Insulation monitoring device and medium-voltage cable on-line monitoring system

Abstract

The utility model provides an insulation monitoring device, the insulation monitoring device is used for monitoring a medium voltage cable, the insulation monitoring device comprises a monitoring sensor which is integrally formed by pouring, the monitoring sensor comprises a low frequency sensing element, a high frequency sensing element and a pouring member, the low-frequency sensing elements and the high-frequency sensing elements are arranged in the pouring part at intervals. According to the insulation monitoring device provided by the invention, multiple and repeated installation of different sensors is avoided, the installation procedures are reduced, the installation is rapid, and when the insulation monitoring device is used for an online monitoring system, the equipment size and number are reduced, and the subsequent operation and maintenance management efficiency is improved; according to the monitoring sensing device, a low-frequency sensing element and a high-frequency sensing element are integrally designed, and when the monitoring sensing device is used for an online monitoring system, data comprehensive diagnosis can be achieved, meanwhile, the use amount of communication cables is reduced, cost is reduced, and relevance between the low-frequency sensing element and the high-frequency sensing element is enhanced; and comprehensive analysis and diagnosis of the monitored object according to the monitoring data are realized.

Description

Technical Field

[0001] This utility model relates to the field of online monitoring technology for medium-voltage cables, and in particular to an insulation monitoring device and an online monitoring system for medium-voltage cables. Background Technology

[0002] Power cables are cables used to transmit and distribute electrical energy. The safe and stable operation of power cables is crucial for the reliable power supply of urban power grids. Traditional offline testing methods suffer from drawbacks such as complex operation, high labor costs, and low coverage. In contrast, online cable insulation monitoring technology enables real-time online monitoring and condition assessment of cables.

[0003] Currently, various methods have been developed for online monitoring of cable insulation, such as partial discharge monitoring, temperature monitoring, and grounding current monitoring. Cable leakage current is the current generated between the insulation layer and the sheath. The magnitude of the leakage current is closely related to the performance of the cable insulation layer. By detecting the leakage current and analyzing its changing characteristics, the condition of the cable insulation layer can be assessed, allowing for timely detection of insulation damage and aging. Statistical data shows that over 90% of cable faults are caused by joint failures. By performing partial discharge monitoring at cable terminations and intermediate joints, problems can be detected promptly, preventing accidents from occurring.

[0004] Online monitoring devices and systems for partial discharge monitoring and leakage current detection at cable terminations and intermediate joints have the following problems: 1) Currently used online monitoring devices are based on different principles and methods, requiring different sensors, monitoring hosts, and analysis software. This results in a large number of sensors and devices, cumbersome configuration, repetitive installation, large overall size of the monitoring equipment, and low efficiency in subsequent operation and maintenance management; 2) The diagnostic methods are singular, using different sensors and monitoring hosts. The correlation between different monitoring devices (such as high-frequency partial discharge monitoring devices and leakage current detection devices) is weak, and there is a lack of cross-application of data and joint diagnosis between monitoring methods, which cannot effectively achieve comprehensive diagnosis of the monitored object based on monitoring data. Utility Model Content

[0005] This utility model addresses the problems of existing online monitoring devices for partial discharge monitoring and leakage current detection, which use different sensors and monitoring equipment, resulting in cumbersome device installation, low operation and maintenance efficiency, weak correlation between different monitoring devices, and inability to achieve comprehensive diagnosis of the monitored object based on monitoring data. This application provides an insulation monitoring device and an online monitoring system for medium-voltage cables.

[0006] In a first aspect, this application provides an insulation monitoring device for monitoring medium-voltage cables. The insulation monitoring device includes an integrally cast monitoring sensor, which includes a low-frequency sensing element, a high-frequency sensing element, and a cast element. The low-frequency sensing element and the high-frequency sensing element are both spaced apart within the cast element.

[0007] Preferably, the low-frequency sensing element and the high-frequency sensing element are spaced apart along the axial direction of the casting.

[0008] Preferably, the distance d1 between the low-frequency sensing element and the high-frequency sensing element is greater than 0.

[0009] Preferably, both the low-frequency sensing element and the high-frequency sensing element are ring coils, and the casting is a ring-shaped insulating component.

[0010] Preferably, the monitoring sensor includes a casting housing, the casting component is disposed inside the casting housing, and the casting housing is fixedly connected to the casting component;

[0011] The cast outer shell includes a first outer shell and a second outer shell, which are connected by bolts.

