CN102545126A - Same-tower four-loop power transmission line configured with differentiation insulators - Google Patents

Abstract

The invention relates to a four-circuit power transmission line on the same tower equipped with differentiated insulators, and belongs to the technical field of lightning protection for power system transmission lines. It includes the first, second, third and fourth four-circuit lines and three insulators with different insulation strengths: the first insulator, the second insulator and the third insulator. The first insulator is erected on each phase conductor of the first circuit. A weak insulation circuit is formed; the second insulator is erected on each phase conductor of the second circuit, and the third insulator is erected on each phase conductor of the third and fourth circuits to form a strong insulation circuit. Using the differentiated insulation method proposed by the invention can effectively reduce the simultaneous tripping rate of double-circuit and multi-circuit lines at a lower cost without sacrificing the total tripping rate and the single-circuit tripping rate of weak insulation circuits.

Description

A four-circuit transmission line on the same tower equipped with differentiated insulators

technical field

The invention relates to a four-circuit power transmission line on the same tower equipped with differentiated insulators, and belongs to the technical field of lightning protection for power system transmission lines.

Background technique

Lightning strike is an important cause of tripping of transmission lines. Statistics from CIGRE in 12 countries show that lightning accidents on 275-500kV transmission lines account for 60% of the total accidents. The number of trips caused by lightning strikes in Russian 1150kV transmission lines accounted for 84.2% of the total trips. More than 50% of power system failures in our country are caused by lightning strikes.

With the sustained and rapid economic development, land resources are becoming more and more scarce, and transmission line corridors are becoming increasingly tense. Under this background, multi-circuit lines on the same tower have been used more and more in my country. The use can greatly alleviate the problem of tension in the corridor of transmission lines, but there are the following problems in its application: the height of the towers of the lines paralleled on the same pole is high, which increases the attraction to lightning, so the lightning strike accident will be more serious; when the line is struck by lightning, It is possible to simultaneously trip multiple circuits of multi-circuit lines on the same pole, but from the experience of foreign countries, the simultaneous lightning tripping of multiple single circuits is much smaller than that of multi-circuit lines on the same pole.

When multiple lines on the same pole are struck by lightning, the simultaneous tripping rate of multiple circuits is high, which has a greater impact on the system, especially for systems of 500kV and above. It is of great significance to improve the lightning protection performance of the line to increase the simultaneous tripping rate during lightning strikes.

As for the research on lightning protection of multi-circuit lines on the same tower, as early as the 1960s, M. Kawai et al. carried out a lot of research work on this. Through research, M. Kawai proposed the use of unbalanced insulation measures to reduce the two-circuit simultaneous tripping rate of double-circuit lines on the same tower. The unbalanced insulation method proposed by M.Kawai is implemented by reducing the insulation level of one circuit of the double circuit and increasing the insulation level of the other circuit. The actual operation results show that although this unbalanced insulation method can effectively suppress the double-circuit simultaneous tripping rate, it will increase the total tripping rate.

For the lightning protection of multi-circuit lines on the same tower, Japan once adopted unbalanced insulation, trying to use weakly insulated circuit wires to flashover first and then strengthen the shielding effect of other circuits, so as to achieve the purpose of reducing multiple simultaneous trips. The trip rate increases too much, and the effect of reducing the double-circuit trip rate is not obvious.

However, M. Kawai's research results and Japan's operating experience cannot be simply attributed to the use of unbalanced insulation. In fact, they have something to do with lowering the insulation level of one of them too low. For example, Japan reduces the insulation level of one circuit to 80% or 72% of the insulation level of the other circuit, and some even drop to 61.5%. In Japan's unbalanced double-circuit 500kV lines on the same pole, the insulation level of the low-insulation primary circuit is only 61% of the high-insulation primary circuit, and 75% of the standard insulation level, and the insulation level of the high-insulation primary circuit is also It is only equivalent to the normal insulation level of 23 pieces of XP-300 in my country. Therefore, after Japan's double-circuit lines on the same pole adopt unbalanced insulation, the total trip rate must be too high.

