CN203243007U - Lightning protection system of extra-high voltage AC double-circuit lines - Google Patents

Abstract

The utility model discloses a lightning protection system for a UHV AC double-circuit line, which comprises a UHV AC double-circuit tension tower (10), an UHV AC double-circuit straight line tower (1), and an OPGW optical cable or a ground wire ( 6), different arrangements and combinations of V-shaped suspension strings (7), suspension strings (8) of OPGW optical cables or lightning conductors, and strain-resistant strings (9) of OPGW optical cables and lightning conductors, to determine the best UHV AC double-circuit line protection Lightning model, the upper crossarm (2) and the middle crossarm (3) of the UHV AC double-circuit linear tower (1) are side-mounted with OPGW optical cables or lightning conductors (6); 2. The upper crossarm (2), the middle crossarm Carry (3), lower floor cross-arm (4) all hang V-shaped hanging string (7) and many split wires (5) under, the utility model is effectively anti-winding lightning, lightning protection protection effect is big.

Description

A Lightning Protection System for UHV AC Double Circuit Line

Technical field:

The utility model relates to a lightning protection system for an ultra-high voltage AC double-circuit line, which belongs to the field of design, operation and maintenance of overhead transmission lines in power systems.

Background technique:

At present, it has been recorded in public literature that shielding is the main reason for lightning tripping of UHV lines. It is believed that special attention should be paid to the shielding problem of mountainous lines with large ground inclination angles. It is suggested to reduce the protection angle of the ground wire to reduce the shielding trip rate. It is proposed that the ground protrusions within 38m on both sides of the line will cause lightning strikes. The published literature puts forward the shielding analysis model for pilot development, and the calculation results are basically consistent with the actual operation of the 1000kV double-circuit line in Japan; while the results obtained by using the electrical geometric strike distance method (referred to as EGM) are just the opposite. From 1998 to 2004 (6 years of operation), there were 81 lightning shielding faults on 1100kV double-circuit lines in Japan, including 79 negative lightning strikes, 34 lightning shielding failures, 27 lightning shielding failures on the upper, middle and lower phase conductors, respectively 18 times. From 1993 to September 2007, a 1100kV double-circuit line in Japan had 68 trip faults, 67 of which were lightning trips. Although the negative protection angle was used for lightning protection, the main reason for the lightning trips was still It is shielding; the area where the east-west line of the 1100kV double-circuit line in Japan is located has 25 annual thunderstorm days, and the trip rate (100km.a) is as high as 0.9 times during the operation at 500kV step-down. Obviously, the two OPGW optical cables or lightning conductors (commonly known as ground wires) of the UHV 1100kV line cannot effectively protect against lightning, and lightning protection with multiple lightning conductors is the research and development direction.

Patent Document 1 (Lightning protection system for UHV AC double-circuit linear tower, patent number ZL201220237569.6) OPGW optical cable or lightning conductor is added to the middle and lower cross arms, and V-shaped suspension strings are hung on the middle cross arm. The static protection angle of the lower phase conductor is low in cost and effectively reduces the electromagnetic field intensity to the ground; the disadvantage is that the OPGW optical cable or lightning conductor of the lower crossarm has little effect on the lightning protection of the upper phase conductor. The actual operation of UHV double-circuit lines in Japan is that the protection angle of the upper-phase conductor is the smallest, but the number of lightning strikes is still the largest, followed by the middle-phase conductor. Therefore, it is very important to strengthen the lightning protection of the upper and middle phase conductors.

Patent Document 2 (A method of improving the lightning protection capability of ultra-high voltage transmission lines, patent number ZL200910061120.1) The upper and middle cross arms are hung with OPGW optical cables or lightning conductors, and the upper, middle and lower cross arms are The poles are all hung with I-type suspension strings. Although the OPGW optical cable or lightning conductor of the middle cross-arm strengthens the anti-circling lightning of the upper and middle phase conductors; The safety distance, but the central safety distance in the gear cannot meet the requirements of the design specifications, and there is no obvious change to the protection angle of the lower phase conductor.

Utility model content:

The purpose of the utility model is to overcome the deficiencies of the above-mentioned prior art and provide a lightning protection system for UHV AC double-circuit lines with effective protection against lightning strikes and great protection against lightning.

