A method for de-icing the ground wire without power outage of the conductor

Abstract

The present invention provides a method for deicing the ground wire without power interruption to the conductor, comprising the following steps: determining the scope and length of the ground wire deicing; determining the deicing duration, and obtaining the maximum and minimum values of the ground wire deicing current; obtaining the maximum length of a single deicing according to the deicing current value limit, and dividing the deicing scope into single or multiple deicing sections; selecting the ground wire deicing connection mode for this section according to the length of the deicing section and the position of the deicing power supply access point; calculating the required deicing capacity range and deicing voltage range for each section according to the ground wire deicing connection mode, and determining the rated current, rated voltage and rated capacity of the deicing power supply; selecting the deicing power supply access mode; installing insulators on the ground wire suspension string and tension string, and installing insulated drainage line clamps on the drainage line; installing arc horns on the insulators of the ground wire deicing string; connecting a ground wire induced voltage suppression device and performing the ground wire deicing operation.

Description

Technical Field

[0001] The present invention relates to the technical field of ground wire de-icing, and more particularly to a method for de-icing a ground wire without power outage of a conductor. Background Art

[0002] Ice and snow covering, as a special meteorological condition, has seriously affected the safe operation of many overhead transmission lines around the world. Affected by the macroclimate and microtopography and micro-meteorological conditions in China, ice disaster accidents occur frequently. The conductors and ground wires of transmission lines are severely covered with ice, resulting in tower collapse and wire breakage accidents, causing great damage to the power grid.

[0003] Since the ground wire does not carry current under ice and snow weather, it is more likely to be covered with ice than the conductor. Analyzing from the damage conditions of ice disaster accidents in recent years, icing often first causes damage or slippage of the overhead ground wire and damage to the ground wire support, leading to line tripping and outage, and then triggering accidents such as tower damage. After statistics, the proportion of ground wire faults in line icing faults is much higher than that of conductor faults, and the overhead ground wire is the most vulnerable link in the transmission line. Therefore, realizing the de-icing of the overhead ground wire is of great significance for improving the overall anti-icing ability of the transmission line and ensuring the power supply reliability of the power grid.

[0004] The ground wire de-icing method is usually electrothermal de-icing after the ground wire is electrified. The de-icing power supply used is generally located in the substations at both ends of the line. Existing ground wire de-icing schemes all need to form a de-icing loop by connecting the ground wire in series with the conductor to connect to the de-icing device in the substation. Therefore, the conductor also needs to be out of service during ground wire de-icing, which affects the normal power supply of the line and causes the loss of the line transmission function during de-icing. Summary of the Invention

[0005] The present invention aims to at least solve one of the technical problems in the prior art that when de-icing the ground wire, it is necessary to stop the conductor from operating, which affects the normal power supply of the line and causes the loss of the line transmission function during de-icing.

[0006] To this end, the present invention provides a method for de-icing a ground wire without power outage of a conductor.

[0007] The present invention provides a method for de-icing a ground wire without power outage of a conductor, including the following steps:

[0008] S1. Determine the section where the ground wire needs to be de-iced according to the division of the engineering ice area, the selection of the ground wire, and the engineering microtopography and micro-meteorological area, and determine the scope and length of the ground wire de-icing;

[0009] S2. Determine the de-icing duration according to the relationship between the environmental temperature, wind speed, ice thickness and de-icing current, and obtain the maximum and minimum values of the ground wire de-icing current;

[0010] S3. Based on the ice melting current value limit, obtain the maximum length Lmax of a single ice melting operation. Divide the ice melting range into one or more ice melting sections according to Lmax.

[0011] S4. According to the length of the ice melting section and the position of the ice melting power supply access point, select the grounding wire ice melting connection method for this section. The grounding wire ice melting connection method includes a series ice melting connection method and a parallel ice melting connection method.

[0012] S5. According to the selected grounding wire ice melting connection method for the ice melting section, calculate the required ice melting capacity range and ice melting voltage range for each section, and determine the rated current, rated voltage, and rated capacity of the ice melting power supply.

[0013] S6. Install insulators on the grounding wire suspension strings and strain strings, and install insulating drainage wire clamps on the drainage wires to achieve the insulation transformation of the grounding wire.

[0014] S7. Install arc horns on the insulators of the grounding wire ice melting suspension strings and strain strings.

[0015] S8. Perform the grounding wire ice melting operation.

[0016] For a method of non-stop power supply grounding wire ice melting according to the above technical solution of the present invention, it may further have the following additional technical features:

[0017] In the above technical solution, when the length of the ice melting section is not greater than the maximum length Lmax of a single ice melting operation, this ice melting section adopts the series ice melting connection method. The series ice melting connection method includes a first series ice melting connection method and a second series ice melting connection method.