Contents of the invention

The purpose of the present invention is to propose a four-circuit power transmission line on the same tower equipped with differentiated insulators, which overcomes that the existing differential insulation configuration method will reduce the double-circuit and multi-circuit simultaneous trip rate while reducing the total trip rate and single-circuit trip rate. The problem of rising rates. Aiming at the problems existing in the existing unbalanced insulation method, the insulator configuration method of the unbalanced high insulation method is specially proposed. While increasing the insulation distance of the high insulation strength circuit, it does not reduce the insulation distance of the ground insulation strength circuit, so as to reduce the The purpose of double-circuit and multi-circuit simultaneous trip rate without increasing the total trip rate.

The invention proposes a four-circuit power transmission line on the same tower equipped with differentiated insulators. The power transmission line is a four-circuit power transmission line on the same tower. Insulator, six third insulators, support frame, phase A wire of the first transmission line, phase B wire of the first transmission line, phase C wire of the first transmission line, phase A wire of the second transmission line , B-phase wire of the second transmission line, C-phase wire of the second transmission line, A-phase wire of the third transmission line, B-phase wire of the third transmission line, C-phase wire of the third transmission line , the A-phase wire of the fourth power transmission line, the B-phase wire of the fourth power transmission line, the C-phase wire of the fourth power transmission line; the A-phase wire of the first power transmission line, the first power transmission line The B-phase conductor and the C-phase conductor of the first circuit transmission line are erected on the upper part of one side of the support frame; the three first insulators are respectively erected on the A-phase conductor of the first circuit transmission line, the B-phase conductor of the first circuit transmission line, A weak insulation loop is formed on the C-phase conductor of the first circuit transmission line; the A-phase conductor of the second circuit transmission line, the B-phase conductor of the second circuit transmission line and the C-phase conductor of the second circuit transmission line are erected on the The upper part of the other side of the support frame; three second insulators are erected on the A-phase conductor of the second power transmission line, the B-phase conductor of the second power transmission line, and the C-phase conductor of the second power transmission line; The A-phase conductor of the third circuit, the B-phase conductor of the third circuit and the C-phase conductor of the third circuit are erected on the lower part of one side of the support frame; the A-phase conductor of the fourth circuit 1. The B-phase wire of the fourth transmission line and the C-phase wire of the fourth transmission line are erected on the lower part of the other side of the support frame; the six third insulators are respectively erected on the A-phase wire of the third transmission line , B-phase wire of the third transmission line, C-phase wire of the third transmission line, A-phase wire of the fourth transmission line, B-phase wire of the fourth transmission line and C-phase wire of the fourth transmission line above, forming a strong insulation circuit; the tower ground wire is erected on the top of the transmission tower; the tower grounding resistor is placed at the bottom of the transmission tower and connected to the ground.

The advantages of the same-tower four-circuit transmission line configured with differentiated insulators proposed by the present invention are:

1. The four-circuit power transmission line on the same tower equipped with differentiated insulators proposed by the present invention, while enhancing the insulation level of the strong insulation circuit, slightly strengthens the insulation level of the weak insulation circuit. This method can reduce double-circuit and multiple-circuit At the same time trip rate, neither increase the total trip rate of the line, nor increase the single-circuit trip rate of any circuit.

2. In the transmission line of the present invention, a method of using mixed insulators is proposed to achieve the effect of differential insulation. Different types of insulators have different breakdown voltages and insulation levels. In areas where there is no special requirement for insulator types, the purpose of differentiated insulation can be achieved by using mixed insulators, which can reduce the double-circuit and multi-circuit simultaneous tripping rate and reduce costs.

3. The transmission line of the present invention proposes a method of achieving differentiated insulation effects by installing an arc striking angle. The arc striking angle is equivalent to a short parallel gap for insulators, and this parallel gap weakens the insulation level of the circuit. At the same time, it can protect the insulator when struck by lightning. This differential insulation method can not only reduce the double-circuit and multi-circuit simultaneous tripping rate of the line, but also avoid damage to the insulators caused by excessive lightning strikes on weak insulation circuits.

