الفهرس 
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Abstract
Transmission lines are critical part in electric power grids that are designed to transfer electric power from generation locations to distribution networks. However, their longitudes are exposed to many interruptions due to atmospheric conditions. Thereby, the reliability and stability of electric power grids are affected by various faults that are happened on transmission lines. Protective relay systems, based on measuring signals, are required to prevent the propagation of these faults. Developed protection systems are designed to be able to detect, classify, locate, isolate, and restore electric service as fast as possible.
This thesis is conducted in four parts. In the first part, the adaptive automated scheme is developed to improve the fault identification process in digital relay for transmission line. The proposed scheme has investigated an automated and sensitive fault identification process.
The second part presents a simple technique for fault identification for transmission lines using current measurements from single end measuring system. This scheme depends on the self- adaptive threshold value according to loading change, source parameter variation, and different network configurations. The proposed scheme is based on two criteria. The first criteria is dependent on the level of details coefficients while the second one is dependent on the deviation of details coefficients. The decision is obtained using an OR-logic of the two criteria.
The third part aims to investigate the fault identification scheme for digital relay in two terminal transmission lines in terms of the reactive power computation.