[0012] Preferably, the casting shell is an annular component, and the inner diameter d2 of the casting shell is ≥62mm.

[0013] Preferably, a first protrusion is provided on each side of the first housing, and a second protrusion is provided on each side of the second housing. The first protrusion is provided with a first connecting hole, and the second protrusion is provided with a second connecting hole. The first protrusion is connected to the second protrusion by the bolt passing through the first connecting hole and the second connecting hole.

[0014] Preferably, the insulation monitoring device further includes a mounting base, the monitoring sensor is disposed on the mounting base, the mounting base is provided with a first electrical connection socket and a second electrical connection socket, the first electrical connection socket is electrically connected to the high-frequency sensing element, and the second electrical connection socket is electrically connected to the low-frequency sensing element.

[0015] Secondly, this application provides an online monitoring system for medium-voltage cables, including the insulation monitoring device described above.

[0016] The insulation monitoring device provided in this application features an integrally cast monitoring sensor that integrates low-frequency sensing elements, high-frequency sensing elements, and the cast component into a single unit. This facilitates the transport of the monitoring sensor and allows for high-frequency partial discharge and leakage current monitoring of medium-voltage cables at the required locations using a single sensor. This eliminates the need for separate low-frequency and high-frequency sensors, avoiding multiple and repetitive installations, reducing installation steps, and speeding up installation. When used in online monitoring systems, it reduces equipment size and quantity, improving subsequent operation and maintenance efficiency. The integrated design of the low-frequency and high-frequency sensing elements in the monitoring sensor allows for comprehensive data diagnosis in online monitoring systems while reducing the amount of communication cables used, lowering costs, and enhancing the correlation between the low-frequency and high-frequency sensing elements. This enables comprehensive analysis and diagnosis of the monitored object based on monitoring data. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of an insulation monitoring device provided in one embodiment of the present invention;

[0018] Figure 2 It is along Figure 1 Top view of the structure after being cut in the direction of the middle arrow;

[0019] Figure 3 This is a top view of an insulation monitoring device provided in an embodiment of this utility model;

[0020] Figure 4 This is a front view of an insulation monitoring device provided in an embodiment of this utility model;

[0021] Figure 5 This is a bottom view of an insulation monitoring device provided in an embodiment of this utility model;

[0022] Figure 6 This is a left view of an insulation monitoring device provided in an embodiment of this utility model;

[0023] Figure 7 This is a schematic diagram of the test structure of an insulation monitoring device provided in one embodiment of the present invention.

[0024] 1. Low-frequency sensing element; 2. High-frequency sensing element; 3. Casting component; 4. Casting housing; 401. First housing; 402. Second housing; 5. Mounting base; 501. Support base; 502. Base; 601. First protrusion; 602. Second protrusion; 701. First electrical connection socket; 702. Second electrical connection socket; 8. Monitoring object. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the present utility model.

[0026] To illustrate the technical solution of this utility model, specific embodiments are described below.

[0027] like Figures 1-6 As shown, an embodiment of the present invention provides an insulation monitoring device for monitoring medium-voltage cables. The insulation monitoring device includes an integrally cast monitoring sensor. The monitoring sensor includes a low-frequency sensing element 1, a high-frequency sensing element 2, and a cast-in-place component 3. The low-frequency sensing element 1 and the high-frequency sensing element 2 are both spaced apart within the cast-in-place component 3.

[0028] Specifically, the insulation monitoring device of this application is mainly used to monitor the high-frequency partial discharge and leakage current of medium-voltage cables, wherein the voltage range of the medium-voltage cables is 10kV~30kV.

[0029] A one-piece cast monitoring sensor refers to a sensor where, during manufacturing, the low-frequency sensing element 1 and the high-frequency sensing element 2 are directly placed into a mold and cast, thus forming a single unit consisting of the low-frequency sensing element 1, the high-frequency sensing element 2, and the cast component 3. For example... Figure 2 As shown, the monitoring sensor is integrally cast. A low-frequency sensing element 1 and a high-frequency sensing element 2 are installed within the casting 3, spaced apart. The high-frequency sensing element 2 is used to monitor whether the medium-voltage cable has high-frequency partial discharge, while the low-frequency sensing element 1 is used to monitor whether the medium-voltage cable has leakage current. The casting 3, low-frequency sensing element 1, and high-frequency sensing element 2 form a single unit. When monitoring high-frequency partial discharge and leakage current of the medium-voltage cable, it is unnecessary to install separate low-frequency and high-frequency sensors, reducing installation steps, speeding up installation, and also reducing the space occupied by the low-frequency and high-frequency sensors.

