An energy balancing strategy for modular multilevel converter based grid-connected photovoltaic systems
Document Type
Article
Publication Date
9-1-2021
Abstract
Modular multilevel converters (MMC)s are promising candidates for large-scale grid-connected photovoltaic (PV) systems. Due to their modular structure, MMCs provide a direct connection of the PV arrays to the converter submodules. They also offer scalability, independent maximum power point tracking, and enhanced power quality with internal power flow capabilities. However, the intermittent nature of PV arrays introduces a power unbalance inside the converter, which affects its operation. This paper addresses the issue and proposes an energy balancing strategy for the grid-connected MMC-based PV system. It uses the internally generated leg currents to control the power flow inside the converter and inject a three-phase balanced current to the grid with low total harmonic distortion. Compared to the existing strategies, the proposed strategy can overcome any condition of the power unbalance with minimal submodule voltage fluctuations. A 162-kW, 9-kV PV grid-connected system is modelled and simulated in MATLAB Simulink environment. The corresponding results are presented to demonstrate the effectiveness of the proposed control strategy for grid-connected PV systems.
Keywords
Engineering, Electrical, Electronic, Photovoltaic systems
Divisions
fac_eng
Funders
Ministry of Education, Malaysia[LRGS/1/2019/UKM/01/6/3],Universiti Malaya[ST009-2020]
Publication Title
IET Power Electronics
Volume
14
Issue
12, SI
Publisher
Institution of Engineering and Technology (IET)
Publisher Location
111 RIVER ST, HOBOKEN 07030-5774, NJ USA