CN103618251A - Technology for electrified overhaul of +-800kV ultrahigh voltage direct-current transmission line - Google Patents

Abstract

The invention provides a ±800kV ultra-high voltage direct current transmission line live maintenance process. The operation method of entering the equipotential includes the following steps: After the equipotential worker wears clothes according to the dress code, climb the tower to the crossarm along the tension tower, fasten the insulating protection rope and enter the fitting joint on the side of the crossarm, and fasten the safety belt. On the hand-held insulator string; after checking that all parts of the shielding clothing are well connected, carry the potential transfer rod to prepare to enter the insulator string; Parallel movement in the form of a sheet insulator until it stops at 0.5m from the grading ring on the conductor side; quickly extend the potential transfer rod and hook it to the nearest sub-conductor or connecting fitting for potential transfer. The ±800kV UHV DC transmission line live maintenance process of the present invention realizes the completion of the project research work and the application of the research results through the research on the characteristics of the ±800kV UHV DC transmission line, filling the domestic and foreign UHV DC live operation, Blank in the field of live maintenance application technology.

Description

On-line Overhaul Technology of ±800kV UHVDC Transmission Line

【Technical field】

The invention relates to the field of ultra-high voltage power transmission and transformation, in particular to a live maintenance process for ±800kV ultra-high voltage direct current transmission lines.

【Background technique】

Transmission line operation, maintenance and repair work is an important means to grasp the operation of the power grid, discover and deal with equipment defects in time, and is also the basic work to ensure the safe and stable operation of the line. Since the UHV power grid is at the core of the operation of the entire national grid, the operation and maintenance of the UHV power grid is of great significance to ensure the safe, stable and reliable operation of the UHV power grid and even the entire national power grid.

The ±800kV UHV DC line is a brand-new voltage level. Compared with other projects, its operating voltage, line structure, window gap, etc. are quite different, especially the number of wire splits and the assembly type of insulator strings have undergone great changes. Therefore, traditional operation methods and maintenance tools cannot meet the needs of UHV DC line maintenance. If you want to carry out maintenance work and live work, you must first study a set of scientific work methods. The research on UHV DC line maintenance, live work methods and work tools will be an urgent problem to be solved.

±800kV UHV DC line maintenance work and live work is an important content of line operation maintenance work. The research results of this subject will fill in the gaps in my country's UHV DC transmission line maintenance and live work tool development and live work maintenance application technology gaps. It plays a huge role in creating the maintenance of UHV DC lines, ensuring the safety of UHV DC live work, improving the efficiency of line maintenance, and ensuring the health of equipment. Secondly, the application of live working technology will greatly reduce the number of outage hours of UHV DC lines, improve the availability of lines, and ensure the economical and reliable operation of lines.

【Content of invention】

In view of this, in order to overcome the deficiencies of the existing technology, it is necessary to provide a live maintenance process suitable for ±800kV UHV DC transmission lines.

A live overhaul process for ±800kV UHVDC transmission lines, the live overhaul process includes an operation method for entering equipotentiality, and the operation method for entering equipotentiality includes the following steps: after equipotential workers are dressed in accordance with the dress code, wear along Ascend the tension tower to the cross arm, fasten the insulation protection rope and enter the metal fitting joint on the cross arm side, tie the safety belt on the hand-held insulator string; after checking that all parts of the shielding clothing are well connected, carry the potential transfer rod and prepare to enter Insulator strings; when entering the potential, grasp one string of insulator strings with both hands, step on the other string of insulator strings with both feet, move hands and feet in parallel across two insulators at most, and stop at a distance of 0.5m from the voltage equalizing ring on the conductor side; quickly extend Potential transfer rod, hook it on the nearest sub-wire or connecting hardware for potential transfer.

In at least one of the embodiments, in the working method of entering the equipotential, the equipotential worker fastens the safety belt after entering the potential, and determines whether to release the insulation protection rope according to the operation requirements.

In at least one of the embodiments, the dress code includes wearing a full set of shielding clothing and wearing flame-resistant underwear inside the shielding clothing, and the shielding clothing includes shielding hats, shielding underwear, shielding gloves, shielding socks, shielding shoes and shielding masks.

In at least one of the embodiments, if the live repair process includes the repair and/or replacement of glass insulators, the equipotential workers must wear goggles before entering the equipotential.

