Photovoltaic central inverters: Performance evaluation and comparative assessment

Reliability, efficiency and cost are the deciding factors for the selection of photovoltaic central inverters those are used to evacuate power in large solar parks. Inverters used can be 2-level, 3-level (such as NPC and its variation) and cascaded bridge (symmetrical and asymmetrical) etc. Elimination of leakage current has a role on the modification of topology. In most of the cases a transformer is used to step up the voltage. Recently level doubling network (LDN) based asymmetric multilevel inverter topology (as central inverter for photovoltaic application) is reported in literature. This paper evaluates the performance of such topology in terms of efficiency, reliability and passive component requirement. Performance of the topology is then compared with the well-known topologies for photovoltaic central-inverter in industry. A 100kVA central photovoltaic inverter is considered for the study. Efficiency is estimated by using Semisel software available online by selecting appropriate devices for each cell. Better performance is expected for higher rating of central converter.