[0030] The material of the casting component 3 can be rubber or other materials. This application does not limit the material as long as it does not affect the monitoring of the medium voltage cable by the low frequency sensing element 1 and the high frequency sensing element 2.

[0031] This application provides an insulation monitoring device with an integrally cast monitoring sensor. The low-frequency sensing element 1, high-frequency sensing element 2, and the cast component 3 are integrated into a single unit. This facilitates the transport of the monitoring sensor. In use, a single sensor can monitor high-frequency partial discharge and leakage current at the required locations on medium-voltage cables, eliminating the need for separate low-frequency and high-frequency sensors. This avoids multiple and repetitive installations of different sensors, reducing installation steps and speeding up the process. When used in online monitoring systems, it reduces the size and number of devices, improving subsequent operation and maintenance efficiency. The integrated design of the low-frequency sensing element 1 and high-frequency sensing element 2, when used in online monitoring systems, enables comprehensive data diagnosis while reducing the amount of communication cables used, lowering costs, and enhancing the correlation between the low-frequency sensing element 1 and high-frequency sensing element 2. This allows for comprehensive analysis and diagnosis of the monitored object 8 based on monitoring data.

[0032] In some embodiments, the low-frequency sensing element 1 and the high-frequency sensing element 2 are spaced apart along the axial direction of the casting 3.

[0033] Specifically, such as Figure 1 , 2 As shown, both the high-frequency sensing element 2 and the low-frequency sensing element 1 are set inside the casting 3, and are spaced apart along the axial direction of the casting 3. This makes it easy to monitor high-frequency partial discharge signals or leakage current signals based on different frequency band signals, and there is no interference between the high-frequency sensing element 2 and the low-frequency sensing element 1.

[0034] When high-frequency partial discharge occurs in a medium-voltage cable, it is generated at a relatively high frequency, generally around 3MHz. This signal will be transmitted along the outer insulation armor layer of the medium-voltage cable. During cable installation, the cable armor layer needs to be grounded with a copper wire to prevent the induced voltage on the armor layer from causing harm to the human body. Therefore, the copper wire is passed through the high-frequency sensing element 2 (loop coil). If a signal in this frequency band is generated, the high-frequency sensing element 2 can collect the high-frequency signal and determine that partial discharge has occurred on the medium-voltage cable.

[0035] Under normal circumstances, the leakage current is within a relatively stable and small range. If the leakage current exceeds the specified value, it often indicates a problem with the insulation, such as insulation aging or damage. By collecting the changing leakage current through the low-frequency sensing element 1, early abnormalities in the insulation can be detected in a timely manner, allowing for equipment inspection and maintenance. This prevents safety accidents such as leakage and short circuits caused by insulation failure, ensuring the safety of equipment and personnel.

[0036] In some embodiments, the distance d1 between the low-frequency sensing element 1 and the high-frequency sensing element 2 is greater than 0.

[0037] Specifically, such as Figure 2 As shown, within the casting component 3, the distance d1 between the low-frequency sensing element 1 and the high-frequency sensing element 2 is greater than 0, which avoids signal acquisition interference between the low-frequency sensing element 1 and the high-frequency sensing element 2 and improves the accuracy of data acquisition.

[0038] In some embodiments, the low-frequency sensing element 1 and the high-frequency sensing element 2 are both loop coils, and the casting part 3 is a loop insulating part.

[0039] Specifically, both the low-frequency sensing element 1 and the high-frequency sensing element 2 are ring coils, and the corresponding casting part 3 is also a ring structure. At the same time, the casting part 3 is made of insulating material to ensure the accuracy of monitoring of medium-voltage cables by the low-frequency sensing element 1 and the high-frequency sensing element 2.

[0040] In some embodiments, the monitoring sensor includes a casting housing 4, the casting component 3 is disposed inside the casting housing 4, and the casting housing 4 is fixedly connected to the casting component 3;

[0041] The cast outer shell 4 includes a first outer shell 401 and a second outer shell 402, which are connected by bolts.

