The Importance of Good Power Quality

This paper explains the problems that are due to poor Power Quality in electrical systems and shows their possible financial consequences. Power Quality is characterized by parameters that express harmonic pollution, reactive power and load unbalance. The best possible solutions to these problems are reviewed and their control systems are elaborated on. Solutions present in the field are explained and field results are presented. It is shown that by using the right technology a variety of Power Quality problems can be solved rendering installations trouble free and more efficient, and can render them compliant with even the strictest requirements. INTRODUCTION Ideally, the best electrical supply would be a constant magnitude and frequency sinusoidal voltage waveform. However, because of the non-zero impedance of the supply system, of the large variety of loads that may be encountered and of other phenomena such as transients and outages, the reality is often different. The Power Quality of a system expresses to which degree a practical supply system resembles the ideal supply system.  If the Power Quality of the network is good, then any loads connected to it will run satisfactory and efficiently. Installation running costs and carbon footprint will be minimal.  If the Power Quality of the network is bad, then loads connected to it will fail or will have a reduced lifetime, and the efficiency of the electrical installation will reduce. Installation running costs and carbon footprint will be high and/or operation may not be possible at all. In order to characterize the Power Quality, different indices have been defined and will be reviewed later in this article. COST OF POOR POWER QUALITY Poor Power Quality can be described as any event related to the electrical network that ultimately results in a financial loss. Possible consequences of poor Power Quality include (Fig. 1):  Unexpected power supply failures (breakers tripping, fuses blowing).  Equipment failure or malfunctioning  Equipment overheating (transformers, motors, ...) leading to their lifetime reduction.  Damage to sensitive equipment (PC‟s, production line control systems, ...).  Electronic communication interferences.  Increase of system losses.  Need to oversize installations to cope with additional electrical stress with consequential increase of installation and running costs and associated higher carbon footprint.  Penalties imposed by utilities because the site pollutes the supply network too much.  Connection refusal of new sites because the site would pollute the supply network too much.  Impression of unsteadiness of visual sensation induced by a light stimulus whose luminance or spectral distribution fluctuates with time (flicker)  Health issues with and reduced efficiency of personnel, ...