In at least one of the embodiments, after the live maintenance work is completed, the equipotential worker exits the equipotential according to the following steps: After checking that all parts of the shielding clothing are well connected, hook the metal end of the potential transfer rod on the sub-conductor or the connecting hardware, Hold the insulated handle firmly with one hand, enter the insulator string and stop at 0.5m from the voltage equalizing ring on the conductor side (keep the arm straight); quickly disconnect the potential transfer rod from the sub-conductor or the connecting fitting, and retract the potential transfer rod Put it firmly on the body, and exit the equipotential return cross arm in a way that the hands and feet span at most two pieces of insulators ("cross two short three"); after checking that there is no residue on the tower, carry the insulation transmission rope down the tower.

In at least one of the embodiments, the live maintenance process includes the operation method of replacing straight double "V" insulator strings and hard turning double "L" insulator strings. The operation method of the L” insulator string includes the following steps: After entering the potential from the straight tower, use the reserved construction hole at the hanging point of the insulator string or the main material at the hanging point as the upper fulcrum of the tool tower, install the special fixture for the cross arm of the pole tower, use The two-piece plate on the wire side is used as the fulcrum of the wire side of the tool to install the big knife card; it is connected with the special clamp on the tower through the wire lifting device and the high-strength insulating pull rod to form a mechanical load transfer system for the insulator string; the back of the big knife card and the two The contact point of the connecting plate is used as a fulcrum, and the big knife card is divided into an action arm and an operating arm, and the wire lifting device is operated to carry out a small-distance lifting displacement, driving the big knife card operating arm to rotate, and driving the action arm to transfer the load on the insulator string, so that the overhauled The mechanical load of the insulator string is transferred to the wire lifting system to realize the maintenance and replacement of the insulator string.

In at least one of the embodiments, in the operation method of replacing straight double "V" insulator strings and hard-turned double "L" insulator strings, the two-connector plate on the conductor side includes L-6465S, L-8465S, Z -6450S and Z-84S two-joint plate, the thread lifting device includes a mechanical screw rod and a hydraulic screw rod.

In at least one of the embodiments, the live maintenance process includes the operation method of replacing the straight single "V" and double "V" insulator strings, and the operation method of replacing the straight single "V" and double "V" insulator strings includes The following steps: Use the reserved construction hole or the main material directly above the wire connecting plate as the cross-arm side fulcrum of the tool, install the cross-arm side tool or connecting tool; connect the high-strength insulating pull rod and hydraulic screw rod through the cross-arm side clamp And a six-split wire lifter to form two sets of independent force-bearing wire lifting systems; operate the hydraulic screw to lift the wire to transfer the mechanical load of the insulator string, and realize the maintenance and replacement of the insulator string.

In at least one of the embodiments, the live maintenance process includes the operation method of replacing the tension insulator, and the operation method of replacing the tension insulator includes the following steps: using the P-42S-120 connecting plate as a fulcrum to install the traction plate airfoil Use the insulator steel cap as the fulcrum to install the front card of the insulator closed card, and use the hydraulic screw to connect the airfoil card and the closed card to form a tight line system; use the insulator steel cap as the fulcrum to install the front card and the rear of the insulator closed card respectively The clamp is connected with the front clamp and the rear clamp of the closed clamp of the insulator by a hydraulic screw rod to form a tight line system; the steel cap of the insulator is used as the fulcrum to install the rear clamp of the closed clamp of the insulator, and the triple tension clamp is installed by using the traction plate and the fulcrum of the parallel hanging plate. A hydraulic screw rod is used to connect closed clamps and triple tension clamps to form a tightening system; operate a hydraulic screw rod to tighten the tightening system, transfer the mechanical load on the overhauled insulator, and realize the replacement and maintenance of the insulator.

The ±800kV UHV DC transmission line live maintenance process of the present invention is the first UHV live operation application technology research project at home and abroad, and the completion of the project research work has been realized through the research on the characteristics of the ±800kV UHV DC transmission line. The application of research results has filled the gaps in the field of UHV DC live work and live maintenance application technology at home and abroad.

【Description of drawings】

Fig. 1 is a schematic diagram of a method for entering equipotentiality in the live maintenance process of a ±800kV UHV DC transmission line according to a preferred embodiment of the present invention.

Fig. 2 is a schematic diagram of replacing the insulator string by the method of "lifting the line".

