CN104882876B - A kind of extra-high voltage direct current ground electrode circuit guard system - Google Patents

Abstract

The invention provides a UHV DC grounding electrode line protection system, which includes a tower body, a lightning protection wire crossarm and a grounding electrode wire crossarm arranged on the tower body. The two ends of the pole are respectively fixed by the insulator S1 and the insulator S2, the connection end of the ground electrode wire and the insulator S1 is connected to one end of the gap C1, the connection end of the ground electrode wire and the insulator S2 is connected to one end of the gap C2, and the gap C1 Both the other end and the other end of the gap C2 are connected to one end of the arrester, and the other end of the arrester is connected to the tower body. This technical solution can reduce the accidents of unipolar or even bipolar blocking caused by flashover of UHV DC grounding pole lines, and can realize that one arrester can protect two grounding pole lines, ensuring unbalanced current protection equipment, grounding Pole line disconnection detection and protection equipment operate correctly without being affected by the capacitance of the arrester to ground.

Description

A UHV DC Grounding Electrode Line Protection System

technical field

The invention relates to a protection system, in particular to a lightning and operation overvoltage protection system for an UHV DC grounding electrode line.

Background technique

The existing ±800kV and ±1000kV UHV DC grounding electrode lines generally adopt the method of insulators connected in series and parallel to prevent lightning and operating overvoltage from causing damage to the line; The fit coefficient is 0.7-0.85. Under lightning strike or operating overvoltage, the arcing angle flashes ahead of the insulator string, so that the DC continuous current flows through the arcing angle instead of the insulator string, so as to prevent the arc from burning out the insulator string, causing string drop, and It is beneficial to the DC current arc extinguishing on the arc striking angle.

However, the discharge characteristics of the striking arc angle and the extinguishing characteristics after flowing the operating DC current are greatly affected by environmental factors and are unstable. In the double-pole operation mode, when the single pole is grounded due to lightning strike, the healthy pole will turn into a single-pole ground operation mode. If the grounded pole line is subjected to direct lightning strikes and induction lightning, resulting in flashover of the arc angle, the DC operating current will flow through the arc. Because the DC operating current has no zero-crossing point, it is difficult to extinguish the arc at the arcing angle. It is necessary to perform a quick shutdown, block the converters at both ends, cut off the DC current flowing through the arcing angle, and then restart.

In densely populated areas with many AC substations, due to the limitation of corridors and the difficulty in selecting the location for the erection of grounding electrode lines, ±800kV and ±1000kV DC lines may be erected on the same pole as the grounding pole line, and the pole lines and grounding poles erected on the same pole The lines are strongly coupled lines. During bipolar operation, if any one of the pole lines is struck by lightning, the traveling lightning wave will propagate along the pole line to the erection section of the same pole. The voltage can cause flashover at multiple arcing angles on the grounding pole line; when lightning directly strikes the top of the line tower or overhead ground wire erected on the same pole, the lightning current flowing through the tower and entering the ground can also cause flashover at the arcing angle. Therefore, The lightning flashover probability of the ground electrode lines erected on the same pole is much higher than that of the ground electrode lines erected alone.

During bipolar operation, if lightning shielding or counterattack causes a ground fault on one pole line, the operating overvoltage will be induced on the pole line of the healthy pole, and the traveling wave of the operating overvoltage will be transmitted to the erection section of the same pole, and will be transmitted Capacitive coupling induces a high operating overvoltage on the ground pole line, especially after the ground fault occurs on the high-end converter valve side of the inverter station and the pole line of the section erected on the same pole, the operating overvoltage generated on the ground pole line is the highest , this operating overvoltage can lead to arc flashover. The operation experience shows that the ±800kV grounding electrode line has repeatedly caused unipolar or even bipolar blockage due to the flashover of the arc angle, or there have been major accidents where the arc angle cannot be extinguished and continued to burn until the arc angle is burned, and the insulators have been dropped.

Contents of the invention

In order to solve the above-mentioned deficiencies in the prior art, the present invention provides a UHV DC grounding electrode line protection system.

The technical solution provided by the present invention is: a UHV DC grounding electrode line protection system, including a tower body, a lightning protection wire crossarm and a grounding electrode wire crossarm arranged on the tower body, the two ends of the lightning protection wire crossarm The lightning conductors are respectively fixed, and the two ends of the cross arm of the ground electrode wire are respectively fixed by the insulator S1 and the insulator S2. connection, the connecting end of the ground electrode wire and the insulator S2 is connected to one end of the gap C2, the other end of the gap C1 and the other end of the gap C2 are connected to one end of the arrester, and the other end of the arrester is connected to the tower Ontology connected.

