Mutual inductor one-point grounding monitoring system and method

Abstract

The invention relates to the technical field of electric power detection, and discloses a mutual inductor one-point grounding monitoring system and method.The monitoring system comprises an access module used for accessing a signal source to a signal injection point of a mutual inductor, and a first monitoring module used for monitoring a grounding wire current effective value in real time; the second monitoring module is used for monitoring the signal characteristics of the current signal in real time; the prediction module is used for predicting whether a line corresponding to the mutual inductor has a fault or not within a preset time period according to the current effective value and the signal waveform, if the fault is predicted to occur, calculating first fault credibility according to the current effective value, and calculating second fault credibility according to the signal characteristics; and the fault module is used for calculating comprehensive credibility according to the first credibility and the second credibility, when the comprehensive credibility is greater than a preset credibility threshold value, an early warning signal is sent, and a fault point location is judged, so that the accuracy and the sensitivity of the mutual inductor one-point grounding monitoring system for judging a multi-point grounding fault are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of power detection, and particularly to a monitoring system and method for single-point grounding of transformers. Background Art

[0002] In order to prevent the primary and secondary insulation of current and voltage transformers from being damaged or broken down, so that high voltage can jump to the secondary side, causing electric shock to personnel and damage to equipment, the secondary circuits of current and voltage transformers must have grounding points. Also, since multiple grounding points in a group of transformers may cause measurement errors under certain circumstances. Therefore, the "Highlights of Anti-Accident Measures for Relay Protection and Safety Automatic Devices" stipulates that there can be and only one grounding point in the secondary circuit of current and voltage transformers.

[0003] In the existing single-point grounding monitoring system for transformers, the multi-point grounding situation is generally judged based on the grounding current value, and then an alarm signal is sent. However, the accuracy and sensitivity of the above monitoring system for multi-point grounding faults are relatively low. Therefore, there is a need for a monitoring system and method for single-point grounding of transformers with high accuracy and sensitivity. Summary of the Invention

[0004] Aiming at the problems existing in the above-mentioned prior art, the purpose of the present invention is to provide a monitoring system and method for single-point grounding of transformers, which solves the problem that in the existing single-point grounding monitoring system for transformers, the multi-point grounding situation is generally judged based on the grounding current value, and then an alarm signal is sent, but the accuracy and sensitivity of the above monitoring system for multi-point grounding faults are relatively low.

[0005] To achieve the above purpose, the present invention provides a monitoring system and method for single-point grounding of transformers. The monitoring system includes:

[0006] An access module for accessing a signal source to a signal injection point of the transformer, and the signal source is used to inject a signal into the transformer;

[0007] A first monitoring module for real-time monitoring of the effective value of the grounding wire current;

[0008] A second monitoring module for real-time monitoring of the signal characteristics of the current signal, where the signal characteristics include signal waveform and signal path;

[0009] A prediction module for predicting whether a fault occurs in the corresponding line of the transformer within a preset period according to the current effective value and the signal waveform. If a fault is predicted, a first credibility is calculated according to the current effective value, and a second credibility is calculated according to the signal characteristics;

[0010] A failure module, configured to calculate a comprehensive credibility based on a first credibility and a second credibility. When the comprehensive credibility is greater than a preset credibility threshold, it sends a warning signal and determines the failure point.

[0011] In some embodiments of the present application, when predicting whether a failure occurs in the effective value of the current and the signal waveform within a preset time period, it includes:

[0012] The prediction module sets a preset effective current threshold and a preset waveform extreme difference threshold according to historical failure data;

[0013] The prediction module compares the effective value of the current with the preset effective current threshold. When the effective value of the current is greater than the preset effective current threshold, it predicts that a failure occurs;

[0014] The prediction module determines a first waveform extreme value and a second waveform extreme value according to the signal waveform, calculates a waveform extreme difference according to the first waveform extreme value and the second waveform extreme value, and compares the waveform extreme difference with the preset waveform extreme difference threshold. If the waveform extreme difference is greater than the preset waveform extreme difference threshold, it predicts that a failure occurs.