Figures 3A and 3B are the front view and top view of the big knife card used in the replacement of straight double "V" insulator strings and hard-turned double "L" insulator strings, respectively.

Fig. 4 is a schematic diagram of the operation of replacing straight double "V" insulator strings and hard-turned double "L" insulator strings using the big knife card in Fig. 3.

Fig. 5 is a schematic diagram of the operation method of replacing straight single "V" and double "V" insulator strings by "double lifting method".

Fig. 6 is an operation schematic diagram of a working method for replacing a tension insulator.

7A and 7B are structural schematic diagrams of the front and rear hydraulic clamps used in the method of replacing the tension insulator respectively.

8A and 8B are a partial cross-sectional view and a partial cross-sectional view from another angle of the triple strain card used in the method of replacing the strain insulator, respectively.

Fig. 9 is a schematic structural diagram of the traction plate airfoil card used in the method for replacing the tension insulator.

【Detailed ways】

In order to better understand the present invention, the invention will be described in detail below in conjunction with the accompanying drawings and specific examples.

Before the technical scheme of the present invention is introduced in detail, at first the theoretical basis of the project research is briefly stated:

(1) According to the UHV DC line tower structure, insulator string type, fitting connection form, ground wire layout, line mechanical load level and air gap form provided by China Electric Engineering Consulting Group Corporation and other design units;

(2) Based on the analysis and calculation of the overvoltage level of the ±800kV upward DC transmission line of the China Electric Power Research Institute and the experimental research on the ±800kV live working gap, the minimum safe distance for UHV DC live working, the minimum combined gap, the effective insulation length of tools and The theoretical value of insulation coordination for live work such as the number of effective insulators;

(3) According to the research on the safety protection measures for live workers of ±800kV UHV DC by China Electric Power Research Institute, the safety protection data of live workers are submitted.

When the technical project of the present invention was researched, the ±800kV UHV DC transmission project was under construction or had just entered into operation, and the maintenance and live work of DC UHV transmission lines had not yet been carried out at home and abroad. Although the China Electric Power Research Institute has carried out a lot of experimental research work on the basic technical theory of ±800kV live work, but to carry out the actual live work, it is necessary to carry out live work projects on the basis of strict theoretical demonstration and technical tests. chemical research. After carefully analyzing the design parameters of the ±800kV UHV DC transmission line upwards, fully discussing the differences and particularities of the ±800kV and previous voltage level live work, the insulation coordination parameters of the ±800kV UHV DC line live work were determined, and the liveline work was verified. Specific measures for worker protection.

First of all, entering the equipotential operation is the basic operation method of live work, and it is also the basis for the realization of other live work projects. First of all, break through the difficulty of entering the potential. According to the structural characteristics of the ±800kV DC transmission line design, the size of the tower window, the gap form and the air gap level required by the operation, and abandoning the traditional method of vertically entering the equipotential with a soft ladder hanging on the cross-arm, the design of the resistance The operation method of Zhangta entering the equipotential horizontally along the double string insulator string free operation.

The following will introduce in detail the operation method of the strain tower entering the equipotential horizontally along the free operation of the double string insulator strings.

Before entering the equipotential, equipotential workers must wear a full set of shielding clothing, including caps, underwear, gloves, socks and shoes, and wear a shielding mask. In addition, flame-retardant underwear should be worn under the shielding clothing. If the insulator string is a glass insulator, you also need to wear goggles.

After equipotential workers are dressed in accordance with the above dress code, follow the steps below to enter equipotential:

(1) After ascending the tower along the tension tower to the cross arm, fasten the insulation protection rope and enter the fitting joint on the cross arm side, and tie the safety belt to the hand-held insulator string;

(2) After checking that all parts of the shielding clothing are well connected, carry the potential transfer rod and prepare to enter the insulator string;

(3) When entering the potential, grasp a string of insulators with both hands, step on the other string of insulators with both feet, and move the hands and feet in parallel to the side of the wire to equalize the voltage by straddling two insulators at most ("cross two short three") Stop at 0.5m from the ring;

(4) Quickly stretch out the potential transfer rod and hook it to the nearest sub-wire or connecting fitting for potential transfer;

(5) After entering the potential, fasten the safety belt, and determine whether to release the insulation protection rope according to the needs of the operation. Operators wear protective ropes and safety belts for double protection. However, because the length of the protection rope is limited, it is not necessary to release it when working within the length of the protection rope after entering the potential, such as replacing the metal fittings on the wire side, the pressure equalizing ring, etc.; but if you want to work at a farther place, such as replacing the wire spacer , repair wires, etc., if the length of the protection rope is not enough, you need to remove the protection rope, and you still need to lay the protection rope when you exit after removing the protection rope.