[0018] When the ice melting section adopts the first series ice melting connection method, connect the two grounding wires to the positive and negative poles of the ice melting power supply respectively at the starting end of the ice melting section, and connect the two grounding wires through a series wire at the end of the ice melting section to form a series circuit.

[0019] When the ice melting section adopts the second series ice melting connection method, connect one of the two grounding wires to the positive and negative poles of the ice melting power supply at any point within the ice melting section, cut off the grounding wires on both sides of the grounding wire where the ice melting power supply is connected, and connect the two grounding wires through a series wire at the starting end and the end of the ice melting section respectively to form a series circuit.

[0020] In the above technical solution, when the ice melting section adopts the series ice melting connection method, the total resistance of the ice melting section is the sum of the resistance values of the two grounding wires within the ice melting section.

[0021] In the above technical solution, when the length of the ice melting section is greater than the maximum length Lmax of single - time ice melting, the ice melting section adopts a parallel ice melting connection method. The mid - points of the resistances of the two ground wires in the ice melting section are respectively connected to the positive and negative poles of the ice melting power supply. At the start and end of the ice melting section, the two ground wires are connected in series through a series wire to form a parallel circuit.

[0022] In the above technical solution, when the ice melting section adopts a parallel ice melting connection method, the total resistance of the ice melting section is half of the sum of the resistance values of the two ground wires in the ice melting section.

[0023] In the above technical solution, when the ice melting section adopts a parallel ice melting connection method, according to the severity of icing, unilateral ice melting of the ice melting section can be carried out. That is, at the start of the ice melting section, the two ground wires are connected in series through a series wire, and the two ground wires at the end are not connected, or at the end of the ice melting section, the two ground wires are connected in series through a series wire, and the two ground wires at the start are not connected.

[0024] In the above technical solution, in S5, when the ice melting section adopts a series ice melting connection method, the ice melting voltage range of this section is IminR~ImaxR, the ice melting capacity range is Imin 2 R~Imax 2 R, the rated current required for the ice melting power supply is Imax, the rated voltage is ImaxR, and the rated capacity is Imax 2 R;

[0025] When the ice melting section adopts a parallel ice melting connection method, the ice melting voltage range of this section is IminR~ImaxR, the ice melting capacity range is 2Imin 2 R~2Imax 2 R, the rated current required for the ice melting power supply is 2Imax, the rated voltage is ImaxR, and the rated capacity is 2Imax 2 R;

[0026] Among them, Imin is the minimum value of the ground wire ice melting current obtained in S2, Imax is the maximum value of the ground wire ice melting current obtained in S2, and R is the total resistance of the ice melting section.

[0027] In the above technical solution, it further includes:

[0028] Select an ice melting power supply according to the actual situation on - site of the line and the rated current, rated voltage and rated capacity of the ice melting power supply obtained in S5. The ice melting power supply includes a mobile ice melting vehicle, an offline fixed ice melting device, an ice melting power supply in a substation near the connection of a newly built tie line, etc.

[0029] In the above technical solution, it further includes: installing an induced voltage suppression device on the ground wire.

[0030] In the above technical solution, in S6, after the ground wire is insulated, at least one point of the ground wire in the ice melting section is grounded when not melting ice, and the grounding point is disconnected to form an insulated circuit when melting ice.

[0031] In summary, due to the adoption of the above technical features, the beneficial effects of the present invention are as follows:

[0032] The structure of the present invention is simple and the design is scientific and reasonable. A new method for melting ice on the ground wire is invented. The ground wire forms an ice melting circuit alone without the participation of the conductor. That is, the ice melting of the ground wire can be realized without power outage of the conductor.

[0033] After adopting the new ice melting technology of "melting ice on the ground wire without power outage of the conductor", the present invention can form a complete circuit with two ground wires for ice melting according to the length and section distribution of the ground wire on the premise of ensuring the safety and reliability of the transmission line without reduction. It effectively solves the problem that the conductor needs to be shut down in the existing ground wire ice melting technology. The conductor will maintain the power transmission function while the ground wire is melting ice, reducing the power outage loss of the transmission line.

[0034] The method for connecting wires for melting ice on the ground wire without power outage of the conductor in the present invention reduces a large number of conductor and ground wire connection operations before and after ice melting, saving the ice melting time.

