Power quality: a growing concern

Andy Sagl - Product manager

The modern power distribution grid is changing rapidly and these changes can be expected to have an impact on power quality, which is the concept of powering sensitive equipment in a manner that is suitable to the operation of that equipment. In the short term at least, the impact is likely to be negative, with power quality problems becoming more rather than less troublesome.

The power grid is being forced to change as the result of not one but many simultaneous developments. These include the growing need to connect green energy sources, such as wind and solar power, and the steady reduction in the number of traditional bulk generation plants that rely on fossil fuels as their energy source. Loads on the grid are also changing, with new technologies like electric vehicles leading to an even greater demand for power and a shift in the hours of peak demand. To help address these changes, smart-grid technology, designed to make the grid more efficient and more flexible, is being introduced.

It might be tempting to think that the spread of smart-grid technology will alleviate power quality problems, with a consequent reduction in the need for power quality investigations. Unfortunately, this isn’t the case. A primary objective of the smart grid is to increase the reliability of power delivery – it is unlikely to have any significant impact on the quality of the power being delivered. In fact, the new types of loads and sources continually being added to the grid will inevitably create new power quality challenges.

Some of the most common power system fluctuations impacting power quality include under- and over-voltage, dips (sags) and swells, transients, unbalance, flicker, harmonics and rapid voltage changes. To help readers refresh their understanding of power quality and to stay up to date with the latest thinking, we are currently preparing a series of articles, starting with the fundamentals of PQ and progressing to topics such as what is a Class A recording, transient and harmonic impacts on motors and transformers, energy fundamentals, and the truth about energy saving devices. The first of these timely and well informed series of articles will appear in a future edition of Electrical Tester and will look at the foregoing types of power system fluctuations, explaining why and how they occur, examining the effects they have on the power distribution network and on loads, and discussing how they can be measured and evaluated.