After entering the equipotential, the live maintenance work of ±800kV DC transmission line can be carried out. For example, live replacement of anti-vibration hammers, live replacement of tension wire side fittings, live replacement of adjustable wire spacers, and live replacement of insulators, etc. The maintenance process of some of the components will be described in detail below.

After the live maintenance work is completed, the equipotential worker can exit the equipotential according to the following methods:

(1) After checking that all parts of the shielding clothing are well connected, hook the metal end of the potential transfer rod on the sub-conductor or connecting hardware, hold the insulating handle tightly with one hand, enter the insulator string and stop at a place 0.5m away from the equalizing ring on the conductor side ( keep your arms straight);

(2) Quickly disengage the connection between the potential transfer rod and the sub-conductor or connecting fittings, retract the potential transfer rod and place it firmly on the body, and exit the equipotential in the way that the hands and feet span at most two pieces of insulators ("cross two short three") return crossarm;

(3) After checking that there are no residues on the tower, carry the insulating transmission rope and go down the tower.

According to the above method of entering and exiting the potential, the components on the tension tower of the ±800kV direct current transmission line can be overhauled. Since there are many work items in the ±800kV DC transmission line, the maintenance method of some components is the same as the previous work method, so it will not be repeated here. The following will describe in detail the key operation methods of the live overhaul process such as live replacement of tension insulators.

First of all, the operating method of replacing straight double "V" insulator strings and hard-turning double "L" insulator strings with the "lever principle micro-lifting method" is explained.

In the engineering design of ±800kV UHV DC upward, a large number of general line sections adopt the assembly method of double "V" insulator strings and double "L" insulator strings. When the parts of the insulator string are defective, the mechanical load of the insulator string is generally transferred by the method of "positive lifting" to repair and replace the insulator string. Please refer to Figure 2. The so-called "positive wire lifting" method mainly refers to using the reserved construction hole (or main material) directly above the wire connecting plate as the upper fulcrum of the tool, and installing the special fixture (or connecting Tools), by connecting the wire lifting device (mechanical screw or hydraulic screw), high-strength insulating pull rod, six-split wire lifting device connected to the wire, to form a mechanical load transfer system of the insulator string. By operating the mechanical screw or hydraulic screw to tighten the load transfer system and slowly lift the wires, the mechanical load of the insulator string to be inspected is transferred to the wire lifting system to realize the inspection of the insulator string. However, the mechanical load of the wire lifting tool in this "positive wire lifting" operation method may cause the horizontal force of the insulator string on the maintenance side to be reduced, so that the wires will deviate in the opposite direction. In the case of defective insulator strings, measures should be taken to prevent the lateral displacement of the wires when the insulator strings are reset, so as to avoid the difficulty of repairing the insulator strings.

Therefore, according to the structural characteristics of the ±800kV UHV DC transmission line design, in this project, the operation of replacing the straight double "V" insulator string and the hard-turned double "L" insulator string is carried out using a large knife card and using the "leverage principle micro-lifting operation method" "Transfer the mechanical load of the insulator string. The structure of the knife card is shown in Fig. 3A, 3B. Please refer to Fig. 4, one end of the big knife card is a hook matched with the through-hole screw of the inverted triangular double plate, and the other end is an opening for an external screw. The waist connecting the hook and the opening is provided with a platform in contact with the bottom side of the inverted triangular double plate. The hook end of the big knife card is provided with a bayonet for fitting it on both sides of the inverted triangular double plate, and the root platform of the bayonet is in contact with the bottom side of the inverted triangular double plate. There are through holes for installing knurled screws on both sides of the opening of the large knife card, and the through holes are used for external screw rods. There are also grooves on the waist of the big knife card. If it is necessary to carry out pre-maintenance and overhaul of the hardware on one side of the triangular two-joint plate, firstly install the bayonet of the big knife card on the bottom of the side of the inverted triangular two-joint plate, and at the same time hook the hook on the inverted triangle The center-piercing screw in the center of the double plate, the root platform of the bayonet supports one end of the pre-maintenance and inspection of the inverted triangular double plate, so that the other end of the side of the inverted triangular double plate is the fulcrum, and the open end is the end of the lever . Then externally connect the screw mandrel at the opening end, and apply force to the opening end by manually adjusting the screw mandrel, so that the end of the lever, that is, the opening, only needs to apply a small force to move the triangular double plate on one end of the pre-maintenance and overhaul. Heavy loads are shed.

