CN115856555A - Delineation and prevention method of foreign object flashover risk area of a disconnector - Google Patents

Abstract

The invention discloses a method for defining and preventing a foreign matter flashover risk area of an isolating switch, which comprises the steps of carrying out a foreign matter flashover simulation test of the isolating switch at a certain moment when a foreign matter falls through iron wire simulation, changing the length of the iron wire and the horizontal distance between the iron wire and a post insulator to obtain flashover voltage, successively determining the foreign matter flashover critical distance of a low-voltage end and a high-voltage end of the isolating switch by taking the highest running phase voltage of the isolating switch as a reference, drawing the foreign matter flashover risk area of the isolating switch, and finally shielding the foreign matter flashover risk area by adopting an isolating switch bird prevention device. The invention can provide reference for preventing bird-related faults of the disconnecting switch of the transformer substation and improve the safe and stable operation capability of the power grid.

Description

Delineation and prevention method of foreign object flashover risk area of a disconnector

technical field

The invention relates to the technical field of substation bird prevention, in particular to a method for demarcating and preventing flashover risk areas of foreign objects in isolating switches.

Background technique

With the continuous increase of social demand for electricity, substations are also constantly being constructed and expanded, and the increase in birds brought about by the improvement of the ecological environment in recent years also threatens the security of the power grid. From the perspective of actual power equipment failure types, the number of power grid failure events caused by bird activities has increased year by year, and at the same time, the actual economic losses and social impacts have continued to increase. Especially in substations in areas with superior natural environment, the growth of bird species and numbers threatens the power supply security of substations. During the construction of the substation, due to the needs of urban development, the construction mode is far away from the urban area, and there are few people in the vicinity. Compared with the surrounding environment, the substation has sufficient light at night, and a large number of insects will gather near the substation attracted by the light. These insects are birds. With sufficient supply, the flock of birds will continue to fly between the substation equipment while eating, and it is easy to touch the substation equipment and wires, which also makes it more susceptible to the impact of bird activities.

There are gaps between the contacts of the isolating switch and the metal fittings above the insulator, which are easy to attract birds to build nests. When wet bird droppings or bird’s nest materials fall, it may cause the insulator of the isolating switch to discharge, affecting the safe and stable operation of the isolating switch. For a long time, scholars at home and abroad have carried out a series of observations and statistical work on the problem of bird-related faults in power grids, and proposed and applied some different types of bird-related fault prevention and control measures. targeted preventive measures.

Contents of the invention

The purpose of the invention is to provide a reference for substation prevention and control of bird-related faults in isolating switches, and improve the ability of safe and stable operation of the power grid.

The object of the present invention is achieved in this way: a method for delimiting and preventing the flashover risk area of a disconnector,

The post insulator of the isolating switch is erected on the insulating support platform. Contacts are arranged above the fittings on the post insulator. The contacts are electrically connected to the high-voltage end, and the fittings under the post insulator are grounded;

Under the condition that the upper end of the simulated foreign object is flush with the lower surface of the upper metal fitting of the post insulator, and the length of the simulated foreign object and the horizontal distance from the post insulator are changed, the foreign object flashover simulation test is carried out, and the flashover voltage is recorded. When the flashover voltage is equal to When the difference between the highest operating phase voltage of the isolating switch is not greater than the set percentage, the distance between the lower end of the simulated foreign object and the upper surface of the lower metal fitting of the post insulator is the critical distance for flashover of the foreign object at the low-voltage end of the isolating switch; make the lower end of the simulated foreign object and the post insulator The distance between the upper surfaces of the lower fittings is that the critical distance of foreign matter flashover at the low-voltage end remains unchanged, the length of the simulated foreign matter and the horizontal distance from the post insulator are changed, and the foreign matter flashover simulation test is carried out to determine the flashover voltage. If the difference of the highest operating phase voltage is not greater than the set percentage, the distance between the upper end of the simulated foreign object and the lower surface of the upper metal fitting of the post insulator is the critical distance for foreign object flashover at the high voltage end of the disconnector;

Taking the critical distance of foreign matter flashover at the high-voltage end of the disconnector and the critical distance of foreign matter flashover at the low-voltage end of the disconnector as the radius, draw the risk areas of foreign matter flashover at the high-voltage end and low-voltage end of the post insulator. In the foreign object flashover risk area at the low-voltage end, breakdown will occur in the gap near the post insulator to cause flashover, and the shortest distance between the foreign object flashover risk areas is the critical foreign object length;

The size of the bird-proof device of the disconnector is determined according to the size of the foreign object flashover risk area and the size of the post insulator.