[0042] Specifically, the outer shell 4 and the casting component 3 are fixedly connected, such as... Figure 1 As shown, both the first outer shell 401 and the second outer shell 402 are provided with multiple threaded holes. Screws are directly screwed into the threaded holes, thereby fixing the first outer shell 401 and the second outer shell 402 to the casting component 3.

[0043] The material of the cast outer shell 4 is an insulating material, such as rubber.

[0044] like Figure 1 As shown, the cast outer shell 4 includes a first outer shell 401 and a second outer shell 402. The first outer shell 401 and the second outer shell 402 are fixedly connected by bolts, which also serves to protect the low-frequency sensing element 1 and the high-frequency sensing element 2.

[0045] In some embodiments, the cast outer shell 4 is an annular component, and the inner diameter d2 of the cast outer shell 4 is ≥62mm.

[0046] like Figure 1 , 4 As shown, Figure 4 This is a front view of the insulation monitoring device of this application. Both the high-frequency sensing element 2 and the low-frequency sensing element 1 are ring coils, and the corresponding casting part 3 also has a ring structure. The casting shell 4 is disposed outside the casting part 3 and is also a ring structure. When using the insulation monitoring device to monitor the monitored part of a medium-voltage cable, the monitored part is inserted into... Figure 4 In the inner ring of the middle section shown.

[0047] The inner diameter d2 of the cast outer shell 4 is ≥ 62mm, which is... Figure 4 The diameter of the inner ring in the middle is limited to d2 greater than or equal to 62mm to facilitate insertion of the monitored area. Figure 4 , Figure 7 In the inner ring shown in the middle, the high-frequency partial discharge and leakage current of the monitoring object 8 are monitored.

[0048] In some embodiments, a first protrusion 601 is provided on each side of the first housing 401, and a second protrusion 602 is provided on each side of the second housing 402. A first connecting hole is provided on the first protrusion 601, and a second connecting hole is provided on the second protrusion 602. The first protrusion 601 is connected to the second protrusion 602 by means of a bolt passing through the first connecting hole and the second connecting hole.

[0049] Specifically, such as Figure 1 , 4 As shown, the cross-sectional views of the first protrusion 601 and the second protrusion 602 can be polygonal, circular, or elliptical, etc. The first protrusion 601 and the second protrusion 602 are arranged side-by-side in a direction parallel to the axial direction of the casting shell 4. The shapes of the first protrusion 601 and the second protrusion 602 can be the same or different. The first protrusion 601 is provided with a first connecting hole, and the second protrusion 602 is provided with a second connecting hole. A bolt passes through the first connecting hole and the second connecting hole in sequence. A nut is located on the side of the second protrusion 602 opposite to the first protrusion 601, and the nut is threadedly connected to the bolt, thereby fixing the first protrusion 601 and the second protrusion 602 together.

[0050] In some embodiments, the insulation monitoring device further includes a mounting base 5, the monitoring sensor is disposed on the mounting base 5, the mounting base 5 is provided with a first electrical connection socket 701 and a second electrical connection socket 702, the first electrical connection socket 701 is electrically connected to the high-frequency sensing element 2, and the second electrical connection socket 702 is electrically connected to the low-frequency sensing element 1.

[0051] Specifically, such as Figure 1As shown, the mounting base 5 includes a support base 501 and a base 502. The support base 501 is mounted on the base 502, and the monitoring sensor is mounted on the side of the support base 501 away from the base 502. The support base 501 is provided with a first electrical connection socket 701 and a second electrical connection socket 702. The first electrical connection socket 701 is electrically connected to the high-frequency sensing element 2. The data monitored by the high-frequency sensing element 2 can be transmitted to the data acquisition unit through the communication cable connected to the first electrical connection socket 701. The second electrical connection socket 702 is electrically connected to the low-frequency sensing element 1. The data monitored by the low-frequency sensing element 1 can be transmitted to the data acquisition unit through the communication cable connected to the second electrical connection socket 702. This enables the simultaneous transmission of data monitored by the monitoring sensors within the same time period to the data acquisition unit. The data acquisition unit then transmits the data to the monitoring and diagnostic software, which performs comprehensive analysis and diagnosis based on the monitoring data within the same time period.

[0052] Secondly, this application provides an online monitoring system for medium-voltage cables, including the insulation monitoring device described above.

