Transformer performance model under power quality environment

Abstract

The widespread use of static rectification and energy efficient equipment in end user loads result in a dramatic increase in harmonic content injection towards transformers connected to upstream power system. Now, due to modern developments, energy efficient equipment, such as compact fluorescent lamps are easily available. The use of energy efficient equipment increases rapidly in our country as saving of electrical energy is the main target of end users and also electric utility. Meanwhile, these types of equipment contribute to power quality problems such as harmonic distortion. The harmonic content generated by load causes the transformer to operate in higher power rating and may cause transformer operating failure in the long term. This work was initially started with experimentation of transformer performance analysis in the presence of harmonic events. The objective of this research is to develop the total harmonic distortion and efficiency model based on data analysis. Experimental tests are performed to obtain transformer parameter. Harmonic loads are modelled by utilizing the unique waveform characteristic of each individual harmonic load type through image processing and curve fitting methods. Harmonic current injection model has been proposed and applied using transformer model through the experimental parameter in MATLAB Simulink. The comparison between harmonic current injection model with the measured load in terms of true RMS current, apparent power, active power, true power factor and total harmonic distortion current have been done. An analysis has also been done on experimental data by comparing the efficiency of transformer with and without harmonic distortion on identical load type. The developed models for analysis of transformer efficiency with harmonic distortion indicate goodness of fit with R-square value close to 1 and Root Mean Square Error of less than 1.