Current Issue : January - March Volume : 2018 Issue Number : 1 Articles : 5 Articles
A new analog technique is proposed in order to track the maximum power point (MPP) of PV panels. The proposed technique\nuses the well-known simple functions of electronic circuits. The proposed technique is validated by applying it to boost based off\ngrid PV system. The simulation of the PV system was done on the circuit oriented simulator Proteus-ISIS. A good efficiency of the\nanalog technique (more than 98%) was registered.The variation of irradiation was introduced in order to study the robustness of\nthe proposed analog MPPT technique....
To eliminate the influence of the inconsistency on the cycle life and the available capacity\nof battery packs, and improve the balancing speed, a novel inductor-based layered bidirectional\nequalizer (IBLBE) is proposed. The equalizer is composed of two layers of balancing circuits connected\nin parallel. Each layer contains multiple balancing sub-circuits based on buck-boost converters.\nThese balancing sub-circuits can equalize the corresponding cells simultaneously, and allow the\ndynamic adjustment of equalization path and equalization threshold. Analysis and simulation\nresults demonstrate the IBLBE has a higher level balancing speed than other equalizers based on\nswitched-capacitor or switched-inductor converters, and reduces the balancing time by 30% compared\nto existing inductor-based parallel architecture equalizers (PAEs). Experimental results are presented\nto validate the analysis and effectiveness of the proposed equalizer....
This paper presents a grid connected photovoltaic system (PV) with a proposed\nhigh voltage conversion ratio DC-DC converter which steps up the variable\nlow input voltages of photovoltaic module to the required DC link voltage.\nThis voltage is applied to an H-bridge inverter which converts DC voltage\ninto AC voltage and a low pass filter is used to filter the output. By adjusting\nthe duty ratio of switches in DC-DC converter, the magnitude of inverter�s\noutput voltage is controlled. The frequency and phase synchronization\nare ensured by a feedback signal taken from the grid. In this way, inverter\nis synchronized and connected with the grid to meet the energy demand. The\nPV system has been designed and simulated....
Aiming to integrate the respective merits of the\nswitched-capacitor converter and the quasi-Z-source converter.\nAn novel high step-up quasi-Z-source DCââ?¬â??DC\nconverter with a single switched-capacitor branch is proposed.\nCompared to other high boost DCââ?¬â??DC converters,\nthe proposed converter can provide higher output voltage\ngain, lower current stress across the switches, and lower\nvoltage stress across the output diodes by using the same or\nsimilar passive and active components. Therefore, the\nefficiency and reliability of the converter can be improved.\nThe topological derivation, operating principle, parameter\nselection, and comparison with other DCââ?¬â??DC converters\nare presented. Finally, both simulations and experimental\nresults are given to verify the characteristics of the proposed\nconverter....
A conventional steady-state power flow security check only implements point-by-point\nassessment, which cannot provide a security margin for system operation. The concept of a\nsteady-state security region is proposed to effectively tackle this problem. Considering that the\ncommissioning of the increasing number of HVDC (High Voltage Direct Current) and the fluctuation\nof renewable energy have significantly affected the operation and control of a conventional AC\nsystem, the definition of the steady-state security region of the AC/DC power system is proposed\nin this paper based on the AC/DC power flow calculation model including LCC/VSC (Line\nCommutated Converter/Voltage Sourced Converter)-HVDC transmission and various AC/DC\nconstraints, and hence the application of the security region is extended. In order to ensure that the\nproposed security region can accurately provide global security information of the power system\nunder the fluctuations of renewable energy, this paper presents four methods (i.e., a screening method\nof effective boundary surfaces, a fitting method of boundary surfaces, a safety judging method,\nand a calculation method of distances and corrected distance between the steady-state operating\npoint and the effective boundary surfaces) based on the relation analysis between the steady-state\nsecurity region geometry and constraints. Also, the physical meaning and probability analysis of the\ncorrected distance are presented. Finally, a case study is demonstrated to test the feasibility of the\nproposed methods....
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