Self-calibration device for Rogowski coil current sensor

Abstract

This invention provides a self-calibration device for a Rogowski coil current sensor, comprising: a body for detecting current signals; a shielding shell covering the body, with multiple points of equal size evenly distributed on the outer surface of the shielding shell; a current source electrically connected to the points via cables, used to inject current into the shielding shell through the cables; and a test terminal for acquiring the gain of the Rogowski coil current sensor after the injected current and performing self-calibration of the Rogowski coil current sensor based on the gain. This invention injects the test signal from the current source into the shielding shell of the current sensor through multiple cables, putting the current sensor into an online testing state. This overcomes the influence of cable position on the sensor's measurement signal and eliminates the need to consider on-site wiring and rain / corrosion protection issues, avoiding the influence of the primary system on the calibration current, thereby improving the accuracy and reliability of the current sensor in actual field use.

Description

Technical Field

[0001] This invention relates to the field of electrical technology, and more specifically to a self-calibration device for a Rogowski coil type current sensor. Background Technology

[0002] With the rapid development of high-voltage power transmission projects, large-capacity laboratories, power transmission and distribution network measurement and protection, industrial and mining enterprises, etc. have increasingly higher requirements for the accurate measurement of power frequency high current. As a major tool for measuring power frequency high current, the calibration of the Rogowski coil for its measurement accuracy and linearity has become very necessary.

[0003] During use, strong magnetic interference and changes in temperature and humidity in the environment can cause changes in the zero-point offset voltage and sensitivity of current sensors based on Rogowski coils. Even if error adjustment is performed using the parameters integrated during sensor assembly, there is still a high probability that the error will exceed the allowable range. In this case, it is necessary to obtain new error adjustment parameters and update them in the sensor to control the sensor error within the allowable range.

[0004] In related technologies, the field calibration of Rogowski coils is achieved by passing the cable through the sensor. This method does not take into account the influence of the position of the cable passing through the sensor on the signal measured by the sensor. On the other hand, the wiring of the external cable in the field environment and how to prevent rain and corrosion are difficult problems. Moreover, the calibration current is greatly affected by the primary system. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention proposes a self-calibration device for a Rogowski coil-type current sensor.

[0006] The technical solution adopted in this invention is as follows:

[0007] An embodiment of the present invention provides a self-calibration device for a Rogowski coil current sensor, comprising: a body for detecting a current signal; a shielding shell covering the body, with multiple points evenly distributed on the outer surface of the shielding shell; a current source electrically connected to the points via a cable, the current source being used to inject current into the shielding shell through the cable; and a test terminal for acquiring the gain of the Rogowski coil current sensor after the injected current, and performing self-calibration of the Rogowski coil current sensor based on the gain.

[0008] The self-calibration device for the Rogowski coil current sensor proposed in this invention may also have the following additional technical features:

[0009] According to one embodiment of the present invention, the shielding shell has a C-shaped cross-section. The air gap of the C-shaped shielding shell is at the outer edge.

[0010] According to one embodiment of the present invention, the point is connected to the cable by welding.

[0011] According to one embodiment of the present invention, the number of sockets is 2-8, preferably 4 or 5.

[0012] According to one embodiment of the present invention, the gain of the Rogowski coil current sensor after the injected current is obtained specifically according to the following formula: G = 20 * lg(U o / I1); where G is the gain, U0 is the voltage signal amplitude output by the Rogowski coil current sensor, and I1 is the amplitude of the current output by the current source.

[0013] The beneficial effects of this invention are:

[0014] This invention injects the test signal of the current source into the shielded shell of the current sensor through multiple cables, enabling the current sensor to enter the online testing state. The multiple cables can avoid the uneven current distribution caused by injecting current through a single cable. This invention overcomes the influence of cable position on the sensor measurement signal, eliminates the influence of the primary system on the calibration current, and eliminates the need to consider on-site wiring and rain and corrosion prevention issues. Therefore, it improves the accuracy and reliability of the current sensor in actual field use. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the self-calibration device based on the Rogowski coil current sensor.

[0016] Figure 2 This is a three-dimensional structural schematic diagram of a shielding shell according to an embodiment of the present invention;

[0017] Figure 3 This is a cross-sectional schematic diagram of a shielding shell according to an embodiment of the present invention. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Figure 1 This is a structural diagram of a self-calibration device based on a Rogowski coil current sensor, such as... Figure 1 As shown, the self-calibration device includes: a main body, a shielded shell 1, a current source 2, and a test terminal 3.

[0020] The main body is used to detect current signals; the shielded shell 1 houses the main body, and multiple points 4 are distributed at equal intervals on the outer surface of the shielded shell 1. The current source 2 is electrically connected to the points 4 through the cable 5. The current source 2 is used to inject current into the shielded shell 1 through the cable 5. The test terminal 3 is used to obtain the gain G of the Rogowski coil current sensor after the injected current, and to perform self-calibration of the Rogowski coil current sensor based on the gain G.

