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 & Computer science. The organization has 503 authors who have published 1062 publications receiving 6818 citations. The organization is also known as: NIT Meghalaya & NITM.

A Switched-Capacitor Self-Balanced High-Gain Multilevel Inverter Employing a Single DC Source

Abstract: Multilevel inverters (MLIs) with self-balanced switched-capacitors (SC) have received wide recognition for increasing power capacity and power quality of the renewable energy and high-frequency power distribution systems. This brief presents a new SC MLI structure using a reduced number of switches and a single dc source. By suitable charging-discharging patterns, the SCs are self-balanced and high voltage boosting is achieved. Comparative analysis with state-of-art MLIs in terms of the number of components, standing voltage, boosting factor, and cost factor demonstrate the merit of presented topology. Further, experimental results confirm the workability of the proposed MLI under linear, non-linear loading and dynamic test conditions using both the 50 Hz and 2.5 kHz modulation.

Solution to automatic generation control problem using firefly algorithm optimized IλDµ controller

Abstract: Present work focused on automatic generation control (AGC) of a three unequal area thermal systems considering reheat turbines and appropriate generation rate constraints (GRC). A fractional order (FO) controller named as IλDµ controller based on crone approximation is proposed for the first time as an appropriate technique to solve the multi-area AGC problem in power systems. A recently developed metaheuristic algorithm known as firefly algorithm (FA) is used for the simultaneous optimization of the gains and other parameters such as order of integrator (λ) and differentiator (μ) of IλDµ controller and governor speed regulation parameters (R). The dynamic responses corresponding to optimized IλDµ controller gains, λ, μ, and R are compared with that of classical integer order (IO) controllers such as I, PI and PID controllers. Simulation results show that the proposed IλDµ controller provides more improved dynamic responses and outperforms the IO based classical controllers. Further, sensitivity analysis confirms the robustness of the so optimized IλDµ controller to wide changes in system loading conditions and size and position of SLP. Proposed controller is also found to have performed well as compared to IO based controllers when SLP takes place simultaneously in any two areas or all the areas. Robustness of the proposed IλDµ controller is also tested against system parameter variations.

An Improved Adaptive Control Strategy in Grid-Tied PV System With Active Power Filter for Power Quality Enhancement

Abstract: This article investigates the power quality enhancement of a grid-tied photovoltaic (PV) distribution system by employing a fuzzy logic proportional–integrator–derivative multiple complex coefficient filter multiple second-order generalized integrator frequency-locked loop (FLPID-MCCF-MSOGI-FLL) hybrid control scheme based shunt active power filter. The MSOGI-FLL reference current generation strategy is implemented to mitigate the current harmonics by extracting the fundamental constituents (FCs) from the nonlinear load currents, whereas an MCCF is employed to separate the FC from the distorted grid voltages and eliminates the voltage harmonics during extremely polluted grid voltage condition. The main objective of using FLPID is to maintain the stable power between dc and ac sides by regulating the dc-link voltage constant under transient conditions. To track the maximum power from the PV panel under varying environmental condition, the particle swarm optimization based perturb and observe technique is used in this article. The comparative analysis is analyzed to check the effectiveness of the proposed hybrid control scheme with existing and adaptive control techniques in respect of power quality, better dc offset rejection, better FC and frequency extraction, and grid synchronization. The system with the proposed control scheme is simulated on MATLAB/Simulink and validated in a real-time field-programmable gate array platform under different test scenarios. In conclusion, the harmonic content of grid currents and voltages is found well within the IEEE-519 standard limits.

FlowTrApp: An SDN based architecture for DDoS attack detection and mitigation in data centers

Abstract: Distributed Denial of Service attack (DDoS) is one of the severe security problems in data centers. In present times, data center operators adopt several hardware based dedicated measures for detection and mitigation of such attacks. It is a challenging task always to detect and mitigate DDoS attacks completely. Software Defined Network (SDN) provides a central control over the network which helps in getting the global view of the network. In this paper, we propose an SDN framework for data centers named FlowTrApp which performs DDoS detection and mitigation using some bounds on two per flow based traffic parameters i.e., flow rate and flow duration of a flow. It attempts to detect attack traffic ranging from low rate to high rate and long lived to short lived attacks using an SDN engine consisting of sFlow based flow analytics engine sFlow-RT and an OpenFlow controller. The proposed framework of FlowTrApp has been implemented in mininet emulator which outperforms an OpenFlow based QoS approach for DoS attack mitigation.