CN113851990A - Method for replacing box-type transformer with low-voltage side completely uninterrupted - Google Patents
Method for replacing box-type transformer with low-voltage side completely uninterrupted Download PDFInfo
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02B—BOARDS, SUBSTATIONS OR SWITCHING ARRANGEMENTS FOR THE SUPPLY OR DISTRIBUTION OF ELECTRIC POWER
- H02B3/00—Apparatus specially adapted for the manufacture, assembly, or maintenance of boards or switchgear
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02G—INSTALLATION OF ELECTRIC CABLES OR LINES, OR OF COMBINED OPTICAL AND ELECTRIC CABLES OR LINES
- H02G1/00—Methods or apparatus specially adapted for installing, maintaining, repairing or dismantling electric cables or lines
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/381—Dispersed generators
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P80/00—Climate change mitigation technologies for sector-wide applications
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Abstract
The invention provides a box type transformer replacing method with a low-voltage side completely uninterrupted, wherein a low-voltage temporary mobile power supply is used for supplying power to a low-voltage terminal user during replacement of an original box transformer substation during replacement of the box type transformer, so that accompanying and stopping are avoided. The substantial effects of the invention include: the low-voltage cable branch box and the medium and low-voltage terminal users on the power supply link of the box-type transformer are powered by adopting a mode of connecting a low-voltage temporary mobile power supply twice, and then are switched back to the box-type transformer to supply power by adopting a hot-down mode, the whole process is completely uninterrupted, compared with the normal power failure, the box-type transformer is replaced for at least several hours, all the low-voltage terminal users accompany and stop until the box-type transformer is replaced, the loss of the number of users during the low-voltage accompanying and stopping is greatly reduced, and the reliability of low-voltage power supply and the power operator environment are effectively improved. Brings great economic benefit and social benefit for enterprises.
Description
Technical Field
The invention relates to the field of distribution network operation and maintenance, in particular to a method for replacing a box-type transformer with a low-voltage side completely without power outage.
Background
The box-type transformer is a complete set of distribution equipment which combines high-voltage switch equipment, a transformer and low-voltage distribution equipment into a whole according to a certain wiring scheme. As shown in fig. 1, in a general box-type transformer structure, a power supply is input through a high-voltage side high-voltage switch, and after voltage transformation is performed through a fusion tube and a box-type transformer body, a plurality of low-voltage outgoing lines are formed in the form of low-voltage side low-voltage main switches, low-voltage busbars and low-voltage branch lines cables to a plurality of low-voltage cable branch boxes arranged nearby low-voltage terminal users on site, and then the low-voltage cable branch boxes supply power to the low-voltage terminal users in the form of cables or overhead cable hybrid lines. Common low-voltage cable branch boxes are generally arranged in green belts of a community or at a position close to downstairs of a unit building.
Generally, the low-voltage end users of the box-type transformer have and only have one upper power supply, namely the box-type transformer, as the only power supply, and supply power to a plurality of low-voltage end users in a radial structure.
Generally, through years of use, when a box-type transformer needs to be replaced and maintained due to equipment operation or needs to be integrally transferred due to urban construction, for a low-voltage terminal user, accompanying power failure is caused due to integral replacement, maintenance and transfer of a superior incoming line power supply. Moreover, a common service object of a mode of converting medium-voltage power distribution into low-voltage power supply like a common box-type transformer is the masses of residents and small and micro businesses which are closely related to the residents, once the box-type transformer is overhauled, moved and modified, the satisfaction degree of electricity utilization of a large number of the residents and the users can be seriously influenced, complaints are brought to power supply enterprises, and the formation of a good operator environment is not facilitated.
Disclosure of Invention
Aiming at the problem that a low-voltage terminal user accompanies power failure during replacement of a box type transformer in the prior art, the invention provides a method for replacing the box type transformer with a low-voltage side completely uninterrupted. The invention is equally applicable to other similar scenarios than transformer replacement, which is exemplified here for simplicity of description.
The technical scheme of the invention is as follows.
