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Abstract
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Minimization of Total Harmonic Distortion (MTHD) for the line-to-line output
voltage of multilevel inverters has been studied in this work. Harmony Search (HS) Algorithm
with artificial neural networks (ANN) has been employed to solve the aforementioned problem
with considering constant and alterable DC sources in order to minimize Total Harmonic
Distortion more efficiently. The nearest solutions provided by HSA obtain a smooth data set
that is desired for the neural network training. MTHD is suitable for some cases, e.g. multilevel
electrical drives and flexible AC transmission system devices such as multilevel static VAR
compensator, multilevel unified power quality conditioner and multilevel unified power flow
controller, where DC link voltages are altering. MTHD not only optimizes the switching
angles, also finds the optimum values for DC links. In this work THD minimization with
employing both constant and alterable DC sources has been researched and compared with
each other. Also a comparison is made with a recently published paper using GA, which
validates that the proposed scheme is more efficient in this regard. Numerical results for a test
case, seven-level inverter, reveal that the presented method is feasible.
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