Method and system of determining transformer direct current biasing state with noise detection

Abstract

The invention discloses a method and system of determining a transformer direct current biasing state with noise detection. The method comprises steps of detecting a noise signal at an assigned noise detection point of a transformer, and extracting a direct current biasing noise feature parameter according to the noise signal; and comparing the direct current biasing noise feature parameter with a preset direct current biasing noise feature parameter threshold, determining the transformer in a direct current biasing state if the direct current biasing noise feature parameter exceeds the direct current biasing noise feature parameter threshold, and otherwise, determining the transformer in a normal state. The system comprises a corresponding noise detection unit, a noise feature parameter extraction unit and a direct current biasing state determination unit. Equipment operation states are not needed to be changed, contact with live equipment is not required, the detection safety is high, and advantages of safety, accuracy, zero misjudgment, independence from sense organ determination and staff operation experience, convenient testing, and manpower and material saving are achieved.

Description

technical field [0001] The invention relates to the technical field of electric power safety monitoring, in particular to a method and system for judging the DC bias state of a transformer by using noise detection. Background technique [0002] When the UHV converter station operates in a single-pole ground loop mode, DC current flows into the AC transformer through the grounded neutral point, causing DC bias problems. When DC bias occurs, the excitation current of the transformer will be distorted and a large number of harmonics will be generated, and the core magnetism will be saturated, causing the noise and vibration of the transformer to increase, which seriously threatens the safe operation of the transformer. [0003] In order to diagnose the DC bias problem, the main methods currently used include the neutral point current detection method on the high voltage side of the transformer and the noise detection method. The neutral point current detection method directly ...

AI Technical Summary

Problems solved by technology

The neutral point current detection method directly detects the neutral point DC, and the accuracy of judging the DC bias state is high, but before the detection, it is necessary to change the operation mode of the neutral point of the transformer, that is, to ground the neutral point of the main transformer to be detected The knife switch is opened and a Hall sensor is installed on the ground terminal, so the real-time performance and safety of detection are poor

The existing noise detection method uses a sound level meter to measure the sound pressure level of the transformer, and judges the DC bias state through the difference between the sound pressure level of the transformer before and after the DC bias. This method relies on sensory judgment and requires the staff to have rich operating experience. When the neutral point DC is small, it is easy to cause misjudgment

In addition, the existing detection methods all require staff to go to the site. Due to the large number and wide distribution of the affected substations, this method lacks flexibility and easily causes waste of human and material resources.

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