Abstract
The use of photovoltaic (PV) systems as the energy source of electrical distributed generators (DG) is gaining popularity, due to the progress of power electronics devices and technologies. Large-scale solar PV power plants are becoming the preferable solution to meet the fast growth of electrical energy demand, as they can be installed in less than one year, as compared to around four years in the case of conventional power plants. Modular multilevel inverters (MMIs) are the best solution to connect these large-scale PV plants to the medium-voltage (MV) grid, due to their numerous merits, such as providing better power quality, having higher efficiency, providing better reliability, and their scalability. However, MMIs are still progressing and need some improvement before they can be implemented safely in the industrial, medium, and high voltage networks. The main purpose of this paper is to review the present MMIs topologies when used in PV applications. The review aims to present a comprehensive study of the various recent submodule circuits associated with MMI topologies. Maximum power point tracking (MPPT) control schemes for PV inverters will be explored extensively. Then, the different control strategies of PV MMIs will be presented and compared to give a holistic overview of the submodules balancing techniques, ranges, and capabilities under balanced and unbalanced grid conditions. In addition, the paper will discuss the future of PV MMIs systems in electricity networks.
Highlights
The European Union (EU) countries are committed to reducing their dependency on fossil fuels and increasing the use of renewable energy sources, such that greenhouse gas emissions should be reduced by 80–95% in their 30-year plan, as compared with the year 1990
MPPTcontroller design is a crucial challenge for the penetration of large-scale PV systems in MV networks and requires further consideration regarding the maintenance of stability, especially with increasing output power and the necessity of multi-layer hierarchal Maximum power point tracking (MPPT)
This paper presented a comprehensive review of multilevel inverters that can be employed in high-power PV applications
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. The following points should be considered in the designing of a futuristic large-scale PV plant: (1) galvanic isolation is necessary between the input PV arrays and the MV grid for safety reasons and to eliminate the common-mode voltages and currents; (2) the power-semiconductor devices’ ratings and losses; (3) maximum power extraction during shading; and (4) the sizes and weights of the step-up transformer and passive filters [22,23] In this context, modular multilevel inverters (MMIs) emerge as a potential solution to solve the problems and improve the performance of large-scale PV systems. Using the same idea of employing a DC–DC converter within an MMC topology, as shown, a dual active-bridge (DAB) isolated converter was utilized to connect PV modules to a half-bridge SMs [84] This circuit has several advantages, such as an independent MPPT, improved safety because of galvanic isolation, and PV modules’. This has a negative impact on the topology’s performance, especially when used in large-scale PV power systems
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