[0015] In some embodiments of the present application, the prediction module is pre-set with a first preset waveform extreme difference N1, a second preset waveform extreme difference N2, a third preset waveform extreme difference N3, and a fourth preset waveform extreme difference N4, and N1 < N2 < N3 < N4;

[0016] It is also set with a first preset second credibility Y1, a second preset second credibility Y2, a third preset second credibility Y3, and a fourth preset second credibility Y4, Y1 < Y2 < Y3 < Y4;

[0017] According to the calculated waveform extreme difference N0, select the corresponding second credibility according to the relationship between N0 and the first preset waveform extreme difference N1, the second preset waveform extreme difference N2, the third preset waveform extreme difference N3, and the fourth preset waveform extreme difference N4;

[0018] When N0 < N1, select the first preset second credibility Y1 as the current second credibility;

[0019] When N1 ≤ N0 < N2, select the second preset second credibility Y2 as the current second credibility;

[0020] When N2 ≤ N0 < N3, select the third preset second credibility Y3 as the current second credibility;

[0021] When N3 ≤ N0 < N4, select the fourth preset second credibility Y4 as the current second credibility.

[0022] In some embodiments of the present application, the prediction module sets a first preset current fault feature interval I01, a second preset current fault feature interval I02, …, an nth preset current fault feature interval I0n according to historical fault data, and calculates the first credibility according to the relationship between the effective current value and the preset current fault feature interval I0i;

[0023] If the effective current value is within the ith preset current fault feature interval I0i, obtain the historical fault times B and the total historical detection times B0 of the ith preset current fault feature interval I0i;

[0024] The first credibility = historical fault times B / total historical detection times B0.

[0025] In some embodiments of the present application, when the comprehensive credibility is greater than the preset credibility threshold, sending a warning signal and determining the fault location includes:

[0026] The formula for calculating the comprehensive credibility P is:

[0027] P = B / B0 + Yi;

[0028] The fault module pre-sets a preset credibility threshold Pn. When P > Pn, send a warning signal and determine the fault location;

[0029] The fault location is determined according to the signal path and impedance. The corresponding line where a fault will occur is judged according to the signal path. The line impedance is calculated according to the current value of the injected signal and the line voltage value. When the change amount of the line impedance is greater than the preset change amount, calculate the impedance difference between the current line impedance and the initial line impedance, and obtain the length prediction value of the fault location to the signal injection point according to the impedance difference.

[0030] In some embodiments of the present application, there is also provided a method for monitoring the single-point grounding of a current transformer, which is applied to the above-mentioned current transformer single-point grounding monitoring system:

[0031] Connect a signal source to the signal injection point of the current transformer;

[0032] Monitor the effective value of the grounding wire current in real time;

[0033] Monitor the signal characteristics of the current signal in real time, where the signal characteristics include signal waveform and signal path;

[0034] Predict whether a fault occurs in the corresponding line of the current transformer within a preset period according to the effective current value and the signal waveform. If a fault is predicted to occur, calculate the first credibility according to the effective current value and calculate the second credibility according to the signal characteristics;

[0035] Calculate the comprehensive credibility based on the first credibility and the second credibility. When the comprehensive credibility is greater than the preset credibility threshold, send a warning signal and determine the fault location.

[0036] In some embodiments of the present application, when predicting whether a fault occurs in the effective current value and the signal waveform within a preset time period, it includes:

[0037] Set a preset effective current threshold and a preset waveform extreme difference threshold according to historical fault data;

[0038] Compare the effective current value with the preset effective current threshold. When the effective current value is greater than the preset effective current threshold, predict that a fault occurs;

[0039] Determine a first waveform extreme value and a second waveform extreme value according to the signal waveform, calculate the waveform extreme difference according to the first waveform extreme value and the second waveform extreme value, compare the waveform extreme difference with the preset waveform extreme difference threshold. If the waveform extreme difference is greater than the preset waveform extreme difference threshold, predict that a fault occurs.

