Powerline Communications Through Series Connected Switched Mode Power Converters to Be Used in Solar Microinverters
1 online resource (151 pages) : PDF
University of North Carolina at Charlotte
Modern photovoltaic converters and energy storage modules are shifting to a cascaded or distributed module-level inverters to reduce the required voltage output of each module and thereby optimizing production costs. The switch to an AC-stacked architecture, where all modules are in series, requires a method of synchronization of the voltage and current output of each module to the grid since each module has no direct connection to the grid as to acquire such synchronization. Many different methods for communicating the zero crossing to each photovoltaic converter module are currently available but either increases plant level costs from running additional wiring for wired mediums or are susceptible to remote interference in wireless communication mediums potentially disrupting operation by either loss of synchronization or inaccurate timing of synchronization to the zero crossing of the grid.This research develops a current-mode based methodology for powerline communication and synchronization by which the photovoltaic converter and energy storage modules may detect the zero crossing and synchronize the converter operation to the grid. Included in the methodology is the use of series connected power electronics as a communications medium for the current-mode based means of power line communications. The developed communications model, generalized for all series connected power electronics, establishes a foundation for part the physical layer in the OSI model. This model is implemented and performance analyzed in synchronization of a physical system consisting of series connected inverters used in solar power conversion. The approach has been used to allow an 8-module, 120 V_RMS string to operate in the field for over six months without any synchronization or controls-related failures.
Weldon, ThomasParkhideh, BabakBrowne, Aidan
Thesis (Ph.D.)--University of North Carolina at Charlotte, 2018.
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