A study on optimal placement of voltage sag monitors

Voltage sag is one of the most concerned power quality problems in recent years. This paper addresses the problem with respect to the placement of voltage sag monitors in large transmission systems. The proposed approach gives the least number of sag monitors and their positions. With the optimal location of all the monitors, both balanced and unbalanced faults in both buses and transmission lines can be detected by at least one of the monitoring devices. Finally the effectiveness of the proposed approach is finally verified by the case study based on IEEE-30 standard test system.