Rishi Kant Sharma

Effects of Crystallinity of PP and Flexibility of SEBS-g-MA Copolymer on the Mechanical Properties of PP/SEBS-g-MA Blends

Mechanical properties of polypropylene and SEBS-g-MA copolymer blends up to volume fraction 0.5 of SEBS-g-MA are evaluated. Tensile properties and impact strength are described and correlated with theoretical models. Crystallinity on which strength properties depend decreases with increasing concentrations of SEBS-g-MA copolymer. Tensile modulus and strength decreased but tensile elongation and impact strength enhanced. Morphological studies show good dispersion of SEBS-g-MA in polypropylene with a weak level of interaction between the phases.

Effects of crystallinity of polypropylene (PP) on the mechanical properties of PP/styrene-ethylene-butylene-styrene-g-maleic anhydride (SEBS-g-MA)/teak wood flour (TWF) composites

Tensile and impact properties of PP/SEBS-g-MA/WF composites up to wood flour volume fraction 0.31 are evaluated. Tensile modulus and strength increased while elongation-at-break and Izod impact strength decreased with increase in volume fraction of the filler (Φf). The crystallinity of PP enhanced with Φf. The tensile properties were compared with predictive theories. SEM studies indicated formation of stress concentration points around WF particles with only limited extent of adhesion which led to large decrease in elongation-at-break and Izod impact strength of PP.

Effects of SEBS-g-MA copolymer on non-isothermal crystallization kinetics of polypropylene

AbstractThe non-isothermal crystallization kinetics of pure PP and PP/SEBS-g-MA blends up to volume fraction, Φd (0–0.50) was studied by differential scanning calorimetry at four different cooling rates. Crystallization parameters were analyzed by Ozawa and Liu models. The Ozawa model fits in the PP/SEBS-g-MA blends and indicates the effect of SEBS-g-MA copolymer on the crystallization process of polypropylene. Augis–Bennet model has been used to calculate activation energy, ∆E, during non-isothermal crystallization process. The value of ∆E decreased with SEBS-g-MA due to flexibility of SEBS-g-MA by which movements of chains of PP become easier.

Dynamic Power Management and Control of a PV PEM Fuel-Cell-Based Standalone ac/dc Microgrid Using Hybrid Energy Storage

In this paper, a dynamic power management scheme (PMS) is proposed for a standalone hybrid ac/dc microgrid, which constitutes a photovoltaic (PV)-based renewable energy source, a proton exchange membrane fuel cell (FC) as a secondary power source, and a battery and a supercapacitor as hybrid energy storage. The power management algorithm accounts for seamless operation of the microgrid under various modes and state-of-charge limit conditions of hybrid energy storage when all the sources, storages, and loads are connected directly at the dc link. The PMS generates current references for dc converter current controllers of the FC, the battery, and the supercapacitor. The average and fluctuating power components are separated using a moving average filter. The dc-link voltage regulation under dynamic changes in load and source power variation is proposed. Also, PV power curtailment through control is formulated. The proposed power management is modified and extended to multiple PV generation systems and batteries, with all the sources and storages geographically distributed and operating under multitime-scale adaptive-droop-based control with supervisory control for mode transition. The proposed PMS is validated using simulation results. Also, field programmable gate array/Labview-based laboratory-scale experimental results are presented to validate the PMS under various critical conditions.

Dynamic power management of PV based islanded microgrid using hybrid energy storage

This paper presents the power management scheme of PV based islanded microgrid using battery and supercapacitor hybrid energy storage under dynamic load conditions. The energy management scheme employs hysteresis controlled bidirectional dc-dc converter for battery and supercapacitor. The constant power fluctuations are compensated using battery as energy buffer while transient power fluctuations are compensated using supercapacitor as energy buffer. The three phase VSC supplying dynamic load power is decoupled controlled to regulate voltage and frequency of the ac bus. The proposed control scheme enhances the battery life and manages the power variations under varying irradiance conditions without losing MPPT of PV system.

Coordinated controller design and stability analysis of DC microgrid with constant power load

This paper presents a coordinated approach for the tuning of power electronic controllers and stability analysis considering constant power load in a DC microgird. The system consists of AC and DC loads, comprising of constant voltage and constant power characteristics. Constant power loads can be a potential source of instability for the system to which it is connected. Coordinated tuning of all the controllers is proposed to ensure enhanced dynamic stability of the system under the scenario considered. An eigenvalue based objective function is employed to find the optimal gains of all the controllers using swarm based intelligent optimization technique. Further, the stability of the system is verified using the impedance based stability criterion proposed by Middlebrook. The results are verified using time domain simulations under different system conditions. Time domain simulations are carried out in MATLAB/Simulink environment.

Dynamic response of nonlinear electrical analogue hydroelectric turbine model

Nonlinear model of hydroelectric turbine model with elastic water column in penstock consider the effects which cause travelling waves: pressure and flow due to elasticity of steel in penstock and compressibility of water. This paper proposes two nonlinear electrical analogue turbine models of hydroelectric plants, non-dissipative model and approximated model. Dynamic response of the proposed model is compared with the nonlinear travelling wave model. Frequency response analysis of approximated electrical analogue turbine model for different diameter to length ratio is studied.