Description of drawings

Fig. 1 is a schematic structural diagram of a four-circuit transmission line on the same tower equipped with differentiated insulators proposed by the present invention.

Fig. 2 is a schematic diagram of the present invention implemented in 220kV double-circuit and 500kV double-circuit four-circuit line towers on the same tower.

Fig. 3 is a schematic diagram of the present invention implemented in a 500kV four-circuit line tower on the same tower.

Fig. 4 is a schematic diagram of the present invention implemented in a double-circuit line tower on the same tower.

In Figure 1-Figure 4, 1 is the tower ground wire; 2 is the first insulator; 3 is the second insulator, 4 is the A-phase conductor of the first circuit transmission line, 5 is the B-phase conductor of the first circuit line, and 6 is the second insulator The C-phase wire of the first circuit transmission line; the corresponding three-phase wire A, B, and C of the second circuit; 7 is the tower support frame; 8 is the tower grounding resistance; 9 is the A of the third circuit transmission line Phase wire, 10 is the B-phase wire of the third circuit transmission line, and 11 is the C-phase wire of the third circuit transmission line; corresponding to it is the A, B, C three-phase wire of the fourth circuit; 12 is the first Three insulators.

Detailed ways

The structure of the same-tower four-circuit transmission line equipped with differentiated insulators proposed by the present invention is shown in Figure 1, including: tower ground wire 1, three first insulators 2, three second insulators 3, six third insulators Insulator 4, support frame 7, A-phase conductor 4 of the first circuit transmission line, B-phase conductor 5 of the first circuit transmission line, C-phase conductor 6 of the first circuit transmission line, A-phase conductor of the second circuit transmission line, Phase B wire of the second power transmission line, phase C wire of the second power transmission line, phase A wire 9 of the third power transmission line, phase B wire 10 of the third power transmission line, phase C of the third power transmission line Conductor 11, the A-phase conductor of the fourth circuit transmission line, the B-phase conductor of the fourth circuit transmission line, and the C-phase conductor of the fourth circuit transmission line. The A-phase wire of the first transmission line, the B-phase wire of the first transmission line and the C-phase wire of the first transmission line are erected on the upper part of one side of the support frame; the three first insulators are respectively erected on the first transmission line A weak insulation loop is formed on the A-phase conductor of the line, the B-phase conductor of the first circuit transmission line, and the C-phase conductor of the first circuit transmission line. The A-phase wire of the second transmission line, the B-phase wire of the second transmission line and the C-phase wire of the second transmission line are erected on the upper part of the other side of the support frame; three second insulators are respectively erected on the second On the A-phase wire of the transmission line, the B-phase wire of the second transmission line, and the C-phase wire of the second transmission line. The A-phase conductor of the third circuit, the B-phase conductor of the third circuit and the C-phase conductor of the third circuit are erected on the lower part of one side of the support frame; the A-phase conductor of the fourth circuit 1. The B-phase wire of the fourth power transmission line and the C-phase wire of the fourth power transmission line are erected on the lower part of the other side of the supporting frame. The six third insulators 12 are erected on the A-phase conductor of the third transmission line, the B-phase conductor of the third transmission line, the C-phase conductor of the third transmission line, the A-phase conductor of the fourth transmission line, and the third transmission line. A strong insulation circuit is formed on the B-phase wire of the four-circuit transmission line and the C-phase wire of the fourth-circuit transmission line. The tower ground wire 1 is erected on the top of the transmission tower. The tower grounding resistor 8 is placed at the bottom of the transmission tower and connected to the ground.

The working principle of the present invention is to use the primary circuit which is most prone to counter-flashover as a weak insulation circuit, and its insulation level remains unchanged or slightly strengthened; the insulation level of other circuits is strengthened as a strong insulation circuit. The difference in insulation level is used to make the weak insulation circuit flashover first, and play a certain shielding effect on the strong insulation circuit, so as to open the lightning withstand level of the strong insulation circuit and the weak insulation circuit, and reduce the double-circuit and multiple-circuit simultaneous trip rate.