Further preferably, the simulated foreign matter is iron wire.

Further preferably, the insulating rope is fixed above the contact through a hook, and the iron wire is fixed on the insulating rope with an insulating tape to hang vertically.

Further preferably, the foreign body flashover simulation test: the test is carried out by using the uniform boost method, and the voltage is boosted rapidly for the first time until a flashover occurs, and the flashover voltage is recorded, and the flashover process is recorded with a camera. If the difference of the highest operating phase voltage is greater than the set percentage, then keep the upper end of the simulated foreign object flush with the lower surface of the upper fitting of the post insulator or make the distance between the lower end of the simulated foreign object and the upper surface of the lower fitting of the post insulator the critical flashover of the foreign object at the low-voltage end The distance remains unchanged, and the length of the simulated foreign object and the horizontal distance from the post insulator are changed to retest. If the difference between the flashover voltage and the highest operating phase voltage of the disconnector is not greater than the set percentage, repeated tests are carried out, and the flashover voltage is taken as average of.

Further preferably, for a disconnector composed of multiple post insulators, the foreign matter flashover risk area also includes the area where single-section or multi-section post insulators flashover, and the foreign matter of single-section and multi-section post insulators needs to be checked from top to bottom. Flashover simulation test.

Further preferably, the anti-bird device of the isolating switch realizes the prevention and control of foreign matter flashover faults by blocking the gap between the foreign matter and the post insulator hardware.

Further preferably, the bird-proof device of the isolating switch includes two hollow semicircular epoxy resin plates, the inner radius of the hollow semicircular epoxy resin plate is the radius of the umbrella pole of the pillar insulator, and the outer radius is the risk area of foreign matter flashover at the high voltage end of the pillar insulator plus the pillar The radius of the upper fitting of the insulator is fixed above the lower fitting of the post insulator through bolt holes connecting two hollow semicircular epoxy resin plates.

Beneficial effects of the present invention: the present invention uses static iron wires to simulate a certain moment when foreign matter such as bird droppings and bird's nest materials fall, and carries out a foreign matter flashover simulation test of a disconnector, and changes the length of the iron wire and the horizontal distance from the post insulator to obtain the flashover voltage , based on the highest operating phase voltage of the isolating switch, the critical distance of foreign object flashover at the low-voltage end and high-voltage end of the isolating switch is successively determined, and the foreign object flashover risk area of the isolating switch is drawn, and finally the prevention and control measures are used to block the foreign object flashover risk area. It can provide reference for the prevention and control of bird-related faults of isolating switches in substations, and improve the ability of safe and stable operation of the power grid.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application or the conventional technology, the following will briefly introduce the accompanying drawings that need to be used in the description of the embodiments or the traditional technology. Obviously, the accompanying drawings in the following description are only the present invention For some embodiments of the application, those skilled in the art can also obtain other drawings based on these drawings without creative work.

Fig. 1 is the overall flow chart of the present invention.

Fig. 2 is a layout diagram of the foreign object flashover simulation test of the isolating switch of the present invention.

Fig. 3 is a structural schematic diagram of the control measures of the present invention.

Figure 4 is a schematic diagram of the installation of the preventive measures of the present invention.

Fig. 5 is a diagram of the foreign matter flashover risk area of the embodiment of the present invention.

