A dc three-loop cross-tower tower head

Abstract

The application provides a DC three-circuit crossing tower head, which is arranged at the top of a tower body and comprises an octagonal tower window, a pair of first cross arms and a pair of second cross arms; the middle part of each first cross arm is provided with a first rod unit which is inclined downward, and the two first rod units are symmetrically arranged; the end part of each first cross arm is provided with a ground wire hanging point; the first rod unit of each first cross arm is provided with a first circuit conductor hanging point; the vertical symmetry axis of the octagonal tower window is provided with second circuit conductor hanging points which are arranged in an up-down distribution; the end part of each second cross arm is provided with a third circuit conductor hanging point; the tower head designs three DC transmission lines into two layers of triangular arrangements, compared with the traditional three DC vertical hanging line mode, the design reduces the height of the crossing tower head through the staggered arrangement of the conductor hanging points, thereby improving the lightning protection performance and stability of the crossing tower.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of power equipment, and particularly relates to a DC three-loop crossing tower head. BACKGROUND

[0002] Cross-region power transmission is an important way to guarantee the load development of regions with less energy distribution. In the process of cross-region power transmission, the current generally adopts a DC three-loop crossing tower to improve the transmission capacity of the line per corridor and the land utilization rate, but the existing DC three-loop crossing tower mostly adopts a drum-type tower, and the tower head generally adopts a traditional three-loop DC vertical wire hanging mode to arrange three layers of wire cross arms and one layer of ground wire cross arm. Considering the electrical distance requirement between the cross arms, the existing drum-type crossing tower head is generally designed to be very high. For example, the tower head structure of the Zhenjiang Wufengshan ±200kV large crossing tower is about 33m long. The lightning protection effect of such a crossing tower head is poor, the material investment is large, the tower head weight is large, and the stability is poor. SUMMARY

[0003] In order to reduce the height of the crossing tower head, improve the lightning protection performance and stability of the crossing tower head, the present application provides a DC three-loop crossing tower head.

[0004] The technical scheme of the present application is as follows:

[0005] A DC three-loop crossing tower head is arranged at the top of a tower body, the DC three-loop includes a first loop, a second loop and a third loop, and comprises an octagonal tower window, a pair of first cross arms symmetrically arranged at the top of the octagonal tower window and upwardly inclined and in the shape of a spread wing, and a pair of second cross arms symmetrically arranged at the two sides of the middle part of the octagonal tower window; the pair of first cross arms are respectively provided with a first rod unit downwardly inclined, and the two first rod units are symmetrically arranged;

[0006] The vertical symmetry axis position of the octagonal tower window is provided with an upper second loop wire suspension point and a lower second loop wire suspension point in an up-down distribution, the two first rod units are respectively provided with a first loop wire suspension point, and the two first loop wire suspension points and the upper second loop wire suspension point are arranged in an inverted triangular shape; the ends of the pair of second cross arms are respectively provided with a third loop wire suspension point, and the lower second loop wire suspension point and the two third loop wire suspension points are arranged in a triangular shape; and the ends of the pair of first cross arms are respectively provided with a ground wire suspension point.

[0007] Further, the horizontal distance between the two ground wire suspension points is greater than the horizontal distance between the two first wire suspension points.

[0008] Further, the horizontal distance between the two ground wire suspension points is greater than the horizontal distance between the two third wire suspension points.

[0009] Further, the octagonal tower window comprises horizontally arranged upper and lower trusses and left and right trusses connecting the upper and lower trusses; the left truss comprises a left upper inclined truss, a left vertical truss and a left lower inclined truss; and the right truss comprises a right upper inclined truss, a right vertical truss and a right lower inclined truss.

[0010] Further, the pair of second cross arms are respectively arranged downwardly inclined.

[0011] Further, the pair of second cross arms are respectively connected with the left and right vertical trusses.

[0012] Further, the upper and lower second circuit conductor suspension points are respectively provided with V-shaped insulators.

