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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...
On the base of the MMC principle, this work considers different topologies of sub module (or elementary converter) which make the High Voltage AC/DC converter more flexible and easy suitable respect to different voltage and current levels. A topological study is consolidated and extended on three different topologies proposed as elementary converter and their employment for the MMC structure is treated...
In this work the VSI structure is analyzed in Synchronous Active Front End configuration (SAFE). An analysis on power losses and thermal behaviors of the SAFE compared with its base version (AFE) is given. In these structures, due to the parallelization in current, the number of AC link reactors grows up with the number of interleaved converters. For this reason, at the end, an investigation on the...
In this paper, a converter control strategy able to provide ancillary services implemented for the Italian MV distribution Networks has been presented. A three stage system composed by several boost converters, a VSI Active Front End and a transformer has been considered as interface between distribution grid and DERs. The proposed control strategy operates jointly to the DMS. Simulations have been...
In this paper the use of an LLC resonant converter as Maximum Power Point Tracker (MPPT) in a photovoltaic application is presented. Two different implementations are considered: direct connection of the photovoltaic (PV) module to the grid and the string connection circuit. In Each solution the power converter efficiency is mainly limited by the step-up transformer. The impact of the transformer...
In this paper a converter for the compensation of a low amplitude harmonic currents for applications requiring a common DC bus such as renewable energy networks is presented. The considerations done can be easily extended to DC feeding line. The proposed multilevel converter is able to avoid problems to devices linked to a DC bus due to low frequency harmonic currents. It is also very useful in railway...
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...
In this paper, AC/DC converters for high voltage and high power applications are compared. Particularly Flying Capacitor Multicell and Modular Multilevel topologies are under consideration. The study is achieved in terms of power losses and total energy stored in the capacitors. A brief description of the topologies is given, and the main sizing criteria such as DC voltage, AC current and capacitor...
The effects of interharmonic distortion on Photo Voltaic (PV) inverters whose control is based on the use of PLL systems are analyzed. After some brief recalls on typical PV inverter connection schemes and control strategies, the design of the PLL and its sensitivity to the presence of interharmonic distortion is analyzed. Finally, a case-study on a very simple system is discussed with reference to...
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...
The effects of interharmonic distortion on static converters whose control is based on the use of PLL systems are analyzed. After some brief recalls on amplitude and phase angle modulation produced by interharmonic distortion and on basic PLL techniques, a sensitivity analysis aimed to show the performance of the presented PLL systems in presence of interharmonic voltages superimposed to the fundamental...
In this paper, a methodology for power losses analysis in Active Front End (AFE) converters based on VSI has been proposed. The interest in these converters topologies in AC/DC conversion, have become more popular in recent years due to its employment in renewable energy applications. Thus, it is interesting to analyze this converters in terms of their thermal behaviors in order to evaluate the system...
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