الفهرس 
Types of reclosersOnly 14 pages are availabe for public view
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Abstract
With an increasing of industrial developments and consequently growing energy consumption, it is compulsory to generate enough amount of electric power to transmit on a continuous basis without interruptions. To achieve this, protection system associated with the power system must be able to identify and compensate any effects or fails in the system, which may lead to long term blackouts. Otherwise, more delays required to restore the system to its normal operation or damage to equipment, which is costly. The distribution system contains protection devices such over current relays (OCRs), reclosers, sectionalizers and circuit breakers (CBs). These protective devices are coordinated to interrupt the fault current from the source end towards the fault point. The function of protection devices is to detect the fault and trip the CB to isolate the faulty portion from the source to ensure the service continuity to the healthiest users. The OCR is one of the most important protective devices used in distribution networks as a protection tool against over current. By using auto-reclosing scheme, successful re-energization of the line can be achieved as transient faults take some time to be cleared. For permanent faults, the sectionalizer would be an effective device to isolate the faulty section only.
On the other hand, with the rapid increase in electrical energy demand, power utilities are looking for more power generation capacity in an optimal manner, economic and technical. Thus, developed technologies based on distributed generation (DG), renewable and nonrenewable. Renewable energy sources are becoming more acceptable as alternative energy generators such as wind, solar, and hydro, in addition to conventional gas turbines, conventional micro-turbines, and fuel cells as nonrenewable sources. Renewable DGs offer several compelling advantages, such as increasing the reliability of the distribution system, allowing grid expansion postponement, enhancing power quality, and optimizing efficiency for financial and trading purposes. However, the integration of DG sources may cause significant impacts on distribution networks, particularly the changes in magnitudes and directions of short circuit currents that may lead to false tripping or fail to trip over-current protection relays in the system. They pose problems for the traditional protection scheme; with non-directional OCR as the load flow in distribution systems are often not unidirectional.
The objective of the proposed work is to investigate the protection schemes for radial system with a goal of formulating a proposed scheme that uses a promising optimal optimization technique based on genetic algorithm (GA) for relays setting determination. The objective is minimizing the operating current of relays subjected to relay characteristic curves. Then, managing the DG units in relation to distribution protection relay coordination aiming to optimally allocate the DGs without changing the original relay protection scheme. Finally, finding out the optimal coordination of OCRs, reclosers and sectionalizers settings in the presence of DGs. The function of the proposed scheme is tested on the IEEE-33 distribution system and Egyptian Nediba distribution system with 47 buses.