[0013] Further, the left and right vertical trusses are connected through inclined materials, the upper second circuit conductor suspension point is arranged at the center of the upper truss, and the lower second circuit conductor suspension point is arranged at the center of the inclined material.

[0014] Further, for the ±200kV voltage level of the DC three-circuit, the horizontal distance between the two ground wire suspension points is not less than 22m, the horizontal distance between the left and right vertical trusses is not less than 10m, the length of the upper truss is not less than 4m, the length of the lower truss is not less than 5m, the vertical distance between the upper and lower trusses is not less than 20m, and the length of the first rod unit is not less than 4m.

[0015] Compared with the prior art, the present application has the following beneficial effects:

[0016] The present application provides a DC three-circuit crossing tower head, which arranges the three-circuit DC transmission lines in an upper and lower two-layer triangular shape, compared with the conventional three-circuit DC vertical hanging line mode, the design reduces the height of the crossing tower head through the staggered arrangement of the conductor suspension points, thereby improving the lightning protection performance of the crossing tower. At the same time, the design also reduces the position of the gravity center of the tower head and the amount of steel material of the tower head, thereby improving the stability of the crossing tower head.

[0017] In the crossing tower head of the present application, the horizontal distance between the two ground wire suspension points is greater than the horizontal distance between the two first conductor suspension points and the horizontal distance between the two ground wire suspension points is greater than the horizontal distance between the two third conductor suspension points, which makes the protection angle of the three-circuit DC line negative, can well reduce the lightning shielding flashover rate, thereby playing a good protection role in lightning protection of the line.

[0018] The ground wire hanging point and the first loop wire hanging point share the first cross arm in the tower head of the crossing tower, so that a compact power transmission line is formed, and the compact power transmission line is matched with the conventional power transmission line, so that the electrical clearance between the tower and the wire is guaranteed, and the operation and maintenance of the three-loop direct current line is facilitated to a great extent.

[0019] The tower window in the tower head of the crossing tower adopts an octagonal design, so that the wire hanging point can be arranged at the central axis of the tower, the height and width of the tower head can be effectively reduced without changing the loop number of the wire, and the stability of the tower head is guaranteed.

[0020] The upper and lower second loop wire hanging points in the tower head of the crossing tower are provided with V-shaped insulators, so that the wire hanging in the tower window is more stable, the wind deviation of the insulator string is effectively inhibited, and the safe operation of the wire in the tower window is important. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 It is a structure schematic diagram of the direct current three-loop crossing tower head.

[0022] Figure 2 It is a structure schematic diagram of the first cross arm.

[0023] Figure 3 It is a structure schematic diagram of the octagonal tower window.

[0024] Figure 4 It is a connection schematic diagram of the second cross arm and the left vertical truss and the right vertical truss.

[0025] Figure 5 It is a position schematic diagram of the ground wire hanging point and the first loop wire hanging point.

[0026] Figure 6 It is a position schematic diagram of the first loop wire hanging point.

[0027] Figure 7 It is a position schematic diagram of the third loop wire hanging point.

[0028] Figure 8 It is a structure schematic diagram of the upper and lower two-layer triangular wire hanging mode.

[0029] Figure 9 It is a schematic diagram of the clearance (tower head clearance circle) of the ±200kV direct current three-loop crossing tower head.

[0030] In the diagram, 1-Left first crossarm; 2-Right first crossarm; 3-Left first member; 4-Right first member; 5-Upper truss; 6-Lower truss; 7-Left upper diagonal truss; 8-Left vertical truss; 9-Left lower diagonal truss; 10-Right upper diagonal truss; 11-Right vertical truss; 12-Right lower diagonal truss; 13-Left second crossarm; 14-Right second crossarm; 15-Diagonal member; Detailed implementation method:

[0031] Example 1:

