Power Quality

INTROUCTION

The aim of the power system has always been to supply electrical energy to customers. Earlier the consumers of electrical energy were mere acceptors. Interruptions and other voltage disturbances were part of the deal. But today electric power is viewed as a product with certain characteristics which can be measured, predicted, guaranteed, improved etc. Moreover it has become an integral part of our life. The term 'power quality' emerged as a result of this new emphasis placed on the customer utility relationship.

The fact that power quality has become an issue recently does not mean that it was not important in the past. Utilities all over the world have for decades worked on the improvement of what is now known as power quality. In the recent years, users of electric power have detected an increasing number of drawbacks caused by electric power quality variations. These variations already existed on the electrical system but only recently they are causing serious problems. This is because of the fact that end use equipments have become more sensitive to disturbances that arise both on the supplier as well as the utility side. End use equipments are more interconnected in networks and industrial processes, that the impact of a problem with any piece of equipment is much more severe. To improve power quality with adequate solutions, it is necessary to know what kinds of disturbances occurred. A power quality monitoring system that is able to automatically detect, characterize and classify disturbances on electrical lines is therefore required.

INCREASED INTEREST IN POWER QUALITY

Power quality is an increasingly important issue for all business. A recent study by IBM showed that power quality problems cost US business more than $15 billion a year. The increased interest in power quality has resulted in significant advances in monitoring equipments that can be used to characterize disturbances and power quality variations. The recent increased interest in power quality can be explained in a number of ways.
¢ Equipments have become more sensitive to voltage disturbances
The electronic and power electronic equipments have especially become much more sensitive to voltage disturbances than their counterparts 10 or 20years ago.
¢ Equipments cause voltage disturbances
Modern electronic and power electronic equipments are not only sensitive to voltage disturbances but also cause disturbances for other customers. E.g. Non-sinusoidal current drawn by rectifiers and inverters.
¢ Technical challenge taken up by utilities
Designing a system with a high reliability of supply at a limited cost is a technical challenge which appealed to many in the power industry and hopefully still does in the future.
¢ Power quality can be measured.
The availability of electronic equipments to measure and show wave forms has certainly contributed to the interest in power quality.