[0035] In the present invention, series ice melting once or parallel ice melting once can be selected according to the length of the ice melting section and the ice melting power access point, and the ice melting of ground wires with different lengths can be completed efficiently and reliably.

[0036] In the parallel ice melting connection mode in the present invention, the ground wires on both sides of the access point can be connected in parallel for ice melting at one time, or a single-side ground wire section can be selected for separate ice melting according to the real-time icing severity.

[0037] For the selection of the ice melting power source in the present invention, various factors such as the current, voltage, capacity required for ice melting and the actual on-site situation can be comprehensively considered, and methods such as selecting a mobile ice melting vehicle, adding a new fixed ice melting device under the line, or building a new ice melting connection line to connect to the ice melting power source device in the nearby substation can be adopted.

[0038] The present invention considers the influence of the induced current of the ground wire on ice melting without power outage, and proposes that it is necessary to study the induced voltage of the ground wire under different operating states of the conductor, and install a device for suppressing the induced voltage of the ground wire to ensure the reliability of the self-starting of the ice melting power source.

[0039] The present invention considers the method for insulating the ground wire, and ensures the insulated connection between the ground wire in the ice melting section and the iron tower.

[0040] In the present invention patent, an arc horn (discharge gap) is installed on the insulator of the ground wire ice melting string. At the same time, when not melting ice, single-point or multi-point grounding of the ground wire in the ice melting section is considered to reduce the influence on the lightning protection performance of the line after the insulation transformation of the ground wire in the ice melting section.

[0041] Additional aspects and advantages of the present invention will become apparent in the following description section or be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The above and / or additional aspects and advantages of the present invention will become apparent and be readily understood from the description of embodiments in conjunction with the following drawings, in which:

[0043] Figure 1 is a flowchart of a method for deicing a ground wire without power outage of a conductor according to an embodiment of the present invention.

[0044] Figure 2 is a wiring schematic diagram of a first series deicing wiring method in a method for deicing a ground wire without power outage of a conductor according to an embodiment of the present invention;

[0045] Figure 3 is a wiring schematic diagram of a second series deicing wiring method in a method for deicing a ground wire without power outage of a conductor according to an embodiment of the present invention;

[0046] Figure 4 is a wiring schematic diagram of a parallel deicing wiring method in a method for deicing a ground wire without power outage of a conductor according to an embodiment of the present invention;

[0047] Figure 5 is a schematic diagram of a ground wire deicing insulation string and an arc horn (discharge gap) added in a method for deicing a ground wire without power outage of a conductor according to an embodiment of the present invention;

[0048] Figure 6 is a schematic diagram of a ground wire deicing insulation lead-down grounding in a method for deicing a ground wire without power outage of a conductor according to an embodiment of the present invention;

[0049] Figure 7 is a schematic diagram of the connection of a ground wire induced voltage suppression device in a method for deicing a ground wire without power outage of a conductor according to an embodiment of the present invention;

[0050] Figure 8 is a schematic diagram of the division of a deicing section in a method for deicing a ground wire without power outage of a conductor according to an embodiment of the present invention;

[0051] Wherein, Figures 1 to 8 the corresponding relationship between the reference numerals in the drawings and the component names is as follows:

[0052] 1, positive temporary connection wire; 2, negative temporary connection wire; 3, series wire. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0053] To better understand the above objects, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, without conflict, the embodiments of the present application and the features in the embodiments can be combined with each other.

[0054] In the following description, many specific details are set forth to facilitate a thorough understanding of the present invention. However, the present invention can be practiced in other ways different from those described herein. Therefore, the scope of protection of the present invention is not limited by the specific embodiments disclosed below.

[0055] The following refers to Figures 1 to 8 to describe a method for de-icing the ground wire without power interruption of the conductor according to some embodiments of the present invention.

[0056] Some embodiments of the present application provide a method for de-icing the ground wire without power interruption of the conductor.

[0057] As Figures 1 to 8 shown, the first embodiment of the present invention proposes a method for de-icing the ground wire without power interruption of the conductor, including the following steps:

[0058] S1. Determine the section where the ground wire needs to be de-iced according to the division of the engineering ice area, the selection of the ground wire, the engineering micro-topography and micro-meteorological regions, etc., and determine the scope and length of the ground wire de-icing.

[0059] S2. Determine the de-icing duration according to the relationship between the environmental temperature, wind speed, ice thickness and the typical ground wire de-icing current, and obtain the maximum value Imax and the minimum value Imin of the ground wire de-icing current.

[0060] S3. According to the limit value of the de-icing current value, obtain the maximum length Lmax of a single de-icing, determine the longest length of the de-icing section according to Lmax, the longest length of the de-icing section does not exceed twice of Lmax, and divide the de-icing scope into single or multiple de-icing sections, and the length of each section is L1, L2, L3... Ln.