[0053] Compared to existing online monitoring systems that contain separate high-frequency and low-frequency sensors, the medium-voltage cable online monitoring system provided in this application, including the aforementioned insulation monitoring device, features an integrated design that reduces the number of sensors, avoids repeated installation of different sensors, reduces the overall size of the online monitoring system, and improves the efficiency of subsequent operation and maintenance. The integrated design of the insulation monitoring device allows the online monitoring system to perform comprehensive data diagnosis based on data collected by the device within the same time period, enabling comprehensive data analysis and diagnosis. Furthermore, the integrated design of the insulation monitoring device reduces the amount of communication cables used, lowering costs.

[0054] In some embodiments, the medium-voltage cable online monitoring system further includes a data acquisition unit, a data transmission unit, and monitoring and diagnostic software. The insulation monitoring device is electrically connected to the data acquisition unit, the data acquisition unit is electrically connected to the data transmission unit, and the data transmission unit is electrically connected to the monitoring and diagnostic software.

[0055] When the insulation monitoring device provided in this application is used in a medium-voltage cable online monitoring system, the insulation monitoring device contains both a low-frequency sensing element 1 and a high-frequency sensing element 2. The low-frequency sensing element 1 tests the leakage current of the medium-voltage cable and transmits the data to the data acquisition unit of the monitoring system. The high-frequency sensing element 2 tests the high-frequency partial discharge signal of the medium-voltage cable and transmits the data to the data acquisition unit of the monitoring system. The monitored data can be transmitted to the data acquisition unit simultaneously within the same time period, achieving signal synchronization. The correlation between the low-frequency sensing element 1 and the high-frequency sensing element 2 is strong. The data acquisition unit transmits the collected data to the data transmission unit, which then transmits the data to the monitoring and diagnostic software. The monitoring and diagnostic software can perform comprehensive analysis and judgment based on the monitoring data collected within the same time period. The monitoring data can be cross-application for joint diagnosis, enabling effective and accurate comprehensive diagnosis of the monitored object 8 based on the monitoring data from the same period.

[0056] The aforementioned data acquisition unit, data transmission unit, and monitoring and diagnostic software are all existing technologies.

[0057] The above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model, and should all be included within the protection scope of this utility model.

Claims

1. An insulation monitoring device, characterized in that The insulation monitoring device is used to monitor medium-voltage cables. The insulation monitoring device includes an integrally cast monitoring sensor. The monitoring sensor includes a low-frequency sensing element, a high-frequency sensing element, and a cast element. The low-frequency sensing element and the high-frequency sensing element are both spaced apart in the cast element.

2. The insulation monitoring arrangement according to claim 1, characterized in that The low-frequency sensing element and the high-frequency sensing element are spaced apart along the axial direction of the casting.

3. The insulation monitoring arrangement according to claim 1, characterized in that The distance d1 between the low-frequency sensing element and the high-frequency sensing element is greater than 0.

4. The insulation monitoring arrangement according to claim 1, characterized in that Both the low-frequency sensing element and the high-frequency sensing element are ring coils, and the casting is a ring-shaped insulating component.

5. The insulation monitoring arrangement according to claim 4, characterized in that The monitoring sensor includes a casting housing, the casting component is disposed inside the casting housing, and the casting housing is fixedly connected to the casting component; The cast outer shell includes a first outer shell and a second outer shell, which are connected by bolts.

6. The insulation monitoring arrangement according to claim 5, characterized in that The casting shell is a ring-shaped part, and the inner diameter d2 of the casting shell is ≥62mm.

7. The insulation monitoring arrangement according to claim 5, characterized in that The first housing has a first protrusion on each side, and the second housing has a second protrusion on each side. The first protrusion has a first connecting hole, and the second protrusion has a second connecting hole. The first protrusion is connected to the second protrusion by the bolt passing through the first connecting hole and the second connecting hole.

8. The insulation monitoring arrangement according to claim 1, characterized in that The insulation monitoring device further includes a mounting base, on which the monitoring sensor is mounted. The mounting base is provided with a first electrical connection port and a second electrical connection port. The first electrical connection port is electrically connected to the high-frequency sensing element, and the second electrical connection port is electrically connected to the low-frequency sensing element.

9. A medium voltage cable on-line monitoring system, characterized by Includes the insulation monitoring device as described in any one of claims 1-8.

Images