[0040] In some embodiments of the present application, a first preset waveform extreme difference N1, a second preset waveform extreme difference N2, a third preset waveform extreme difference N3, and a fourth preset waveform extreme difference N4 are preset in advance, and N1 < N2 < N3 < N4;

[0041] A first preset second credibility Y1, a second preset second credibility Y2, a third preset second credibility Y3, and a fourth preset second credibility Y4 are also set, and Y1 < Y2 < Y3 < Y4;

[0042] Select the corresponding second credibility according to the calculated waveform extreme difference N0 and the relationship between N0 and the first preset waveform extreme difference N1, the second preset waveform extreme difference N2, the third preset waveform extreme difference N3, and the fourth preset waveform extreme difference N4;

[0043] When N0 < N1, select the first preset second credibility Y1 as the current second credibility;

[0044] When N1 ≤ N0 < N2, select the second preset second credibility Y2 as the current second credibility;

[0045] When N2 ≤ N0 < N3, select the third preset second credibility Y3 as the current second credibility;

[0046] When N3 ≤ N0 < N4, select the fourth preset second credibility Y4 as the current second credibility.

[0047] In some embodiments of the present application, a first preset current fault characteristic interval I01, a second preset current fault characteristic interval I02, …, an nth preset current fault characteristic interval I0n are set according to historical fault data. According to the relationship between the effective current value and the preset current fault characteristic interval I0i, the first credibility is calculated;

[0048] If the effective current value is within the ith preset current fault characteristic interval I0i, the historical fault times B and the total historical detection times B0 of the ith preset current fault characteristic interval I0i are obtained;

[0049] The first credibility = historical fault times B / total historical detection times B0.

[0050] In some embodiments of the present application, when the comprehensive credibility is greater than the preset credibility threshold, when sending a warning signal and judging the fault location, it includes:

[0051] The formula for calculating the comprehensive credibility P is:

[0052] P = B / B0 + Yi;

[0053] A preset credibility threshold Pn is set in advance. When P > Pn, a warning signal is sent and the fault location is judged;

[0054] The fault location is judged according to the signal path and impedance. The corresponding line where the fault will occur is judged according to the signal path. The line impedance is calculated according to the current value of the injected signal and the line voltage value. When the change amount of the line impedance is greater than the preset change amount, the impedance difference between the current line impedance and the initial line impedance is calculated. According to the impedance difference, the length prediction value from the fault location to the signal injection point is obtained.

[0055] The present invention provides a mutual inductor single-point grounding monitoring system and method. Compared with the prior art, it has the following beneficial effects:

[0056] By injecting a signal to obtain the effective current value and signal characteristics, whether a fault occurs is predicted through the effective current value and signal characteristics. If a fault is predicted to occur, the comprehensive credibility is calculated. According to the comprehensive credibility, it is judged whether the prediction is accurate. If it is accurate, a warning signal is sent and the fault location is judged, realizing the precise detection of the mutual inductor single-point grounding monitoring system for multi-point grounding, sending a warning signal in advance, predicting the fault location, and greatly improving the working efficiency of the mutual inductor. Description of the Drawings

[0057] Figure 1 Shows a schematic diagram of a mutual inductor single-point grounding monitoring system in an embodiment of the present invention;

[0058] Figure 2The flowchart of a method for monitoring single-point grounding of a mutual inductor in an embodiment of the present invention is shown. Detailed implementation manners

[0059] The following further describes in detail the specific implementation manners of the present invention in conjunction with the accompanying drawings and embodiments. The following embodiments are used to illustrate the present invention, but are not used to limit the scope of the present invention.

[0060] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present application 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 a limitation to the present application.

[0061] The terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present application, unless otherwise stated, the meaning of "plurality" is two or more.

[0062] In the description of the present application, it should be noted that unless otherwise clearly defined and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific situations.

[0063] The following is a description of the preferred embodiments of the present invention in conjunction with the accompanying drawings.

