الفهرس 
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Abstract
Traditional electrical distribution networks are radial in nature having only one source from a main grid and the power flow is unidirectional. In the last years, a new scenario has been appeared by connecting small power sources into distribution systems which is addressed as Distributed Generation (DG). DG provides an attractive alternative solution for producing energy. DG is an electrical power source connected directly to the distribution network and/or the customer site. The installation of DG gives great benefits for the distribution networks like voltage support, improved power quality, reduction in network losses, release of addition transmission and distribution capacity and improved reliability. The problem arises from the fact that traditional distribution systems are not prepared to operate with that new scenario. There are some challenges face DG insertion to the distribution network. These can be categorized as; technical constraints, cost constraints, and regulatory constraints. The protection issue is one of the main technical constraints.
This thesis investigates the impact of DG on the protection system on part of North Delta Electricity Distribution Company (NDEDC). The objective of this thesis is to find the maximum allowable DG penetration level that maintains the same protection system before DGs integration. NDEDC is a sample of a traditional network designed for unidirectional electricity feeding. Three real systems are studied in this thesis which represent all the protection devices in NDEDC network; cable system, over head lines (OHL) system and OHL with auto reclose (AR) system. A Matlab/Simulink model of the NDEDC network is developed and detailed simulations are performed to study the impact of DG integration to the system from the perspective of protection devices coordination. The NDEDC real data are implemented with all of the protective devices which are modelled with their practical settings.
The DG maximum allowable penetration levels for all systems are determined. Different scenarios for integrating the DG with the studied system have been implemented and discussed. Accordingly, several conclusions and recommendations are proposed for the current protection system of NDEDC.