Fault and prevention of the hottest transmission l

2022-10-15
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Transmission line fault and prevention

transmission line is like the "artery" in the power system. Once a fault occurs, it may affect the power supply safety of one or several areas, and even cause immeasurable losses. Therefore, preventing transmission line faults has always been an important work for power supply enterprises. Transmission line fault is the abnormal operation of the line caused by the damage of the original electrical or mechanical properties of the components of the line, such as conductors, lightning wires, insulators, fittings, towers, foundations, grounding devices, or the distance between the live body and the grounding body is less than the specified value. Take Karamay area 3 In order to ensure the safety and correctness of the experiment, there have been transmission line faults caused by lightning around the main transformer, insulator deterioration, pollution flashover, tower stay wire theft, bird damage, conductor sag reduction and distribution line fault overstepping. In order to ensure the safe operation of transmission lines, effective preventive measures must be taken

1 causes of lightning damage and preventive measures

1.1 causes of lightning damage

lightning damage is not common in Karamay area, because the climate in this area is dry and there are relatively few thunderstorms throughout the year. Nevertheless, the lightning disaster still brought heavy losses to Karamay Power Supply Company. For example, in 1997, the main transformer of the South simple substation in the Fifth District suffered from lightning, resulting in a power outage of up to 11h in this area. The reason for this fault is that the grounding device is rusted and the grounding condition is poor

1.2 preventive measures

for the prevention of lightning disasters, theoretically speaking, the method of erecting lightning wires can meet the needs. However, we should also strengthen the docking price, which will increase the inspection and maintenance of devices, reduce the grounding resistance of towers and grounding devices, and attach great importance to the poor grounding of transmission lines (including main transformers)

2 pollution flashover fault causes and anti pollution measures

2.1 pollution flashover fault causes

when various pollution substances, such as dust, soot, chemical dust and salt, are attached to the surface of transmission line insulator, under certain humidity conditions, such as fog, frost or light rain, the pollution substances dissolve in water to form an electrolyte covering film, or when chemical gas containing conductive properties surrounds the insulator, Will greatly reduce the insulation performance of insulators, increase the leakage current on the surface of insulators, cause insulator flashover, and cause pollution flashover fault of transmission lines

Karamay area is generally not prone to pollution flashover fault of transmission lines due to dry climate, but there is still a great possibility of pollution flashover in some sections. For example, the 110kV Kelian line is just located on the downwind side of the cooling tower of the thermal power plant and is close to Karamay Petrochemical plant. The line insulators are eroded by the water vapor emitted by the cooling tower and the chemical dust scattered by the petrochemical plant all the year round. In winter, most of the line insulators are covered with ice, and the degree of ice coating is even serious to the extent that a string of ice pillars extend from the cross arm and hang on the umbrella skirt of the insulator, less than 20cm away from the charged body, It may cause line pollution flashover at any time

2.2 preventive measures

after replacing the straight pole line insulator (disc insulator) of Ke Lian line with synthetic rubber insulator with strong antifouling ability, serious icing has not been found in this section at present. In addition, for the pollution flashover of the line, preventive measures such as regularly cleaning the insulator or coating the surface of the insulator with antifouling paint (such as silicone grease, silicone oil, paraffin) can also be taken

3 insulator deterioration fault causes and preventive measures

3.1 causes of insulator performance degradation

in this area, insulator deterioration mostly occurs on 6, 10kV lines. According to the on-site inspection results, it is found that the main reasons for the deterioration of insulator performance are:

(1) the porcelain parts are roasted poorly, and the drying shrinkage of cement adhesive is large, resulting in the voids and moisture absorption of porcelain parts

(2) internal stress caused by uneven forming pressure and poor cooling of porcelain body, and internal stress caused by the difference of thermal expansion coefficient of porcelain body, cement and fittings, resulting in cracks in porcelain body

(3) the trace moisture in cement has repeatedly frozen and melted in the aluminum alloy medium and thick plates produced by the first production line in the natural environment, which has deteriorated the cement

(4) the surface of porcelain body is damaged by transportation, construction or pollution flashover, and the insulator is finally damaged due to the stress caused by climate change or conductor vibration; The unqualified insulator will damage the porcelain body, greatly reduce the mechanical strength of the steel foot, and even cause the steel foot to fall off

3.2 preventive measures

(1) strengthen the quality inspection before installation to prevent the damaged insulator from being put into operation. If necessary, the existing hydraulic safety testing machine in the line work area can be used to spot check the mechanical strength of the steel leg of the insulator

(2) the insulators in operation shall be tested regularly, and the unqualified insulators detected shall be replaced in time

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