The purpose of this utility model can be achieved through the following measures: a lightning protection system for UHV AC double-circuit lines, which includes UHV AC double-circuit tension towers, UHV AC double-circuit straight towers, UHV AC double-circuit straight lines The towers are respectively equipped with the upper cross arm of the straight tower, the middle cross arm of the straight tower, and the lower cross arm of the straight tower. It is characterized in that the upper cross arm of the straight tower is symmetrically provided with V-shaped suspension strings, and the V-shaped suspension strings are connected with multiple split conductors. There is at least one suspension string on both sides of the upper cross arm of the linear tower; V-shaped suspension strings are symmetrically arranged under the middle cross arm of the linear tower. At least one suspension string is provided on both sides of the middle cross arm of the linear tower, and at least one tension string is provided on both sides of the middle cross arm of the straight tower adjacent to the strain tower; the lower cross arm of the straight tower There are V-shaped hanging strings symmetrically arranged under the load, and the V-shaped hanging strings are connected to multiple split conductors;

The UHV AC double-circuit tension towers are equipped with ground wire cross arms, tension tower upper layer cross arms, tension tower middle layer cross arms, and tension tower lower layer cross arms. A tension string, the two sides of the upper cross arm of the tension tower are respectively equipped with multi-split conductors, the two sides of the middle cross arm of the tension tower are respectively equipped with multi-split conductors, and the two sides of the lower cross arm of the tension tower are respectively equipped with multi-split wire;

The tension string of the ground cross arm is connected to one end of an OPGW optical cable or lightning protection wire, and the other end of the OPGW optical cable or lightning protection wire is connected to the suspension string of the upper cross arm of the straight tower of the straight tower adjacent to the tension tower; The tension string of the cross arm of the straight tower of the straight tower adjacent to the tower is connected to one end of an OPGW optical cable or lightning protection wire, and the other end of the OPGW optical cable or lightning protection wire is connected to the middle cross arm of the straight tower of the straight tower adjacent to the straight tower The suspension string of the cross arm of the straight tower not adjacent to the strain tower; the OPGW optical cable or lightning protection line is connected between the suspension string of the middle cross arm of the straight tower of the straight tower. .

Compared with the prior art, the utility model can produce the following positive effects: the utility model has no mature lightning shielding theory so far; The arrangement and combination of OPGW optical cable and lightning protection line tension string determine the best lightning protection system for UHV AC double-circuit lines: OPGW optical cables are hung on the upper and middle cross-arms of UHV AC double-circuit straight line towers Or lightning conductors; hang lightning conductors outside the middle cross arm to reduce the static protection angle of the middle and lower phase conductors, and more importantly, combine with the lightning conductors outside the upper crossarm to strengthen the upper phase conductors that are most vulnerable to lightning strikes lightning protection. 2. The upper cross-arm, middle cross-arm, and lower cross-arm are hung with V-shaped suspension strings and multi-split wires to minimize the lightning protection angle and ensure that the theoretical value of the shielding rate is zero. The larger the span, the greater the minimum safe distance between the central conductor and the ground wire in the stall; for this reason, a V-shaped suspension string is hung on the upper cross arm, so that the multi-split conductors move closer to the tower body, and at the same time stay away from the outer lightning protection wire of the middle cross arm. Make the minimum distance between the upper phase conductor and the lightning conductor in the center of the file meet the requirements of the design specification for the center of the file. Unit: m

file distance 300 400 500 600 700 The minimum distance between the central wire and the ground wire in the file (design specification) 8.1 9.6 11.1 12.6 14.1

The middle cross-arm and the lower cross-arm are hung with V-shaped suspension strings, so that the static protection angle of the outer lightning protection wire of the middle cross-arm to the multi-split conductors on the lower cross-arm is about -20° or more, realizing the compact arrangement of UHV AC double-circuit lines, One is to minimize the lightning protection angle and reduce the shielding rate. The second is to compress the width of the line corridor to save land and civil compensation.

The cross-arm structure on the straight tower adjacent to the strain tower can be hung with tension strings, but the OPGW optical cable or lightning protection wire is not hung in the gear of the straight tower adjacent to the strain tower, so as to cooperate with the strain tower.

