CN213750168U - Cable partial discharge simulation device - Google Patents
Cable partial discharge simulation device Download PDFInfo
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- CN213750168U CN213750168U CN202022876062.2U CN202022876062U CN213750168U CN 213750168 U CN213750168 U CN 213750168U CN 202022876062 U CN202022876062 U CN 202022876062U CN 213750168 U CN213750168 U CN 213750168U
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Abstract
The utility model discloses a cable partial discharge analogue means, including autotransformer T1High voltage transformer T2A current-limiting protection resistor R, a first capacitor C1And a second capacitor C2Form a capacitive voltage divider and a partial discharge defect model CxThe high-frequency current sensor D, the signal conditioning circuit, the signal acquisition module and the signal processing circuit are connected with the signal processing circuit; providing analog high voltage by the autotransformer and the high voltage transformer, and measuring the second capacitance C of the capacitive divider2Obtaining power frequency phase from voltage at two ends, and collecting signal with oscilloscopeThe module collects front-end signals, the computer communicates with the oscilloscope through a network port, the computer is used for storing the collected signals and finishing subsequent signal processing work, a reliable partial discharge simulation device is provided for teaching, tests and the like, the practicability is high, partial discharge phenomena of different types are simulated, and various test requirements are met.
Description
Technical Field
The utility model relates to a cable fault testing technique, concretely relates to cable partial discharge analogue means.
Background
The definition of partial discharge in the standard GB/T7354-2018 "measurement of partial discharge in high voltage testing technology" is "electrical discharge in which the insulation between conductors is only partially bridged", and the position of occurrence of partial discharge is also defined, i.e. "may or may not occur near a conductor". That is, the partial discharge phenomenon is a phenomenon in which the insulating dielectric portion is defective and not broken down as a whole. The phenomenon of early discharge is very weak, and the influence on the insulation performance is not serious, but partial discharge is developed to the later stage, the insulation medium is further degraded, and the breakdown phenomenon can be generated in the insulation medium, so that the cable fault is generated, and the power accident is caused.
The partial discharge of the power cable insulation is mainly caused by the following three aspects. On one hand, in the manufacturing process of the cable insulating medium, even under a higher manufacturing process and a higher manufacturing level, the perfect degree cannot be achieved, various impurities are inevitably introduced, the conductivity of the impurities is greatly different from that of the surrounding insulating medium, the dielectric constant of the impurities is lower, and when voltage is applied to the outside, the partial discharge phenomenon is more easily caused. On the other hand, during the transportation and installation processes of the cables, the insulation of the cables is damaged due to incorrect transportation modes, such as high-altitude cable throwing, flat cable placing, mutual collision among the cables and the like; when the cable is installed on site, partial discharge may occur in a wrong installation process, such as irregular installation of individual parts of the cable caused by wrong operations of an installer. Moreover, because the cable is usually directly buried underground, or laid underground in a pipeline or channel mode, in the operation process of the cable, cracks can be generated inside an insulating medium of the cable due to local excessive mechanical stress, water branches can be generated inside the insulating medium due to severe environments such as surrounding soil, moisture and the like, and the partial discharge phenomenon can be caused after long-term development.
The power cable insulation medium is damaged in different types and positions, and the partial discharge type and the discharge characteristics of the power cable insulation medium are different, and mainly comprise internal discharge, surface discharge and corona discharge.
(1) Internal discharge
The internal discharge of the power cable mainly refers to a partial discharge phenomenon caused by bubbles, cracks or other impurities inside the insulating medium. The bubbles generated inside the insulating medium are caused by many reasons, which may be present during the production of the cable or may be local cracks due to external pressure. The main reason for the internal discharge is that the electric field strength is large and the breakdown voltage is small in the bubble. Therefore, when the external voltage is increased, the insulating medium still maintains good insulating characteristics, and the air bubbles can break down before the insulating medium, thereby causing the generation of the partial discharge phenomenon. The internal discharge generally occurs in the phase of the voltage rise of the first quadrant and the third quadrant of the cable power frequency period, and whether the discharge pulse signals are symmetrical in the three quadrants is closely related to the information of the impurity type, the impurity position, the structure and the like in the medium.