Explanation of reference signs: 21. Post insulator, 22. Contact, 23. Insulated wire, 24. Insulated rope, 25. Hook, 26. Insulated tape, 27. Iron wire, 28. DV camera, 29. Insulated support platform, 31 .Hollow semi-circular epoxy resin plate, 32. Bolt holes, 41. Bird-proof device for isolating switch, 42. Upper fittings for post insulators, 43. Umbrella pole for post insulators, 44. Lower fittings for post insulators.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

When the air breaks down, the development speed of the electron avalanche is about 1.25×10 ⁷ cm/s, the development speed of the stream column is about 7×10 ⁷ ～8×10 ⁷ cm/s, and the development speed of the leader is about 10 ⁶ ～10 ⁷ cm/s. Taking a 220 kV isolating switch as an example, the breakdown gap distance is about 36 cm, and the breakdown time is about 10 ^-6 s according to calculation. Assuming that the total length of the foreign object in free fall is 200 cm, in the last 1 cm distance, the average falling speed of the foreign object is the fastest, and the time required to pass 1 cm at this time is 1.84 ms, the order of magnitude is more than 100 times that of the breakdown process. Therefore, during the breakdown process, the foreign matter can be considered to be stationary. In a humid and dirty environment, bird droppings and bird nest materials have high conductivity and can be regarded as conductors. Therefore, static iron wires can be used to simulate bird droppings and bird nest materials. A certain moment when a foreign object such as bird's nest material falls. Therefore, the present invention proposes a demarcation and prevention method for the foreign matter flashover risk area of the isolating switch. By using a static iron wire to simulate a certain moment when foreign matter such as bird droppings and bird’s nest materials falls, the foreign matter flashover simulation test of the isolating switch is carried out to determine the foreign matter flashover. risk area.

Overall process and test arrangement of the present invention are shown in Figure 1-Figure 2, specifically include:

Step S1: Clean and dry the post insulator 21 of the isolating switch, and set it up on the insulating support platform 29. The contact 22 is arranged above the metal fitting 42 on the post insulator, and the contact 22 passes through the insulated wire 23 (the wire with the outer insulation layer) Connected to the high voltage end, the lower fitting 44 of the post insulator is grounded through another insulated wire 23 , and the insulating rope 24 is fixed above the contact 22 through the hook 25 .

Step S2: fix a certain length of iron wire 27 with a diameter of 3 mm on the insulating rope 24 with insulating tape 26 and hang vertically, and keep a certain horizontal distance between the iron wire 27 and the post insulator 21. The lower surfaces of the fittings 42 are flush.

Step S3: After the iron wire 27 is fixed, the foreign body flashover simulation test is carried out by using the uniform boost method. If the difference with the highest operating phase voltage of the isolating switch is greater than 10%, keep the upper end of the iron wire 27 flush with the lower surface of the upper fitting 42 of the post insulator, change the length of the iron wire 27 and the horizontal distance from the post insulator 21 and re-test, if the flashover voltage If the difference with the highest operating phase voltage of the isolating switch is ≤ 10%, then carry out 4 repeated tests, and each time the voltage is first raised to the vicinity of the expected flashover voltage, and then each time the voltage is increased to 10% to 20% of the expected flashover voltage. Speed up the voltage until flashover occurs. The interval between two tests is 1 to 2 minutes, and then take the average value with an error of no more than 10% as the flashover voltage in this case. If the flashover voltage is the same as the highest operating phase voltage of the isolating switch If the difference is less than or equal to 1%, the distance between the lower end of the iron wire 27 and the upper surface of the lower fitting of the post insulator is the critical distance for the flashover of foreign matter at the low-voltage end of the disconnector. Otherwise, change the length of the iron wire 27 and the horizontal distance from the post insulator 21 to retest.

Step S4: The difference from step S3 is that the upper end of the iron wire 27 is no longer kept flush with the lower surface of the upper fitting 42 of the post insulator, but the distance between the lower end of the iron wire 27 and the upper surface of the lower fitting 44 of the post insulator is equal to the flashover of foreign matter at the low-voltage end Critical distance, change the length of the iron wire 27 and the horizontal distance from the post insulator 21, repeat the foreign body flashover simulation test in step S3 to determine the flashover voltage, if the difference between the flashover voltage and the highest operating phase voltage of the disconnector is ≤1%, Then the distance between the upper end of the iron wire 27 and the lower surface of the upper fitting 42 of the post insulator is the critical distance for the flashover of foreign matter at the high voltage end of the disconnector.

Step S5: Taking the foreign object flashover critical distance at the high voltage end of the disconnector and the foreign object flashover critical distance at the low voltage end of the isolating switch as the radius, draw the foreign object flashover risk areas at the high voltage end and low voltage end of the post insulator. In the foreign object flashover risk area of the high-voltage end and the low-voltage end, the gap near the post insulator 21 must be broken down to cause flashover, and the shortest distance between the foreign object flashover risk areas is the critical foreign object length.

