Abstract
In this paper it is presented a methodology to assess the dynamic voltage stability of an electric power system using trajectory sensitivity analysis. Trajectory sensitivity analysis can provide valuable insights into the security of an electric power system. In this study it was simulated a significant disturbance in two test power network. The Automatic Voltage Regulator of the generating units, the Under Load Tap Changer and loads models were taken into account. The simulation results were obtained using EUROSTAG program and post-processing module developed using the Matlab software package. © 2011 INESC Coimbra.

Abstract
State estimator is vital for on-line power system monitoring, analysis and control. With the increasing use of synchronized phasor measurement units (PMU) in power grids, how to utilize phasor measurements to improve the precision of state estimator becomes imperative. In this paper, a state estimator including voltage phasors, injected current phasors and traditional measurements is proposed. 14 IEEE bus system and 30 IEEE bus system are used as test systems and the simulation results demonstrate that the presented state estimation algorithm combining traditional SCADA measurements with PMU (Phasor Measurement Unit) measurements for power system state estimation improves the precision greatly. © 2011 INESC Coimbra.

Abstract
Wind energy is the renewable energy source with a higher growing rate in the last decades and can be considered a hope in the future as a clean and sustainable energy. With the huge proliferation of wind farms, as an alternative to the traditional fossil power generation, the economic issues dictate the necessity of monitoring systems to optimize availability and profits. Tools to detect the onset of mechanical faults in wind turbines at a sufficiently early stage are very important for maintenance actions to be well planned, because these actions can reduce the outage time and can prevent bigger faults that may lead to machine stoppage.

Abstract
Trajectory sensitivity analysis can provide valuable insights into the security of an electric power system. There is a strong correlation relating the system stability and the corresponding trajectory sensitivity. In this paper it is analyzed the influence of load shedding in the voltage stability of an electric power system using trajectory sensitivity analysis. It is recognized that voltage instability and collapse have led to major system failures. The emergency load shedding is one of the most important methods to preserve the system stability. In this study different values of load shedding were used to avoid voltage collapse. The automatic voltage regulators of the generating units and the turbine speed governors were modelled. Different load models were used and the under load tap changers were also taken into account. The simulation results were obtained using EUROSTAG program and post-processing module developed using the Matlab software package.

Abstract
This work presents a case study of the use of information and communication technologies (ICT) as part of the promotion of cooperative learning supported by computer in exterior lighting design, with solar energy. The influence and importance of ICT in various aspects, among which is the field of education, is already a subject practically defined and accepted. In this context the cooperative learning, including ICT, gives rise to the research area called cooperative learning supported by computer (CSCL). This study indicates the effectiveness of Problem Based Learning (PBL) in educating engineering students to make students more responsible in the contents area as well as in generic competences. By using PBL students get the opportunity to work or simulate real problems, making the learning experience much more meaningful. This method can also be seen as a benefit for Electrical Engineering programme where educators strive for improved teaching and learning.

Abstract
In this paper it is applied a Rough Set approach that takes into account an incomplete information system to study the steady-state security of an electric power system. The Rough Set Theory has been conceived as a tool to conceptualize, organize and analyze various types of data, in particular, to deal with inexact, uncertain or vague knowledge. The knowledge acquisition process is a complex task, since the experts have difficulty to explain how to solve a specified problem. So, an incomplete set of relevant information may arise. The study presents a systematic approach to transform examples in a reduced set of rules. These rules can be used successfully to avoid security problems and provides a deeper insight into the influence of parameters on the steady-state system performance. ©2009 IEEE.