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If sensitive loads are connected to the point of common coupling (PCC), compensation should be carried out in order to reduce PCC voltage harmonics. In this case, compensation is performed by the interface converters of distributed generation (DG) units. In this paper, a novel method is proposed for voltage harmonics compensation in islanded microgrids. The proposed method is capable of adjusting compensation percentage in proportion to the existing level of distortion at PCC. Also, this controller provides a proper sharing of compensation workload, considering the nominal capacity of DGs, which will improve the sharing of nonlinear load. Also, to decrease the asymmetry among phase impedances of microgrid, a novel structure is proposed to generate virtual impedance. At fundamental frequency, the proposed structure for the virtual impedance improves the control of the fundamental component of the power, and at harmonic frequencies, it acts to adaptively improve nonlinear load sharing among DG units. In the structures of the proposed harmonics compensator and the proposed virtual impedance, a self-tuning filter is used for separating the fundamental component from the harmonic components. This self-tuning filter decreases the number of the phase-locked loops. The simulation results in MATLAB/SIMULINK environment show the efficiency of the proposed approach in improving load sharing and decreasing voltage harmonics. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

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Proposed a new structure based on the multi-level saturation controllable reactor (MLMCR), can effectively reduce the MLMCR output harmonic contained in the current. Having a different length and area of the core portion of the apparatus by a plurality of MLMCR, Levels magnetic is generated due to the magnetic saturation in the work process the harmonic current of the different phases, to generate harmonic currents through the magnetic valve can achieve the purpose of reducing the output current contained in the harmonic. In this paper, based on the characteristics of the device on the core structure, the establishment of Mathematical model MLMCR harmonic characteristics, and the following conclusions: There are three main factors to affect the size of the MLMCR output harmonic, Respectively, for the the core classification number and the length of the cross-section and area, of which the latter two of MLMCR output harmonic greatest impact. By The HS parameters to optimize the design can makes MLMCR output total harmonic current maximum does not exceed the amount 1.8% of the rated output current. [ABSTRACT FROM AUTHOR]

Intrinsic line capacitance in long AC grids of high voltage level must be compensated. Usually this is accomplished by shunt reactors, which are used to compensate the effects of line capacitance, particularly to limit voltage rise on open circuits or small loads. Magnetically controlled reactor (MCR) is a new device that its inductance can be adjusted continuously by DC pulsing through a special winding. MCR can improve the voltage profile and decrease power losses, but if its parameters are not assigned properly, it cannot be exploited correctly. In this paper, assigning MCR parameters in order to minimize power losses is studied. Two examples of power systems are used to illustrate the ideas presented throughout the paper. [ABSTRACT FROM AUTHOR]

Shunt reactors are used to compensate the effects of line capacitance, particularly to limit voltage rise on open circuits or small loads. A magnetically controlled reactor is a device in which a DC pulsating through a special winding controls the inductive susceptance. Magnetically controlled reactors enhance transmission capability and save energy, especially in compact increased surge-impedance-loading power lines. The response of a thyristor-controlled reactor in voltage regulation to the voltage variations in a transmission line is faster than that of a magnetically controlled reactor. Although a magnetically controlled reactor can be designed to respond like a thyristor-controlled reactor in as little as 0.02 sec, the price of magnetically controlled reactor depends on its response time. In high voltage transmission lines, voltage variations are not sudden, so the slow response of the magnetically controlled reactor with respect to the thyristor-controlled reactor is not important. The main objective of this article is to compare magnetically controlled reactors and thyristor controlled reactors from a transient behavior point of view, and a detailed model of a magnetically controlled reactor reactor is used to illustrate the ideas presented throughout the article. [ABSTRACT FROM AUTHOR]