Abstract
In this study, the authors analyse the social welfare impact of the integration of Portugal and Spain in the Iberian electricity market (MIBEL), taking into account the CO(2) price for emissions trading. They model the impact of emissions trading on the daily clearing prices and generation scheduling, and its effects on the benefits of integration as a whole. They compare the impact of market integration in Portugal and Spain and show that the welfare impact of the MIBEL is dependent on the CO(2) prices. From their analysis, they conclude high CO2 prices lead to a change in the merit order. Moreover, natural gas is the generation technology that most benefits from transmission constraints and from high CO(2) prices, as in the base case it is mainly used as a peak technology. The authors have also found that increases in the CO(2) prices do not lead to higher profits. Overall, the introduction of the MIBEL will increase social welfare by reducing generation costs and prices.

Abstract
In the scope of a recently launched European Research Project, a team of experts from public laboratories and TSO is in charge of defining the concepts and methodological approaches to design and analyse the technical and economic feasibility of future HVDC grids. This work aims at identifying, assessing and comparing several possible HVDC network topologies, with appropriate control and protection schemes, able to collect wind energy on large areas, transmit it at the best points to the AC grid and provide the necessary ancillary services for optimising the DC / AC interconnection in normal and disturbed conditions. The methodology adopted for the study and presented in this paper will focus on three main items: 1. identify and assess the economic drivers for the development of off-shore HVDC networks 2. identify the requirements for an optimal operation of the AC / DC interconnected power systems under normal and emergency conditions 3. conceptualise the coordinated control / command and protection plans for HVDC networks This paper gives a comprehensive view of the issues and tasks to be addressed during the run of the project.

Abstract
This paper presents a methodology for evaluating the impact resulting from the expected large scale integration of micro-generation (µG) in Low Voltage (LV) grids in Portugal. The proposed methodology allows the evaluation of the impacts in the entire LV and Medium Voltage (MV) distribution network by using typical load and generation profiles (24 hours) representing two well defined year periods (Summer and Winter). The simulations were performed in a time interval from 2008 to 2030, upon the definition of future scenarios related to the expected µG installed power in Portugal in the same period. Based on the obtained results, it was possible to quantify percentage gains related to the reduction of energy losses as a result of µ G integration in LV networks, avoided CO2 emissions and the possibility of achieving investment deferrals due to branches' congestion levels reduction or voltage profile improvements. ©2010 IEEE.

Abstract
This paper introduces several different indices in order to characterize the voltage stability of a power system. Voltage instability is a phenomenon which often contributes to the development of power system disturbances. Therefore, is very important to know how a power system is close to voltage collapse. The feasibility of the reported methods is shown by numerical studies in IEEE 57 bus test system. The simulation results are in close agreement.

Abstract
Terology is a concept introduced to synthesize all the actions related to the managing of the life cycle of facilities and equipment as an enlarged maintenance perspective. Nowadays, the concept tries to give some contribution to integrate the environment in this approach. The concept has been implemented in several fields, namely for wind mills in existing works. Now, it is expanded to the problem of marine wind farms taking into account the singularities of the marine environment. In fact, if the maintenance problems in wind farms are so diverse like the reading of on-condition data, their synchronization and, after, their transmission, in marine wind farms the problems are bigger, including the distance from GSM antenna to transmit and read data remotely. Additionally, and not less important, there is the distance between the marine wind farms and the staff responsible by its maintenance. In this case, the resources and time involved to develop maintenance interventions are much more expensive when compared to similar actions in land. Finally, nevertheless this kind of energy being green it also implies some environmental problems, related to the birds and fisheries.

Abstract