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Power Converters and Control of Renewable Energy Systems
Frede Blaabjerg,Remus Teodorescu,Zhe Chen,Marco Liserre 전력전자학회 2004 ICPE(ISPE)논문집 Vol.- No.-
The global electrical energy consumption is steadily rising and therefore a continous demand to increase the power generation capacity. A significant percentage of the required capacity increase can be based on renewable energy sources. Wind turbine technology, as the most cost effective renewable energy conversion system, will play an important part in our future energy supply. But other sources like microturbines, photovoltaics and fuel cell systems may also be serious contributors to the power supply. Characteristically, power electronics will be an efficient and important interface to the grid for the renewables and this paper will first briefly discuss three different alternative/renewable energy sources. Next, various configurations of small and medium power conversion topologies are presented including their control (mainly for PV-systems). Finally wind turbine configuration and their control are described.
Lorand Bede,Ghanshyamsinh Gohil,Tamas Kerekes,Remus Teodorescu 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6
A typical application for parallel connected converters is in multi megawatt wind turbine systems. Manipulating the interleaving angle between the Pulse Width Modulated (PWM) carrier waves of each converter can result in reduced grid and DC link current ripple, thus the passive components from the DC link and grid filter can be minimized. In previous studies the optimization of the interleaving angle for either the grid current Total Harmonic Distortion (THD) or the DC link current ripple has been made. In this study a compromise is made in order to maintain a THD of the grid current in a level that complies with the standards, while in the DC link the current ripple is reduced. The dependency of the grid current THD and the DC link current ripple on the interleaving angle were determined by simulations. The results were also validated on a hardware setup.
Jaehong Kim,Guerrero, J M,Rodriguez, P,Teodorescu, R,Kwanghee Nam IEEE 2011 IEEE TRANSACTIONS ON POWER ELECTRONICS - Vol.26 No.3
<P>A decentralized power control method in a single-phase flexible ac microgrid is proposed in this paper. Droop control is widely considered to be a good choice for managing the power flows between microgrid converters in a decentralized manner. In this work, to enhance the power loop dynamics, droop control combined with a derivative controller is used in islanded mode. In grid-connected mode, to strictly control the power factor in the point of common coupling (PCC), a droop method combined with an integral controller is adopted. Small-signal analysis of the proposed control is shown both in islanded and grid-connected mode. The proposed control scheme does not need any mode switching action. Thus, it is relatively simple in control for full mode of operation. Smooth transitions between the operation modes and the effectiveness of the proposed control scheme are evaluated through simulation and experimental results.</P>
Juan C. Vasquez,Josep M. Guerrero,Mehdi Savaghebi,Remus Teodorescu 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5
Power electronics based microgrids consist of a number of voltage source inverters (VSIs) operating in parallel. In this paper, the modeling, control design, and stability analysis of three-phase VSIs are derived. The proposed voltage and current inner control loops and the mathematical models of the VSIs were based on the stationary reference frame. A hierarchical control for the paralleled VSI system was developed based on three levels. The primary control includes the droop method and the virtual impedance loops, in order to share active and reactive power. The secondary control restores the frequency and amplitude deviations produced by the primary control. And the tertiary control regulates the power flow between the grid and the microgrid. Also, a synchronization algorithm is presented in order to connect the microgrid to the grid. The evaluation of the hierarchical control is presented and discussed. Experimental results are provided to validate the performance and robustness of the VSIs functionality during Islanded and grid-connected operations, allowing a seamless transition between these modes through control hierarchies by regulating frequency and voltage, main-grid interactivity, and to manage power flows between the main grid and the VSIs.
Bogdan Cursaru,Anita-Laura Radu,François-Xavier Perrin,Andrei Sarbu,Mircea Teodorescu,Ana-Mihaela Gavrilă,Celina-Maria Damian,Teodor Sandu,Tanta-Verona Iordache,Anamaria Zaharia 한국고분자학회 2020 Macromolecular Research Vol.28 No.3
In this study, composite hydrogels based on crosslinked polyethylene glycol diacrylate (PEGDA) and natural zeolite, with potential applications for the controlled release of phytoextracts, were synthesized by radical polymerization and characterized herein for the first time. The influence of various synthesis parameters, such as the use of distilled water or rose hip extract as reaction medium, or the percentage of the zeolite in the composite hydrogel upon the morphology, swelling kinetics and the rheological properties was investigated. By conducting polymerization of PEGDA in the rose hip extract, the crosslinking reaction yield was almost 100%, because of the chain transfer reactions of the polyphenols from the rose hip extract. Rose hip release tests were used to evaluate the release profiles of the natural bioactive substances from phytoextracts. The results showed that the hydrogel loaded with 3% zeolite displayed the lowest burst release and the slowest release rates of the extract.