Method for online monitoring of fault of insulator based on thermal infrared imaging technology

Abstract

The invention discloses a method for the online monitoring of a fault of an insulator based on the thermal infrared imaging technology, and the method comprises the steps: employing a rectangular frame point selection method for a steel cap part, and employing line point selection for an insulator string part for coordinate and temperature conversion; obtaining four types of temperature parameter characteristic quantities through employing an insulator fault detection algorithm: a low-value insulator characteristic quantity, a zero-value insulator characteristic quantity, an insulator pollution accumulation characteristic quantity and an insulator damage characteristic quantity; selecting two three-layer PNN probability neural networks for the feature level fusion of the steel cap part and the insulator string part through combining with environment temperature, humidity and pollution conditions; giving a local information fusion judgment result; and submitting the result to a decision-making level for global decision marking. The method improves the precision of an information fusion model, clearly divides a fault and a non-fault, reduces the misjudgment rate, employs the plurality of characteristic quantities for monitoring, and combines the data of the plurality of characteristic quantities and the insulator fault judgment model to carry out the fault discrimination. Therefore, the method improves the reliability of the monitoring data.

Description

technical field [0001] The invention belongs to the field of operation state maintenance of power transmission and transformation equipment, in particular to an online monitoring method for insulator faults based on thermal infrared imaging technology. Background technique [0002] As a kind of high-voltage insulation control, it transmits power from fixed self-power plants to substations, and then through high-voltage transmission lines such as high-voltage bus branches at all levels, and finally reaches power consumption units at all levels. Insulator strings are everywhere. However, insulator strings are also used as a common insulation control, and are used in various harsh environments outside, and are always withstood the test of nature. First, during operation, when the insulator strings are exposed to areas with severe air pollution, they are extremely vulnerable to dirt adhering to the surface of the insulators. The worst result is that the leakage current on the ou...

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Problems solved by technology

According to the development history, the following insulator fault detection technologies have been applied to the grid insulator fault diagnosis process. There are the following methods: microwave radiation detection method to detect the pollution level of insulators according to the radiation characteristics of the microwave section, remote operation , but it is affected by weather temperature and humidity, microwave incident angle and antenna beam; ultrasonic detection method is used to diagnose cracked insulators according to the reflection of sound waves in the gap of the fault layer and the waveform conversion law. It has high sensitivity and low cost, but is limited by its own coupling and attenuation characteristics. As well as the influence of temperature factors, it is only effective for cracked insulators; the radio wave diagnosis method mainly detects the radio waves emitted by the problem insulators, and judges according to the characteristics of the radio waves. ;Laser Doppler detection method is used to detect cracked insulators. By using laser to vibrate the insulator, it can be compared with good insulators. The accuracy is high, but the device is heavy and difficult to move; When a conduction fault occurs, the electric field intensity is reduced, and the distribution curve of the electric field is distorted, and the fault location can be found by comparing the position of the insulator, which is not easily affected by external interference, but it needs to be detected by climbing a pole, and the position of some insulator sheds cannot be detected; The leakage current detection method detects the corresponding resistance value according to the leakage current generated by the inferior insulator due to the problem of resistance reduction, and can judge the pollution degree of the insulator based on this, and the insulation resistance can further infer whether there are low-value zero-value insulators , the precision of the device is high, but the cost is expensive, and it is affected by weather factors such as temperature and humidity; the pulse current detection method is processed by digital processing technology to obtain the pulse amplitude and frequency, and then to know the operating status of the insulator, mainly to detect the insulation status of the insulator, The accuracy is high, but the operation is difficult; the ultraviolet imaging detection method is based on the ultraviolet rays emitted by the defective insulator during the partial discharge process to infer the degree of discharge of the insulator and the emission position to find out the location of the fault defect of the insulator; Partial discharge or leakage current caused by cracking or insulation resistance reduction faults cause local heating abnormalities, and then provide fault diagnosis information such as whether the insulator has a low zero value, internal or surface cracks, and pollution levels, etc.

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