Abstract
The operation and planning of Low Voltage (LV) and Medium Voltage (MV) distribution networks have been changing over the last decade. Due to the presence of Distributed Generation (DG) and microgeneration, an active role has been attributed to these networks in grid operation. For this accomplishment, different conceptual approaches were developed. In [1], a hierarchical control structure was defined, considering that DG units, onload tap changer transformers, static var compensators and loads can be controlled by a hierarchically higher entity, the Central Autonomous Management Unit (CAMC). The CAMC is also responsible for the management of specific LV networks, the MicroGrids (MG), which in turn have autonomy to manage their loads and microgeneration units through an entity called MicroGrid Central Controller (MGCC). A MV grid with these characteristics plus some storage devices would then be called a Multi-MicroGrid (MMG), being, among other functionalities, able to operate isolated from the upstream network. The recent appearance of a new type of load to the system, the Electric Vehicle (EV), expected to be largely integrated in the electricity grids in the upcoming years, has a great potential for adding controllability to the MMG. In this paper, an EV control droop (see [2]) will be introduced to improve the MMG performance when EVs operate as active elements. EV controllers are then able to receive setpoints from the CAMC and also actively update the droop settings in order to deal with different events that may occur on the MMG, for instance when moving from interconnected to islanded mode of operation. The performance of the MMG with controllable EV will be compared with a MMG without the participation of EV. Additionally, multiple philosophies for setting the droops will be tested, considering that EV may inject power into the grid as storage devices or just act as controllable loads. Simulation results were obtained exploiting a dynamic simulation platform developed using the EUROSTAG and MATLAB environments.

Abstract
The scope of this work is to find the best approach to control advanced inverters used to connect electric vehicles to the grid. Phase-locked Loop (PLL) is a grid voltage phase detection that makes use of an orthogonal voltage to lock the grid phase. This method is suitable for both single and three phase systems, although in single-phase, because they have less information, more advanced systems are required. The easiest way to obtain the orthogonal voltage system is using a transport delay block to introduce a phase shift of 90 degrees with respect to the fundamental frequency of the grid voltage. This method is known as Synchronous Reference Frame PLL (SRF-PLL). The use of inverse Park transformation is also possible. To lower the complexity and increasing the filtering of the output signals, methods using adaptive filters are a good alternative. For this approach, the use of a second order generalized integrator (SOGI) or Adaptive Notch filter combined with PLL, Enhanced PLL (EPLL) and Quadrature PLL (QPLL), leads to satisfactory results. © 2011 INESC Coimbra.

Abstract
This paper presents an original forecasting methodology for achieving the spatiotemporal future long-term expansion of small power photovoltaic (PV) systems in a region, taking into account the population density, ground usage and the type of small PV power application adopted. This methodology comprises three stages: a first stage based on a suitable PV technological forecasting method with a group of experts; a second stage consisting of an innovative and iterative process based on elimination of the possible numerical inconsistencies achieved in the first stage; a third stage with a new method for achieving PV power density maps, using a geographical information system (GIS), that provides significant quantitative GIS information and visual and geographically-disaggregated representation of future small power PV systems expansion. The proposed methodology is illustrated with a real example for the region of La Rioja, Spain. In this example, four different combinations of PV systems and geographical zones were considered, and they are referred to as four "PV technologies" in the paper. The forecasted period range was 20 years with steps of 5 years. The results offer very valuable information for electric utilities, PV systems sales and installation agents, investors and regional authorities responsible for energy plans.

Abstract
The uncertainties related to when and where electric vehicles will charge in the future requires the development of stochastic based approaches to identify the corresponding load scenarios. This paper describes a tool based on Monte Carlo techniques to be used for distribution grid planning, providing a characterization of possible grid operation conditions, regarding voltage profiles, branch loading, grid peak power and energy losses. A medium voltage network based on real data is used to illustrate the application of the developed methodology.

Abstract
This paper proposes technical solutions that can be implemented in variable speed permanent magnet synchronous generators driven wind turbine systems aiming to mitigate high voltage problems in low voltage MicroGrids by controlling the active power output. Due to the limited control capability of these systems, controlling the output power to prevent voltage rise will require the local accommodation of the generation surplus. For this purpose, additional control functionalities are developed to be integrated in the control systems of the power electronic based interfaces. Their performance is evaluated through numerical simulations performed in Matlab (R)/Simulink (R) environment and considering the detailed models of the power electronic converters. The results obtained demonstrate the effectiveness of the proposed control functionalities.

Abstract
In this paper it was studied the performance evaluation of Doubly-Fed Induction Generator (DFIG) in the analysis of dynamic voltage stability during Low Voltage Ride Through (LVRT) in electric power systems. Two models of wind turbines were analyzed. In one of the models the wind turbines are equipped with pitch control coupled with a Fixed Speed Induction Generator (FSIG) and a shunt capacitor bank. In the other model the wind turbines are equipped with DFIG, crowbar and chopper. To protect the rotor side converter from tripping due to overcurrents in the rotor circuit or overvoltage in the DC link during voltage dips a crowbar was installed in DFIG. Nowadays the most efficient plants use technologies that allow them to stay connected during a fault and to produce again normally after the disturbance The model used can take into account these new technologies. The automatic voltage regulators of the generating units, and the turbine speed governors were modelled in detail. Different load models were used and the under load tap changers were also taken into account. The simulation results were obtained using the EUROSTAG software package. Finally, some conclusions that provide a better understanding of the dynamic voltage stability of a system with FSIG and DFIG models during LVRT are pointed out. © VDE VERLAG GMBH.