Temporary access box on application rod and access method thereof

Abstract

The invention discloses a temporary access box on an application pole and an access method thereof. The access box comprises a box body, and a disconnecting link respectively connected with a mobile power supply vehicle and a low-voltage overhead line is arranged in the box body; the disconnecting link at the rear end is connected with a circuit breaker, and the circuit breaker is provided with a cable terminal. The pile head of the disconnecting link located at the front end is provided with an intelligent fusion terminal used for collecting and uploading electric quantity and power generation and protection time information. Compared with the conventional operation mode of accessing a transformer body and a busbar, the method for carrying out transformer power protection operation by applying the temporary access box of the power generation car on the pole has the remarkable advantages of high safety, high scene adaptability, high economical efficiency and simplicity in operation through practical application verification.

Description

Technical Field

[0001] The present invention relates to an application pole-mounted temporary access box and an access method thereof, belonging to the technical field of power protection and power supply, and particularly to the technical field of low-voltage power protection and power supply. Background Art

[0002] With the development of the economic society, the requirements of power users for power supply reliability are increasing day by day, and the maintenance mode of the distribution network is gradually transforming to the mode of live working. After years of development, live working in medium voltage has basically realized the implementation of maintenance tasks such as replacement of pole-mounted switch equipment, insulators, and poles without power interruption. However, for distribution network maintenance operations with large workloads and operation scopes such as wire replacement, as well as maintenance operations that require replacement and overhaul of relevant equipment such as the transformer itself and the metering cabinet, the relevant transformers to be connected are often still powered off, and the power-off time for such operations is often relatively long, which has a great impact on relevant low-voltage users.

[0003] Distribution network maintenance personnel use a mobile power vehicle (hereinafter referred to as a power generation vehicle) to first supply power to low-voltage users of the transformer, and then carry out maintenance of the upper-level power grid or replacement of old transformers, effectively shortening the overall power-off time of low-voltage users. However, the traditional method of power-off connection to the low-voltage busbar of the transformer or metering cabinet will cause power-off for about half an hour twice, and there is a relatively high risk of frequent power-off.

[0004] In the past two years, with the application of quasi-synchronous grid connection technology in power generation vehicles, the existing power generation vehicles in Shaoxing area have also started to be transformed with quasi-synchronous devices. In theory, the use of quasi-synchronous technology can achieve power-on and power-off of the power generation vehicle to and from low-voltage users without power interruption. However, there are still the following problems in the actual use of power generation vehicles by the operation team: One is that the operation items are highly restricted. The second is that the operation risks are relatively high. The third is that it is easy to cause frequent power-off complaints. The fourth is that the requirements for the operation site are relatively high. The fifth is that it has a great impact on the line loss of the transformer substation area. The sixth is that the prices of equipment and components are high.

[0005] Therefore, shortening the power-off time caused by the switching between the mains power supply and the power supply of the mobile power vehicle for low-voltage users of the transformer substation, or even achieving power-off-free switching, is the main pursuit of current power operations. Summary of the Invention

[0006] The purpose of the present invention is to provide an application pole-mounted temporary access box with a wide range of applications, low risks, low requirements for the site, low impact, and low equipment prices.

[0007] The above technical purpose of the present invention is achieved through the following technical solutions: The access box includes a box body, and a knife switch connected to the mobile power vehicle and the low-voltage overhead line is arranged in the box body; a circuit breaker is connected to the knife switch at the rear end, and a cable terminal is arranged on the circuit breaker; a smart fusion terminal for collecting and uploading power consumption and power protection time information is arranged on the terminal head of the knife switch at the front end.

[0008] Further set as: a hoop is also provided on the box body, and the access box is fixed on the low-voltage line pole by the hoop, and the hoop is 0.8 - 1.2 meters above the ground; Further set as: a low-voltage flexible cable is provided between the mobile power supply vehicle, the access box and the low-voltage overhead line.

