The development of wind generator dynamic model is of great interest nowadays. This manuscript presents the nonlinear characteristics of wind-generator system based on the squirrel cage rotor. The ...dynamic system becomes unstable due to uncertainty of wind speed circumstances. Therefore, a complete dynamic wind-generator modeling is carried out through the feedback control techniques, which plays a significant role in power system stability and control. The proposed control model consists of a 3-phase squirrel cage induction generator and implemented in the MATLAB software for the simulation in order to regulate the output parameters of the wind-turbine system. However, the proposed control design process has broadened prospectus of applications and developments. However, the simulation output response of proposed system yields a satisfactory performance.
This article presents a comprehensive review of reduced device count multilevel inverter (RDC MLI) topologies for PV systems. Multilevel inverters are widely used in medium-voltage and high-power ...applications such as wireless power transform applications, flexible AC transmission (FACT), active filters, AC motor drives, high-voltage DC transmission (HVDC), and renewable energy sources due to their high modularity and high-power quality output. Multilevel inverters have the ability to diminish the harmonics content in the output voltage by applying various modulation techniques. The literature in this field showed that the high-power quality and high modularity of the output demand an undeniable need for multilevel inverter topology. Research in this field has identified various multilevel inverter topologies, each possessing their own merits and demerits. The ubiquitous availability of multilevel inverter topologies illustrates the complexity of their accurate selection. To avoid such complexity, this review shows the state of the art of various reduced device count (RDC) multilevel inverter (MLI) topologies. Details of the various RDC MLIs, along with their comparisons, are provided in this paper. This review will be an important reference tool for future work on RDC MLI for photovoltaic (PV) systems.
Over the last couple of years, the use of DC-DC converters is being widely used in several applications. The need for a reliable and robust converter for application is very important because of the ...social impact that it can have on the losses in high-power electronics applications and output efficiency. This paper gives a comprehensive review of single-active-bridge (SAB) converters. The detail modelling and performance evaluation of SAB topology with PI controllers are also presented in this article. The performance of SAB topology is analyzed under transient and load variations. Due to the nonlinear behavior of SAB topology, the traditional PI controllers have not minimized transient disturbances. The major problem with the usage of conventional controllers and traditional configurations for the SAB converter are the ripples, which are generated in output voltage and current. These ripples severely affect the performance of the SAB converter. An effort has been made to analyze and contribute to the importance of a robust controller to mitigate the converter dynamics. This article also gives an in-depth dynamic analysis of SAB converters, which were controlled using PI controllers and failed to perform satisfactorily under non-linearities.
Multilevel inverters (MLIs) have recently attracted more attention in medium-voltage and high-power applications as they can provide an effective interface with photovoltaic (PV) systems. ...Conventional MLIs are used to generate higher voltage levels, which improve power quality and reduce the requirement for passive filters. However, recent research has focused on designing new MLI topologies using reduced switch counts and less voltage stress. This study, as such, proposes a new nine-level symmetric MLI for PV systems with a minimum number of switches. This decrease in the number of switches reduces the voltage stress across the switches and the number of driving circuits, which lowers the complexity of the control circuit and, as a result, lowers the cost and size of the system. This article compares the proposed MLI with other topologies based on the DC sources, switches count, gate driver circuits (Ngd), total standing voltage per unit (TSVPU), cost function (CF), and components count per level (CC/L). The proposed topology is integrated with the PV system. MATLAB software is used to evaluate the performance of MLI at step change in irradiance and under variable load conditions. The total harmonic distortion (THD) of the proposed topology is reduced with the implementation of phase disposition pulse width modulation (PD-PWM). In addition, PD-PWM is compared with phase opposition disposition pulse width modulation (POD-PWM) and alternative phase opposition disposition pulse width (APOD-PWM) modulation techniques. The simulation results reveal the improved performance of the proposed topology at variable irradiance and under varying load conditions. The comparison results reveal minimum (TSVPU), CC/L, CF, and switch count compared to existing topologies. Hence, the proposed topology of MLI is cost-effective and superior in all aspects compared to other topologies. In summary, it offers overall improved performance, and thus, it is feasible for the PV system.
