High voltage cable grounding arc test device based on reclosing

Abstract

A high-voltage cable grounding arc test device based on reclosing, wherein an insulation layer is wrapped on the outer surface of a core conductor, the insulation layer is provided with a connecting hole abutting the core conductor, a metal sheath is wrapped on the outer surface of the insulation layer, an arc copper wire is electrically connected to the core conductor through the connecting hole at one end and is electrically connected to the metal sheath at the other end, a first copper bar is arranged on the metal sheath at one end of the cable sample, and a second copper bar is arranged on the core conductor at the other end of the cable sample; a fixed rope is used to bind the cable sample and is fixed at both ends in a pair of grooves; a circuit breaker is connected to the second copper bar through a connecting cable; one end of a test power supply is connected to the circuit breaker through a current measuring device, and the other end is connected to the first copper bar, the test power supply comprises an impact generator, an impedance regulator and a transformer, and a voltage measuring device is connected in parallel to the test power supply and measures voltage data.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of high-voltage cable grounding arc test, in particular to a high-voltage cable grounding arc test device based on reclosing. BACKGROUND

[0002] Due to unexpected factors in the production, transportation and laying process of the cable, or the influence of the environment, the cable may produce local defects and further deteriorate during operation, leading to insulation breakdown and thus arc fault. Arc fault accounts for a large part of power equipment failure. The grounding arc current of high-voltage cable is high and the energy release is intense, which is extremely easy to cause fire accidents. Therefore, it is of great significance to study the cable grounding arc for the safe and stable operation of the power system.

[0003] In the prior art, the cable grounding arc test is mainly for distribution network cables of lower voltage grade. Due to the setting rules of relay protection of distribution network lines, when a grounding arc fault occurs, the circuit breaker usually does not perform reclosing operation after tripping. However, in high-voltage cable lines, the circuit breaker will still perform reclosing after tripping, thereby causing arc again. Therefore, the previous test device lacks the line reclosing process, and cannot test the reclosing arc, so the test cannot be completed. In addition, if the test is performed according to the actual operating conditions of high-voltage cables, a very high power voltage and current are required, which puts high requirements on the performance of the test power supply, and even the test cannot be performed, which makes the high-voltage cable grounding arc test more difficult to perform. Therefore, a high-voltage cable grounding arc test device considering reclosing is needed. SUMMARY

[0004] In order to solve the above technical problems, the present application provides a high-voltage cable grounding arc test device based on reclosing, which can realize the cable reclosing process through the circuit breaker, so that the test is completed and the electrical characteristics and morphological feature images of the high-voltage cable grounding arc are obtained. The present application can reduce the requirements on the test power supply.

[0005] The high-voltage cable grounding arc test device based on reclosing comprises:

[0006] a pair of tracks arranged at intervals and extending along a first direction;

[0007] a movable protective cover movably connected to the pair of tracks to cover the cable sample;

[0008] a pair of grooves arranged at intervals and located between the pair of tracks, the grooves extending along the first direction;

[0009] a cable support fixed between the pair of grooves;

[0010] a cable sample comprising,

[0011] wire core conductor;

[0012] an insulation layer wrapped on the outer surface of the wire core conductor, the insulation layer being provided with a connecting hole abutting the wire core conductor;

[0013] a metal sheath wrapped on the outer surface of the insulation layer;

[0014] an arc copper wire, one end of which is electrically connected to the wire core conductor via the connecting hole, and the other end of which is electrically connected to the metal sheath;

[0015] a first copper bar provided on the metal sheath at one end of the cable sample;

[0016] a second copper bar provided on the wire core conductor at the other end of the cable sample;

[0017] a fixing rope belt, which is used to bind the cable sample and is fixed at both ends to a pair of grooves;

[0018] a circuit breaker, which is connected to the second copper bar via a connecting cable;

[0019] a test power supply, one end of which is connected to the circuit breaker via a current measuring device, and the other end of which is connected to the first copper bar, the test power supply comprising an impulse generator, an impedance regulator and a transformer;

[0020] a voltage measuring device, which is connected in parallel to the test power supply and measures voltage data.

