Circuit, method and use for detecting influence of leakage current on current transformer

Abstract

To solve the technical problem in the prior art that the influence of leakage current on the error of current transformers cannot be detected, an embodiment of the present invention provides a circuit, a method and a use for detecting the influence of leakage current on current transformers. The circuit includes: an optical fiber current transformer, which is used to be connected in series with the high-voltage current transformer to be measured. The method includes: connecting the optical fiber current transformer in series with the high-voltage current transformer to be measured to obtain a circuit; applying a voltage that will not generate leakage current to the circuit and measuring the current values flowing through the high-voltage current transformer and the optical fiber current transformer; applying a voltage that will generate leakage current to the circuit and measuring the current values flowing through the high-voltage current transformer and the optical fiber current transformer. The use of the optical fiber current transformer for detecting the influence of leakage current on the error of current transformers. Through the series connection of the optical fiber current transformer and the high-voltage current transformer to be measured, the embodiment of the present invention realizes the detection of the influence of leakage current on the error of the high-voltage current transformer.

Description

Technical Field

[0001] The present invention relates to a circuit, a method and a use for detecting the influence of leakage current on a current transformer. Background Art

[0002] With the economic development and urbanization construction, a large number of residential communities, commercial buildings, etc. are emerging continuously. When there are only a small number of users in the community or building, or at night during rest or holidays, the actual load current may be lower than 1% of the rated current. On the other hand, with the emergence of new equipment such as high-speed railways, power electronic devices, and overload transformers, when these devices are operating, the current transformer may often operate at a situation higher than 120% In (In is the rated current). Therefore, wide-frequency and wide-range current transformers with a wider current range are gradually being applied, and the range of such wide-frequency and wide-range current transformers is usually 0.1% - 200%.

[0003] Since wide-frequency and wide-range current transformers usually adopt the electromagnetic induction principle, for wide-frequency and wide-range current transformers operating at high voltages such as 10 kV, they are actually operating at a high voltage state. At this time, a leakage current will be generated between the primary and secondary windings, and this leakage current will affect the error characteristics of the wide-frequency and wide-range current transformer. Summary of the Invention

[0004] The inventor has found that the influence of leakage current under small loads such as 0.1% In has to be considered, otherwise it will affect the judgment of its qualification. There is currently no good method for detecting the influence of leakage current on the error of the current transformer.

[0005] To solve the technical problem in the prior art that it is impossible to detect whether the leakage current has an impact on the error of the current transformer, the embodiments of the present invention provide a circuit, a method and a use for detecting the influence of leakage current on a current transformer.

[0006] The embodiments of the present invention are realized through the following technical solutions:

[0007] In a first aspect, the embodiments of the present invention provide a circuit for detecting the influence of leakage current on the error of a current transformer. The circuit includes: an optical fiber current transformer, which is used to be connected in series with the high-voltage current transformer to be measured.

[0008] Further, the circuit includes:

[0009] A line, which is provided with an interface for connecting with the high-voltage current transformer to be measured; and

[0010] An optical fiber current transformer, which is arranged on the line and is used to be connected in series with the high-voltage current transformer to be measured through the interface.

[0011] Further, the high-voltage current transformer is a wide-frequency and wide-range current transformer.

[0012] Further, the power supply of the circuit includes a power supply that does not generate leakage current and a power supply that generates leakage current;

[0013] The power supply that generates leakage current is used to be connected in series with the optical fiber current transformer and the high-voltage current transformer to be measured to obtain the error including leakage current of the high-voltage current transformer;

[0014] The power supply that does not generate leakage current is used to be connected in series with the optical fiber current transformer and the high-voltage current transformer to be measured to obtain the error not including leakage current of the high-voltage current transformer.

[0015] In a second aspect, an embodiment of the present invention provides a method for detecting the influence of leakage current on the error of a current transformer, including:

[0016] Connect the optical fiber current transformer in series with the high-voltage current transformer to be measured to obtain a circuit;

[0017] Apply a voltage that does not generate leakage current to the circuit, and measure the current values flowing through the high-voltage current transformer and the optical fiber current transformer;

[0018] Apply a voltage that generates leakage current to the circuit, and measure the current values flowing through the high-voltage current transformer and the optical fiber current transformer.