The operation method of replacing the straight double "V" insulator string and the hard-turned double "L" insulator string by using the big knife card and using the "leverage principle micro-lifting operation method" is as follows:

(1) After entering the potential from the straight tower, use the reserved construction hole (or the main material at the hanging point) at the hanging point of the insulator string as the upper fulcrum of the tool, install the cross-arm fixture of the pole tower, and use the two-piece plate on the wire side (L -6465S, or L-8465S, or Z-6450S, or Z-84S) as the wire side fulcrum of the tool to install the big knife card;

(2) Through the wire lifting device (mechanical screw or hydraulic screw), the high-strength insulating pull rod is connected with the special fixture on the tower to form a mechanical load transfer system for the insulator string;

(3) Use the contact between the card back of the big knife card and the two-piece plate as the fulcrum, and divide the big knife card into an action arm and an operating arm, operate the thread lifting device to carry out small-distance lifting displacement, drive the big knife card operating arm to rotate, and drive The action arm transfers the load on the insulator string, so that the mechanical load of the overhauled insulator string is transferred to the wire lifting system, and the maintenance of the insulator string is realized.

In the above process, the working load of double "V" insulator strings and hard-to-double "L" insulator strings is 50KN. Due to the utilization of the lever principle, the above-mentioned process can drive the operating arm of the large knife card to rotate by operating the wire lifting device to carry out a small-distance lifting displacement, and drive the action arm to transfer the load on the insulator string, which can easily and quickly replace the double "V" insulators String, hard to double "L" insulator string.

Next, the operation method of replacing straight single "V" and double "V" insulator strings by "double lifting method" will be described.

In the upward line of the ±800kV UHV DC transmission line, although the average span of the plain area of the general line section is large, most of the vertical spans are not large, so a large number of assembly forms of single "V" insulator strings are used. When the maintenance of insulator strings is required, the mechanical load of the insulator strings can be transferred by the "double lifting method". Please refer to Figure 5, the specific operation method is as follows:

(1) Use the construction hole (or main material) reserved directly above the wire connecting plate as the cross-arm side fulcrum of the tool, and install the special tool (or connection tool) for the cross-arm side;

(2) Connect high-strength insulating pull rods, hydraulic screw rods, six-split wire lifters and six-split wires through special fixtures on the cross-arm side to form two sets of independent force-bearing wire lifting systems;

(3) Operate the hydraulic screw rod to lift the wire to transfer the mechanical load of the insulator string to realize the maintenance of the insulator string.

When the straight-line tower of the upward line is at the maximum vertical span, the vertical mechanical load of the double "V" insulator string can reach 12.26T. If the mechanical load of the insulator string is transferred by using the traditional wire-lifting method, the wire-lifting load of the wire-lifting tool is 6.7T, it is difficult to guarantee to meet the requirements. Compared with the double "V" insulator strings replaced by the above-mentioned double-lifting method, compared with bearing the same load, because there are two sets of independent force-bearing wire-lifting systems for protection, the tools used in it are relatively small in load compared with the single-lifting system. , the size of the tool can be appropriately smaller, so that the gap distance between the wire and the cross arm is correspondingly increased, which is more conducive to the safe operation of live work. In addition, due to the smaller size of tools, there are also considerable advantages in terms of transportation, installation and improved maintenance efficiency.

Finally, the working method of replacing the tension insulator will be described in detail.

Replacing tension insulators and insulator strings is a routine item for transmission line maintenance and live work, and it is also a daily work for transmission line operation and maintenance. In the general maintenance process, the replacement of strain insulators and insulator strings includes the traditional method of replacing strain insulators with bottle holders and the improved method of replacing strain insulators with rotary release. The bottle support method is to install a tightening system at both ends of the insulator string for inspection and maintenance, and place a bottle holder below it, tighten the tightening system to protect the insulator string from the tension of the wire, and then disengage the insulator string from the wire and the cross arm. Link, and then place the overhaul insulator string on the ground with the bottle holder through the insulating sling, and then reverse the operation process to complete the overhaul operation. The method of rotation is to loosen the insulator with the insulator string tension adjuster first, then use the traction system to pull the insulator back to disengage the porcelain bottle on the wire side, and rotate the porcelain bottle string along the suspension point of the tower to a vertical position before placing it on the ground. Reverse the operation process to complete the maintenance work.