[0009] As Figure 1 shown, the present invention also discloses an access method for applying a temporary access box on the pole in the case where both the access and withdrawal of the power generation vehicle adopt the cold transfer method, including the following steps: S1: Reconnoiter the site and install the access box pre-equipped with current transformers and meeting the on-site use conditions at a suitable pole; S2: Disconnect the low-voltage outgoing line switch GK1 and the low-voltage main knife switch related to the maintenance of the substation transformer in sequence; S3: Close the outgoing line switch of the power generation vehicle; S4: Close the knife switch QS1, knife switch QS2, circuit breaker QF1, and QF2 in sequence in the access box; S5: After the maintenance of the related substation transformer is completed, after removing the corresponding safety measures, open the circuit breaker QF1, QF2, knife switch QS2, knife switch QS1, and the outgoing line switch of the power generation vehicle in sequence, and close the low-voltage main knife switch and the low-voltage outgoing line switch GK1 in sequence; S6: Remove the low-voltage flexible cable on the load side of the access box live and store two sets of low-voltage flexible cables.

[0010] As Figure 2 , the present invention also discloses an access method for applying a temporary access box on the pole in the case where the access of the power generation vehicle adopts quasi-synchronization and the power generation vehicle withdraws from service, including the following steps: S1: Reconnoiter the site and install the access box pre-equipped with current transformers and meeting the on-site use conditions at a suitable pole; S2: Close the outgoing line switch of the power generation vehicle; S3: Close the knife switch QS1, knife switch QS2, circuit breaker QF1, and QF2 in sequence in the access box; S4: Disconnect the low-voltage outgoing line switch GK1 and the low-voltage main knife switch related to the maintenance of the substation transformer; S5: After the maintenance of the related substation transformer is completed, after removing the corresponding safety measures, open the circuit breaker QF1, QF2, knife switch QS2, knife switch QS1, and the outgoing line switch of the power generation vehicle in sequence, and close the low-voltage main knife switch and the low-voltage outgoing line switch GK1 in sequence; S6: Remove the low-voltage flexible cable on the load side of the access box live and store two sets of low-voltage flexible cables.