[0019] Further, the step of applying a voltage that does not generate leakage current to the circuit and measuring the current values flowing through the high-voltage current transformer and the optical fiber current transformer includes: applying a voltage that does not generate leakage current to the circuit, measuring the current values flowing through the high-voltage current transformer and the optical fiber current transformer, and comparing to obtain the error not including leakage current of the high-voltage current transformer;

[0020] The step of applying a voltage that generates leakage current to the circuit and measuring the current values flowing through the high-voltage current transformer and the optical fiber current transformer includes: applying a voltage that generates leakage current to the circuit, measuring the current values flowing through the high-voltage current transformer and the optical fiber current transformer, and comparing to obtain the error including leakage current of the high-voltage current transformer;

[0021] Compare the error including leakage current with the error not including leakage current to obtain a difference value, and this difference value is the influence amount of the leakage current on the error of the high-voltage current transformer.

[0022] Further, the high-voltage current transformer to be measured is a wide-bandwidth and wide-range current transformer.

[0023] Further, the rated voltage of the wide-bandwidth and wide-range current transformer is above 1 KV.

[0024] In a third aspect, an embodiment of the present invention provides a use of an optical fiber current transformer for detecting the influence of leakage current on the error of a current transformer.

[0025] Compared with the prior art, the embodiment of the present invention has the following advantages and beneficial effects:

[0026] The circuit, method and use for detecting the influence of leakage current on a current transformer in the embodiment of the present invention realize the detection of the influence of leakage current on the error of a high-voltage current transformer by connecting an optical fiber current transformer in series with the high-voltage current transformer to be measured. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the drawings required for the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0028] Figure 1 Schematic diagram of a partial structure of a circuit for detecting the influence of leakage current on a current transformer.

[0029] Figure 2 Schematic diagram of a method flow for detecting the influence of leakage current on the error of a current transformer.

[0030] Marks in the drawings and corresponding component names:

[0031] In the figure, 1 - optical fiber current transformer, 2 - broadband wide-range current transformer. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] To make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the embodiments and the drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0033] In the following description, a large number of specific details are set forth in order to provide a thorough understanding of the present invention. However, it is obvious to those of ordinary skill in the art that the present invention does not have to be implemented with these specific details. In other embodiments, well-known structures, circuits, materials or methods are not specifically described in order to avoid obscuring the present invention.

[0034] Throughout the specification, references to "one embodiment", "an embodiment", "one example" or "an example" mean that a particular feature, structure, or characteristic described in connection with the embodiment or example is included in at least one embodiment of the present invention. Thus, the phrases "one embodiment", "an embodiment", "one example" or "an example" appearing throughout the specification do not necessarily all refer to the same embodiment or example. Furthermore, the particular features, structures, or characteristics may be combined in any suitable combination and / or sub-combination in one or more embodiments or examples. In addition, those of ordinary skill in the art should understand that the diagrams provided herein are for illustrative purposes only and are not necessarily drawn to scale. The term "and / or" used herein includes any and all combinations of one or more of the associated listed items.

[0035] In the description of the present invention, the orientation or positional relationship indicated by the terms "front", "rear", "left", "right", "upper", "lower", "vertical", "horizontal", "high", "low", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the protection scope of the present invention.

[0036] Embodiment

[0037] Reference Figure 1 As shown, an embodiment of the present invention provides a circuit for detecting the influence of leakage current on the error of a current transformer. The circuit includes: an optical fiber current transformer for being connected in series with a high-voltage current transformer to be measured.

[0038] Among them, the high-voltage current transformer refers to a current transformer that generates leakage current under the rated voltage operating state. Optionally, the high-voltage current transformer is a current transformer with a rated voltage above 1 kV.

[0039] Further, the circuit includes:

[0040] A line provided with an interface for connecting to the high-voltage current transformer to be measured; and

[0041] An optical fiber current transformer disposed on the line for being connected in series with the high-voltage current transformer to be measured through the interface.