[0021] In the high-voltage cable grounding arc test device based on reclosing, the circuit breaker is closed, an arc is generated under the arc copper wire of the cable sample, then the circuit breaker is opened, the arc is extinguished, at this time, the reclosing time is entered, the voltage measuring device and the current measuring device synchronously measure the output voltage and current of the test power supply, the output voltage of the power supply is the voltage at both ends of the cable sample, and the output current of the power supply is the current flowing through the cable sample.

[0022] In the high-voltage cable grounding arc test device based on reclosing, two arc ignition times and one reclosing time, the circuit breaker is closed, an arc is generated under the arc copper wire of the cable sample, the first arc ignition starts at 0.05 s and lasts for about 0.55 s, the arc current passes through a transient component of 2.5 times of an effective value at the moment of closing, and is gradually stabilized to a 20 kA power frequency periodic waveform, in the reclosing time, the current is 0, and the voltage at both ends of the cable sample is the bus voltage of the power supply, after reclosing, the cable sample will be broken down again and cause arc ignition, and the arc ignition time is from 2.09 s to 2.19 s.

[0023] In the high-voltage cable grounding arc test device based on reclosing, the test power supply, the current measuring device, the circuit breaker and the cable sample constitute a loop.

[0024] In the aforementioned high-voltage cable grounding arc test device based on reclosing, the impedance regulator adjusts the current level of the circuit.

[0025] In the aforementioned high-voltage cable grounding arc test device based on reclosing, the test power supply adjusts the current and power supply and executes the test action via a controller.

[0026] In the high-voltage cable grounding arc test device based on reclosing, a semi-conductive strip covering the outer surface of the conductor core and a conductor shielding layer covering the outer surface of the semi-conductive strip are provided between the conductor core and the insulation layer, and the outer surface of the conductor shielding layer is wrapped by the insulation layer.

[0027] In the aforementioned high-voltage cable grounding arc test device based on reclosing, an insulating shielding layer and a water-blocking strip are provided between the insulating layer and the metal sheath, the outer surface of which are wrapped around the insulating layer and the metal sheath. The outer surface of the water-blocking strip is wrapped by the metal sheath.

[0028] In the aforementioned high-voltage cable grounding arc test device based on reclosing, the outer surface of the metal jacket is covered with an outer sheath.

[0029] In the aforementioned high-voltage cable grounding arc test device based on reclosing, the insulation layer comprises cross-linked polyethylene.

[0030] Compared with the prior art, the present invention has the following advantages:

[0031] The high-voltage cable grounding arc test device based on reclosing, while maximizing the reproduction of the high-voltage cable grounding arc, reduces the performance requirements of the test power supply and considers the reclosing process of high-voltage cable relay protection. It provides conditions for testing grounding arc faults caused by insulation degradation and breakdown of high-voltage cables, which is beneficial for studying power system transient processes and promotes power safety research. Attached Figure Description

[0032] The accompanying drawings illustrate exemplary embodiments of the invention and, together with the description thereof, serve to explain the principles of the invention. These drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification.

[0033] Figure 1 This is a schematic diagram of the high-voltage cable cross-section of a high-voltage cable grounding arc test device based on reclosing in one embodiment of the present invention;

[0034] Figure 2 This is a schematic diagram of the cable sample structure of a high-voltage cable grounding arc test device based on reclosing in one embodiment of the present invention;

[0035] Figure 3is a structure schematic diagram of a high-voltage cable grounding arc test device based on reclosing in an embodiment of the present application;

[0036] Figure 4 is a structure schematic diagram of a high-voltage cable grounding arc test device based on reclosing in an embodiment of the present application;

[0037] Figure 5 is a structure schematic diagram of a high-voltage cable grounding arc test device based on reclosing in an embodiment of the present application;

[0038] Figure 6 is a structure schematic diagram of a high-voltage cable grounding arc test device based on reclosing in an embodiment of the present application;

[0039] Figures 7(a) to 7(c) is a structure schematic diagram of a high-voltage cable grounding arc test device based on reclosing in an embodiment of the present application;

[0040] Figure 8 is a structure schematic diagram of a high-voltage cable grounding arc test device based on reclosing in an embodiment of the present application; DETAILED DESCRIPTION

[0041] The present application will be further described below in conjunction with the drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the related content, and not to limit the present application. In addition, it should be noted that only the parts related to the present application are shown in the drawings for ease of description.