A constant power supply is a basic need for each consumer due to the increase in sensitive equipment day by day. As per IEEE standards, a 10% reduction in voltage from the supply voltage is not ...acceptable and may cause the failure of equipment. Previously, different techniques have been used to alleviate the voltage sag, such as STATCOM, DSTATCOM, SVC, and shunt capacitors, but these devices are connected in parallel, which compensates for the low value of voltage sag, and they have high maintenance costs involved. Compensation for the low and high values of voltage sag is possible through a series-connected device such as a dynamic voltage restorer. In this paper, a matrix converter is presented for DVR to convert AC to AC voltage directly and free from batteries, capacitors, and multiple conversions as needed in a voltage source inverter, resulting in a reduced cost of DVR topology. The DVR is meaningless in the absence of a controller, so it is necessary to select a suitable controller for the satisfactory operation of the DVR under a variation of system parameters. In this paper, the performance of a linear PID controller is analyzed and compared with a nonlinear controller, such as a sliding-mode controller, under variation of power system parameters inorder to select a robust controller that performs satisfactorily for DVR. Earlier trial-and-error methods were used to obtain the parameters of PID gains, but they require a large time to obtain the parameters of the PID gains and there is a chance of inaccuracy. A genetic algorithm was used to obtain the gain parameters, but it has more convergence time and the particle swarm optimization technique has involves less reliability. In this research paper, the sliding surface coefficient parameters such as and Ki for the PI sliding surface of SMC and PID gains are taken through an ant colony algorithm to obtain the robustness of the controllers. The purpose of this paper is to introduce the best DVR topology with reduced cost. MATLAB simulation software was utilized to analyze the performance of the DVR with PID and SMC controllers under different fault conditions and also the THD% of proposed controllers was analyzed through FFT.
Dynamic Voltage Restorer—A comprehensive review Soomro, Abdul Hameed; Larik, Abdul Sattar; Mahar, Mukhtiar Ahmed ...
Energy reports,
November 2021, 2021-11-00, 2021-11-01, Letnik:
7
Journal Article
Recenzirano
Odprti dostop
Power quality problems such as voltage sag, voltage swell, voltage transients, voltage interruptions, and harmonics are becoming significant issues throughout the world. It has been seen that power ...quality problems resulted in the loss of more than 22 billion dollars in one year in industries of US and more than 500 consumers received a loss in the shape of damage or failure of equipments in 1991. A commonly occurring power quality problem in the electrical power distribution network is voltage sag which makes the sensitive loads of the network at risk. Static Synchronous Compensators, Distribution Series Capacitors and Power Factor Corrector, Static VAR Compensator, Uninterruptable Power Supply, and Solid-state Transfer Switches were used for stabilization but we are facing problems such as difficult maintenance, high cost of services and require large space. So valuable solution to mitigate the problem of voltage sag is the DVR. It is a series DVR. DVR is the series connected device which added the voltage to the load when needed. The most important component of a DVR is the Voltage Source Inverter; through this, we can provide the needful controllable voltage for compensation but it required energy storage device which results in high cost. The Matrix Converter has better performance as compared to other inverters due to direct conversion from AC to AC voltage and there is no need of energy storage unit which results in reduced cost and operational complexity. The control circuit is very essential for DVR; it retains a constant voltage and its magnitude at the load point. DVR is non-linear device due to presence of converter circuit, so for satisfactory performance of DVR, non-linear controller is essential. In this review paper, different topologies of DVR are discussed and performances of a DVR is analyzed under open loop system and also control strategy of PID controller through MATLAB simulation software.
Adopting
density functional theory (DFT) technique, the spintronic and opto-electronic characteristics of MnO
(
, Mn, MnO, MnO
, MnO
and MnO
) clusters intercalated bilayer AlN (BL/AlN) systems are ...investigated in this paper. In terms of electron transfer, charge transfer occurs from BL/AlN to the MnO
clusters. MnO
clusters intercalation induces magnetic behavior in the non-magnetic AlN system. The splitting of electronic bands occurs, thus producing spintronic trends in the electronic structure of BL/AlN system. Further, MnO
intercalation converts insulating BL/AlN to a half metal/semiconductor material during spin up/down bands depending upon the type of impurity cluster present in its lattice. For instance, Mn, MnO and MnO
intercalation in BL/AlN produces a half metallic BL/AlN system as surface states are available at the Fermi Energy (
) level for spin up and down band channels, accordingly. Whereas, MnO
and MnO
intercalation produces a conducting BL/AlN system having a 0.5 eV and 0.6 eV band gap during the spin down band channel, respectively. During spin up band channels these systems behave as semiconductors with band gaps of 1.4 eV and 1.2 eV, respectively. In terms of optical characteristics (
, absorption coefficient, reflectivity and energy loss spectrum (ELS)), it was found that MnO
intercalation improves the absorption spectrum in the low electron energy range and absorption peaks are observed in the 0-3 eV energy range, which are not present in the absorption spectrum of pure BL/AlN. The static reflectivity parameter of BL/AlN is increased after MnO
intercalation and the ELS parameter obtains significant peak intensities in the 0-2 eV energy range, whereas for pure BL/AlN, ELS contains negligible value in this energy range. Outcomes of this study indicate that, MnO
clusters intercalation in BL/AlN is a suitable technique to tailor its spintronic and opto-electronic trends. Thus, experimental investigation can be carried out on the systems discussed in this work, so as to fabricate practical layered AlN systems that are functional in the field of nano-technology.
