CN117849549A - Cable discharge signal measuring device and switch cabinet - Google Patents

Abstract

The application relates to the technical field of power equipment, in particular to a cable discharge signal measuring device and a switch cabinet, comprising: the sleeve body is provided with an insulating interlayer; the conductive piece is arranged in the insulating interlayer; the capacitive coupling unit is connected with the conductive piece through a cable; and the amplifier is connected with the capacitive coupling unit and is used for amplifying and outputting the discharge signal. According to the cable partial discharge detection device, the conductive piece is arranged in the insulating interlayer, so that partial discharge signals of the cable can be sensitively detected; the capacitive coupling unit and the amplifier are externally connected on the conductive piece, so that signals are transmitted to the capacitive coupling unit and the amplifier, external interference signals can be restrained, discharge signals are amplified, and better detection effect is achieved; through setting up the electrically conductive piece in the sleeve pipe body, realize the integration preparation and the application of sleeve pipe and electrically conductive piece, can reduce cable discharge signal measuring device's occupation space when improving detection sensitivity.

Description

Cable discharge signal measuring device and switch cabinet

Technical Field

The present application relates to the technical field of electric power equipment, and in particular to a cable discharge signal measuring device and a switch cabinet.

Background technique

The switch cabinet is an electrical equipment. The external line of the switch cabinet first enters the main control switch in the cabinet, and then enters the sub-control switch. Each branch is set according to its needs. Such as instruments, automatic control, motor magnetic switches, various AC contactors, etc. Some also have high-voltage and low-voltage room switch cabinets, with high-voltage busbars, such as power plants, etc. Some are also equipped with low-frequency load shedding to protect the main equipment. The main function of the switch cabinet is to open, control and protect electrical equipment during the power generation, transmission, distribution and energy conversion of the power system. The components in the switch cabinet mainly include circuit breakers, disconnectors, load switches, operating mechanisms, mutual inductors and various protective devices. There are many ways to classify switch cabinets. For example, according to the installation method of the circuit breaker, it can be divided into removable switch cabinets and fixed switch cabinets; or according to the different cabinet structures, it can be divided into open switch cabinets, metal-enclosed switch cabinets, and metal-enclosed armored switch cabinets; according to different voltage levels, it can be divided into high-voltage switch cabinets, medium-voltage switch cabinets and low-voltage switch cabinets. It is mainly applicable to various occasions such as power plants, substations, petrochemicals, metallurgy and steel rolling, light industry and textiles, factories and mines, residential areas, high-rise buildings, etc. Partial discharge is a discharge that occurs only in a part of the insulator. These discharges may also occur on electrodes, but they may also occur in the electric field space "without electrodes". Partial discharges can occur in: gases, liquids and solids. When partial discharge occurs, not only will losses occur, but the high-energy electrons and UV radiation generated will damage the surrounding insulating materials.

Abnormal discharge in high-voltage switchgear or ring network cabinet is an important factor endangering the insulation safety of the cabinet and cable. Effective detection of abnormal discharge of the switchgear connecting cable head and cable body is an important means of status assessment and fault warning of switchgear and cable equipment. At present, ultra-high frequency detection method, high-frequency current detection method, ultrasonic detection method and optical measurement method are the more mainstream online monitoring methods. The above methods all realize discharge signal measurement through front-end electromagnetic, current and acoustic signal coupling. However, in the measurement of partial discharge of cables, the above methods all have practical problems such as difficulty in identifying interference sources, difficulty in separating signals from noise, and detection sensitivity being affected by environmental interference, resulting in the discharge signal often being buried in the external noise of the equipment.

Summary of the invention

Based on this, it is necessary to provide a cable discharge signal measuring device and a switch cabinet to address the problem that the discharge signal is buried in the external noise of the equipment.

According to one aspect of the present application, a cable discharge signal measuring device is provided, comprising:

The bushing body has an insulating interlayer;

A conductive member, disposed in the insulating interlayer;

A capacitive coupling unit is connected to the conductive member via a coaxial cable;

An amplifier is connected to the capacitive coupling unit, and is used to amplify and output the discharge signal.

In one embodiment, the conductive member is a conductive polymer film, and the conductive member includes a base layer, an adhesive layer and an electrode layer, the adhesive layer is arranged between the base layer and the electrode layer, and the electrode layer is embedded with an electrode lead.

In one embodiment, the conductive member is in a strip shape and is wound in the insulating interlayer.

In one of the embodiments, a signal line slot is opened on the sleeve body, and the conductive member passes through the signal line slot and is connected to the capacitive coupling unit.