[0011] As Figure 3 , the present invention also discloses an access method for applying a temporary access box on the pole in the case where both the access and withdrawal of the power generation vehicle adopt synchronization, including the following steps: S1: Conduct a site survey, and install the access box pre-equipped with current transformers and meeting the on-site usage conditions at a suitable pole. S2: Check that the outgoing line switch GB, grid connection switch TB, and mains power access switch MB of the low-voltage power generation vehicle are all in the off position; currently, the low-voltage overhead line 1 is powered by the involved maintenance substation; lay the low-voltage flexible cable 1 between the low-voltage temporary mobile power supply and the temporary access box on the pole. S3: Adopt live working methods to lay the low-voltage flexible cable 2 between the temporary access box on the pole and the low-voltage overhead line 1; after confirming that the line connection is stable, start the low-voltage temporary mobile power supply and close the outgoing line switch GB. At this time, the power supply side of the grid connection switch TB is powered by the low-voltage temporary mobile power supply, and the load side is powered by the involved maintenance substation. S4: Detect whether the phases (sequences) of the power supply side and the load side of the grid connection switch TB are the same. If the two phases (sequences) are not the same, exchange the connection positions of the flexible cables A and C phases on the low-voltage overhead line side until the phase (sequence) detection is the same. S5: Press the grid connection switch TB, and the synchronization device automatically adjusts the voltage difference, frequency, and phase angle difference between the low-voltage temporary mobile power supply and the low-voltage outgoing line side of the involved maintenance substation. After the synchronization detection is passed, the grid connection switch TB is automatically closed; at this time, the low-voltage overhead line 1 is powered by both the involved maintenance substation and the low-voltage temporary mobile power supply. S6: When the output current of the low-voltage temporary power supply reaches the preset value, according to the instructions of the on-site work supervisor, the staff disconnect the low-voltage outgoing line switch GK1 of the low-voltage overhead line 1. At this time, the low-voltage overhead line 1 and its low-voltage end users are powered by the low-voltage temporary mobile power supply, and one-time grid connection operation is completed. S7: Check that the voltage and current sliders of the combined wiring box of the public transformer terminal in the metering cabinet of the involved maintenance substation are indeed in the off position, and remove the public transformer terminal in a live manner; after confirming that the three-phase phase sequence is correct, connect it to the pre-installed current transformer and relocate it to the temporary access box on the pole; at the same time, the staff sequentially disconnect the low-voltage outgoing line switch, high-voltage switch, and low-voltage main switch of the involved maintenance substation. S8: After the maintenance of the involved substation is completed, after removing the corresponding safety measures, sequentially close the low-voltage main switch, high-voltage switch, and low-voltage outgoing line switch. At this time, the low-voltage side outgoing line of the substation supplies power to the power supply side of the incoming line of the low-voltage outgoing line switch GK1 of the low-voltage overhead line 1. At this time, the upper terminal of the low-voltage outgoing line switch GK1 of the low-voltage overhead line 1 is powered by the substation, and the lower terminal is powered by the low-voltage temporary mobile power supply. S9: Lay the low-voltage flexible cable 3 between the low-voltage temporary mobile power supply and the low-voltage cable branch box; check that the mains power access switch MB is in the off state. After verifying that there is no voltage, connect one end of the low-voltage flexible cable 3 to the low-voltage temporary mobile power supply through the quick interface on the mains power socket, and the other end is connected to the upper terminal of the outgoing line switch GK1 by means of live working through a busbar clamp. S10: Check the phases (sequence) on both sides of the mains access switch MB; if the phases (sequence) are inconsistent, disconnect the low-voltage main switch of the substation transformer, and adjust the wiring of phases A and C on the outgoing switch side until the phase (sequence) detection is consistent; S11: Press the grid connection switch TB. The synchronization device automatically adjusts the voltage difference, frequency, and phase angle difference between the low-voltage temporary mobile power supply and the low-voltage outgoing side of the substation transformer under maintenance. After the synchronization detection is passed, the grid connection switch TB is automatically closed; at this time, the low-voltage temporary mobile power supply is operating in parallel with the substation transformer, and automatically starts to transfer the load to the substation transformer, and the secondary grid connection operation is completed; S12: When the load transfer reaches the preset range, that is, when the output current of the substation transformer under maintenance reaches the preset value, the low-voltage temporary mobile power supply automatically disconnects the grid connection switch TB. At this time, the low-voltage temporary mobile power supply exits, and the low-voltage overhead line 1 is powered by the substation transformer; S13: Check the phases on both the power supply side and the load side of the outgoing switch GK1 of the low-voltage overhead line 1. After verification, close the switch; press the off button of the mains access switch MB, and the mains access switch MB is turned off. At this time, the low-voltage temporary mobile power supply completely exits, and the low-voltage overhead line 1 is powered by the incoming cable of the low-voltage cable branch box of the box-type transformer; S14: Remove the public transformer terminal in the temporary access box on the pole and install it in the metering cabinet of the substation transformer at the same location by means of live working. While stopping the internal unit of the low-voltage temporary mobile power supply, remove the two sets of low-voltage flexible cables on the low-voltage overhead line 1 by means of live working and store them in the toolbox.

[0012] In summary, the present invention has the following beneficial effects: Through actual application verification, compared with the conventional operation method of accessing the substation transformer body and busbars, using the temporary access box on the pole for power protection of the substation transformer has the following four significant advantages: First, it has strong safety. It not only tries to avoid overlapping cables, even live overlapping cables, in the narrow metering cabinet, but also uses the existing main protection in the metering cabinet to replace the main isolating switch to achieve load switching. During the operation of the substation transformer, the cabinet door can be kept closed and the low-voltage busbars can be maximally de-energized, greatly improving the safety of line maintenance.

