A power quality index based on equipment sensitivity, cost, and network vulnerability

This paper focuses on voltage sag phenomena and their impact on customer satisfaction. In order to derive a unique power quality of service index, information from both the supply network (according to standards in use) and the customer (defined in terms of load sensitivity and interruption cost) are merged. The well-known CBEMA power acceptability curve is revisited with definitions from the IEEE Standard 1159 superimposed. This depiction suggests a way to assign a cost or index of power quality events. Although individual cost assignments used in the calculation are subject to question, once the assignments are made, the calculation is consistent and gives a useful measure of quality of service. The method is illustrated factoring severity of the events based on the CBEMA curve and IEEE 1159 classified power quality events. The paper addresses the elusive issue of the cost of power quality disruption.