[0061] S4. Select the ground wire de-icing wiring method for this section according to the length of the de-icing section and the position of the de-icing power access point, and the ground wire de-icing wiring method includes a series de-icing wiring method and a parallel de-icing wiring method.

[0062] When the length of the de-icing section is not greater than the maximum length Lmax of a single de-icing, the series de-icing wiring method is adopted for this de-icing section, and the series de-icing wiring method includes a first series de-icing wiring method and a second series de-icing wiring method.

[0063] According to the selected length L1 of the ground wire de-icing section, if L1 is short, that is, L1 is less than Lmax, the first series de-icing wiring method is adopted for this de-icing section, as Figure 2As shown, at the starting end of the ice melting section, two ground wires are respectively connected to the positive and negative poles of the ice melting power supply through the positive temporary connection wire 1 and the negative temporary connection wire 2. At the end of the ice melting section, the two ground wires are connected through the series wire 3 to form a series circuit;

[0064] According to the selected length L2 of the ground wire ice melting section, if L2 is short, that is, L2 is less than Lmax, the second series ice melting connection method is adopted for this ice melting section, as Figure 3 shown. At any point within the ice melting section, one of the two ground wires is connected to the positive and negative poles of the ice melting power supply through the positive temporary connection wire 1 and the negative temporary connection wire 2. The ground wires on both sides of the ice melting power supply connection to the ground wire are cut off, that is, the ground wires on both sides of the ice melting power supply connection point are not connected. At the starting end and the end of the ice melting section, the two ground wires are respectively connected through the series wire 3 to form a series circuit.

[0065] When the series ice melting connection method is adopted for the ice melting section, the total resistance of the ice melting section is the sum of the resistance values of the two ground wires within this section of the ice melting section.

[0066] According to the selected length L3 of the ground wire ice melting section, if L3 is long, that is, L3 is greater than Lmax and less than 2Lmax, the parallel ice melting connection method is adopted for this ice melting section, as Figure 4 shown. The midpoints of the resistances of the two ground wires within the ice melting section are respectively connected to the positive and negative poles of the ice melting power supply through the positive temporary connection wire 1 and the negative temporary connection wire 2. At the starting end and the end of the ice melting section, the two ground wires are respectively connected through the series wire 3 to form a parallel circuit.

[0067] When the parallel ice melting connection method is adopted for the ice melting section, the total resistance of the ice melting section is half of the sum of the resistance values of the two ground wires within the ice melting section.

[0068] When the parallel ice melting connection method is adopted for the ice melting section, according to the severity of the ice cover, unilateral ice melting can be carried out on the ice melting section. That is, if only the ground wire on the side with severe ice cover within the section needs to be melted, then connect the series wire at the end of this side of the ground wire, and at the same time disconnect the series wire at the end of the ground wire on the non - melting side; that is, at the starting end of the ice melting section, the two ground wires are connected through the series wire, and the two ground wires at the end are not connected, or, at the end of the ice melting section, the two ground wires are connected through the series wire, and the two ground wires at the starting end are not connected.

[0069] S5. According to the selected ground wire ice melting connection method for the ice melting section, calculate the required ice melting capacity range and ice melting voltage range for each section, and determine the rated current, rated voltage and rated capacity of the ice melting power supply;

[0070] In S5, when the series ice melting connection method is adopted for the ice melting section, the ice melting voltage range for this section is IminR~ImaxR, and the ice melting capacity range is Imin 2 R~Imax2 For R, the rated current required for the ice melting power supply is Imax, the rated voltage is ImaxR, and the rated capacity is Imax 2 R;

[0071] When the parallel ice melting connection method is adopted for the ice melting section, the ice melting voltage range of this section is IminR~ImaxR, and the ice melting capacity range is 2Imin 2 R~2Imax 2 For R, the rated current required for the ice melting power supply is 2Imax, the rated voltage is ImaxR, and the rated capacity is 2Imax 2 R;

[0072] Among them, Imin is the minimum value of the ground wire ice melting current obtained in S2, Imax is the maximum value of the ground wire ice melting current obtained in S2, and R is the total resistance of the ice melting section.

[0073] Select the ice melting power supply according to the actual situation of the line site and the rated current, rated voltage and rated capacity required for the ice melting power supply obtained in S5. The ice melting power supply includes a mobile ice melting vehicle, a newly added fixed ice melting device under the line, and an ice melting power supply device in the nearby substation connected by a newly built ice melting connection line.

