Wind parks and their impact on electrical power systems have become an important area for analysis over the last decade. Particularly, the influence of wind turbines on power quality of electrical power systems is today a subject of study for several electrical and wind turbine manufacturing companies, standards committees, and universities.In this paper, a new probabilistic model for analyzing electrical power fluctuations from wind parks with asynchronous generators is developed. The model is based on the aggregation of the linearized electrical and mechanical equations for wind turbines, and it can be used for power quality analysis. The proposed model is also used for assessing voltage and current fluctuations and flicker emission in the wind park.Index Terms-Asynchronous wind turbine, slow voltage fluctuation, synchronization of induction machines, wind energy, wind park.

This paper presents a method based on evolution strategies for designing large rural low-voltage (lv) distribution networks. Planning rural lv distribution networks involves radial configuration design, location of medium-voltage/low-voltage substations, and minimum cost. In this work, these goals are considered by taking into account different conductors, voltage drop and conductor capacity constraints, power losses in lines, and deterministic loads. The algorithms developed in this paper are based on evolution strategies (ES) and were implemented on large-scale rural lv distribution networks, but they could also be used in general network optimization.

This paper presents a method based on dynamic programming optimization to design distribution and industrial networks with unbalanced customers. Low-voltage and mediumvoltage network customers can be three-phase (i.e., industrial and commercial) and single-phase (e.g,. residential and rural areas). Moreover, American medium-voltage distribution networks have single-phase lines (rural areas) and three-phase lines (urban and primary feeders). Optimization of an unbalanced network implies optimal assignation of single-phase customers to each phase. This works considers different conductor types, tapering, power losses in lines, capacity and voltage drop constraints and deterministic loads, all employing single-phase and three-phase lines. The necessary modifications to apply it by single-wire earth return systems is presented.Index Terms-Distribution network planning, dynamic programming, industrial network, network design, single-phase customers, single-wire earth return system (SWER), three-phase.Eloy Díaz-Dorado received the Ph.D. degree in electrical engineering from the Universidade de Vigo, Vigo, Spain, in 1999.He is a Professor in the Departamento de Enxeñeria Eléctrica, Universidade de Vigo. His research involves estimation and planning of power systems.José Cidrás Pidre (M'92) received the Ph.D. degree in electrical engineering from the where he leads investigation projects into wind energy, photovoltaic energy, and planning of power systems.