[0042] It should be noted that the embodiments and features in the embodiments can be combined with each other in the present application without conflict. The technical solutions of the present application will be described in detail below with reference to the drawings and in conjunction with the embodiments.

[0043] Unless otherwise specified, the exemplary embodiments / examples shown will be understood as providing exemplary features of various details of some ways in which the technical ideas of the present application can be implemented in practice. Therefore, unless otherwise specified, the features of various embodiments / examples can be additionally combined, separated, interchanged and / or rearranged without departing from the technical ideas of the present application.

[0044] Cross-hatching and / or shading can be used in the drawings and is generally used to make the boundaries and regions of adjacent components more clearly understood. As such, unless specifically stated otherwise, the presence of cross-hatching or shading in a drawing is not a requirement for structural components, material properties, dimensions, ratios, etc. in actual implementations. In addition, the dimensions and relative dimensions of the various portions of the drawings are intended to be exaggerated for clarity. Numbers in the figures can correspond to the same or similar components throughout the figures and / or text.

[0045] When a component is referred to as being "on" or "over" another component, "connected to" or "coupled to" another component, it can be directly on, directly connected to, or directly coupled to the other component, or intervening components can be present. However, when a component is referred to as being "directly on", "directly connected to", or "directly coupled to" another component, there are no intervening components present. By the term "connected" is meant physical or electrical connection, with or without intervening components.

[0046] For descriptive purposes, the present application can use spatial or directional adjectives, such as "under", "below", "lower", "on", "above", "upper", "over", "higher", and "side" (e.g., as in "side wall"), to describe the relationship between one component and another (s) in the drawings. The spatial or directional adjectives are intended to encompass different orientations of the device in use, operation, and / or manufacture, other than the orientation depicted in the drawings. For example, if the device in the drawings is turned over, then a component described as "below" or "under" another component would then be oriented "above" the other component. Thus, an exemplary term "below" can encompass both an "above" and "below" orientation. Furthermore, the device can be oriented in different directions (e.g., rotated 90 degrees or at other orientations) and, as such, the spatial or directional adjectives used herein should be interpreted accordingly.

[0047] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. Furthermore, to the extent that the terms "comprise", "have", "contain", and / or "include" and variations thereof are used herein, such terms are intended to be inclusive, in an aspect, it is also noted that the terms "substantial", "approximately", and other similar terms are used as terms of approximation and not as terms of degree unless otherwise indicated herein, and accordingly, such terms are utilized on the basis and readily understood by those of ordinary skill in the art that there are inherent deviations in measurements, calculations and / or other sources of variations.

[0048] Referring to Figures 1 to 8 In one embodiment, the reclosing-based high-voltage cable grounding arc test device comprises:

[0049] a pair of rails 1 arranged at intervals and extending in a first direction;

[0050] a movable protective cover 2 movably connected to the pair of rails 1 to cover the cable sample 5;

[0051] a pair of grooves 3 arranged at intervals and located between the pair of rails 1, the grooves 3 extending in the first direction;

[0052] a cable support 4 fixed between the pair of grooves 3;

[0053] a cable sample 5 comprising,

[0054] a core conductor 6;

[0055] an insulation layer 7 wrapped on the outer surface of the core conductor 6, the insulation layer 7 being provided with a connecting hole 8 abutting the core conductor 6;

[0056] a metal sheath 9 wrapped on the outer surface of the insulation layer 7;

[0057] an arc copper wire 10 having one end electrically connected to the core conductor 6 via the connecting hole 8 and the other end electrically connected to the metal sheath 9;

[0058] a first copper bar 11 provided at the metal sheath 9 of one end of the cable sample 5;

[0059] a second copper bar 12 provided at the core conductor 6 of the other end of the cable sample 5;

[0060] a fixed rope 13 binding the cable sample 5 and fixed at both ends to the pair of grooves 3;

[0061] a circuit breaker 14 connected to the second copper bar 12 via a connecting cable 21;

[0062] a test power supply 15 connected to the first copper bar 11 at one end and to the circuit breaker 14 via a current measuring device at the other end, the test power supply 15 comprising an impulse generator, an impedance regulator and a transformer,

[0063] a voltage measuring device connected in parallel to the test power supply 15 and measuring voltage data.

