Sweep frequency response analysis (SFRA) results interpretation using cross correlation coefficient method for distribution transformer

Mohd Safwan , Mohamad (2014) Sweep frequency response analysis (SFRA) results interpretation using cross correlation coefficient method for distribution transformer. Project Report. UTeM. (Submitted)

Text Sweep Frequency Response Analysis (SFRA) Results Interpretation using Cross Correlation Coefficient Method for Distribution Transformer 24pages.pdf Download (487kB)

Abstract

The distribution transformers in Malaysia are very crucial parts of the power system grid. Therefore, asset management is a must in order to sustain the distribution transformer services. Recently, one of the advanced techniques of asset management in Tenaga Nasional Berhad (TNB) is Frequency Response Analysis (FRA). Its capability is compromised via monitoring winding displacement and other electrical faults. The FRA technique uses Sweep Frequency Response Analysis (SFRA) to measure and evaluate the condition of the transformer whether it is healthy or not. Previously, the interpretation of SFRA results is used based on worldwide research finding as a guideline. Recently in 2013, IEEE Std C57. 149 2012 (IEEE Guide for the Application and Interpretation of Frequency Response Analysis for Oil-Immersed Transformer) is established for interpreting SFRA measurement result data. From the IEEE Standard C57.149 2012, four frequency sub-band is discovered: Region 1 (20 Hz – 10 kHz), Region 2 (5 kHz – 100 kHz), Region 3 (50 kHz – 1 MHz) and Region 4 (> 1 MHz). Statistical technique is one technique used to analyze the data and the method to evaluate the condition of the transformer is done using Cross Correlation Coefficient (CCF) method. Ten transformers are used as the test’s subject and the finding from the testing is two from the transformers is in unhealthy condition while others are not. The CCF value 90% and above evaluated as a healthy condition and below than 90% evaluated as unhealthy condition of transformer. PPU Seksyen 23 T2 and PPU Kelibang T2 are obviously indicated in unhealthy condition and other transformer still operates as usual.

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