[0064] As Figure 1 shown, an embodiment of the present invention discloses a mutual inductor single-point grounding monitoring system, and the monitoring system includes:

[0065] An access module, configured to access a signal source to a signal injection point of the mutual inductor, and the signal source is used to inject a signal into the mutual inductor;

[0066] A first monitoring module, configured to monitor the effective value of the grounding wire current in real time;

[0067] A second monitoring module, configured to monitor the signal characteristics of the current signal in real time, where the signal characteristics include a signal waveform and a signal path;

[0068] A prediction module, configured to predict whether a fault occurs in the corresponding line of the mutual inductor within a preset time period according to the effective current value and the signal waveform. If a fault is predicted, calculate a first credibility according to the effective current value, and calculate a fault credibility according to the signal characteristics;

[0069] A fault module, configured to calculate a comprehensive credibility according to the first credibility and the second credibility. When the comprehensive credibility is greater than a preset credibility threshold, send a warning signal and determine the fault location.

[0070] In this embodiment, the second monitoring module obtains the signal waveform and the signal path through a signal tracer, quickly finds the corresponding line when predicting the fault location according to the signal path, and predicts whether the mutual inductor has a fault by two methods of the effective current value and the signal characteristics, which greatly improves the accuracy and sensitivity of the single-point grounding monitoring system of the mutual inductor for the multi-point grounding situation.

[0071] In some embodiments of the present application, when predicting whether a fault occurs in the effective current value and the signal waveform within a preset time period, it includes:

[0072] The prediction module sets a preset effective current threshold and a preset waveform extreme difference threshold according to historical fault data;

[0073] The prediction module compares the effective current value with the preset effective current threshold. When the effective current value is greater than the preset effective current threshold, it is predicted that a fault occurs;

[0074] The prediction module determines a first waveform extreme value and a second waveform extreme value according to the signal waveform, calculates a waveform extreme difference according to the first waveform extreme value and the second waveform extreme value, and compares the waveform extreme difference with the preset waveform extreme difference threshold. If the waveform extreme difference is greater than the preset waveform extreme difference threshold, it is predicted that a fault occurs.

[0075] In this embodiment, the preset effective current threshold is set according to multiple current values in the first fifteen minutes of the historical fault data of the current mutual inductor, and the preset effective current threshold is set according to the minimum value of the multiple current values. The preset waveform extreme difference threshold is obtained by subtracting the minimum waveform value from the maximum waveform value among multiple signal waveform values in the first 15 minutes of the historical signal waveform fault data of the mutual inductor. When the effective current value is greater than the preset effective current threshold or the waveform extreme difference is greater than the preset waveform extreme difference threshold, it indicates that a multi-point grounding fault may occur in the mutual inductor after 15 minutes.

[0076] In some embodiments of the present application, the prediction module is pre-set with a first preset waveform extreme difference N1, a second preset waveform extreme difference N2, a third preset waveform extreme difference N3, and a fourth preset waveform extreme difference N4, and N1 < N2 < N3 < N4;

[0077] A first preset second credibility Y1, a second preset second credibility Y2, a third preset second credibility Y3, and a fourth preset second credibility Y4 are also set, where Y1 < Y2 < Y3 < Y4;

[0078] According to the calculated waveform extreme value difference N0, select the corresponding second credibility according to the relationship between N0 and the first preset waveform extreme value difference N1, the second preset waveform extreme value difference N2, the third preset waveform extreme value difference N3, and the fourth preset waveform extreme value difference N4;

[0079] When N0 < N1, select the first preset second credibility Y1 as the current second credibility;

[0080] When N1 ≤ N0 < N2, select the second preset second credibility Y2 as the current second credibility;

[0081] When N2 ≤ N0 < N3, select the third preset second credibility Y3 as the current second credibility;

[0082] When N3 ≤ N0 < N4, select the fourth preset second credibility Y4 as the current second credibility.

[0083] In this embodiment, the larger the waveform extreme value difference is, the greater the possibility of a fault occurring is, that is, the second credibility will be greater.

