Abstract: These days, the industrial trend is moving away from heavy and bulky passive components to power converter systems that use more and more semiconductor elements. Also, it is difficult to connect the traditional converters to the high and medium voltage. For these reasons, a new family of multilevel inverters has appeared as a solution for working with higher voltage levels. Different modulation topologies like Sinusoidal Pulse Width Modulation (SPWM), Selective Harmonic Elimination Pulse Width Modulation (SHE-PWM) are available for multilevel inverters. In this work, different hybrid modulation techniques which are combination of fundamental frequency modulation and multilevel sinusoidal-modulation are compared. The main characteristic of these modulations are reduction of switching losses with good harmonic performance and balanced power loss dissipation among the device. The proposed hybrid modulation schemes are developed and simulated in Matlab/Simulink for cascaded H-bridge inverter. The results validate the applicability of the proposed schemes for cascaded multilevel inverter.
Abstract: In this paper, influence of harmonics on medium
voltage distribution system of Bogazici Electricity Distribution Inc.
(BEDAS) which takes place at Istanbul/Turkey is investigated. A ring
network consisting of residential loads is taken into account for this
study. Real system parameters and measurement results are used for
simulations. Also, probable working conditions of the system are
analyzed for 50%, 75%, and 100% loading of transformers with
similar harmonic contents. Results of the study are exhibited the
influence of nonlinear loads on %THDV, P.F. and technical losses of
the medium voltage distribution system.