio difference compensation module 3 and the angle difference compensation module 4 is similar to that described in the first embodiment described above, and will not be repeated here. Figure 3 In the embodiment shown, the input side terminal X of the ratio difference compensation module 3 P1 , X P2 The input terminal of the angle difference compensation module 4 is connected in series and then connected between the terminals of the secondary side of the auxiliary current transformer CT2. The output terminal Y S1 , Y S2 And the output terminal Y of the angular difference compensation module 4 P1 , Y P2They are connected in parallel between the terminals S1 and S2 on the secondary side of the main current transformer CT1 to form the output terminals a and b of the current ratio standard 2. The terminals on the primary side of the main current transformer CT1 and the auxiliary current transformer CT2 that are not connected in series form the input terminals A and B of the current ratio standard 2.

[0040] exist Figure 3 In the illustrated embodiment, the current transformation ratio of the compensating current transformer 30 of the ratio difference compensation module 3, the resistance value of the first standard resistor 32, and the resistance value and adjustment range of the first precision adjustable resistor 34 can be configured according to the ratio difference, rated transformation ratio, rated secondary load of the main current transformer CT1 under rated working conditions, and the current transformation ratio of the auxiliary current transformer CT2. The number of turns and coil size of the hollow mutual inductance coil 40 of the angle difference compensation module 4, the resistance value of the second standard resistor 42, and the resistance value and adjustment range of the second precision adjustable resistor 44 can be configured according to the angle difference, rated transformation ratio, rated secondary load, AC frequency of the rated working conditions, and the current transformation ratio of the auxiliary current transformer CT2 under rated working conditions. The ratio difference compensation module 3 is configured to compensate for the predetermined ratio difference compensation amount of the main current transformer CT1 by adjusting the resistance value of the first precision adjustable resistor 34 to compensate for the ratio difference of the main current transformer CT1, so that the ratio difference of the current ratio standard 2 is within the ratio difference limit range required by high accuracy; the angle difference compensation module 4 is configured to compensate for the predetermined angle difference compensation amount of the main current transformer CT1 by adjusting the resistance value of the second precision adjustable resistor 44 to compensate for the angle difference of the main current transformer CT1, so that the angle difference of the current ratio standard 2 is within the angle difference limit range required by high accuracy.

[0041] Figure 4 The circuit schematic diagram of the current ratio standard 2 according to the third embodiment of the present application is shown. The current ratio standard 2 includes a single electromagnetic current transformer 1 with an accuracy of at least level 1, a ratio difference compensation module 3 and an angle difference compensation module 4 connected to the electromagnetic current transformer 1. Figure 4 The four-terminal network structure of the ratio difference compensation module 3 and the angle difference compensation module 4 in the embodiment shown is also similar to that in the first embodiment described above, so it will not be repeated. Figure 4 The input terminal X of the ratio difference compensation module 3 in the embodiment shown is P1 , X P2 The input terminals of the angle difference compensation module 4 are connected in series and then connected between the terminals of the secondary side of the electromagnetic current transformer 1, while the input terminals A, B and output terminals a, b of the current ratio standard 2 are formed by the primary terminals P1, P2 and the secondary terminals S1, S2 of the electromagnetic current transformer 1. Figure 4In the embodiment shown, since the equivalent resistance formed by the connection between the ratio difference compensation module 3 and the angle difference compensation module 4 is in parallel with the secondary load of the electromagnetic current transformer 1, the influence of its impedance on the shunting of the secondary current of the electromagnetic current transformer 1 cannot be ignored. Therefore, this embodiment is only applicable to the case where the electromagnetic current transformer 1 is loaded with a fixed secondary load.

[0042] In practice, the ratio difference and angle difference of the electromagnetic current transformer 1 and the current ratio standard 2 can be obtained by the measurement method recorded in the existing JJG 313-1010 regulations, thereby obtaining the corresponding ratio difference compensation amount and angle difference compensation amount. As an alternative, the ratio difference compensation amount and angle difference compensation amount can also be obtained by other measurement methods known to those skilled in the art.

[0043] The present application is based on the principle of item-by-item approximation, and adopts the ratio difference compensation module 3 and the angle difference compensation module 4 to realize item-by-item approximation compensation for the ratio difference compensation amount and the angle difference compensation amount of the main current transformer CT1. The significant advantage is that even if the current ratio standard 2 has an error offset due to a change in circuit element performance or an environmental change, the ratio difference compensation module 3 and the angle difference compensation module 4 can realize convenient compensation for the offset ratio difference and the angle difference, respectively, and the compensation process of the ratio difference and the angle difference is continuous, linear and controllable, thereby ensuring that the current ratio standard 2 is maintained at a high accuracy after error compensation.

