A method for detecting multi-point grounding fault of a voltage transformer secondary circuit

Abstract

The application discloses a kind of voltage transformer secondary circuit multipoint ground fault detection method, utilize multiple parallel current sampling units to carry out detection to secondary circuit, and according to detection result carries out multiple grouping detection, and according to multiple grouping data comparison carries out the judgment of voltage transformer secondary circuit grounding point, can utilize multiple parallel current sampling units to make that current dispersion, and after grouping multiple detection, can effectively avoid the generation of unbalanced current;Several current sampling units are connected in parallel on voltage transformer secondary circuit, and are grounded at the other end, so that the current sampling unit of ungrounded point can have current loop, the potential of the two ends of grounding point is close, cannot form loop, can pass through the value in current sampling unit and the value change in multiple detection, to carry out multi-angle judgment to grounding point, with accurate judgment ability to grounding point.

Description

Technical Field

[0001] This invention relates to the field of voltage transformer technology, and more particularly to a method for detecting multi-point grounding faults in the secondary circuit of a voltage transformer. Background Technology

[0002] Voltage transformers are common and important measuring devices in power systems, used to transform high-voltage systems into low-voltage signals for measurement and protection. Also known as voltage converters, voltage transformers are voltage transformation devices that convert high voltage in high-voltage or low-voltage circuits into low voltage to supply instruments and relay protection devices for measurement, metering, and protection. The working principle of a voltage transformer utilizes the principle of electromagnetic induction. Two insulated windings with different numbers of turns are wound on a closed iron core. The primary winding (N1) is connected to the power supply side, and the secondary winding (N2) is connected to the output side. When a voltage is applied to the primary winding, an alternating current flows through it, generating an alternating magnetic flux with the same frequency as the power supply in the iron core. Since the primary and secondary windings are on the same iron core, according to the law of electromagnetic induction, an induced electromotive force (EMF) with the same frequency but a different value is generated in the secondary winding.

[0003] The secondary circuit of a voltage transformer is an electrical circuit consisting of interconnected secondary devices that monitor, control, regulate, and protect the primary equipment. It is a high-impedance circuit, and the magnitude of the secondary current is determined by the circuit's impedance. When the electromotive force in the secondary circuit decreases, the secondary current increases, causing the primary current to automatically increase by a component to maintain electromagnetic balance between the primary and secondary sides.

[0004] Multi-point grounding faults refer to the presence of multiple grounding points in the secondary circuit. This can cause changes in the current loop, leading to measurement errors and protection failures. When multiple grounding points exist, current may flow into one grounding point and then out of another, resulting in measurement errors and protection failures. Therefore, detecting multi-point grounding faults in the secondary circuit of voltage transformers is of great significance.

[0005] The prior art CN113933747A discloses a voltage transformer secondary circuit grounding current detection system and method. This system utilizes components such as a data acquisition module, a transmission module, and online monitoring equipment. The data acquisition module obtains electrical and environmental parameter data, which are then converted into corresponding DC state data by the transmission module. The online monitoring equipment outputs the detection results when warning conditions are met. This solves the problems of inaccurate detection results and inability to pinpoint grounding current faults to specific windings in traditional voltage transformer secondary circuit grounding current detection devices. However, due to the mapping relationship between the DC power supply and the voltage transformer secondary circuit, unbalanced current in the data acquisition module can affect the current analysis results and the accuracy of grounding point determination.

[0006] Therefore, it is necessary to improve the existing methods for detecting multi-point grounding faults in the secondary circuit of voltage transformers in order to solve the above problems. Summary of the Invention

[0007] This invention overcomes the shortcomings of the prior art and provides a method for detecting multi-point grounding faults in the secondary circuit of a voltage transformer, aiming to solve the problem of grounding judgment errors caused by unbalanced current in the grounding detection of the secondary circuit of a voltage transformer in the prior art.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a method for detecting multi-point grounding faults in the secondary circuit of a voltage transformer, comprising the following steps:

[0009] S1: Connect several switches and current sampling units in series one by one, and connect them in parallel with the secondary circuit of the voltage transformer respectively. The other end of the lines of several switches and current sampling units is grounded, and the grounding terminal of the secondary circuit of the voltage transformer is disconnected.