[0074] When connecting the ground wire of the ice melting section and the ice melting power supply, it is necessary to consider the induced voltage existing on the fully insulated ground wire when the conductor is not de-energized.

[0075] The ground wire induced voltage refers to when the ground wire is insulated and has no grounding point, due to the electrostatic induction or harmonic influence of the conductor in different operating states, an induced voltage will be generated on the ground wire. When the ground wire is melting ice, the ground wire forms an insulated ice melting loop, and this induced voltage will affect the access and start of the ice melting power supply. Therefore, an induced voltage suppression device is installed on the ground wire to ensure the reliable connection between the ice melting power supply and the ground wire.

[0076] S6. Install insulators on the ground wire suspension string and strain string, and install insulated drainage wire clamps on the drainage wire to realize the insulation transformation of the ground wire;

[0077] The ground wire of general lines adopts the method of grounding tower by tower or grounding at one point with segmented insulation. For the ground wire to melt ice, the ground wire of the ice melting section must be insulated. Insulators should be installed on both the ground wire suspension string and the strain string. When insulating the ground wire, double insulator strings are preferably used; both the ground wire and the optical cable adopt insulated drainage wire clamps for drainage on the iron tower to ensure the insulation between the ground wire (optical cable) of the ice melting section and the iron tower;

[0078] The insulation level of the ground wire insulator needs to be coordinated with the ground wire ice melting voltage value to realize the insulation of the ground wire while minimizing the total length of the insulator string as much as possible.

[0079] S7. Install arcing horns on the insulators of the ground wire ice melting suspension string and strain string;

[0080] Arcing horns are installed on the insulators of the ground wire ice-melting suspension string and tension string. When lightning strikes, the discharge gap of the arcing horn is broken down during the lightning precursor discharge stage, making the ground wire grounded, thus not affecting its lightning protection function; when a grounding fault occurs in the conductor, the ground wire gap is broken down, playing a role of shunting.

[0081] In S6, after the ground wire is insulated, at least one point of the ground wire in the ice-melting section is grounded when the ice is not melting, and the grounding point is disconnected during ice melting to form an insulation loop, thereby further reducing the impact of the ground wire insulation transformation on the lightning protection performance of the line.

[0082] S8. According to the above steps, select a suitable wiring method and ice-melting power supply, connect the ground wire induction voltage suppression device, complete the connection between the ground wire and the ice-melting power supply, and then perform the ground wire ice-melting operation.

[0083] The second embodiment of the present invention provides a method for melting ice on a ground wire without power outage, and based on the first embodiment, Figures 1 to 8 As shown, the specific steps include:

[0084] S1. Determination of ice-melting sections: Collect and investigate the climate characteristics along the route, focusing on ice-covered sections with relatively scarce data, ice-prone areas, heavy ice sections, and ice-boundary sections, especially the ice-covered conditions during strong cold waves in recent years; at the same time, conduct a detailed investigation on the ice-covered design values and disaster conditions of lines of different grades near the route, understand the ice-covered conditions during ice disasters, micro-meteorological and micro-topographic points, etc., and determine the sections where ground wire ice melting is required for the project.

[0085] S2. Determination of ice-melting current: The ice-melting current of overhead lines is related to factors such as ambient temperature, wind speed, ice thickness, and ice-melting time. Using existing methods and previous engineering experience, select a mathematical model for ice-melting calculations to calculate the ice-melting time and critical ice-melting current under various conditions. At the same time, carry out relevant ice-melting tests, compare the theoretically calculated ice-melting time, current, etc. with the test parameters, and obtain more accurate and reasonable ice-melting current and ice-melting time. For example, according to the ice-melting time of 1 hour, calculate the ice-melting current range of all ground wires in the ice-melting range when melting different ice covers, and obtain the minimum value Imin and maximum value Imax of this ice-melting current, as shown in the following table:

[0086]

[0087] S3. According to the above ice melting current value and ice melting voltage value limits, the maximum length Lmax of one-time ice melting can be obtained. According to Lmax and the importance of ice melting in special sections (if any), the ice melting range is divided into single or multiple ice melting sections, and the length of each section is L1, L2, L3... Ln (L1, L2, L3... Ln ≤ 2 × Lmax).

