Abstract-Reliability assessment of distribution system, based on historical data and probabilistic methods, leads to an unreliable estimation of reliability indices since the data for the distribution components are usually inaccurate or unavailable. Fuzzy logic is an efficient method to deal with the uncertainty in reliability inputs. In this paper, the ENS index along with other commonly used indices in reliability assessment are evaluated for the distribution system using fuzzy logic. Accordingly, the influential variables on the failure rate and outage duration time of the distribution components, which are natural or human-made, are explained using proposed fuzzy membership functions. The reliability indices are calculated and compared for different cases of the system operations by simulation on the IEEE RBTS Bus 2. The results of simulation show how utilities can significantly improve the reliability of their distribution system by considering the risk of the influential variables.

The increasing environmental concerns during the 20th century have moved the research focus from conventional electricity sources to the renewable ones. In renewable power generation, wind energy has been noted as the most rapidly growing technology; it attracts interest as one of the most cost-effective ways to generate electricity from renewable resources. Moreover, using of power electronic devices to regulate and control of the generated power and transfuse to the grid is essential. In wind power systems, by using different control methods on the power electronic converter, synchronization of these resources to power grid is obtained. Studded wind turbine consists of a permanent magnet synchronous generator which is connected to the grid by a back to back (B2B) converter. In this paper, the main purposes are maximum point power tracking of wind turbine and transfusion to grid, control of reactive power by B2B converter and also fixing DC-link voltage in DC-link reference voltage. Proposed control method consists of vector control, combined tilt-integral-derivative compensator, and fuzzy controller. In order to verify the proposed method, a 1.5 MW wind turbine system is simulated in MATLAB/SIMULINK.

Abstract-Power electronic converters enable wind turbines, operating at variable speed, to generate electricity more efficiently. Among variable speed operating turbine generators, permanent magnetic synchronous generator (PMSG) has got more attentions due to low cost and maintenance requirements. In addition, the converter in a wind turbine with PMSG decouples the turbine from the power grid, which favors them for grid codes. In this paper, the performance of back-to-back (B2B) converter control of a wind turbine system with PMSG is investigated on a faulty grid. The switching strategy of the grid side converter is designed to improve voltage drop caused by the fault in the grid while maximum available active power of wind turbine system is injected to the grid and the DC link voltage in the converter is regulated. The methodology of the converter control is elaborated in details and its performance on a sample faulty grid is assessed through simulation.Index Terms--Back-to-back (B2B) converter, direct-in-line wind turbine, permanent magnetic synchronous generator (PMSG), voltage drop, wind turbine control.

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