Abstract
European governments' targets for renewable energy by 2020 will lead to large offshore wind power integration in the existing Power System. High-Voltage Direct Current (HVDC) provides the most suitable technology to enable massive integration of offshore wind farms into AC onshore grids over long distances, with great control on transmitted power. More specifically, DC Grids (DCG) based on Voltage Source Converters (VSC) are being widely investigated to integrate multiple offshore wind farms dispersed over wide areas into AC onshore networks. For three and a half years, the « DC GRID » demo within the TWENTIES European project was focussed on a wide range of challenging issues related to the DC grid benefits for connecting offshore intermittent power: offshore DCGs economic assessment and likely layouts; DCG control and protection; ancillary services provided by such grids to the mainland AC network. This paper presents major achievements of the TWENTIES project in these domains. In addition, two major outcomes of the « DC GRID » demo are physical demonstrators. One of them is a low scale DCG mock-up, on which some of the above controls, as well as DC grid protection algorithms were successfully tested. Last, a highly innovative DC Circuit Breaker (DCCB) prototype was developed to overcome a strong technological barrier: this new equipment was successfully tested in presence of an independent expert to establish the qualification of this technology in the HV domain.

Abstract
During the last years, several plans for offshore grid development in Europe have been under discussion as a result of the need for the integration of large amounts of offshore wind power, providing additional transmission capacity and building adequate conditions for the single European electricity market. From the system operation viewpoint, technical constraints justify the need for adopting High Voltage Direct Current (HVDC) technology with Voltage Source Converters (VSC) for offshore grid development rather than conventional AC connections. Additionally, reliability and flexibility of operation is pushing for the development of the Multi-Terminal DC (MTDC) grid concept, by which a set of offshore wind farms is connected to a set of onshore AC nodes via a (possibly meshed) DC grid structure. This concept is in line with the envisioned plans for the development of the pan-European Transmission System. A broad range of aspects related to MTDC grids planning, operation, and technology was dealt within the TWENTIES European research project (2009-2013). In particular, this paper presents some results regarding the impact of MTDC systems on the AC systems they are connected to: specific focus is devoted to provision of advanced ancillary services (primary frequency controls, Fault Ride Through capability to AC faults, reactive power support), to the possible contribution of the MTDC grid in enhancing the operational security of AC systems and in restarting them after partial or complete blackouts. To emphasize the advanced functionalities that can be provided for overall system operation, this MTDC grid is referred to in the paper as "DC Grid" (DCG). Simulation results illustrate the potential benefits for the AC systems deriving from the described advanced control functionalities of DCGs. The work has been carried out within TWENTIES Working Package 5.

Abstract
3D worlds provide excellent platforms to achieve performance results when designed for the needs of students, helping them to improve acquisition and allowing greater interaction with contents in a unique way. © 2014 IEEE.

Abstract
This work aims at describing the added value of the skills acquired during a Master's degree in Building Services Engineering taught at the Instituto Superior de Engenharia de Coimbra in the departments of Electrical and Mechanical Engineering. It is based on the training final report of the dissertation, and it is concerned with the integration in the world of work, describing the framework of the various activities carried out during the internship. The curricular internship led to the acquisition of professional experience in the area of project within the framework of special technical installations, including lighting design in its various aspects. Several lighting design studies were developed both of interiors and exteriors and were extended to designs of bunkering stations, hospitals, post offices, hotels and homes in general. It also led to the acquisition of professional experience in the fields of electrical installations, telecommunications, fire safety in buildings and HVAC (Heating, Ventilation and Air Conditioning). The trainee had to assume responsibilities, applying theoretical knowledge to practical contexts developing decision-making skills and overcoming the proposed challenges. The opportunity the trainee had to follow the work of the technical teams was also an asset, as he observed on site the deployment of projects as they were being carried out He was also able to check if the work was evolving according to plans, contacted the architects, the building owners as well as the staff of companies in charge of other specialties. He experienced the difference between analysing and studying a two dimensional blueprint or even photos, and observing the actual design details on site, sometimes not so noticeable on paper or on the computer. This allowed him to assimilate important information, and be actively involved as part of the team, one of the reasons why the trainee opted for an internship of this kind that contributed to a better understanding of certain concepts in these areas of engineering.

Abstract
Virtual labs are more likely to offer a user friendly environment as well as greater flexibility, allowing students to carry out experiments and repeat them as often as necessary. Nevertheless, they do not discard the need for a conventional system as traditional labs are a valuable asset In this context, the student is the centre of the whole process, taking on the main role and is responsible for his/her own learning process, although there may be an extra support through in-class sessions in order to keep him/her in contact with the system, to offer guidance and motivation for the challenges ahead. One of the advantages of virtual experimentation is the opportunity of using a lab in situations which might be impossible otherwise, allowing students to take part in lab sessions; another one is related with its use to improve learning results. Virtual experimentation labs create flexible learning environments suitable for different types of learners, allowing the interactive and systematic development of competences in the various areas of learning and can be used to complement the conventional type of lectures. VEMA is a practical asynchronous software tool devised to meet the needs of students who can't be present in regular lab classes in the Electrical Engineering Department of ISEC (Instituto Superior de Engenharia de Coimbra).

Abstract
The quantity of educational digital content available for the hearing impaired community is very scarce. However, due to extraordinary progress of the new technologies, remarkable opportunities to bring a better quality of life to the public in general arose. Making these opportunities available to those who endure handicap and disabilities is a core concern in today's society and a must to promote equity and inclusion. The target community addressed by our work, the hearing impaired community, has its own language, known as Sign language. The work presented in this paper consists in the development of a game to make the process of learning sign language enjoyable and interactive. In order to do this, a game was created in which the player controls a character and interacts with various objects and non-player characters with the aim of collecting several gestures from the Portuguese Sign Language. These gestures can then be represented by the character. This allows the user to visualize and learn or train the various existing gestures. To raise the interactivity and to make the game more interesting and motivating, several checkpoints were placed along the level. This will provide the players a chance to test the knowledge they have acquired so far on the checkpoints by using Kinect. A High Scores system was also created as well as a history to ensure that the game is a continuous motivating process as well as a learning process. Copyright 2014 ACM.