1,721,011 research outputs found
A Novel Phase-lock Loop with Feed-back Repetitive Controller for Robustness to Periodic Disturbance in Three-phase Systems
Full text link\ua9 2018 IEEE. While power networks evolve towards the new concept of smart grids, with the proliferation of power electronics embedded systems and distributed generation, the insurgence of system unbalance and voltage harmonic distortion, become more and more frequent. Also, often a noisy voltage sampling system can produce offsets in measurements. Such imperfections bring challenges to the phase identification using a traditional phase-lock loop (PLL), utilized in the control of all grid connected converters. However, since the imperfections lead to periodic harmonics in the corresponding dq-axis voltages, the repetitive controller (RC) can be useful for harmonic suppression. This paper presents a three-phase PLL using a feed-back RC. Specially, a novel running mean filter has been added to minimize the interaction between RC and the Proportional-Integral (PI) controller in the PLL. Simulation results show that the proposed PLL can track the phase of the three-phase voltage without being influenced by harmonic distortion
Reactive power control strategies for UNIFLEX-PM Converter
No full textThe paper presents various control strategies for an advanced multilevel-based power converter. A Fuzzy Logic Control, based on power balance constrains and Proportional Reactive Power control based on a more rigorous approach, have been proposed. Two different ways to assign reactive powers have been illustrated for both the control strategies and then compared in Matlab/Simulink environment accounting two active power sets. Finally, advantages and drawbacks of the proposed strategies have been highlighted. © 2016 IEEE
AC-DC Isolated Matrix Converter Charger: Topology and Modulation
No full textThis paper presents the modulation strategy for the 25 kW AC-DC isolated Matrix Charger three-phase rectifier (MCharger). The proposed topology allows current and voltage regulation for energy storage devices such as EVs batteries. Compared to a standard Dual-Active-Bridge topology, the Matrix converter allows to directly perform an AC-AC energy conversion thus eliminating the rectifying stage. A high frequency (HF) voltage waveform is generated to feed the isolation transformer, which is characterized by an almost negligible leakage inductance, allowing for the reduction of the transformer voltage drops. The rectification of the ac-waveform is achieved at the output stage, consisting of an H-bridge and an LC filter. The suggested topology powered with the proposed modulation is able to provide a wide output voltage range which can vary from 50 V to 500 V, providing up to a maximum power of 25 kW allowed for level I chargers. © 2020 IEEE
Real-time dynamics of plasmonic resonances in nanoparticles described by a boundary element method with generic dielectric function
No full textInvestigating nanoplasmonics in an explicit time-dependent perspective is a natural choice when light pulses are used and may also reveal aspects that are hidden in a frequency-based picture. In the past, we proposed a method time domain-boundary element method (TD-BEM) to simulate the time dependent polarization of nanoparticles based on a boundary element method that is particularly suitable to interface with a quantum atomistic description of nearby molecules. So far, however, metal dielectric functions in TD-BEM have been modeled through analytic expressions, such as those of Debye and Drude-Lorentz, which cannot account for multiple electronic resonances. Our approach allows us to include in the TD-BEM framework also the description of metals with complicate dielectric function profiles in the frequency domain. Particularly, among all metals, gold is a challenging case due to the presence of many transition frequencies. We applied our methods to different metals (gold, silver, and the less commonly investigated rhodium) and different shaped nanoparticles (spheres, ellipsoids, and cubes), the approach has been tested comparing TD-BEM and frequency domain BEM absorption spectra, and it has been used to investigate the time-dependent field acting locally close to nanoparticle vertices
A Novel Repetitive Controller Assisted Phase-Locked Loop with Self-Learning Disturbance Rejection Capability for Three-Phase Grids
No full textThe synchronization between the power grid and distributed power sources is a crucial issue in the concept of smart grids. For tracking the real-Time frequency and phase of three-phase grids, phase-locked loop (PLL) technology is commonly used. Many existing PLLs with enhanced disturbance/harmonic rejection capabilities, either fail to maintain fast response or are not adaptive to grid frequency variations or have high computational complexity. This article, therefore, proposes a low computational burden repetitive controller (RC) assisted PLL (RCA-PLL) that is not only effective on harmonic rejection but also has remarkable steady-state performance while maintaining fast dynamic. Moreover, the proposed PLL is adaptive to variable frequency conditions and can self-learn the harmonics to be canceled. The disturbance/harmonic rejection capabilities together with dynamic and steady-state performances of the RCA-PLL have been highlighted in this article. The proposed approach is also experimentally compared to the synchronous rotation frame PLL (SRF-PLL) and the steady-state linear Kalman filter PLL (SSLKF-PLL), considering the effect of harmonics from the grid-connected converters, unbalances, sensor scaling errors, dc offsets, grid frequency variations, and phase jumps. The computational burden of the RCA-PLL is also minimized, achieving an experimental execution time of only 12~mu ext{s}. © 2013 IEEE
Optimal control of matrix converters
No full textIn this paper a new control technique for matrix converter based on a Linear Quadratic Regulator (LQR) is proposed. Stabilization of matrix converter is often challenging due to the input filter resonance. The proposed method is compared with classical approaches for matrix converter control. It will be shown how the proposed approach can guarantee higher output current bandwidth providing also a good attenuation to grid disturbance. © 2019 EPE Association
Final design of the DTT Toroidal power supply circuit
Full text linkThe Divertor Tokamak Test (DTT) facility is in advanced design and construction phase at the ENEA laboratories in Frascati, Italy, to contribute to the study, the design and assessment of systems for the treatment of heat exhaust. The DTT Toroidal Field (TF) magnet system consists of 18 superconducting coils, fed in series by a single power supply (TFPS), which is a 24-pulses thyristor-based converter with an output DC current up to of 44 kA. In case of a quench in the superconductors, the magnetic energy stored in the coils is extracted by 3 Fast Discharge Units (FDUs) in series with 3 sectors of 6 TF coils. After the respective contracts were awarded, the TFPS and the FDUs are currently in the final design phase which is addressed in this paper. In particular, the analysis is focused on the most innovative aspects of the design, as the use of silicon carbide (SiC) varistors instead of discharge resistors and of a fully electronic and completely redundant high-current switch without any mechanical device
Three-port energy router for universal and flexible power management in future smart distribution grids
No full textNowadays the interest in active networks is significantly growing as a result of the larger diffusion of renewable energy sources and distributed generation systems connected to the grid. The possibility of installing in key points of these modern smart networks devices capable of intelligent energy routing and power flow control, is highly desirable in this scenario. Multilevel power converters and, in particular, Cascaded H-Bridge converters allow the required flexibility, availability and reliability to be considered as a building block for active nodes for the future electrical grid. This paper proposes a 3-port multilevel power converter capable of behaving as a network active node and demonstrates all its capabilities of energy routing and control under different operative conditions
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