[0021] Furthermore, in one embodiment of the present invention, the gain (1) of the Rogowski coil current sensor after the injected current is obtained specifically according to the following formula:

[0022] G = 20 * lg(U) o / I1) (1);

[0023] Where G is the gain, U0 is the amplitude of the voltage signal output by the Rogowski coil current sensor, and I1 is the amplitude of the current output by the current source.

[0024] Specifically, the relationship between the output voltage signal of the Rogowski coil current sensor and the measured current is only related to the frequency of the measured current. As long as the frequency of the measured current remains unchanged, the relationship between the sensor output voltage signal and the measured current remains unchanged regardless of the amplitude. Based on relevant experiments and derivations, the specific relationship can be found in the above formula (1). The sensor will have its corresponding gain G pre-stored before it is put into use.

[0025] like Figure 1 As shown, the shielded housing 1 serves as the excitation coil. Multiple points 4 of equal size are evenly distributed on the outer surface of the Rogowski coil current sensor housing with the shielded housing 1. These points 4 are electrically connected to the cable 5 via welding. Before actual use of the current sensor, the control current source 2 injects current into the shielded housing 1 through the cable 5, putting the current sensor into a calibration state. During the calibration process, the injected current (I1) remains constant, while the frequency varies at fixed intervals. The calibration is based on the voltage signal amplitude U output by the Rogowski coil current sensor. o Using the formula (1) above, the gain G of the Rogowski coil current sensor corresponding to different frequencies is calculated and recorded sequentially to form a calibration curve. The calibration is then completed by updating the gain G (or calibration curve) of the Rogowski coil current sensor corresponding to different frequencies into the current sensor. After calibration, the current sensor can be used for online monitoring in the field. When the current sensor monitors the current, the measured current signal is obtained according to the updated (calibrated) gain G.

[0026] This enables live calibration of the current sensor, allowing for error verification and data monitoring without power interruption. This achieves on-site calibration of the current sensor, improving the accuracy and reliability of measurements taken in actual field use.

[0027] In one embodiment of the present invention, the three-dimensional structure of the shielding shell is shown below. Figure 2 As shown, the cross-section of the shielding enclosure can be seen in [reference needed]. Figure 3 There is an air gap along the circumference on the outer wall, which makes the cross-section of the shielding shell 1 C-shaped, which can effectively shield external interference signals.

[0028] In one embodiment of the present invention, point 4 and cable 5 are connected together by welding, which can effectively prevent the cable from accidentally falling off.

[0029] In one embodiment of the present invention, the number of points 4 can be 2-8, for example, the number of points 4 can be 4 or 5.

[0030] It is understandable that the current sensor operating in the field is located near an instrument box. The cable of this invention is led to the instrument box through the inside of the shielded housing, and all wiring is completed in the instrument box. Therefore, there is no need to consider the field wiring and the issues of rain and rust prevention.

[0031] In summary, the self-calibration device for the Rogowski coil current sensor according to embodiments of the present invention injects the test signal of the current source into the shielded housing of the current sensor through multiple cables, enabling the current sensor to enter the online testing state. The multiple cables can avoid uneven current distribution caused by the injection of current through a single cable. The present invention overcomes the influence of cable position on the sensor measurement signal, eliminates the influence of the primary system on the calibration current, and eliminates the need to consider on-site wiring and rain and corrosion prevention issues, thereby improving the accuracy and reliability of the current sensor in actual field use.

[0032] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Furthermore, those skilled in the art can combine and integrate the different embodiments or examples and features of different embodiments or examples described in this specification without contradiction. Furthermore, those skilled in the art can combine and integrate the different embodiments or examples described herein, as well as the features of the different embodiments or examples, without contradiction.

[0033] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0034] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0035] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A self-calibration device for a Rogowski coil type current sensor, characterized in that, include: Body, the body being used to detect current signals; A shielding shell covers the main body, and multiple points are evenly distributed on the outer surface of the shielding shell, with the number of points being 2-8. A current source, which is connected to the point power via a cable, is used to inject current into the shielding shell through the cable; A test terminal is used to obtain the gain of the Rogowski coil current sensor after the injection current is applied, and to perform self-calibration of the Rogowski coil current sensor based on the gain.

2. The self-calibration device for the Rogowski coil type current sensor according to claim 1, characterized in that, The shielding shell has a C-shaped cross-section, and the air gap of the C-shaped shielding shell is at the outer edge.

3. The self-calibration device for the Rogowski coil type current sensor according to claim 1, characterized in that, The point is connected to the cable by welding.

4. The self-calibration device for the Rogowski coil type current sensor according to claim 1, characterized in that, The number of points is 4 or 5.

5. The self-calibration device for the Rogowski coil type current sensor according to claim 1, characterized in that, Specifically, the gain of the Rogowski coil current sensor after the injected current is obtained according to the following formula: ； Where G is the gain. U 0 This refers to the amplitude of the voltage signal output by the Rogowski coil current sensor. I 1 This represents the amplitude of the output current from the current source.

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