The simultaneous tripping of multi-circuit lines on the same tower with different voltage levels is different. Operation experience shows that the lower the voltage level, the more serious the phenomenon of simultaneous tripping of double-circuit transmission lines and multi-circuit transmission lines. The four-circuit power transmission line on the same tower configured with differentiated insulators proposed by the present invention includes a differentiated insulation configuration method for double-circuit and four-circuit lines on the same tower with different voltage levels. The invention mainly relates to the differentiated insulation configuration of 500kV and below double-circuit and four-circuit lines on the same tower.

The four-circuit power transmission line on the same tower configured with differentiated insulators in the present invention can have the following different forms:

(1) 110kV four-circuit line on the same tower:

The general structure of the 110kV four-circuit line tower on the same tower is a total of six layers of cross-arms. The conductors of each circuit are arranged vertically. 1.

The characteristic of the 110kV four-circuit line on the same tower is that the height difference between the upper three-story cross-arm and the lower three-story cross-arm is relatively small. Back to the situation of flashover at the same time. When configuring the differential insulation scheme for 110kV four-circuit lines on the same tower, except for the one with weak insulation, the insulation levels of the other circuits should be strengthened more evenly. Therefore, for the 110kV four-circuit line on the same tower, the differentiated insulation scheme proposed by the present invention is that the insulation level of the left side of the upper three-layer cross-arm remains unchanged, and the insulation level of the right side of the upper three-layer cross-arm and the lower three-layer insulators increase by 20%. It is shown in Fig. 1 that the insulation strength of the first insulator remains unchanged in the original design, and the insulation strength of the second and third insulators increases by 20%. Under this configuration, the double-circuit simultaneous tripping rate and the three-circuit simultaneous tripping rate can be reduced to about 30% of the original.

(2) 110kV double-circuit and 220kV double-circuit four-circuit lines on the same tower:

The general arrangement of conductors for 110kV double-circuit and 220kV double-circuit four-circuit lines on the same tower is that two circuits of 220kV lines are arranged on the upper three-story cross-arm, and two circuits of 110kV lines are arranged on the lower three-story cross-arm. The three-phase conductors are still arranged vertically, as shown in Figure 1, the first and second loops are 220kV loops, and the third and fourth loops are 110kV loops. Although the insulation strength of the 220kV line is relatively high, because it is arranged on the upper layer of the tower and is close to the lightning strike point, the 220kV line is still the first to flashover when the lightning strikes, so the first circuit is still regarded as a weak insulation circuit. For the 110kV double-circuit and 220kV double-circuit four-circuit lines on the same tower, the differential insulation scheme proposed by the present invention is to increase the insulation level of the 110kV line by 30%, and increase the insulation level of the 220kV line on the right side of the upper three-layer cross arm by 6.7%, that is, the first insulator The insulation strength of the original design is kept unchanged, the insulation strength of the second insulator is increased by 6.7% on the original basis, and the third insulator 12 is increased by 30% on the original basis. Under this differentiated insulation configuration scheme, the double-circuit simultaneous tripping rate can be reduced to 30% of the original, and the three-circuit simultaneous tripping rate can be reduced to about 60% of the original.

(3) 220kV four-circuit line on the same tower:

The tower structure of the 220kV four-circuit line on the same tower is the same as that of the 110kV four-circuit line on the same tower, as shown in Figure 1. The difference is that the lightning withstand level of each line of the 220kV four-circuit line on the same tower is quite different, and the double-circuit and multi-circuit simultaneous flashover phenomenon is not as serious as that of the 110kV. For the 220kV four-circuit line on the same tower, the differentiated insulation scheme proposed by the present invention is to increase the insulation strength of the insulators on the lower cross-arm by 13%, increase the insulation strength of the right cross-arm insulators on the upper three layers by 20%, and increase the insulation strength of the left cross-arm insulators on the upper three layers. The dielectric strength increases by 6.7%, that is, the first insulator increases the dielectric strength by 6.7% on the original basis, the second insulator increases the dielectric strength by 20% on the original basis, and the third insulator increases the dielectric strength by 13% on the original basis. In the present invention, all differentiated insulation schemes use the primary circuit on the left side of the upper layer as a weak insulation circuit.