[0010] S2: After the grounding terminal of the secondary circuit of the voltage transformer is removed in S1, several switches are closed, the values ​​detected by several current sampling units are recorded and sorted, and grouped according to the value. The group with the smallest total value is marked as the group to be tested. The remaining current sampling units are disconnected from the corresponding switches and connected in series with the current sampling units in the group to be tested.

[0011] S3: In S2, the current sampling units of the group to be tested are recorded again, and the results of the second detection are analyzed, sorted according to the numerical values, and grouped for detection according to the grouping method in S2.

[0012] S4: Perform multiple tests on the groups in S3 until the current sampling unit value on the last one or more secondary circuit intersection branches does not decrease by a factor of 1, and determine the corresponding secondary circuit connection point as the grounding point.

[0013] In a preferred embodiment of the present invention, in S1, the impedances of the plurality of current sampling units are all the same.

[0014] In a preferred embodiment of the present invention, in step S2, a binary search method is used to group the data into two test groups, which are sorted according to their numerical values.

[0015] In a preferred embodiment of the present invention, in step S2, when the number of current sampling units is odd in the group with the smaller total detection value, the current sampling unit with the smallest value in another group is merged into this group.

[0016] In a preferred embodiment of the present invention, in step S3, when analyzing the secondary detection data, the secondary detection data is compared with the detection data in step S2, and grouped according to the decrease in value.

[0017] In a preferred embodiment of the present invention, in step S4, the data of the voltage transformer secondary circuit connection point corresponding to the current sampling unit that is determined to be a grounding point is compared with the data of its adjacent current sampling units, and the calculation is performed based on the data change trend.

[0018] To achieve the above objectives, the second technical solution adopted by the present invention is as follows: a method for detecting multi-point grounding faults in the secondary circuit of a voltage transformer, comprising: a switching unit, and a sampling unit disposed on the switching unit;

[0019] The switching unit includes a plurality of switches, and the sampling unit includes a plurality of current sampling units. The number of the plurality of switches is consistent with the number of the plurality of current sampling units, and they correspond one-to-one.

[0020] The two ends of the switching unit are respectively connected to the secondary circuit of the voltage transformer and the sampling unit. A plurality of the switches are evenly distributed on the secondary circuit of the voltage transformer and connected in parallel. The other end of the plurality of current sampling units is grounded.

[0021] Several current sampling units are respectively connected to a data processor, which is equipped with a control system. The control system controls the closing of several switches, and the secondary circuit of the voltage transformer is de-grounded before being connected to the several switches.

[0022] In a preferred embodiment of the present invention, the number of the plurality of current sampling units is a power of 2.

[0023] In a preferred embodiment of the present invention, a plurality of current sampling units are used to detect the magnitude of the grounding current on the secondary circuit of the voltage transformer, and the range of the plurality of current sampling units is matched with the electromotive force of the secondary circuit.

[0024] In a preferred embodiment of the present invention, the data processor is capable of recording and processing the current magnitude on the plurality of current sampling units, and transmitting the control signal to the control system according to the current magnitude. The control system controls the closing of the plurality of switches respectively, thereby realizing the on / off state of the plurality of current sampling units.

[0025] This invention addresses the shortcomings of the prior art and has the following beneficial effects:

[0026] (1) This invention provides a method for detecting multiple grounding faults in the secondary circuit of a voltage transformer. It uses multiple parallel current sampling units to detect the secondary circuit, performs multiple group detections based on the detection results, and determines the grounding point of the secondary circuit of the voltage transformer based on the comparison of the data from the multiple groups. Compared with the existing method for detecting multiple grounding faults in the secondary circuit of a voltage transformer, this method can use multiple parallel current sampling units to disperse the current passing through the circuit, and can effectively avoid the generation of unbalanced current after multiple group detections.

[0027] (2) In this invention, the impedance of several current sampling units is the same. When comparing the data of multiple group detections, the grounding point can be judged by reducing the value of several current sampling units. Compared with the prior art, the grounding point and non-grounding point can be distinguished by reducing the data, which has high accuracy for grounding current and can improve the detection accuracy of the grounding point of the secondary circuit of the voltage transformer.

