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

Patent metadata

Field	Value
Publication number	US-9599653-B2
Application number	US-201214368677-A
Country	US
Kind code	B2
Filing date	Dec 26, 2012
Priority date	Dec 26, 2011
Publication date	Mar 21, 2017
Grant date	Mar 21, 2017

Abstract

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 (D 1 ), or a discharge of high energy (D 2 ) using the calculated composition ratios of C2H2/C2H4 and C2H4/C2H6.

First claim

The invention claimed is:

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 (D 1 ), or a high energy discharge (D 2 ) 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.

2. The method as claimed in claim 1 , wherein the third step comprises:
presetting CH4/H2 and C2H2/C2H4, which are indicated depending on each of the electric fault and the thermal fault in each of a plurality of oil-immersed transformers of which a type of the internal fault is known, as the first x and y coordinates on the first xy-plane; and
classifying a whole region of the first xy-plane into the electric fault (E) and the thermal fault (T) by using the plurality of the first x and y coordinates which are set,
wherein it is determined whether the internal fault is the electric fault (T) or the thermal fault (E) by using a region corresponding to the plural coordinates for CH4/H2 and C2H2/C2H4 which are calculated in the second step.

3. The method as claimed in claim 1 , wherein the fourth step comprises:
setting C2H2/C2H4 and C2H4/C2H6, which are indicated depending on each of the partial discharge (PD), the high energy discharge (D 1 ), and the low energy discharge (D 2 ) in each of a plurality of oil-immersed transformers in which the electric fault occurs, as x and y coordinates on a second xy-plane; and
classifying a whole region of the second xy-plane into the partial discharge (PD), the low energy discharge (D 1 ), and the high energy discharge (D 2 ) by using the plurality of x and y coordinates which are set,
wherein it is determined whether the internal fault is the partial discharge (PD), the low energy discharge (D 1 ), or the high energy discharge (D 2 ), by using the region corresponding to the plural coordinates for C2H2/C2H4 and C2H4/C2H6 which are calculated in the second step.

4. The method as claimed in claim 1 , further comprising: a fifth step of determining whether the internal fault is the first thermal fault (t<300° C.) (T1), the second thermal fault (300° C.<t<700° C.)(T 2 ), or the third thermal fault (t>700° C.) (T3), by using C2H4/C2H6 and C2H4/CH4 which are calculated, if the internal fault is the thermal fault (T) as a result of the determination in the third step; and
a sixth step of determining whether the internal fault is the second thermal fault (300° C.<t<700° C.)(T 2 ) or the third thermal fault (t>700° C.)(T 3 ), by using C2H2/C2H4 and C2H4/C2H6, if the internal fault is the second thermal fault (300° C.<t<700° C.)(T 2 ) or the third thermal fault (t>700° C.)(T 3 ) as a result of the determination in the fifth step.

5. The method as claimed in claim 4 , wherein the fifth step comprises:
presetting C2H4/C2H6 and C2H4/CH4, which are indicated depending on the first thermal fault (t<300° C.), the second thermal fault (300° C.<t<700° C.)(T 2 ), or the third thermal fault (t>700° C.)(T 3 ) in each of the plurality of oil-immersed transformers of which the thermal fault occurs, as third x and y coordinates on a third xy-plane; and
classifying a whole region of the third xy-plane a first thermal region (T 1 ), a second thermal fault, or a third thermal fault by using the third x and y coordinates which are set,
wherein it is determined whether the internal fault is the first thermal fault (T 1 ), the second thermal fault, or the third thermal fault, by using a region corresponding to the plural coordinates for C2H4/C2H6 and C2H4/CH4 which are calculated in the second step.

6. The method as claimed in claim 5 , wherein the sixth step comprises:
presetting C2H4/C2H4 and C2H4/C2H6, which are indicated depending on the second thermal fault (300° C.<t<700° C.)(T 2 ) and the third thermal fault (t>700° C.)(T 3 ) in each of the plurality of oil-immersed transformers of which a type of the internal faults is known, as fourth x and y coordinates on the fourth xy-plane; and
classifying a whole region of the fourth xy-plane into the second thermal fault (T 2 ) region and the third thermal fault (T 3 ) region by using the fourth x and y coordinates which are set,
wherein it is determined whether the internal fault is the second thermal fault or the third thermal fault, by using a region corresponding to the plural coordinates for C2H2/C2H4 and C2H4/C2H6 which are calculated in the second step.

7. A method of diagnosing an internal fault of an oil-immersed transformer through a composition ratio of a dissolved gas in oil, the method comprising:
a first step of calculating composition ratios of CH4/H2, C2H2/C2H4, C2H4/C2H6, and C2H4/CH4 of dissolved gases after extracting the dissolved gases from each of a plurality of oil-immersed transformers of which the internal fault is known;
a second step of classifying a whole region of the first xy-plane into an electrical fault (E) and a thermal fault (T) by using a plurality of x and y coordinates after setting CH4/H2 and C2H2/C2H4, which are indicated depending on each of the electrical fault (E) and the thermal fault (T) among the internal faults, as the x and y coordinates on the first xy-plane;
a third step of classifying a whole region of a second xy-plane into a partial discharge (PD) region, a low energy discharge (D 1 ) region, and a high energy discharge (D 2 ) region by using the plural x and y coordinates after setting C2H2/C2H4and C2H4/C2H6, which are indicated depending on each of a partial discharge (PD), a low energy discharge (D 1 ), and a high energy discharge (D 2 ) among the internal faults, as the x and y coordinates on the second xy-plane;
a fourth step of classifying a whole region of a third xy-plane into a first thermal fault (T 1 ) region, a second thermal fault (T 2 ) region, and a third thermal fault (T 3 ) region after setting C2H4/C2H6and C2H4/CH4, which are indicated depending on each of a first thermal fault (t<300° C.)(T 1 ), a second thermal fault (300° C.<t<700° C.)(T 3 ), and a third thermal fault (t>700° C.)(T 3 ) of the thermal fault (T), as the x and y coordinates on the third xy-plane;
a fifth step of classifying a whole region of a fourth xy-plane into the

Assignees

• Hyosung Corp

Inventors

• Kim Sung-Wook
• Seo Hwang-Dong
• Kim Sung-Jik

Classifications

• G01R31/62 Primary

  Testing of transformers · CPC title

• G01N33/2841 Primary

  Gas in oils, e.g. hydrogen in insulating oils · CPC title

• G01N33/24

  Earth materials (G01N33/42 takes precedence) · CPC title

• G01N33/2025

  Gaseous constituents · CPC title

• G01N33/0004

  Gaseous mixtures, e.g. polluted air · CPC title