[0044] refer to Figure 5 , shows a circuit schematic diagram of the current ratio standard 2 connected with the AC current source AC and the secondary load 10 for error compensation according to the first embodiment of the present application. In particular, the AC current source AC can output an AC current signal whose effective value is the rated primary current of the main current transformer CT1 and the current of each corresponding rated measurement point. Specifically, Figure 5In the embodiment shown, the main function of the compensation current transformer 30 of the ratio difference compensation module 3 is to obtain the current component in phase with the secondary current vector of the main current transformer CT1, so as to realize the ratio difference component in phase compensation of the secondary current of the main current transformer CT1; the main function of the hollow mutual inductance coil 40 of the angle difference compensation module 4 is to obtain the current component orthogonal to the phase of the secondary current vector, so as to realize the angle difference component orthogonal to the secondary current compensation of the main current transformer CT1. The basic principle of obtaining orthogonal current components in this application is based on Ampere's law and the law of electromagnetic induction. In particular, after the alternating current flows through the primary coil of the hollow mutual inductance coil 40, the phase of the induced electromotive force generated by the secondary coil is shifted by 90° compared to the phase of the alternating current. Considering that the secondary current of the main current transformer CT1 is basically in phase with the alternating current flowing through the primary coil of the hollow mutual inductance coil 40, the current flowing through the secondary coil of the hollow mutual inductance coil 40 is extracted through a resistor connected to the hollow mutual inductance coil 40, so that an angle difference compensation current vector that is approximately orthogonal in phase to the secondary current of the main current transformer CT1 can be obtained.

[0045] In particular, Figure 5 The ratio difference compensation module 3 shown in the dotted frame includes: a compensating current transformer 30, a first standard resistor 32 connected in parallel with the secondary side of the compensating current transformer 30, and a first precision adjustable resistor 34 connected to the first standard resistor 32. The parameters of the ratio difference compensation module 3 are configured according to the ratio difference, rated transformation ratio and rated secondary load of the main current transformer CT1 under rated working conditions. If the series branch of the first precision adjustable resistor 34 and the secondary load of the main current transformer CT1 shunts a ratio difference compensation current corresponding to the predetermined ratio difference compensation amount of the main current transformer CT1 from the secondary side of the compensating current transformer 30, the parameter configuration of the ratio difference compensation module 3 needs to satisfy the following formula:

[0046] I 30 / K1*R1 / (R1+R x +R b )= I1 / K0*ΔI f Formula (1),

[0047] Among them, I 30 represents the current flowing through the input side of the ratio difference compensation module 3 (i.e., the primary current value flowing through the compensation current transformer 30), I1 represents the primary current flowing through the main current transformer CT1, and R x represents the resistance value of the first precision adjustable resistor 34, R1 represents the resistance value of the first standard resistor 32, and R b represents the impedance value of the rated secondary load of the main current transformer CT1, K0 represents the rated transformation ratio of the main current transformer CT1, K1 represents the current transformation ratio of the compensating current transformer 30, ΔI fIn this embodiment, the current I flowing through the input side of the ratio difference compensation module 3 is 30 The same as the primary current I1 flowing through the main current transformer CT1, therefore, the following formula can be obtained from formula (1):

[0048] R x =R1*K0 / (K1*ΔI f )-R1-R b Formula (1.1),

[0049] In this way, the ratio difference compensation module 3 can provide the secondary current I 20 Compensation for the ratio difference compensation current I corresponding to the predetermined ratio difference compensation amount of the main current transformer CT1 X .

[0050] Figure 5 The angle difference compensation module 4 shown in another dotted frame includes: a hollow mutual inductance coil 40, a second standard resistor 42 and a second precision adjustable resistor 44 connected in series with the secondary coil of the hollow mutual inductance coil 40. The parameters of the angle difference compensation module 4 are configured according to the angle difference, rated transformation ratio, rated secondary load and AC frequency of the rated working condition of the main current transformer CT1. If the series resistance of the second standard resistor 42, the second precision adjustable resistor 44 and the secondary load of the main current transformer CT1 generates an angle difference compensation current corresponding to the predetermined angle difference compensation amount of the main current transformer CT1, the parameters of the angle difference compensation module 4 need to satisfy the following formula (2):

[0051] R Y =U 40 *K0 / (ΔI δ *I1)-R2-R b Formula (2.1),

[0052] Among them, R Y represents the resistance value of the second precision adjustable resistor 44, K0 represents the rated transformation ratio of the main current transformer CT1, ΔI δ represents the angle difference compensation required by the main current transformer CT1, I1 represents the rated primary current value of the main current transformer CT1, R2 represents the resistance value of the second standard resistor 42, R b Indicates the impedance value of the rated secondary load of the main current transformer CT1, U 40 In this way, the angle difference compensation module 4 can make the secondary current I of the main current transformer CT1 20 Compensate the angle difference compensation current I corresponding to the predetermined angle difference compensation amount of the main current transformer CT1 Y .