(2) Creeping discharge
At the interface of different media, the electric field can be decomposed into an electric field perpendicular to the interface and an electric field parallel to the interface. Creeping discharge refers to a discharge phenomenon that occurs when the electric field strength parallel to the interface is high, and it can be broken down. Creeping discharges often occur between the insulating medium and the surface of the metal layer, such as the ends of cables and poorly mounted electrodes. The creeping discharge phenomenon mainly occurs between 0 ° to 90 ° and 180 ° to 270 ° as with the internal discharge. However, when the electrode is asymmetric, the creeping discharge spectrogram also presents asymmetry, and particularly when creeping discharge occurs on a high-potential electrode, the discharge frequency of the first quadrant is higher, the pulse amplitude is lower, and the pulse amplitude of the third quadrant is higher, but the discharge frequency is lower.
(3) Corona discharge
The corona discharge is a phenomenon that local discharge occurs in a surrounding air medium due to the fact that a high-voltage conductor is exposed in air and the electric field intensity near the high-voltage conductor is high, and the breakdown field intensity of the air is achieved. Corona discharge often occurs in metal areas with small radii of curvature, such as switchgear busbars, high voltage cable intermediate joints, and transmission line connections. During a power frequency period, multiple corona discharges may occur, and the larger the externally applied voltage, the more the discharges occur, but the discharge amplitude remains the same. The initial voltage of corona discharge is related to the externally applied voltage, the positive and negative nature of the tip and the shape of the conductor, and the discharge waveform has high asymmetry. For a high voltage conductor, a negative polarity electrode, corona discharge will first occur near the third quadrant peak of the voltage. The partial discharge pulse will only occur in the first quadrant if the voltage continues to increase to some extent.
The simulation device simulates partial discharge phenomena of various types of cables and has important significance on cable manufacturing construction and partial discharge research.
SUMMERY OF THE UTILITY MODEL
An object of the utility model is to provide a cable partial discharge analogue means can simulate each type cable partial discharge phenomenon, puts the phenomenon for studying the cable office and provides theoretical support.
In order to achieve the above object, the utility model adopts the following technical scheme:
a cable partial discharge simulator comprises an autotransformer T1High voltage transformer T2A current-limiting protection resistor R, a first capacitor C1And a second capacitor C2Form a capacitive voltage divider and a partial discharge defect model CxThe high-frequency current sensor D, the signal conditioning circuit, the signal acquisition module and the signal processing circuit are connected with the signal processing circuit;
the autotransformer T1After being connected with 220V commercial power, the high-voltage transformer T2Low voltage end connected, high voltage transformer T2The high-voltage end is connected with the first capacitor C after being connected with the current-limiting protection resistor R1A second capacitor C2Capacitive voltage divider parallel connection formed by series connection and partial discharge defect model CxThe signal conditioning circuit is connected with the high-frequency current sensor D, and the signal acquisition module and the signal processing circuit are connected with the high-frequency current sensor D;
the partial discharge defect model CxComprises a high-voltage electrode and a grounding electrode which are oppositely and movably arranged on two insulation supporting plates, and an intermediate insulation material is arranged between the two electrodes; by measuring the second capacitance C2Acquiring power frequency phase from voltages at two ends, acquiring front end signal by using oscilloscope as signal acquisition module, communicating with oscilloscope by using network interface, and storing and acquiringAnd the subsequent signal processing work is completed.
Furthermore, the auto-coupling voltage regulator adopts a high-voltage operation box, the output voltage range is 0-250V, and the capacity is 3 kVA.
Further, the high-voltage transformer adopts an alternating current-direct current high-voltage test transformer.
Furthermore, the supporting plates are made of two pieces of organic glass with the same size, the distance between the supporting plates is adjustable, the supporting plates are fixed on the periphery, and the high-voltage electrode and the grounding electrode are respectively connected with the two supporting plates through studs arranged in the middle of the supporting plates.