[0088] When the ice melting current in the ice melting section is Imin = 200A and Imax = 600A in the above table, and the ice melting voltage is selected as ±25kV (considering that the voltage values of current conventional ice melting materials and equipment are within ±25kV), the total resistance of the ground wires on both sides of the maximum ice melting section does not exceed 83Ω (50kV / 0.6kA), and the maximum Lmax of this ice melting is obtained (the total resistance of the ground wires on both sides of Lmax is 83Ω). Then, referring to the line conditions, the ice melting divided sections are as Figure 8 shown, where the length of the ice melting section L1 is L1, L1 ≤ Lmax; the length of the ice melting section L2 is L2, L2 ≤ Lmax; the length of the ice melting section L3 is L3, Lmax ≤ L3 ≤ 2Lmax.

[0089] S4. Design an efficient and reliable ground wire ice melting wiring method for this section according to the length of different ice melting sections and the position of the power access point;

[0090] For the ice melting section L1 with L1 ≤ Lmax, it can be considered to melt ice once by connecting the two ground wires in series in this section. Further determine the ice melting power access point according to the topography and landform of this section. Usually, comprehensively select the tower position with better terrain conditions, relatively smaller ice areas, more convenient for construction and operation personnel to work, or the tower position closer to the ice melting device to set the ice melting power access point;

[0091] If the access point is at the starting point or the ending point of the ice melting section (taking the access point at the starting point as an example), it can be considered to adopt the first series ice melting wiring method for the two ground wires, and the total resistance R1 of the ice melting section is the sum of the resistance values of the two ground wires;

[0092] For the ice melting section L2 with L2 ≤ Lmax, it can be considered to melt ice once by connecting the two ground wires in series in this section. Further determine the ice melting power access point according to the topography and landform of this section. Usually, comprehensively select the tower position with better terrain conditions, relatively smaller ice areas, more convenient for construction and operation personnel to work, or the tower position closer to the ice melting device to set the ice melting power access point;

[0093] If the access point is at any point in the middle of the ice melting section, it can be considered to adopt the second series ice melting wiring method for the two ground wires, and the total resistance R2 of the ice melting section is the sum of the resistance values of the two ground wires;

[0094] The length L3 of the ice melting section L3 satisfies Lmax ≤ L3 ≤ 2Lmax. A parallel ice melting connection method can be considered for the two ground wires. The ice melting power supply access point is at the mid - value of the resistance of the two ground wires in this section, and the total resistance R of the ice melting section b is half of the sum of the resistance values of the two ground wires.

[0095] S5. According to the ice melting connection method of the ground wire selected for the ice melting section, calculate the required ice melting voltage range and ice melting capacity range for each section, and determine the rated current, rated voltage, and rated capacity of the ice melting power supply;

[0096] The ice melting voltage range of the ice melting section L1 is IminR1~ImaxR1, and the ice melting capacity range is Imin 2 R1~Imax 2 R1. The required rated current of the ice melting power supply is Imax, the rated voltage is ImaxR1, and the rated capacity is Imax 2 R1;

[0097] The ice melting voltage range of the ice melting section L2 is IminR2~ImaxR2, and the ice melting capacity range is Imin 2 R2~Imax 2 R2. The required rated current of the ice melting power supply is Imax, the rated voltage is ImaxR2, and the rated capacity is Imax 2 R2;

[0098] The ice melting voltage range of the ice melting section L3 is IminR b ~ImaxR b , and the ice melting capacity range is 2Imin 2 R b ~2Imax 2 R b . The required rated current of the ice melting power supply is 2Imax, the rated voltage is ImaxR b , and the rated capacity is 2Imax 2 R b ;

[0099] During actual operation of the ice melting section L3, it is also possible to select a single - side ice melting section for separate ice melting according to the ice - covering situation of the line on - site. For example, when an actual cold wave comes, if only the ground wires of the section on the left side of the power supply access point are severely ice - covered and in urgent need of ice melting, then only the left - hand ground wire section can be considered for separate ice melting. Just keep the series line at the end of this ice melting section connected, and at the same time, disconnect the series line at the end of the non - ice - melting section on the right side. At this time, the ice melting current is Imin~Imax, the voltage is IminR b ~ImaxR b , and the capacity is Imin 2 R b ~Imax 2 Rb 。

[0100] In summary, the ice melting parameters in this ice melting area are shown in the following table:

[0101]

[0102] Selection of ice melting power supply: The selection of the ice melting power supply is obtained through comprehensive analysis and consideration based on the current, voltage and capacity of the ice melting device required for this ice melting section, with reference to the situation of the line ice melting section. If the ice melting section is short, the required ice melting capacity is small, and the location of the ice melting power supply access point is easy to reach, a mobile ice melting vehicle can be considered. When melting ice, drive the ice melting vehicle to the tower position below the access point and connect the ground wires on both sides for power supply; if the ice melting section is long, the required ice melting capacity is large, or the location of the ice melting power supply access point is inconvenient, a fixed ice melting device can be newly added under the tower position of the access point, or a new ice melting connection line can be built to connect the ice melting device in the nearby substation.