Adopting ab initio density functional theory (DFT) technique, the spintronic and opto-electronic characteristics of MnOx (i.e., Mn, MnO, MnO2, MnO3 and MnO4) clusters intercalated bilayer AlN ...(BL/AlN) systems are investigated in this paper. In terms of electron transfer, charge transfer occurs from BL/AlN to the MnOx clusters. MnOx clusters intercalation induces magnetic behavior in the non-magnetic AlN system. The splitting of electronic bands occurs, thus producing spintronic trends in the electronic structure of BL/AlN system. Further, MnOx intercalation converts insulating BL/AlN to a half metal/semiconductor material during spin up/down bands depending upon the type of impurity cluster present in its lattice. For instance, Mn, MnO and MnO2 intercalation in BL/AlN produces a half metallic BL/AlN system as surface states are available at the Fermi Energy (EF) level for spin up and down band channels, accordingly. Whereas, MnO3 and MnO4 intercalation produces a conducting BL/AlN system having a 0.5 eV and 0.6 eV band gap during the spin down band channel, respectively. During spin up band channels these systems behave as semiconductors with band gaps of 1.4 eV and 1.2 eV, respectively. In terms of optical characteristics (i.e., absorption coefficient, reflectivity and energy loss spectrum (ELS)), it was found that MnOx intercalation improves the absorption spectrum in the low electron energy range and absorption peaks are observed in the 0–3 eV energy range, which are not present in the absorption spectrum of pure BL/AlN. The static reflectivity parameter of BL/AlN is increased after MnOx intercalation and the ELS parameter obtains significant peak intensities in the 0–2 eV energy range, whereas for pure BL/AlN, ELS contains negligible value in this energy range. Outcomes of this study indicate that, MnOx clusters intercalation in BL/AlN is a suitable technique to tailor its spintronic and opto-electronic trends. Thus, experimental investigation can be carried out on the systems discussed in this work, so as to fabricate practical layered AlN systems that are functional in the field of nano-technology.
Abstract
The enhanced power quality provided by multilevel inverters (MLIs) has made them more appropriate for medium- and high-power applications, including photovoltaic systems. Nevertheless, a ...prevalent limitation involves the necessity for numerous switches and increased voltage stress across these switches, consequently increasing the overall system cost. To address these challenges, a new 17-level asymmetrical MLI with fewer components and low voltage stress is proposed for the photovoltaic system. This innovative MLI configuration has four direct current (DC) sources and 10 switches. Based on the trinary sequence, the proposed topology uses photovoltaics with boost converters and fuzzy logic controllers as its DC sources. Mathematical equations are used to calculate crucial parameters for this proposed design, including total standing voltage per unit (TSVPU), cost function per level (CF/L), component count per level (CC/L) and voltage stress across the switches. The comparison is conducted by considering switches, DC sources, TSVPU, CF/L, gate driver circuits and CC/L with other existing MLI topologies. The analysis is carried out under various conditions, encompassing different levels of irradiance, variable loads and modulation indices. To reduce the total harmonic distortion of the suggested topology, the phase opposition disposition approach has been incorporated. The suggested framework is simulated in MATLAB®/Simulink®. The results indicate that the proposed topology achieves a well-distributed stress profile across the switches and has CC/L of 1.23, TSVPU of 5 and CF/L of 4.58 and 5.76 with weight coefficients of 0.5 and 1.5, respectively. These values are notably superior to those of existing MLI topologies. Simulation results demonstrate that the proposed topology maintains a consistent output at varying irradiance levels with FLCs and exhibits robust performance under variable loads and diverse modulation indices. Furthermore, the total harmonic distortion achieved with phase opposition disposition is 7.78%, outperforming alternative pulse width modulation techniques. In summary, it provides enhanced performance. Considering this, it is suitable for the photovoltaic system.
PDF
