Abstract
This paper is concerned with the behavior of a variable-speed wind energy conversion system, in order to assess the power quality injected in the electrical grid. Different topologies for the power-electronic converters are considered, namely two-level and multilevel converters. We use pulse width modulation by space vector modulation associated with sliding mode for controlling the converters, and we introduce power factor control at the output of the converters. We present the total harmonic distortion and the fast Fourier transform of the current injected in the electrical grid, considering each power-electronic converter. Finally, conclusions are duly drawn.

Abstract
This paper presents an overview of wind energy in Portugal and briefly describes the Portuguese Lightning Location System. Some aspects of lightning activity in Portugal are discussed. The method for risk assessment due to lightning flashes to earth is performed by the computer program LPS 2008 developed in Visual Basic by the authors. LIPS 2008 is based on well established standards and on the Rolling Sphere Method. LPS 2008 draws in 3D the most vulnerable points to lightning of a structure. A case study is presented to illustrate the protection measures resulting from this methodology, reducing damages due to lightning effects in power electronics and electrical machines to acceptable levels.

Abstract
This paper presents a new integrated model for the simulation of wind power generation systems. This model is not only more accurate but also computationally acceptable. It uses pulse width modulation by space vector modulation associated with sliding mode for controlling the converters. Power factor control at the output of the converters is considered in the model. We present a case study showing the harmonic behavior for the current injected in the electrical network, computed by the Fast Fourier Transform. Finally, we draw comparative conclusions between the performance of the matrix and Multi-level converters.

Abstract
In this paper, we propose a novel nonlinear approach to solve the short-term hydro scheduling problem under deregulation, considering head-dependency. The actual size of hydro systems, the continuous reservoir dynamics and constraints, the hydraulic coupling of cascaded hydro, systems, and the complexity associated with head-sensitive hydroelectric power generation still pose a real challenge to the modelers. These concerns are all accounted for in our approach. Results from a case study based on one of the main Portuguese cascaded hydro systems are presented, showing that the proposed nonlinear approach is proficient.

Abstract
This paper is on the unit commitment problem, considering not only the economic perspective, but also the environmental perspective. We propose a bi-objective approach to handle the problem with conflicting profit and emission objectives. Numerical results based on the standard IEEE 30-bus test system illustrate the proficiency of the proposed approach.

Abstract
This paper presents a brief characterization of wind power in Portugal, considering the installed power capacity, the capacity under construction, and the location of wind farms. It also describes the Portuguese Lightning Location System, and presents the results of the ccurrence of cloud-to-ground strikes both temporally and eographically distributed and the accumulative probability of the peak current. Based on these results, new ground flash density maps were drawn. Thus, this paper allows the characterization of discharges occurring in Portugal, helping to improve risk analysis and the protection systems adopted.