[0103] S6. To achieve ice melting for the ground wire, the ground wire in the ice melting section must be insulated. Insulators should be installed on both the suspension string and the strain string of the ground wire, and composite insulators or disc insulators can be used. When insulating the ground wire, a double insulator string is preferably used. On the premise of minimizing the string length as much as possible, the connection between string components is required to be reliable, and it should rotate flexibly in both the line direction and the direction perpendicular to the line without jamming or sticking. For example Figure 5 is the common wiring method for the ice melting insulation string of the ground wire.

[0104] In addition to installing insulators on the suspension string and the strain string of the ground wire for insulation, insulated drainage clamps should also be used for the wire routing and drainage of the ground wire (optical cable) on the iron tower to ensure the insulation between the ground wire (optical cable) in the ice melting section and the iron tower. The sag and length of the ground wire jumper in the ice melting section are determined by simulation. Considering the wind deflection, the electrical distance between the jumper and the tower members should not be less than 0.2m, and the clearance between the OPGW optical cable and the part of the ground wire leading down to the tower body should not be less than 0.3m.

[0105] S7. Selection of the ground wire arcing horn (discharge gap): Arcing horns need to be installed on the insulators of the suspension string and the strain string for ground wire ice melting. During lightning strikes, the discharge gap of the ground wire arcing horn is broken down during the lightning leader discharge stage, making the ground wire in a grounded state, so it does not affect its lightning protection function. When a ground fault occurs on the conductor, the ground wire gap is broken down, playing a role in shunting.

[0106] When a lightning strike occurs on the tower or the insulated ground wire, the arc horn discharge gap of the ground wire will flash over. There is no obvious difference in the lightning attracting effect of the insulated ground wire compared with the ground wires with tower-by-tower grounding and sectional grounding. When the air gap distance between the ground wire and the tower insulation is 60 mm to 200 mm, the impact on the backflashover lightning withstand level of the line is relatively small. Therefore, after installing an arc horn (with a discharge gap between 60 mm and 200 mm) on the ice melting insulation string of the ground wire, the impact on the lightning performance of the line can be ignored. Referring to the test conclusions and past engineering experience, the discharge gap of the ground wire insulator adopts a fixed gap, and the distance value is between 60 - 120 mm.

[0107] During normal operation of the line, the induced voltage of the insulated ground wire is small. When a line fault occurs, the induced voltage on the ground wire is large. At the same time, considering the important role of the ground wire in line lightning protection, after the insulation transformation of the ground wire section for ice melting, a certain point or several points on the ground wire section are grounded when not melting ice, and the grounding points are disconnected to form an insulated loop when melting ice.

[0108] The overhead ground wire in the ice melting section is fully insulated and grounded at a single point or multiple points. For the convenience of operation personnel, after the ground wire of the grounding tower position is insulated and led down, a grounding switch can be installed for grounding, as Figure 6 shown.

[0109] It should be noted that after the ground wire in the ice melting section is fully insulated, the influence of the induced voltage also needs to be considered when the ground wire is connected to the ice melting power supply device. When not melting ice, the ground wire adopts a multi-point grounding method, and the induced voltage is small and can be ignored; in the past, when the ground wire for ice melting was fully insulated after the conductor was out of service, there was no induced voltage on the ground wire. However, in the present invention, when melting ice, the conductor is not out of service, and the ground wire is fully insulated to form an ice melting loop, and the conductor will continuously generate an induced voltage on the ground wire, which will affect the access and startup of the ice melting power supply. Therefore, as Figure 7 shown, connecting the ground wire induced voltage suppression device in parallel to the ground wire can suppress the induced voltage on the ground wire and achieve the effect of normal ice melting of the ground wire.

