Method for diagnosing internal fault of oil-immersed transformer through composition ratio of dissolved gas in oil

摘要

The present invention relates to a method for diagnosing an internal fault of an oil-immersed transformer by analyzing the composition ratio of dissolved gas in oil that is caused when an internal fault of the oil-immersed transformer occurs. According to the present invention, a method for diagnosing an internal fault of an oil-immersed tranformer by extracting and analyzing dissolved gas in oil from the oil-immersed transformer for which an internal fault is to be diagnosed comprises: a first step of calculating the composition ratio of each of CH4/H2, C2H2/C2H4, C2H4, C2H4/C2H6, and C2H4/CH4 from among the extracted dissolved gas in oil; a second step of determining whether the internal fault is an electrical fault or a thermal fault using the calculated composition ratios of CH4/H2 and C2H2/C2H4; and a third step of determining, if said internal fault is determined to be an electrical fault in the second step, whether the electrical fault is a partial discharge (PD), a discharge of low energy (D1), or a discharge of high energy (D2) using the calculated composition ratios of C2H2/C2H4 and C2H4/C2H6.

主权项

1. A method for diagnosing an internal fault of an oil-immersed transformer by extracting and analyzing dissolved gases from the oil-immersed transformer of which the internal fault is able to be diagnosed, the method comprising:
a first step of presetting ratio of CH4/H2 and C2H2/C2H4, which are indicated depending on the types of the internal faults respectively in each oil-immersed transformer of which the types of the internal faults are already known, as first x and y coordinates on a first xy-plane, presetting ratio of C2H2 /C2H4 and C2H4 /C2H6, which are indicated depending on the types of the internal faults respectively in the oil-immersed transformer, as second x and y coordinates on a second xy-plane, and classifying the first and second xy-planes into fault region corresponding to the type of the internal faults by using the first and second x and y coordinates which are preset on the first and second xy-planes; a second step of calculating composition ratios of CH4/H2, C2H2/C2H4, C2H4/C2H6, and C2H4/CH4 among the dissolved gases which are extracted from the oil-immersed transformer of which the internal fault is able to be diagnosed; a third step of determining whether the internal fault is an electrical fault (E) or a thermal fault (T) by making the calculated ratios of CH4/H2 and C2H2/C2H4 to correspond to the fault region corresponding to the type of the internal faults on the first xy-plane which is classified at the first step; and a fourth step of determining whether the internal fault is a partial discharge (PD), a low energy discharge (D1), or a high energy discharge (D2) by making the calculated ratios of C2H2/C2H4 and C2H4/C2H6 to the fault region corresponding to the type of the internal faults on the second xy-plane which is classified at the first step, if the internal fault is the electrical fault (E) as a result of the determination in the third step.