Modal analysis of measured inter-area oscillations in the Mexican Interconnected System: The July 31, 2008 event

On July 31st 2008 at 8:46 a.m. local time a combination of system events involving operational changes and a weak transmission system resulted in wide-spread system oscillations in the Mexican Interconnected System. The events were captured by the CFE wide-area measurement system and used to investigate various features of the observed oscillations. Following the event of July 2008, studies were conducted to analyze system dynamic behavior as well as to compare real power grid performance to predicted system models. This paper discusses the practical experience with the analysis of the observed data. Procedures for assessment and quantification of system motion are reviewed and improvements in modeling tools and techniques to characterize system oscillations are investigated and tested. Field experience gained from the readjustment of power system stabilizers is also described. Finally, challenges of incorporating wide-area measurements into proper real-time warning systems are addressed.