Voltage Sag Indices in Electrical Power Systems: Standards and Development
Voltage sag is defined as a short reduction in voltage magnitude for a duration of time. It is considered to be the most common power quality issue. This book presents various voltage sag indices proposed by electrical association organisations as well as ones suggested by researchers. Furthermore, mathematical descriptions of proposed voltage sag indices are derived. The indices are verified against various types of load, loading levels, and line X/R ratios. Mathematical analysis and verification against the IEEE four and thirteen node test feeders concludes in various versatile real time voltage sag indices known as the ?combined voltage index? and ?voltage sag proximity index?. In order to illustrate the real time applicability of the voltage sag indices they are used in conjunction with a mitigation technique, where they are proven to be efficient and discriminative. Furthermore, a methodology is mathematically developed and proposed for Interconnected System Voltage Sag Prediction. The proposed methodology is verified through successful application of the steps on IEEE four bus interconnected system.