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Numerical distance relays are used in modern power system to boost the performance and reduce the computational burden of relay. Quadrilateral zone of distance relay is more suitable and capable of boundary modification on protection scheme. In this paper, an adaptive distance relay is introduced to tackle the maloperation problems encountered in non-uniform structure of combined transmission system, in which the zone 1 of distance relay is modified. Two boundaries are modified with fifth degree of polynomial equation for quadrilateral zone characteristic. Appropriate objective functions are defined to minimize the increment in relay zone, maloperation rate, and boundary accuracy error. The multiobjective optimization problem is solved by using genetic algorithm. According to the extensive computational analysis results performed by MATLAB, the high accuracy of the proposed adaptive relay was achieved. Furthermore, the proposed method has the ability to encompass all faults and tackles the influence of various power system conditions by finding the optimized equation coefficients for the nonuniform structures.

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The utilization of renewable resources is growing, in part due to the environmental impacts caused by fossil fuels. The largest sources of renewable energy are wind and solar and many predict that these energy sources will be increasingly used for distributed generation. In this paper, the feasibility is examined of a grid-independent system applied for a remote area electrification in Binalood, Iran. Traditional power systems for remote or rural areas are based on fossil fuels. After addition of renewable energy resources, solar energy applications have become popular in remote energy systems. The recent study and research works show that adding other possible renewable energy resources such as wind, hydro and biomass could make a hybrid system more cost-effective and environmentally friendly. Hence, in the present study, an overview of applied hybrid renewable energy system (HRES) for worldwide villages with special attention on Iran has been proposed to help present and future works for better achievement in this field. Furthermore sensitivity analyses are performed to determine the impact on performance of several key parameters: wind speed and fuel costs. HOMER was used to evaluate the feasibility of various hybrid systems. The results of a comprehensive feasibility data analysis along with its economic evaluation indicate that the wind-diesel hybrid system with battery storage is most efficient energy system for supplying this remote area's electrical energy demands.