This book presents the research works related to the development of new algorithms for line outage identification using voltage phasor of PMU. Three new voltage phasor-based algorithms are introduced. The proposed three models are 1) Direct comparison of phasor angle measurement (DCPAM) model 2) Comparison of bus current injection (CBCI) model 3) Comparison of bus power injection mismatch (CBPIM) model. The proposed algorithms also consider the constraints like PMU outage issue and measurement noises which reflect the novelty and reliability of the methodology. The performance of the proposed methodologies are checked on different IEEE test systems in terms of accuracy.