Investigation on the relationship between Transmission Level Transformer Health Indices and Load Readings from SCADA in TNB

Abstract

Transformer Asset Health Index is used by asset managers as a numerical indicator to generalized asset condition. However, conventional Asset Health Index requires input from various diagnostics results. Online diagnostic results are possible and could provide on-demand calculation of Asset Health Index but requires utilities to invest in expansive online condition monitoring system. This paper investigates the relationship of conventional Transformer Health Indices against load readings obtained from SCADA such as transformer active and reactive power. Using past series of 10 minutes samples of 3-phase active and reactive power readings of a transformer, the average readings and the spread of those readings are calculated and using ordinary least squares analysis, relationship between transformer health index, Criticality Index and Transformer Health Assessment published in 2014 are compared against average active power, average reactive power, the standard deviation of active power and the standard deviation of reactive power recorded in 2013. Using a sample of 43 transformers, the results show that there are relationships found between Transformers Health Indices and transformers load readings from SCADA with significant fit. It is concluded that there is a significant relationship between Transformer Health Indices and Transformer load readings and further investigation should be done in order to see if it is feasible to use data from SCADA as equivalent conventional Asset Health Index since there is a significant relationship among the variables that contributes towards Transformer Health Indices value.