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This paper presents control and configuration of photovoltaic fed unified power quality conditioner for the purpose of power quality enhancement. Literature studies convey that fixed PI gains used in the control schemes of Unified Power Quality Conditioners (UPQC) and PV-UPQC cannot easily adapt to various dynamic conditions. In this paper a novel online tunings method for PI control gains is adopted in the controllers of series and shunt converters of PV-UPQC. Unlike the previously implemented JAYA algorithm which has a single objective function utilized in the controller of DSTATCOM for improvement of only current quality, the new adaptive JAYA algorithm has two separate objective function, employed in shunt and series inverter control of PV-UPQC system for improvement of both current and voltage quality under various operational scenarios for power quality issues. The experimental results verify that implementation of JAYA based auto tuning PI controller increases the adaptivity of PV-UP-QC system towards various dynamic conditions. Results obtained are compared with conventional optimization algorithms with fixed PI gains pertaining to a distribution system for validating its efficacy.

Sub-zero weathered GFRP (glass fiber reinforced plastics) composites were aged in water at 60 C for different conditioning times to study fluid sorption kinetics under the influence of a thermal gradient. The effect of subsequent freezing of the conditioned samples on the retention of prior thermal history has been investigated. The variation in mechanical properties during the aging process was studied. One batch of the hydrothermally conditioned specimens was further subjected to sub-zero treatment at 20 C temperature. The samples which were subsequently frozen showed higher interlaminar shear strength (ILSS) initially, although this trend was reversed after a certain conditioning period. Thus, the present study aims to evaluate the mechanical behavior of polymer composites under the influence of extreme and complex conditions.

A new Lyapunov-based adaptive controller (LBAC) for a single stage three-phase gridconnected PV system (GCPVS) is proposed here. The uncertainties in solar irradiation affects the performance of the GCPVS. Further, ageing in the DC-link capacitor affects the PV voltage tracking. To achieve an improved performance of the GCPVS under both high and low irradiation, and under an aged DC-link capacitor, a new LBAC scheme has been proposed to control the PV voltage. In this LBAC, the gains of the controller are adapted online by a Lyapunov-based adaptation mechanism to provide the nominal tracking response of PV voltage. Further, a maximum power point tracking algorithm and grid current controllers are designed to transfer the maximum PV power to the grid, ensuring good power quality. As a result, improved performances of the GCPVS are achieved in terms of low PV voltage ripple, enhancement of delivered grid energy, and low grid current total harmonics distortion (THDs). Computer simulation studies are carried out in MATLAB/Simulink environment to verify the effectiveness of the proposed LBAC. Further, experiments are performed in a 2.5 kW GCPVS prototype for real time implementation of the proposed controller. The total harmonics distortion (THD) of grid currents is found to be within IEEE-1547 standards.This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

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The penetration of renewable energy sources (RESs) in the distribution system becomes a challenge for the reliable and safe operation of the existing power system. The sporadic characteristics of sustainable energy sources along with the random load variations greatly affect the power quality and stability of the system. Hence, it requires storage systems with both high energy and high power handling capacity to coexist in microgrids. An efficient energy management structure is designed in this paper for a grid-connected PV system combined with hybrid storage of supercapacitor and battery. The combined supercapacitor and battery storage system grips the average and transient power changes, which provides a quick control for the DC-link voltage, i. e., it stabilizes the system and helps achieve the PV power smoothing. The average power distribution between the power grid and battery is done by checking the state of charge (SOC) of a battery, and an effective and efficient energy management scheme is proposed. Additionally, the use of a supercapacitor lessens the current stress on the battery system during unexpected disparity in the generated power and load requirement. The performance and efficacy of the proposed energy management scheme are justified by simulation studies.