After the above design, the project cost will increase roughly by 3 to 4%. If the factors of reducing the line corridor width (approximately reducing by more than 15m), saving land and civil compensation through the V-shaped string compact arrangement are considered, the increased cost is roughly the same as the reduced cost On the contrary, assuming that the lightning shielding tripping rate of UHV AC double-circuit lines is 0.15 times/100km·year, the increased cost of lightning protection is less than the direct economic loss of lightning power outage within the design period (50 years), far less than the comprehensive loss (including direct losses and consequential losses). The following is the economic benefit analysis of the lightning protection system of the UHV AC double-circuit line of the present invention:

The natural power transmitted by UHV AC 1000kV single-circuit line is 4000MW. Assuming that the average recovery time of one lightning strike outage is 6 hours per time (considered according to the average recovery time of lightning strike and power outage for 110-500kV lines), 24 million kilowatt-hours of electric energy will be lost per circuit. The average electricity price is 0.35 yuan/kWh, and the comprehensive loss (including direct loss and indirect loss) caused by each kilowatt-hour of electricity is 25 times the average electricity price, so the direct loss of power outage is 0.084 billion yuan/time, and the comprehensive loss is 210 million yuan/time times; although the towers of the UHV AC double-circuit lines are higher than the 500kV towers (the average lightning tripping rate of 500kV AC lines in China is 0.17 times/100km·year, and the average lightning tripping rate of ± 500kV DC lines is 1.42 times/100km·year), Assume that the lightning tripping rate of UHV AC double-circuit lines is 0.15 times/100km per year (the actual lightning shielding tripping rate of UHV AC double-circuit lines in Japan is greater than this index), if the path length is 300km, there will be 22 times of lightning tripping in 50 years, and there will be a power outage The direct loss was 185 million yuan, and the comprehensive loss was 4.625 billion yuan. The impact of lightning tripping on the stability of the power grid and system shocks were not taken into account.

Assuming that the UHV AC double-circuit line has a length of 300km and an average span of 400m, compared with the suspension string, the material cost of 6 more composite insulators due to the V-shaped string is: 6 x 300km/0.4km x 7,000 yuan/piece = 0.32 billion yuan; the material cost of adding 2 LBGJ-240-20AC type lightning protection lines in the cross-arm is: 2 lines × 1.6t/km × 300km × 13,000 yuan/t ≈ 0.13 billion yuan, according to the literature [Xiao Hongwei. Transmission lines Analysis of the relationship between tower design load and tower weight [J]. Electric Power Construction, 2006, 27(9): 4-6.] Comparing the tower weight calculation formula (11), the tower weight of the straight tower will increase by 3 to 5% on average About 7.5t/base is added according to the upper limit, and the material cost is: 7.5t/base×300km/0.4km×0.8 million yuan/t=0.45 billion yuan; the total material cost is 0.9 billion yuan, and the cost of the project body is about the material cost 1.6 times of that, an increase of about 144 million yuan; obviously, the existing lightning protection system is less than the direct loss of lightning strike power outage within 50 years of two lightning protection lines, far less than the comprehensive loss. The utility model adds 2 lightning protection wires and V-shaped strings for the upper and lower phases, and the unit static investment increases by 144 million yuan/300km=480,000 yuan/km; the total length of the Anhui-East Electricity Transmission Project in my country is 656km, equivalent to a unit static investment of 0.14 100 million yuan/km; obviously, the cost of adding two ground wires and using V-shaped strings for the upper, middle and lower phases accounts for about 3-4% of the static investment of the line unit; if considering the compact arrangement of V-shaped strings to Reduce the line corridor width (roughly reduced by more than 15m) and save land, the increased cost is basically equal to the reduced cost. There is no experience in the operation of UHV AC double-circuit lines in my country, and adding multiple lightning protection lines with conservative lightning protection design concepts is the research and design direction of line lightning protection.

Description of drawings:

Fig. 1 is the structural representation of the utility model;

Fig. 2 is the structural representation of the linear tower not adjacent to the strain tower of Fig. 1;

Fig. 3 is the structural representation of the linear tower adjacent to the strain tower of Fig. 1;

Fig. 4 is a schematic structural diagram of the strain tower in Fig. 1 .

The specific embodiment: below in conjunction with accompanying drawing, the best embodiment of the present utility model is described in detail:

Embodiment: A lightning protection system for UHV AC double-circuit lines (see Figures 1-4), which includes UHV AC double-circuit tension tower 10, UHV AC double-circuit linear tower 1, and UHV AC double-circuit tower 1. The linear tower 1 is respectively provided with the upper cross arm 2 of the linear tower, the middle cross arm 3 of the linear tower, and the lower cross arm 4 of the linear tower. Connect multi-split conductors 5, at least one suspension string 8 is provided on both sides of the upper cross arm 2 of the linear tower; V-shaped suspension strings 7 are symmetrically arranged under the cross arm 3 of the straight tower middle layer, and the V-shaped suspension strings 7 are connected to multi-split conductors 5. At least one suspension string 8 is provided on both sides of the straight tower middle cross arm 3 of the straight tower 1 not adjacent to the strain tower 10, and the straight tower middle cross arm 3 of the straight tower 1 adjacent to the strain tower 10 Both sides of the pole 3 are respectively provided with at least one tension string 9; the lower horizontal arm 4 of the straight tower is symmetrically provided with V-shaped suspension strings 7, and the V-shaped suspension strings 7 are connected to multi-split conductors 5.