[0032] This embodiment features a DC three-circuit system spanning the tower head and positioned at the top of the tower body. The DC three-circuit system includes a first circuit, a second circuit, and a third circuit. For example... Figures 1-3 As shown, the tower head includes an octagonal tower window, a pair of first crossarms symmetrically arranged at the top of the octagonal tower window and tilting upwards in a wing-like shape, and a pair of second crossarms symmetrically arranged on both sides of the middle of the octagonal tower window; wherein, the first crossarms include a left first crossarm 1 and a right first crossarm 2; the second crossarms include a left second crossarm 13 and a right second crossarm 14; the left second crossarm 13 and the right second crossarm 14 are respectively tilted downwards. The left first crossarm 1 has a downwardly tilted left first rod unit 3 in the middle, and the right first crossarm 2 has a downwardly tilted right first rod unit 4 in the middle, and the left and right first rod units are symmetrically arranged;

[0033] like Figure 3 As shown, the octagonal tower window adopts a symmetrical structure, including a horizontally arranged upper truss 5 and lower truss 6, as well as a left truss and a right truss connecting the upper truss 5 and lower truss 6; the left truss includes a left upper diagonal truss 7, a left vertical truss 8, and a left lower diagonal truss 9; the right truss includes a right upper diagonal truss 10, a right vertical truss 11, and a right lower diagonal truss 12. Figure 4 As shown, the left second crossarm 13 is connected to the left vertical truss 8, and the right second crossarm 14 is connected to the right vertical truss 11; the specific structural dimensions of the tower window are determined according to the electrical performance of DC transmission lines at each voltage level and the required gap distances for working voltage, switching overvoltage and lightning overvoltage.

[0034] like Figure 5 As shown, the end of the left first crossarm is provided with a ground wire suspension point a1, and the end of the right first crossarm is provided with a ground wire suspension point a2; the left first pole unit is provided with a first circuit conductor suspension point b1, and the right first pole unit is provided with a first circuit conductor suspension point b2; the ground wire suspension point and the first circuit conductor suspension point share the first crossarm, thus forming a compact transmission line. At the same time, the compact transmission line is combined with the conventional transmission line, which not only ensures the electrical clearance between the tower and the conductor, but also greatly facilitates the operation and maintenance of the three-circuit DC line.

[0035] like Figure 6As shown, the vertical symmetry axis of the octagonal tower window is provided with the upper second loop conductor suspension point c1 and the lower second loop conductor suspension point c2 arranged in an up-down manner;

[0036] As shown in the figure, Figure 7 The end of the left second cross arm is provided with the third loop conductor suspension point d1, and the end of the right second cross arm is provided with the third loop conductor suspension point d2.

[0037] As shown in the figure, Figure 8 The first loop conductor suspension point b1, the first loop conductor suspension point b2, and the upper second loop conductor suspension point c1 are arranged in an inverted triangle, and the lower second loop conductor suspension point c2, the third loop conductor suspension point d1, and the third loop conductor suspension point d2 are arranged in an equilateral triangle. Compared with the conventional three-loop direct-current vertical hanging line mode, the three-loop direct-current transmission line is designed to be arranged in an upper and lower triangular shape through the staggered arrangement of the conductor suspension points, thereby reducing the height of the tower head of the crossing tower and improving the lightning protection performance of the crossing tower. At the same time, the gravity center position of the tower head of the crossing tower is low, and the amount of steel used in the tower head is small, thereby making the stability of the tower head of the crossing tower high.

[0038] Embodiment two:

[0039] A further optional design of the embodiment is that the horizontal distance between the two ground wire suspension points is greater than the horizontal distance between the two first conductor suspension points, and the horizontal distance between the two ground wire suspension points is greater than the horizontal distance between the two third conductor suspension points. This design makes the protection angle of the three-loop direct-current line negative, which can well reduce the lightning shielding flashover rate, thereby playing a good protective role in lightning protection of the line.

[0040] Embodiment three:

[0041] A further optional design of the embodiment is that the second loop conductor suspension point of the embodiment is provided with a V-shaped insulator, which makes the conductor suspension in the tower window more stable and can effectively suppress the wind deviation of the insulator string, thereby playing an important role in the safe operation of the conductor in the tower window.