Further, when the bubble discharges in the simulation cable, the high-voltage electrode adopts a spherical structure, the grounding electrode adopts a flat plate structure, or the two electrodes adopt plate structures, the middle insulating material adopts a three-layer insulating plate structure adhered together, wherein the upper layer and the lower layer are complete insulating plate structures, and the middle layer is dug to form a round hole.
Further, when creeping discharge is simulated, the high-voltage electrode adopts a columnar electrode, the grounding electrode adopts a circular plate electrode, and the middle insulating material adopts a single-layer insulating plate structure.
Furthermore, when the corona discharge is simulated, the high-voltage electrode adopts a needle-shaped structure, the grounding electrode adopts a flat plate structure, the middle insulating material adopts a single-layer insulating plate structure, and a gap with a certain distance is reserved between the needle electrode and the insulating plate.
Compared with the prior art, the beneficial effects of the utility model are that:
the utility model discloses an autotransformer and high voltage transformer provide simulation high voltage electricity, through measuring capacitive voltage divider's second electric capacity C2The voltage at two ends obtains a power frequency phase, the oscilloscopes are used as signal acquisition modules to acquire front-end signals, the computer is communicated with the oscilloscopes through a network port and is used for storing the acquired signals and finishing subsequent signal processing work, a reliable partial discharge simulation device is provided for teaching, tests and the like, the practicability is high, partial discharge phenomena of different types are simulated, and various test requirements are met.
Furthermore, the organic glass is used for manufacturing the supporting plate, the threads are arranged in the middle of the supporting plate, the electrodes with different structures are connected through the studs, the distance between the electrodes can be changed by rotating the nuts, the discharging position can be changed, different insulation defects are placed in the middle of the electrodes, the installation is convenient, the disassembly is convenient, and the test efficiency is greatly improved; the device can be matched with various partial discharge detection devices to carry out the work of research and development, skill training, instrument verification and comparison and the like of the partial discharge detection technology of the switch cabinet device.
Drawings
FIG. 1 schematic diagram of power cable experiment
FIG. 2 is a schematic view of a bubble discharge model
FIG. 3 schematic diagram of surface discharge model
FIG. 4 is a schematic view of a corona discharge model
In the figure: 1-high voltage electrode, 2-grounding electrode, 3-intermediate insulating material and 4-support plate.
Detailed Description
The present invention will be described in further detail with reference to the following specific examples, which should not be construed as limiting the invention.
As shown in FIG. 1, a cable partial discharge simulation device, T, was constructed1Is a self-coupled voltage regulator, T2Is a high-voltage transformer, R is a current-limiting protection resistor with the resistance value of 10k omega, and a first capacitor C1A second capacitor C2Form a capacitive voltage divider, and C1＜＜C2It is possible to measure the second capacitance C2Obtaining power frequency phase, C, from voltage at two endsxThe signal acquisition module selects an RTB 2004 oscilloscope as a front-end acquisition part, and the computer communicates with the oscilloscope by using a network port, stores the acquired signals and completes subsequent signal processing work.
Autotransformer T1After being connected with 220V commercial power, the high-voltage transformer T2Low voltage end connected, high voltage transformer T2The high-voltage end is connected with the first capacitor C after being connected with the current-limiting protection resistor R1A second capacitor C2Capacitive voltage divider parallel connection formed by series connection and partial discharge defect model CxA high-frequency current sensor D connected in series and then connected in parallel with the capacitive voltage divider, a signal conditioning circuit and the high-frequency current sensorThe device D is connected, and the signal acquisition module and the signal processing circuit are connected with the high-frequency current sensor D.
The self-coupling voltage regulator adopts an XCJH-3 series high-voltage operating box, the output voltage range is 0-250V, the capacity is 3kVA, the voltage regulator can be adjusted by rotating a handle on a panel, and the voltage is output to a transformer end to obtain a target high-voltage value. The high-voltage transformer selects the YDJZ series light alternating current-direct current high-voltage test transformer, and needs to use 50Hz power frequency voltage in the experimental process, so that when the transformer is used, a short circuit rod needs to be connected, and the high-voltage silicon stack is in short circuit to serve as an alternating current output state. For safety, after each experiment, the system must be discharged by using a discharge rod.