[0013] Second, it has strong scene adaptability. For maintenance situations where it is difficult to perform power protection or quasi-synchronous power protection under conventional conditions such as the power generation vehicle cannot reach, the space of the metering box is limited, and the substation transformer needs to be replaced, this solution can basically solve most problems, and further reduce the power outage time caused by the power supply switching of low-voltage users.

[0014] Third, it has strong economy. The temporary access box on the pole made in this project has a simple structure, and the connectors and components used are all commonly used equipment by front-line employees of power grid enterprises, with low prices, reducing the situation of high prices, complexity and vulnerability of equipment in current low-voltage live working.

[0015] Fourthly, it is easy to operate. The installation method of the box body can refer to the installation method of the box on the marketing pole and can be pre-installed before the maintenance operation day. The components are also common devices. The operation uses the conventional low-voltage work tickets and operation tickets of the distribution network, which is conducive to the rapid promotion by front-line teams.

[0016] To sum up, after the temporary power access box on the pole is put into use, it can greatly reduce the depth and breadth of the application of the power generation vehicle in the distribution network maintenance operation, reduce the risks of various maintenance operations, improve the operation efficiency of the power protection personnel, and has strong promotion value. Brief Description of the Drawings

[0017] Figure 1 It is a wiring schematic diagram in which both the access and withdrawal of the power generation vehicle adopt the cold transfer method; Figure 2 It is a wiring schematic diagram in which the access of the power generation vehicle adopts the quasi-synchronous method; Figure 3 It is a wiring schematic diagram in which both the access and withdrawal of the power generation vehicle adopt the synchronous method; Figure 4 It is a structural schematic diagram of the power generation side of the temporary access box on the pole; Figure 5 It is a structural schematic diagram of the load side of the temporary access box on the pole. Detailed Implementation Modes

[0018] The present invention will be further described in detail below with reference to the accompanying drawings.

[0019] As Figure 4 and Figure 5 shown, for the application of the temporary access box on the pole, the access box includes a box body. Inside the box body, there are disconnect switches respectively connected to the mobile power vehicle (or generator) and the low-voltage overhead line; a circuit breaker is connected to the disconnect switch at the rear end, and a cable terminal is arranged on the circuit breaker; on the terminal of the disconnect switch at the front end, there is an intelligent fusion terminal for collecting and uploading power consumption and power protection time information.

[0020] Among them, this access box does not have the synchronous function. The access methods of quasi-synchronous and secondary synchronous must be used in cooperation with a generator or power generation vehicle with synchronous function. Many currently applied generators or power generation vehicles have synchronous functions, and improving power supply reliability is the current development direction.

[0021] The access box also includes a hoop. The access box is fixed on the low-voltage line pole through the hoop, about one meter above the ground. A low-voltage flexible cable is laid to connect the load side of the access box with the overhead line and the power generation side of the access box with the output end of the power generation vehicle. The power is directly supplied to the low-voltage line through the generator or power generation vehicle, which can expand the operation scope of the power protection operation and facilitate the implementation of the operation process.

[0022] The access method of the temporary access box on the pole in the present invention varies according to specific situations.

[0023] For the first case, where both the connection and disconnection of the power generation vehicle adopt the cold transfer method, it includes the following steps: S1: Reconnoiter the site and install the access box pre-equipped with current transformers and meeting the on-site usage conditions at a suitable pole; S2: Disconnect the low-voltage outgoing line switch GK1 and the low-voltage main knife switch of the involved inspection transformer substation in sequence; S3: Close the outgoing line switch of the power generation vehicle; S4: Close the knife switch QS1, knife switch QS2, circuit breaker QF1, and QF2 in sequence inside the access box; S5: After the inspection of the involved transformer substation is completed and the corresponding safety measures are removed, open the circuit breaker QF1, QF2, knife switch QS2, knife switch QS1, and the outgoing line switch of the power generation vehicle in sequence, and then close the low-voltage main knife switch and the low-voltage outgoing line switch GK1 in sequence; S6: Remove the low-voltage flexible cable on the load side of the access box while energized, and store two sets of low-voltage flexible cables.