Preferably, the tower body, the lightning conductor cross-arm and the ground electrode conductor cross-arm are all angle steel trusses, the lightning conductor cross-arm is higher than and parallel to the ground pole conductor cross-arm, and the lightning conductor The vertical mid-perpendicular line of the cross arm and the ground electrode wire cross arm coincides with the axis of the tower body.

Preferably, the tower body is provided with installation holes for fixing the lightning conductor cross-arm and the ground electrode conductor cross-arm, and the lightning conductor cross-arm and the ground electrode conductor cross-arm are provided with apertures and The apertures of the installation holes on the tower body correspond to the same screw holes; the lightning conductor crossarm and the grounding electrode wire crossarm are fixed on the tower body by bolts passing through the installation holes and the screw holes.

Preferably, the two ends of the cross-arm of the lightning conductor are respectively provided with fixing holes for fixing the clamp of the lightning conductor; the clamp of the lightning conductor is provided with a screw hole whose aperture is equal to that of the fixing hole, and the lightning conductor The clamps are fixed on both ends of the cross-arm of the lightning conductor through the bolts passing through the fixing hole and the screw hole; the lightning conductor is fixed on both ends of the cross-arm of the lightning conductor horizontally and vertically .

Preferably, the insulator is a suspension insulator, one end of the suspension insulator is provided with an insulator fitting, and the other end is provided with a clamp; holes, the insulator metal is fixed on both ends of the grounding electrode wire cross-arm through bolts and nuts; the clamp clamps the grounding electrode wire.

Preferably, the arrester is a suspension arrester; both the high-voltage end and the low-voltage end of the arrester are equipped with arrester fittings;

The lightning arrester hardware at the low-voltage end includes a rectangular metal plate, connecting plates and metal wire clips that are vertically arranged at both ends of the rectangular metal plate;

The connecting plate and the angle steel truss of the tower body are provided with screw holes corresponding to the same size, and the connecting plate is fixed to the tower body through bolts and nuts passing through the screw holes, and the screw on the tower body The position of the hole is lower than or equal to the height of the cross arm of the ground electrode wire; the metal clamp is fixed to the low-voltage end of the arrester.

Preferably, one end of the gap is connected to the ground electrode wire through an insulator clamp, and the other end is connected to the metal fitting at the high voltage end of the arrester through a hard wire.

Preferably, the distance between the gaps is the length corresponding to when the voltage drop of the gap under the overload direct current does not produce corona when the UHV DC grounding electrode line operates in a single pole ground mode and an overload mode.

Further, the distance between the lightning arrester and the tower body is greater than the distance between the gaps.

Compared with the closest technical solution, the present invention has the following remarkable progress:

(1) In this technical solution, the gap is connected in series with the suspension arrester and then connected in parallel with the insulator. Due to the effect of the suspension arrester, even if the ground electrode line is erected alone or on the same pole as the pole line, the flashover grounding of the ground electrode line will cause the gap to break down, and the electricity flowing through the gap The DC operating current will also be reduced quickly, which solves the problem that the arcing angle is difficult to extinguish when the DC operating current flows, and reduces the accidents of unipolar or even bipolar blocking caused by the flashover of the arcing angle of the UHV DC grounding electrode line.

(2) The suspension arrester selected in this technical solution makes it more convenient to install the arrester on the tower, and the gap is connected to the high-voltage end of the suspension arrester. During normal operation, the suspension arrester will not be affected by the DC working voltage, which extends the length of the arrester. service life.

(3) In this technical solution, the ground electrode wires on both sides are respectively connected to one end of the gap C1 and one end of the gap C2, the other end of the gap C1 and the other end of the gap C2 are connected to one end of the arrester, and the other end of the arrester is connected to the tower body , It can realize that one arrester can protect two grounding electrode lines, ensure the correct operation of unbalanced current protection equipment and grounding electrode line disconnection detection and protection equipment, and is not affected by the capacitance of the arrester to the ground.

(4) The low-voltage end of the arrester is fixed to the tower body through the arrester fittings at the low-voltage end, which can ensure that the distance between the suspended arrester and the tower body is greater than the voltage of the gap under the overload DC current when the UHV DC grounding electrode line operates in a single-pole mode. Reduce the corresponding spacing when no corona is generated, so as to ensure that the high-voltage end of the arrester will not discharge the tower body after the gap breaks down in the event of a fault.

(5) The gap is connected to the lightning arrester through hard wires, which can ensure that the connecting wires do not swing with the wind, and ensure the relative distance between the hard wires and other components during normal operation.

Description of drawings

Fig. 1 is a structural principle diagram of the UHV DC grounding electrode line protection system provided by the present invention.

Figure 2 is a schematic diagram of the connection between the low-voltage end of the arrester and the tower body.

Figure 3 is a schematic diagram of the connection between the insulator and the ground electrode wire and the gap.

