Abstract
Penetration of renewable energy sources in isolated and weakly interconnected power systems can be increased in a secure and reliable way, if advanced control tools are available to the operators of these systems. In this paper the functions of MORE CARE are described. This is an advanced control software system aiming to optimize the operation of isolated and weakly interconnected systems by increasing the share of wind energy and other renewable forms, taking into account pumped hydro storage facilities and providing advanced on-line security functions, both in preventive and corrective mode. The main features of the control system comprise advanced software modules for load and wind power forecasting, unit commitment and economic dispatch of the conventional and renewable units and on-line security assessment capabilities integrated in a friendly Man-Machine environment. In this way, penetration of renewable energy sources in isolated systems can be increased in a secure and reliable way. Pilot installations of advanced control functions are foreseen on the islands of Crete, Ireland and Madeira.

Abstract
We describe an integrated methodology to compute long-term marginal prices in distribution networks. Long-term marginal prices are considered the most interesting and economically sound way of allocating network costs to users. Additionally, they inherently deal with the revenue-reconciliation problem, as they generally do not require other large supplementary tariff terms. The proposed methodology uses fuzzy sets to model uncertainties in load forecasts and considers several criteria to guide the identification of solutions. At the end, there is a final decision-making step to select the most adequate expansion plan according to the preferences of the decision-maker.

Abstract
This paper describes the general methodology that should be adopted to develop impact evaluation studies in distribution networks in case of connection of large amounts of dispersed generation (DG). It contains a description regarding the characterization of scenarios to be analyzed, problems to be addressed and tools to be used. Results from the analysis of a real network, where a large amount of dispersed generation (cogeneration) exists, are described. Technical issues to be tackled in the future and conclusions obtained from the studied examples are included.

Abstract
This paper analyses the security of an Electric Power System (EPS) using an efficient contingency filtering and ranking algorithm. The proposed technique is divided in three modules, with different complexity levels. The contingencies are ranked in accordance with severity indices that allow to accurately evaluate the impact of the overloads and voltage limit violations in the power network. The last module also includes indices that can detect voltage instability situations. The computer programs developed by the authors were applied to the IEEE 118 busbars 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
Voltage stability is concerned with the ability of a power system to maintain acceptable voltages at all busbars in the system under normal conditions, and after being subjected to a disturbance. A system enters a state of voltage instability when a disturbance causes a progressive and uncontrollable decline in voltage. In this paper it is studied and analysed the influence of the series capacitor compensation in the dynamic voltage stability assessment of an Electric Power System. It is used the BPA test power network considering different load models. A transmission line outage was simulated and different values of the series capacitor compensation were used to avoid voltage collapse. The automatic voltage regulators of the generating units and the turbine speed governors were modelled. The results were obtained using the software package EUROSTAG. Finally, some conclusions that provide a better understanding of the mechanism of the voltage collapse phenomenon that highlight the importance of the dynamic series compensation are pointed out.

Abstract
In this paper it is presented a three-step technique for on-line contingency screening, ranking and transient stability assessment based on a hybrid method. 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 computer programs developed by the authors were integrated in the software package TRANsySTEM. In order to validate the established mathematical models as well as the software package, the transient stability of the New England test power network was studied. The results obtained with the hybrid formulation were compared with the solutions produced by a time domain simulation program and show a very close agreement. Consequently, the proposed technique classifies correctly, without any dangerous diagnostic or false alarm, all the analysed situations. In addition, this approach provides the transient stability margins as well as the critical machines of the severe contingencies, therefore enabling further design of corrective security actions. Finally, some conclusions that provide a valuable contribution to the understanding of the transient stability assessment of a multimachine power system are pointed out.