The influence of the design and operation of protection and control on power quality

The power quality experienced by electricity supply customers is dependent on a number of parameters. These include the design of the power network, the operation of the network and the reliability of the generation, transmission and distribution plant and equipment. Power quality is extensively affected by power system faults and how efficiently these are dealt with by the protection and control equipment. Voltage dips are one of the most prevalent events on the utility power system which can adversely affect the power quality. The occurrence of voltage dips is costly, both to the customer and the national economy. In South Africa, the loss suffered by major industrial customers due to dips is more than R 1.2 billion per annum. This paper explores the influences of protection and control design and operation on power quality, focusing on voltage dips, and possible means to improve power quality through the adoption of different protection technologies, philosophies and application and setting practices. The paper covers some of the most recent work on the subject but also includes information from previous papers for completeness.