In one of the embodiments, a fixing sleeve is provided in the signal line slot, and the fixing sleeve is used to fix the conductive member, and the conductive member is inserted into the fixing sleeve.

In one of the embodiments, a limiting member is provided on the inner wall of the fixing sleeve, and the limiting member can limit the conductive member.

In one of the embodiments, the capacitive coupling unit is a capacitive or resistive-capacitive circuit element, and the capacitive coupling unit is connected in parallel with the inner core of the coaxial cable.

In one embodiment, the amplifier is a transimpedance amplifier, and the transimpedance amplifier is composed of one or more stages of amplification circuits.

According to another aspect of the present application, a switch cabinet is provided, comprising a cabinet body and the above-mentioned cable discharge signal measuring device, wherein the cable discharge signal measuring device is installed in the cabinet body.

In one embodiment, the switch cabinet has a busbar room, a circuit breaker trolley room, a cable room and a relay instrument room. The busbar is arranged in the busbar room, the bushing body is installed in the busbar, a connecting plate is installed on the bushing body, and the bushing body is fixed in the busbar room through the connecting plate.

The above-mentioned cable discharge signal measuring device and switch cabinet can sensitively detect the partial discharge signal of the cable by arranging the conductive part in the insulating interlayer; by externally connecting a capacitive coupling unit and an amplifier to the conductive part and transmitting the signal to the capacitive coupling unit and the amplifier, it is possible to suppress external interference signals and amplify the discharge signal, which helps to achieve better detection effects; by arranging the conductive part in the bushing body, the integrated production and application of the bushing and the conductive part are realized, which can improve the detection sensitivity while reducing the occupied space of the cable discharge signal measuring device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of the overall structure of a switch cabinet in an embodiment of the present application.

FIG. 2 is a schematic diagram of the structure of a cable discharge signal measuring device in an embodiment of the present application.

FIG3 is a cross-sectional view of the fixing sleeve and the discharge member in the embodiment of the present application.

FIG. 4 is a graph of a voltage signal and a discharge signal measured in an embodiment of the present application.

Description of reference numerals:

10. Switch cabinet; 100. Cabinet; 110. Busbar room; 120. Circuit breaker trolley room; 130. Cable room; 140. Relay instrument room; 20. Cable discharge signal measuring device; 210. Bushing body; 220. Connecting plate; 230. Insulating interlayer; 240. Conductive part; 250. Capacitive coupling unit; 260. Amplifier; 270. Signal line duct; 30. Fixing sleeve; 310. Limiting part.

Detailed ways

In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

In the description of the present application, it should be understood that if the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. appear, the orientation or position relationship indicated by these terms is based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

In addition, if the terms "first" or "second" appear, these terms are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, if the term "plurality" appears, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

In this application, unless otherwise clearly specified and limited, if the terms "installed", "connected", "connected", "fixed" and the like appear, these terms should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integrated connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

In the present application, unless otherwise clearly specified and limited, if there is a description that a first feature is "on" or "below" a second feature, etc., or similar descriptions appear, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "above" and "above" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being "below", "below" and "below" the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

It should be noted that if an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. If an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. If any, the terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used in this application are for illustrative purposes only and do not represent the only implementation method.

The switch cabinet is an electrical equipment. The external line of the switch cabinet first enters the main control switch in the cabinet, and then enters the sub-control switch. Each branch is set according to its needs. Such as instruments, automatic control, motor magnetic switches, various AC contactors, etc. Some also have high-voltage and low-voltage room switch cabinets, with high-voltage busbars, such as power plants, etc. Some are also equipped with low-frequency load shedding to protect the main equipment. The main function of the switch cabinet is to open, control and protect electrical equipment during the power generation, transmission, distribution and energy conversion of the power system. The components in the switch cabinet mainly include circuit breakers, disconnectors, load switches, operating mechanisms, mutual inductors and various protective devices. There are many ways to classify switch cabinets. For example, according to the installation method of the circuit breaker, it can be divided into removable switch cabinets and fixed switch cabinets; or according to the different cabinet structures, it can be divided into open switch cabinets, metal-enclosed switch cabinets, and metal-enclosed armored switch cabinets; according to different voltage levels, it can be divided into high-voltage switch cabinets, medium-voltage switch cabinets and low-voltage switch cabinets. It is mainly applicable to various occasions such as power plants, substations, petrochemicals, metallurgy and steel rolling, light industry and textiles, factories and mines, residential areas, high-rise buildings, etc. Partial discharge is a discharge that occurs only in a part of the insulator. These discharges may also occur on electrodes, but they may also occur in the electric field space "without electrodes". Partial discharges can occur in: gases, liquids and solids. When partial discharge occurs, not only will losses occur, but the high-energy electrons and UV radiation generated will damage the surrounding insulating materials.

