AbstractsEngineering

newlineAppropriate long term planning to strengthen transmission newlinecapability is necessary to increase future reliability levels of the electric newlinetransmission system Economic and environmental constraints for newlinetransmission expansion have made power systems to operate closer to their newlinevoltage stability limit Operation beyond those limits can lead to equipment newlinefailure and blackouts This thesis concerns the stability and security of large newlineelectric power systems with a stress on static or longer term stability issues newlineThe main objective of this thesis is to monitor predict and assess the system newlineperformance for secure power system operation when the system needs newlinereactive power support or in case of emergency load shedding Voltage newlineinstability has become a major concern in many power systems and many newlineblackouts have been reported due to voltage instability The ability to newlinemaintain voltage stability depends on appropriate and accurate analysis of the newlinevarious operating conditions A fast method is required in order to perform newlinethis kind of assessment efficiently for operating conditions online A New newlineVoltage Stability Index NVSI is proposed which reflects both real and newlinereactive load variations at the receiving end of the transmission line for newlineproviding information at the current operating point It predicts the amount by newlinewhich system loads or power transfer can change before the occurrence of a newlinesecurity violation such as an overloaded transmission line or outages newline newline%%%appendic p155-124, reference p165-172.