Cable AI Fault Warning System

Abstract

The present invention discloses a cable AI fault warning system, which relates to the technical field of cable monitoring, and includes a monitoring center. The monitoring center determines whether there is an abnormality in the operation state of an electric power network through a zero-sequence voltage value of a busbar obtained by a data acquisition terminal installed on a three-phase integrated contactor. When it is determined that there is an abnormality in the operation state of the electric power network, a low-frequency voltage signal is injected into the electric power network. After the injection of the low-frequency voltage signal is completed, the monitoring center controls the three-phase integrated contactor to open the gate, and sets multi-node phase detection for cables with abnormal insulation state through low-frequency pulse current, so that when the insulation state of the cable is abnormal, the location of the cable section causing the abnormal insulation state can be further determined, thereby improving the efficiency of daily maintenance of the cable.

Description

Technical Field

[0001] The present invention relates to the technical field of cable monitoring, and in particular to a cable AI fault early warning system. Background Art

[0002] Since most cables are laid underground, laying cables in underground trenches is dark and humid all year round, so the insulation performance of the cables is very high. Early detection of the insulation performance of the cables can effectively prevent accidents.

[0003] The existing detection of the insulation performance of the cable can only roughly determine whether the insulation state of the cable is abnormal, but the location causing the abnormal insulation state cannot be determined, thus affecting the daily maintenance efficiency of the cable. How to quickly determine the location that causes the insulation state of the cable when the insulation state of the cable is abnormal is a problem we need to solve. For this purpose, we now provide a cable AI fault warning system. Summary of the invention

[0004] The object of the present invention is to provide a cable AI fault early warning system.

[0005] The object of the present invention can be achieved by the following technical solutions: A cable AI fault warning system includes a monitoring center, wherein the monitoring center is communicatively connected with a data acquisition module, a data processing module, a data analysis module and a fault warning module;

[0006] The data acquisition module is composed of several data acquisition terminals, which are installed at the connection between the branch line and the busbar and on the three-phase integrated contactor. A data acquisition terminal is also installed at the end of the branch line to obtain circuit information of the cable during use. The zero-sequence voltage value of the busbar is obtained through the data acquisition terminal installed on the three-phase integrated contactor, and the zero-sequence voltage value is sent to the monitoring center, and the monitoring center determines the operating status of the power network according to the obtained zero-sequence voltage value;

[0007] When it is determined that the operation status of the power network is abnormal, a low-frequency voltage signal is injected into the power network. After the injection of the low-frequency voltage signal is completed, the monitoring center controls the three-phase integrated contactor to open the gate;

[0008] The operation detection data of the corresponding cable is obtained through the data acquisition terminal installed at the connection between the branch line and the busbar, and the obtained operation detection data is processed by the data processing module. The data analysis module is used to analyze the insulation state of the cable according to the processing result of the data processing module, and determine whether the insulation state of the cable is normal. If it is abnormal, a fault detection instruction is generated. The fault warning module detects the cable with abnormal insulation state according to the fault detection instruction, and determines the cable segment that causes the abnormal insulation state of the cable.

[0009] Furthermore, the data acquisition terminal obtains the zero-sequence voltage value of the busbar periodically, that is, the zero-sequence voltage value of the busbar is obtained once through the data acquisition terminal at every time interval T.

[0010] Furthermore, the monitoring center's judgment process of the operation status of the power network includes:

[0011] When the zero-sequence voltage value is greater than 0, the cycle of the data acquisition terminal acquiring the bus zero-sequence voltage value is adjusted, and the zero-sequence voltages of m groups of buses are continuously acquired;

[0012] The zero-sequence voltage values ​​of m groups of buses are continuously acquired, the zero-sequence voltage values ​​of each group of buses are sequentially sorted according to the time sequence of acquisition, and it is determined whether there is an abnormality in the operation state of the power network.

[0013] Furthermore, the process of obtaining the running detection data includes:

[0014] The low-frequency input current of each branch line is acquired through the data acquisition terminal at the connection between each branch line and the busbar, and the frequency and voltage value of the low-frequency voltage signal injected into the power network are obtained.

[0015] Furthermore, the low-frequency input current generated by the injected low-frequency voltage signal is in the microampere level, and a terminal buffer is provided in each data acquisition terminal, and the terminal buffer is used to cache the low-frequency input current generated by the low-frequency voltage signal.

[0016] Furthermore, the data processing module processes the operation detection data including:

[0017] According to the voltage value of the low-frequency voltage signal and the frequency of the low-frequency voltage signal obtained by the data acquisition terminal at the connection between the branch line and the busbar, the theoretical leakage current value of the cable corresponding to the data acquisition terminal is obtained, and then the actual leakage current value of the corresponding cable is obtained through the data acquisition terminal.

