Modular Multilevel Photovoltaic Interfaced Converter with Low Voltage Energy Integration for DC Systems

Conference paper (2019)

Authors

Mladen Gagic DC systems, Energy conversion & Storage - EEMCS
K. Huang DC systems, Energy conversion & Storage - EEMCS
Z. Qin DC systems, Energy conversion & Storage - EEMCS
Jan Abraham Ferreira ESE Programmes - EEMCS
Research Group
DC systems, Energy conversion & Storage (EEMCS) (TU Delft)
Power flow control Modularity Cascade Multifrequency Energy-storage LV dc Photo-voltaic
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Published Date

2019

Language

English

Reuse Rights

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Faculty

Electrical Engineering, Mathematics and Computer Science

Department

Electrical Sustainable Energy

Research Group

DC systems, Energy conversion & Storage

Abstract

This paper presents a multilevel, cascaded converter topology that allows for integrations of combined photovoltaic and battery storage units. The modular features of the system enable the series connection of PV panels that, in turn, have a parallel connection to a specified voltage level. These voltage levels stem from a series string of power electronic submodules. Likewise, low voltage energy storage units are interfaced to the upper arm of the system via identical converter modules and provide various directions of dc and ac active power flow, depending on the mode of operation. By implementing additional, nestled current loops, guided by passive filters, the system controls the power flow between the photo-voltaic string, batteries and the low voltage dc terminal. The enhanced level of power flow allows the converter to achieve both a controlled energy exchange as well as various auxiliary services in the DC system. This paper demonstrates three distinct types of power flow that are achievable with by combining the multilevel topology along with multifrequency operations. Simulation results from a representative system model are utilised to demonstrate the three possible modes of operation.