[0042] In use, the high-voltage current transformer is connected to the line through the interface of the line, and after the high-voltage current transformer is connected to the line, it is connected in series with the optical fiber current transformer.

[0043] Further, the high-voltage current transformer is a wide-frequency and wide-range current transformer.

[0044] Further, the power supply of the circuit includes a power supply that does not generate leakage current and a power supply that generates leakage current;

[0045] The power supply that generates leakage current is used to be connected in series with the optical fiber current transformer and the high-voltage current transformer to be measured to obtain the error including leakage current of the high-voltage current transformer;

[0046] The power supply that does not generate leakage current is used to be connected in series with the optical fiber current transformer and the high-voltage current transformer to be measured to obtain the error not including leakage current of the high-voltage current transformer.

[0047] The power supply that generates leakage current refers to a power supply with a voltage range within the range where leakage current is generated, such as a 10 kV power supply; the power supply that does not generate leakage current refers to a power supply with a voltage range within the range where no leakage current is generated, such as a 220 V power supply.

[0048] Specifically refer to Figure 1 As shown, on the left is the wide-frequency wide-range current transformer 2, and on the right is the optical fiber current transformer 1. The characteristics of the optical fiber current transformer are mainly used for leakage current detection.

[0049] The detection principle is as follows:

[0050] The main characteristics of the optical fiber current transformer are:

[0051] (1) Wide range, high precision, wide frequency band, fast response, and can meet the needs of measurement and protection at the same time.

[0052] (2) Fully insulated, high temperature resistant, and there is no danger of secondary open circuit.

[0053] (3) Short-circuit fault ranging to improve the reliability of the power supply system.

[0054] When a primary high voltage is applied, the leakage current I1 generated by the high voltage will flow through the secondary winding of the wide-frequency wide-range current transformer and be superimposed on the secondary current I2, thereby affecting the error of the wide-frequency wide-range current transformer; and due to the characteristics of the optical fiber such as wide range, high precision, wide frequency band, fast response, and no electromagnetic induction coupling, there is no leakage current at high voltage. Taking the optical fiber current transformer as a standard signal, the influence of the leakage current on the error of the wide-frequency wide-range current transformer can be reflected.

[0055] Thus, the circuit of this embodiment can measure whether the leakage current affects the error of the current transformer.

[0056] Refer to Figure 2 As shown, an embodiment of the present invention provides a method for detecting the influence of leakage current on the error of a current transformer, including:

[0057] S101. Connect the optical fiber current transformer in series with the high-voltage current transformer to be measured to obtain a circuit;

[0058] S102. Apply a voltage that will not generate leakage current to the circuit, and measure the current values flowing through the high-voltage current transformer and the optical fiber current transformer;

[0059] S103. Apply a voltage that will generate leakage current to the circuit, and measure the current values flowing through the high-voltage current transformer and the optical fiber current transformer.

[0060] Thus, by using the above method, the errors of the high-voltage current transformer under the conditions of having and not having leakage current can be measured respectively. Thus, the influence of the leakage current on the error can be obtained by comparing the errors under the conditions of having and not having leakage current.

[0061] Optionally, the step of applying a voltage that will not generate leakage current to the circuit and measuring the current values flowing through the high-voltage current transformer and the optical fiber current transformer includes: applying a voltage that will not generate leakage current to the circuit, measuring the current values flowing through the high-voltage current transformer and the optical fiber current transformer, and comparing to obtain the error of the high-voltage current transformer without leakage current;

[0062] The step of applying a voltage that will generate leakage current to the circuit and measuring the current values flowing through the high-voltage current transformer and the optical fiber current transformer includes: applying a voltage that will generate leakage current to the circuit, measuring the current values flowing through the high-voltage current transformer and the optical fiber current transformer, and comparing to obtain the error of the high-voltage current transformer with leakage current;

[0063] Compare the error with leakage current and the error without leakage current to obtain a difference, and this difference is the influence amount of the leakage current on the error of the high-voltage current transformer.