When the discharge model is manufactured, firstly two supporting plates with the same size are manufactured by using organic glass, the distance between the two supporting plates is adjustable, and the two supporting plates are fixed at the periphery. Then, threads are arranged in the middle of the supporting plate, electrodes with different structures are connected through a stud, and the distance between the electrodes is changed through rotating a nut. And finally, different insulation defects are placed in the middle of the electrode to simulate different types of partial discharge phenomena.
The cable insulation medium is damaged at different positions, the partial discharge type and the discharge characteristic are different, and the common defects are three. According to the discharge nature and discharge characteristics of different discharge types, corresponding equivalent models can be made in a laboratory to simulate the discharge nature and the discharge characteristics, and the corresponding relationship is shown in table 1.
TABLE 1 Cable partial discharge type and equivalent model thereof
Three partial discharge defect models are described below:
(1) bubble discharge
The bubble discharges inside the cable are usually caused by bubbles, cracks or other impurities inside the insulating medium. When simulating the partial discharge type, the high-voltage electrode adopts a spherical structure, the grounding electrode adopts a flat plate structure, or the two electrodes adopt a plate structure, and the air bubbles adopt a three-layer insulation plate structure, wherein the upper layer and the lower layer are complete insulation plate structures, and the round holes are dug in the middle layer to simulate the air bubbles in an insulation medium and simultaneously adopt insulating glue to adhere the air bubbles together. A ball-plate electrode is selected during manufacturing, a defect model and a manufactured object of the ball-plate electrode are shown in figure 2, wherein the high-voltage electrode is a ball-shaped electrode with the diameter of 6mm, the middle bubble material is made of three layers of epoxy resin round plates with the diameter of 100mm and the thickness of 0.5mm, a round hole with the diameter of 15mm is dug in the middle layer, epoxy glue is used for bonding the layers, a round plate electrode is used as a grounding electrode, the diameter of the electrode is 100mm, and the thickness of the electrode is 10 mm.
(2) Creeping discharge
Creeping discharge tends to occur at the interface of the insulating medium and the metal layer. The creeping discharge model adopts a flat plate structure or a column-plate structure, and the discharge defect adopts a single-layer insulation plate structure. The manufacturing method adopts a column-plate structure, and a defect model and a manufacturing object thereof are shown in fig. 3, wherein the high-voltage electrode adopts a column electrode with the diameter of 25mm, the grounding electrode adopts a circular plate electrode, all parameters are kept unchanged, the middle insulating medium adopts a polyimide film material, and the thickness is 0.05 mm.
(3) Corona discharge
Corona discharge often occurs in metal areas with small radii of curvature, such as sharp corners, bumps, or burrs, and so can be equated with a pin-and-plate model. The discharge type high-voltage electrode adopts a needle-shaped structure, the grounding electrode adopts a flat plate structure, an insulating plate is covered on the grounding electrode, a gap with a certain distance is reserved between the needle electrode and the insulating plate, a defect model and a manufacturing object are shown in figure 4, wherein the high-voltage electrode adopts the needle-shaped electrode, the needle point diameter is 1mm, the tip angle is 15 degrees, the insulating medium adopts a polyimide film material, the thickness is 0.05mm, the distance between the high-voltage electrode and the polyimide film is 3mm, the grounding electrode adopts a circular plate electrode, and all parameters are kept unchanged.
Before the partial discharge test, the three manufactured defect models need to be cleaned, so that the interference of defects such as tips, tiny dust, moisture and the like on the surface of the electrode is reduced. After the elimination of these interferences,and installing the partial discharge defect, and performing test connection. Slowly rotating the knob of the high-voltage operation box, observing the waveform of the oscilloscope, and recording the discharge voltage at the moment as the discharge starting voltage U when a discharge signal appears0Continuing to increase the voltage until the partial discharge model breaks down, and recording the discharge voltage at the moment as breakdown voltage Ub. When detecting the partial discharge defect, the test voltage is larger than U0Less than 0.9UbAnd when the stable discharge phenomenon exists, the stable discharge phenomenon is collected and transmitted to the computer for storage.