[0084] In some embodiments of the present application, the prediction module sets a first preset current fault feature interval I01, a second preset current fault feature interval I02,..., an nth preset current fault feature interval I0n according to historical fault data, and calculates the first credibility according to the relationship between the current effective value and the preset current fault feature interval I0i;

[0085] If the current effective value is in the ith preset current fault feature interval I0i, obtain the historical fault times B and the total historical detection times B0 of the ith preset current fault feature interval I0i;

[0086] The first credibility = historical fault times B / total historical detection times B0.

[0087] In this embodiment, according to the different preset current fault feature intervals where the current effective value is located, the historical fault times are also different. The first credibility is determined according to the historical fault times. The total historical detection times are certain. When the historical fault times are larger, the first credibility is larger, that is, the possibility of a fault occurring is greater.

[0088] In some embodiments of the present application, when the comprehensive credibility is greater than the preset credibility threshold, when sending a warning signal and judging the fault location, it includes:

[0089] The formula for calculating the comprehensive credibility P is as follows:

[0090] P = B / B0 + Yi;

[0091] A preset credibility threshold Pn is set for the faulty module in advance. When P > Pn, a warning signal is sent and the fault location is judged.

[0092] The fault location is judged according to the signal path and impedance. The corresponding line where the fault will occur is judged according to the signal path. The line impedance is calculated according to the current value of the injected signal and the line voltage value. When the change amount of the line impedance is greater than the preset change amount, the impedance difference between the current line impedance and the initial line impedance is calculated, and the length prediction value from the fault location to the signal injection point is obtained according to the impedance difference.

[0093] In this embodiment, the voltage value of each line is constant, a certain current signal is injected, and the impedance of each line is constant. If the change amount of the impedance is greater than the preset change amount, it indicates that there are multiple groundings on this line. The impedance is proportional to the line length. The larger the impedance, the greater the length from the fault location to the signal injection point. The length from the fault point to the signal injection point is calculated according to the impedance, signal injection point, and impedance difference in the case of single-point grounding, which greatly shortens the fault location judgment time.

[0094] In some embodiments of the present application, there is also a method for monitoring single-point grounding of a current transformer, which is applied to the above-mentioned current transformer single-point grounding monitoring system:

[0095] Step S201: Connect a signal source to the signal injection point of the current transformer;

[0096] Step S202: Monitor the effective value of the grounding wire current in real time;

[0097] Step S203: Monitor the signal characteristics of the current signal in real time, where the signal characteristics include signal waveform and signal path;

[0098] Step S204: Predict whether a fault occurs in the corresponding line of the current transformer within a preset time period according to the effective value of the current and the signal waveform. If a fault is predicted, calculate the first credibility according to the effective value of the current and calculate the second credibility according to the signal characteristics;

[0099] Step S205: Calculate the comprehensive credibility according to the first credibility and the second credibility. When the comprehensive credibility is greater than the preset credibility threshold, send a warning signal and judge the fault location.

[0100] In some embodiments of the present application, when predicting whether a fault occurs in the effective value of the current and the signal waveform within a preset time period, it includes:

[0101] Set a preset effective current threshold and a preset waveform extreme difference threshold according to historical fault data;

[0102] Compare the effective current value with the preset effective current threshold. When the effective current value is greater than the preset effective current threshold, predict a fault;

[0103] Determine a first waveform extreme value and a second waveform extreme value according to the signal waveform, calculate the waveform extreme difference according to the first waveform extreme value and the second waveform extreme value, compare the waveform extreme difference with the preset waveform extreme difference threshold. If the waveform extreme difference is greater than the preset waveform extreme difference threshold, predict a fault.