[0064] Further, the high-voltage current transformer to be measured is a wide-bandwidth and wide-range current transformer.

[0065] Further, the rated voltage of the wide-bandwidth and wide-range current transformer is above 1 KV.

[0066] Specifically:

[0067] When applying a voltage that does not generate leakage current, the values of the wide-bandwidth and wide-range current transformer and the optical fiber current transformer can be measured and compared to obtain the error of the wide-bandwidth and wide-range current transformer. At this time, there is no leakage current in both of them, and the obtained error will be the error without leakage current.

[0068] When applying the rated voltage that can generate leakage current, measure and compare the values of the broadband wide-range current transformer and the optical fiber current transformer again. At this time, there is still no leakage current in the secondary current of the optical fiber current transformer, while the secondary current of the broadband wide-range current transformer will contain leakage current. By comparing again, the influence of the leakage current on the error of the broadband wide-range current transformer under high voltage can be obtained.

[0069] An embodiment of the present invention provides a use of an optical fiber current transformer for detecting the influence of leakage current on the error of a current transformer.

[0070] In the embodiment of the present invention, by connecting the optical fiber current transformer in series with the high-voltage current transformer to be measured, the detection of the influence of the leakage current on the error of the high-voltage current transformer is realized; obviously, the embodiment of the present invention mainly utilizes the characteristic that there is no leakage current in the optical fiber current transformer under high voltage to realize the detection of the influence of the leakage current on the error of the high-voltage current transformer.

[0071] The specific embodiments described above further elaborate on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A circuit for detecting the influence of leakage current on the error of a current transformer, characterized in that, the circuit includes: a line provided with an interface for connecting with a high-voltage current transformer to be measured; and an optical fiber current transformer disposed on the line and used for being connected in series with the high-voltage current transformer to be measured through the interface; the high-voltage current transformer is a wide-frequency and wide-range current transformer; the power supply of the circuit includes a power supply that does not generate leakage current and a power supply that generates leakage current; the power supply that generates leakage current is used for being connected in series with the optical fiber current transformer and the high-voltage current transformer to be measured to obtain the error of the high-voltage current transformer including leakage current; the power supply that does not generate leakage current is used for being connected in series with the optical fiber current transformer and the high-voltage current transformer to be measured to obtain the error of the high-voltage current transformer without leakage current; a method for cooperating with the circuit: connect the optical fiber current transformer in series with the high-voltage current transformer to be measured to obtain a circuit; apply a voltage that does not generate leakage current to the circuit and measure the current values flowing through the high-voltage current transformer and the optical fiber current transformer; apply a voltage that generates leakage current to the circuit and measure the current values flowing through the high-voltage current transformer and the optical fiber current transformer; the step of applying a voltage that does not generate leakage current to the circuit and measuring the current values flowing through the high-voltage current transformer and the optical fiber current transformer includes: applying a voltage that does not generate leakage current to the circuit, measuring the current values flowing through the high-voltage current transformer and the optical fiber current transformer, and comparing to obtain the error of the high-voltage current transformer without leakage current; the step of applying a voltage that generates leakage current to the circuit and measuring the current values flowing through the high-voltage current transformer and the optical fiber current transformer includes: applying a voltage that generates leakage current to the circuit, measuring the current values flowing through the high-voltage current transformer and the optical fiber current transformer, and comparing to obtain the error of the high-voltage current transformer including leakage current; compare the error including leakage current with the error without leakage current to obtain a difference, and this difference is the influence amount of the leakage current on the error of the high-voltage current transformer.

2. The circuit for detecting the influence of leakage current on the error of a current transformer according to claim 1, wherein The high-voltage current transformer to be measured is a wide-frequency and wide-range current transformer.

3. A circuit for detecting the influence of leakage current on the error of a current transformer according to claim 1, characterized in that, The rated voltage of the wide-frequency and wide-range current transformer is above 1 KV.

4. A circuit for detecting the influence of leakage current on the error of a current transformer according to claim 1, characterized in that, The optical fiber current transformer is used for detecting the influence of leakage current on the error of the current transformer.

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