Among them: 1- tower body; 2- lightning protection wire cross arm; 3- lightning protection wire; 4- grounding electrode wire cross arm; 5- insulator; 6- grounding electrode wire; -nut; 10-bolt; 11-lightning arrester hardware at the low-voltage end; 12-insulator clamp; 13-gap.

Detailed ways

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

The UHV DC grounding electrode line protection system provided by the present invention is shown in Figure 1, which is mainly used to prevent lightning and operating overvoltage from causing damage to the UHV DC grounding electrode line; the protection system includes a vertically erected tower body 1, a The lightning conductor cross-arm 2 and the grounding electrode conductor crossarm 4 on the tower body 1 and the vertical mid-perpendicular line coincides with the axis of the tower body 1; wherein the lightning conductor crossarm 2 is higher than and parallel to the ground pole conductor crossarm 4;

The two ends of the ground electrode wire cross arm 4 are respectively fixed by the insulator S1 and the insulator S2 to fix the ground electrode wire 6, the connection end of the ground electrode wire 6 is connected to the connection end of the insulator S1 and one end of the gap C1, and the ground electrode wire 6 The connecting end of the insulator S2 is connected to one end of the gap C2, the other end of the gap C1 and the other end of the gap C2 are connected to one end of the arrester 7, and the other end of the arrester 7 is connected to the tower body 1; the gap C1 and C2 are air gaps. When an overvoltage occurs, the air between the gaps will be broken down. After the breakdown, the gap is connected in series with the arrester 7 to prevent the insulators S1 and S2 from being damaged by the overvoltage; this connection method can be used One lightning arrester 7 protects two grounding electrode lines to ensure the correct operation of the unbalanced current protection equipment and the grounding electrode line disconnection detection protection equipment, and is not affected by the ground capacitance of the lightning arrester 7 .

The tower body 1, the lightning conductor cross arm 2 and the grounding electrode conductor cross arm 4 are all angle steel trusses, and the angle steel truss 8 of the tower body is provided with a truss for fixing the lightning conductor cross arm 2 and the The installation hole of the ground electrode wire cross arm 4, the lightning protection wire cross arm 2 and the ground electrode wire cross arm 4 are all provided with screw holes with apertures corresponding to the apertures of the installation holes on the tower body 1; The lightning conductor crossarm 2 and the ground electrode conductor crossarm 4 are fixed on the tower body 1 through bolts passing through the installation holes and the screw holes.

The two ends of the lightning conductor cross-arm 2 are respectively provided with fixing holes for fixing the lightning conductor clamps; the lightning conductor clamps are provided with screw holes whose apertures are equal to the apertures of the fixing holes, and the lightning conductor clamps The bolts passing through the fixing holes and the screw holes are fixed at both ends of the lightning conductor cross-arm 2; the lightning conductor clamp tightens the lightning conductor 3, and the lightning conductor 3 is fixed horizontally and vertically on the lightning conductor Cross arm 2 two ends.

The arrester 7 is a suspended arrester, which makes it more convenient to install the arrester 7 on the tower; the high-voltage end and the low-voltage end of the arrester 7 are provided with arrester fittings; the high-voltage end of the arrester 7 is connected to the gap 13 through the arrester fittings. , the suspension arrester will not be affected by the DC working voltage, prolonging the service life of the arrester 7 .

As shown in Figure 2: the lightning arrester hardware 11 at the low-voltage end includes a rectangular metal plate, connecting plates and metal wire clips that are vertically arranged at both ends of the rectangular metal plate;

The connecting plate and the angle steel truss 8 of the tower body are provided with screw holes corresponding to the same size, and the connecting plate is fixed to the tower body 1 through bolts 10 and nuts 9 passing through the screw holes. The position of the screw hole on the body 1 is lower than or equal to the height of the ground electrode wire cross arm 4; the metal clamp is fixed to the low-voltage end of the arrester 7 .

The low-voltage end of the arrester 7 is fixed to the tower body 1 through the arrester fitting 11 at the low-voltage end, which can ensure that the distance between the suspended arrester 7 and the tower body 1 is greater than that of the UHV DC grounding electrode line. The distance corresponding to the voltage drop that flows down does not produce corona, thereby ensuring that the high-voltage end of the arrester 7 will not discharge the tower body 1 after the gap 13 breaks down under fault conditions.

The distance between the gaps 13 is the length corresponding to when the voltage drop of the gaps 13 under the overload DC current does not produce corona when the UHV DC grounding electrode line operates in a single pole ground mode and an overload mode.

As shown in Figure 3: the insulator 5 is a suspension insulator, one end of the suspension insulator is provided with an insulator fitting, and the other end is provided with a wire clip; There are screw holes corresponding to the size, and the insulator metal is fixed at both ends of the ground electrode wire cross arm 4 through bolts and nuts;

The clamp clamps the ground electrode wire 6 and connects one end of the gap 13, and the other end of the gap 13 is connected to the metal fitting at the high voltage end of the arrester 7 through a hard wire, so that the connecting wire does not swing with the wind and ensures normal operation. The relative distance of hard wires to other components at runtime.