[0104] In some embodiments of the present application, a first preset waveform extreme difference N1, a second preset waveform extreme difference N2, a third preset waveform extreme difference N3, and a fourth preset waveform extreme difference N4 are preset in advance, and N1 < N2 < N3 < N4;

[0105] A first preset second credibility Y1, a second preset second credibility Y2, a third preset second credibility Y3, and a fourth preset second credibility Y4 are also preset, and Y1 < Y2 < Y3 < Y4;

[0106] According to the calculated waveform extreme difference N0, select the corresponding second credibility according to the relationship between N0 and the first preset waveform extreme difference N1, the second preset waveform extreme difference N2, the third preset waveform extreme difference N3, and the fourth preset waveform extreme difference N4;

[0107] When N0 < N1, select the first preset second credibility Y1 as the current second credibility;

[0108] When N1 ≤ N0 < N2, select the second preset second credibility Y2 as the current second credibility;

[0109] When N2 ≤ N0 < N3, select the third preset second credibility Y3 as the current second credibility;

[0110] When N3 ≤ N0 < N4, select the fourth preset second credibility Y4 as the current second credibility.

[0111] In some embodiments of the present application, a first preset current fault feature interval I01, a second preset current fault feature interval I02,..., an nth preset current fault feature interval I0n are set according to historical fault data. According to the relationship between the effective current value and the preset current fault feature interval I0i, calculate the first credibility;

[0112] If the effective current value is within the i-th preset current fault characteristic interval I0i, obtain the historical fault times B and the total historical detection times B0 of the i-th preset current fault characteristic interval I0i;

[0113] The first credibility = historical fault times B / total historical detection times B0.

[0114] In some embodiments of the present application, when the comprehensive credibility is greater than the preset credibility threshold, when sending a warning signal and judging the fault location, it includes:

[0115] The formula for calculating the comprehensive credibility P is:

[0116] P = B / B0 + Yi;

[0117] A preset credibility threshold Pn is preset. When P > Pn, a warning signal is sent and the fault location is judged;

[0118] The fault location is judged according to the signal path and impedance. According to the signal path, the corresponding line where a fault may occur is judged. The line impedance is calculated according to the current value of the injected signal and the line voltage value. When the change amount of the line impedance is greater than the preset change amount, the impedance difference between the current line impedance and the initial line impedance is calculated, and the length prediction value from the fault location to the signal injection point is obtained according to the impedance difference.

[0119] In summary, the present invention discloses a mutual inductor single-point grounding monitoring system and method. The system includes: an access module for accessing a signal source to the signal injection point of the mutual inductor, and the signal source is used to inject a signal into the mutual inductor; a first monitoring module for real-time monitoring of the effective value of the grounding wire current; a second monitoring module for real-time monitoring of the signal characteristics of the current signal, where the signal characteristics include signal waveform and signal path; a prediction module for predicting whether a fault occurs in the corresponding line of the mutual inductor within a preset period according to the effective current value and the signal waveform. If a fault is predicted to occur, calculate the first fault credibility according to the effective current value, and calculate the second fault credibility according to the signal characteristics; a fault module for calculating the comprehensive credibility according to the first credibility and the second credibility. When the comprehensive credibility is greater than the preset credibility threshold, a warning signal is sent and the fault location is judged. The present invention obtains the effective current value and signal characteristics by injecting a signal, predicts whether a fault occurs through the effective current value and signal characteristics. If a fault is predicted to occur, calculate the comprehensive credibility, and judge whether the prediction is accurate according to the comprehensive credibility. If accurate, send a warning signal and judge the fault location, realizing the precise detection of the mutual inductor single-point grounding monitoring system for multi-point grounding, and sending a warning signal in advance, predicting the fault location, greatly improving the working efficiency of the mutual inductor.

[0120] In the description of the above embodiments, specific features, structures, materials, or characteristics may be combined in any one or more embodiments or examples in a suitable manner.

