Abstract—Harmonic plays a vital role in electrical power system and also creates lots of problems in the power system like interruptions, sagging and switching transients etc. so it is important to reduce the problems of total harmonic distortion in AC supply system. To overcome these problems we used different techniques. This paper described the concepts of using the different combination of loads such that resistive-inductive (RL), resistive-capacitive (RC) and resistive-inductive-capacitive (RLC) are taken. The values of inductance ranging from 1073.0mH to 729.5mH, capacitors 2.5μF, 15μF, 50μF, resistance 36Ω and compare them all loads. Harmonic distortions in the input and output of the system are calculated. The input and output voltage waveforms are recorded for all combination of loads by using signal recording software having duration of 1s. We designed the algorithm for calculating the value of Total Harmonic Distortion (THD) in the supply system. Reduction in the THD was observed in the given IGBT based power system.