[0053] The induced voltage generated by the secondary coil of the hollow mutual inductance coil 40 is equal to the product of the rate of change of the magnetic flux in the circular cross section of the hollow mutual inductance coil 40 and the number of turns of the secondary coil of the hollow mutual inductance coil 40. The magnetic flux in the circular cross section of the hollow mutual inductance coil 40 is equal to the product of the magnetic induction intensity in the hollow mutual inductance coil 40 and the circular cross-sectional area surrounded by the hollow mutual inductance coil 40. It is well known to those skilled in the art that the magnetic induction intensity in the hollow mutual inductance coil 40 is uniformly distributed at the central cross section and can be calculated by a predetermined formula. Therefore, the induced voltage U generated by the secondary coil of the hollow mutual inductance coil 40 is 40 It can be obtained by the following formula:

[0054]

[0055] Among them, U 40 represents the induced voltage value generated on the secondary side of the hollow mutual inductance coil 40, μ0 represents the magnetic permeability of air, π is the circumference, N1 and N2 represent the number of turns of the primary and secondary sides of the hollow mutual inductance coil 40, respectively, L represents the axial length of the primary coil of the hollow mutual inductance coil 40, D represents the diameter of the circular cross section surrounded by the hollow mutual inductance coil 40, f represents the AC frequency of the rated working condition, I1 represents the rated primary current value of the main current transformer CT1 (which is the same as the current I flowing through the primary coil of the hollow mutual inductance coil 40). 40 same).

[0056] In such Figure 3 In the embodiment shown in , the current transformer is configured as a main current transformer CT1 and an auxiliary current transformer CT2 connected in series on the primary side, and the current flowing through the input side of the ratio difference compensation module 3 and the angle difference compensation module 4 is the secondary current of the auxiliary current transformer CT2. At this time, the parameter configuration of the ratio difference compensation module should satisfy the following formula to enable the series branch of the first precision adjustable resistor 34 and the secondary load of the main current transformer CT1 to shunt the ratio difference compensation current corresponding to the predetermined ratio difference compensation amount of the main current transformer CT1 from the secondary side of the compensation current transformer 30:

[0057] R x =R1*K0 / (K1*K2*ΔI f )-R1-R b Formula (1.2),

[0058] Among them, R x represents the resistance value of the first precision adjustable resistor 34, R1 represents the resistance value of the first standard resistor 32, K0 represents the rated transformation ratio of the main current transformer CT1, K1 represents the current transformation ratio of the compensation current transformer 30, K2 represents the current transformation ratio of the auxiliary current transformer CT2, ΔI f Indicates the required differential compensation of the main current transformer CT1, R bIndicates the impedance value of the rated secondary load of the main current transformer CT1.

[0059] The parameter configuration of the angular difference compensation module 4 should still satisfy the formula (2.1) described above. For the difference in formula number, Figure 3 The parameter configuration formula of the angular difference compensation module 4 in the embodiment shown in is numbered as formula (2.2).

[0060] R Y =U 40 *K0 / (ΔI δ *I1)-R2-R b Formula (2.2),

[0061] The induced voltage value generated on the secondary side of the hollow mutual inductance coil 40 is obtained by the following formula:

[0062]

[0063] Among them, U 40 represents the induced voltage value generated on the secondary side of the hollow mutual inductance coil 40, μ0 represents the magnetic permeability of air, π is the pi, N1 and N2 represent the number of coil turns on the primary and secondary sides of the hollow mutual inductance coil 40 respectively, L represents the axial length formed by the densely wound primary coil of the hollow mutual inductance coil 40, D represents the diameter of the circular cross-section surrounded by the hollow mutual inductance coil 40, f represents the AC frequency of the rated operating condition, I1 represents the rated primary current value of the main current transformer CT1, and K2 represents the current transformation ratio of the auxiliary current transformer.

[0064] Continue to refer Figure 5 To explain the principle of error compensation for the main current transformer CT1, after the current ratio standard 2 is connected to the AC current source AC and the secondary load 10, the current of the primary side of the AC current source AC input current ratio standard 2 is marked as I1, and the secondary current of the main current transformer CT1 is marked as I 20 , secondary current I 20 After the ratio difference compensation, it is marked as I 21 , the current after further angle difference compensation is marked as I 22 , I 22 That is, the current flowing through the secondary load 10 between the output terminals a and b of the current ratio standard 2. In other words, I 22 is the secondary current of current ratio standard 2.

[0065] It should be noted that, since the secondary load of the current ratio standard 2 is usually a resistive load with a very small resistance value, in order to avoid the branch formed by the first standard resistor 32 of the ratio difference compensation module 3 and the first precision adjustable resistor 34 in series, and the branch formed by the second standard resistor 42 and the second precision adjustable resistor 44 of the angle difference compensation module 4 in series, relative to the secondary load 10 of the main current transformer CT1, the secondary current I 20 The error caused by shunting is too large, and the total resistance of the first standard resistor 32 and the first precision adjustable resistor 34 and the total resistance of the second standard resistor 42 and the second precision adjustable resistor 44 should be configured to be at least three orders of magnitude greater than the impedance of the rated secondary load of the main current transformer CT1. In view of the fact that the first standard resistor 32 and the second standard resistor 42 are resistors with limited resistance for protection, and the first precision adjustable resistor 34 and the second precision adjustable resistor 44 need to have a certain adjustment range, the maximum resistance of the first precision adjustable resistor 34 and the second precision adjustable resistor 44 should be configured to be at least 10,000 times the impedance of the rated secondary load of the main current transformer. Preferably, the first precision adjustable resistor 34 and the second precision adjustable resistor 44 are both configured as multi-turn adjustable resistors, and the adjustment fineness can reach one ten-thousandth of the maximum resistance.