Referring to FIG. 1 , FIG. 1 shows a schematic diagram of the structure of a switch cabinet 10 in an embodiment of the present application. The switch cabinet 10 provided in an embodiment of the present application includes a cabinet 100, wherein the cabinet 100 has a busbar chamber 110, a circuit breaker trolley chamber 120, a cable chamber 130 and a relay instrument chamber 140. A circuit breaker is installed in the circuit breaker trolley chamber 120, a cable and a lightning arrester are arranged in the cable chamber 130, and a busbar is installed in the busbar chamber 110. During the installation and use of the switch cabinet 10, partial discharge is easily caused by various problems. Abnormal discharge in the switch cabinet 10 is an important factor endangering the insulation safety of the cabinet and the cable. Partial discharge is a discharge that occurs only in a part of the insulator. These discharges may also occur on electrodes, but they may also occur in the electric field space "without electrodes". Partial discharge can occur in: gas, liquid and solid. When partial discharge occurs, not only will loss occur, but the high-energy electrons and UV radiation generated by it will damage the surrounding insulating materials. In the case where partial discharge causes slight to severe damage to the insulator, its measurement becomes particularly important, so it is necessary to effectively detect whether the switch cabinet 10 has partial discharge phenomenon.

At present, ultra-high frequency detection method, high frequency current detection method, ultrasonic detection method and optical detection method are the more mainstream online monitoring methods. All of the above methods realize discharge signal measurement through coupling of front-end electromagnetic, current and acoustic signals. However, in the measurement of partial discharge of cables, the above methods all have practical problems such as difficulty in identifying interference sources, difficulty in separating signals from noise, and detection sensitivity being affected by environmental interference, which results in the discharge signal often being buried in the external noise of the equipment.

To this end, the present application provides a cable discharge signal measuring device for detecting the discharge signal of the cable, which can suppress interference signals. The structure of the cable discharge signal measuring device is described below. It can be understood that in other embodiments, the cable discharge signal measuring device is not limited to being installed in a switch cabinet, but can also be installed on cables of other equipment to detect the discharge signal, which is not limited here.

Referring to Fig. 1 and Fig. 2, Fig. 2 shows a schematic diagram of the structure of a cable discharge signal measuring device 20, which includes a bushing body 210, which is sleeved outside the bus cable, and a connecting plate 220 is fixed to the bushing body 210, and the bushing body 210 is fixed in the bus chamber 110 through the connecting plate 220. The bushing body 210 and the connecting plate 220 are used to support and fix the bus.

1 and 2 , an insulating interlayer 230 is disposed in the bushing body 210 , and a conductive member 240 is disposed in the insulating interlayer 230 . The conductive member 240 is in a rectangular strip shape and is wound in the insulating interlayer 230 of the bushing body 210 . The conductive member 240 is bonded to the insulating interlayer 230 by cold pressing.

Referring to Fig. 1 and Fig. 2, the conductive member 240 is connected with a coaxial cable connector with a self-matched head end, the conductive member 240 is externally connected to the coaxial cable through the coaxial cable connector, and is connected with a capacitive coupling unit 250 through the coaxial cable, and the capacitive coupling unit 250 is a capacitive or resistive-capacitive circuit element, and the capacitance value ranges from 150pF to 500pF. The capacitive coupling unit 250 is arranged outside the insulating interlayer 230, and the capacitive coupling unit 250 is connected in parallel with the inner core of the coaxial cable. The capacitive coupling unit 250 achieves the purpose of filtering by transmitting the signal to a capacitor and then obtaining the signal from the capacitor. Filtering is the operation of filtering out a specific band frequency in a signal, and is an important measure to suppress and prevent interference. By setting the capacitive coupling unit 250, the ambient noise band frequency in the discharge signal can be filtered out to achieve signal-to-noise separation.