In the 220kV four-circuit line on the same tower, when the insulation strength is increased on the right side of the upper three floors (the second ground insulator), the right insulator is more difficult to flashover, so no matter whether the lightning hits the left or right side of the tower, it is the left insulator The flashover is equivalent to transferring the original flashover from the right side to the left side, resulting in an increase in the tripping rate of the left line. Therefore, this scheme slightly increases the insulation level of the weak insulation circuit (the first insulator on the left side of the upper layer) while increasing the insulation strength of the strong insulation circuit. Single return trip rate.

(4) 220kV double-circuit and 500kV double-circuit four-circuit lines on the same tower:

The structure of the 220kV double circuit and 500kV double circuit four circuit lines on the same tower is as follows. ; The 500kV two-circuit line is arranged on the bottom two-layer cross arm, the two-circuit lines are arranged left and right, and the three-phase conductors of each circuit are arranged in a triangle, as shown in Figure 2.

When this kind of line is struck by lightning, the 220kV line will flashover first, and at the same time, it will shield the 500kV line. Since the 500kV line is located on the lower layer of the tower, it is far away from the lightning strike point, and its insulation level is relatively high, so the lightning withstand level is relatively high, and the simultaneous flashover of 220kV line is rare. Therefore, for 220kV double-circuit and 500kV double-circuit four-circuit lines on the same tower, the differential insulation method proposed by the present invention increases the insulation strength of the right cross-arm insulators on the upper three floors by 13%, and the insulation strength of the left cross-arm insulators on the upper three floors by 6.7% %, the insulation strength of the bottom two layers of cross-arm insulators increases by 7%, that is, the insulation strength of the first insulator increases by 6.7% on the original basis, the insulation strength of the second insulator increases by 13% on the original basis, and the third insulator increases by 13% on the original basis. Based on the increase of 7% of the dielectric strength.

(5) 500kV four-circuit line on the same tower:

The pole tower of the 500kV four-circuit line on the same tower has three layers of cross arms, and each layer of cross arms has 4 conductors. Relatively speaking, the double-circuit simultaneous flashover and multi-circuit simultaneous flashover of the 500kV four-circuit line on the same tower rarely occur. Therefore, the differential insulation method of the 500kV four-circuit line on the same tower is also relatively simple. It only needs to increase the insulation strength of one circuit by 3.6% as a weak insulation circuit, and increase the insulation level of the other three circuits by 7.1% as a strong insulation circuit, that is, the first insulator The dielectric strength is increased by 3.6% on the original basis, and the dielectric strength of the second insulator is increased by 7.1% on the original basis.

At present, domestic multi-circuit lines on the same tower are mostly used as double-circuit lines on the same tower. The present invention can also be applied to pole towers of double-circuit lines on the same tower. The following introduces the differentiated insulation configuration method of double-circuit lines on the same tower:

The general conductor arrangement of the double-circuit line on the same tower is that one of the two circuits occupies the left crossarm, and the other occupies the right crossarm, and the three-phase conductors of each circuit are arranged vertically, as shown in Figure 4.

(1) 110kV double circuit line

The double-circuit simultaneous tripping phenomenon of the 110kV double-circuit line on the same tower is very serious, and the single-circuit lightning resistance level is very close to the double-circuit simultaneous tripping lightning resistance level. For this line, the differential insulation configuration method we propose is to increase the insulation strength of one of the two circuits by 20%, and keep the insulation strength of the other circuit unchanged, that is, the first insulator remains the same as the original design, and the second insulator Insulator insulation strength increased by 20%. The double-circuit simultaneous tripping rate of the line under this configuration can be reduced to about 40% of the original, and the total tripping rate is also slightly reduced.

(2) 220kV double circuit line

For 220kV double-circuit lines on the same tower, the insulation strength of one circuit is increased by 15%, and the insulation strength of the other circuit remains unchanged. Under this configuration, the double-circuit simultaneous tripping rate of the line can be reduced to 40% of the original, that is The first insulator increases the insulation strength by 15% on the original basis, and the second insulator increases the insulation strength by 40% on the original basis.