A method for replacing a box-type transformer with a low-voltage side completely uninterrupted comprises the following steps:
s01: when the box-type transformer normally supplies power, a low-voltage temporary mobile power supply is arranged nearby the low-voltage cable branch box;
s02: a primary grid-connected low-voltage flexible cable is arranged between the low-voltage temporary mobile power supply and the low-voltage cable branch box;
s03: connecting a low-voltage bus bar in a box-type transformer low-voltage cable branch box with a load side of a temporary mobile power supply grid-connected switch TB by using the laid primary grid-connected flexible cable in a live-line operation mode;
s04, under the condition that the phases (sequences) are consistent, a grid-connected switch TB is switched on, so that the low-voltage cable branch box is powered by the low-voltage temporary mobile power supply and the box-type transformer at the same time, and one-time grid connection is successful;
s05: carrying out load transfer and switching power supplies, namely disconnecting a wire inlet switch of a low-voltage cable branch box from a box-type transformer after the output current of the low-voltage temporary power supply reaches a preset value, and switching the power supply of the low-voltage cable branch box from the box-type transformer to the power supply of the low-voltage temporary mobile power supply;
s06: sequentially disconnecting a low-voltage main switch and a high-voltage switch of the box-type transformer, and replacing the box-type sample transformer in a power failure maintenance mode;
s07: after the box-type transformer is subjected to power failure maintenance and replacement, a high-voltage switch and a low-voltage main switch of the box-type transformer are closed, and a secondary grid-connected low-voltage flexible cable is arranged between a low-voltage temporary mobile power supply and a low-voltage cable branch box;
s08: connecting the power supply side of an incoming line switch in a box-type transformer low-voltage cable branch box with the MB load side of a temporary mobile power supply commercial power access switch by using the laid secondary grid-connected flexible cable in a live-line operation mode;
s09: under the condition that the phases (sequences) are consistent, a commercial power access switch MB of the temporary mobile power supply is switched on, the low-voltage temporary mobile power supply and the box-type transformer are connected in parallel at the moment, the secondary grid-connection operation is completed, and the load transfer to the box-type transformer is automatically started; when the load transfer reaches a preset range, the grid-connected switch TB automatically opens, at the moment, the low-voltage temporary mobile power supply exits, and the low-voltage cable branch box supplies power to a circuit consisting of a box-type transformer through a special connecting device, a secondary grid-connected cable, a mains supply access switch MB, a primary grid-connected cable and a converging clamp;
s10: under the condition that the phases (sequences) are consistent, the incoming line switch of the low-voltage cable branch box is switched on, at the moment, one side of the low-voltage cable branch box supplies power through the box-type transformer and the incoming line switch in the low-voltage cable branch box, and the other side of the low-voltage cable branch box also supplies power to the low-voltage cable branch box through a bypass circuit consisting of a special connecting device, a secondary grid-connected low-voltage flexible cable, a commercial power access switch MB, the low-voltage flexible cable 1 and a confluence clamp;
s11: and respectively disconnecting the commercial power access switch MB and the mobile power supply outgoing line switch GB, and stopping the low-voltage temporary mobile power supply step by step and quitting the operation site.
According to the invention, the low-voltage cable branch box and the medium-low voltage terminal users on the box type transformer power supply link are powered by using the low-voltage temporary mobile power supply in a two-time grid-connection mode during the replacement period of the box type transformer, and the low-voltage cable branch box and the medium-low voltage terminal users are switched back to the box type transformer for power supply in a hot-down mode after the box type transformer is replaced, so that the whole process is completely uninterrupted, and compared with the normal power failure for replacing the box type transformer, the low-voltage terminal users are completely accompanied and stopped until the box type transformer is replaced, so that the loss of the number of users during the low-voltage accompanying power failure is greatly reduced, and the reliability of low-voltage power supply and the power operator environment are effectively improved.
Preferably, the step of electrically connecting the box-type transformer low-voltage cable branch box to a single side of the temporary mobile power grid-connected switch TB includes: confirming that the low-voltage temporary mobile power supply grid-connected switch TB and the commercial power access switch MB are both in a brake-off state, adopting a live working mode, under the condition that a low-voltage busbar in a low-voltage cable branch box is electrified, connecting the low-voltage cable branch box busbar with a load socket of the grid-connected switch TB on the temporary mobile power supply through a low-voltage flexible cable by using a busbar clamp.
Preferably, the method for supplying power to the low-voltage cable branch box from the low-voltage temporary mobile power supply and the box-type transformer simultaneously by switching on the grid-connected switch TB when the phases (sequences) are consistent includes: and starting the low-voltage temporary mobile power supply, closing a temporary mobile power supply outlet switch GB, transmitting power to a low-voltage temporary mobile power supply busbar, performing synchronous detection after the cores on two sides of a grid-connected switch TB are consistent, and adjusting the voltage difference, the frequency and the phase angle difference of the low-voltage temporary mobile power supply and the busbar of the low-voltage cable branch box of the box-type transformer until the grid-connected requirement is met. And after the grid-connected switch TB is closed, one-time grid connection is successful, and low-voltage load transfer is carried out.