[0064] In the preferred embodiment of the reclosing-based high voltage cable earth arc test device, the circuit breaker 14 is closed, an arc is generated in the cable sample 5 under the arc copper 10 and then the circuit breaker 14 is opened, the arc is extinguished, at this time the reclosing time is entered, the voltage measuring device and the current measuring device synchronously measure the output voltage and current of the test power supply 15, the output voltage of the power supply is the voltage across the cable sample 5, and the output current of the power supply is the current flowing through the cable sample 5.

[0065] In the preferred embodiment of the reclosing-based high voltage cable earth arc test device, two arcing times and one reclosing time, the circuit breaker 14 is closed, an arc is generated in the cable sample 5 under the arc copper 10, the first arcing time starts at 0.05s and lasts to about 0.55s, the arc current has a transient component of 2.5 times the effective value at the moment of closing, and gradually stabilizes to a 20kA power frequency periodic waveform, in the reclosing time, the current is 0, and the voltage across the cable sample 5 is the bus voltage of the power supply, after reclosing, the cable sample 5 will be broken down again and cause arcing, the arcing time is from 2.09s to 2.19s.

[0066] In the preferred embodiment of the reclosing-based high voltage cable earth arc test device, the test power supply 15, the current measuring device, the circuit breaker 14 and the cable sample 5 form a loop.

[0067] In the preferred embodiment of the reclosing-based high voltage cable earth arc test device, the impedance regulator adjusts the current level of the loop.

[0068] In the preferred embodiment of the reclosing-based high voltage cable earth arc test device, the test power supply 15 adjusts the current and power supply via a controller and performs test actions.

[0069] In the preferred embodiment of the reclosing-based high voltage cable earth arc test device, a semiconductive tape 16 wrapping the outer surface of the core conductor 6 and a conductor shielding layer 17 wrapping the outer surface of the semiconductive tape 16 are provided between the core conductor 6 and the insulating layer 7, and the outer surface of the conductor shielding layer 17 is wrapped via the insulating layer 7.

[0070] In a preferred embodiment of the high-voltage cable grounding arc test device based on reclosing, an insulating shielding layer 18 and a water-blocking tape 19 are provided between the insulating layer 7 and the metal sheath 9, the insulating shielding layer 7 being wrapped with the outer surface of the insulating layer 7 and the metal sheath 9 being wrapped with the outer surface of the water-blocking tape 19 being wrapped with the metal sheath 9.

[0071] In a preferred embodiment of the high-voltage cable grounding arc test device based on reclosing, the outer surface of the metal jacket is covered with an outer sheath 20.

[0072] In a preferred embodiment of the high-voltage cable grounding arc test device based on reclosing, the insulation layer 7 comprises cross-linked polyethylene.

[0073] In one embodiment, a high-speed camera is also included, directed toward the arc-starting copper wire 10 to capture the arc.

[0074] In one embodiment, the length of the cable sample 5 to be tested is 2 meters. Since the cable grounding arc occurs in the air gap of the cable insulation layer 7, therefore... Figure 2 As shown, the cross-linked polyethylene insulation layer 7 is stripped through the center of cable sample 5, and a connecting hole 8 is drilled in it, reaching the core conductor 6. A 0.5mm arc-starting copper wire 10 is used to connect the core conductor 6 to the metal sheath 9, and this point is used as the arc-starting point. Since cable sample 5 is to be connected to the circuit, its electrical contact point needs to withstand a high short-circuit current, so a cable joint needs to be made. One end of the cable is stripped through to the metal sheath 9, and a first copper busbar 11 is installed on the metal sheath 9 as a cable joint; the other end is stripped layer by layer through to the cross-linked polyethylene insulation layer 7 and the core conductor 6, and a second copper busbar 12 is installed on the core conductor 6 as a cable joint.