The rated voltage of the arrester 7 is determined by the following steps:

Step 1: Establish a simulation calculation model to calculate the ground flashover, commutation failure, or ground fault along the line at the highest and lowest converter valve sides of the converter transformer. Operation overvoltage, lightning shielding or counter-grounding occurs on the ground electrode line When an overvoltage fault occurs in the pole line, the lightning and operating overvoltage protection level of the arrester;

Step 2: Perform insulation coordination to select the air gap of the insulator string and the protection level of the arrester;

Step 3: Select the corresponding rated voltage of the arrester according to the protection level of the arrester and the rated voltage of the neutral bus.

The above is only an embodiment of the present invention, and is not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention are all pending applications for the rights of the present invention. within the scope of requirements.

Claims (9)

1. A UHV DC grounding pole line protection system, comprising a tower body, a lightning conductor crossarm and a grounding pole wire crossarm arranged on the pole tower body, and lightning conductors are respectively fixed at both ends of the lightning conductor crossarm, so that The two ends of the cross-arm of the ground electrode wire are respectively fixed by the insulator S1 and the insulator S2. The connecting end of the insulator S2 is connected to one end of the gap C2, the other end of the gap C1 and the other end of the gap C2 are both connected to one end of the arrester, and the other end of the arrester is connected to the tower body. 2. A UHV DC grounding electrode line protection system as claimed in claim 1, characterized in that: The tower body, the lightning conductor crossarm and the grounding pole conductor crossarm are all angle steel trusses, the lightning conductor crossarm is higher than and parallel to the ground pole conductor crossarm, and the lightning conductor crossarm and The vertical mid-perpendicular line of the ground electrode conductor cross-arm coincides with the axis of the tower body. 3. A UHV DC grounding electrode line protection system as claimed in claim 1, characterized in that: The tower body is provided with mounting holes for fixing the lightning conductor crossarm and the grounding electrode conductor crossarm, and both the lightning conductor crossarm and the grounding conductor conductor crossarm are provided with apertures corresponding to the pole tower. The apertures of the mounting holes on the body correspond to equal screw holes; the lightning conductor crossarm and the grounding electrode conductor crossarm are fixed on the tower body by bolts passing through the mounting holes and the screw holes. 4. A UHV DC grounding electrode line protection system as claimed in claim 1, characterized in that: The two ends of the cross-arm of the lightning conductor are respectively provided with fixing holes for fixing the clamp of the lightning conductor; the clamp of the lightning conductor is provided with a screw hole whose aperture is equal to that of the fixing hole, and the clamp of the lightning conductor passes through Bolts passing through the fixing holes and the screw holes are fixed to both ends of the lightning conductor cross-arm; the lightning conductor is vertically fixed horizontally and vertically to both ends of the lightning conductor cross-arm through the lightning conductor clamp. 5. A UHV DC grounding electrode line protection system as claimed in claim 1, characterized in that: The insulator is a suspension insulator, one end of the suspension insulator is provided with an insulator fitting, and the other end is provided with a wire clamp; the two ends of the insulator fitting and the cross-arm of the ground electrode wire are respectively provided with corresponding screw holes, so The insulator fittings are fixed on both ends of the ground electrode wire cross-arm through bolts and nuts; the wire clamp clamps the ground electrode wire. 6. A UHV DC grounding electrode line protection system as claimed in claim 1, characterized in that: The arrester is a suspension arrester; both the high voltage end and the low voltage end of the arrester are equipped with arrester fittings; The lightning arrester hardware at the low-voltage end includes a rectangular metal plate, connecting plates and metal wire clips that are vertically arranged at both ends of the rectangular metal plate; The connecting plate and the angle steel truss of the tower body are provided with screw holes corresponding to the same size, and the connecting plate is fixed to the tower body through bolts and nuts passing through the screw holes, and the screw on the tower body The position of the hole is lower than or equal to the height of the cross arm of the ground electrode wire; the metal clamp is fixed to the low-voltage end of the arrester. 7. A UHV DC grounding electrode line protection system as claimed in claim 1, characterized in that: One end of the gap is connected to the ground electrode wire through an insulator clamp, and the other end is connected to the metal fitting at the high voltage end of the arrester through a hard wire. 8. A UHV DC grounding electrode line protection system as claimed in claim 1, characterized in that: The distance between the gaps is the corresponding length when the voltage drop of the gap under the overload DC current does not produce corona when the UHV DC grounding electrode line operates in a single pole ground mode and an overload mode. 9. A UHV DC grounding electrode line protection system as claimed in claim 8, characterized in that: The distance between the lightning arrester and the tower body is greater than the distance between the gaps.