Preferably, the box-type transformer repair and replacement includes: after the output load of the low-voltage temporary mobile power supply reaches a preset value, namely the low-voltage load is transferred completely, a line inlet switch of the low-voltage cable branch box is disconnected, the power supply of the low-voltage cable branch box is switched to be supplied with power by the low-voltage temporary mobile power supply independently, a low-voltage main switch and a high-voltage switch of the box-type transformer are sequentially disconnected, relevant safety measures are made to carry out power failure maintenance and replacement on the box-type transformer, after the power failure maintenance and replacement of the box-type transformer are completed, the relevant safety measures are removed, the high-voltage switch, the low-voltage main switch and the low-voltage line outlet switch of the box-type transformer are sequentially closed, power is transmitted to the power supply side of the line inlet switch of the low-voltage cable branch box, the load side of the line inlet switch of the low-voltage cable branch box supplies power to the low-voltage temporary mobile power supply, and the power supply side supplies power to the box-type transformer.
Preferably, the secondary grid connection preparation includes: laying a secondary grid-connected low-voltage flexible cable between the low-voltage temporary mobile power supply and the low-voltage cable branch box; confirming that the commercial power access switch MB is in an opening state, opening the quick interface locking device at the commercial power side of the plugboard, adopting a live working mode, and connecting the power supply side of the incoming line switch in the low-voltage cable branch box of the box-type transformer with the load side of the commercial power access switch MB of the temporary mobile power supply by using a secondary grid-connected low-voltage flexible cable through a special connecting device and a quick interface.
Preferably, the secondary grid-connection operation includes: after the phases (sequences) are detected to be consistent, the commercial power access switch MB is switched on, the load is transferred to the box-type transformer, the secondary grid-connection operation is completed, when the load transfer reaches a preset range, namely the output current of the box-type transformer reaches a preset value, the grid-connection switch TB automatically opens, at the moment, the low-voltage temporary power supply quits to supply power to the low-voltage cable branch box, and the low-voltage cable branch box is completely supplied with power by the box-type transformer.
Preferably, the step-by-step shutdown of the low-voltage temporary mobile power supply and exit from the operation site includes: after the phases on the two sides of the incoming line switch of the low-voltage cable branch box are checked to be correct, the incoming line switch of the low-voltage cable branch box is switched on, one side of the low-voltage cable branch box supplies power through a box-type transformer and the incoming line switch in the low-voltage cable branch box, and the other side of the low-voltage cable branch box supplies power to the low-voltage cable branch box through a bypass circuit consisting of a special connecting device, a secondary grid-connected low-voltage flexible cable, a mains supply access switch MB, a primary grid-connected low-voltage flexible cable and a confluence clamp; and sequentially disconnecting the commercial power access switch MB and the low-voltage temporary mobile power supply outgoing line switch GB, and finally stopping the low-voltage temporary mobile power supply and quitting the operation site.
Preferably, when the load of the low-voltage cable branch box is large and a single low-voltage temporary mobile power supply cannot completely meet the power supply requirement, a plurality of low-voltage temporary mobile power supplies are connected in series at a pre-stage unit of the low-voltage temporary mobile power supply to increase the output capacity and meet the power consumption requirement of a low-voltage cable branch box terminal user.
Preferably, when a plurality of low-voltage cable branch boxes are arranged on the low-voltage side of one box-type transformer, a plurality of low-voltage temporary mobile power supplies are arranged in a distributed mode, a primary grid-connected low-voltage flexible cable and a secondary grid-connected low-voltage flexible cable are used respectively to electrically connect the low-voltage temporary mobile power supplies and the low-voltage cable branch boxes, and then a primary grid-connected step and a secondary grid-connected step are executed to switch power supplies of the low-voltage cable branch boxes.
The substantial effects of the invention include: during the replacement of the box-type transformer, the low-voltage cable branch box on the power supply link of the box-type transformer and the medium-low voltage terminal users thereof are powered by adopting a mode of connecting the low-voltage temporary mobile power supply with the power for two times, and then the low-voltage cable branch box is switched back to the box-type transformer to supply power by adopting a hot-falling mode, the whole process is completely uninterrupted, compared with the normal power failure, the box-type transformer is replaced for at least several hours, the low-voltage terminal users are completely accompanied and stopped until the box-type transformer is completely replaced, the loss of the number of users during the low-voltage accompanying power failure is greatly reduced, and the reliability of low-voltage power supply and the power operator environment are effectively improved. Brings great economic benefit and social benefit for enterprises.
