Project title: Take advantage of the Micro generation adding value to the Energy Produced & Quality of Service Network Electric
Description: Renewable energy generation is an area which demands for new studies due to extension of its application domain to low/medium power sources that have caused and keep on causing an evolution following two significant orientations, in next future: power of the renewable plants, wind, solar, and others has come down, appearing the valued concepts of micro generation and dispersed generation - being attributed economical worth to any suitable of generating power to small consumers; and so, interconnection with the grid is multi-point and at low voltage.
For small producers, analysis of the energy potential of a site é performed taking into consideration renewable alternative sources. So, within micro-generation and dispersed generation they appear new issues associated with specific problems of this domain:
- How to optimize simultaneous energy sources, keeping on MPPT operation for each one and considering their stochastic primary energies?
- How to contract a nominal power to be delivered to the grid?
- How to keep high standards for energy quality, in conditions of low voltage grid/very low short-circuit power and large dissemination of renewable sources in the network sector?
Grid connection of renewable sources based on power conversion has been studied in its technical consequences to electrical grid since a lot of years, namely harmonic content and active and reactive power flow. These issues associated to grid connection are the frame to formulate this project, now extending the domain to the new domain - low power /low voltage grid, simultaneous generation, dispersed generation, dissemination of the generating plants.
Host institution: Faculty of Engineering of Porto University, Portugal, 2010-2013, Project funded by the Foundation for Science and Technology (FCT)
Ref.ª: PTDC/EEA-EEL/109114/2008.
Project title: Modelization of an hipossíncrone cascade with two thyristor bridges and no dc coil
Description: The project was focused on the analysis and modelization of a slip energy recovery system (SERS), applied in the control of the speed of an asynchronous motor. The SERS, constituted by two thyristor full-bridges and no DC coil is used to increase the efficiency of the system, returning back to the motor the slip power recovered. The analysis on the influence of the value of the DC link inductance on the harmonics of the rotor current, the stator current are investigated and the oscillations of the electromagnetic torque are explained by considering the interaction between the stator and the rotor fundamental and harmonic currents. The system was modeled in MatLab/Simulink software and validated in an industrial real system in a cement plant CIMPOR – Souselas (Portugal). This project was contributed firstly for a better understanding of the system and secondly to solve the problems relating to its operation, with very high costs of production (unplanned stops of the manufacturing line). Several solutions to overcome the problems were implemented in order to take advantage of the full capabilities of the system.
Host institution: Collaboration between the Department of Electrical Engineering, University of Coimbra and Industry of Cements of Portugal, CIMPOR. Project funded by PRODEPII ,
Ref.ª: 3/94, Medida 5/ Ação 5.2.
Project title: A new high power efficient electronic converter for fuel cell applications
Description: The design and implementation of power generation systems based on fuel cells require careful selection of both the fuel cell model and the power converter. Therefore, a semi-empirical model of the PEM fuel cell is proposed in this project. In this context, a method to extract the parameters that characterizes the PEM fuel cell is secondary but also an important objective. This project also proposes a new efficient high power converter to improve the performance and optimize the hydrogen consumption. The converter follows a resonant approach that provides low component stresses, high frequency operation, soft-switching commutation, and operation under a wide range of input and output conditions. The control is divided into two parts, namely: i) the voltage controller, which is responsible for keeping constant the output voltage of the converter under loading variations and ii) the PEM controller, which is responsible for improving the performance by keeping the PEM fuel cell in its optimal operating point. The experimental setup composed by a DC-DC converter and a PEM fuel cell allows extending the analysis to new loading conditions such as electrical vehicles and renewable energy sources like solar energy. This project provides an accurate and useful tool for future research on these types of energy conversion systems.
Host institution: Institute of Systems and Robotics, University of Porto, Portugal, 2007-2011, Project funded by the Foundation for Science and Technology (FCT)
Ref.ª: SFRH/BD/47119/2008.
Project title: Fuel Cells test and integration for high power quality applications
Description: The main purpose of this project is to carry out a comprehensive study of the dynamic analysis of fuel cell based systems. Fuel cells are becoming one of the most important energy generating technologies. The special feature of the modern distributed generation technologies like fuel cells is the capability of such systems not only to generate electricity, but also heat in the form of steam or hot water with a minimal environmental impact. The critical role of dynamic modeling of fuel cell transient behavior can be justified by the possibility of providing high quality power and of improving the overall efficiency of the fuel cell system. A key issue is that fuel cell is a closed loop electrochemical and thermal system, which leads to the need for a dynamic model with high fidelity that incorporates both processes. The tasks of this project include the investigation of fuel cell transient behavior, load following capabilities and dynamic model definition. A strong focus is placed on the consideration of energy storage option allowing to change dynamic characteristics of the system. Fuel cell interconnection with the power grid is another subject of investigation. The penetration of small distributed generation units in the power generation market is becoming wider and the investigations on this territory are required looking at the interaction of fuel cell systems with the grid, namely in terms of load following capabilities, voltage control, reactive power and harmonic distortion. A particular emphasis will be placed in the design of an innovative fuel cell system to achieve a very high reliability supply, able to cope with the most demanding loads.
Host institution: Institute of Systems and Robotics, University of Coimbra, Portugal, 2004-2007, Project funded by the Foundation for Science and Technology (FCT)
Ref.ª: POCTI/ENR/59422/2004.