[0066] The principle of achieving ratio difference compensation and angle difference compensation by the ratio difference compensation module 3 and the angle difference compensation module 4 is based on Ohm's law, that is, the resistance shunt principle. Since the total resistance of the first standard resistor 32 and the first precision adjustable resistor 34 and the total resistance of the second standard resistor 42 and the second precision adjustable resistor 44 are much larger than the rated secondary load impedance of the main current transformer CT1, the secondary current I injected into the main current transformer CT1 by the ratio difference compensation module 3 is 20 The ratio difference compensation current I x The value is roughly I1*R1 / K1(R x +R1+R b ), combined with formula (1.1), the ratio difference compensation current can be obtained:

[0067] I x =ΔI f *I1 / K0 formula (4),

[0068] The current flowing through the second standard resistor 42 (that is, the angle difference compensation current I Y ) is roughly I Y =U 40 / (R Y +R2+R b ), combined with the above formula (2.1) or formula (2.2), the angle difference compensation current can be obtained:

[0069] I Y =ΔI δ*I1 / K0 formula (5),

[0070] It should be noted that the angle difference compensation current I Y And the ratio difference compensation current I x As mentioned above, after the hollow mutual inductance coil 40 of the angle difference compensation module 4 generates a secondary induced voltage through electromagnetic induction, the phase of the current flowing through the second standard resistor 42 is greater than the phase of the current I flowing through the primary side of the hollow mutual inductance coil. 40 The phase of the phase shift is 90°, and the current I flowing through the primary side of the hollow mutual inductance coil is 40 (Right now, Figure 5 The primary current I1 of the main current transformer CT1 and the secondary current I 20 Basically in phase, so the angle difference compensation current I Y Compared with the secondary current I of the main current transformer CT1 20 The phase difference is about 90°. In contrast, the ratio compensation current I x The secondary current I of the main current transformer CT1 20 Basically in phase.

[0071] refer to Figure 6, showing a flow chart of the implementation method of the current ratio standard 2 according to the embodiment of the present application. The method comprises the following steps: S1, obtaining an electromagnetic current transformer with an accuracy of at least level 1 and measuring its ratio difference and angle difference under rated working conditions, wherein the current transformer is configured as a single main current transformer or a main current transformer and an auxiliary current transformer connected in series on the primary side; S2, calculating the ratio difference compensation amount and angle difference compensation amount to be applied to the main current transformer to implement a high-accuracy current ratio standard based on the ratio difference and angle difference of the current transformer; S3, configuring the parameters of the ratio difference compensation module according to the rated transformation ratio, rated secondary load and ratio difference compensation amount of the main current transformer, according to The rated transformation ratio of the main current transformer, the rated secondary load, the AC frequency of the rated working condition and the angle difference compensation amount configure the parameters of the angle difference compensation module, wherein the ratio difference compensation module is connected by the compensation current transformer, the first standard resistor and the first precision adjustable resistor to form a four-terminal network, and the angle difference compensation module is connected by the hollow mutual inductance coil, the second standard resistor and the second precision adjustable resistor to form a four-terminal network. The parameters of the ratio difference compensation module include: the transformation ratio of the compensation current transformer, the resistance value of the first standard resistor, and the resistance value and adjustment range of the first precision adjustable resistor, and the parameters of the angle difference compensation module Including: the number of turns and coil size of the hollow mutual inductance coil, the resistance value of the second standard resistor, and the resistance value and adjustment range of the second precision adjustable resistor; S4, connecting the ratio difference compensation module and the angle difference compensation module to the current transformer to form a current ratio standard; S5, measuring the ratio difference and angle difference of the current ratio standard under rated working conditions, and verifying the level of the ratio difference and angle difference of the current ratio standard; S6, judging whether the ratio difference or angle difference of the current ratio standard exceeds the error limit range required by high accuracy, if not, the verification is qualified and go to step S8, otherwise continue to step S 7; S7, if the ratio error of the current ratio standard exceeds the ratio error limit range required by high accuracy, the ratio error of the current ratio standard is compensated by adjusting the resistance value of the first precision adjustable resistor; if the angular difference of the current ratio standard exceeds the angular difference limit range required by high accuracy, the angular difference of the current ratio standard is compensated by adjusting the resistance value of the second precision adjustable resistor, and then go to step S5; S8, to complete the realization of the high-accuracy current ratio standard, that is, the ratio error and angular difference of the current ratio standard are within the error limit range required by high accuracy after compensation.

[0072] The electromagnetic current transformer 1 is configured as follows Figure 2In the case of a single main current transformer CT1 shown in , the step S4 of the above method of connecting the ratio difference compensation module 3 and the angle difference compensation module 4 to the current transformer includes: connecting the two terminals on the input side of the compensation current transformer 30 to the terminals on the primary side of the main current transformer CT1 and one terminal on the input side of the angle difference compensation module 4, respectively, so that the other terminal on the primary side of the main current transformer CT1 and the other terminal on the input side of the angle difference compensation module 4 form the input end of the current ratio standard 2, and the two terminals on the output side of the ratio difference compensation module 3 and the two terminals on the output side of the angle difference compensation module 4 are connected in parallel between the terminals on the secondary side of the main current transformer CT1 to form the output end of the current ratio standard 2. The parameter configuration of the ratio difference compensation module 3 and the angle difference compensation module 4 is obtained according to the formulas 1.1, 2.1, and 3.1 described above.