Referring to FIG. 1 and FIG. 2, the capacitive coupling unit 250 is externally connected to an amplifier 260, and the amplifier 260 is used to amplify and output the electrical signal passing through the capacitive coupling unit 250. The amplifier 260 is a transimpedance amplifier 260, which is composed of a transimpedance one-stage or multi-stage amplifier circuit. The main working principle of the transimpedance amplifier is to convert the input voltage signal into a current signal. When the input voltage signal is applied to the resistor, the resistor generates a current, which is amplified by the operational amplifier. In the transimpedance amplifier 260, the negative feedback loop of the operational amplifier is established by a resistor, so when the input voltage signal changes, the current on the resistor will also change accordingly, so that the output current is adjusted. In this process, the gain of the transimpedance amplifier 260 depends on the value of the resistor and the amplification factor of the operational amplifier. Since there is a linear relationship between its output current and the input voltage, the transimpedance amplifier 260 can provide higher sensitivity and dynamic range. Secondly, the transimpedance amplifier can be used for a wide range of signal processing. In addition, since the transimpedance amplifier only requires an operational amplifier and a resistor as components, the cost is relatively low and it is easy to manufacture and integrate.

Referring to Figures 1 and 2, by setting the conductive member 240 in the insulating interlayer 230, the local discharge signal of the cable can be sensitively detected; by externally connecting the capacitive coupling unit 250 and the amplifier 260 to the conductive member 240 and transmitting the signal to the capacitive coupling unit 250 and the amplifier 260, the external interference signal can be suppressed and the discharge signal can be amplified, which helps to achieve a better detection effect; by setting the conductive member 240 in the bushing body 210, the integrated production and application of the bushing and the conductive member 240 are realized, which can improve the detection sensitivity while reducing the occupied space of the cable discharge signal measuring device 20.

Specifically, in the present embodiment, the conductive member 240 is specifically a conductive polymer film, and the conductive polymer film is composed of a high polymer conductive electrode with a thickness not exceeding 0.5 mm. The conductive polymer film is based on the characteristics of conductive materials. The conductive material has the characteristics of free movement of electrons. They can transfer charges inside the material and convert electrical energy into other forms of energy output. The conductive member 240 includes a base layer, an adhesive layer and an electrode layer. The adhesive layer is arranged on the base layer, and the adhesive layer is arranged between the base layer and the electrode layer to connect the base layer and the electrode layer. An electrode lead is embedded in the electrode layer. When an external electric field acts on the electrode layer, electrons move freely in the conductive electrode layer and output current on the electrode. The electrode lead can lead the discharge signal of the cable to the capacitive coupling unit 250.

Conductive polymer film has good conductivity and flexibility, can be bent and stretched as needed, and has low resistivity, which can be used in low-energy electronic devices. Compared with traditional metal electrodes, conductive polymer film has the advantages of light weight, good flexibility and high plasticity. By wrapping the conductive polymer film in the insulating interlayer, the partial discharge of the cable can be better transmitted and detected, which helps to ensure the detection efficiency and detection effect.

Referring to FIG. 2 and FIG. 3 , a signal line groove 270 is provided on the sleeve body 210, and the signal line groove 270 is used to lead the conductive member 240 out of the insulating interlayer 230. A fixing sleeve 30 is provided in the signal line groove 270. The fixing sleeve 30 is composed of a flat wire cast by epoxy, and the fixing sleeve 30 is tightly attached to the inner wall of the sleeve body 210 by epoxy casting. The length of the signal line groove 270 is 0.5-1 cm, and preferably 0.8 cm in this embodiment.

Referring to Figures 2 and 3, a limiting member 310 is provided in the fixing sleeve 30. The limiting member 310 is integrally formed with the fixing sleeve 30. The limiting member 310 may be a limiting block or a limiting ring. In the present embodiment, it is preferably a limiting ring. The limiting member 310 is provided in the middle of the fixing sleeve 30. The limiting member 310 is used to limit the conductive member 240 to prevent the conductive member 240 from shaking in the fixing sleeve 30 as much as possible, thereby ensuring the stability of the conductive member 240.

In summary, referring to Figure 4, the horizontal axis in Figure 4 is time and the vertical axis is voltage. Figure 4 shows a curve diagram of the discharge signal obtained by coupling the cable discharge signal measuring device. It can be seen that the present application can accurately identify the real discharge signal components with the same frequency and phase as the power frequency cycle under complex electromagnetic, acoustic, and optical non-periodic interference conditions, avoiding non-periodic interference while improving the signal-to-noise ratio of the discharge detection signal processing.

