756 research outputs found
A Virtual Space Vectors based Model Predictive Control for Three-Level Converters
Three-phase three-level (3-L) voltage source converters (VSC), e.g., neutral-point clamped (NPC) converters, T-type converters, etc., have been deemed to be suitable for a wide range of medium- to high-power applications in microgrids (MGs) and bulk power systems. Compared to their two-level (2-L) counterparts, adopting 3-L VSCs in the MG applications not only reduces the voltage stress across the power semiconductor devices, which allows achieving higher voltage levels, but also improves the quality of the converter output waveforms, which further leads to considerably smaller output ac passive filters.
Various control strategies have been proposed and implemented for 3-L VSCs. Among all the existing control methods, finite-control-set model predictive control (FCS-MPC) has been extensively investigated and applied due to its simple and intuitive design, fast-dynamic response and robustness against parameter uncertainties. However, to implement an FCS-MPC on a 3-L VSC, a multi-objective cost function, which consists of a term dedicated specifically to control the dc-link capacitor voltages such that the neutral-point voltage (NP-V) oscillations are minimized, must be designed. Nevertheless, selecting proper weighting factors for the multiple control objectives is difficult and time consuming. Additionally, adding the dc-link capacitor voltages balancing term to the cost function distributes the controller effort among different control targets, which severely impacts the primary goal of the FCS-MPC. Furthermore, to control the dc-link capacitor voltages, additional sensing circuitries are usually necessary to measure the dc-link capacitor voltages and currents, which consequently increases the system cost, volume and wiring complexity as well as reduces overall reliability.
To address all the aforementioned challenges, in this dissertation research, a novel FCS-MPC method using virtual space vectors (VSVs), which do not affect the dc-link capacitor voltages of the 3-L VSCs, was proposed, implemented and validated. The proposed FCS-MPC strategy has the capability to achieve inherent balanced dc-link capacitor voltages. Additionally, the demonstrated control technique not only simplifies the controller design by allowing the use of a simplified cost function, but also improves the quality of the 3-L VSC output waveforms. Furthermore, the execution time of the proposed control algorithm was significantly reduced compared to that of the existing one. Lastly, the proposed FCS-MPC using the VSVs reduces the hardware cost and complexity as the additional dc-link capacitor voltages and current sensors are not required, which further enhances the overall system reliability
Model predictive control: a review of its applications in power electronics
Model-based predictive control (MPC) for power converters and drives is a control technique that has gained attention in the research community. The main reason for this is that although MPC presents high computational burden, it can easily handle multivariable case and system constraints and nonlinearities in a very intuitive way. Taking advantage of that, MPC has been successfully used for different applications such as an active front end (AFE), power converters connected to resistor inductor RL loads, uninterruptible power supplies, and high-performance drives for induction machines, among others. This article provides a review of the application of MPC in the power electronics area
Model Predictive Control for Power Converters and Drives: Advances and Trends
Model predictive control (MPC) is a very attractive solution for controlling power electronic converters. The aim of this paper is to present and discuss the latest developments in MPC for power converters and drives, describing the current state of this control strategy and analyzing the new trends and challenges it presents when applied to power electronic systems. The paper revisits the operating principle of MPC and identifies three key elements in the MPC strategies, namely the prediction model, the cost function, and the optimization algorithm. This paper summarizes the most recent research concerning these elements, providing details about the different solutions proposed by the academic and industrial communitiesMinisterio de Economia y Competitividad TEC2016-78430-RConsejeria de Innovacion, Ciencia y Empresa (Junta de Andalucia) P11-TIC-707
Model Predictive Control Technique of Multilevel Inverter for PV Applications
Renewable energy sources, such as solar, wind, hydro, and biofuels, continue to gain
popularity as alternatives to the conventional generation system. The main unit in the renewable
energy system is the power conditioning system (PCS). It is highly desirable to obtain higher
efficiency, lower component cost, and high reliability for the PCS to decrease the levelized cost of
energy. This suggests a need for new inverter configurations and controls optimization, which can
achieve the aforementioned needs. To achieve these goals, this dissertation presents a modified
multilevel inverter topology for grid-tied photovoltaic (PV) system to achieve a lower cost and
higher efficiency comparing with the existing system. In addition, this dissertation will also focus
on model predictive control (MPC) which controls the modified multilevel topology to regulate
the injected power to the grid. A major requirement for the PCS is harvesting the maximum power
from the PV. By incorporating MPC, the performance of the maximum power point tracking
(MPPT) algorithm to accurately extract the maximum power is improved for multilevel DC-DC
converter. Finally, this control technique is developed for the quasi-z-source inverter (qZSI) to
accurately control the DC link voltage, input current, and produce a high quality grid injected
current waveform compared with the conventional techniques.
This dissertation presents a modified symmetrical and asymmetrical multilevel DC-link
inverter (MLDCLI) topology with less power switches and gate drivers. In addition, the MPC
technique is used to drive the modified and grid connected MLDCLI. The performance of the
proposed topology with finite control set model predictive control (FCS-MPC) is verified by
simulation and experimentally. Moreover, this dissertation introduces predictive control to achieve
maximum power point for grid-tied PV system to quicken the response by predicting the error
before the switching signal is applied to the converter. Using the modified technique ensures the
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system operates at maximum power point which is more economical. Thus, the proposed MPPT
technique can extract more energy compared to the conventional MPPT techniques from the same
amount of installed solar panel.
In further detail, this dissertation proposes the FCS-MPC technique for the qZSI in PV
system. In order to further improve the performance of the system, FCS-MPC with one step
horizon prediction has been implemented and compared with the classical PI controller. The
presented work shows the proposed control techniques outperform the ones of the conventional
linear controllers for the same application. Finally, a new method of the parallel processing is
presented to reduce the time processing for the MPC
Model Predictive Controllers With Capacitor Voltage Balancing for a Single-Phase Five-Level SiC/Si Based ANPC Inverter
Employing both high bandwidth (HBW) controller and wide bandgap (WBG) devices in the structure of converters improve the system size, performance, and efficiency. In this paper, HBW model predictive controllers (MPCs) are proposed, with both fixed and unfixed switching frequencies, to control a single-phase five-level hybrid active neutral-point-clamped (ANPC) inverter. A hybrid modulation technique is considered in this paper, in which some of the switches are modulating with high frequency. Therefore, Silicon-Carbide (SiC) MOSFETs are employed in the converter structure to increase the switching frequency and consequently reduce the filter size and increase converter power density. To have the functionality of multilevel output voltage, some restrictions are defined in the adopted MPC with unfixed switching frequency. In the MPC with the constant switching frequency, predefined switching sequences are employed for all sectors. Moreover, to control the neutral point (NP) voltage, the applied times of both small voltage vectors are sets through a cost function. Finally, the simulation and experimental results prove the ability of both proposed methods to control the voltages of the load and NP.This work is licensed under a Creative Commons Attribution 4.0 License. For more information, see https://creativecommons.org/licenses/by/4.0/This work was supported by the APETT project, funded by Innovation Fund Denmark.fi=vertaisarvioitu|en=peerReviewed
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