One of the most complex disciplines in electrical engineering is power system protection which requires not only the proper understanding of the different components of a power system and their behaviours but also a good knowledge and analysis of the abnormal circumstances and failures that can occur in any element of a power system. Moreover, the rapid changing and development in relays principles as well as in their technologies are additional factors that oblige those people working in the field to expand and update continuously their knowledge. In this paper, we shed light in the evolution of protective relays since the onset of electrical energy to currently. We try also to foresee the future prospects and trends in this area.

Phasor Measurement Unit (PMU) is an instrument that has been developed for improving the protection first and then control and monitoring system in smart power grid. This advanced technology may be used to provide high-speed and coherent real-time information about the power system that is not obtainable in conventional supervisory control and data acquisition (SCADA) systems. This research work deals with the study of the conventional SCADA system that is based on RTU's and proposes how to integrate this technology PMU in SCADA system for improving its performance. To validate the present work, the performance of developed SCADA system is tested by power system Simulink model under different conditions. The obtained simulation results are satisfactory.

Almost all type of faults that occur in distribution network are self-clearing faults, so the protective relays must not break the power circuit and interrupting the power supply to the consumers. Therefore, a protective device such as auto-recloser is more suitable for this situation. An auto-recloser is a circuit breaker associated with a control circuit that may automatically re-close the circuit breaker after opening it due to the fault detection. Since more than 80% of the faults are self clearing in their nature hence, power outage time can be reduced if the reclosing function is automated and carefully planned. In this paper, a new frame work of smart auto-recloser has been implemented in PC associated with NI7851 Card using the Labview. To validate the present work, the performance of developed device has been tested by Power System Simulator under different conditions.

Electrical Faults in Power Systems: 10.4018/978-1-4666-9911-3.ch001: The identification and classification of electrical faults have a great importance in power system analysis. They help in the dimensioning and the adequate