(3) 500kV double circuit line

For 500kV double-circuit lines on the same tower, the insulation strength of one circuit is increased by 7.2%, and the insulation strength of the other circuit is increased by 3.6%, that is, the insulation strength of the first insulator is increased by 3.6% on the original basis. There is a 7.2% increase in dielectric strength on the basis. The double-circuit simultaneous tripping rate of the line under this configuration can be reduced to 50% of the original, and the total tripping rate can also be reduced.

In the actual implementation process, the method of achieving differentiated dielectric strength can be flexibly selected according to the actual situation of the insulator. The easiest way to achieve differentiated insulation is to increase the number of insulators or the length of the insulator. There are three types of insulators currently used: glass insulators, ceramic insulators, and synthetic silicone rubber insulators. Glass insulators and synthetic silicone rubber insulators are more commonly used in lines above 110kV. Among them, synthetic silicone rubber insulators must be used in high-pollution areas, and glass insulators and synthetic silicone rubber insulators can be used in low-pollution areas. Synthetic silicone rubber insulators need to be equipped with grading rings, so the insulation distance of synthetic silicone rubber insulators with the same structural length is relatively small. In low-pollution areas, different insulators can be mixed to achieve differentiated insulation effects.

In addition, installing an arc strike angle for the insulator can protect the insulator. The arc striking angle is connected in parallel with the insulator, and the breakdown occurs at the arc striking angle when lightning strikes, thereby protecting the insulator. The invention proposes a differential insulation lightning protection method using an arc striking angle, that is, each circuit insulator has improved insulation strength, and at the same time, an arc striking angle is installed on a set weak insulating circuit. The advantage of this differential insulation method is that while achieving the differential insulation effect, the arc strike angle can protect the insulators of the weak insulation circuit when lightning strikes.

Claims (1)

1. A four-circuit power transmission line on the same tower configured with differentiated insulators, characterized in that the power transmission line includes: tower ground wire, three first insulators, three second insulators, six third insulators, a support frame, A-phase wire of the first transmission line, B-phase wire of the first transmission line, C-phase wire of the first transmission line, A-phase wire of the second transmission line, B-phase wire of the second transmission line, The C-phase wire of the second transmission line, the A-phase wire of the third transmission line, the B-phase wire of the third transmission line, the C-phase wire of the third transmission line, the A-phase wire of the fourth transmission line, The B-phase conductor of the fourth circuit transmission line, the C-phase conductor of the fourth circuit transmission line; the A-phase conductor of the first circuit transmission line, the B-phase conductor of the first circuit transmission line and the C-phase conductor of the first circuit transmission line The phase conductors are erected on the upper part of one side of the support frame; the three first insulators are respectively erected on the A-phase conductor of the first circuit transmission line, the B-phase conductor of the first circuit transmission line, and the C-phase conductor of the first circuit transmission line, A weak insulation circuit is formed; the A-phase conductor of the second power transmission line, the B-phase conductor of the second power transmission line and the C-phase conductor of the second power transmission line are erected on the upper part of the other side of the support frame; The two insulators are erected respectively on the A-phase conductor of the second circuit transmission line, the B-phase conductor of the second circuit transmission line, and the C-phase conductor of the second circuit transmission line; The B-phase conductor of the three-circuit transmission line and the C-phase conductor of the third circuit transmission line are erected on the lower part of one side of the support frame; the A-phase conductor of the fourth circuit transmission line, the B-phase conductor of the fourth circuit transmission line and The C-phase conductor of the fourth circuit transmission line is erected on the lower part of the other side of the support frame; the six third insulators are respectively erected on the A-phase conductor of the third circuit transmission line, the B-phase conductor of the third circuit transmission line, A strong insulation circuit is formed on the C-phase conductor of the third circuit transmission line, the A-phase conductor of the fourth circuit transmission line, the B-phase conductor of the fourth circuit transmission line, and the C-phase conductor of the fourth circuit transmission line; The ground wire is erected on the top of the transmission tower; the tower grounding resistance is placed at the bottom of the transmission tower and connected to the earth.

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