Development of dissolved gas analysis(DGA) expert system using new diagnostic algorithm for oil-immersed transformers

Abstract

Dissolved gas analysis(DGA) is one of the most widely used diagnostic tools to detect and evaluate faults in power transformers for a long time. IEEE Guide C57.104 and IEC Publication 60599 recommend several DGA diagnostic methods used for utilities and most of them are available to classify the different types of faults using gas ratios or %gas. However, the task of DGA interpretation is not easy because they often can provide unresolved diagnoses and wrong diagnoses. Therefore, it is necessary to develop new method for gas interpretation that has higher accuracy and more reliable diagnoses. This paper proposes new diagnostic methods to classify six types of faults specified in IEEE Guide C57.104 and IEC Publication 60599 using gas ratio and relative % of combustible gases (H 2 , C 2 H 2 , C 2 H 4 , C 2 H 6 and CH 4 ). And accuracy of the proposed diagnosis methods was verified using IEC TC10 and related databases. Also, on-line DGA diagnostic system, HiDGA(Hyosung intelligent Dissolved Gas Analysis), that is possible to continuously monitor transformer in service is developed and it is possible to identify faults of transformer by visual inspection using new diagnostic method that applied to diagnostic HMI(Human Machine Interface).

A review on fault detection and condition monitoring of power transformer

“…Among different chemical techniques for predictive maintenance, the Dissolved Gas Analysis (DGA) has been considered as the single first most powerful techniques for transformer fault detection and still has been used (Duval, 2003;Kelly, 1980;Shintemirov et al, 2009;Sun et al, 2012b;Ashkezari et al, 2011). It has been at the forefront of most progressive utilities monitoring strategy for the last four decades (Saha, 2003;Kim et al, 2012;Gómez, 2014;Kelly, 1980).…”

“…Rogers has better accuracy among the key gas, doernenburg and roger's ratio. The only drawback with this method that few bunches of gases don't fit into the predefined range of values when computed and thus the fault type can't be clarified (Kim, 2012).…”

Parametric identification of fuzzy model for power transformer based on real operation data

“…In the world practice of power companies, the DGA in oil is used as the main type of diagnostics, which revealed most faults and it is now used as the basic method for evaluating the technical condition of power transformers [22]. However, the problem of interpreting the DGA results is complicated, since it is not always possible to detect damage in power transformers [23].…”

A Hybrid machine‐learning method for oil‐immersed power transformer fault diagnosis

“…Currently, the gas dissolved analysis (DGA) method has been widely recognized as one of the effective methods for detecting faults in power transformers . The content and concentration of special dissolved gases in the transformer insulating oil can reflect the state of the transformer.…”