In the upward DC line of the ±800kV UHV DC transmission line, the tension insulator strings are designed to be assembled in horizontal triple strings. Generally, the string length is 18m, and the weight of a single string is 1.5T. Although the maintenance method of whole string replacement, the organization of construction equipment and the actual operation on site by using the traditional tension insulator string replacement method are technically achievable, but as a routine maintenance, especially live work is used for maintenance. Still have considerable difficulty. Therefore, this project adopts the operation method of single-piece replacement based on the design structure of the triple-strength tensile structure of the UHV DC project and the insulation form (disk-shaped porcelain insulators) adopted. Please refer to Figure 6, the specific operation process is as follows:

(1) Use the joint plate (P-42S-120 type) as the fulcrum to install the traction plate airfoil card (as shown in Figure 9), and use the insulator steel cap as the fulcrum to install the insulator closed card front card (as shown in Figure 7A ) Use a hydraulic screw rod to connect the airfoil card and the closed card to form a tightening system;

(2) Use the steel cap of the insulator as the fulcrum to install the front card and the rear card of the insulator closed card respectively (as shown in Figure 7A and 7B), and connect the front card and the rear card of the insulator closed card with a hydraulic screw rod to form a tight line system;

(3) Use the steel cap of the insulator as the fulcrum to install the insulator closed card rear card, and use the traction plate (QY-42S type) and parallel hanging plate (P-4215S) as the fulcrum to install the triple tension-resistant special card (as shown in Figure 8 ), using a hydraulic screw rod to connect the closed card and the triple tension card to form a tensioning system;

(4) Operate the hydraulic screw rod to tighten the tightening system, transfer the mechanical load on the overhauled insulator, and realize the replacement and overhaul of the insulator.

Through the above process, the single-piece replacement of the tension insulator can be realized, which ensures the convenient operation of the tension insulator as a routine maintenance.

In summary, the ±800kV UHV DC transmission line live overhaul technology of the present invention is the first UHV live work application technology research project at home and abroad. Blank in the field of high-voltage DC live work and live maintenance application technology. The specific operation method in the ±800kV UHV DC transmission line live maintenance process of the present invention covers the work content of ±800kV UHV DC transmission line maintenance and live work routine maintenance, wherein the lever principle micro-lifts and transfers the multi-connected insulator string load operation The application of the method and large-tonnage combined hydraulic screw rod to live work, especially to the equipotential work method of ±800kV UHV DC live, is a major breakthrough in the field of live work application technology.

The above-mentioned embodiments only express several implementation modes of the present invention, and the description thereof is relatively specific and detailed, but should not be construed as limiting the patent scope of the present invention. It should be pointed out that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent for the present invention should be based on the appended claims.

Claims (9)

