Interpretation of Frequency Response Analysis for Fault Detection in Power Transformers

Salem Mgammal Al-Ameri,Ali A. Salem,Mohd Fairouz Mohd Yousof,Mohamed I. Mosaad,A. Abu Siada,Muhammad Saufi Kamarudin

doi:10.3390/app11072923

Abstract

Frequency response analysis (FRA) is a method of monitoring a power transformer’s mechanical integrity. However, identifying the type of fault and its severity by comparing measured responses is still challenging and mostly relies on personnel expertise. This paper is taking one step forward to standardize the FRA interpretation process by proposing guidelines based on various international standards and FRA case studies. In this study, the FRA signature is divided into three regions: low-, mid- and high-frequency regions. The deviation from the fingerprint signature for various faults is classified into small, large, and no variations, based on the calculation of the correlation coefficient. The proposed guidelines are developed based on the frequency regions, and the level of variation is represented using a simple arrow method to simplify the interpretation process. A case study is conducted on a three-phase 11/0.433 kV, 500 kVA distribution transformer with a short circuit winding fault to validate the proposed guidelines.

Highlights

Frequency response analysis (FRA) is the most reliable diagnostic tool for detecting winding and core deformation in power transformers [1]
FRA is a reliable tool for the assessment of power transformer mechanical integrity
This paper proposes an easy-to-use flowchart and characteristic table as a guideline to facilitate the identification and quantification of FRA signatures

Summary

Introduction

Frequency response analysis (FRA) is the most reliable diagnostic tool for detecting winding and core deformation in power transformers [1] Such deformations affect the equivalent, inductive, and capacitive components of the transformer, thereby altering its frequency response. In case the reference signature is not available, a comparison with the response of other phases of the same transformer or with the response of an identical transformer (sister unit) is conducted. International standards such as the IEEE standard [1], the CIGRE standard [2], the IEC standard [3], and the DL/T

Objectives

Methods

Conclusion