Power Transformer Diagnosis Using FRA and Fuzzy Sets

Power transformer condition assessment is a very complex task but also of high priority for power system reliability. Several diagnosis techniques have been published in the field of transformer condition assessment, where some new techniques are used to assess winding and core condition, e.g. Frequency Response Analysis (FRA). FRA technique is a promising tool, since it is sensible to some minor winding deformations, which are very important when transformer condition is evaluated.Research advances in transformer diagnosis using FRA show some methods using mathematical indexes and frequency band definition for failure detection and interpretation, respectively. These methods show increasing sensitivity of the indexes when they are evaluated in suitable frequency bands. Also, failure interpretation strategy is focused on the relationship between failures and their influence on different frequency bands of the frequency response. However, a suitable method using FRA for failure detection and interpretation is still to be established. This paper presents a novel method for failure detection and interpretation using mathematic indexes and fuzzy sets.