Browsing by Author "Rajkumar, K."

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A finite control set model predictive controller for single-phase transformerless T-type dynamic voltage restorer
(Springer Science and Business Media Deutschland GmbH, 2023) Rajkumar, K.; Grimm, F.; Parthiban, P.; Baghdadi, M.; Lokesh, N.
This paper presents a five-level T-type multilevel inverter (MLI) with a finite control set model predictive control (FCS-MPC) scheme for a single-phase transformerless dynamic voltage restorer (DVR). Typical two-level voltage source inverters are not suitable for high-power and medium-voltage applications due to high dv/dt, large size, and high cost of the filter, as well as high voltage stress on all switches. To overcome these issues, a reduced switch count T-type MLI-based transformerless DVR is proposed. The literature does not yet describe an FCS-MPC control scheme for transformerless T-type DVR. The FCS-MPC controller predicts the future of the trajectory of the controlled variables based on a prediction model. The optimal state is then selected using a cost function that is formed by combining predicted and reference variables. The proposed control technique minimizes the total harmonic distortion to a very low value compared to a linear PI controller. In addition, this control scheme is not dependent on a modulation scheme and linear control technique. The proposed system is validated by both simulation and experimental results. © 2023, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.
Chitosan composites reinforced with nanostructured waste fly ash
(Springer Japan, 2017) Patil, A.G.; Poornachandra, S.; Gumageri, R.; Rajkumar, K.; Anandhan, S.
This paper outlines the preparation and characterization of chitosan (CS) composites reinforced with mechano-chemically activated fly ash (MCA-FA). A series of composite films was prepared by solution casting method with varying filler content. Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) analyses showed good compatibility between the CS matrix and MCA-FA. The surface roughness and irregularity in shape of MCA-FA resulted in its efficient mechanical interlocking with the polymer matrix. This, in turn enhanced the mechanical properties of these composites. All the composite films exhibited a higher tensile strength and a lower percentage of elongation-at-break compared with the pure CS film. The highest tensile strength was observed for the composite films with 1 wt% of filler loading and the reduction in the tensile properties at higher filler loading was due to agglomeration of filler and polymer–filler interface debonding. The tensile strength data were analyzed using Nielsen and Pukanzsky models to understand the interface formation and polymer–filler interactions. Thermal properties showed a marginal improvement due to the incorporation of MCA-FA. Overall, this study indicates that MCA-FA could be used as value added filler in polymer matrix composites. © 2016, Springer Japan.
Control of transformerless T-type DVR using multiple delayed signal cancellation PLL under unbalanced and distorted grid condition
(Elsevier B.V., 2021) Rajkumar, K.; Parthiban, P.; Lokesh, N.
In the near future, the power system network may experience severe voltage distortions due to association of renewable energy sources (RES), and the large penetration of power electronic based loads into the microgrid. To protect sensitive loads from these distorted and unbalanced grid conditions, the commonly used dynamic voltage restorer (DVR) requires effective control algorithms. The effective control algorithm comprises a controller, and accurate estimation of grid phase angle/frequency, and magnitude, thereby the reference DVR voltage is accurately estimated. The synchronous reference frame based phased locked loop (SRF-PLL) is commonly used for phase angle estimation. However, during unbalanced, distorted, and dc-offset conditions, the performance of SRF-PLL is unsatisfactory. To improve its performance, it is cascaded with prefilters such as dual second order generalized integrator (DSOGI), cascaded delayed signal cancellation (CDSC), and multiple delayed signal cancellation (MDSC). Among these prefilters, MDSC has superior performance under all grid conditions with less delay time and memory requirement. In addition to an effective control algorithm, the DVR system requires high power density converters. The power density of the system is increased using transformerless T-type converter. In this paper, the effectiveness of MDSC-PLL for the transformerless T-type converter based DVR is evaluated in MATLAB/Simulink for various grid conditions such as voltage sag/swell, unbalance voltage sag/swell, harmonics, and dc-offset. © 2021 Karabuk University
Design, and Hardware Implementation of Semi-Z-Source Inverter based Transformer-less Dynamic Voltage Restorer
(Institute of Electrical and Electronics Engineers Inc., 2023) Remya, V.K.; Parthiban, P.; Nandakumar, A.; Ansal, V.; Rajkumar, K.
