Performance Analysis of Medium-Voltage Grid Integration of PV Plant Using Modular Multilevel Converter

Abstract

Modular multilevel converter (MMC) topology has emerged as an attractive solution for Photovoltaic (PV) applications. Such a structure due to its inherent modularity allows distributed architecture of utility scale PV plant. Moreover, converters scalability allows for direct connection to the medium voltage grid by avoiding the need for the step-up transformer. The isolation is provided at the interface between the PV array and the MMC by using an isolated DC-DC converter. In this work the MMC performance is evaluated and compared with the main central inverter configurations in terms of annual energy yield, efficiency and levelized cost of energy. Efficiency curve from no load to full load is obtained for the MMC through simulations using standard IGBT half-bridge modules. It is seen that the efficiency curve is flat for a wide range of loads resulting in a higher annual energy yield and lower Levelized Cost of Energy (LCOE).