[0042] Embodiment four:

[0043] A further optional design of the embodiment is that, as shown in the figure, Figure 1 The left vertical truss 8 and the right vertical truss 11 of the embodiment are connected through the inclined material 15, and the octagonal tower window is divided into two layers of small tower windows through the inclined material 15. A second loop conductor suspension point is arranged in each layer of small tower windows, and the upper second loop conductor suspension point c1 can be arranged at the center position of the upper truss 5, and the lower second loop conductor suspension point c2 can be arranged at the center position of the inclined material 15.

[0044] Embodiment five:

[0045] The embodiment provides a ±200kV voltage grade DC three-circuit spanning tower head which is arranged at the top of a tower body and comprises an octagonal tower window, a pair of first cross arms which are symmetrically arranged at the top of the octagonal tower window and are upwardly inclined and in the shape of spread wings, and a pair of second cross arms which are symmetrically arranged at the two sides of the middle part of the octagonal tower window; the middle parts of the pair of first cross arms are respectively provided with a first rod unit which is downwardly inclined, and the two first rod units are symmetrically arranged; the first rod units of the pair of first cross arms are respectively provided with a first circuit conductor suspension point; the vertical symmetry axis position of the octagonal tower window is provided with an upper second circuit conductor and a suspension point which are distributed in an up-down mode; the end parts of the pair of second cross arms are respectively provided with a third circuit conductor suspension point; the two first circuit conductor suspension points and the upper second circuit conductor suspension point are arranged in an inverted triangular mode, and the lower second circuit conductor suspension point and the two third circuit conductor suspension points are arranged in a triangular mode. The gap distance analysis of the tower head is as follows:

[0046] After the windage yaw of the insulator string, the DC 50% discharge voltage U of the air gap of the conductor to the tower 50％N Should meet the following requirements:

[0047]

[0048] In the formula: U N is the rated working voltage; K1 and K2 are air density and humidity correction coefficients of the gap discharge voltage under DC voltage; K3 is a safety factor, 1.1-1.15, and in the example, 1.15; σ s is the relative standard deviation of the DC discharge voltage of the air gap, 0.9%.

[0049] In order to ensure the safety of the tower head, the critical flashover gradient of the conductor-tower body DC operating voltage in the embodiment is 400kV / m, and when the corresponding altitude is 0m, K1 is 1, the minimum gap S I1 between the charged body of the power transmission line and the tower component of the tower head adopting the I-type insulator string is 0.59m, and the minimum gap S V1 between the charged body of the power transmission line and the tower component of the tower head adopting the V-type insulator string is 0.64m, and the calculation formulae of S I1 and S V1 are as follows:

[0050]

[0051]

[0052] Considering the altitude correction, when the corresponding altitude is 1000m, K1 is 0.9, and the values of the above S I1 and S V1 are 0.66m and 0.71m respectively. When the corresponding altitude is 500m, K1 is 0.95, and the values of the above SI1 and S V1 are respectively 0.62m and 0.68m.

[0053] After the windage of the I-shaped insulator string, the positive polarity 50% operating impulse discharge voltage U 50％S of the air gap between the conductor and the tower should meet the following requirements:

[0054]

[0055] In the formula, U m is the highest operating voltage, kV; K1', K2' are the air density and humidity correction coefficients of the gap discharge voltage under the operating impulse voltage; K3' is the operating overvoltage multiple; σ s1 is the relative standard deviation of the air gap discharge voltage under the operating voltage, 5%. In this example, the influence of wind speed is considered when calculating the air gap, and the 0.5 times of the maximum wind speed of the line design is taken.

[0056] The positive polarity 50% operating impulse discharge voltage U 50％S of the air gap between the conductor and the tower of the V-shaped insulator string should meet the following requirements:

[0057]

[0058] After the calculated operating impulse discharge voltage U 50％S , the operating air gap S2 can be calculated according to the following formula:

[0059]

[0060] The air gap S I2 corresponding to the I-shaped insulator string is 1.55 meters; the air gap S V2 corresponding to the V-shaped insulator string is 1.76 meters.

