FPGA Implementation of a Passive Filter for Harmonic Reduction in Inverter Outputs in PV-Based Renewable Energy Systems
01 Jan 2018-pp 501-514
TL;DR: Simulation and experimental results prove the utility of the designed LC filter for PV applications and validate the effectiveness of the filter design with respect to total harmonic distortion reduction, improved output waveforms and reduced resonant peaking.
Abstract: Passive filters are considered as the most inexpensive solution to reduce harmonics. This paper focuses on the design and analysis of inverter output LC-type passive filter for harmonic reduction in PV-based renewable energy systems. The design procedure is based on resonant frequency characteristics, and Bode plots are presented to validate the effectiveness of the filter design. Simulation and experimental results are projected to validate the filter design with respect to total harmonic distortion reduction, improved output waveforms and reduced resonant peaking. A FPGA-based pulse-width-modulated inverter prototype is implemented using SPARTAN 3E-XCS250E processor. Experimental results prove the utility of the designed LC filter for PV applications.
References
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TL;DR: In this article, the authors focus on inverter technologies for connecting photovoltaic (PV) modules to a single-phase grid and categorize the inverters into four classifications: 1) the number of power processing stages in cascade; 2) the type of power decoupling between the PV module(s) and the single phase grid; 3) whether they utilizes a transformer (either line or high frequency) or not; and 4) the kind of grid-connected power stage.
Abstract: This review focuses on inverter technologies for connecting photovoltaic (PV) modules to a single-phase grid. The inverters are categorized into four classifications: 1) the number of power processing stages in cascade; 2) the type of power decoupling between the PV module(s) and the single-phase grid; 3) whether they utilizes a transformer (either line or high frequency) or not; and 4) the type of grid-connected power stage. Various inverter topologies are presented, compared, and evaluated against demands, lifetime, component ratings, and cost. Finally, some of the topologies are pointed out as the best candidates for either single PV module or multiple PV module applications.
3,530 citations
16 Jun 2003
TL;DR: In this article, the authors discuss two types of filters: band pass filters and damped filters, and show that in most distribution systems it is practical and economical to implement passive filter designs, provided the required safeguards are considered.
Abstract: New topologies for harmonic mitigation and active filters have come a long way, and these address the line-harmonic control at the source. These mitigate some of the disadvantages of passive filters, however, for nonlinear loads above 1 MW the passive filters are an economical choice. This paper discusses two types of filters: band pass filters and damped filters, which are commonly applied. The operation of these filters is described with respect to the design and system limitations. The operating constraints are then superimposed. The development of this approach shows that there are design limitations and large system changes or modifications can result in higher distortion or even damage to filters in extreme cases. The constraints and limitations that a designer faces in implementing an effective filter design with modern tools of harmonic analysis, measurements, and system analysis are discussed. The paper shows that in most distribution systems it is practical and economical to implement passive filter designs, provided the required safeguards are considered.
625 citations
TL;DR: In this article, a grid-connected photovoltaic (PV) power system with high voltage gain is proposed, and the steady-state model analysis and the control strategy of the system are presented.
Abstract: A grid-connected photovoltaic (PV) power system with high voltage gain is proposed, and the steady-state model analysis and the control strategy of the system are presented in this paper. For a typical PV array, the output voltage is relatively low, and a high voltage gain is obligatory to realize the grid-connected function. The proposed PV system employs a ZVT-interleaved boost converter with winding-coupled inductors and active-clamp circuits as the first power-processing stage, which can boost a low voltage of the PV array up to a high dc-bus voltage. Accordingly, an accurate steady-state model is obtained and verified by the simulation and experimental results, and a full-bridge inverter with bidirectional power flow is used as the second power-processing stage, which can stabilize the dc-bus voltage and shape the output current. Two compensation units are added to perform in the system control loops to achieve the low total harmonic distortion and fast dynamic response of the output current. Furthermore, a simple maximum-power-point-tracking method based on power balance is applied in the PV system to reduce the system complexity and cost with a high performance. At last, a 2-kW prototype has been built and tested to verify the theoretical analysis of the paper.
468 citations
TL;DR: This paper analyzes the stability problem of the grid-connected voltage-source inverter (VSI) with LC filters, which demonstrates that the possible grid-impedance variations have a significant influence on the system stability when conventional proportional-integrator (PI) controller is used for grid current control.
Abstract: This paper analyzes the stability problem of the grid-connected voltage-source inverter (VSI) with LC filters, which demonstrates that the possible grid-impedance variations have a significant influence on the system stability when conventional proportional-integrator (PI) controller is used for grid current control. As the grid inductive impedance increases, the low-frequency gain and bandwidth of the PI controller have to be decreased to keep the system stable, thus degrading the tracking performance and disturbance rejection capability. To deal with this stability problem, an H∞ controller with explicit robustness in terms of grid-impedance variations is proposed to incorporate the desired tracking performance and the stability margin. By properly selecting the weighting functions, the synthesized H∞ controller exhibits high gains at the vicinity of the line frequency, similar to the traditional proportional-resonant controller; meanwhile, it has enough high-frequency attenuation to keep the control loop stable. An inner inverter-output-current loop with high bandwidth is also designed to get better disturbance rejection capability. The selection of weighting functions, inner inverter-output-current loop design, and system disturbance rejection capability are discussed in detail in this paper. Both simulation and experimental results of the proposed H∞ controller as well as the conventional PI controller are given and compared, which validates the performance of the proposed control scheme.
388 citations
15 Jun 2003
TL;DR: In this article, the design considerations of the output filter for the grid-interconnected inverter were comprehensively discussed and different passive damping filter solutions were compared and the optimized design guidelines were also proposed.
Abstract: Traditionally, LC filter is used for an inverter power supply. A grid-interconnected inverter, however, has some unique requirements that an LC filter may not be sufficient. This paper comprehensively discusses the design considerations of the output filter for the grid-interconnected inverter. Different passive damping filter solutions are compared and the optimized design guidelines are also proposed. Simulation results are provided to validate the design.
360 citations