[0121] Although the present invention has been described above with reference to embodiments, various improvements can be made thereto and components thereof can be replaced with equivalents without departing from the scope of the present invention. In particular, as long as there is no structural conflict, the features in the embodiments disclosed in the present invention can be combined with each other in any way, and the fact that not all the combinations are described in this specification is only for the consideration of saving space and resources. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

[0122] Those of ordinary skill in the art can understand that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A transformer single-point grounding monitoring system, characterized in that: include: An access module, used for connecting a signal source to a signal injection point of the mutual inductor, wherein the signal source is used for injecting a signal into the mutual inductor; The first monitoring module is used to monitor the effective value of the grounding wire current in real time; A second monitoring module, used for monitoring the signal characteristics of the current signal in real time, wherein the signal characteristics include a signal waveform and a signal path; A prediction module, used to predict whether a fault occurs in a line corresponding to the transformer within a preset time period according to the effective value of the current and the signal waveform, and if a fault is predicted, calculate a first credibility according to the effective value of the current and calculate a second credibility according to the signal feature; The fault module is used to calculate the comprehensive credibility according to the first credibility and the second credibility, and when the comprehensive credibility is greater than a preset credibility threshold, send a warning signal and determine the fault point.

2. The transformer single-point grounding monitoring system according to claim 1, characterized in that: Predicting whether the current effective value and the signal waveform have a fault within a preset period of time includes: The prediction module sets a preset current effective threshold and a preset waveform extreme difference threshold according to historical fault data; The prediction module compares the current effective value with the preset current effective threshold, and predicts that a fault occurs when the current effective value is greater than the preset current effective threshold; The prediction module determines a first waveform extreme value and a second waveform extreme value according to the signal waveform, calculates a waveform extreme value difference according to the first waveform extreme value and the second waveform extreme value, compares the waveform extreme value difference with a preset waveform extreme value threshold, and predicts a fault if the waveform extreme value difference is greater than the preset waveform extreme value threshold.

3. The transformer single-point grounding monitoring system according to claim 2, characterized in that: The prediction module is pre-set with a first preset waveform extreme value difference N1, a second preset waveform extreme value difference N2, a third preset waveform extreme value difference N3, and a fourth preset waveform extreme value difference N4, and N1<N2<N3<N4; A first preset second credibility Y1, a second preset second credibility Y2, a third preset second credibility Y3, and a fourth preset second credibility Y4 are also set, Y1<Y2<Y3<Y4; According to the calculated waveform extreme value difference N0, a corresponding second credibility is selected according to the relationship between N0 and the first preset waveform extreme value difference N1, the second preset waveform extreme value difference N2, the third preset waveform extreme value difference N3, and the fourth preset waveform extreme value difference N4; When N0<N1, the first preset second credibility Y1 is selected as the current second credibility; When N1≤N0<N2, the second preset second credibility Y2 is selected as the current second credibility; When N2≤N0<N3, the third preset second credibility Y3 is selected as the current second credibility; When N3≤N0<N4, the fourth preset second credibility Y4 is selected as the current second credibility.

4. The transformer single-point grounding monitoring system according to claim 3 is characterized in that: The prediction module sets a first preset current fault characteristic interval I01, a second preset current fault characteristic interval I02, ... an nth preset current fault characteristic interval I0n according to historical fault data, and calculates the first credibility according to the relationship between the current effective value and the preset current fault characteristic interval I0i; If the current effective value is in the i-th preset current fault characteristic interval I0i, the historical fault number B and the historical total detection number B0 of the i-th preset current fault characteristic interval I0i are obtained; The first credibility=historical failure times B / historical detection total times B0.

5. The transformer single-point grounding monitoring system according to claim 4, characterized in that: When the comprehensive credibility is greater than the preset credibility threshold, sending a warning signal and determining the fault point includes: The formula for calculating the comprehensive credibility P is: P = B / B0 + Yi; The fault module is pre-set with a preset credibility threshold Pn. When P>Pn, a warning signal is sent and the fault point is determined; The fault point is judged according to the signal path and impedance, and the corresponding line where the fault will occur is judged according to the signal path. The line impedance is calculated according to the current value of the injected signal and the line voltage value. When the line impedance change is greater than the preset change, the impedance difference between the current line impedance and the initial line impedance is calculated, and the length prediction value from the fault point to the signal injection point is obtained according to the impedance difference.