UHV AC double-circuit tension towers 10 are equipped with ground crossarms 11, upper crossarms of tension towers 2', middle crossarms of tension towers 3', lower crossarms of tension towers 4', and ground crossarms Both sides of the pole 11 are respectively provided with at least one tension string 9, the two sides of the upper cross arm 2' of the tension tower are respectively provided with multi-split conductors 5, and the two sides of the middle cross arm 3' of the tension tower are respectively provided with multiple wires. The split conductors 5 are respectively provided with multi-split conductors 5 on both sides of the lower cross arm 4' of the tension tower.

The tension string 9 of the ground wire cross arm 11 is connected to one end of an OPGW optical cable or lightning protection wire 6, and the other end of the OPGW optical cable or lightning protection wire 6 is connected to the upper layer cross arm 2 of the linear tower 1 adjacent to the strain tower 10 Suspended string 8; The tension string 9 of the straight tower middle layer cross arm 3 of the straight tower 1 adjacent to the strain tower 10 is connected to one end of an OPGW optical cable or lightning conductor 6, and the other end of the OPGW optical cable or lightning conductor 6 is connected to The hanging string 8 of the straight tower middle cross arm 3 of the straight tower 1 adjacent to the straight tower 1; the hanging string 8 of the straight tower middle cross arm 3 of the straight tower 1 not adjacent to the strain tower 10 is connected to the OPGW Optical cable or lightning conductor 6.

Claims (1)

1. the lightning-protection system of an extra-high-voltage alternating current double-circuit line, it comprises two strain tower (10), the two tangent towers (1) that return of extra-high-voltage alternating current of returning of extra-high-voltage alternating current, two the returning on the tangent tower (1) of extra-high-voltage alternating current is provided with tangent tower upper strata cross-arm (2), tangent tower middle level cross-arm (3), tangent tower lower floor cross-arm (4) respectively, it is characterized in that being arranged with under the tangent tower upper strata cross-arm (2) V-type suspension string (7), V-type suspension string (7) connects multiple fission conductor (5), and the both sides of tangent tower upper strata cross-arm (2) respectively are provided with at least one suspension string (8); Be arranged with V-type suspension string (7) under the tangent tower middle level cross-arm (3), V-type suspension string (7) connects multiple fission conductor (5), respectively be provided with at least one suspension string (8) with the both sides of the tangent tower middle level cross-arm (3) of the non-conterminous tangent tower of strain tower (10) (1), the both sides of the tangent tower middle level cross-arm (3) of the tangent tower (1) adjacent with strain tower (10) respectively are provided with at least one strain insulator-string (9); Be arranged with V-type suspension string (7) under the tangent tower lower floor cross-arm (4), V-type suspension string (7) connects multiple fission conductor (5);

Two the returning on the strain tower (10) of extra-high-voltage alternating current is provided with ground wire cross-arm (11), strain tower upper strata cross-arm (2 '), strain tower middle level cross-arm (3 '), strain tower lower floor cross-arm (4 ') respectively, the both sides of ground wire cross-arm (11) respectively are provided with at least one strain insulator-string (9), the both sides of strain tower upper strata cross-arm (2 ') are respectively equipped with multiple fission conductor (5), the both sides of strain tower middle level cross-arm (3 ') are respectively equipped with multiple fission conductor (5), and the both sides of strain tower lower floor cross-arm (4 ') are respectively equipped with multiple fission conductor (5);

The strain insulator-string (9) of ground wire cross-arm (11) connects an end of an OPGW optical cable or lightning conducter (6), and the other end of this OPGW optical cable or lightning conducter (6) connects the suspension string (8) of the tangent tower upper strata cross-arm (2) of the tangent tower (1) adjacent with strain tower (10); The strain insulator-string (9) of the tangent tower middle level cross-arm (3) of the tangent tower (1) adjacent with strain tower (10) is connected an end of an OPGW optical cable or lightning conducter (6), and the other end of this OPGW optical cable or lightning conducter (6) connects the suspension string (8) of the tangent tower middle level cross-arm (3) of the tangent tower (1) adjacent with this tangent tower (1); Be connected OPGW optical cable or lightning conducter (6) between the suspension string (8) of the tangent tower middle level cross-arm (3) of the non-conterminous tangent tower of strain tower (10) (1).

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