[0018] Furthermore, the process of the fault warning module detecting the cable with abnormal insulation state includes:

[0019] When receiving the fault detection command, the data acquisition terminal installed at the connection between the branch line and the busbar generates a low-frequency pulse current;

[0020] Equidistant detection nodes are set on the corresponding cables, the cables are divided into several cable segments, and then low-frequency pulse current is injected into the corresponding cables;

[0021] The cable is tested in phases by using a megohmmeter to obtain the leakage current value of the corresponding phase of each detection node, and the current difference between the leakage current value and the current value of the low-frequency pulse current;

[0022] A current difference change dot graph is generated according to the current difference of each node of the three-phase cable, a warning interval is set in the current difference change dot graph, and a warning span time period is set according to the frequency of the low-frequency pulse current; the intersection area formed by the warning span time period and the warning interval is marked, and the number of current difference points in the intersection area is obtained, and whether the insulation resistance of the corresponding cable segment is normal is judged according to the number of current difference points in the obtained intersection area.

[0023] Furthermore, the warning span time period is composed of two time vertical axes, which respectively represent corresponding moments, and the corresponding moments represented are the current moment and the initial moment with an interval of t, and the time vertical axis represented by the initial moment is located before the time vertical axis represented by the current moment.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows: the monitoring center determines whether there is any abnormality in the operating state of the power network through the zero-sequence voltage value of the bus obtained by the data acquisition terminal installed on the three-phase integrated contactor. When it is determined that there is any abnormality in the operating state of the power network, a low-frequency voltage signal is injected into the power network. After the injection of the low-frequency voltage signal is completed, the monitoring center controls the three-phase integrated contactor to open the switch, and sets multi-node phase detection for the cable with abnormal insulation state through low-frequency pulse current, so that when the insulation state of the cable is abnormal, the location of the cable section that causes the abnormal insulation state can be further determined, thereby improving the efficiency of daily maintenance of the cable. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the present invention. DETAILED DESCRIPTION

[0026] like Figure 1 As shown, the cable AI fault warning system includes a monitoring center, and the monitoring center is communicatively connected with a data acquisition module, a data processing module, a data analysis module and a fault warning module;

[0027] In the specific implementation process, a power network is composed of several cables, and the cables include a busbar and a branch line connected to the busbar, and the busbar is connected to a three-phase contactor; the data acquisition module is composed of several data acquisition terminals, and the data acquisition terminals are installed at the connection between the branch line and the busbar and on the three-phase contactor, and a data acquisition terminal is also installed at the end of the branch line, which is used to obtain circuit information of the cable during use, and obtain the zero-sequence voltage value of the busbar through the data acquisition terminal installed on the three-phase contactor, and mark the zero-sequence voltage value LD; it should be further explained that in the specific implementation process, the data acquisition terminal obtains the zero-sequence voltage value of the busbar in a periodic manner, that is, every T time interval, the zero-sequence voltage value of the busbar is obtained once through the data acquisition terminal, and the zero-sequence voltage value is sent to the monitoring center, and the monitoring center determines the operating status of the power network according to the obtained zero-sequence voltage value;

[0028] It should be further explained that, in the specific implementation process, the monitoring center's judgment process of the operating status of the power network specifically includes:

[0029] When the zero-sequence voltage value LD>0, the cycle of the data acquisition terminal obtaining the bus zero-sequence voltage value is adjusted to T / m, and the zero-sequence voltage of m groups of buses is continuously obtained, where m>4 and m is an integer;

[0030] The zero-sequence voltage values ​​of m groups of buses are obtained continuously, and the zero-sequence voltage value of each group of buses is marked as TD i , the zero-sequence voltage values ​​of each group of buses are sequentially sorted according to the time sequence in which they are obtained, where i=1, 2, ..., m;

[0031] Where TD i The zero-sequence voltage value ≠0 is marked. When the following conditions are met, it is determined that the operation status of the power network is abnormal:

[0032] When there is a continuously acquired zero-sequence voltage value among the marked zero-sequence voltage values, it is determined that the operation state of the power network is abnormal; it should be further explained that, in the specific implementation process, the number of continuously acquired zero-sequence voltage groups is at least two groups;

[0033] When there is no continuously collected zero-sequence voltage value in the marked zero-sequence voltage value, the marked zero-sequence voltage value TD is obtained. i ≠0, and mark the number as k, where k≤m and k is an integer;

[0034] A percentage threshold a is set, and when k / m≥a, it is determined that the operation state of the power network is abnormal.

[0035] It should be further explained that, in the specific implementation process, when it is determined that there is an abnormality in the operating status of the power network, a low-frequency voltage signal is injected into the power network. After the injection of the low-frequency voltage signal is completed, the monitoring center controls the three-phase integrated contactor to open the gate.