[0028] (3) In this invention, several current sampling units are connected in parallel to the secondary circuit of the voltage transformer and grounded at the other end, so that the current sampling units without grounding can have a current loop passing through. The potentials at both ends of the grounding point are close and cannot form a loop. Compared with the prior art, the docking point can be judged from multiple angles by comparing the magnitude of the values ​​in the current sampling units and the changes in the values ​​in multiple sets of detections, and has the ability to accurately judge the docking point.

[0029] (4) In this invention, the number of current sampling units is a power of 2, so that in the process of multiple group detections, the number of current sampling units in each group after each group detection is always consistent. Compared with the prior art, it can reduce the data in the data comparison after grouping to strictly meet the multiple relationship, and can effectively distinguish the data of the docking location. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a flowchart of a preferred embodiment of the present invention;

[0032] Figure 2 This is a structural diagram of a grounding mounting base according to a preferred embodiment of the present invention. Detailed Implementation

[0033] 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.

[0034] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein. Therefore, the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0035] like Figure 1 As shown, a method for detecting multi-point grounding faults in the secondary circuit of a voltage transformer includes the following steps:

[0036] S1: Connect several switches and current sampling units in series, and connect them in parallel with the secondary circuit of the voltage transformer. Ground the other end of the circuit of the several switches and current sampling units, and disconnect the grounding terminal of the secondary circuit of the voltage transformer.

[0037] S2: After the grounding terminal of the secondary circuit of the voltage transformer in S1 is removed, several switches are closed, the values ​​detected on several current sampling units are recorded and sorted, and grouped according to the value. The group with the smallest total value is marked as the group to be tested. The switches corresponding to the remaining current sampling units are opened and connected in series with the current sampling units in the group to be tested.

[0038] S3: In S2, several current sampling units of the group to be tested are recorded again, and the results of the secondary test are analyzed and sorted according to the value. The grouping test is carried out according to the grouping method in S2. Several current sampling units are connected in parallel to the secondary circuit of the voltage transformer and grounded at the other end, so that the current sampling units without grounding can have a current loop. The potentials at both ends of the grounding point are close and cannot form a loop. By comparing the value of the current sampling units and the value changes in multiple groups of tests, the docking point can be judged from multiple angles, and the docking point can be accurately judged.

[0039] S4: Perform multiple tests on the groups in S3 until the current sampling unit values ​​on the last one or more secondary circuit intersection branches do not decrease by a factor of two, and determine the voltage transformer secondary circuit connection point corresponding to the current sampling unit that does not decrease by a factor of two as the grounding point.

[0040] Preferably, after multiple current sampling units are connected in parallel to the secondary circuit of the voltage transformer, a load resistor is connected in series in the circuit branch of each current sampling unit to prevent excessive current from damaging the current sampling unit.

[0041] By using multiple parallel current sampling units to detect the secondary circuit, and performing multiple group tests based on the detection results, the grounding point of the voltage transformer's secondary circuit is determined by comparing the data from multiple group tests. This method can disperse the current passing through the circuit using multiple parallel current sampling units, and effectively avoid the generation of unbalanced current after multiple group tests.

[0042] In S1, the impedances of several current sampling units are all the same. Because the impedances of these multiple current sampling units are identical, when comparing data from multiple group detections, the grounding point can be determined by reducing the multiplier based on the values ​​of the several current sampling units. This allows for the differentiation between grounding and ungrounded points, providing high accuracy for grounding current detection and improving the accuracy of detecting grounding points in the secondary circuit of voltage transformers.

[0043] In S3, when analyzing the secondary detection data, the secondary detection data is compared with the detection data in S2, and grouped according to the decrease in value. In multiple groupings, because the number of current sampling units and the total impedance of the groups are inconsistent, the current in the current sampling units will also change according to the total capacitive reactance of the circuits before and after.

[0044] To achieve the above objectives, the second technical solution adopted by the present invention is: a method for detecting multi-point grounding faults in the secondary circuit of a voltage transformer, comprising: a switching unit and a sampling unit disposed on the switching unit.

[0045] The switching unit contains several switches, and the sampling unit contains several current sampling units. The number of switches is the same as the number of current sampling units, and they correspond one-to-one.

