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!

Identifying/Isolating Sources of Voltage Sags Quickly

Recently I’ve attended a Power Quality (PQ) Seminar organised by Fluke in Manchester, UK as part of their Fluke 430series PQ Analyzer promotion campaign. During this seminar, they talked about power quality problems, their experiences in identifying those using Fluke monitors, how they helped customers solve these problems, gave us an hand-on experience in using PQ monitor equipment.

The following are the two quick tips recommended during this seminar on how to identify the source of voltage sags.

• If voltage sags coincides with depression in current flow into the customer’s feeder then the source of voltage sag source is external to customer’s facility;
• However if the voltage sag coincides with increase in load current flow into the customer’s supply feeder then the source of voltage sags problem is within the customer’s facility.

Principle:

Typical causes of voltage sags due to external utility are faults and switching on/off of large loads (induction motors etc.) at the utility network or at the neighbouring customer’s facility connected to the point of connection (or supply) as our customer. In this case, the cause of voltage sags is due to large voltage drops across circuits caused by large currents drawn during system events (faults, sudden connection of large load etc), and our customer’s facility as a result will receive reduced current. Therefore for external causes of voltage sags, the voltage sags coincide with depression current consumption in to our customer’s feeders.

On the other hand, the same system events (faults etc.) when arise within our customer’s facility, then large currents are drawn by customer’s supply feeders causing voltage to depress, and thereby having increased current consumption coinciding with voltage sags.

The above voltage sag source detection logic is simple, yet has hugely practical implication in isolating the problem quickly.

There is also considerable amount online resource available on various power monitoring and application aspects at the Fluke UK Application Notes section. Hope you will learn something new here having thoughts like: ‘Hey! That’s interest and useful, I didn’t know that before.’, or feel good at heart thinking ‘Ah! I knew that and I could teach some folks perhaps’. However you feel, hope you will have a good time perusing through them.

Have fun!

Alex McEahern: Use all Senses Except Taste to Identify PQ Problems

I have had an opportunity to meet Alex McEahern and talk to him during his visit and meeting with my PhD academic supervisor Prof. J V Milanovic. It was a pleasure talking and listening to his ideas, work and his company ‘Power Standards Lab’.

He developed an  interactive software teaching toy for young engineers like to me to understand and identify various  power quality problems. Links: Power Quality Teaching Toy; Online PQ tutorials; and Power Standard Lab.

Power Quality Working Groups

Power systems research and application engineers, depending on their ‘point-of-view’, are broadly divided into four categories:

• Those that take a utility’s point of view;
• Those that take end-user’s point of view;
• Equipment manufacturer’s and third party solutions and services (consultants, experts etc.) provider’s point of view;
• And finally those (e.g. PQ related standards, working groups, regulators, university PQ projects that are funded by independent bodies or institutes etc.) who see the big picture and bring equilibrium among the above three perspectives.

Each of first three groups, i.e. utility (Group 1), customer (Group 2) and equipment manufacturer/consultant (Group 3), have valuable insight, expertise, and know how in their respective representing group. These three representing groups usually have biased view on various PQ issues. Some of these include: ‘who is responsible for PQ problems?’ and ‘who should and how much each should contribute towards problem solution?’ However, it is this biased view that makes them a vital constituent in maintaining a fair share of involved party’s (utility, end-user etc.) PQ improvement responsibility. The final or the fourth group, although seeks to see the big picture, taking a collective view of all three groups preceding it, may lack in depth knowledge of particular PQ problems each of other groups are handling.

When PQ standards are written, a working group is set up, which at best tries to include at least one delegate or more, representing each of these groups to review and to push forward a new standard that is fairly acceptable for all concerned parties.

A comprehensive study, nevertheless, should aim to develop a methodology that includes tools/modules to bring customized voltage disturbance assessment for both utilities and industrial customers, such that results obtained from the tool could be well beneficial for equipment manufacturers to access PQ market potential and to establish specification range of their equipment to meet a specific customer’s or utility’s voltage disturbance immunity criteria. The objective should be to present a tool that brings interaction and integration of data consensus from utilities, customers and equipment manufacturers, thus enabling faster optimization of PQ improvement through iterative interactions of these parties (utilities, customers and equipment manufacturers).

Power Systems Harmonics

G. J. Wakileh, Power Systems Harmonics: Fundamentals, Analysis and Filter Design, 1ed, Springer, 2001.

Power Quality in Electrical Systems

A. Kusko, M. T. Thompson, Power Quality in Electrical Systems, 1ed, McGraw Hill, 2007.

Handbook of Power Quality

A. Baggini, Handbook of Power Quality, Willey, 2008.

Power Quality in Power Systems and Electrical Machines

E. F. Fuchs, M. A. S. Masoum, Power Quality in Power Systems and Electrical Machines, London: Elsevier Academic Press, 2008.

Power Quality Primer

B. Kennedy, Power Quality Primer, New York: McGraw Hill, 2000.