In recent years, the application of renewable energy resources (RES) with DC output has increased, and RES integration as DC islanded microgrids (DC ImGs) has attracted the attention of many researchers. However, DC ImGs face many challenges, and voltage stability is extremely critical for efficient power distribution. This challenge becomes more prominent when exogenous disturbances, as well as time-delay, exist in the system mainly because of the communication network. In this study, we develop a mathematical model of the time-delay DC ImG. To compensate for the effect of the time-delay, three control strategies are introduced-stabilizing, robust, and robust-predictor. The controller's stability is guaranteed based on the Lyapunov-Krasovskii theorem, whereas for the exogenous disturbance rejection, the L 2-norm of the system is reduced. Furthermore, to obtain the proposed controllers' gains, linear-matrixinequality constraints are formulated. The performances of the controllers are investigated through numerous simulations, and a detailed analysis is presented.

The integration of renewable energy resources to DC microgrid has captured the attention of the researchers in recent years. One of the active field of application of DC distribution is the islanded DC microgrid (DC ImG). The DC ImG present numerous challenges to researchers. Among many challenges, the regulation of voltage and stability of the system is indispensable to efficient operation. The voltage stability problem becomes more prominent when the system is exposed to disturbances and possess uncertainties in parameters. However, challenges can be overcome by skilful design of a robust controller for the system. Therefore, in this paper, an output-feedback based centralized robust control scheme is proposed. The proposed controller is designed to maintain good control performance in the presence of parametric uncertainties and exogenous disturbances. The uncertainties of the DC microgrid is modelled as a linear time-varying state-space system. The upper and the lower bounds of the time-varying parameters are determined by a Lebesque-measurable matrix. To attenuate the exogenous disturbances of the system [Formula: see text] based output-feedback controller is designed. The system stability is assured by the Lyapunov function candidate. The output-feedback controller needs only the voltage measurement; therefore, it requires less communication bandwidth as compared to the state-feedback. To obtain the controller parameters linear matrix inequality constraints are formulated and solved. The performance of the proposed controller is verified via simulations and compared with the existing schemes.

The Internet has evolved in ways that we could never have imagined. In the beginning, advancements occurred slowly. Today, innovation and communication are happening at a remarkable rate. Now days, Internet has become the most important aspect of our life. Starting from desktop late 90s when one use to go to the device to resolve the problem to the era of smart devices early 20s when everybody carry the devices in its pocket to the new emerging era of internet of everything where we are going to connect each and every non connected device present on the planet.Even though cloud computing has played an efficient role in the computation and processing of these data, however, challenges, such as the security and privacy issues still cannot be resolved by using cloud computing. To overcome these limitations, the term fog computing has emerged to provide computing resources at the edge of the network. Fog computing is the extended version of cloud computing having the same data storage and computation capabilities but is fundamentally distributed in nature by providing services at the edge of the network.In this paper, I have given the brief description about the Fog computing, elaborate its complicated architecture, highlighted few feasible application and mentioned about the current security and privacy issues with the recommended security measures which we are going to face while deploying internet of things in to live environment.

With the evolution of the More Electric Aircraft (MEA) concept, high pulse converters have gained the attention of researchers due to their higher power quality. Among the high pulse converters, 18-pulse autotransformer rectifier unit (ATRU) offers better power quality level with small size, weight and medium complexity. The conventional topologies of autotransformers that require the use of extra elements such as Inter Phase Transformers (IPT) or Zero Sequence Blocking Transformers (ZSBT), adding to the complexity, weight and size of the overall system, are not considered in the analysis. For 18-pulse rectification, only those topologies of autotransformers which have the intrinsic current harmonic cancellation capabilities are presented here for comparison. These topologies offer current harmonic levels within limits specified by IEEE 519 with reduced weight and size as compared to the conventional multi-pulse converters. A comparison of different differential delta/fork configured 18-pulse autotransformer rectifier units is presented so as to come up with the best among available topologies with respect to weight, size and power quality. Experimental prototypes of each topology were designed and their results are displayed along with the simulation results for comparison.

This paper presents an easy and accurate procedure of the modeling of a commercially available Photovoltaic Panel by using Solar Module (Physical Model) Simulator embedded in a very powerful Simulation software known as PSIM. Methods of Photovoltaic Panel modeling including mathematical modeling and software based modeling are also discussed in this paper. Apart from modeling types, I-V (Current-Voltage) and P-V (Power-Voltage) Characteristics and some other useful results obtained from PSIM Simulation are further evaluated and compared with the laboratory test results. Limitations of PSIM Solar Module (Physical Model) are also discussed in this paper.

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Switching models possess discontinuous and nonlinear behavior, rendering difficulties in simulations in terms of time consumption and computational complexity, leading to mathematical instability and an increase in its vulnerability to errors. This issue can be countered by averaging detailed models over the entire switching period. An attempt is made for deriving improved dynamic average models of three phase (six-pulse) and nine phase (18-pulse) diode rectifiers by approximating load current through first order Taylor series. Small signal AC/DC impedances transfer functions of the average models are obtained using a small signal current injection technique in Simulink, while transfer functions are obtained through identification of the frequency response into the second order system. For the switch models in Simulink and the experimental setup, a small signal line to line shunt current injection technique is used and the obtained frequency response is then identified into second order systems. Sufficient matching among these results proves the validity of the modelling procedure. Exact impedances of the integral parts, in interconnected AC/DC/AC systems, are required for determining the stability through input-output impedances.

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