Self-adaptive partial-discharge monitoring method and device for sampling frequency

Abstract

The invention relates to a self-adaptive partial-discharge monitoring method and device for a sampling frequency. The method comprises the following steps: (1), detecting a UHF (Ultra High Frequency) signal; (2), achieving low-frequency sampling of the detected UHF signal, and meanwhile, judging whether a maximal amplitude value of the detected discharge voltage is continuously greater than a set threshold value, if no, proceeding low-frequency sampling, and if yes, carrying out high-frequency sampling, wherein low-frequency sampling information of at least 50 former continuous periods is saved while the high-frequency sampling is started; and (3), allowing the duration of the high-frequency sampling to be longer than a power frequency period, saving the high-frequency sampling information and terminating the sampling. The sampling method provided by the invention improves the precision of a monitoring system, the fault type correct identification rate and the economical efficiency.

Description

technical field [0001] The invention relates to a method and a device for partial discharge sampling in the field of intelligent substations. Background technique [0002] Partial discharge is a non-penetrating discharge phenomenon caused by local defects (such as air bubbles, cracks, suspended metal particles and electrode burrs, etc.) in the insulating medium caused by equipment during manufacturing and operation. An important symptom of insulation cracking in long-term operation. If the insulation structure of electrical equipment sustains partial discharge for a long time, the dielectric properties of the insulation may be severely damaged, which may eventually lead to catastrophic failure of the electrical equipment. Partial discharge detection can effectively reflect the insulation fault inside the transformer, and the partial discharge monitoring of high-voltage equipment has become one of the important contents of high-voltage equipment condition monitoring. The UH...

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Problems solved by technology

[0003] In the sampling processing of partial discharge signals, two methods are commonly used at present. One is the 2MHz high-frequency sampling method. Due to the high sampling rate, this method has a large amount of sampled data in a simple frequency cycle and a high degree of signal restoration. The value can accurately determine the sampling intensity and the type of discharge fault, but due to the large amount of data, the corresponding storage data capacity is limited, the number of signal cycles is small, and the effect of statistical analysis using multi-cycle information is not good; the other method uses 6.4kHz low-frequency sampling method, the sampling accuracy and data restoration degree of this method are poor, but due to the small amount of sampled data in a single power frequency cycle, the same size of storage space can contain UHF signals of multiple power frequency cycles, which is conducive to statistics Analysis, South Korea's partial discharge often adopts this method

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