[0046] The two ends of the switching unit are connected to the secondary circuit of the voltage transformer and the sampling unit, respectively. Several switches are evenly distributed on the secondary circuit of the voltage transformer and connected in parallel. The other end of several current sampling units is grounded. Each switch and each current sampling unit constitutes a branch, which detects the current at a point on the secondary circuit of the voltage transformer and obtains the potential at the intersection point of the current sampling unit and the secondary circuit of the voltage transformer by measuring the current of the current sampling unit.

[0047] Several current sampling units are connected to a data processor, which is equipped with a control system. The control system controls the closing of several switches, and the secondary circuit of the voltage transformer is de-grounded before being connected to the switches.

[0048] The number of current sampling units is a power of 2. This ensures that, during multiple group detections, the number of current sampling units in each group remains consistent after each grouping. This allows for data comparison after grouping, ensuring that the data is reduced to a strict multiple relationship and enabling effective differentiation of data from different locations.

[0049] Several current sampling units are used to detect the magnitude of the grounding current in the secondary circuit of the voltage transformer. The range of these current sampling units is matched to the electromotive force of the secondary circuit. The range and accuracy of the current sampling units must be matched to the secondary circuit of the voltage transformer to meet the range and accuracy requirements of current changes in the preceding and following groups.

[0050] The data processor can record and process the current magnitudes of several current sampling units, and send control signals to the control system based on the current magnitudes. The control system then controls the opening and closing of several switches to achieve the on / off state of the current sampling units. Each current sampling unit includes components such as a current sensor, a current sampling circuit, and a microcontroller or digital signal processor. It can acquire current data, convert circuit signals into digital signals, and use the numerical value of the digital signal to indicate the current intensity in the circuit.

[0051] Example 1

[0052] In S2, a binary search method is used for grouping, sorting the data according to its numerical value to form two test groups. Binary search is a data grouping method, also known as binary search. Its principle is to determine the location of the target data by progressively dividing the data into two parts and comparing them within an ordered data sequence.

[0053] The advantage of binary search lies in its efficiency, because each comparison halves the amount of data to be searched, thus greatly reducing the search time. This method is helpful for searching and grouping ordered data.

[0054] After grouping the current sampling unit detection data using the binary method, the number of current sampling units in each group is the same, and the impedance of each current sampling unit is the same. It can be clearly determined that the current is reduced to half of its original value after grouping and detection.

[0055] Example 2

[0056] In S2, within the group with the smaller total detection value, if the number of current sampling units is odd, the current sampling unit with the smallest value from another group is merged into this group. This ensures that the number of current sampling units in the test group remains even, so that when regrouping, the number of current sampling units after grouping is the same.

[0057] Example 3

[0058] In step S4, the data of the voltage transformer secondary circuit connection point corresponding to the current sampling unit identified as a grounding point is compared with the data of its adjacent current sampling units, and the calculation is performed by observing the data change trend. The data of adjacent current sampling units may be smaller than the values ​​of other ungrounded points due to the influence of the grounding point. By checking whether the data of the connection points on both sides of the grounding point have a gradually decreasing trend, a basis for verifying the grounding point is provided.

[0059] Example 4

[0060] like Figure 2 As shown, a grounding base is provided on the current sampling unit, and the grounding base is located below the current sampling unit. The number of grounding bases is the same as the number of current sampling units, and they correspond one-to-one. The current sampling unit is provided with a T-shaped groove, and the grounding base is provided with a T-shaped protrusion. The T-shaped groove and the T-shaped protrusion match in shape, and the current sampling unit and the grounding base are detachably connected through the T-shaped groove and the T-shaped protrusion.

[0061] Both the current sampling unit and the grounding base have a through hole for the cable to pass through and facilitate grounding. Adjacent through holes are located on the same vertical line and coaxially. The grounding base has a clamping block that clamps and secures the cable. The clamping block is located directly below the through hole on the grounding base and is connected to the grounding base via a gear transmission structure. The gear transmission structure has a drive rod; rotation of the drive rod drives the gear transmission structure, causing the clamping block to retract and clamp the cable. In use, first fix the current sampling unit above the grounding base. Extend the cable to be grounded through the through hole on the current sampling unit and pass it through the through hole on the grounding base. After grounding the cable, adjust the cable tension. Rotating the drive rod retracts the clamping block, clamping the cable and completing the grounding and securing process.