[0073] The electromagnetic current transformer 1 is configured as follows Figure 3 In the case of the main current transformer CT1 and the auxiliary current transformer CT2 connected in series on the primary side as shown in , the step S4 of the above method connects the ratio difference compensation module 3 and the angle difference compensation module 4 to the current transformer, including: connecting the terminals on the input side of the ratio difference compensation module 3 and the terminals on the input side of the angle difference compensation module 4 in series and then connecting them between the terminals on the secondary side of the auxiliary current transformer CT2, connecting the two terminals on the output side of the ratio difference compensation module 3 and the two terminals on the output side of the angle difference compensation module 4 in parallel between the terminals on the secondary side of the main current transformer to form the output end of the current ratio standard, and the terminals on the primary side of the main current transformer CT1 and the auxiliary current transformer CT2 that are not connected in series form the input end of the current ratio standard. The parameter configuration of the ratio difference compensation module 3 and the angle difference compensation module 4 is obtained according to the formulas 1.2, 2.2, and 3.2 described above.

[0074] In practice, the terminals on the output side of the ratio difference compensation module 3 and the terminals on the secondary side of the main current transformer CT1 can be configured to be connected in pairs of opposite ends or in pairs of the same end according to the positive or negative of the ratio difference of the main current transformer CT1. Similarly, the terminals on the output side of the angle difference compensation module 4 and the terminals on the secondary side of the main current transformer CT1 can be configured to be connected in pairs of opposite ends or in pairs of the same end according to the positive or negative of the angle difference of the main current transformer CT1.

[0075] It can be understood that the significant advantage of the ratio difference compensation module 3 configured according to the present application is that when the ratio difference of the current ratio standard 2 exceeds the limit and needs to be compensated, the resistance value R of the first precision adjustable resistor 34 can be continuously adjusted. x Similarly, the significant advantage of the angle difference compensation module 4 is that when the angle difference of the current ratio standard 2 exceeds the limit and needs to be compensated, the resistance value R of the second precision adjustable resistor 44 can be continuously adjusted. YAccurate compensation of angular difference is achieved. The compensation process of ratio difference and angular difference is continuous, linear and controllable.

[0076] Figure 7 A vector diagram showing error compensation of the current ratio standard 2 according to an embodiment of the present application is shown. Figure 5 and Figure 7 , assuming that I1 is the input current of current ratio standard 2, I 20 is the secondary current of the main current transformer CT1 in the current ratio standard 2. The error compensation process of the current ratio standard 2 is as follows: first, the secondary current I of the main current transformer CT1 is compensated by the ratio difference compensation module 3. 20 Compensate the current I x The vector compensation of the main current transformer CT1 is 20 The current vector changes after the ratio difference compensation to I 21 Then the current I after the main current transformer CT1 is compensated by the angle difference compensation module 4 21 Further angular difference compensation current I Y The vector compensation of the main current transformer CT1 is finally realized by ΔI=I x +j*I Y Error compensation, where j is an imaginary unit, the secondary current I of the main current transformer CT1 20 After the vector current ΔI is compensated, it changes to I 22 , that is, the output current of the current ratio standard 2. Figure 7 In the ratio compensation current I x The angle difference compensation current I Y The vectors of are roughly orthogonal, and their vector sum is the vector current ΔI to be compensated, where α is the vector current ΔI to be compensated relative to the secondary current vector I 20 , θ is the final angle compensation.

[0077] For the current ratio standard 2 formed by adding the ratio difference compensation module 3 and the angle difference compensation module 4 to the main current transformer CT1, in some cases, the output current I after the ratio difference compensation and the angle difference compensation are performed on the secondary current of the main current transformer CT1 is 22The ratio difference or angle difference between the input current I1 of the current ratio standard 2 may still not meet the ratio difference and angle difference required by the high-accuracy current ratio standard 2. In this case, it is only necessary to measure the ratio difference and angle difference of the current ratio standard 2 under the rated working condition and calculate the predetermined ratio difference compensation amount or predetermined angle difference compensation amount to be applied to it to realize the high-accuracy current ratio standard. The ratio difference compensation module 3 can still compensate the ratio difference between the output current and the input current of the current ratio standard 2 by the predetermined ratio difference compensation amount, and the angle difference compensation module 4 can compensate the angle difference between the output current and the input current of the current ratio standard 2 by the predetermined angle difference compensation amount.