[0075] In one embodiment, the processed cable sample 5 is placed on the cable support 4 and secured with a fixing rope 13. Both ends of the rope 13 are fixed in grooves 3 in the ground to ensure that the cable sample 5 will not tip over due to electrodynamic forces during the test. One end of the conductor 6 of the cable sample 5 is connected to the circuit breaker 14 via a connecting cable. The movable protective cover 2 can move along the grooves 3 in the ground; pushing the movable protective cover 2 covers the cable sample 5 to ensure test safety.

[0076] In one embodiment, one end of the test power supply 15 is connected to the circuit breaker 14 after passing through a current measuring device, and then connected to the conductor 6 of the cable sample 5 via a connecting cable through the circuit breaker 14. The metal sheath 9 on the other side of the cable is connected back to the other side of the test power supply 15 and grounded on that side. A voltage measuring device is connected in parallel across the two ends of the test power supply 15.

[0077] In one embodiment, the test power supply 15 of the present application is composed of a large capacity impulse generator, an impedance regulator and a transformer, wherein the large capacity impulse generator can provide the short-circuit power requirement in a short time, the impedance regulator can set the current level of the adjustment loop, and the transformer is used to adjust the output voltage of the test power supply 15. The above three devices can complete the setting and corresponding action under the control of computer software. The test power supply 15 is usually set according to the actual operating conditions of the cable, but in the ground arc test of high-voltage cable, most power supplies cannot reach the actual short-circuit capacity. Considering that the thermal effect of arc mainly comes from short-circuit current, the power supply voltage can be reduced to a level sufficient to maintain the arc, and the current is the same as the actual short-circuit current, that is, the required power supply capacity of the test is reduced. In addition, considering the transient process during short-circuit, according to the relevant standards, the peak value of short-circuit current at the moment of test closing can be set to 2.5 times the effective value, and the high-voltage DC cable is set to 1.7 times the short-circuit current level. When the short-circuit current level is determined, the test power supply 15 can output the current according to the required requirements by controlling the current.

[0078] When the test starts, the circuit breaker 14 is closed, the cable sample 5 generates an arc at the arc initiation point, and the initial arc ignition time can be selected from 0.1s, 0.3s or 0.5s. Then the circuit breaker 14 is opened, and the arc is extinguished. At this time, the reclosing time is entered, which can be set according to the specific line condition. After the reclosing time elapses, the circuit breaker 14 is reclosed, and the cable sample 5 is ignited again. The reclosing arc ignition time is generally short, so it can be set to 0.1s. After that, the circuit breaker 14 is opened, and the test is ended. When the test is carried out, the voltage measuring device and the current measuring device measure the output voltage and current of the power supply synchronously. The output voltage of the power supply is the voltage across the cable sample 5, and the output current of the power supply is the current flowing through the cable sample 5.

[0079] Embodiment 1

[0080] The voltage and current curves of the 110kV high-voltage AC cable sample 5 obtained by using the test device are as follows: Figures 7(a) to 8The test process is divided into two arcing time and one reclosing time. The first arcing time is about 0.05s, and lasts to about 0.55s. The arc current passes a transient component of about 2.5 times of the effective value at the moment of closing, and gradually stabilizes to a 20kA power frequency periodic waveform, which meets the requirements of arc test. The voltage distortion degree is large, and the peak value of the voltage is no longer a platform, but slightly convex upward, which is due to the strong thermal effect of the large current arc, which makes the resistance quickly drop to a very small resistance value after the current zero point, so the voltage produces a convex corner on the top after the sudden increase. In the reclosing time, the current is 0 due to the disconnection of the loop, and the voltage across the sample is the bus voltage. After reclosing, the cable sample 5 will be broken down again and cause arcing, and the arcing time is about from 2.09s to 2.19s.

[0081] In the description of the present specification, the description of the terms "one embodiment / way", "some embodiments / ways", "example", "specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment / way or example are included in at least one embodiment / way or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment / way or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments / ways or examples. In addition, the person skilled in the art can combine and combine the different embodiments / ways or examples described in the present specification and the features of the different embodiments / ways or examples without contradiction.

