What is Power Quality?

This is the very first episode of a blog series that could shed some light on energy efficiency, more specifically, on the efficiency of electrical equipment. So, if you are a maintenance/building/production manager, this one is for you. If (and only if) you want to lower energy usage and costs, of course.

Visualization meditation

Let’s try an exercise. Visualize a river. Yes, a river. Where the river is the electricity flow. Now visualize that the turbulence of the river is (really) the Power Quality. Go with the flow. The smoother the river flows, the better the Power Quality is. The turbulent the river flow, the worse the Power Quality is. Smooth is better. Smooth is the best. Even when it comes to heavy stuff like energy.

Understanding the Power of Power Quality

In order to understand Power Quality and quantify its strong influence on the overall Energy Performance and Operational Performance of an energy boundary, one must first define particular Power Quality Indices, as there are many reasons for increasing the turbulence of our river - i.e. electricity flow. That one is Cristian Gheorghiu, Energy Engineer, and Ph.D. Std. Teaching Assistant at University Politechnica of Bucharest. Maybe you know him from here, where he talks about, no surprise here, energy efficiency.

Total Harmonic Distortion

Power quality issues fall generally into some broad categories. Harmonic voltages and currents are introduced by a range of common electrical devices which distorts the AC waveform and increases power usage. By introducing harmonic filters or reactors, the harmonics are eliminated and the result is more efficient power usage and cost savings.

The Power Factor

Poor power factor refers to an excess of reactive power in the system. This reactive power does not perform any real work and as such is wasteful and costly. Power Factor Correction (PFC) reduces and can almost eliminate this reactive power, reduce energy costs and stop equipment overheating, nuisance tripping, and motor failure. Sorry, it’s not like X Factor.

Current and Voltage Unbalance

Voltage instability is in part a side effect of the high or low voltage electricity supply from the network. High voltage does not increase equipment power and is detrimental to equipment performance and longevity, and low voltage can cause brownouts and reduced productivity. Voltage optimization ensures the voltage supplied to the system is stable as required by the equipment on site.

Short and Long Term Flicker

One of the many aspects of power quality that can affect electricity users is voltage fluctuation that causes lights to flicker. Whenever the electrical load changes, the supply voltage is affected proportionately. Most people have seen this occur in their house; when the refrigerator or the furnace starts, some of the lights may dim. If a large enough change occurs, such as the start-up of a large industrial motor, lights can dim or brighten, not only for that customer but all over town.

Making a crossing in some rough water

Each of these Power Quality Indices provides an insight into a particular topic related to the Power Quality of a Power Distribution Grid. For each of them, particular measurements have to be done, in accordance with the international standardization - IEC 61000-4-30. Imagine the above-mentioned river. The turbulence of the river can be caused by a large number of factors. To properly identify the cause of the turbulence and the actions needed to be taken in order to minimize it, one has to accurately investigate the river on every level.

But this in the next episode. Stay tuned and follow us for more energy stuff.

Power Quality Indices content source.