Drawings
FIG. 1 is a schematic diagram of a conventional box transformer and low voltage cable breakout box wiring;
FIG. 2 is a wiring diagram of double grid connection in an embodiment of the invention;
FIG. 3 is a schematic wiring diagram before primary grid connection in the embodiment of the invention;
FIG. 4 is a schematic wiring diagram of the box-type transformer before power failure and replacement after primary grid connection in the embodiment of the invention;
FIG. 5 is a schematic wiring diagram before secondary grid connection in the embodiment of the invention;
FIG. 6 is a schematic diagram of wiring after secondary grid connection in the embodiment of the invention;
fig. 7 is a schematic wiring diagram of the low-voltage temporary mobile power supply after being completely withdrawn in the embodiment of the invention.
Detailed Description
The technical solution of the present application will be described with reference to the following examples. In addition, numerous specific details are set forth below in order to provide a better understanding of the present invention. It will be understood by those skilled in the art that the present invention may be practiced without some of these specific details. In some instances, methods, means, elements and circuits that are well known to those skilled in the art have not been described in detail so as not to obscure the present invention.
Example (b):
as shown in fig. 2 to 7, the wiring schematic diagram in different processes of the method for replacing the box-type transformer with the low-voltage side completely without power failure specifically includes the following steps:
1. as shown in fig. 3: due to the needs of equipment operation and maintenance or municipal construction, the box-type transformer in the drawing needs to be replaced (overhauled and transferred), and at the moment, a mode of connecting a low-voltage temporary mobile power supply in a grid-connected mode twice is adopted to ensure that power is continuously supplied to a low-voltage terminal user connected out of a low-voltage cable branch box during the replacement (overhauling and transfer) of the box-type transformer. The box-type transformer has a plurality of low-voltage outgoing lines, and a plurality of low-voltage cable branch boxes are correspondingly arranged, and one of the low-voltage cable branch boxes is taken as an example in fig. 3 for description.
2. As shown in fig. 3: the low-voltage temporary mobile power supply is provided with an AC-220V single-phase output and a load/pre-stage unit interface which can be connected with a plurality of low-voltage temporary mobile power supplies in series. And confirming that the outlet switch GB, the grid-connected switch TB and the mains supply access switch MB are all in the off position. The incoming line switch JK1 of the low-voltage cable branch box 1 is in a switch-on position, and the outgoing line switches YK1 and YK2 of the low-voltage terminal user are in a switch-on state. The low voltage cable branch box 1 is now powered by a box transformer.
3. As shown in fig. 3, a low-voltage flexible cable 1 is laid between the low-voltage temporary mobile power supply and the low-voltage cable branch box 1, the low-voltage flexible cable 1 is laid on a damp-proof canvas or an insulating pad, and when a plurality of low-voltage flexible cables are connected and continuously used, a special quick connection joint is used and a joint box is used for protection. Meanwhile, when crossing a crossing where vehicles pass, the flexible cable is arranged in the cable cover plate to prevent the vehicles passing through from being crushed.
4. As shown in fig. 3, when the low-voltage temporary mobile power supply grid-connected switch TB load socket is tested to be charged and no voltage is determined, one end of the low-voltage flexible cable 1 is connected with the low-voltage temporary mobile power supply load socket through the quick interface. At low-voltage cable feeder pillar 1 side, concatenate low-voltage flexible cable 1 with the clamp that converges, test electricity on the female row of low-voltage cable feeder pillar 1 and confirm that there is the electricity, test electricity on the clamp that converges and confirm after there is no voltage, adopt live working mode will be connected with the clamp that converges of low-voltage flexible cable 1 and fix on the female row of low-voltage cable feeder pillar 1 low-voltage. At the moment, the load side of the low-voltage temporary mobile power grid-connected switch TB supplies power to the box-type transformer power supply.
5. The low-voltage temporary mobile power supply is started, after the condition that the starting is normal is confirmed, the outlet switch GB is switched on to transmit power to the low-voltage temporary mobile power supply busbar, the power supply side of the grid-connected switch TB supplies power to the low-voltage temporary mobile power supply, the load side supplies power to the box-type transformer, whether the phases (sequences) of the power supply side and the load side of the grid-connected switch TB are consistent needs to be detected, and if the phases (sequences) of the power supply side and the load side of the grid-connected switch TB are not consistent, the overlapping positions of the converging clamps A, C on the low-voltage busbar side of the low-voltage cable branch box are exchanged until the phases (sequences) are detected to be consistent.