[0061] Under the lightning overvoltage working condition, the positive polarity 50% lightning impulse discharge voltage U k50％ of the air gap should match the 50% lightning impulse discharge voltage U j50％ of the insulator string, but it is not necessary to determine the gap according to 100% of U j50％ , only 80% of U j50％ , as shown in the following formula.

[0062] U k50％ = 80%·U j50％

[0063] In the formula, U k50％ and U j50％ are in kV, and their values can be obtained according to the lightning impulse test of the insulator string. In this example, the length of the insulator string is 6.39m.

[0064] After obtaining the air gap positive polarity lightning impulse 50% discharge voltage U k50％ According to the DC air gap 50% lightning impulse characteristic diagram given by the Electric Power Research Institute (lightning impulse test of insulator string), the minimum gap required by the lightning overvoltage is 3.45 m.

[0065] According to the above gap distance requirements and the length requirements of the insulator string, the ±200kV voltage level DC three-circuit crossing tower head gap circle diagram is drawn as shown in Figure 9 The tower head size is calculated as follows: the horizontal distance between the two ground wire suspension points in the tower head is not less than 22 m, the horizontal distance between the left vertical truss and the right vertical truss is not less than 10 m, the length of the upper truss is not less than 4 m, the length of the lower truss is not less than 5 m, the vertical distance between the upper truss and the lower truss is not less than 20 m, and the length of the first rod unit is not less than 4 m.

Claims

1. A DC three circuit cross-over tower head arranged at the top end of a tower body, the DC three circuit comprising a first circuit, a second circuit and a third circuit, characterized in that: The octagonal tower window, a pair of first cross arms symmetrically arranged at the top of the octagonal tower window and upwardly inclined and wing-shaped, and a pair of second cross arms symmetrically arranged at the two sides of the middle part of the octagonal tower window; the pair of first cross arms are respectively provided with a first rod unit downwardly inclined, and the two first rod units are symmetrically arranged; The vertical symmetry axis position of the octagonal tower window is provided with an upper second loop conductor suspension point and a lower second loop conductor suspension point distributed in an up-down manner, the two first rod units are respectively provided with a first loop conductor suspension point, the two first loop conductor suspension points and the upper second loop conductor suspension point are arranged in an inverted triangle, the end parts of the pair of second cross arms are respectively provided with a third loop conductor suspension point, the lower second loop conductor suspension point and the two third loop conductor suspension points are arranged in an equilateral triangle, and the end parts of the pair of first cross arms are respectively provided with a ground wire suspension point; The horizontal distance between the two ground wire suspension points is greater than the horizontal distance between the two first conductor suspension points; The horizontal distance between the two ground wire suspension points is greater than the horizontal distance between the two third conductor suspension points; The octagonal tower window comprises upper and lower horizontal trusses and left and right side trusses connecting the upper and lower trusses; the left side truss comprises a left upper inclined truss, a left vertical truss and a left lower inclined truss; the right side truss comprises a right upper inclined truss, a right vertical truss and a right lower inclined truss; The pair of second cross arms are respectively downwardly inclined; The pair of second cross arms are respectively connected with the left vertical truss and the right vertical truss; The upper and lower second loop conductor suspension points are respectively provided with V-shaped insulators; The left and right vertical trusses are connected through inclined materials, the upper second loop conductor suspension point is arranged at the center position of the upper truss, and the lower second loop conductor suspension point is arranged at the center position of the inclined material.

2. The DC three-loop cross-tower terminal of claim 1, characterized in that: For a ±200kV voltage grade direct current three-loop, the horizontal distance between the two ground wire suspension points is not less than 22m, the horizontal distance between the left vertical truss and the right vertical truss is not less than 10m, the length of the upper truss is not less than 4m, the length of the lower truss is not less than 5m, the vertical distance between the upper truss and the lower truss is not less than 20m, and the length of the first rod unit is not less than 4m.

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