In this paper, design, and implementation of a semi-Z-source inverter based topology of Dynamic Voltage Restorer (DVR) is discussed. The topology utilizes the semi-Z-source buck inverter to synthesize the missing voltage for load compensation during power quality (PQ) events. The absence of filter components, elimination of shoot-through phenomenon, reduced size and cost of the SZS inverter are some of the attributes of the proposed DVR topology. The design and the hardware implementation of the laboratory prototype of the semi-Z-source inverter based DVR is elaborated in this paper. Â© 2023 IEEE.
Grid voltage detection method based on a novel adaptive notch filter for control of transformerless dynamic voltage restorer
(Institute of Electrical and Electronics Engineers Inc., 2020) Rajkumar, K.; Parthiban, P.
In the near future, the power system network may experience severe voltage distortions due to evolving concepts of microgrid, and the large penetration of power electronic based loads into a conventional grid. To protect sensitive loads from voltage disturbances under such severe grid conditions, the commonly used dynamic voltage restorer (DVR) requires control algorithms. Therefore, in this paper, widely used PI control strategy for transformerless single phase dynamic voltage restorer (DVR), based on a T-type multilevel inverter(MLI) is presented. In addition, the novel adaptive notch filter (NANF) is used for accurate extraction of DVR reference voltage for highly distorted grid conditions. Unlike conventional filters, NANF does not require phase-lock loop (PLL) or frequency-lock loop (FLL) for grid phase angle or frequency extraction. The performance of the system with the control algorithm is studied in MATLAB/Simulink to evaluate various power quality problems such as voltage sag, voltage swell, and harmonics. Â© 2020 IEEE.
Performance Investigation of Transformerless DVR Based on T-type Multilevel Inverter with Reduced Switch Count
(2019) Rajkumar, K.; Parthiban, P.
Voltage sag is typically the most severe power quality problem in power systems. Dynamic voltage restorers (DVR) are recognized to be a cost-effective solution for protection of sensitive loads from the power quality problems. Continuation of cost reduction, reliability and efficiency can be achieved by eliminating the injection transformer. This paper explains transformerless DVR based on a T-type multilevel inverter. The proposed DVR will not have an injection transformer which leads to less cost, less weight, and small size. The controller of the DVR is implemented by d-q transformation. The simulation results of dynamic voltage restorer are generated by MATLAB/SIMULINK software. � 2019 IEEE.
Performance Investigation of Transformerless DVR Based on T-type Multilevel Inverter with Reduced Switch Count
(Institute of Electrical and Electronics Engineers Inc., 2019) Rajkumar, K.; Parthiban, P.
Voltage sag is typically the most severe power quality problem in power systems. Dynamic voltage restorers (DVR) are recognized to be a cost-effective solution for protection of sensitive loads from the power quality problems. Continuation of cost reduction, reliability and efficiency can be achieved by eliminating the injection transformer. This paper explains transformerless DVR based on a T-type multilevel inverter. The proposed DVR will not have an injection transformer which leads to less cost, less weight, and small size. The controller of the DVR is implemented by d-q transformation. The simulation results of dynamic voltage restorer are generated by MATLAB/SIMULINK software. Â© 2019 IEEE.
Real-time implementation of transformerless dynamic voltage restorer based on T-type multilevel inverter with reduced switch count
(John Wiley and Sons Ltd vgorayska@wiley.com Southern Gate Chichester, West Sussex PO19 8SQ, 2020) Rajkumar, K.; Parthiban, P.; Lokesh, N.
This paper presents T-type multilevel inverter topology-based dynamic voltage restorer (DVR) with reduced switch count. In medium voltage and high-power applications, two-level voltage source inverters are insufficient because of more voltage stress on switches, large dv/dt, size, and cost of the filter. To overcome these problems, multilevel inverter-based DVR is suitable, which can be directly connected to the medium voltage distribution system without injection transformer. In addition, the control of the DVR is implemented by abc to dq controller. The voltage compensation capability of the proposed DVR is enhanced by employing the in-phase compensation technique with reduced carrier pulse width modulation scheme, and also the total harmonic distortion(THD) in the load voltage is reduced. The design and analysis of the proposed system are discussed, and its performance is validated in MATLAB/Simulink and in the OPAL-RT real time processor. © 2019 John Wiley & Sons Ltd