6. And pressing the grid-connected switch TB, starting synchronous detection by a grid-connected module in the low-voltage temporary mobile power supply grid-connected switch TB, automatically adjusting the voltage difference, the frequency and the phase angle difference between the low-voltage temporary mobile power supply and the busbar of the low-voltage cable branch box of the box-type transformer, and then automatically closing the grid-connected switch TB. At the moment, the low-voltage cable branch box 1 is simultaneously powered by the box-type transformer and the low-voltage temporary mobile power supply.
7. When the grid-connected switch TB is switched on, although the utility power access switch MB is still in the off position, for safety reasons: the commercial power socket side, namely the load side of the commercial power access switch MB, automatically starts the quick socket locking device, and prevents the flexible cable from being inserted without confirming the switch state of the MB in the operation process.
8. When the load transfer reaches a preset range, namely the output current of the low-voltage temporary power supply reaches a preset value, according to an instruction of a field work responsible person, a worker disconnects a wire inlet switch JK1 in the low-voltage cable branch box 1, at the moment, the low-voltage cable branch box 1 and low-voltage end users 1 and 2 in the low-voltage cable branch box are powered by the low-voltage temporary mobile power supply, and one-time grid connection operation is completed.
9. The low-voltage main switch DK and the high-voltage switch GK of the box-type transformer and all the low-voltage outlet switches (comprising CK1) are sequentially disconnected as shown in FIG. 4. After safety measures are taken, a power failure maintenance mode is adopted to replace (maintain and move) the box type transformer.
10. After the box-type transformer is replaced (repaired and moved), after corresponding safety measures are removed, the high-voltage switch GK, the low-voltage main switch DK and the low-voltage outlet switch CK1 are sequentially switched on, and the outlet wire at the low-voltage side of the box-type transformer supplies power to the inlet wire power side of an inlet wire switch JK1 of the low-voltage cable branch box 1. At the moment, the incoming line power side of an incoming line switch JK1 of the low-voltage cable branch box 1 is powered by the box-type transformer, and the outgoing line load side of the incoming line switch JK1 is powered by the low-voltage temporary mobile power supply.
11. Lay between interim portable power source of low pressure and the low voltage cable feeder pillar and set up low pressure flexible cable 2, low pressure flexible cable 2 should lay on damp-proof canvas or insulating pad, and when many low pressure flexible cable connection continue to use, use special quick connect to connect and use the splice box to protect. Meanwhile, when crossing a crossing where vehicles pass, the flexible cable is arranged in the cable cover plate to prevent the passing vehicles from being crushed.
12. Confirming that the commercial power access switch MB is in an opening state, manually operating to open a locking device of a commercial power socket side quick interface, checking electricity, and after confirming that no voltage exists, connecting one end of the low-voltage flexible cable 2 with a low-voltage temporary mobile power supply through a quick interface on the commercial power socket.
13. A live working mode is adopted under the condition that the power supply side of the incoming line switch JK1 in the low-voltage cable branch box 1 is electrified, and a special connecting device is installed. As shown in fig. 5.
14. And then the other end of the low-voltage flexible cable 2 is tested, after the fact that no voltage exists is verified, the other end of the low-voltage flexible cable 2 is connected with a special connecting device, and finally the power side of an incoming line switch JK1 of the low-voltage cable branch box 1 is connected with a mains supply socket at a mains supply access switch MB on the temporary mobile power supply through the low-voltage flexible cable 2 and the special connecting device. Namely, the commercial power of the low-voltage temporary mobile power supply is connected to the MB power supply side of the switch to supply power to the low-voltage temporary mobile power supply, and the box-type transformer is supplied power to the load side. As shown in fig. 5.
15. The phases (sequences) of both sides of the mains supply access switch MB are checked respectively. If the phases (sequences) are not consistent, the low-voltage outgoing switch CK1 of the box-type transformer is disconnected, and the load side A, C phase connection of the outgoing switch CK1 is adjusted until the phase (sequence) detection is consistent.