[0078] Specifically, if the ratio error of the current ratio standard 2 exceeds the ratio error limit range required for high accuracy, the ratio error of the current ratio standard 2 can be compensated by adjusting the resistance value of the first precision adjustable resistor 34 until the ratio error measured by the current ratio standard 2 under rated conditions is within the ratio error limit range required for high accuracy; similarly, if the angular difference of the current ratio standard 2 exceeds the angular difference limit range required for high accuracy, the angular difference of the current ratio standard 2 can be compensated by adjusting the resistance value of the second precision adjustable resistor 44 until the angular difference measured by the current ratio standard 2 under rated conditions is within the angular difference limit range required for high accuracy. In this way, it can be ensured that the current ratio standard 2 maintains high accuracy after error compensation. The vector diagram of the error compensation of the current ratio standard 2 is similar to the above reference diagram. Figure 7 The description is similar to that of FIG. 1 , and only the vectors in the figure need to be replaced with the corresponding vectors of the current ratio standard 2. For example, I 20 ,I x ,I Y The secondary current vector, ratio difference compensation current and angle difference compensation current of the current proportion standard device 2 are replaced respectively. The compensation principle is the same as described above and will not be repeated here.

[0079] The significant advantages of the present application include: (1) using an ordinary main current transformer with an accuracy of at least level 1 to conveniently realize a current ratio standard with an accuracy of not less than level 0.02; (2) when the error of the current ratio standard exceeds the rated limit range, the ratio difference and the angle difference of the current ratio standard can be adjusted respectively through continuously adjustable error compensation, so that the current ratio standard can achieve high accuracy, and the compensation process of the ratio difference and the angle difference is continuous, linear and controllable, thereby ensuring that the error of the current ratio standard is within the error limit required for high accuracy; (3) The angle difference compensation module of the current ratio standard uses a hollow mutual inductance coil to obtain the angle difference current component orthogonal to the secondary current vector. The angle difference compensation has higher accuracy and better high-frequency response performance, and can be applied to the wide-band error compensation of the current ratio standard.

[0080] The various technical features of the above embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the various 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.

[0081] It should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; under the idea of ​​the present application, the technical features in the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other changes in different aspects of the present application as described above, which are not provided in detail for the sake of simplicity; although the present application is described in detail with reference to the above embodiments, ordinary technicians in this field should understand that: it is still possible to modify the technical solutions recorded in the above embodiments, or to replace some of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application. For ordinary technicians in this field, without departing from the concept of the present application, several modifications and improvements can be made, which all belong to the protection scope of the present application.

Claims

1. A high-accuracy current ratio standard, characterized in that: The current ratio standard includes a main current transformer with an accuracy of at least level 1, a ratio difference compensation module and an angle difference compensation module connected to the main current transformer, wherein the ratio difference compensation module is formed by connecting a compensation current transformer, a first standard resistor and a first precision adjustable resistor to form a four-terminal network, and the angle difference compensation module is formed by connecting a hollow mutual inductance coil, a second standard resistor and a second precision adjustable resistor to form a four-terminal network, two terminals on the input side of the ratio difference compensation module are respectively connected to the terminals on the primary side of the main current transformer and one terminal on the input side of the angle difference compensation module, another terminal on the primary side of the main current transformer and another terminal on the input side of the angle difference compensation module form the input end of the current ratio standard, two terminals on the output side of the ratio difference compensation module and two terminals on the output side of the angle difference compensation module are connected in parallel between the terminals on the secondary side of the main current transformer to form the output end of the current ratio standard, Among them, the ratio difference compensation module is configured to compensate for the predetermined ratio difference compensation amount based on the predetermined ratio difference compensation amount by adjusting the ratio difference of the first precision adjustable resistor to the current ratio standard, so that the ratio difference of the current ratio standard is within the ratio difference limit range required by high accuracy; the angle difference compensation module is configured to compensate for the predetermined angle difference compensation amount based on the predetermined angle difference compensation amount by adjusting the second precision adjustable resistor to the angle difference of the current ratio standard, so that the angle difference of the current ratio standard is within the angle difference limit range required by high accuracy.

2. The high-accuracy current ratio standard according to claim 1, characterized in that: The transformation ratio of the compensating current transformer of the ratio difference compensation module, the resistance value of the first standard resistor, and the resistance value and adjustment range of the first precision adjustable resistor are configured according to the ratio difference, rated transformation ratio and rated secondary load of the main current transformer under rated operating conditions. The number of turns and coil size of the hollow mutual inductance coil of the angle difference compensation module, the resistance value of the second standard resistor, and the resistance value and adjustment range of the second precision adjustable resistor are configured according to the angle difference, rated transformation ratio, rated secondary load of the main current transformer under rated operating conditions and the AC frequency of the rated operating conditions.

3. The high-accuracy current ratio standard according to claim 1, characterized in that: The first precision adjustable resistor and the second precision adjustable resistor are both multi-turn adjustable resistors, and the maximum resistance of the first precision adjustable resistor and the second precision adjustable resistor are both configured to be at least 10,000 times the impedance of the rated secondary load of the main current transformer.

