Abstract
This paper presents the Simulator of Intelligent Transportation Systems (SITS). The SITS is based on 2 microscopic simulation approach to reproduce real traffic conditions in an urban or non-urban network and considers, different types of vehicles, drivers and roads. A dynamical analysis of several traffic phenomena is then addressed.-The results of using classical system theory tools point out that it is possible to study traffic systems, taking advantage on the knowledge gathered with automatic control algorithms. In, this line of thought, it was also presented a new modelling formalism based on the embedding of statistics and Fourier transform.

Abstract
This paper discusses the problem of modelling and simulation of traffic systems, and presents the traffic simulator SITS (Simulator of Intelligent Transportation Systems). The SITS is based on a microscopic simulation approach considering different types of vehicles, drivers and roads. A dynamical analysis of several traffic phenomena is then addressed.

Abstract
In this paper it is studied and analyzed the impact of different security performance indices on a contingency screening and ranking algorithm. The proposed filtering technique consists of three modules, with different complexity levels. The contingencies are ranked in accordance with severity indices that allow assessing the influence of the overloads and voltage limit violations in the power network. The developed software package was applied to the IEEE 118 Test Power System. The simulation results that were produced using two different sets of security indices were compared, showing a satisfactory agreement The simulation was carried out considering a monotonous increase of the load level as well as a random one. For the different solutions the computing times were also obtained. Finally, some conclusions that provide a valuable contribution to the understanding of the Electric Power System security analysis are pointed out. © 2003 IEEE.

Abstract
In this paper it is proposed an efficient steady-state contingency classification using the Rough Set Theory. This approach allows the evaluation of the importance of particular attributes and the elimination of redundant attributes from the decision domain. Moreover, the construction of a minimal subset of independent attributes ensuring the same quality of classification as the original set. The elimination of redundant attributes can help in identification of strong non-redundant classification rules. The developed methodology produces a classification of the system operation in four possible states. The methodology developed by the authors was applied to a test power network and the results obtained were analysed. Finally, some conclusions that provide a valuable contribution to the understanding of the power system security analysis are pointed out.

Abstract
In this paper it is used a hybrid approach to study and analyse the tripping effect of one or more generators in the transient stability of a multimachine power system. This efficient and robust approach combines the advantages of the time domain integration schemes to compute the initial system trajectory with the equal area criterion. The transient stability assessment is obtained using stability indices. Consequently, the time domain simulation is only computed during a short integration period. This early termination procedure reduces drastically the computing time. The software package TRANsySTEM developed by the authors was applied to a multimachine test power network. The results obtained with this hybrid formulation were compared with the solutions produced by a time domain simulation program. Finally, some conclusions that provide a valuable contribution to the understanding of the generators tripping effect in the transient stability problem are pointed out.

Abstract
In this paper it is studied and analysed the influence of the selective load shedding in the dynamic voltage stability assessment of the BPA test power network. The outage of a 500 kV overhead transmission line was simulated. Different values of emergency 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 the commercial transient software package EUROSTAG, developed by Electricité de France and Tractebel Energy Engineering. Finally some conclusions that provide a better understanding of the voltage collapse phenomena are pointed out.