16. After phases (sequences) on two sides of a commercial power access switch MB are checked to be consistent, secondary grid connection of a low-voltage temporary mobile power supply is prepared, the low-voltage temporary mobile power supply commercial power access switch MB is pressed, at the moment, the automatic starting synchronous detection function in the low-voltage temporary mobile power supply commercial power access switch MB automatically adjusts the voltage difference, the frequency and the phase angle difference of the power side of the low-voltage temporary mobile power supply and a power inlet switch JK1 of a low-voltage cable branch box 1 of a box type transformer to meet grid connection requirements, the commercial power access switch MB is automatically switched on, the low-voltage temporary mobile power supply and the box type transformer are in grid connection operation, loads are automatically transferred to the box type transformer, and secondary grid connection operation is completed;
17. when the load transfer reaches a preset range, namely after the output current of the box-type transformer reaches a preset value, the low-voltage temporary mobile power supply automatically disconnects the grid-connected switch TB, at the moment, the low-voltage temporary mobile power supply quits, and the low-voltage cable branch box 1 is powered by the box-type transformer. At this time, the low-voltage cable branch box 1 supplies power to the low-voltage cable branch box 1 only through a circuit formed by the special connecting device, the low-voltage flexible cable 2, the commercial power access switch MB, the low-voltage flexible cable 1 and the bus clamp, as shown in fig. 6;
18. and (4) checking the phases of the power side and the load side-two sides of the incoming line switch JK1 of the low-voltage cable branch box 1 and then switching on.
19. The commercial power access switch MB is pressed to be opened, the commercial power access switch MB is opened, the low-voltage temporary mobile power supply completely exits at the moment, and the low-voltage cable branch box 1 is supplied with power by a low-voltage cable branch box inlet cable of the box-type transformer. In the above process, the low-voltage end users 1, 2 are supplied with power completely without interruption.
20. Disconnecting a low-voltage temporary mobile power supply outgoing line switch GB; and then the unit in the low-voltage temporary mobile power supply is shut down (at the moment, the unit can be shut down according to a cooling operation and shut down mode, and the unit can also be shut down by skipping emergency braking in a cooling operation stage).
21. And (3) removing the confluence clamp on the low-voltage busbar in the low-voltage cable branch box 1 and the low-voltage flexible cable 1 along with the confluence clamp in a live working mode, and removing the special connecting device at one end of the power supply side of the incoming line switch JK1 in the low-voltage cable branch box 1 and the low-voltage flexible cable 2 in the live working mode, as shown in fig. 7. And finally, the low-voltage flexible cables 1 and 2, the confluence clamp, the special connecting device and the like are stored in a tool box.
22. When the load of the low-voltage cable branch box is large, and a single low-voltage temporary mobile power supply cannot completely meet the power supply requirement, a plurality of low-voltage temporary mobile power supplies can be connected in series at a pre-stage unit of the low-voltage temporary mobile power supply to increase the output capacity.
23. When a plurality of low-voltage cable branch boxes are arranged on the low-voltage side of one box-type transformer, a plurality of low-voltage temporary mobile power supplies can be arranged in a distributed mode, and then the power supply switching is carried out in the mode of completely not stopping power in sequence.
24. And the low-voltage temporary mobile power supply is electrically connected with the low-voltage cable branch box by using a quick connection mode consisting of a low-voltage flexible cable, a confluence clamp and a special connecting device.
25. The low-voltage flexible cable is connected with the low-voltage temporary mobile power supply in a form of a quick plugging interface, so that the connection speed is further increased, and the connection efficiency is improved.
In the embodiment, the temporary low-voltage mobile power supply uses a Huadong power HDV150 type power generation vehicle, the power generation unit adopts a Stamford power generation unit, the rated voltage is 0.4kV, the rated power is 150kVA/120kW, the rated output current is 217A, the power factor is 0.8 (hysteresis), and the temporary low-voltage mobile power supply can fully run for 8 hours under the condition of full oil.
The confluence clamp comprises: SFE company, france, strong locking insulated bus clamps with quick connect single sockets. The maximum voltage of the clamp is 1000V, the maximum current is 400A, the clamp is suitable for connection on a busbar, and the clamp is provided with a contact protection insulating handle.
The flexible cable is: french SFE company, 120mm2 low-voltage insulation drainage cable, working voltage is 1000V, maximum current is 400A, cable weight: 1460g/m, quick male connectors are preassembled at the two ends of the cable, and a connector protective cover is arranged to prevent dust and impurities from entering.
The special connecting device is provided for Zhejiang Daitan commercial live working branch companies.