[0024] For the second case, when the power generation vehicle is connected using quasi-synchronization and the power generation vehicle is de-energized and disconnected, it includes first closing the knife switch of the overhead access box, and the synchronization device of the power generation vehicle automatically synchronizes and connects to the grid, enabling the non-stop switching from the mains power to the power generation vehicle.

[0025] S1: Reconnoiter the site and install the access box pre-equipped with current transformers and meeting the on-site usage conditions at a suitable pole; S2: Close the outgoing line switch of the power generation vehicle; S3: Close the knife switch QS1, knife switch QS2, circuit breaker QF1, and QF2 in sequence inside the access box; S4: Disconnect the low-voltage outgoing line switch GK1 and the low-voltage main knife switch of the involved inspection transformer substation; S5: After the inspection of the involved transformer substation is completed and the corresponding safety measures are removed, open the circuit breaker QF1, QF2, knife switch QS2, knife switch QS1, and the outgoing line switch of the power generation vehicle in sequence, and then close the low-voltage main knife switch and the low-voltage outgoing line switch GK1 in sequence; S6: Remove the low-voltage flexible cable on the load side of the access box while energized, and store two sets of low-voltage flexible cables.

[0026] For the third case, where both the connection and disconnection of the power generation vehicle adopt synchronization, it includes, during the power generation vehicle disconnection phase, using a busbar clamp to connect the mains side of the power generation vehicle synchronization device to the busbar of the restored operating metering box, operating the synchronization device to build a temporary circuit between the power supply protection line and the mains power, and completing the withdrawal operation of the power supply protection device through the cooperation of the outgoing line switch inside the metering box and the switch inside the overhead access box.

[0027] It includes the following steps: S1: Preparation before power conservation When using the temporary access box on the pole to carry out maintenance work such as replacing the distribution transformer and metering box, and low-voltage outgoing cables, it is necessary to conduct a site survey in advance, and install the access box with pre-installed current transformers that meet the on-site usage conditions at a suitable pole; S2: Power conservation - Connecting the power generation vehicle Check that the outgoing line switch GB, grid connection switch TB, and mains access switch MB of the low-voltage power generation vehicle are all in the off position; currently, the low-voltage overhead line 1 is powered by the distribution transformer involved in the maintenance; lay the low-voltage flexible cable 1 between the low-voltage temporary mobile power supply and the temporary access box on the pole; Lay the low-voltage flexible cable 2 between the temporary access box on the pole and the low-voltage overhead line 1 using live working methods; after confirming that the line connection is stable, start the low-voltage temporary mobile power supply and close the outgoing line switch GB. At this time, the power supply side of the grid connection switch TB is powered by the low-voltage temporary mobile power supply, and the load side is powered by the distribution transformer involved in the maintenance; Detect whether the phases (sequences) of the power supply side and load side of the grid connection switch TB are the same. If the two phases (sequences) are not the same, exchange the connection positions of the flexible cables A and C phases on the low-voltage overhead line side until the phase (sequence) detection is the same; Press the grid connection switch TB, and the synchronization device automatically adjusts the voltage difference, frequency, and phase angle difference between the low-voltage temporary mobile power supply and the low-voltage outgoing line side of the distribution transformer involved in the maintenance. After the synchronization detection is passed, the grid connection switch TB is automatically closed; at this time, the low-voltage overhead line 1 is powered by both the distribution transformer involved in the maintenance and the low-voltage temporary mobile power supply; When the output current of the low-voltage temporary power supply reaches the preset value, according to the instructions of the on-site work supervisor, the staff disconnect the low-voltage outgoing line switch GK1 of the low-voltage overhead line 1. At this time, the low-voltage overhead line 1 and its low-voltage end users are powered by the low-voltage temporary mobile power supply, and the first grid connection operation is completed; Check that the voltage and current sliders of the combined wiring box of the public transformer terminal in the metering cabinet of the distribution transformer involved in the maintenance are indeed in the off position, and remove the public transformer terminal in a live manner. After confirming that the three-phase phase sequence is correct, connect it to the pre-installed current transformer and relocate it to the temporary access box on the pole; at the same time, the staff disconnect the low-voltage outgoing line switch, high-voltage switch, and low-voltage main switch of the distribution transformer involved in the maintenance in sequence; S3: Power conservation - Withdrawing the power generation vehicle After the maintenance of the involved distribution transformer is completed and the corresponding safety measures are removed, close the low-voltage main switch, high-voltage switch, and low-voltage outgoing line switch in sequence. At this time, the low-voltage side outgoing line of the distribution transformer supplies power to the power supply side of the incoming line of the low-voltage outgoing line switch GK1 of the low-voltage overhead line 1. At this time, the upper terminal of the low-voltage outgoing line switch GK1 of the low-voltage overhead line 1 is powered by the distribution transformer, and the lower terminal is powered by the low-voltage temporary mobile power supply; Lay a low-voltage flexible cable 3 between the low-voltage temporary mobile power supply and the low-voltage cable distribution box. Check that the mains access switch MB is in the off state. After verifying that there is no voltage, connect one end of the low-voltage flexible cable 3 to the low-voltage temporary mobile power supply through the quick interface on the mains socket interface, and connect the other end to the upper terminal of the outgoing line switch GK1 by means of live working through a busbar clamp.