[0110] In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiments or examples. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0111] Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for de-icing the ground wire without power outage of the wire, characterized in that, It includes the following steps: S1. Determine the section that needs to be de-iced for the ground wire according to the division of the engineering ice area, the selection of the ground wire type, and the engineering micro-topography and micro-meteorology areas, and determine the scope and length of the ground wire de-icing; S2. Determine the de-icing duration according to the relationship between the ambient temperature, wind speed, ice thickness and de-icing current, and obtain the maximum and minimum values of the ground wire de-icing current; S3. According to the limit value of the de-icing current value, obtain the maximum length Lmax of a single de-icing, and divide the de-icing scope into single or multiple de-icing sections according to Lmax; the longest de-icing section does not exceed twice of Lmax; S4. Select the ground wire de-icing connection method for this section according to the length of the de-icing section and the position of the de-icing power supply access point. The ground wire de-icing connection method includes a series de-icing connection method and a parallel de-icing connection method; Among them, when the length of the de-icing section is not greater than the maximum length Lmax of a single de-icing, this de-icing section adopts the series de-icing connection method. The series de-icing connection method includes a first series de-icing connection method and a second series de-icing connection method; When the de-icing section adopts the first series de-icing connection method, connect the two ground wires to the positive and negative poles of the de-icing power supply respectively at the starting end of the de-icing section, and connect the two ground wires through a series wire at the end of the de-icing section to form a series circuit; When the de-icing section adopts the second series de-icing connection method, connect one of the two ground wires to the positive and negative poles of the de-icing power supply at any point in the de-icing section, cut off the ground wires on both sides of the ground wire where the de-icing power supply is connected, and connect the two ground wires through a series wire at the starting end and the end of the de-icing section respectively to form a series circuit; When the length of the de-icing section is greater than the maximum length Lmax of a single de-icing, this de-icing section adopts the parallel de-icing connection method. Connect the midpoints of the resistances of the two ground wires in the de-icing section to the positive and negative poles of the de-icing power supply respectively, and connect the two ground wires through a series wire at the starting end and the end of the de-icing section respectively to form a parallel circuit; S5. Calculate the required de-icing capacity range and de-icing voltage range for each section according to the selected ground wire de-icing connection method for the de-icing section, and determine the rated current, rated voltage and rated capacity of the de-icing power supply; S6. Install insulators on the ground wire suspension string and tension string, and install insulating drainage wire clamps on the drainage wire to realize the insulation transformation of the ground wire; S7. Install arc horns on the insulators of the ground wire de-icing suspension string and tension string; S8. Perform the ground wire de-icing operation.

2. A live-line ground wire de-icing method for conductors according to claim 1, characterized in that, When the de-icing section adopts the series de-icing connection method, the total resistance of the de-icing section is the sum of the resistance values of the two ground wires in the de-icing section.

3. A method for deicing the ground wire without power outage of a wire, characterized in that, When the de-icing section adopts the parallel de-icing connection method, the total resistance of the de-icing section is half of the sum of the resistance values of the two ground wires in the de-icing section.

4. A live-line ground wire ice melting method for conductors according to claim 3, characterized in that, When the de-icing section adopts the parallel de-icing connection method, perform unilateral de-icing on the de-icing section according to the severity of icing. That is, connect the two ground wires through a series wire at the starting end of the de-icing section, and the two ground wires at the end are not connected, or connect the two ground wires through a series wire at the end of the de-icing section, and the two ground wires at the starting end are not connected.

5. A live-line ground wire de-icing method for a conductor according to any one of claims 1 to 4, characterized in that In S5, when the series ice melting connection mode is adopted in the ice melting section, the ice melting voltage range of this section is IminR~ImaxR, and the ice melting capacity range is Imin 2 R~Imax 2 R. The rated current required for the ice melting power supply is Imax, the rated voltage is ImaxR, and the rated capacity is Imax 2 R; When the parallel ice melting connection mode is adopted in the ice melting section, the ice melting voltage range of this section is IminR~ImaxR, the ice melting capacity range is 2IminR~2ImaxR, the rated current required for the ice melting power supply is 2Imax, the rated voltage is ImaxR, and the rated capacity is 2ImaxR; Among them, Imin is the minimum value of the ground wire ice melting current obtained in S2, Imax is the maximum value of the ground wire ice melting current obtained in S2, and R is the total resistance of the ice melting section.

6. A method for de-icing the ground wire without power outage of a wire, according to any one of claims 1 to 4, characterized in that It also includes: Select the ice melting power supply according to the actual situation on site and the rated current, rated voltage and rated capacity of the ice melting power supply obtained in S5. The ice melting power supply includes a mobile ice melting vehicle, an offline fixed ice melting device, and an ice melting power supply in the substation.

7. A live-line ground wire de-icing method for conductors according to any one of claims 1 to 4, characterized in that It also includes: Install an induced voltage suppression device on the ground wire.

8. A method for de-icing the ground wire without power interruption of a wire, according to any one of claims 1 to 4, characterized in that In S6, after the insulation transformation of the ground wire, at least one point of the ground wire in the ice melting section is grounded when not melting ice, and the grounding point is disconnected to form an insulated circuit when melting ice.

Images