4. A high-accuracy current ratio standard, characterized in that: The current ratio standard includes a main current transformer and an auxiliary current transformer with an accuracy of at least level 1 and connected in series on the primary side, and a ratio difference compensation module and an angle difference compensation module connected to the main current transformer and the auxiliary current transformer, wherein the ratio difference compensation module is formed by connecting a compensation current transformer, a first standard resistor and a first precision adjustable resistor to form a four-terminal network, and the angle difference compensation module is formed by connecting a hollow mutual inductance coil, a second standard resistor and a second precision adjustable resistor to form a four-terminal network, the terminals on the primary side of the main current transformer and the auxiliary current transformer that are not connected in series form the input end of the current ratio standard, the terminals on the input side of the ratio difference compensation module and the terminals on the input side of the angle difference compensation module are connected in series and then connected in parallel between the terminals on the secondary side of the auxiliary current transformer, the two terminals on the output side of the ratio difference compensation module and the two terminals on the output side of the angle difference compensation module are both connected in parallel between the terminals on the secondary side of the main current transformer to form the output end of the current ratio standard, Among them, the ratio difference compensation module is configured to compensate for the predetermined ratio difference compensation amount based on the predetermined ratio difference compensation amount by adjusting the ratio difference of the first precision adjustable resistor to the current ratio standard, so that the ratio difference of the current ratio standard is within the ratio difference limit range required by high accuracy; the angle difference compensation module is configured to compensate for the predetermined angle difference compensation amount based on the predetermined angle difference compensation amount by adjusting the second precision adjustable resistor to the angle difference of the current ratio standard, so that the angle difference of the current ratio standard is within the angle difference limit range required by high accuracy.

5. The high-accuracy current ratio standard according to claim 4, characterized in that: The transformation ratio of the compensating current transformer of the ratio difference compensation module, the resistance value of the first standard resistor, and the resistance value and adjustment range of the first precision adjustable resistor are configured according to the ratio difference, rated transformation ratio, rated secondary load of the main current transformer under rated operating conditions and the current transformation ratio of the auxiliary current transformer. The number of turns and coil size of the hollow mutual inductance coil of the angle difference compensation module, the resistance value of the second standard resistor, and the resistance value and adjustment range of the second precision adjustable resistor are configured according to the angle difference, rated transformation ratio, rated secondary load of the main current transformer under rated operating conditions, the AC frequency of the rated operating conditions and the current transformation ratio of the auxiliary current transformer.

6. The high-accuracy current ratio standard according to claim 4, characterized in that: The first precision adjustable resistor and the second precision adjustable resistor are both multi-turn adjustable resistors, and the maximum resistance of the first precision adjustable resistor and the second precision adjustable resistor are both configured to be at least 10,000 times the impedance of the rated secondary load of the main current transformer.

7. A method for realizing a high-accuracy current ratio standard, characterized in that: The method comprises the following steps: S1, obtain an electromagnetic current transformer with an accuracy of at least Class 1 and measure its ratio error and angle error under rated conditions, Wherein, the electromagnetic current transformer is configured as a single main current transformer or a main current transformer and a secondary current transformer connected in series on the primary side; S2, calculating the ratio difference compensation amount and the angle difference compensation amount that the high-accuracy current ratio standard needs to apply to the main current transformer based on the ratio difference and the angle difference of the current transformer; S3, configuring parameters of the ratio difference compensation module according to the rated transformation ratio of the main current transformer, the rated secondary load and the ratio difference compensation amount, and configuring parameters of the angle difference compensation module according to the rated transformation ratio of the main current transformer, the rated secondary load, the AC frequency of the rated working condition and the angle difference compensation amount, The ratio difference compensation module is formed by connecting a compensating current transformer, a first standard resistor and a first precision adjustable resistor to form a four-terminal network, and the angle difference compensation module is formed by connecting a hollow mutual inductance coil, a second standard resistor and a second precision adjustable resistor to form a four-terminal network. The parameters of the ratio difference compensation module include: the transformation ratio of the compensating current transformer, the resistance value of the first standard resistor, and the resistance value and adjustment range of the first precision adjustable resistor. The parameters of the angle difference compensation module include: the number of turns and coil size of the hollow mutual inductance coil, the resistance value of the second standard resistor, and the resistance value and adjustment range of the second precision adjustable resistor. S4, connecting the ratio difference compensation module and the angle difference compensation module to the current transformer to form the current ratio standard; S5, measuring the ratio difference and the angular difference of the current ratio standard under rated working conditions, and verifying the levels of the ratio difference and the angular difference of the current ratio standard; S6, judging whether the ratio error or angle error of the current ratio standard exceeds the error limit range required by high accuracy, if not, the verification is qualified and the process goes to step S8, otherwise, the process continues to step S7; S7, if the ratio difference of the current ratio standard exceeds the ratio difference limit range required by high accuracy, the ratio difference of the current ratio standard is compensated by adjusting the resistance value of the first precision adjustable resistor; if the angular difference of the current ratio standard exceeds the angular difference limit range required by high accuracy, the angular difference of the current ratio standard is compensated by adjusting the resistance value of the second precision adjustable resistor, and then go to step S5; S8, completing the realization of the high-accuracy current ratio standard.