6. A method for monitoring a single-point grounding of a mutual inductor, applied to a single-point grounding monitoring system of a mutual inductor according to any one of claims 1 to 5, characterized in that: include: Connect the signal source to the signal injection point of the transformer; Real-time monitoring of the effective value of the ground wire current; monitoring the signal characteristics of the current signal in real time, wherein the signal characteristics include a signal waveform and a signal path; Predict whether a fault occurs in the line corresponding to the transformer within a preset time period according to the effective value of the current and the signal waveform; if a fault is predicted, calculate the first credibility according to the effective value of the current, and calculate the second credibility according to the signal characteristics; The comprehensive credibility is calculated according to the first credibility and the second credibility. When the comprehensive credibility is greater than a preset credibility threshold, an early warning signal is sent and the fault point is determined.

7. The method for monitoring single-point grounding of a transformer according to claim 6, characterized in that: Predicting whether the current effective value and the signal waveform have a fault within a preset period of time includes: Set a preset current effective threshold and a preset waveform extreme difference threshold according to historical fault data; Comparing the effective current value with the preset effective current threshold, and predicting a fault when the effective current value is greater than the preset effective current threshold; A first waveform extreme value and a second waveform extreme value are determined according to the signal waveform, a waveform extreme value difference is calculated according to the first waveform extreme value and the second waveform extreme value, the waveform extreme value difference is compared with a preset waveform extreme value threshold, and if the waveform extreme value difference is greater than the preset waveform extreme value threshold, a fault is predicted.

8. The method for monitoring single-point grounding of a mutual inductor according to claim 7, characterized in that: A first preset waveform extreme value difference N1, a second preset waveform extreme value difference N2, a third preset waveform extreme value difference N3, and a fourth preset waveform extreme value difference N4 are preset, and N1<N2<N3<N4; A first preset second credibility Y1, a second preset second credibility Y2, a third preset second credibility Y3, and a fourth preset second credibility Y4 are also set, Y1<Y2<Y3<Y4; According to the calculated waveform extreme value difference N0, a corresponding second credibility is selected according to the relationship between N0 and the first preset waveform extreme value difference N1, the second preset waveform extreme value difference N2, the third preset waveform extreme value difference N3, and the fourth preset waveform extreme value difference N4; When N0<N1, the first preset second credibility Y1 is selected as the current second credibility; When N1≤N0<N2, the second preset second credibility Y2 is selected as the current second credibility; When N2≤N0<N3, the third preset second credibility Y3 is selected as the current second credibility; When N3≤N0<N4, the fourth preset second credibility Y4 is selected as the current second credibility.

9. The method for monitoring single-point grounding of a mutual inductor according to claim 8, characterized in that: A first preset current fault characteristic interval I01, a second preset current fault characteristic interval I02, ... an nth preset current fault characteristic interval I0n are set according to historical fault data, and the first credibility is calculated according to the relationship between the current effective value and the preset current fault characteristic interval I0i; If the current effective value is in the i-th preset current fault characteristic interval I0i, the historical fault number B and the historical total detection number B0 of the i-th preset current fault characteristic interval I0i are obtained; The first credibility = the number of historical failures B / the total number of historical detections B0.

10. The method for monitoring single-point grounding of a mutual inductor according to claim 6, characterized in that: When the comprehensive credibility is greater than the preset credibility threshold, sending a warning signal and determining the fault point includes: The formula for calculating the comprehensive credibility P is: P = B / B0 + Yi; A preset credibility threshold Pn is preset. When P>Pn, an early warning signal is sent and the fault point is determined; The fault point is judged according to the signal path and impedance, and the corresponding line where the fault will occur is judged according to the signal path. The line impedance is calculated according to the current value of the injected signal and the line voltage value. When the line impedance change is greater than the preset change, the impedance difference between the current line impedance and the initial line impedance is calculated, and the length prediction value from the fault point to the signal injection point is obtained according to the impedance difference.

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