Virtual Harmonic Analyser – harmonic analysis and estimation of THD using LabVIEW

Abstract

At this modern industrial world 90% of the Electrical supply is flown through Power electronic converters (nonlinear loads) produces harmonics, which are disturbing the other equipments connected in the same supply. Hence it is necessary to measure the harmonic components to estimate their effect. The separation of various frequency components with respect to the fundamental frequency is carried out to calculate the Total Harmonic Distortion (THD) which is useful to design suitable filters to remove the harmonics in the signal. This paper proposes a novel method to analyse the harmonic contents in a non-sinusoidal signal. The proposed method is carried out using ‘Virtual Instrumentation’ concept with the help of Lab VIEW software and low cost DAQ card is designed with the help of PIC microcontroller. A Virtual Harmonic Analyser (VHA) is developed to detect the fundamental frequency of the given non-sinusoidal signal, to separate the different frequency components and to compute the THD. And also, it provides remote accessibility to many users through web. The performance of the proposed VHA is comparable to that of a hardware based analyser.