In the period of replacing the box-type transformer, the low-voltage cable branch box on the power supply link of the box-type transformer and the medium-low voltage terminal users are powered by adopting a mode of connecting the low-voltage temporary mobile power supply to the power supply link twice, the box-type transformer is switched back to be powered by adopting a hot-falling mode, the whole process is completely uninterrupted, compared with the normal power failure, the box-type transformer is replaced for at least several hours, all low-voltage terminal users accompany and stop until the box-type transformer is replaced, the loss of the number of users during the low-voltage accompanying and power failure is greatly reduced, and the reliability of low-voltage power supply and the environment of power operators are effectively improved. Brings great economic benefit and social benefit for enterprises.
From the above description of the embodiments, those skilled in the art will appreciate that the above description is only a specific embodiment of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily conceive of changes or substitutions within the technical scope of the present disclosure, and all such changes or substitutions are intended to be included within the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.
Claims (9)
1. A method for replacing a box-type transformer with a low-voltage side completely uninterrupted is characterized by comprising the following steps:
s01: when the box-type transformer normally supplies power, a low-voltage temporary mobile power supply is arranged nearby the low-voltage cable branch box;
s02: a low-voltage flexible cable is arranged between the low-voltage temporary mobile power supply and the low-voltage cable branch box;
s03: connecting a low-voltage bus bar in a box-type transformer low-voltage cable branch box with a load side of a temporary mobile power supply grid-connected switch TB by using the laid primary grid-connected flexible cable in a live-line operation mode;
s04: under the condition that the phases (sequences) are consistent, a grid-connected switch TB is switched on, so that the low-voltage cable branch box is powered by the low-voltage temporary mobile power supply and the box-type transformer at the same time, and one-time grid connection is successful;
s05: carrying out load transfer and switching power supplies, namely disconnecting a wire inlet switch from the box-type transformer in the low-voltage cable branch box after the output current of the low-voltage temporary power supply reaches a preset value, and switching the power supply of the low-voltage cable branch box from the power supply of the box-type transformer to the power supply of the low-voltage temporary mobile power supply;
s06: sequentially disconnecting a low-voltage main switch and a high-voltage switch of the box-type transformer, and replacing the box-type sample transformer in a power failure maintenance mode;
s07: after the box-type transformer is subjected to power failure maintenance and replacement, a high-voltage switch and a low-voltage main switch of the box-type transformer are closed, and a secondary grid-connected low-voltage flexible cable is arranged between a low-voltage temporary mobile power supply and a low-voltage cable branch box; s08: connecting the power supply side of an incoming line switch in a box-type transformer low-voltage cable branch box with the MB load side of a temporary mobile power supply commercial power access switch by using the laid secondary grid-connected flexible cable in a live-line operation mode;
s09: under the condition that the phases (sequences) are consistent, a commercial power access switch MB of the temporary mobile power supply is switched on, the low-voltage temporary mobile power supply and the box-type transformer are connected in parallel at the moment, the secondary grid-connection operation is completed, and the load transfer to the box-type transformer is automatically started; when the load transfer reaches a preset range, the grid-connected switch TB automatically opens, at the moment, the low-voltage temporary power supply exits, and the low-voltage cable branch box supplies power to a circuit consisting of a secondary grid-connected cable, a commercial power access switch MB and a primary grid-connected cable through a box-type transformer;
s10: under the condition that the phases (sequences) are consistent, the incoming line switch of the low-voltage cable branch box is switched on, at the moment, one side of the low-voltage cable branch box supplies power through the box-type transformer and the incoming line switch in the low-voltage cable branch box, and the other side of the low-voltage cable branch box also supplies power to the low-voltage cable branch box through a bypass consisting of a secondary grid-connected low-voltage flexible cable, a commercial power access switch MB and the low-voltage flexible cable;
s11: and respectively disconnecting the commercial power access switch MB and the mobile power supply outgoing line switch GB, and stopping the low-voltage temporary mobile power supply step by step and quitting the operation site.
2. The method for replacing a box-type transformer with a complete uninterrupted low-voltage side as claimed in claim 1, wherein the step S03 comprises: confirming that the low-voltage temporary mobile power supply grid-connected switch TB and the commercial power access switch MB are both in a brake-off state, adopting a live working mode, under the condition that a low-voltage busbar in a low-voltage cable branch box is electrified, connecting the low-voltage cable branch box busbar with a load socket of the grid-connected switch TB on the temporary mobile power supply through a low-voltage flexible cable by using a busbar clamp.
