Abstract

Abstract
This paper deals with a multi-objective control strategy for integration of distributed generation (DG) sources to the power grid. The proposed control technique can provide simultaneous compensation for active and reactive power, and harmonic current components of loads through integration of DG sources to the grid, which is the main contribution of this work over the other proposed methods. A dynamic model of the proposed DG model is first formulated in the stationary reference frame and then transformed into the synchronous orthogonal reference frame. The transformed variables are used in control of voltage source converter (VSC) as the heart of an interfacing system between DG sources and utility grid. By setting appropriate reference currents in the control loop of DG, the maximum available power of DG source will be injected to the grid with fast dynamic response, thereby achieving sinusoidal grid currents in phase with load voltages, while the required power of the load is more than the maximum injected power of DG to the grid. The effectiveness of the proposed control strategy is validated with injection of maximum available power from the DG source to the grid, increased power factor of the utility grid and reduced total harmonic distortion (THD) of grid current through simulation results under dynamic and steady-state operating conditions.

Abstract
Faculty of Sciences of University of Porto annually organizes the Open Days to Schools, which allow the contact of high school students with researchers from different scientific areas. By recognizing a high potential to modelling, which promotes the construction of students’ knowledge through models that recreate geological phenomena, participants contacted with some models that simulated the effect of earthquakes on soils and buildings. We tried to understand if the use of models in the dissemination of Geology helps students to build their scientific knowledge, concerning seismology contents. A seismology model evaluation scale was applied to 126 high school students from schools of northern Portugal, which participated in the activities at Open Days to Schools. The results shown that students consider that models help to clarify and to restructure their knowledge about geological phenomena, highlighting the importance of modeling in the promotion of a meaningful learning. © 2014 LNEG - Laboratório Nacional de Geologia e Energia IP.

Abstract
Several methodologies have been proposed in the last decades to improve the quality of Safety-Critical Embedded Systems (SCES) and, at the same time, keep costs and schedule compatible with project plans. In particular, approaches such as Product Line Engineering (PLE) and Model-Driven Engineering (MDE) offer an interesting solution to reduce development complexity and time to market due to their synergy and common goals. However, the current state of how MDE and PLE can be combined to enhance productivity in the domain of SCES is not clear yet. This paper presents a systematic literature review, with the purpose of obtaining the state of the art of the aproaches, methods and methodologies whose goal is the combination of PLE and MDE for the development of SCES, and to verify the existence of empirical studies that demonstrate the application of these techniques in this type of development. We drew the following conclusions from the review results: (1) The number of studies using PLE with MDE to build SCES is relatively small, but has increased gradually in recent years. (2) The approaches diverge about what is needed to build Model-driven Product Lines. (3) Most of the approaches do not consider to differentiate between hardware and software variabilities. (4) Most of the studies propose the use of UML and feature diagrams. (5) The studies present case studies implemented in different tools and most of them are free. (6) The approaches do not cover the entire development lifecycle.

Abstract
The forthcoming smart grids are comprised of integrated microgrids operating in grid-connected and isolated mode with local generation, storage and demand response (DR) programs. The proposed model is based on three successive complementary steps for power transaction in the market environment. The first step is characterized as a microgrid's internal market; the second concerns negotiations between distinct interconnected microgrids; and finally, the third refers to the actual electricity market. The proposed approach is modeled and tested using a MAS framework directed to the study of the smart grids environment, including the simulation of electricity markets. This is achieved through the integration of the proposed approach with the MASGriP (Multi-Agent Smart Grid Platform) system. © IFAC.

Abstract
This paper deals with a control concept for enhancing the stable operation of microgrid plan during the grid connected and islanding modes. The Lyapunov control theory is considered in this paper to analyze the dynamic behavior of distributed generation (DG) units during the power sharing with utility grid and loads. The compensation of instantaneous variations in the reference current components of DG units in ac-side and dc-voltage variations in dcside of the interfaced converters are considered properly in this control scheme, which is the main contribution of this work in comparison with the other potential control strategies. By utilization of the proposed control scheme, DG units can provide the continuous injection of active power from the dispersed energy sources to the local loads and/or main grid during the islanding and grid-connected modes. Furthermore, reactive power and harmonic current components of loads can be provided with a fast dynamic response in a stable operational region. Simulation results confirm the effectiveness of the proposed control strategy in the proposed microgrid plan during the dynamic and steady-state operating conditions.