National Institute of Technology, Meghalaya

About: National Institute of Technology, Meghalaya is a education organization based out in Shillong, India. It is known for research contribution in the topics: Control theory & Electric power system. The organization has 503 authors who have published 1062 publications receiving 6818 citations. The organization is also known as: NIT Meghalaya & NITM.

A novel control technique for a single-phase grid-tied inverter to extract peak power from PV-Based home energy systems

Abstract: In this paper, a single-phase full-bridge grid-tied inverter is considered for home-based photovoltaic applications. The dc-dc converter is inevitable in boosting the voltage and tracking the maximum power from the photovoltaic source. As a result, the size and cost of the home-based photovoltaic grid-tied systems increases. A dc-dc converter is eliminated in this work, and the PV voltage is considered as the input voltage to a single-phase full-bridge inverter system. Also, to overcome the demerits of traditional peak power techniques, a fuzzy logic-based peak power controller is proposed. A fuzzy logic-based dc-link voltage controller is also proposed to overcome the conventional PI-based dc-link voltage controller's demerits. Primarily the theoretical concept is validated by using the MATLAB/SIMULINK tool for simulation analysis. The Spartan-6 FPGA control board is used to implement the controller program. A laboratory prototype is fabricated in the experimental laboratory to verify the theoretical and simulation analysis. Different case studies are comprehended in this work to present the robustness of the recommended control scheme.

Estimation of phasor under dynamic conditions using convolution

Abstract: The paper introduces a simple, fast and computationally efficient phasor estimation algorithm under dynamic conditions using convolution analysis. The performance of convolution based phasor estimator is effectively tested under different dynamic/noisy conditions as per IEEE C37.118.1-2011 standards. The results revealed that the proposed algorithm estimates the dynamic phasor accurately irrespective of distortion present in the sinusoidal signals. The proposed algorithm enhances the phasor estimation process to be more general and independent of phasor models of a signal. Furthermore, the proposed estimator inherently filters noise and harmonics, immune to decaying dc components, detects sharp changes in a signal during faults and effectively works under complex modulated conditions. The simplicity, robustness and generality of the proposed algorithm best suits for wide area measurement systems to measure the voltage and current phasors during disturbance in the power system networks.

Analysis and Control of Chaotic Oscillation in FOSMIB Power System Using AISMC Technique

Abstract: It is well known that the chaotic oscillation is unacceptable for the healthy operation of the power system, it may reduce the boundary limit of steady state stability. Chaos due to boundary crises may lead the system to very serious situations such as voltage instability, angle instability and voltage collapse. In this paper, fractional order calculus is presented to analyse the single machine infinite bus power system (SMIB) model to investigate the nonlinear dynamical behaviour with more precision and accuracy. A robust fractional order adaptive integral sliding mode control (FO-AISMC) technique is designed to suppress chaos. The FO-AISMC technique can also handle unknown uncertainty present in the power system. The observation of chaotic oscillation is investigated with the help of bifurcation theory and Lyapunov exponents. FO-AISMC control laws are designed to control the chaotic oscillations. Lyapunov stability theory is used to devise the required stability condition. Simulation is achieved in MATLAB environment and verifies the theoretical approach.

A Promising Proton Conducting Electrolyte BaZr 1-x Ho x O 3-δ (0.05 ≤ x ≤ 0.20) Ceramics for Intermediate Temperature Solid Oxide Fuel Cells

Abstract: In this study, the Ho-substituted BaZrO3 electrolyte ceramics (BaZr1-xHoxO3-δ, 0.05 ≤ x ≤ 0.20) were synthesized through a low-cost flash pyrolysis process followed by conventional sintering. The effects of Ho-substitution in BaZrO3 studied in terms of the structural phase relationship, microstructure and electrical conductivity to substantiate augmented total electrical conductivity for intermediate temperature solid oxide fuel cells (IT-SOFCs). The Rietveld refined X-ray diffraction (XRD) patterns revealed that pure phase with $$Pm\bar{3}m$$ space group symmetry of cubic crystal system as originated in all samples sintered at 1600 °C for 8 h. The Raman spectroscopic investigations also approved that Ho incorporation in BaZrO3 ceramics. Field Emission Scanning Microscopic (FESEM) study informed a mixture of fine and coarse grains in the fracture surface of Ho-substituted BaZrO3 sintered samples. The relative density and average grain size of samples were observed to decrease as per the addition of Ho-substitution in BaZrO3 ceramics. The electrical conductivity study was accomplished by Electrical Impedance Spectroscopy (EIS) under 3% humidified O2 atmosphere from 300 to 800 °C. Furthermore, the total electrical conductivity of BaZr0.8Ho0.2O3-δ ceramic was found to be 5.8 × 10−3 S-cm−1 at 600 °C under 3% humidified atmosphere, which may be a promising electrolyte for IT-SOFCs.

Semi-isotropic design of a Stewart platform through constrained optimization:

Abstract: The isotropic property at home configuration for a semi-regular Stewart platform manipulator with equal leg lengths has been found to be nonachievable by kinematic design optimization study. In this context, a new approach of design optimization has been formulated here for achieving semi-isotropicity through variable transformation that has rendered the constrained optimization over a finite workspace to infinite workspace in the transformed domain. The proposed minimization methodology of a positive definite function for all the angular and translational motion has exhibited strong convergence to zero for values of the design parameters that can be worked out as a closed-form solution only for the cases of linear translation. Finally, the variations of the condition number over the permissible range of all single-degree-of-freedom motions have been carried out. The absence of any other minima in the entire workspace has clearly established the home position as globally optimized.