الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Directional protection is essential in transmission, sub-transmission and distribution, especially after the impact of high penetration of distributed generators and its integration in the networks that leads to bidirectional in power flow and fault current.
Traditional directional relays have used a voltage signal as a polarizing quantity which may be unreliable in cases of close-in faults and absence of potential transformer in distribution networks.
In this thesis, an investigation of novel directional relaying techniques which require only current measurement from current transformers and eliminate the use of the bulky and costly potential transformers associated with the type of protection in the traditional directional relays is presented.
Novel directional protection algorithms have been investigated, proposed and demonstrated. The new algorithms use only pre-fault and post-fault current signals for determining the fault direction excluding the need for voltage signals. The first method depends on the change in current phase angle before and after fault, the second method utilizes the post-fault current not only as a reference, but also as a polarizing quantity, whereas the third method is based on diagnosing of current waveform slope rise and Lissajous curves for detection of the fault and its direction respectively.
This thesis also presents a comparative performance study of the suggested techniques at different fault conditions.
Further, the investigated techniques are applied to actual data extracted from a digital protection relay, existing in the distribution network of Maadi, Cairo during a forward fault. Furthermore, these techniques are compared with experimental laboratory results for a reverse fault case.
The results of the investigated methods well agree with the actual measurements.