transformer coupled topology. All of these proposed solutions
adopt a control method commonly known as voltage equalization or “virtual parallel” operation, in which all distributed
converters strive to equalize the voltages of all PV submodules in a string. The distributed converters in the system run in
open loop, simplifying the control requirements while obviating the need for communication among converters. However,
the voltage equalization approach can only achieve nearmaximum power point (MPP) operation without truly seeking the
MPP of each individual submodule. The effectiveness of this
approach relies on the fact that the MPP voltages of submodules in a string are very close even if their MPP currents differ
significantly. This does require all the submodules to have very