[0028] Check the phase (sequence) on both sides of the mains access switch MB; if the phase (sequence) is inconsistent, disconnect the low-voltage main switch of the substation transformer, adjust the wiring of phases A and C on the outgoing line switch side until the phase (sequence) detection is consistent; Press the grid connection switch TB. The synchronization device automatically adjusts the voltage difference, frequency, and phase angle difference between the low-voltage temporary mobile power supply and the low-voltage outgoing line side of the substation transformer under maintenance. After passing the synchronization detection, the grid connection switch TB is automatically closed. At this time, the low-voltage temporary mobile power supply is connected to the grid with the substation transformer and automatically starts to transfer the load to the substation transformer, and the secondary grid connection operation is completed; When the load transfer reaches the preset range, that is, when the output current of the substation transformer under maintenance reaches the preset value, the low-voltage temporary mobile power supply automatically disconnects the grid connection switch TB. At this time, the low-voltage temporary mobile power supply exits, and the low-voltage overhead line 1 is powered by the substation transformer. Check the phase on both the power supply side and the load side of the outgoing line switch GK1 of the low-voltage overhead line 1. After verification, close the switch. Press the off button of the mains access switch MB, and the mains access switch MB is turned off. At this time, the low-voltage temporary mobile power supply completely exits, and the low-voltage overhead line 1 is powered by the incoming cable of the low-voltage cable distribution box of the box-type substation. Remove the temporary access box on the pole inside the public transformer terminal and install it in the metering cabinet of the substation transformer at the same location by means of live working. While shutting down the internal unit of the low-voltage temporary mobile power supply, remove the two sets of low-voltage flexible cables on the low-voltage overhead line 1 by means of live working and store them in the toolbox. In the above process, the temporary access box on the pole is applied to make it not restricted by the construction environment of the substation transformer, reduce the safety risk of maintenance work, ensure the complete uninterrupted power supply of low-voltage terminal users, and realize the metering function throughout the low-voltage power protection process.

[0029] This specific embodiment is only an explanation of the present invention, and it is not a limitation of the present invention. Those skilled in the art can make modifications to this embodiment without creative contributions according to needs after reading this specification, but as long as it is within the scope of the claims of the present invention, it is protected by the patent law.