Step S6: Determine the size of the bird-proof device 41 for the isolating switch according to the size of the foreign body flashover risk area and the size of the post insulator 21 .

The foreign object flashover risk area is for the isolating switch composed of multiple post insulators 21 of 220 kV and above, and also includes the flashover area of single-section or multi-section post insulators. Simulation test of foreign body flashover of post insulators.

The anti-bird device 41 of the isolating switch, as shown in Figure 3-Figure 4, realizes the prevention and control of foreign matter flashover faults by blocking the gap between the foreign matter and the post insulator fittings, including two hollow semicircular epoxy resin plates 31, hollow The inner radius of the semicircular epoxy resin plate 31 is the radius of the umbrella pole 43 of the pillar insulator, and the outer radius is the risk area of foreign matter flashover at the high voltage end of the pillar insulator plus the radius of 42 of the metal fittings on the pillar insulator. Two hollow semicircular epoxy resin plates 31 are connected by bolts. The bolt hole 32 is fixed above the lower fitting 44 of the post insulator.

The anti-bird device 41 of the isolating switch is made of epoxy resin insulating material to ensure that the insulation distance between the phases of the isolating switch will not be reduced after installation. The anti-bird device 41 of the isolating switch is installed on the lower fitting 44 of the post insulator, and the shielding range is foreign objects at the high-voltage end In this way, it can be ensured that when the upper end of the foreign object is located in the risk area of foreign object flashover at the high voltage end, even if the lower end of the foreign object is located in the area of risk of foreign object flashover at the low voltage end, the air gap between the foreign object and the lower fitting 44 of the post insulator is protected by the isolating switch. The bird device 41 is blocked, and the flashover channel cannot be formed, and the prevention and control of the foreign object flashover fault is realized. In addition, the anti-bird device 41 of the isolating switch is installed under the post insulator 21 to prevent the post insulator from being washed by rainwater and accumulating a large amount of pollution. hidden dangers to ensure the safety of equipment operation.

A specific embodiment provided by the present invention is shown in Fig. 5, which is a diagram of the foreign object flashover risk area of the post insulator of a certain type of disconnector, in which area 1 and area 2 are the risk of foreign object flashover that causes the entire post insulator of the disconnector to flashover Areas, area 3 and area 4 are the foreign body flashover risk areas that cause the flashover of the upper post insulator of the disconnector; according to the test, the distance between area 1 and the upper fitting 42 of the post insulator is 266 mm, and the distance between area 2 and the lower fitting 44 of the post insulator The distance between area 3 and the upper fitting 42 of the post insulator is 204 mm, and the distance between area 4 and the middle fitting of the post insulator is 279 mm.

Then determine the size of the corresponding bird-proof device 41 of the isolating switch. The radius of the post insulator umbrella pole 43 is 65 mm, and the radius of the metal fitting 42 on the post insulator is 90 mm. Therefore, the inner diameter of the bird-proof device 41 of the isolating switch is r=65 mm. If only the upper half The post insulator 21 flashover, the outer diameter R=204+90=294 mm of the anti-bird device 41 of the isolation switch; if the flashover of the entire post insulator 21 is prevented, the outer diameter R=266+90=356 mm of the anti-bird device 41 of the isolation switch, finally Fix the bird-proof device 41 of the isolating switch above the lower fitting 44 of the post insulator.

Finally, it should be noted that: the above is only a preferred example of the present invention, and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, it can still The technical solutions recorded in the foregoing embodiments are modified, or some of the technical features are equivalently replaced. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (7)