[0036] The operation detection data of the corresponding cable is obtained through the data acquisition terminal installed at the connection between the branch line and the busbar. The specific process includes:

[0037] The data acquisition terminal at the connection between the branch line and the busbar is marked as j=1, 2, ..., n, where n is an integer;

[0038] It should be further explained that, in the specific implementation process, after the low-frequency voltage signal is injected into the power network, a corresponding low-frequency current signal will be generated, and the low-frequency current signal will enter each branch line from the busbar;

[0039] The low-frequency input current of each branch line is obtained through the data acquisition terminal at the connection between each branch line and the busbar, and the low-frequency input current is marked as DD j ;

[0040] Obtaining the frequency of the low-frequency voltage signal injected into the power network, and marking the frequency of the low-frequency voltage signal injected into the power network as f;

[0041] The voltage value of the low-frequency voltage signal injected into the power grid is marked as U;

[0042] The data acquired by the data acquisition module is sent to the data processing module.

[0043] It should be further explained that, in the specific implementation process, the low-frequency input current generated by the injected low-frequency voltage signal is in the microampere level, and a terminal buffer is provided in each data acquisition terminal, which is used to cache the low-frequency input current generated by the low-frequency voltage signal.

[0044] The data processing module is used to process the data acquired by the data acquisition module. The specific processing process includes:

[0045] According to the voltage value U of the low-frequency voltage signal obtained by the data acquisition terminal at the connection between the branch line and the busbar and the frequency of the low-frequency voltage signal, the theoretical leakage current value LX of the cable corresponding to the data acquisition terminal is obtained. i , then LX i =k*c*U; where k is the leakage current constant of the cable, and c is the capacitance value in the data acquisition terminal;

[0046] Then obtain the actual leakage current value of the corresponding cable through the data acquisition terminal, and mark the actual leakage current value as SJ i ;

[0047] The processing structure of the data processing module is sent to the data analysis module.

[0048] The data analysis module is used to analyze the insulation status of the cable according to the processing result of the data processing module. The specific analysis process includes:

[0049] When SJ i ≤LX i When , it indicates that the insulation status of the corresponding cable is normal;

[0050] When SJ i >LX i When , it indicates that the insulation state of the corresponding cable is abnormal, and the position of the corresponding data acquisition terminal is marked, a fault detection instruction is generated, and the fault detection instruction is sent to the fault warning module.

[0051] The fault warning module is used to detect the cable with abnormal insulation state and generate corresponding warning information according to the detection result. The fault warning module detects the cable with abnormal insulation state specifically including:

[0052] After receiving the fault detection instruction, the data acquisition terminal installed at the connection between the branch line and the busbar generates a low-frequency pulse current, and marks the current value of the low-frequency pulse current as MI and the frequency of the low-frequency pulse current as MF;

[0053] Equidistant detection nodes are set on the corresponding cables, the cables are divided into several cable segments, and then low-frequency pulse current is injected into the corresponding cables;

[0054] Use a megohmmeter to test the cable in phases, that is, one of the three-phase current is used as the tested phase, and the other two phases are grounded, and the three-phase detection of the cable is carried out in turn;

[0055] Obtaining the leakage current value of the corresponding phase of each detection node, and obtaining the current difference between the leakage current value and the current value of the low-frequency pulse current;

[0056] A current difference change dot graph is generated according to the current difference of each node of the three-phase cable obtained. It should be further explained that, in the specific implementation process, each current difference obtained will be displayed in the current difference change dot graph in the form of a current difference point;

[0057] A warning interval is set in the current difference change dot graph, and the current difference points falling within the warning interval are marked;

[0058] According to the frequency of the low-frequency pulse current, the warning span time period is set; it should be further explained that, in the specific implementation process, the warning span time period is composed of two time vertical axes, the two time vertical axes respectively represent corresponding moments, and the corresponding moments represented are respectively the current moment and the initial moment with an interval length of t, and the time vertical axis represented by the initial moment is located before the time vertical axis represented by the current moment;

[0059] Mark the intersection area formed by the warning span time period and the warning interval, and obtain the number of current difference points in the intersection area, recorded as s;

[0060] When s≤1, the insulation resistance of the cable corresponding to the corresponding detection node is normal;

[0061] When s>1, the insulation resistance of the cable corresponding to the corresponding detection node is abnormal;

[0062] The cable segments with abnormal insulation resistance are marked, and warning information is generated and sent to the monitoring center.

[0063] It should be further explained that, in the specific implementation process, a multi-node phase detection is set up for the cable with abnormal insulation state through a low-frequency pulse current, so that when the cable has an abnormal insulation state, the location of the cable section that causes the abnormal insulation state can be further determined, thereby facilitating improving the efficiency of daily cable maintenance.

