Harmonics, Inter-harmonics, and Sub-harmonics

I knew instinctively what these terms meant, but I never knew the true harmonic terminology until I attended a harmonics training training course recently at The University of Manchester. So if you didn’t know like I did, here’s enlightenment for both of us.

Harmonics: A sinusoidal component of a periodic wave having a frequency that is an integer multiple of the fundamental frequency.

Inter-harmonics: Components with frequencies between two consecutive harmonics or those components whose frequencies are not integer multiples of the fundamental power frequency.

Sub-harmonics: A special subset of interharmonics that have frequency values that are less than that of the fundamental frequency.

Table below illustrate their usage with examples for a 50Hz system.

Note: Information presented here and illustration was taken from the Prof. A. Testa’s power quality course lecture held at the University of Manchester on the 26th Jan 2010. Some information was obtained through email exchange between Prof. V. Katic and I following my attendance of the course. Thank you Gentlemen.

Power Quality Course Review

Recently I attended harmonics part of the power quality course organised by The University of Manchester’s power systems group on the 26th Jan 2010. I totally enjoyed the lectures. The harmonics part of course covered basic concepts, math behind core concepts (Fourier transform etc.), indices, various harmonic standards, some research challenges associated with harmonic analysis and finally very brief information on mitigation solutions. The bottom line from the presenters on the harmonics was that the power systems harmonic topic is still at it’s nascent state, and there will be continued focus and research in this field. Thats good news for potentials PhD students and researchers in this field.

The course had four sections, two sections each by Prof. A. Testa and Prof. V. Katic, each presenting alternatively. Prof. A. Testa lectures were more academic: harmonic concepts, math, analysis methodologies, harmonic problems, harmonics research challenges and focus. While Prof. V. Katic lectures focused on the practicalities in dealing with harmonic problems, harmonic standards and how these standards come up with harmonic limit numbers, harmonics measurement and mitigation. Both presenters were brilliant! The lecture content and presenters were most close what I need to brush my knowledge about and learn harmonic concepts.

I will touch on some of the course material I learnt and found interesting in my coming blogs.

Take care!

Power Quality Course at University of Manchester

University of Manchester’s power systems group is organising a power quality course between the 25th – 27th January 2010. The course seeks to provide attendees a thorough understanding of major Power Quality issues facing customers and electrical power system operators with substantial distributed generation penetration. The most interesting part of this course will be the presenters’ list, these are some of the finest academics and researchers in the field of Power Quality.

Download the brochure. The document includes course scope, schedule, and presenter biographies.

I have been a student at the university, completing a masters and a doctoral degree, between 2003-2008. Since leaving school  I’ve been in contact with the power system group staff and colleagues at the university. This comes as a surprise to me seeing the group organising this specialised Power Quality course inviting renowned researchers in this field.  Not that the group has’t invited people or has not been visited by top researchers before, but never to my knowledge was a course for 3days like this one. Well done Power Systems group.

Hope the attendees will find it useful. Good luck!