1,721,017 research outputs found
Comparative Analysis of Topologies to Integrate Photovoltaic Sources in the Feeder Stations of ac Railways
Full text linkThe increasing diffusion of renewable energy sources in the power systems is likely to extend in the near future to power supply of railways. This paper compares the technical and economic benefits of several configurations with power electronics converters for the integration of photovoltaic sources into the railway power supply systems. For each of these configurations, a design methodology is proposed for selecting the ratings of the railway power supply components. The requirements for the phase imbalance on the feeding transmission line are assumed in accordance with current regulatory standards and, wherever necessary, phase balancers are added. The design methodology is applied to the power supply of a high-speed railway and the configurations under study are numerically compared based on their technical feasibility and economic cost, using the generation capacity of the photovoltaic source as independent variable. The analysis demonstrates that with a progressive integration of PV sources into railway systems, the configurations with power converters supplying the overhead lines could become more beneficial than more classical solutions where the overhead line is supplied via a transformer
Ultracap-based new electrical drives for off-road vehicles and rovers
No full textGarching bei München (Germany
A comparison between line-start synchronous machines and induction machines in distributed generation
No full text
Harmonic compensation with active front-end converters based only on grid voltage measurements
No full textIn the recent years, there has been a considerable increment of diffused generators connected to distribution grids by means of power converters. These converters operate frequently below their rated power due to the fluctuation of the power generated by the renewable sources. In this scenario, power electronics interfaces could be also used as active harmonic compensators for other converters or distorting loads. Typically, these converters do not have information on other loads or on the level of grid current distortion. For this reason, this paper presents a new control algorithm for the grid harmonics compensation that relies only on the measurement of the voltage at the point of connection of the power converter. The reference of the compensating current is calculated from the harmonic content of the voltage in a reference frame synchronous with the grid voltage. Simulation results carried out on a sample distribution network with linear and nonlinear loads show that the proposed method does not require the knowledge of the harmonic current either of the grid or of the load and it is suitable when the distorting loads are unknown.</p
A single input dual buck-boost output reconfigurable converter for distributed generation
No full textThe diffusion of distributed electric generation sources is a growing phenomenon, encouraged by the changes in the electric energy market and the concerns about gas emission. Microgrids are composed by different types of generators, several loads and power converters necessary to interface all the microgrid components and the microgrid itself with the main AC grid. This paper presents a new flexible power converter capable of changing its topology by means of static switches so that it can provide different conversion functions using the same hardware. This proposal aims to reduce the number of components, enhancing compactness and simplicity, and resulting in lower equipment costs. The proposed converter is conceived for domestic microgrids, is connected to the AC grid and a renewable energy source (RES) and is configurable as a single-input dual-output (SIDO) converter, providing two different DC voltage levels. After showing all the possible configurations of this converter, the analysis focuses on SIDO, deriving its mathematical model and discussing a procedure to design its elements. The controllability of the SIDO is tested via numerical simulations showing good performance even during fast transient conditions.</p
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