3. The method for replacing a box-type transformer with a complete uninterrupted low-voltage side as claimed in claim 2, wherein step S04 comprises: starting a low-voltage temporary mobile power supply, closing a temporary mobile power supply outlet switch GB, transmitting power to a low-voltage temporary mobile power supply busbar, checking the cores on the two sides of a grid-connected switch TB to be consistent, performing synchronous detection, adjusting the voltage difference, the frequency and the phase angle difference of the low-voltage temporary mobile power supply and the busbar side of a low-voltage cable branch box of a box-type transformer until the grid-connected requirement is met, closing the grid-connected switch TB, successfully connecting the grid at one time, and performing low-voltage load transfer.
4. The method for replacing a box-type transformer with a complete uninterrupted low-voltage side as claimed in claim 3, wherein step S05 comprises: and after the output current of the low-voltage temporary power supply reaches a preset value, disconnecting a wire inlet switch from the box type transformer in the low-voltage cable branch box, and switching the low-voltage load, namely switching the power supply of the low-voltage cable branch box from the box type transformer to the power supply of the low-voltage temporary mobile power supply.
5. The method for replacing a box-type transformer with a complete uninterrupted low-voltage side as claimed in claim 4, wherein step S06 comprises: the method comprises the steps of sequentially disconnecting a low-voltage main switch and a high-voltage switch of the box type transformer, carrying out maintenance and replacement of the box type transformer by making relevant safety measures, removing the relevant safety measures after the box type transformer is completely replaced due to power failure, sequentially switching on the high-voltage switch, the low-voltage main switch and a low-voltage outgoing switch of the box type transformer, transmitting power to a power supply side of a low-voltage cable branch box incoming switch, supplying power to a low-voltage temporary mobile power supply on the load side of the low-voltage cable branch box incoming switch at the moment, and supplying power to the box type transformer on the power supply side.
6. The method for replacing the box-type transformer with the low-voltage side completely uninterrupted according to claim 1, wherein before secondary grid connection, a low-voltage flexible cable is laid between a low-voltage temporary mobile power supply and a low-voltage cable branch box; confirming that the commercial power access switch MB is in an opening state, opening the quick interface locking device at the commercial power side of the plugboard, adopting a live working mode, and connecting the power supply side of the incoming line switch in the low-voltage cable branch box of the box-type transformer with the load side of the commercial power access switch MB of the temporary mobile power supply by using a secondary grid-connected low-voltage flexible cable through a special connecting device and a quick interface.
7. The method for replacing the box-type transformer with the low-voltage side completely uninterrupted according to claim 6, wherein the secondary grid-connection operation comprises the following steps: after the phases (sequences) are detected to be consistent, the commercial power access switch MB is switched on, the load is transferred to the box-type transformer, the secondary grid-connection operation is completed, when the load transfer reaches a preset range, namely the output current of the box-type transformer reaches a preset value, the grid-connection switch TB automatically opens, at the moment, the low-voltage temporary power supply quits to supply power to the low-voltage cable branch box, and the low-voltage cable branch box is completely supplied with power by the box-type transformer.
8. The method for replacing the box-type transformer with the low-voltage side completely uninterrupted according to claim 7, wherein the step-by-step shutdown of the low-voltage temporary mobile power supply and the step-by-step exit from the operation site comprise the following steps: after the phases on the two sides of the incoming line switch of the low-voltage cable branch box are checked to be correct, the incoming line switch of the low-voltage cable branch box is switched on, at the moment, one side of the low-voltage cable branch box supplies power through a box-type transformer and the incoming line switch in the low-voltage cable branch box, and the other side of the low-voltage cable branch box supplies power to the low-voltage cable branch box through a bypass formed by a special connecting device, a secondary grid-connected low-voltage flexible cable, a commercial power access switch MB, a primary grid-connected low-voltage flexible cable and a confluence clamp; at the moment, the commercial power access switch MB and the low-voltage temporary mobile power supply outgoing line switch GB can be sequentially disconnected, and finally the low-voltage temporary mobile power supply is stopped and exits from the operation site.
9. The method for replacing a box-type transformer with complete uninterrupted low-voltage side according to claim 1 or 2,
when the load of the low-voltage cable branch box is large and a single low-voltage temporary mobile power supply cannot completely meet the power supply requirement, a plurality of low-voltage temporary mobile power supplies are connected in series at a pre-stage unit of the low-voltage temporary mobile power supply to increase the output capacity and meet the power consumption requirement of a terminal user of the low-voltage cable branch box; when a plurality of low-voltage cable branch boxes are arranged on the low-voltage side of one box-type transformer, a plurality of low-voltage temporary mobile power supplies are arranged in a distributed mode, and then power supply switching is respectively carried out.
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