Claims

1. A temporary access box on the application pole is characterized by: The access box includes a box body, in which are arranged knife switches connected to the mobile power vehicle and the low-voltage overhead lines respectively; the knife switch at the rear end is connected to a circuit breaker, on which a cable terminal is arranged; the pole head of the knife switch at the front end is provided with an intelligent fusion terminal for collecting and uploading power consumption and power generation and protection time information.

2. The temporary access box on the application pole according to claim 1, characterized in that: The box body is also provided with a clamp, which fixes the access box on the low-voltage line tower, and the clamp is 0.8-1.2 meters above the ground.

3. The access method using the temporary access box on the application pole according to claim 2 is characterized in that: A low-voltage flexible cable is arranged between the mobile power supply vehicle, the access box and the low-voltage overhead line.

4. The access method using the temporary access box on the application pole according to claim 1 is characterized in that: In the case where both the connection and exit of the power generation vehicle adopt the cold dump method, the following steps are included: S1: Survey the site and install the access box with pre-installed current transformers and meeting the site conditions at a suitable pole; S2: Disconnect the low-voltage outlet switch GK1 and the low-voltage main switch involved in the maintenance station in sequence; S3: Close the outgoing line switch of the generator car; S4: Close the knife switch QS1, knife switch QS2 and circuit breakers QF1 and QF2 in the access box in sequence; S5: After the maintenance of the transformer is completed and the corresponding safety measures are removed, the circuit breakers QF1, QF2, knife switches QS2, knife switches QS1, and the outgoing line switches of the generator car are opened in sequence, and the low-voltage main knife switch and low-voltage outgoing line switch GK1 are closed in sequence; S6: Remove the low-voltage flexible cable on the load side of the access box while it is energized, and store two sets of low-voltage flexible cables.

5. The access method using the temporary access box on the application pole according to claim 1 is characterized in that: The following steps are included for the case where the generator car is connected using quasi-synchronous mode and the generator car is shut down and exits due to power outage: S1: Survey the site and install the access box with pre-installed current transformers and meeting the site conditions at a suitable pole; S2: Close the outgoing line switch of the generator car; S3: Close the knife switch QS1, knife switch QS2 and circuit breakers QF1 and QF2 in the access box in sequence; S4: Disconnect the low-voltage outlet switch GK1 and the low-voltage main switch of the maintenance station transformer; S5: After the maintenance of the transformer is completed and the corresponding safety measures are removed, the circuit breakers QF1, QF2, knife switches QS2, knife switches QS1, and the outgoing line switches of the generator car are opened in sequence, and the low-voltage main knife switch and low-voltage outgoing line switch GK1 are closed in sequence; S6: Remove the low-voltage flexible cable on the load side of the access box while it is energized, and store two sets of low-voltage flexible cables.