1. A ± 800kV UHV DC transmission line live overhaul technique, said live overhaul technique includes entering an equipotential operating method, and said entering an equipotential operating method may further comprise the steps: After the equipotential workers are dressed according to the dress code, they climb the tower to the cross arm along the tension tower, fasten the insulation protection rope and enter the metal connection on the cross arm side, and tie the safety belt on the hand-held insulator string; After checking that all parts of the shielding clothing are well connected, carry the potential transfer rod and prepare to enter the insulator string; When entering the potential, grasp one string of insulators with both hands, step on the other string of insulators with both feet, move hands and feet in parallel across two insulators at most, and stop at a distance of 0.5m from the equalizing ring on the conductor side; Quickly extend the potential transfer rod and hook it to the nearest sub-wire or connecting hardware for potential transfer. 2. The live overhaul process for ±800kV UHVDC transmission lines according to claim 1, characterized in that: in the operation method of entering the equipotential, the equipotential workers fasten their safety belts after entering the potential, and according to the operation needs To determine whether to release the insulation protection rope. 3. The live maintenance process for ±800kV UHVDC transmission lines according to claim 1, characterized in that: the dress code includes wearing a full set of shielding clothing and wearing flame-retardant underwear inside the shielding clothing, and the shielding clothing includes shielding caps, Shielding clothing, shielding gloves, shielding socks, shielding shoes, and shielding masks. 4. The ±800kV UHV DC transmission line live overhaul process according to claim 3, characterized in that: if the live overhaul process includes the overhaul and/or replacement of glass insulators, the equipotential workers will also Wear goggles. 5. The live overhaul process for ±800kV UHV DC transmission lines according to claim 1, characterized in that after the live overhaul work is completed, the equipotential worker exits the equipotential according to the following steps: After checking that all parts of the shielding clothing are well connected, hook the metal end of the potential transfer rod on the sub-conductor or the connecting hardware, hold the insulating handle tightly with one hand, enter the insulator string and stop at a place 0.5m away from the equalizing ring on the conductor side (keep the arm extended straight state); Quickly disengage the connection between the potential transfer rod and the sub-conductor or connecting fittings, retract the potential transfer rod and place it firmly on the body, and withdraw the equipotential return to the cross arm with hands and feet in a way that spans at most two pieces of insulators; After checking that there is no remnant on the tower, carry the insulating transmission rope down the tower. 6. The live overhaul process for ±800kV UHVDC transmission lines according to any one of claims 1 to 5, characterized in that the live overhaul process includes replacing straight double "V" insulator strings, hard turning double "L" "The operation method of the insulator string, the operation method of replacing the straight double "V" insulator string and the hard-turned double "L" insulator string includes the following steps: After entering the potential from the straight tower, use the reserved construction hole at the hanging point of the insulator string or the main material at the hanging point as the upper fulcrum of the tool, install the special fixture for the cross arm of the pole tower, and use the two-piece board on the wire side as the wire side support of the tool Click to install the big knife card; The mechanical load transfer system of the insulator string is composed of a wire lifting device, a high-strength insulating pull rod and a special fixture on the tower; Use the contact between the card back of the big knife card and the two-piece plate as the fulcrum, and divide the big knife card into an action arm and an operating arm, operate the thread lifting device to carry out small-distance thread lifting displacement, drive the big knife card operating arm to rotate, and drive the action arm to transfer The load on the insulator string transfers the mechanical load of the overhauled insulator string to the wire lifting system to realize the overhaul and replacement of the insulator string. 7. The live overhaul process for ±800kV UHVDC transmission lines according to claim 6, characterized in that: in the operation method of replacing straight double "V" insulator strings and hard-turning double "L" insulator strings, the The two connecting plates on the wire side include L-6465S, L-8465S, Z-6450S and Z-84S two connecting plates, and the wire lifting device includes a mechanical screw rod and a hydraulic screw rod. 8. The ±800kV UHV DC transmission line live maintenance process according to any one of claims 1 to 5, characterized in that the live maintenance process includes replacing the straight line single "V" and double "V" insulator strings Operation method, the operation method for replacing the straight line single "V" and double "V" insulator strings includes the following steps: Use the reserved construction hole or the main material directly above the wire connecting plate as the cross-arm side fulcrum of the tool, and install the cross-arm side tool or connecting tool; Connect high-strength insulating pull rods, hydraulic screw rods, six-split wire lifters and six-split wires through the clamps on the side of the cross arm to form two sets of independent force-bearing wire lifting systems; Operate the hydraulic screw to lift the wire to transfer the mechanical load of the insulator string to realize the maintenance and replacement of the insulator string. 9. The live overhaul process for ±800kV UHVDC transmission lines according to any one of claims 1 to 5, characterized in that, the live overhaul process includes an operation method of replacing strain insulators, and the replacement of strain insulators The working method includes the following steps: Use the P-42S-120 connecting plate as the fulcrum to install the traction plate airfoil card, use the insulator steel cap as the fulcrum to install the front card of the insulator closed card, and use the hydraulic screw to connect the airfoil card and the closed card to form a tightening system; Use the steel cap of the insulator as the fulcrum to install the front and rear clamps of the insulator closed clamp respectively, and connect the front clamp and the rear clamp of the insulator closed clamp with a hydraulic screw rod to form a tightening system; Use the steel cap of the insulator as the fulcrum to install the insulator closed card rear card, use the traction plate and the parallel hanging plate fulcrum to install the triple tension card, and use the hydraulic screw to connect the closed card and the triple tension card to form a tensioning system; Operate the hydraulic screw to tighten the wire tightening system, transfer the mechanical load on the overhauled insulator, and realize the replacement and overhaul of the insulator.

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