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A supervision algorithm of ancillary services for distributed active front-end in a small industrial microgrid is presented. A comparison between distributed and centralized control of the active front-ends aimed to achieve optimal voltage regulation within the grid and minimal harmonic distortion both close to sensible loads and at PCC is performed.
In this paper a strategy for the compensation of harmonic currents in DC bus has been proposed. By means of a multilevel converter, low amplitude harmonic currents due to the interaction between primary converters operating in different conditions and connected to the same DC bus, are compensated. This strategy is suitable for the applications requiring a common DC bus such as Distributed Generations...
Design criteria for the AC link reactor of a Synchronous Active Front End (SAFE) system used as interface between a generic renewable energy source and the distribution grid is presented. After a brief description on the choice of the other system components, a variation range inside which the AC reactor value can be selected is proposed basing on an analytic approach. In particular, the lower limit...
Worldwide, request of renewable energy and power rating of wind farm is strongly increasing in parallel. This, makes more difficult the design of the power electronics converter that interfaces the grid to the renewable energy resource. Synchronous Active Front-End (SAFE) is considered one of the most efficient topology that successfully manages the hard trade-off between high power size and power...
In this paper, considerations on converter inductor design in PWM back-to-back converter based on Synchronous Active Front End (SAFE) are discussed. This is considered one of the most efficient converter topology that successfully manages the hard trade-off between high power size and power quality requirements at the Point of Common Coupling (PCC). In renewable energy, in wind farm, this trade-off...
In this paper a solution to current unbalance is proposed. A three-phase grid feeds a single-phase load that causes current unbalance. This is a typical situation for AC railway substations. By employing AC-Choppers it is possible to obtain a variable Steinmetz Circuit, and define a control law able to compensate a variable current unbalance. At this effect, a theoretical analysis of load unbalance...
This paper describes the advantages that can be obtained in ac/dc conversion, when an innovative four-quadrant converter, named synchronous active front-end (SAFE), is employed. The modular system, which increases the availability of the power delivering, can also be designed in order to obtain an improvement of the mission reliability. The reliability of single-AFE topology and the one of a SAFE...
With the request of renewable energy also the size of the wind turbines is growing. The converters used to connect them to the grid have to transfer a big amount of captured power. Since they handle high power, the switching devices work with a low switching frequency. This results in a high harmonic distortion of the injected currents and the need of big passive filters on ac side. In order to improve...
In this paper ancillary services performed by Distributed Generation (DG) sources connected to the grid are discussed. Wind energy is analyzed as case study of renewable DG source. Variable speed wind turbines are connected to the grid by power electronics converters, which are typically controlled in order to transfer to the grid the whole captured active power from the wind. Moreover a proper control...
In the present paper, an application of interleaved dc-dc converter in photovoltaic (PV) modular system has been presented. In the multi-string technology, several PV strings are interfaced with their own dc-dc converter to a common dc-ac inverter. Enlargements are easily achieved since a new string with dc-dc converter can be plugged into the existing platform. This paper proposes a simple method...
An innovative conversion system called synchronous active front-end (SAFE) is considered one of the most efficient solutions that successfully manages the well known trade-off between high power handling and good power quality. In wind energy applications switching converters are used to transfer the captured power to the grid. Their non-linear behavior must be considered, since the injected power...
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