[0062] Based on the preferred embodiments of the present invention described above, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A method for detecting multi-point grounding faults in the secondary circuit of a voltage transformer, characterized in that, Includes the following steps: S1: Connect several switches and current sampling units in series, and connect them in parallel with the secondary circuit of the voltage transformer. The other end of the circuits of the several switches and the current sampling units is grounded, and the grounding terminal of the secondary circuit of the voltage transformer is disconnected. The impedance of the current sampling units is the same. S2: After the grounding terminal of the secondary circuit of the voltage transformer is removed in S1, several switches are closed, the values ​​detected by several current sampling units are recorded and sorted, and grouped according to the value. The group with the smallest total value is marked as the group to be tested. The remaining current sampling units are disconnected from the corresponding switches and connected in series with the current sampling units in the group to be tested. S3: In S2, the current sampling units of the group to be tested are recorded again, and the results of the second detection are analyzed, sorted according to the numerical values, and grouped for detection according to the grouping method in S2. S4: Perform multiple tests on the groups in S3 until the current sampling unit value on the last one or more secondary circuit intersection branches does not decrease by a factor of 1, and determine the corresponding secondary circuit connection point as the grounding point.

2. The method for detecting multi-point grounding faults in the secondary circuit of a voltage transformer according to claim 1, characterized in that: In S2, a binary search method is used to group the data into two test groups, which are sorted according to their numerical values.

3. The method for detecting multi-point grounding faults in the secondary circuit of a voltage transformer according to claim 2, characterized in that: In S2, when the number of current sampling units is odd in the group with the smaller total detection value, the current sampling unit with the smallest value in another group is merged into this group.

4. The method for detecting multi-point grounding faults in the secondary circuit of a voltage transformer according to claim 1, characterized in that: In step S3, when analyzing the secondary detection data, the secondary detection data is compared with the detection data in step S2, and grouped according to the decrease in value.

5. The method for detecting multi-point grounding faults in the secondary circuit of a voltage transformer according to claim 1, characterized in that: In step S4, the data of the voltage transformer secondary circuit connection point corresponding to the current sampling unit that is determined to be a grounding point is compared with the data of its adjacent current sampling units, and the calculation is performed based on the data change trend.

6. A structural system for a method of detecting multi-point grounding faults in the secondary circuit of a voltage transformer, based on any one of the methods for detecting multi-point grounding faults in the secondary circuit of a voltage transformer according to claims 1-5, comprising: A switching unit, and a sampling unit disposed on the switching unit, characterized in that: The switching unit includes a plurality of switches, and the sampling unit includes a plurality of current sampling units. The number of the plurality of switches is consistent with the number of the plurality of current sampling units, and they correspond one-to-one. The two ends of the switching unit are respectively connected to the secondary circuit of the voltage transformer and the sampling unit. A plurality of the switches are evenly distributed on the secondary circuit of the voltage transformer and connected in parallel. The other end of the plurality of current sampling units is grounded. Several current sampling units are respectively connected to a data processor, which is equipped with a control system. The control system controls the closing of several switches, and the secondary circuit of the voltage transformer is de-grounded before being connected to the several switches.

7. The structural system of the method for detecting multi-point grounding faults in the secondary circuit of a voltage transformer according to claim 6, characterized in that: The number of the aforementioned current sampling units is a power of 2.

8. The structural system of the method for detecting multi-point grounding faults in the secondary circuit of a voltage transformer according to claim 6, characterized in that: Several current sampling units are used to detect the magnitude of the grounding current on the secondary circuit of the voltage transformer, and the range of several current sampling units is matched with the electromotive force of the secondary circuit.

9. The structural system of the method for detecting multi-point grounding faults in the secondary circuit of a voltage transformer according to claim 6, characterized in that: The data processor can record and process the current magnitude of the current sampling units, and send the control signal to the control system according to the current magnitude. The control system controls the closing of the switches respectively to realize the on / off circuit of the current sampling units.

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