In addition, the present application also provides a switch cabinet cable discharge signal measurement and detection method, comprising the following steps:

S1: Collecting environmental noise information and transmitting the collected environmental noise information to a signal processing device;

S2: The conductive member transmits the partial discharge signal of the cable to the capacitive coupling unit, and the capacitive coupling unit filters the discharge signal to remove the frequency of the environmental noise band in the discharge signal;

S3: The capacitive coupling unit transmits the discharge signal after filtering out the environmental noise band to the amplifier;

S4: The amplifier receives the discharge signal, amplifies the discharge signal and outputs it;

S5: The signal processing device receives the amplified discharge signal and generates a processing result, which is used to display the cable discharge signal status.

It is understandable that in some embodiments, an indicator light or an audible and visual prompter is provided on the switch cabinet. When the cable discharge signal measuring device detects the discharge signal, a prompt is given through the indicator light or the audible and visual prompter. This can minimize the loss and aging of the switch cabinet caused by partial discharge. After partial discharge is detected, the affected cable can be immediately stopped from use to prevent further damage and danger, or the affected cable can be isolated and marked; or professional testing equipment can be used to thoroughly inspect and diagnose the cable, such as using a thermal imager to detect the temperature distribution of the cable to determine the location of the partial discharge. According to the results of the inspection and diagnosis, necessary repairs or replacements are made to the affected cable section. Preventive measures are taken to prevent similar problems from happening again. Preventive measures include improving maintenance plans, improving the insulation performance of cables, or strengthening monitoring and detection systems.

Specifically, test equipment such as a thermal imager can be installed in the switch cabinet to detect the cable in real time, or it can be independently set outside the switch cabinet. When the cable discharge signal measuring device detects the discharge signal, it is inspected and diagnosed through the test equipment.

The method of the present application can realize the discharge tracking and early warning of the switch cabinet simply, effectively and at low cost, and does not require the addition of additional sensor devices. It is suitable for the status monitoring of distribution equipment that is more sensitive to cost.

The present application can sensitively detect the partial discharge signal of the cable by arranging the conductive part in the insulating interlayer; by externally connecting a capacitive coupling unit and an amplifier to the conductive part and transmitting the signal to the capacitive coupling unit and the amplifier, it can suppress external interference signals and amplify the discharge signal, which helps to achieve better detection effects; by arranging the conductive part in the casing body, the integrated production and application of the casing and the conductive part are realized, which can improve the detection sensitivity while reducing the occupied space of the cable discharge signal measuring device.

The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims.

Claims (10)

1. A cable discharge signal measuring device, comprising:

the sleeve body is provided with an insulating interlayer;

the conductive piece is arranged in the insulating interlayer;

the capacitive coupling unit is connected with the conductive piece through a coaxial cable;

and the amplifier is connected with the capacitive coupling unit and is used for amplifying and outputting the discharge signal.

2. The cable discharge signal measurement device of claim 1 wherein the conductive member is a conductive polymer film, the conductive member comprises a base layer, a bonding layer and an electrode layer, the bonding layer is disposed between the base layer and the electrode layer, and electrode leads are embedded in the electrode layer.

3. The cable discharge signal measurement device of claim 1 wherein the conductive member is in the form of a ribbon, the conductive member being wrapped in the insulating interlayer.

4. The cable discharge signal measurement device of claim 1 wherein the sleeve body is provided with a signal wire slot, and the conductive member passes through the signal wire slot and is connected to the capacitive coupling unit.

5. The cable discharge signal measurement device of claim 4 wherein a retaining sleeve is disposed within the signal raceway, the retaining sleeve being configured to retain the conductive member, the conductive member being disposed within the retaining sleeve.

6. The cable discharge signal measurement device of claim 5, wherein a limiting member is disposed on an inner wall of the fixing sleeve, and the limiting member is capable of limiting the conductive member.

7. The cable discharge signal measurement device of claim 1 wherein the capacitive coupling unit is a capacitive or resistive-capacitive circuit element, the capacitive coupling unit being in parallel with the inner core of the coaxial cable.

8. The cable discharge signal measurement device of claim 1 wherein the amplifier is a transimpedance amplifier comprising one or more stages of amplifying circuitry.

9. A switchgear cabinet comprising a cabinet body and a cable discharge signal measuring device according to any one of claims 1-8, said cable discharge signal measuring device being mounted in said cabinet body.

10. The switchgear according to claim 9, characterized in that the switchgear has a bus bar compartment, a circuit breaker trolley compartment, a cable compartment and a relay instrument compartment, the bus bar compartment being provided with a bus bar, the bushing body being mounted on the bus bar, a connection plate being mounted on the bushing body, the bushing body being fixed in the bus bar compartment by means of the connection plate.