A novel methodology to locate originating points of voltage sags in electric power systems

Voltage sags cause more than 80% of the industrial customer complaints today, which signifies economic losses averaging $10,000.00 US per event. Electric utilities and the industry blame each other for the voltage sag generation. It is very difficult to identify precisely the originating point of voltage sag generation — with minimum equipment data provided — due to investment restrictions. In many cases the conflict has been solved in court. Considering the extra expenses involved, a methodology for the precise location of voltage-sag origin would be very welcome. The difficulty is due mainly to the wide variety of voltage sag causes and characteristics. In this paper, a problem is presented in detail, showing several actual cases and identifications of industry internal and external causes. Some typical waveforms are analyzed, from which an important insight can be obtained about the origin of voltage sags. A discussion is given about other proposed identification methodologies, their accuracy and possible improvements.