[0082] In addition, the terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "a plurality of" is at least two, for example, two, three, etc., unless otherwise specifically limited.

[0083] Those skilled in the art should understand that the above embodiments are only for clearly illustrating the present application, and are not intended to limit the scope of the present application. Based on the above disclosure, other changes or modifications can also be made by those skilled in the art, and these changes or modifications are still within the scope of the present application.

Claims

1. A reclosing-based high-voltage cable earth arc test device, characterized in that It comprises: a pair of tracks arranged at intervals and extending along a first direction; a movable protective cover movably connected to the pair of tracks to cover the cable sample; a pair of grooves arranged at intervals and located between the pair of tracks, the grooves extending along the first direction; a cable support fixed between the pair of grooves; a cable sample comprising, a core conductor; an insulating layer wrapped on the outer surface of the core conductor, the insulating layer being provided with a connecting hole abutting the core conductor; a metal sheath wrapped on the outer surface of the insulating layer; an arc copper wire, one end of which is electrically connected to the core conductor through the connecting hole, and the other end of which is electrically connected to the metal sheath; a first copper bar provided on the metal sheath at one end of the cable sample; a second copper bar provided on the core conductor at the other end of the cable sample; a fixing rope band binding the cable sample and fixed at both ends to the pair of grooves; a circuit breaker connected to the second copper bar through a connecting cable; a test power supply, one end of which is connected to the circuit breaker through a current measuring device, and the other end of which is connected to the first copper bar, the test power supply comprising an impulse generator, an impedance regulator and a transformer; a voltage measuring device connected in parallel to the test power supply and measuring voltage data; wherein the circuit breaker is closed, an arc is generated under the arc copper wire of the cable sample, then the circuit breaker is opened, the arc is extinguished, at this time the reclosing time is entered, the voltage measuring device and the current measuring device synchronously measure the output voltage and current of the test power supply, the output voltage of the power supply is the voltage across the cable sample, and the output current of the power supply is the current flowing through the cable sample; two arc burning times and one reclosing time, the circuit breaker is closed, an arc is generated under the arc copper wire of the cable sample, the initial arc burning starts at 0.05s and lasts to about 0.55s, the arc current has a transient component of 2.5 times the effective value at the moment of closing, and gradually stabilizes to a 20kA power frequency periodic waveform, in the reclosing time, the current is 0, and the voltage across the cable sample is the bus voltage of the power supply, after reclosing, the cable sample will be broken down again and cause arc burning, the arc burning time is from 2.09s to 2.19s.

2. The reclosing based high voltage cable earthing arc testing device according to claim 1, characterized in that, The test power supply, the current measuring device, the circuit breaker and the cable sample constitute a loop.

3. The reclosing based high voltage cable earthing arc testing device according to claim 2, characterized in that, The impedance regulator adjusts the current level of the loop.

4. The reclosing-based high-voltage cable earthing arc test device according to claim 1, characterized in that The test power supply adjusts the current and power supply through the controller and performs test actions.

5. The reclosing-based high-voltage cable earthing arc test device according to claim 1, characterized in that, A semiconductive tape wrapped on the outer surface of the core conductor and a conductor shielding layer wrapped on the outer surface of the semiconductive tape are provided between the core conductor and the insulating layer, and the outer surface of the conductor shielding layer is wrapped through the insulating layer.

6. The reclosing-based high-voltage cable earthing arc test device according to claim 1, characterized in that, An insulating shielding layer wrapped on the outer surface of the insulating layer and a water-blocking tape wrapped on the insulating shielding layer are provided between the insulating layer and the metal sheath, and the outer surface of the water-blocking tape is wrapped through the metal sheath.

7. The reclosing-based high-voltage cable earthing arc testing device according to claim 1, characterized in that, The outer surface of the metal sheath is wrapped with an outer sheath.

8. The reclosing-based high-voltage cable earthing arc testing device according to claim 1, characterized in that, The insulating layer comprises cross-linked polyethylene.

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