8. The method according to claim 7, characterized in that In the case where the electromagnetic current transformer is configured as a single main current transformer, connecting the ratio difference compensation module and the angle difference compensation module to the current transformer includes: connecting two terminals on the input side of the compensating current transformer to the terminals on the primary side of the main current transformer and one terminal on the input side of the angle difference compensation module, respectively, so that the other terminal on the primary side of the main current transformer and the other terminal on the input side of the angle difference compensation module form the input end of the current ratio standard, and connecting two terminals on the output side of the ratio difference compensation module and two terminals on the output side of the angle difference compensation module in parallel between the terminals on the secondary side of the main current transformer to form the output end of the current ratio standard, whereby the parameter configuration of the ratio difference compensation module satisfies the following formula: R x =R1*K0 / (K1*ΔI f )-R1-R b Formula (1.1), Among them, R x represents the resistance value of the first precision adjustable resistor, R1 represents the resistance value of the first standard resistor, K0 represents the rated transformation ratio of the main current transformer, K1 represents the current transformation ratio of the compensation current transformer, ΔI f represents the ratio difference compensation amount, R b Indicates the impedance value of the rated secondary load of the main current transformer; The parameter configuration of the angular difference compensation module satisfies the following formula: R Y =U 40 *K0 / (ΔI δ *I1)-R2-R b Formula (2.1), Among them, R Y represents the resistance value of the second precision adjustable resistor, K0 represents the rated transformation ratio of the main current transformer, ΔI δ represents the angle difference compensation amount, I1 represents the rated primary current value of the main current transformer, R2 represents the resistance value of the second standard resistor, R b Indicates the impedance value of the rated secondary load of the main current transformer, U 40 Indicates the induced voltage value generated on the secondary side of the hollow mutual inductance coil; The induced voltage on the secondary side of the hollow mutual inductance coil is obtained by the following formula: Among them, U 40 represents the induced voltage value generated on the secondary side of the hollow mutual inductance coil, μ0 represents the magnetic permeability of air, π is the pi, N1 and N2 represent the number of coil turns on the primary and secondary sides of the hollow mutual inductance coil respectively, L represents the axial length formed by the densely wound primary coil of the hollow mutual inductance coil, D represents the diameter of the circular cross-section surrounded by the hollow mutual inductance coil, f represents the AC frequency of the rated operating condition, and I1 represents the rated primary current value of the main current transformer.

9. The method according to claim 7, characterized in that: In the case where the electromagnetic current transformer is configured as a main current transformer and an auxiliary current transformer connected in series on the primary side, connecting the ratio difference compensation module and the angle difference compensation module to the current transformer includes: connecting the terminal on the input side of the ratio difference compensation module and the terminal on the input side of the angle difference compensation module in series and then connecting them in parallel between the terminals on the secondary side of the auxiliary current transformer, connecting the two terminals on the output side of the ratio difference compensation module and the two terminals on the output side of the angle difference compensation module in parallel between the terminals on the secondary side of the main current transformer to form the output end of the current ratio standard, and the terminals on the primary sides of the main current transformer and the auxiliary current transformer that are not connected in series form the input end of the current ratio standard, thereby, the parameter configuration of the ratio difference compensation module satisfies the following formula: R x =R1*K0 / (K1*K2*ΔI f )-R1-R b Formula (1.2), Among them, R x represents the resistance value of the first precision adjustable resistor, R1 represents the resistance value of the first standard resistor, K0 represents the rated transformation ratio of the main current transformer, K1 represents the current transformation ratio of the compensating current transformer, K2 represents the current transformation ratio of the auxiliary current transformer, ΔI f represents the ratio difference compensation amount, R b Indicates the impedance value of the rated secondary load of the main current transformer; The parameter configuration of the angular difference compensation module satisfies the following formula: R Y =U 40 *K0 / (ΔI δ *I1)-R2-R b Formula (2.2), Among them, R Y represents the resistance value of the second precision adjustable resistor, K0 represents the rated transformation ratio of the main current transformer, ΔI δ represents the angle difference compensation amount, I1 represents the rated primary current value of the main current transformer, R2 represents the resistance value of the second standard resistor, R b Indicates the impedance value of the rated secondary load of the main current transformer, U 40 Indicates the induced voltage value generated on the secondary side of the hollow mutual inductance coil; The induced voltage generated on the secondary side of the hollow mutual inductance coil is obtained by the following formula: Among them, U 40 represents the induced voltage value generated on the secondary side of the hollow mutual inductance coil, μ0 represents the magnetic permeability of air, π is the pi, N1 and N2 represent the number of coil turns on the primary and secondary sides of the hollow mutual inductance coil respectively, L represents the axial length formed by the densely wound primary coil of the hollow mutual inductance coil, D represents the diameter of the circular cross-section surrounded by the hollow mutual inductance coil, f represents the AC frequency of the rated operating condition, I1 represents the rated primary current value of the main current transformer, and K2 represents the current transformation ratio of the auxiliary current transformer.

10. The method according to any one of claims 7 to 9, characterized in that The first precision adjustable resistor and the second precision adjustable resistor are both multi-turn adjustable resistors, and the maximum resistance of the first precision adjustable resistor and the second precision adjustable resistor are both configured to be at least 10,000 times the impedance of the rated secondary load of the main current transformer.

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