In this thesis, a new proposed method for LOF detection has been further explored and its shortcomings corrected. The detection index has been calculated based on these new modifications. The modifications include a more robust delta estimation technique and a removal of a required algorithm condition. Two methods are used to estimate the rotor angle and both provide a similar estimation. The first method depends on the integration of the rotor speed over time, while the second method is based on equations presented in a published paper.Moreover, the algorithm was tested on both a 2-bus system and the IEEE 9-bus system (The simulation model was built using a Real Time Digital Simulator (RTDS)) to investigate the detection time, security and reliability of the proposed method.The algorithm was then tested under various operating conditions. The advantages and drawbacks of the proposed algorithm are discussed in the thesis. iv DEDICATION I dedicate my dissertation work to my family and many friends. I must express my very profound gratitude to my parents and to my siblings for providing me with unfailing support and continuous encouragement throughout my years of study and through the process of researching and writing this thesis. This accomplishment would not have been possible without them. I also dedicate this dissertation to my many friends (Sara, Marym, Mariana and Mohammed) who have supported me throughout the process.