[0064] The above embodiments are only used to illustrate the technical method of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical method of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical method of the present invention.

Claims

1. Cable AI fault warning system, including a monitoring center, characterized in that: The monitoring center is communicatively connected to a data acquisition module, a data processing module, a data analysis module and a fault warning module; The cable includes a busbar and a branch line connected to the busbar, and the busbar is connected to a three-phase integrated contactor; The data acquisition module is composed of several data acquisition terminals, which are installed at the connection between the branch line and the busbar and on the three-phase integrated contactor. A data acquisition terminal is also installed at the end of the branch line to obtain circuit information of the cable during use. The zero-sequence voltage value of the busbar is obtained through the data acquisition terminal installed on the three-phase integrated contactor, and the zero-sequence voltage value is sent to the monitoring center, and the monitoring center determines the operating status of the power network according to the obtained zero-sequence voltage value; When it is determined that the operation status of the power network is abnormal, a low-frequency voltage signal is injected into the power network. After the injection of the low-frequency voltage signal is completed, the monitoring center controls the three-phase integrated contactor to open the gate; The operation detection data of the corresponding cable is obtained by a data acquisition terminal installed at the connection between the branch line and the busbar, and the obtained operation detection data is processed by a data processing module. The data analysis module is used to analyze the insulation state of the cable according to the processing result of the data processing module, and judge whether the insulation state of the cable is normal. If it is abnormal, a fault detection instruction is generated. The fault warning module detects the cable with abnormal insulation state according to the fault detection instruction, and determines the cable section causing the abnormal insulation state of the cable; The process of the fault warning module detecting the cable with abnormal insulation state includes: When receiving the fault detection command, the data acquisition terminal installed at the connection between the branch line and the busbar generates a low-frequency pulse current; Equidistant detection nodes are set on the corresponding cables, the cables are divided into several cable segments, and then low-frequency pulse current is injected into the corresponding cables; The cable is tested in phases by using a megohmmeter to obtain the leakage current value of the corresponding phase of each detection node, and the current difference between the leakage current value and the current value of the low-frequency pulse current; A current difference change dot graph is generated according to the current difference of each node of the three-phase cable, a warning interval is set in the current difference change dot graph, and a warning span time period is set according to the frequency of the low-frequency pulse current; the intersection area formed by the warning span time period and the warning interval is marked, and the number of current difference points in the intersection area is obtained, and whether the insulation resistance of the corresponding cable segment is normal is judged according to the number of current difference points in the obtained intersection area.

2. The cable AI fault warning system according to claim 1 is characterized in that: The data acquisition terminal obtains the zero-sequence voltage value of the busbar in a periodic manner, that is, the zero-sequence voltage value of the busbar is obtained once through the data acquisition terminal at every interval T time.

3. The cable AI fault warning system according to claim 2, characterized in that: The monitoring center's judgment process on the operating status of the power network includes: When the zero-sequence voltage value is greater than 0, the cycle of the data acquisition terminal acquiring the bus zero-sequence voltage value is adjusted, and the zero-sequence voltages of m groups of buses are continuously acquired; The zero-sequence voltage values ​​of m groups of buses are continuously acquired, the zero-sequence voltage values ​​of each group of buses are sequentially sorted according to the time sequence of acquisition, and it is determined whether there is an abnormality in the operation state of the power network.

4. The cable AI fault warning system according to claim 3 is characterized in that: The process of obtaining operation detection data includes: The low-frequency input current of each branch line is acquired through the data acquisition terminal at the connection between each branch line and the busbar, and the frequency and voltage value of the low-frequency voltage signal injected into the power network are obtained.

5. The cable AI fault early warning system according to claim 4, characterized in that: The low-frequency input current generated by the injected low-frequency voltage signal is in the microampere level. A terminal buffer is provided in each data acquisition terminal, and the terminal buffer is used to cache the low-frequency input current generated by the low-frequency voltage signal.

6. The cable AI fault early warning system according to claim 5, characterized in that: The processing process of the data processing module for the operation detection data includes: According to the voltage value of the low-frequency voltage signal and the frequency of the low-frequency voltage signal obtained by the data acquisition terminal at the connection between the branch line and the busbar, the theoretical leakage current value of the cable corresponding to the data acquisition terminal is obtained, and then the actual leakage current value of the corresponding cable is obtained through the data acquisition terminal.

7. The cable AI fault early warning system according to claim 6, characterized in that: The warning span time period is composed of two time vertical axes, which respectively represent corresponding moments, and the corresponding moments represented are the current moment and the initial moment with an interval of t. The time vertical axis represented by the initial moment is located before the time vertical axis represented by the current moment.

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