1. A method for defining and preventing a foreign body flashover risk area of an isolating switch is characterized by comprising the following steps:

a pillar insulator of the isolating switch is erected on the insulating support table, a contact is arranged above a hardware fitting on the pillar insulator, the contact is electrically connected with a high-voltage end, and a hardware fitting below the pillar insulator is grounded;

under the condition that the upper end of the simulated foreign matter is flush with the lower surface of the upper hardware fitting of the post insulator, a foreign matter flashover simulation test is carried out under the condition that the length of the simulated foreign matter and the horizontal distance between the simulated foreign matter and the post insulator are changed, flashover voltage is recorded, and when the difference value between the flashover voltage and the highest running phase voltage of the isolating switch is not more than a set percentage, the distance between the lower end of the simulated foreign matter and the upper surface of the lower hardware fitting of the post insulator is the critical distance of foreign matter flashover at the low-voltage end of the isolating switch; enabling the distance between the lower end of the simulated foreign body and the upper surface of the lower hardware fitting of the post insulator to be equal to the critical flashover distance of the foreign body at the low-voltage end, changing the length of the simulated foreign body and the horizontal distance between the simulated foreign body and the post insulator, carrying out a foreign body flashover simulation test to determine a flashover voltage, and if the difference value between the flashover voltage and the highest operation phase voltage of the isolating switch is not more than a set percentage, enabling the distance between the upper end of the simulated foreign body and the lower surface of the upper hardware fitting of the post insulator to be equal to the critical flashover distance of the foreign body at the high-voltage end of the isolating switch;

respectively drawing foreign matter flashover risk areas of a high-voltage end and a low-voltage end of a post insulator by taking a foreign matter flashover critical distance of the high-voltage end of the isolating switch and a foreign matter flashover critical distance of the low-voltage end of the isolating switch as radiuses, wherein when the foreign matter flashover risk areas of the high-voltage end and the low-voltage end of the isolating switch are respectively simulated at two ends of a foreign matter, a gap near the post insulator is bound to be punctured to cause flashover, and the shortest distance between the foreign matter flashover risk areas is the critical foreign matter length;

and determining the size of the anti-bird device of the disconnecting switch according to the size of the foreign matter flashover risk area and the size of the post insulator.

2. The method for defining and preventing the foreign body flashover risk area of the isolating switch according to claim 1, which is characterized in that: the simulated foreign bodies are iron wires.

3. The method for defining and preventing the foreign matter flashover risk area of the isolating switch according to claim 2, which is characterized in that: the insulating rope is fixed above the contact through the hook, and the iron wire is fixed on the insulating rope by the insulating adhesive tape and vertically droops.

4. The method for defining and preventing the foreign body flashover risk area of the isolating switch according to claim 1, which is characterized in that: the foreign matter flashover simulation test comprises the following steps: the method comprises the steps of adopting an even boosting method to test, rapidly boosting for the first time until flashover occurs, recording flashover voltage, recording a flashover process by using a camera, if the difference value of the flashover voltage and the highest operation phase voltage of an isolating switch is larger than a set percentage, keeping the upper end of a simulated foreign body flush with the lower surface of an upper hardware fitting of a post insulator or enabling the distance between the lower end of the simulated foreign body and the upper surface of the lower hardware fitting of the post insulator to be equal to the flashover critical distance of the foreign body at a low-voltage end, changing the length of the simulated foreign body and the horizontal distance with the post insulator to test again, if the difference value of the flashover voltage and the highest operation phase voltage of the isolating switch is not larger than the set percentage, carrying out repeated tests for many times again, and taking the average value of the flashover voltage.

5. The method for defining and preventing the foreign body flashover risk area of the isolating switch according to claim 1, which is characterized in that: for an isolating switch consisting of a plurality of post insulators, the foreign matter flashover risk area also comprises an area for single-section or multi-section post insulators to flashover, and foreign matter flashover simulation tests of the single-section and multi-section post insulators are needed to be respectively carried out from top to bottom.

6. The method for defining and preventing the foreign body flashover risk area of the disconnecting switch according to claim 1, which is characterized in that: the anti-bird device of the isolating switch realizes the prevention and the treatment of the flashover fault of the foreign matter by blocking the gap between the foreign matter and the post insulator hardware fitting.

7. The method for defining and preventing the foreign matter flashover risk area of the isolating switch according to claim 6, which is characterized in that: the anti-bird device of the isolating switch comprises two hollow semicircular epoxy resin plates, the inner radius of each hollow semicircular epoxy resin plate is the radius of an umbrella rod of the post insulator, the outer radius of each hollow semicircular epoxy resin plate is the radius of a hardware fitting on the post insulator in addition to a foreign matter flashover risk area at the high-voltage end of the post insulator, and bolt holes for connecting the two hollow semicircular epoxy resin plates through bolts are fixed above the hardware fitting under the post insulator.

Images