6. The access method using the temporary access box on the application pole as claimed in claim 1 is characterized by: The connection and exit of the power generation vehicle are all synchronized, including the following steps: S1: Survey the site and install the access box with pre-installed current transformers and meeting the site conditions at a suitable pole; S2: Check that the low-voltage generator car outlet switch GB, grid-connected switch TB, and mains access switch MB are all in the disconnected position; the current low-voltage overhead line 1 is powered by the maintenance station transformer involved; lay a low-voltage flexible cable 1 between the low-voltage temporary mobile power supply and the temporary access box on the pole; S3: Use live working to lay low-voltage flexible cable 2 between the temporary access box on the pole and the low-voltage overhead line 1; after confirming that the line connection is stable, start the low-voltage temporary mobile power supply and close the outgoing switch GB. At this time, the power supply side of the grid-connected switch TB is powered by the low-voltage temporary mobile power supply, and the load side is powered by the maintenance platform transformer; S4: Check whether the phase (sequence) of the power supply side and the load side of the grid-connected switch TB is consistent. If the phase (sequence) of the two is inconsistent, the overlapping positions of the A and C phases of the flexible cable on the low-voltage overhead line side are exchanged until the phase (sequence) detection is consistent; S5: Press the grid-connected switch TB, and the synchronization device automatically adjusts the voltage difference, frequency, and phase difference between the low-voltage temporary mobile power supply and the low-voltage outgoing line side of the maintenance platform transformer. After the synchronization detection is passed, the grid-connected switch TB is automatically closed; at this time, the low-voltage overhead line 1 is powered by the maintenance platform transformer and the low-voltage temporary mobile power supply at the same time; S6: When the output current of the low-voltage temporary power supply reaches the preset value, according to the instructions of the on-site work leader, the staff disconnects the low-voltage outlet switch GK1 of the low-voltage overhead line 1. At this time, the low-voltage overhead line 1 and its medium and low-voltage terminal users are powered by the low-voltage temporary mobile power supply, and the one-time grid-connected operation is completed; S7: Check that the voltage and current paddles of the joint junction box of the public transformer terminal in the metering cabinet of the maintenance station are in the disconnected position, and remove the public transformer terminal in a live manner; after confirming that the three-phase sequence is correct, connect it with the pre-installed current transformer and move it to the temporary access box on the pole; at the same time, the staff will disconnect the low-voltage outlet switch, high-voltage switch and low-voltage main switch of the maintenance station transformer in turn; S8: After the maintenance of the transformer is completed, the corresponding safety measures are removed, and the low-voltage main switch, high-voltage switch, and low-voltage outgoing line switch are closed in sequence. At this time, the outgoing line on the low-voltage side of the transformer supplies power to the incoming power supply side 8 of the low-voltage overhead line 1 outgoing line switch GK1. At this time, the upper pile head of the low-voltage overhead line 1 outgoing line switch GK1 is powered by the transformer, and the lower pile head is powered by the low-voltage temporary mobile power supply; S9: Lay low-voltage flexible cable 3 between the low-voltage temporary mobile power supply and the low-voltage cable branch box; check that the mains access switch MB is in the off state. After verifying that there is no voltage, connect one end of the low-voltage flexible cable 3 to the low-voltage temporary mobile power supply through the quick connector on the mains plug interface, and connect the other end to the upper pile head of the outgoing switch GK1 through the busbar clamp in a live working mode; S10: Check the phase (sequence) on both sides of the mains access switch MB; if the phase (sequence) is inconsistent, disconnect the transformer low-voltage main switch and adjust the A and C phase connections on the outgoing switch side until the phase (sequence) detection is consistent; S11: Press the grid-connected switch TB, and the synchronization device automatically adjusts the voltage difference, frequency, and phase difference between the low-voltage temporary mobile power supply and the low-voltage outgoing line side of the maintenance station transformer. After the synchronization detection is passed, the grid-connected switch TB is automatically closed; at this time, the low-voltage temporary mobile power supply is connected to the station transformer and automatically starts to transfer the load to the station transformer, and the secondary grid-connected operation is completed; S12: When the load transfer reaches the preset range, that is, when the output current of the transformer reaches the preset value, the low-voltage temporary mobile power supply automatically disconnects the grid-connected switch TB. At this time, the low-voltage temporary mobile power supply exits, and the low-voltage overhead line 1 is powered by the transformer; S13: Check the phases of the power supply side and the load side of the low-voltage overhead line 1 outlet switch GK1, and close the switch after confirming them; press the opening button of the mains access switch MB, and the mains access switch MB opens. At this time, the low-voltage temporary mobile power supply is completely withdrawn, and the low-voltage overhead line 1 is powered by the incoming cable of the low-voltage cable branch box of the box-type transformer; S14: Remove the public transformer terminal in the temporary access box on the pole, and move it to the transformer metering cabinet using live working. While shutting down the internal unit of the low-voltage temporary mobile power supply, remove the two sets of low-voltage flexible cables on the low-voltage overhead line 1 using live working, and store them in the tool box.

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