Techno-Economic Comparison of Multilevel Inverters and Determining the Optimal Structure for using in Solar Plants

Abstract

Among the various structures presented for inverters in photovoltaic systems, multilevel inverters are the key structure due to their numerous advantages over other inverters, are now widely used in photovoltaic systems. However, a variety of inverters makes different choices for users of photovoltaic systems, that each has its own advantages and disadvantages. Therefore, it seems necessary to study multilevel inverters and their performance. In this paper, by studying different structures of multilevel inverters, the optimal structure in terms of structural complexity, electrical stresses on various components, cost, weight, losses and THD harmonic index for photovoltaic systems is presented. In order to identify the optimal structure, the most common multilevel inverters are compared and two main categories of inverter related indices and indices related to their performance have been studied. Matlab software is used to perform the simulations. The structures investigated are neutral-point-clamped multilevel inverters (NPC-MLI), flying capacitor multilevel inverter (FC-MLI) and cascade H bridge multilevel inverter (CHB-MLI).