The present invention has been described in detail with reference to the above embodiments, and it will be understood by those of ordinary skill in the art that: modifications and equivalents may be made to the embodiments of the invention without departing from the spirit and scope of the invention, which is intended to be covered by the claims.
Claims (7)
1. A cable partial discharge simulation device is characterized in that: comprising a self-coupled voltage regulator T1High voltage transformer T2A current-limiting protection resistor R, a first capacitor C1And a second capacitor C2Form a capacitive voltage divider and a partial discharge defect model CxThe high-frequency current sensor D, the signal conditioning circuit, the signal acquisition module and the signal processing circuit are connected with the signal processing circuit;
the autotransformer T1After being connected with 220V commercial power, the high-voltage transformer T2Low voltage end connected, high voltage transformer T2The high-voltage end is connected with the first capacitor C after being connected with the current-limiting protection resistor R1A second capacitor C2Capacitive voltage divider parallel connection formed by series connection and partial discharge defect model CxThe signal conditioning circuit is connected with the high-frequency current sensor D, and the signal acquisition module and the signal processing circuit are connected with the high-frequency current sensor D;
the partial discharge defect model CxComprises a high-voltage electrode (1) and a grounding electrode (2) which are oppositely and movably arranged on two insulation supporting plates (4), and an intermediate insulation material (3) is arranged between the two electrodes; by passingMeasuring a second capacitance C2The voltage at two ends obtains a power frequency phase, an oscilloscope is used as a signal acquisition module to acquire a front end signal, a computer is communicated with the oscilloscope by a network port, and the computer is used for storing the acquired signal and finishing subsequent signal processing work.
2. The cable partial discharge simulation apparatus of claim 1, wherein: the autotransformer adopts a high-voltage operation box, the output voltage range is 0-250V, and the capacity is 3 kVA.
3. The cable partial discharge simulation apparatus of claim 1, wherein: the high-voltage transformer adopts an AC/DC high-voltage test transformer.
4. The cable partial discharge simulation apparatus according to claim 2 or 3, wherein: the supporting plate (4) is made of two pieces of organic glass with the same size, the distance between the supporting plates is adjustable, the supporting plates are fixed on the periphery, and the high-voltage electrode (1) and the grounding electrode (2) are respectively connected with the two supporting plates (4) through studs arranged in the middle of the supporting plates.
5. The cable partial discharge simulation apparatus of claim 4, wherein: when the bubble discharges in the simulation cable, the high-voltage electrode adopts a spherical structure, the grounding electrode adopts a flat plate structure, or the two electrodes adopt plate structures, the middle insulating material adopts a three-layer insulating plate structure adhered together, wherein the upper layer and the lower layer are complete insulating plate structures, and the middle layer is dug to form a round hole.
6. The cable partial discharge simulation apparatus of claim 4, wherein: when the creeping discharge is simulated, the high-voltage electrode adopts a columnar electrode, the grounding electrode adopts a circular plate electrode, and the middle insulating material is in a single-layer insulating plate structure.
7. The cable partial discharge simulation apparatus of claim 4, wherein: when simulating corona discharge, the high-voltage electrode adopts a needle-shaped structure, the grounding electrode adopts a flat plate structure, the middle insulating material adopts a single-layer insulating plate structure, and a gap with a certain distance is reserved between the needle electrode and the insulating plate.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202022876062.2U CN213750168U (en) | 2020-12-04 | 2020-12-04 | Cable partial discharge simulation device |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202022876062.2U CN213750168U (en) | 2020-12-04 | 2020-12-04 | Cable partial discharge simulation device |
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| CN213750168U true CN213750168U (en) | 2021-07-20 |
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| CN202022876062.2U Expired - Fee Related CN213750168U (en) | 2020-12-04 | 2020-12-04 | Cable partial discharge simulation device |
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- 2020-12-04 CN CN202022876062.2U patent/CN213750168U/en not_active Expired - Fee Related
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Granted publication date: 20210720 Termination date: 20211204 |